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Summary: The lignan from milled defatted flaxseed powder (DFP) and defatted hull powder (DHP) was extracted using direct alkaline hydrolysis and the quantity of lignan in the extract was estimated to be in the range of 11.74–14.30 mg g−1 flaxseed on a dry matter basis. Qualitative and quantitative analysis of different strains of Lactiplantibacillus plantarum (A1, Lp9, A5) along with yogurt mix culture (NCDC 146), Streptococcus salivarius ssp. thermophilus (NCDC 74) and Lactobacillus delbrueckii ssp. bulgaricus (NCDC 253) revealed that NCDC 74/A5 and NCDC 146/A5 co‐cultures are the most compatible. Buffalo milk containing different concentrations of lignan (100–400 mg of SDG/100 mL milk) was subjected to a fermentation dynamics study. The study revealed that the fermentation dynamics of Lactiplantibacillus plantarum in the milk did not get affected by starter cultures and flaxseed lignan. The results of this study could be useful in developing functional fermented probiotic milk products containing flaxseed lignan. [ABSTRACT FROM AUTHOR]

Purpose: We investigated the association between an increased intake of one dairy product subgroup at the expense of another within a 5-year period and the subsequent 10-year risk of type 2 diabetes. Methods: The cohort included 39,393 adults with two measurements of diet assessed using food frequency questionnaires (FFQ) administered in 1993–1997 and 1999–2003. Dairy products were milk (skimmed, semi-skimmed, whole fat), buttermilk, low-fat yogurt, whole-fat yogurt, cheese and butter. Type 2 diabetes cases were ascertained from the Danish National Diabetes Register. The pseudo-observation method was used to calculate risk differences (RD) with 95% confidence intervals (CI). The data were analysed in age strata to fulfil the assumption of independent entry. Results: Among participants aged 56–59 years at completion of the follow-up FFQ, increased intake of whole-fat yogurt in place of skimmed, semi-skimmed or whole-fat milk was associated with a reduced risk (RD% [95% CI]: − 0.8% [− 1.3, − 0.2]; − 0.6% [− 1,1, − 0.1]; − 0.7 [− 1.2, − 0.1]; per 50 g/d, respectively). Among participants aged 60–64 and 65–72, substitution of skimmed milk for semi-skimmed milk was associated with an increased risk of type 2 diabetes (0.5% [0.2, 0.7]; 0.4% [0.1, 0.7]; per 50 g/d, respectively). Similar patterns of associations were found after adjustment for potential mediators. Conclusion: Our results suggest that substitution of whole-fat yogurt for milk among those aged 56–59 decreases risk of type 2 diabetes and substitution of skimmed milk for semi-skimmed milk may increase the risk among those aged 60–64 and 65–72. [ABSTRACT FROM AUTHOR]

Skyr yogurts have been gaining prominence because of their different sensory characteristics. Due to their healthy appeal, the use of natural sweeteners to replace sucrose in this type of yogurt can be an alternative for incorporating a sweet taste, in addition to increasing the functionality of the product through the incorporation of prebiotics. This study aimed to determine whether the addition of fructooligosaccharide (FOS), sucrose, stevia, and thaumatin affects the sensory profile of the skyr yogurt with mango pulp and its acceptance in two Brazilian regions. Eight formulations of skyr with mango pulp were developed. The compositional parameters evaluated were moisture, protein, lipids, ash, and carbohydrate. The tests performed were ideal sweetness and mango flavor, sweetness equivalence for each sweetener used, Quantitative Descriptive Analysis (QDA), and consumer testing in the Southeast and Northeast regions of Brazil. In general, the addition of FOS did not impact the characteristics of the formulated skyr yogurt. The type of sweetener had an impact on the sensory profile and acceptance of the skyr yogurt, affected characteristics such as mango flavor, sweet taste, sweet aftertaste, bitter taste, bitter aftertaste, and metallic flavor. The results of the affective test demonstrated that, for consumers in the Southeast, mango flavor is a positive attribute in this yogurt, and for Northeastern consumers, in addition to mango flavor, sweetness must also be taken into consideration. Practical Application: This study may be useful for the dairy industry because in the literature, there is still a lack of sensory studies of skyr yogurt, especially when sucrose substitutes are used. The results of the consumer test in this work reinforce the importance of studies related to consumer preferences with cultural differences. [ABSTRACT FROM AUTHOR]

