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The loss of probiotics viability in yogurts and fermented milk is a significant challenge in producing yogurt and fermented milk. Thus, pre-exposure of probiotics to stress conditions can be a viable alternative to increase the probiotic viability. Moreover, the use of fruit pulp and agro-industrial residues in these products has demonstrated promising results in promoting growth and improving the viability of probiotics. Thus, this study aimed to evaluate the effects of pre-exposure to acid, oxidative and osmotic stress on the growth and viability of Lactobacillus acidophilus in yogurts and naturally fermented milk containing buriti (Mauritia flexuosa Mart.) pulp or orange byproduct. L. acidophilus was individually pre-exposed to acid, oxidative, and osmotic stress and used in the production of yogurts and fermented milk to determine both the acidification profile and growth of the cultures. Furthermore, during cold storage, the post-acidification profiles and viability of microbial cultures added to the yogurts and fermented milk were monitored. Results showed that pre-exposure to stress conditions influenced the growth parameters as the growth rate (μ) and lag phase (λ) of L. acidophilus and the starter cultures of S. thermophilus and L. delbrueckii subsp. bulgaricus. Moreover, an increase in the viability of L. acidophilus - pre-exposed to acid stress - was observed on the 21st day of storage of natural yogurts containing orange byproduct compared with non-stressful conditions. This study reports new data on the growth of probiotic cultures pre-exposed to stress conditions in products added of pulps and agro-industrial residues, which have not yet been shown in the literature., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

High-methoxyl pectin (HMP, 72.5 % esterification degree and galacturonic acid content of 67.9 %) was extracted from grape pomace using a sequential ultrasound-microwave extraction. The extracted HMP was used to develop low-fat synbiotic set yogurts containing probiotic cells. Higher grape pomace pectin (GPP) concentrations (0.5-2 %) increased the probiotic bacterial population of Lactobacillus acidophilus LA-5 and Bifidobacterium bifidum BB-12. Higher cell viability was observed for L. acidophilus LA-5 compared to B. bifidum BB-12. A response surface optimization showed that the presence of 8.08 Log CFU mL -1 L. acidophilus LA-5 and 1.88 % HMP experimentally resulted in the best probiotic viability (10.83 ± 0.11 Log CFU mL -1 ), overall acceptability (8.03 ± 0.06), and pH (4.25 ± 0.05) values. Compared to pectin-free probiotic yogurts, the optimal yogurt gels presented higher probiotic survivability, lower syneresis, and superior storage-dependent sensory attributes during 21 days of storage. However, a 14-day storage period was generally deemed suitable. The GPP-containing yogurt compared to the pectin-free sample exhibited higher colloidal stability with a larger particle size (433.8 nm vs. 272.5 nm) and lower zeta potential (-20.4 mV vs. -10.6 mV). Field emission-scanning electron (FE-SEM) and fluorescent (FLM) microscopy images confirmed a denser microstructure for GPP-enriched yogurts. The chemical interactions in the yogurt were not affected by enriching with GPP as investigated by FTIR, whereas the steady and dynamic rheological properties were significantly improved. GPP-enriched yogurt had a firmer gel structure with a larger linear region and lower G' compared to the control, indicating a semi-solid state. The GPP as a multi-functional prebiotic ingredient would be promising in designing healthier food products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Soybean hull polysaccharides (SHPS) enhance the physicochemical properties of plant-based yogurt. However, their effects on the nutritional profile and biochemical mechanisms remain unclear. This study aimed to assess the impact of SHPS addition on the nonvolatile components of plant-based yogurt and its underlying mechanisms through widely targeted metabolomics analysis. The results demonstrated that the addition of SHPS (0.2 %-1.0 % w/v) enhanced the levels of free amino acids, sugars, and organic acids, with the addition of 0.6 % w/v being particularly effective in improving yogurt quality. Widely targeted metabolomics analysis revealed 278 differential metabolites between yogurt supplemented with 0.6 % SHPS (SPY) and the control sample. SHPS increased the content of various metabolites, including amino acids and derivatives, saccharides, organic acids, and flavonoids, among others. Key metabolic pathways affected by SHPS included pantothenate and CoA biosynthesis; valine, leucine, and isoleucine biosynthesis; and benzoate degradation. As the primary component of SHPS, galacturonic acid affected the metabolic products in yogurt by participating in the pentose and glucuronate interconversions and ascorbate and aldarate metabolism pathways. These findings elucidate the role of SHPS in modulating the nutritional composition of plant-based yogurt, offering valuable insights into its functional mechanisms in food processing., Competing Interests: Declaration of competing interest None., (Copyright © 2024. Published by Elsevier B.V.)

A fluorescent sensor based on nitrogen-doped graphene quantum dots (N-GQDs) was developed for the smartphone-assisted colorimetric determination of diflunisal. The fluorescence source was embedded with zinc oxide (ZnO) in a molecularly imprinted polymer (ZnO@N-GQDs@MIP). The quantitative analysis was based on the fluorescence quenching caused by electron transfer from the nanoprobe to diflunisal. The sensor demonstrated linearity in the range of 0.10-50.0 μg L -1 with a limit of detection of 0.03 μg L -1 . Smartphone-assisted on-site determination produced linearity in the range of 1.0-50.0 µg/L with a limit of detection of 0.30 μg L -1 . The developed sensor was applied to determine diflunisal in milk, egg and yogurt samples. Recoveries ranging from 94.8 to 103.7 % were achieved with a RSD below 2.0 % measured by fluorescence spectroscopy, and from 94.9 to 106.9 % with a RSD of <6 % smatphone-assisted measurement. Comparison of the detection outcomes of both methods with those of high-performance liquid chromatography revealed consistent results, demonstrating the accuracy of the developed method, which was also sensitive, selective, and fast. Notably, the portable and easy-to-read smartphone-assisted method is suitable for on-site application., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A novel approach was developed to simultaneously determine the contents of vitamins D 2 , D 3 , K 1 , and K 2 in yogurt fortified with nanoencapsulated vitamins D and K. This method combines QuEChERS extraction with UPLC-APCI-MS/MS analysis. Optimization of the QuEChERS process included fine-tuning the addition of salts using response surface methodology based on the Box-Behnken design. Under the optimized conditions, the developed method exhibited an excellent linearity (R 2 > 0.999) across concentrations ranging from 0.5 to 500 µg/L. The limits of detection and quantification (LOD and LOQ) were found to be 0.01-0.04 µg/L and 0.04-0.11 µg/L, respectively, with precision, accuracy, and recovery rates exceeding 94.88 %, and accompanied by acceptable relative standard deviations. Comparative analysis with traditional methodologies revealed the significant advantages of the proposed approach. Previous techniques such as liquid-liquid extraction combined with saponification are time-consuming and require high sample quantities. In addition, dispersive liquid-liquid microextraction requires a long analysis time and exhibits a poor sensitivity, particularly in terms of its LOD and LOQ values. In contrast, our method offers a straightforward, efficient, and reliable sample preparation technique suitable for detecting vitamins D 2 , D 3 , K 1 , and K 2 in a yogurt matrix. This study not only demonstrates the feasibility of applying the QuEChERS method for stable vitamin quantification in yogurt, but it also represents an innovative contribution to enhancing the detection sensitivity and efficiency in food analysis. By emphasizing these methodological advancements and comparative benefits, this research underscores the significance of adopting advanced analytical approaches in food science., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

This study aims to develop a novel and selective method for the detection of natamycin (E235) in yoghurt. The suggested method adopts an application of Hantzsch reaction to turn on the fluorescence behavior of natamycin (blue fluorescence), allowing its sensitive and selective determination in yoghurt samples without any overlapping at 485 nm. The originality of the research lies in the fact that this application takes place for the first time, also the detection (LOD) and quantification (LOQ) limits were very low (0.02 and 0.06μg mL -1 , respectively) with a linear concentration range of 0.1-1.0 μgmL -1 . Moreover, the developed method was employed for the detection of E235 in yoghurt sample with a good recoveries (98.80 ± 1.20-99.20 ± 1.15 (%), over a concentration range of 0.5-1.0 μgmL -1 , (LOD = 0.04 and LOQ = 0.12 μgmL -1 ). Furthermore, the specificity and convenient application of our intended method is an attempt to determine E235 in milk anddairy products with easily followable steps., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Because of the poor stability and rheological properties of fat-free stirred yogurt fortified with fruit pulp, new functional polysaccharides as a natural emulsifier, which can increase viscosity in the aqueous phase, may be needed. This study aimed to evaluate the effects of Exidia yadongensis polysaccharide (EYP) as emulsifier on the stability, aroma, and antioxidant activities of mango buffalo yogurt at 4 °C for 25 days. The yogurt with 15 g/L EYP gave a higher content of 215 g/L total solids, 11.3 g/L exopolysaccharides, 0.10 g/L total polyphenols, 630.5 g/L water-holding capacity, and 11.43 g/kg total free amino acids, and maintained better texture, DPPH scavenging activity of 54.05 % and OH scavenging rates of 67.16 %. Moreover, the EYP exhibited the expected ability to weaken postacidification, syneresis, and growth of microorganism, and greatly promote the textural, rheological properties, suspension stability, microstructure, and aroma profiles of stirred mango-flavored buffalo yogurt (p < 0.05). In addition, the addition of 15 g/L EYP can inhibit protein degradation and improve the stability of secondary structure of the protein complex in mango yogurt during 25 days of storage. Therefore, EYP (15 g/L) could be used as natural positive functional factors and emulsifiers in such fat-free stirred yogurt industry., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Aqueous lupine seeds (Lupinus albus L.) extracts were evaluated as a natural fat substitute in low-fat yogurt production. Thus, the chemical composition, particle size, molecular weight, total phenolic (TPC), and total flavonoids (TFC) of the selected extract were estimated. Also, the antimicrobial activity and antioxidant capacity of selected extract were investigated. Yogurt with neutral lupine extract (NeLP) had the highest all sensorial attributes compared to other extracts. Also, the incorporation of NeLP during low-fat yogurt processing increased the solid content, and viscosity, as well as improved the textural profile and sensorial attributes without any negative effect on the yogurt's color. SEM micrographs of NeLP-yogurt microstructure showed a matrix characterized by large fused casein micelles clusters with comparatively lower porosity compared to control yogurt (without NeLP). The chemical composition of NeLP indicated that the major sugar constituents are glucose and galactose with different molar fractions. The molecular weight of NeLP is 460.5 kDa with a particle size of 1519.9 nm. Also, IC 50 of NeLP is 0.589 mg/ml, while TPC and TFC are 7.17, and 0.0137 g/100 g sample, respectively. Hence, lupine neutral extract (0.25%) could be used as a fat replacer or texture improver ingredient in such low-fat yogurt which led to improved its characteristics without any negative defect during 7 days at 5 °C., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Samia A. Ahmed reports was provided by National Research Centre., (Copyright © 2024. Published by Elsevier B.V.)

The effect of sodium alginate (SA) on the yogurt stability and the related mechanisms were investigated. It was found that low-concentration SA (≤0.2 %) increased the yogurt stability, while high-concentration SA (≥0.3 %) decreased the yogurt stability. Sodium alginate increased the viscosity and viscoelasticity of yogurt and this effect was positively correlated with its concentration, suggesting that SA worked as the thickening agent in yogurt. However, addition of ≥0.3 % SA damaged the yogurt gel. These results suggested that interaction between milk protein and SA might play an important role in the yogurt stability besides the thickening effect. Addition of ≤0.2 % SA did not change the particle size of casein micelles. However, addition of ≥0.3 % SA induced aggregation of casein micelles and increased the size. And the aggregated casein micelles precipitated after 3 h storage. Isothermal titration calorimetry analysis showed that casein micelles and SA were thermodynamically incompatible. These results suggested that the interaction between casein micelles and SA induced aggregation and precipitation of casein micelles, which was critical in the destabilization of yogurt. In conclusion, the effect of SA on the yogurt stability was dependent on the thickening effect and the interaction between casein micelles and SA., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest to this work., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Yak yogurt, one of the naturally fermented dairy products prepared by local herdsmen in the Qinghai-Tibet Plateau, contains a diverse array of microorganisms. We isolated and identified a novel Streptococcus thermophilus strain, ZJUIDS-2-01, from the traditional yak yogurt. We further purified and carried out detailed structural, physiochemical, and bioactivity studies of an exopolysaccharide (EPS-3A) produced by S. thermophilus ZJUIDS-2-01. The weight-average molecular weight (Mw) of EPS-3A was estimated to be 1.38 × 10 6  Da by High-Performance Gel Permeation Chromatography (HPGPC). The monosaccharide analysis established its composition to be glucose, galactose, N-acetyl-D-galactosamine, and rhamnose in a ratio of 5.2:2.5:6.4:1.0. The molecular structure of EPS-3A was determined by the combination of permethylation analysis, FT-IR, and NMR spectroscopic techniques. The ζ-potential measurements indicated that EPS-3A had a pKa value of ~4.40. The DSC yielded a melting point (T m ) of 80.4 °C and enthalpy change (ΔH) of 578 J/g for EPS-3A, comparable to those of the xanthan gum (XG), a commercial EPS. EPS-3A exhibited better O/W emulsion stability and flocculating capacity than XG. Furthermore, it also demonstrated similar antioxidant activity to XG and promising in vitro antibacterial properties. This work evidenced that EPS-3A derived from S. thermophilus ZJUIDS-2-01 holds the potential for food and industrial applications., (Published by Elsevier B.V.)

Background: Although a link between regular yogurt consumption and mortality appears plausible, data are sparse and have yielded inconsistent results., Objectives: We examined the association between regular yogurt consumption and risk of all-cause and cause-specific mortality among US women and men., Methods: A total of 82,348 women in the Nurses' Health Study and 40,278 men in the Health Professionals Follow-Up Study without a history of cardiovascular disease (CVD) and cancer in 1980 (women) or 1986 (men) were followed up until 2012. Yogurt consumption was assessed by updated validated FFQs., Results: During 3,354,957 person-years of follow-up, 20,831 women and 12,397 men died. Compared with no yogurt consumption, the multivariable-adjusted HRs (95% CIs) of mortality were 0.89 (0.86, 0.93), 0.85 (0.81, 0.89), 0.88 (0.84, 0.91), and 0.91 (0.85, 0.98) for ≤1-3 servings/mo, 1 serving/wk, 2-4 servings/wk, and >4 servings/wk in women (P-trend = 0.34), respectively. For men, the corresponding HRs (95% CIs) were 0.99 (0.94, 1.03), 0.98 (0.91, 1.05), 1.04 (0.98, 1.10), and 1.05 (0.95, 1.16), respectively. We further noted inverse associations for cancer mortality (multivariable-adjusted HR comparing extreme categories: 0.87; 95% CI: 0.78, 0.98; P-trend = 0.04) and CVD mortality (HR: 0.92; 95% CI: 0.79, 1.08; P-trend = 0.41) in women, although the latter was attenuated in the multivariable-adjusted model. Replacement of 1 serving/d of yogurt with 1 serving/d of nuts (women and men) or whole grains (women) was associated with a lower risk of all-cause mortality, whereas replacement of yogurt with red meat, processed meat (women and men), and milk or other dairy foods (women) was associated with a greater mortality., Conclusions: In our study, regular yogurt consumption was related to lower mortality risk among women. Given that no clear dose-response relation was apparent, this result must be interpreted with caution., (Copyright © The Author(s) 2020.)

Foods are not only a collection of individual components but are complex matrices. The food matrix is defined by the USDA as "the nutrient and nonnutrient components of foods and their molecular relations." The matrix of a food is an important factor in evaluating its nutritional and health contributions to the consumer. Dairy foods are a complex mix of various nutrients and other components, which together form the food matrix. There are three main types of dairy food matrices: liquid (milk, some fermented milks), semi-solid (yogurt, some fresh cheeses), and solid (most cheeses). The nutritional value of dairy foods is determined by their nutrient composition and matrix structure, which can affect digestibility and the bioavailability of nutrients. Additionally, a number of studies have shown that the health effects of dairy products, of similar nutrient content, vary by their matrix., (Copyright © American Society for Nutrition 2019.)