The antioxidant potential (AP) is an important nutritional property of foods, as increased oxidative stress is involved in most diet-related chronic diseases. In dairy products, the protein fraction contains antioxidant activity, especially casein. Other antioxidants include: antioxidant enzymes; lactoferrin; conjugated linoleic acid; coenzyme Q10; vitamins C, E, A and D3; equol; uric acid; carotenoids; and mineral activators of antioxidant enzymes. The AP of dairy products has been extensively studied in vitro, with few studies in animals and human subjects. Available in vivo studies greatly differ in their design and objectives. Overall, on a 100 g fresh weight-basis, AP of dairy products is close to that of grain-based foods and vegetable or fruit juices. Among dairy products, cheeses present the highest AP due to their higher protein content. AP of milk increases during digestion by up to 2·5 times because of released antioxidant peptides. AP of casein is linked to specific amino acids, whereas β-lactoglobulin thiol groups play a major role in the AP of whey. Thermal treatments such as ultra-high temperature processing have no clear effect on the AP of milk. Raw fat-rich milks have higher AP than less fat-rich milk, because of lipophilic antioxidants. Probiotic yoghurts and fermented milks have higher AP than conventional yoghurt and milk because proteolysis by probiotics releases antioxidant peptides. Among the probiotics, Lactobacillus casei/acidophilus leads to the highest AP. The data are insufficient for cheese, but fermentation-based changes appear to make a positive impact on AP. In conclusion, AP might participate in the reported dairy product-protective effects against some chronic diseases. [ABSTRACT FROM AUTHOR]

Lactobacillus delbrueckii subspecies are important microorganisms for cheese or yogurt production, and timely and effective monitoring is required to improve dairy product quality. In this study, an ultrafast polymerase chain reaction (PCR) assay with a microfluidic device was developed to detect three L. delbrueckii subspecies, namely L. delbrueckii subsp. bulgaricus , L. delbrueckii subsp. delbrueckii , and L. delbrueckii subsp. lactis , in pure culture and spiked milk samples without the need for complicated genomic DNA isolation. Based on genetic markers derived from comparative genomics, primer pairs for the identification of the subspecies were designed. The specificity of the primer pairs was confirmed using 65 reference strains. In pure culture and milk samples, this assay exhibited sensitivity of 1 × 102 CFU/ml. Twenty-nine probiotic or dairy products were evaluated to confirm the applicability of direct ultrafast PCR assay with a simple lysis step. The developed assay enabled the rapid identification and quantification of L. delbrueckii subspecies in foods from sampling to results within 30 min. Therefore, our assay might be applied as a convenient portable system for the on-site detection of L. delbrueckii subspecies in the dairy industry. • Ultrafast PCR assay was developed for on-site monitoring of L. delbrueckii subspecies. • The genetic markers obtained from pangenome analysis showed high specificity. • The detection limit of ultrafast PCR assay is 1 × 102 CFU/ml. • This assay takes only 30 min to detect three L. delbrueckii subspecies in foods. [ABSTRACT FROM AUTHOR]

The concentration of n-3 polyunsaturated fatty acids (PUFA) in yogurt was increased using 5 different vegetable oils obtained from flaxseed, Camelina sativa, raspberry, blackcurrant, and Echium plantagineum. The vegetable oils were added to partially skim milk before lactic fermentation at a concentration adequate enough to cover at least 10% of the recommended daily intake of 2 g/d of α-linolenic acid according to EC regulation no. 432/2012. Microbiological (lactobacilli and streptococci, yeast, and molds), chemical (pH, syneresis, proximate composition, fatty acids, oxidation stability), and sensory evaluations were assessed for all of the fortified yogurts after 0, 7, 14, and 21 d of storage at 4°C. Sensory evaluations were conducted at 21 d of storage at 4°C. Among the yogurts produced, those that were supplemented with flaxseed and blackcurrant oils exhibited the highest α-linolenic acid content (more than 200 mg/100 g of yogurt) at the end of storage. The addition of oil did not influence the growth of lactic acid bacteria that were higher than 107 cfu/g at 21 d of storage. All of the yogurts were accepted by consumers, except for those supplemented with raspberry and E. plantagineum oils due to the presence of off flavors. [ABSTRACT FROM AUTHOR]