Background: Because consumption of conventional yogurt has beneficial effects in a healthy population, and insulin resistance (IR) is the mutual pathogenesis in nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome (MetS), we hypothesized that yogurt would ameliorate IR in patients with NAFLD and MetS., Objectives: The aim of this study was to investigate the effects of yogurt on IR and secondary endpoints including liver fat, gut microbiota, and serum biomarkers of inflammation and oxidative stress in obese women with NAFLD and MetS., Methods: One hundred obese women aged 36-66 y with both NAFLD and MetS were randomly assigned to consume 220 g/d of either conventional yogurt or milk for 24 wk. At baseline and week 24, we measured anthropometric indices, serum glucose, insulin, lipids, and cytokines in all participants, and liver fat and gut microbiota in 20 participants randomly selected from each group., Results: Forty-eight participants from the yogurt group and 44 from the milk group completed the intervention. Compared with milk, yogurt significantly decreased the homeostasis model assessment of insulin resistance (-0.53; 95% CI: -1.03, -0.02), fasting insulin (-2.77 mU/L; 95% CI: -4.91, -0.63 mU/L), 2-h insulin (-25.5 mU/L; 95% CI: -33.0, -17.9 mU/L), 2-h area under the curve for insulin (-29.4 mU/L · h; 95% CI: -44.0, -14.8 mU/L · h), alanine aminotransferase (-4.65 U/L; 95% CI: -8.67, -0.64 U/L), intrahepatic lipid (-3.44%; 95% CI: -6.19%, -0.68%), and hepatic fat fraction (-3.48%; 95% CI: -6.34%, -0.63%). Yogurt also decreased serum LPS (-0.31 EU/mL; 95% CI: -0.48, -0.14 EU/mL), fibroblast growth factor 21 (-57.76 pg/mL; 95% CI: -86.32, -29.19 pg/mL), lipids, and biomarkers of inflammation and oxidative stress, and altered gut microbiota composition. Mediation analysis showed that yogurt may improve IR by reducing serum lipids, inflammation, oxidative stress, and LPS., Conclusions: Yogurt was better than milk at ameliorating IR and liver fat in obese Chinese women with NAFLD and MetS, possibly by improving lipid metabolism, reducing inflammation, oxidative stress, and LPS, and changing the gut microbiota composition. This trial was registered at www.chictr.org.cn as ChiCTR-IPR-15006801., (Copyright © American Society for Nutrition 2019.)

In this work, fabrication of a novel and ultrasensitive electrochemical biosensor based on immobilization of tyrosine hydroxylase onto palladium-platinum bimetallic alloy nanoparticles/chitosan-1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide/graphene-multiwalled carbon nanotubes-IL/glassy carbon electrode for determination of L-tyrosine in some high tyrosine foods including cheese, egg and yogurt was reported. Immobilization of tyrosine hydroxylase onto the surface of the biosensor was performed by cross-linking tyrosine hydroxylase and chitosan through the addition of glutaraldehyde. Enzymatic biosensors employ the affinity and selectivity of catalytically active proteins towards their target molecules and here, the tyrosine hydroxylase selectively catalyzes the conversion of tyrosine to levodopa which can be oxidized at lower potentials than tyrosine. The modifications were characterized by electrochemical impedance spectroscopy, cyclic voltammetry, energy dispersive X-ray spectroscopic and scanning electron microscopy. Under optimal conditions, the biosensor detected tyrosine in concentration ranges of 0.01 × 10 -9 to 8.0 × 10 -9 mol L -1 and 8.0 × 10 -9 to 160.0 × 10 -9 mol L -1 with a limit of detection of 0.009 × 10 -9 mol L -1 . The biosensor was able to selective determination of tyrosine even in the presence of common interferents therefore, the biosensor was highly selective. The biosensor also showed good operational stability, antifouling properties, sensitivity, repeatability and reproducibility., (Copyright © 2018 Elsevier B.V. All rights reserved.)

FT-Raman quantitative analysis of nutritional parameters of yoghurts was performed with the help of partial least squares models. The relative standard errors of prediction for fat, lactose and protein determination in the quantified commercial samples equalled to 3.9, 3.2 and 3.6%, respectively. Models based on attenuated total reflectance spectra of the liquid yoghurt samples and of dried yoghurt films collected with the single reflection diamond accessory showed relative standard errors of prediction values of 1.6-5.0% and 2.7-5.2%, respectively, for the analysed components. Despite a relatively low signal-to-noise ratio in the obtained spectra, Raman spectroscopy, combined with chemometrics, constitutes a fast and powerful tool for macronutrients quantification in yoghurts. Errors received for attenuated total reflectance method were found to be relatively higher than those for Raman spectroscopy due to inhomogeneity of the analysed samples., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: The Australian Government has introduced a voluntary front-of-package labeling system that includes total sugar in the calculation., Objective: Our aim was to determine the effect of substituting added sugars for total sugars when calculating Health Star Ratings (HSR) and identify whether use of added sugars improves the capacity to distinguish between core and discretionary food products., Design: This study included packaged food and beverage products available in Australian supermarkets (n=3,610). The product categories included in the analyses were breakfast cereals (n=513), fruit (n=571), milk (n=309), non-alcoholic beverages (n=1,040), vegetables (n=787), and yogurt (n=390). Added sugar values were estimated for each product using a validated method. HSRs were then estimated for every product according to the established method using total sugar, and then by substituting added sugar for total sugar. The scoring system was not modified when added sugar was used in place of total sugar in the HSR calculation. Products were classified as core or discretionary based on the Australian Dietary Guidelines. To investigate whether use of added sugar in the HSR algorithm improved the distinction between core and discretionary products as defined by the Australian Dietary Guidelines, the proportion of core products that received an HSR of ≥3.5 stars and the proportion of discretionary products that received an HSR of <3.5 stars, for algorithms based upon total vs added sugars were determined., Results: There were 2,263 core and 1,347 discretionary foods; 1,684 of 3,610 (47%) products contained added sugar (median 8.4 g/100 g, interquartile range=5.0 to 12.2 g). When the HSR was calculated with added sugar instead of total sugar, an additional 166 (7.3%) core products received an HSR of ≥3.5 stars and 103 (7.6%) discretionary products received a rating of ≥3.5 stars. The odds of correctly identifying a product as core vs discretionary were increased by 61% (odds ratio 1.61, 95% CI 1.26 to 2.06; P<0.001) when the algorithm was based on added compared to total sugars., Conclusions: In the six product categories examined, substitution of added sugars for total sugars better aligned the HSR with the Australian Dietary Guidelines. Future work is required to investigate the impact in other product categories., (Copyright © 2017 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.)

High yogurt intake is associated with a reduced risk of type 2 diabetes (T2DM). Although several mechanisms could explain this association, this paper addresses the glycemic and insulinemic impact of yogurt. There is evidence that low-glycemic index (GI) and low-glycemic load (GL) diets are associated with a reduced risk of T2DM. The 93 GI values for yogurt in the University of Sydney's GI database have a mean ± SD of 34 ± 13, and 92% of the yogurts are low-GI (≤55). The 43 plain yogurts in the database have a lower GI than the 50 sweetened yogurts, 27 ± 11 compared with 41 ± 11 ( P < 0.0001). This difference is not explained by sugar, per se, but rather by the higher protein-to-carbohydrate ratio in plain yogurt. Although yogurt has a low GI, its insulinemic index (II) is higher than its GI. High insulin responses may be deleterious because hyperinsulinemia is associated with an increased risk of T2DM. Nevertheless, this may not be a concern for yogurt because, although its II is higher than its GI, the II of yogurt is within the range of II values for nondairy low-GI foods. In addition, mixed meals containing dairy protein elicit insulin responses similar to those elicited by mixed meals of similar composition containing nondairy protein. Because the GI of yogurt is lower than that of most other carbohydrate foods, exchanging yogurt for other protein and carbohydrate sources can reduce the GI and GL of the diet, and is in line with recommended dietary patterns, which include whole grains, fruits, vegetables, nuts, legumes, fish, vegetable oils, and yogurt., Competing Interests: Author disclosures: TMSW is part owner of and employed by Glycemic Index Laboratories, Inc. (GI Labs), a contract research organization. He has no financial interest in any intellectual property developed as a result of the research reported here, or of any other research conducted at GI Labs, nor any financial interest in the equity of Danone or of any other company that produces or sells food products or food ingredients. Travel expenses and an honorarium were received from Danone Institute for delivering a lecture on Fermented Dairy Intake in Relation to Glycemia and Insulinemia at the 4th International Yogurt Summit at the Experimental Biology Meeting in April 2016., (© 2017 American Society for Nutrition.)

The gut microbiota is a complex community of bacteria residing in the intestine. Animal models have demonstrated that several factors contribute to and can significantly alter the composition of the gut microbiota, including genetics; the mode of delivery at birth; the method of infant feeding; the use of medications, especially antibiotics; and the diet. There may exist a gut microbiota signature that promotes intestinal inflammation and subsequent systemic low-grade inflammation, which in turn promotes the development of type 2 diabetes. There are preliminary studies that suggest that the consumption of probiotic bacteria such as those found in yogurt and other fermented milk products can beneficially alter the composition of the gut microbiome, which in turn changes the host metabolism. Obesity, insulin resistance, fatty liver disease, and low-grade peripheral inflammation are more prevalent in patients with low α diversity in the gut microbiome than they are in patients with high α diversity. Fermented milk products, such as yogurt, deliver a large number of lactic acid bacteria to the gastrointestinal tract. They may modify the intestinal environment, including inhibiting lipopolysaccharide production and increasing the tight junctions of gut epithelia cells., Competing Interests: Author disclosures: LW and AD, no conflicts of interest., (© 2017 American Society for Nutrition.)

In previous work, we demonstrated that two probiotic strains, namely Lactobacillus casei PRA205 and Lactobacillus rhamnosus PRA331, produce fermented milks with potent angiotensin-converting enzyme (ACE)-inhibitory and antioxidant activities. Here, we tested these strains for the survivability and the release of antihypertensive and antioxidant peptides in yogurt fermentation and cold storage. For these purposes three yogurt batches were compared: one prepared using yogurt starters alone (Lactobacillus delbrueckii subspecies bulgaricus 1932 and Streptococcus thermophilus 99), and the remaining two containing either PRA205 or PRA331 in addition to yogurt starters. Despite the lower viable counts at the fermentation end compared to PRA331, PRA205 overcame PRA331 in survivability during refrigerated storage for 28 days, leading to viable counts (>10(8) CFU/g) higher than the minimum therapeutic threshold (10(6) CFU/g). Analyses of in vitro ACE-inhibitory and antioxidant activities of peptide fractions revealed that yogurt supplemented with PRA205 displays higher amounts of antihypertensive and antioxidant peptides than that produced with PRA331 at the end of fermentation and over storage. Two ACE-inhibitory peptides, Valine-Proline-Proline (VPP) and Isoleucine-Proline-Proline (IPP), were identified and quantified. This study demonstrated that L. casei PRA205 could be used as adjunct culture for producing bi-functional yogurt enriched in bioactive peptides and in viable cells, which bring health benefits to the host as probiotics., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Ayran is a traditional Turkish milk drink which is fermented and salted. Inadequate production and storage conditions contribute to its variable organoleptic quality and stability during shelf-life. A thorough physico-chemical, nutritional and microbial characterization of artisanal Ayran was carried out in order to standardize its overall quality without altering its original traits. Ayran microbial ecosystem was largely dominated by Streptococcus thermophilus (ST) and Lactobacillus delbrueckii subsp. bulgaricus (LDB). High counts of other lactic acid bacteria species, including Lactobacillus helveticus (LH), Lactobacillus fermentum (LF), and Lactobacillus paracasei (LP), were also found. Selected LDB, LP and LH strains grew well in milk displaying fast acidification and high proteolysis, differently from ST and LF strains that did not cause noticeable changes. A selected autochthonous three-strain culture (TSC), composed of one strain of LDB, LP and ST, was applied for the pilot-scale production of traditional Ayran. The Ayran produced with this TSC resulted in the most extensive shelf-life (one month) and in the best terms of its nutritional and sensory quality nevertheless altering its typical pleasant yogurt and cottage cheese notes. This TSC is at disposal of SMEs who need to standardize the overall quality of this traditional fermented milk, preserving its typical traits., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The objectives of this study were to evaluate the growth and survival of the model probiotic strain Lactobacillus plantarum WCFS1 in co-culture with traditional yoghurt starters and to investigate the impact of preculturing on their survival and metabolite formation in set-yoghurt. L. plantarum WCFS1 was precultured under sublethal stress conditions (combinations of elevated NaCl and low pH) in a batch fermentor before inoculation in milk. Adaptive responses of L. plantarum WCFS1 were evaluated by monitoring bacterial population dynamics, milk acidification and changes in volatile and non-volatile metabolite profiles of set-yoghurt. The results demonstrated that sublethal preculturing did not significantly affect survival of L. plantarum WCFS1. On the other hand, incorporation of sublethally precultured L. plantarum WCFS1 significantly impaired the survival of Lactobacillus delbrueckii subsp. bulgaricus which consequently reduced the post-acidification of yoghurt during refrigerated storage. A complementary metabolomics approach using headspace SPME-GC/MS and (1)H NMR combined with multivariate statistical analysis revealed substantial impact of sublethally precultured L. plantarum WCFS1 on the metabolite profiles of set-yoghurt. This study provides insight in the technological implications of non-dairy model probiotic strain L. plantarum WCFS1, such as its good stability in fermented milk and the inhibitory effect on post-acidification., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Yogurt and prebiotic consumption has been linked to better health. However, to our knowledge, no longitudinal study has assessed the association of yogurt and prebiotic consumption with depression risk., Objective: We longitudinally evaluated the association of yogurt and prebiotic consumption with depression risk in a Mediterranean cohort., Methods: The SUN (Seguimiento Universidad de Navarra) Project is a dynamic, prospective cohort of Spanish university graduates. A total of 14,539 men and women (mean age: 37 y) initially free of depression were assessed during a median follow-up period of 9.3 y. Validated food-frequency questionnaires at baseline and after a 10-y follow-up were used to assess prebiotic (fructans and galacto-oligosaccharide) intake and yogurt consumption (<0.5, ≥0.5 to <3, ≥3 to <7, and ≥7 servings/wk). Participants were classified as incident cases of depression when they reported a new clinical diagnosis of depression by a physician (previously validated). Multivariable Cox proportional hazards models were used to calculate HRs and 95% CIs., Results: We identified 727 incident cases of depression during follow-up. Whole-fat yogurt intake was associated with reduced depression risk: HR for the highest [≥7 servings/wk (1 serving = 125 g)] compared with the lowest (<0.5 servings/wk) consumption: 0.78 (95% CI: 0.63, 0.98; P-trend = 0.020). When stratified by sex, this association was significant only in women (HR: 0.66; 95% CI: 0.50, 0.87; P-trend = 0.004). Low-fat yogurt consumption was associated with a higher incidence of depression (HR: 1.32; 95% CI: 1.06, 1.65; P-trend = 0.001), although this association lost significance after the exclusion of early incident cases, suggesting possible reverse causation bias. Prebiotic consumption was not significantly associated with depression risk., Conclusions: Our study suggests that high consumption of whole-fat yogurt was related to a lower risk of depression in women of the SUN cohort. No association was observed for prebiotics. Further studies are needed to clarify why the yogurt-depression association may differ by fat content of the yogurt., (© 2016 American Society for Nutrition.)

During yogurt manufacture, the lactose fermentation and organic acid production can be used to monitor the fermentation process by starter cultures and probiotic bacteria. In the present work, a simple, sensitive and reproducible high-performance liquid chromatography with dual detectors, diode array detector and refractive index was validated by simultaneous analysis of carbohydrates and organic acids in goat milk yogurts. In addition, pH and bacterial analysis were performed. Separation of all the compounds was performed on an Aminex HPX-87H column (300×7.8 mm, 9 µm) utilizing a 3 mmol L(-1) sulfuric acid aqueous mobile phase under isocratic conditions. Lactose, glucose, galactose, citric, lactic and formic acids were used to evaluate the following performance parameters: selectivity, linearity, precision, limit of detection (LOD), limit of quantification (LOQ), decision limits (CCα), detection capabilities (CCβ), recovery and robustness. For the method application a six goat milk yogurts were elaborated: natural, probiotic, prebiotic, symbiotic, cupuassu fruit pulp, and probiotic with cupuassu fruit pulp. The validated method presented an excellent selectivity with no significant matrix effect, and a broad linear study range with coefficients of determination higher than 0.995. The relative standard deviation was lower than 10% under repeatability and within-laboratory reproducibility conditions for the studied analytes. The LOD of the method was defined from 0.001 to 0.003 µg g(-1), and the LOQ from 0.003 to 0.013 µg g(-1). The CCα was ranged from 0.032 to 0.943 µg g(-1), and the CCβ from 0.053 to 1.604 µg g(-1). The obtained recovery values were from 78% to 119%. In addition, the method exhibited an appropriate robustness for all parameter evaluated. Base in our data, it was concluded that the performance parameters demonstrated total method adequacy for the detection and quantification of carbohydrates and organic acids in goat milk yogurts. The application of the method was successfully applied to monitoring different goat milk yogurts during fermentation., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background & Aims: Especially in older adults, maintaining muscle mass is essential to perform activities of daily living. This requires a sufficient protein intake. However, protein intake in hospitalized older adults is often insufficient. Thus far different nutrition intervention strategies have failed to show success in reaching sufficient protein intake in hospitalized older adults. The effect of recently developed protein-enriched bread and drinking yoghurt on protein intake is still unknown. Therefore, the objective of this study was to examine the effect of protein-enriched bread and drinking yoghurt on the protein intake of acute hospitalized older adults (≥55 years)., Methods: This study was performed as a single blind randomized controlled trial in 47 hospitalized elderly acutely admitted to a university hospital. During three consecutive days participants received either ad libitum protein-enriched bread and drinking yoghurt or normal, non-enriched products as part of their daily meals. The protein-enriched bread contained 6.9 g of protein per serving and the normal bread 3.8 g of protein. For drinking yoghurt this was 20.0 g and 7.5 g of protein per serving respectively. The products were almost isocaloric. Food intake of participants was measured and nutritional values were calculated according to the Dutch Food Composition Table. An independent sample t-test was used to compare protein intake between the intervention and control group., Results: Analyses illustrate a protein intake in the intervention group of 75.0 ± 33.2 g per day versus 58.4 ± 14.5 g in the control group (p = 0.039). Intervention patients had a mean protein intake of 1.1 g/kg/day, with 36% of the patients reaching the minimum requirement of 1.2 g/kg/day; in control patients this was 0.9 g/kg/day (p = 0.041) and 8% (p = 0.030). Bread and drinking yoghurt contributed almost equally to the increased intake of protein in the intervention group., Conclusions: The use of protein-enriched bread and drinking yoghurt, consumed as part of regular meals, is a promising and feasible solution to increase the protein intake of acutely ill patients. It needs to be confirmed whether the use of these products will also result in a better clinical outcome. ClinicalTrials.gov ID number: NCT01907152., (Copyright © 2014 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

A new and sensitive determination method was developed for bovine lactoferrin in dairy products including infant formulas based on the signature peptide by ultra high-performance liquid chromatography and triple-quadrupole tandem mass spectrometry under the multiple reaction monitoring mode. The simple pretreatment procedures included the addition of a winged peptide containing the isotope-labeled signature peptide as internal standard, followed by an enzymatic digestion with trypsin. The signature peptide was chosen and identified from the tryptic hydrolyzates of bovine lactoferrin by ultra high-performance liquid chromatography and quadrupole-time-of-flight tandem mass spectrometry based on sequence database search. Analytes were separated on an ACQUITY UPLC BEH 300 C18 column and monitored by MS/MS in seven minutes. Quantitative result bias due to matrix effect and tryptic efficiency was corrected through the use of synthetic isotope-labeled standards. The limit of detection and limit of quantification were 0.3 mg/100 g and 1.0 mg/100 g, respectively. Bovine lactoferrin within the concentration range of 10-1000 nmol L(-1) showed a strong linear relationship with a linear correlation coefficient (r) of >0.998. The intra- and inter-day precision of the method were RSD<6.5% and RSD<7.1%, respectively. Excellent repeatability (RSD<6.4%) substantially supported the application of this method for the determination of bovine lactoferrin in dairy samples. The present method was successfully validated and applied to determination of bovine lactoferrin in dairy products including infant formulas., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A new method based on dispersive liquid-liquid microextraction (DLLME) followed by high-performance liquid chromatography (HPLC) for determination of benzoate and sorbate salts in yogurt drinks was developed. The effective parameters in DLLME process, including volume of extraction and disperser solvents, pH and salt effect, were optimized using response surface methodology (RSM) based on central composite design. The yogurt drink samples were extracted using NaOH and Carrez solutions (potassium hexaferrocyanide and zinc acetate) were used for sedimentation of proteins. For DLLME, a mixture of extraction solvent (1-octanol) and disperser solvent (ethanol) was rapidly injected into the sample solution by syringe and cloudy solution is formed. Subsequently, the upper 1-octanol layer was analyzed by HPLC. The detection limits for benzoate and sorbate were 0.06 ng mL(-1) and 0.15 ng mL(-1), respectively. The relative standard deviations (RSD) for seven analyses were 4.96% for benzoate and 4.58% for sorbate. The proposed method demonstrated good linearity and high enrichment factor. A clean separation and good chromatogram is readily achieved without the presence of matrix interference. A comparison of this method with previous methods demonstrated that the proposed method is an accurate, rapid and reliable sample-pretreatment method that gives very good enrichment factors and detection limits for extracting and determining sorbate and benzoate in yogurt drink samples., (Copyright © 2013 Elsevier B.V. All rights reserved.)

This study was conducted to investigate the occurrence of aflatoxin M1 (AFM1) in milk products in China using the competitive enzyme-linked immunosorbent assay method and to estimate the dietary exposure to this toxin through a probabilistic approach. Based on the exposure assessment results, a quantitative cancer potency formula developed by the Joint Food and Agriculture Organization and World Health Organization Expert Committee on Food Additives was applied to assess the cancer risk. AFM1 was detected in 48.07% of the milk samples and 4.49% of the yoghurt samples. No samples contained AFM1 above the current regulatory limit in China. The simulated AFM1 intake (90% confidence interval) in various sex-age groups ranged from 0.023 (0.021 to 0.023) ng/kg of body weight per day for 30- to 45-year-old men to 0.382 (0.354 to 0.386) ng/kg of body weight per day for 2- to 4-year-old girls at the 99th percentile. The cancer risk of AFM1 to the general population of China was assessed to be 0.129 cancer cases per year per 10(8) persons at the 99th percentile. These results indicate that the health risk associated with AFM1 in milk in China is relatively low.

In this study we used micro liquid chromatography coupled to time-of-flight mass spectrometry (microLC-TOF-MS) for separation and identification of bioactive peptides in a yogurt marketed as an antihypertensive functional food. An appropriate sample clean-up using solid-phase extraction (SPE) allowed detection of a large number of low-molecular-mass bioactive peptides by reversed-phase microLC-TOF-MS. The preliminary identification was solely based on the experimental monoisotopic molecular mass values (M(exp)). Later, we evaluated the correlations between predicted normalized elution time (NET) and experimental normalized retention times (t(r)') values to describe the retention behavior of the proposed sequences. The assistance of retention prediction proved to be useful to improve reliability of the identification, avoiding misinterpretations and solving some identity conflicts. After revision, the identity of only fifty bioactive peptides was confirmed. Significant number of these peptides was reported as angiotensin converting enzyme (ACE) inhibitors and nine of them were antihypertensive. The presence of peptide sequences with other biological activities such as antibacterial, antithrombotic, antioxidant, cell modulation, immune or phagocytosis stimulation, epitopes of B cells and opioid agonists was also confirmed., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The ionic liquid foaming-based solvent floatation (ILF-SF) was developed for extracting triazines and phenylureas from yogurt. These analytes were separated and determined by high performance liquid chromatography. Some experimental parameters, such as the pH value of floatation solution, extraction solvent, kind of ionic liquid and floatation time were investigated and optimized. The mixture of n-propyl alcohol and ethyl acetate was used as extraction solvent and 1-hexyl-3-methylimidazolium hexafluorophosphate was used as foaming agent. The precision and recoveries of eight herbicides vary from 0.17 to 6.90% and from 86.5 to 118.7%, respectively. The detection limits for simeton, simazine, chlortoluron, isoproturon, ametryn, propazine, prometryne and prebane are 0.59, 0.44, 0.44, 0.46, 0.32, 1.01, 0.34 and 0.23 μgL(-1), respectively. The enrichment factors for the solvent floatation range from 11.6 to 18.6 for the eight herbicides., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Herein, a novel sensitive electrochemical sensor for copper(II) based on Cu(I) catalyzed alkyne-azide cycloaddition reaction (CuAAC) is described. The catalyst of Cu(I) species is derived from electrochemical reduction of Cu(II) through bulk electrolysis (BE) with coulometry technique. The propargyl-functionalized ferrocene (propargyl-functionalized Fc) is covalently coupled onto the electrode surface via CuAAC reaction and forms propargyl-functionalized Fc modified gold electrode, which allows a good and stable electrochemical signal. The change of current at peak (dI), detected by differential pulse voltammetry (DPV), exhibits a linear response to the logarithm of Cu(II) concentration in the range of 1.0×10(-14)-1.0×10(-9) mol L(-1). It is also found that the proposed sensor has a good selectivity for copper(II) assay even in the presence of other common metal ions. Additionally, the proposed method has been applied to determine copper(II) in the dairy product (yoghurt) with satisfactory results., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The aggregation and adhesion of bacterial cells is a serious disadvantage for electrophoretic separations of bacteria. In this study, lipid-based liquid crystalline nanoparticles were used as a pseudostationary phase to minimise the bacterial aggregation and adsorption to the inner walls of microchannels. Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus and Lactobacillus rhamnosus were selected as analytes and were separated by microchip electrophoresis (MCE) with laser-induced fluorescence (LIF) detection using 4.5 mM tris(hydroxymethyl) aminomethane (TRIS)-4.5 mM boric acid-0.1 mM ethylenediaminetetraacetate (EDTA) (TBE) containing poly(ethylene oxide) (PEO) and lipid-based nanoparticles as the running buffer. The mechanism of lipid-based nanoparticles affecting bacterial adhesion and aggregation was discussed and supported by zeta potential experiments. Under the optimal conditions, the three species of bacteria were identified with patterned peaks. This proposed MCE method using lipid-based nanoparticles as running buffer additives was also used to analyse a real yogurt sample, and valuable bacterial information was obtained by the electropherograms., (Copyright © 2011 Elsevier B.V. All rights reserved.)

In the work presented here a novel approach to comprehensive two-dimensional liquid chromatography is evaluated. Ion chromatography is chosen for the first-dimension separation and reversed-phase liquid chromatography is chosen for the second-dimension separation mode. The coupling of these modes is made possible by neutralising the first-dimension effluent, containing KOH, prior to transfer to the second-dimension reversed-phase column. A test mixture of 24 low-molar-mass organic acids is used for optimisation of the system. Three food and beverage samples were analysed in order to evaluate the developed methodology, the resulting two-dimensional separation is near-orthogonal, the set-up is simple and all instrumental components are available commercially. The method proved to be robust and suitable for the analysis of wine, orange juice and yogurt., (Copyright © 2010 Elsevier B.V. All rights reserved.)

A liquid chromatography with diode array detection coupled to dual electrospray atmospheric pressure chemical ionization time-of-flight mass spectrometry (HPLC/ESI-APCI-TOF-MS) method is described for the rapid determination of five monophosphate nucleotides (cytidine 5'-monophosphate, uridine 5'-monophosphate, adenosine 5'-monophosphate, inosine 5'-monophosphate and guanosine 5'-monophosphate) in baby foods. The method is based on the deproteinisation of foods and direct analysis of nucleotides by ion-pair HPLC using isocratic elution with a mobile phase of 5% (v/v) methanol and 95% (v/v) 0.1 M formate buffer (pH 5.5) containing 0.01 M N,N-dimethylhexylamine (DMHA) at a flow-rate of 0.7 mL min(-1). The HPLC was hyphenated with two different detection systems, photodiode-array (DAD) and ESI-APCI-TOF-MS in negative mode. The method was validated for linearity, detection and quantitation limits, selectivity, accuracy and precision. The recoveries obtained for spiked samples were satisfactory for all the analytes. The method was successfully applied to the analysis of nucleotides in different baby and/or functional food samples, as cereals, purees and dairy products. A study was also carried out on the stability of nucleotides in acidified dairy infant food with pasteurized yoghourt and follow-on formulae samples stored at room temperature and at 30 degrees C., (Copyright 2010 Elsevier B.V. All rights reserved.)

This paper presents an analytical procedure for the direct determination of zinc in yogurt employing sampling slurry and high resolution-continuum source flame atomic absorption spectrometry (HR-CS FAAS). The step optimization established the experimental conditions of: 2.0molL(-1) hydrochloric acid, a sonication time of 20min and a sample mass of 1.0g for a slurry volume of 25mL. This method allows the determination of zinc with a limit of quantification of 0.32microgg(-1). The precision expressed as relative standard deviation (RSD) were 0.82 and 2.08% for yogurt samples containing zinc concentrations of 4.85 and 2.49microgg(-1), respectively. The accuracy was confirmed by the analysis of a certified reference material of non-fat milk powder furnished by the National Institute of Standard and Technology. The proposed method was applied for the determination of zinc in seven yogurt samples. The zinc content was varied from 2.19 to 4.85microgg(-1). These results agreed with those reported in the literature. The samples were also analyzed after acid digestion and zinc determination by FAAS. No statistical difference was observed between the results obtained by both of the procedures performed.

This research was conducted to examine the inherent properties of yogurt contaminated with staphylococcal enterotoxin B (SEB). Two types of yogurts were produced for this study. Type I yogurts were produced by adding SEB at the start of yogurt production, and type II yogurts were produced by adding SEB after the milk base had been boiled. Biochemical characteristics inherent to yogurt, including pH, lactic acid and acetaldehyde concentrations, were analyzed weekly for each batch beginning at a time just after production and throughout a storage period of at least 4 weeks. The presence of toxin during yogurt production did not result in any significant biochemical or physical changes in yogurt. However, we were unable to detect SEB toxin in type I yogurt using a commercially available enzyme-linked immunosorbent assay (ELISA). In contrast, SEB was easily detectable by our ELISA in type II yogurt samples. Higher levels of SEB were recovered from type II yogurt that had been stored for 1 week than from type II yogurt that had been stored for any other length of time. These results indicate that the biochemical characteristics of yogurt did not change significantly (relative to control yogurt) in the presence of either thermally processed SEB or native SEB. However, the ability to detect SEB by ELISA was dependent on whether the toxin had been processed.

Enumeration of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus is a priority due to their importance in yogurt production. Capillary electrophoresis (CE) of both bacteria could be achieved in 7.2 min with a resolution of 3.2 in the background electrolyte (BGE) containing 4.5mM Tris(hydroxymethyl) amminomethane (TRIS)-4.5 mM boric acid-0.1 mM ethylenediamine tetraacetate (EDTA) (TBE) buffer (pH 8.4) and 0.05% (v/v) polyethylene oxide (PEO), using a capillary of 47.5 cm (effective length) x 100 microm i.d., injection of 50 mbar x 3s followed by -5kV x 120s, a voltage and temperature of 20 kV and 25 degrees C, respectively. Appropriate amounts of PEO in the BGE, sample preparation (i.e. vortex) and introduction were key factors for their separation. A short hydrodynamic injection followed by applying reversed polarity voltage could compress the bacteria into narrow zones, which were detected as separated single peaks. Method linearity (r(2)>0.99), precision (%RSDs<9.3%), recovery (%R=91.7-106.7%) and limit of quantitation (1.0 x 10(6) colony forming unit per mL (CFU/mL)) were satisfactory. Results from the CE analysis of both bacteria in yogurt were not statistically different from those of the plate count method (P>0.05). The CE method can be used as an alternative for quantitation of L. delbrueckii subsp. bulgaricus and S. thermophilus in yogurt since it was reliable, simple, cost and labor effective and rapid, allowing the analysis of 3 samples/h (comparing to 2d/sample by plate count method).

A new chemiluminescence-based one-shot biosensor for lactate is described. The lactate recognition system is based on lactate oxidase (LOx) and the transduction system consists of luminol, peroxidase from Arthromyces ramosus (ARP) and metallic aluminum, all immobilized in a polyion complex membrane. The measurement of the chemiluminescence in a luminometer when 1 mL of sample is injected into a conventional cell containing the disposable sensing membrane makes it possible to determine lactate. The compositions of the membrane and reaction conditions have been optimized to obtain adequate sensitivity. The one-shot biosensor responds to lactate rapidly, with the typical CL acquisition time being 2 min, with a linearized logarithmic dependence whose dynamic range was from 5 x 10(-5) to 4 x 10(-3) with a detection limit of 9.2 x 10(-6)M and a sensor-to-sensor reproducibility (relative standard deviation, R.S.D.) of 5.5% at the medium level of the range. The performance of the chemiluminescent one-shot biosensor was tested for the analysis of lactate in yoghurt, validating the results against an enzymatic reference procedure. The proposed method is quick, inexpensive and sensitive and uses conventional CL instrumentation.

The aim of this work was to devise a novel fully computerised chromatography-olfactometry system where eight sniffers detect volatile compounds obtained from a single chromatographic separation. The technical options taken to implement this system are described in detail. The new methods and software developed and applied to analyse data obtained by gas chromatography-olfactometry and mass spectrometry (GC-O/MS) are presented. We found that 46 odorous zones could be detected by a panel of eight sniffers during the 35min of the analysis of the volatile compounds extracted from a cheese by purge-and-trap. Synchronisation of olfactometry and mass spectrometry data enabled us to propose 44 structures to account for 44 out of these 46 odorous zones.

A vanguard/rearguard analytical strategy for the monitoring of the degradation of yoghurt samples is proposed. The method is based on the headspace-gas chromatography-mass spectrometry (HS-GC-MS) instrumental coupling. In this combination, the chromatographic column is firstly used as an interface between the HS and the MS (vanguard mode) avoiding separation of the volatile components by maintaining the chromatographic oven at high, constant temperature. By changing the thermal conditions of the oven, the aldehydes can be properly separated for individual identification/quantification (rearguard mode). In the vanguard method, the quantification of the volatile aldehydes was calculated through partial least square and given as a total index. The rearguard method permits the detection of the aldehydes at concentrations between 12 and 35 ng/g. Both methods were applied to the study of the environmental factors favouring the presence of the volatile aldehydes (C(5)-C(9)) in the yoghurt samples. Principal component analysis of the total concentration of aldehydes with the time (from 0 to 30 days) demonstrates the capability of the HS-MS coupling for the estimation of the quality losses of the samples. The results were corroborated by the HS-GC-MS which also indicates that pentanal was present in the yoghurt from the beginning of the study and the combination of light/oxygen was the most negative influence for sample conservation.

Total resolution of 17 DL-amino acids after derivatization with a fluorescent chiral tagging reagent, 4-(3-isothiocyanatopyrrolidin-1-yl)-7-(N,N-dimethylaminosulfony l)-2,1,3- benzoxadiazole [R(-)-DBD-PyNCS], was studied by reversed-phase liquid chromatography. The reaction of the reagent with amino acids proceeds effectively at 55 degrees C for 20 min in the presence of 1% TEA to produce the corresponding fluorescent diastereomers (excitation at 460 nm, emission at 550 nm). Each pair of the resulting derivatives was efficiently separated with water-acetonitrile containing 1% acetic acid as the mobile phase. Peak resolution was in the range of 0.92 (DL-Arg)-9.8 (DL-Cys). Although mutual separation of some DL-amino acids was possible using the elution solvent, simultaneous resolution of 17 DL-amino acids was difficult with a single chromatographic run, even if some gradient elutions were adopted. Therefore, both gradient and isocratic elution systems were used for total resolution of the DL-amino acids. Thus, 17 DL-amino acids were well resolved by a gradient and an isocratic elution systems. The proposed derivatization and elution methods were applied to the determination of DL-amino acids in yogurt. The results showed that some of the L-amino acids, i.e., Glu, Asp, Ser, Gly, Ala, Thr, Pro, Lys, Phe and Met, were found in the methanol extracts of yogurt. On the other hand, the D-amino acids that were identified in the extracts were D-Glu, D-Asp and D-Ala, and the mean % to each L-amino acid were 11.9% (D-Glu), 27.6% (D-Asp) and 56.7% (D-Ala), respectively.

During 1995, 159 samples of milk, 97 samples of dry milk for infant formula, and 114 samples of yogurt were randomly collected in supermarkets and drug stores in four large Italian cities and checked for aflatoxin M1 (AFM1) by immunoaffinity column extraction and HPLC. AFM1 was detected in 136 (86%) of the milk samples (in amounts ranging from < 1 ng/liter to 108.5 ng/liter; mean level: 10.19 ng/liter), in 81 (84%) of the dry milk samples (in amounts ranging from < 1 ng/liter to 101.3 ng/kg; mean level: 21.77 ng/kg), and in 91 (80%) of the yogurt samples (in amounts ranging from < 1 ng/liter to 496.5 ng/liter; mean level: 18.08 ng/liter). Altogether, only two samples of milk, two samples of yogurt, and one sample of dry milk had levels of AFM1 exceeding the Swiss legal limits, which are the most restrictive in the world. AFM1 contamination levels in milk and yogurt samples collected in the period of November to April were ca. four times as high as those in samples collected in the period of May to October. It is concluded that during 1995, despite the widespread occurrence of AFM1, the mean contamination levels in dairy products sold in Italy were not a serious human health hazard.

The effect of different concentrations of sugars in two foods (strawberry yoghurt and baked beans) on plaque acidogenicity was investigated using plaque sampling with a 'Beetrode' electrode. Six varieties of yoghurt, four varieties of baked beans and positive and negative control solutions of 10 per cent sucrose and sorbitol, respectively, were tested on six volunteers, selected according to the guidelines agreed at the San Antonio Conference of 1985. Plaque was harvested immediately before a one minute challenge with the test condition and at 5, 10, 15, 20 and 30 minutes thereafter. Parameters investigated were minimum plaque pH reached after a one minute consumption/rinse of the test food or control solution, maximum drop in plaque pH and 'area of the Stephan curve below pH 6.5'. An Acidogenic Potential Index was calculated for each test food and the results did not suggest a linear relationship between sucrose concentration in a food and acidogenic potential.

An analytical method to detect and quantitate neohesperidine dihydrochalcone in foodstuffs has been developed and validated in soft-drink applications. The method was shown to be sufficiently precise, accurate, selective and rugged in quantitating neohesperidine DC both at flavouring (1-5 mg/kg) and sweetening (5-50 mg/kg) levels. Applications of the method to determine neohesperidine DC in foodstuffs other than soft-drinks is also described.

Stable isotopes were used to compare calcium fractional absorption from intrinsically and extrinsically labeled bovine milk as well as intrinsically labeled dairy product and cheese analogue. Healthy Caucasian women were fed a controlled diet for 4 d during the follicular phase of their menstrual cycle. With breakfast on the third day, participants ingested milk containing 44Ca (intrinsic) and 42CaCl2 (extrinsic) or dairy products containing 44Ca. Total feces were collected for 2 d prior to and 10 d after isotope ingestion. Polyethylene glycol was administered to monitor completeness of fecal collections. Total calcium was determined by atomic absorption spectrophotometry, and isotopic abundance was determined by high resolution fast atom bombardment mass spectrometry. Fractional absorption was determined as the difference between the administered isotopic dose and the quantity of 44Ca or 42Ca excreted in feces. The fractional absorption of calcium from milk was not affected by the method of labeling, lactose content, fermentation or the chemical form of calcium in dairy products or cheese analogue.

We describe here the isolation and identification of palmitic acid as being responsible for significant anti-N-methyl-N'-nitro-N-nitroguanidine (MNNG) activity in yogurt. The Ames test (Salmonella typhimurium TA100) was used to direct fractionation of activity. Yogurt was freeze-dried and extracted with acetone to yield a crude extract. The crude extract was purified by normal phase silica gel, Sephadex LH-20, and reversed phase medium pressure liquid chromatographies. The major compound in the active medium pressure liquid chromatographic fractions was determined to be palmitic acid on GC and high pressure liquid chromatography (HPLC) systems, and by nuclear magnetic resonance (NMR) analysis. Other saturated straight chain and methyl branched fatty acids were detected by GC/MS and were later shown to possess anti-MNNG activity. Of the straight chain fatty acids, palmitic acid had the highest anti-MNNG activity. All omega - 1 methyl branched fatty acids tested were more active than their straight chain counterparts. A trace amount of isopalmitic acid (14-methyl pentadecanoic acid), a minor milk lipid, was detected in one of the active fractions, and was later shown to be five times more active than palmitic acid. Isopalmitic acid also inhibited mutagenesis induced 4-nitroquinoline-N-oxide (4NQO), and 7, 12-dimethyl benz[a]anthracene (DMBA), and was found to inhibit the metabolic activation of DMBA.

Yogurt is milk fermented by a mixture of two bacteria: Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus. Epidemiological studies have correlated a reduced risk of colon cancer with yogurt consumption. Independent studies have established that yogurt and extracts thereof are antimutagenic. Although multiple explanations can account for yogurt's putative anticarcinogenicity, we are interested in testing the hypothesis that antimutagenic compounds produced during fermentation are responsible. We recently reported on the antimutagenicity of an acetone extract of yogurt against the experimental carcinogens N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and 3.2'dimethyl-4-aminobiphenyl (DMAB) (Mutation Res. (1995) 334, 213-224). We are now aware that palmitic acid is an active ingredient against MNNG.

Objective: This study tested the hypothesis that the perceived fat content of a preload (a required first course) influences subsequent food and energy intake., Subjects and Design: Forty-eight healthy, nondieting women (24 restrained, 24 unrestrained) were given a fixed amount (350 g) of three different yogurts (low-fat, low-calorie; low-fat, high-calorie; high-fat, high-calorie), or no yogurt, followed by lunch (30 minutes after the yogurt preload was served) and dinner (4.5 hours later). Each subject was tested in all four conditions in a counterbalanced design. Half of the subjects received accurate information, in the form of a label, about the fat content of the yogurts, which did not necessarily correspond to energy content; the other half received no information., Analyses: Energy intake, the percentage of macronutrients in the meals, and subjective sensations of hunger and satiety were analyzed., Results: No effect of restraint was noted in the intake analyses. A significant information-by-preload interaction (P < .05) was found. Subjects who had information consumed more energy at lunch after eating a preload labeled low fat than after eating a preload with similar energy content but labeled high fat. The opposite response was seen in women who did not receive information. When energy consumed at dinner was included in the analyses, overall intake was still significantly greater in the women who received information and ate a low-fat preload. No differences were found in the percentage of macronutrients selected or in subjective sensations after consumption of any of the preloads., Conclusions: Messages about the fat content of a food can influence energy intake in healthy women.

Reconstituted non-fat dry milk powder, fermented by a mixture of Streptococcus thermophilus CH3 and Lactobacillus bulgaricus 191R to produce yogurt, was freeze-dried and extracted in acetone. After evaporation of the acetone, the extract was dissolved in dimethyl sulfoxide (DMSO) and tested for antimutagenicity. In the Ames test, significant dose-dependent activity was observed against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 4-nitro-quinoline-N-oxide (4NQO), 3,2'-dimethyl-4-aminobiphenyl (DMAB), 9,10-dimethyl-1,2-benz[a]anthracene (DMBA), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole acetate (Trp-P-2). Weak activity was observed against 1,2,7,8-diepoxyoctane (DEO), and no activity was observed against methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), or aflatoxin B1 (AFB1). In a related assay (Saccharomyces cerevisiae D7), significant antimutagenic activity was detected against MNNG and 4NQO. Activity against the experimental colon carcinogens MNNG and DMAB was examined further, as assayed in the Ames test (Salmonella typhimurium TA100). Compounds responsible for both activities were less soluble in aqueous solutions than in DMSO. Adjustment of yogurt pH to 3, 7.6, or 13 prior to freeze-drying and acetone extraction did not significantly alter the amount of anti-MNNG activity recovered. In contrast, extractability of anti-DMAB activity was significantly greater at acidic pH. Conjugated linoleic acid, a known dairy anticarcinogen, failed to inhibit mutagenesis caused by either mutagen, suggesting that other yogurt-derived compound(s) are responsible. Unfermented milk was treated with lactic acid, yogurt bacteria without subsequent growth, or both, to determine if formation of antimutagenic activity required bacterial growth. Extracts of the milk treatments exhibited the same weak antimutagenicity observed in unfermented milk, approximately 2.5-fold less than in the yogurt extracts, suggesting that antimutagenic activity is associated with bacterial growth.

Lactose in yogurt with live bacteria is better tolerated than lactose in other dairy foods, partly because of the activity of microbial beta-galactosidase (beta-gal), which digests lactose in vivo. To evaluate the ability of different strains and species of lactic acid bacteria to digest lactose in vivo, yogurts (containing mixtures of strains of Streptococcus salivarius subsp thermophilus and Lactobacillus delbrueckii subsp bulgaricus) and fermented milks (containing individual species of S thermophilus, L bulgaricus, L acidophilus, or Bifidobacterium bifidus) that varied in microbial beta-gal activity were produced. Selected products were fed to healthy people who cannot digest lactose, and breath hydrogen production was monitored. All yogurts dramatically and similarly improved lactose digestion, regardless of their total or specific beta-gal activity. The response to fermented milks varied from marginal improvement with B bifidus milk to nearly complete lactose digestion with L bulgaricus milk. The results suggest that total beta-gal was not the limiting factor in promoting lactose digestion, perhaps because of a limited rate of intracellular substrate transport.

A procedure for the simultaneous determination of both ascorbic and dehydroascorbic acid in dairy foods by high-performance liquid chromatography using precolumn derivatization with 4-methoxy- and 4-ethoxy-1,2-phenylenediamine is presented. The derivatives are isolated by solid-phase extraction and analysed by fluorescence detection on a resin-type reversed-phase column at pH 9. Retention times are 2 and 3.2 min for the derivatives of ascorbic and dehydroascorbic acid, respectively. Relative standard deviations of the within- and between-assay tests are 7.1 and 5.5%, respectively, for ascorbic and 11 and 9%, respectively, dehydroascorbic acid. The limits of detection are 50 and 70 fmol per 5-microl injection for ascorbic and dehydroascorbic acid, respectively.