For manufacture of commercial yogurt powder, yogurt has to go through a drying process, which substantially lowers the yogurt culture counts, so the potential health benefits of the yogurt culture bacteria are reduced. Also, upon reconstitution, commercial yogurt powder does not taste like yogurt and has an off-flavor. The objective was to study the microbial, physicochemical, and sensory characteristics of reconstituted yogurt from yogurt cultured milk powder (YCMP) mix and reconstituted yogurt from commercial yogurt powder (CYP). The CYP reconstituted yogurt was the control and YCMP mix reconstituted yogurt was the treatment. Microbial and physicochemical characteristics of the CYP reconstituted yogurt and YCMP mix reconstituted yogurt were analyzed daily for the first week and then weekly for a period of 8 wk. Sensory consumer testing of CYP reconstituted yogurt and YCMP mix reconstituted yogurt was conducted with 100 consumers. At 56 d, YCMP mix reconstituted yogurt had 5 log cfu/mL higher counts of Streptococcus thermophilus than the control (CYP reconstituted yogurt). Also, Lactobacillus bulgaricus counts of YCMP mix reconstituted yogurt were 6.55 log cfu/mL at 28 d and were 5.35 log cfu/mL at 56 d, whereas the CYP reconstituted yogurt from 28 d onwards had a count of <10 cfu/mL. The YCMP mix reconstituted yogurt also had significantly higher apparent viscosity and sensory scores for appearance, color, aroma, taste, thickness, overall liking, consumer acceptability, and purchase intent than CYP reconstituted yogurt. Overall, YCMP mix reconstituted yogurt had more desirable characteristics than CYP reconstituted yogurt. [ABSTRACT FROM AUTHOR]

The sweetener combinations played an important role in yoghurt making. In this study, we investigated the effects of rebaudioside A, erythritol, and isomalto-oligosaccharide (IMO) combinations on sensory score, hardness, consistency, viscosity, pH, and water-holding capacity of sugar-free yoghurt. A central composite rotatable design (CCRD) was adopted to obtain data for the correlative statistical models. Through the response surface analysis, the optimum formulation conditions of sweetener combinations were obtained by superimposing sensory properties, texture, pH, and water-holding capacity data, i.e. rebaudioside A 0.2 g/kg, erythritol 18.09 g/kg, and IMO 29.08 g/kg. In this condition, the quality of the yoghurt was acceptable, shown as harmonious taste, reasonable pH, exquisite texture, and high water-holding capacity. [ABSTRACT FROM PUBLISHER]

A national working group recently reached consensus that a guideline message for milk consumption should form part of the set of revised food-based dietary guidelines (FBDGs) for South Africa. The message was formulated as: “Have milk, maas or yoghurt every day”. This paper provides scientific support for this FBDG, based on the nutrition and health profile of South Africans; addresses concerns about possible detrimental effects of milk consumption, such as lactose intolerance, saturated fat and trans-fat content, milk allergies and dental caries in children; and identifies barriers to increased consumption. The guideline refers to milk, maas and yoghurt, and not all dairy products. This is based on the nutrient contribution of these products to a healthy diet. Milk (and some dairy products) has a low sodium-to-potassium ratio, as well as bioactive peptides, which may protect against the development of noncommunicable diseases. There is some evidence that the calcium in milk and dairy plays an important role in the regulation of body weight and bone mineral content in children. Available data show that milk and calcium intake in South Africans is low. Identified barriers include perceptions about lactose intolerance, taste, price, lack of knowledge on the nutritive value of milk and milk products, and possibly cultural taboos. As a result, increasing the consumption of milk, maas and yoghurt of South Africans will require active, multifaceted and multilevel promotion. [ABSTRACT FROM AUTHOR]

Liquid kashk is a fermented dairy product produced under two types of traditional liquid kashk and industrial liquid kashk in Iran. The basic raw material of both liquid kashks is yogurt. Dried Kashk-a traditional concentrated yogurt type dairy product- is used for traditional liquid kashk production. Industrial liquid kashk is produced by concentration of yogurt produced industrially. This research was designed to introuduce the production methods and to determine quality properties of liquid kashks. For this purpose, 30 traditional liquid kashks and 30 industrial liquid kashks were randomly collected from 10 provinces of Iran and their chemical, microbiologic and sensory properties were analysed. Results showed that the quality properties of both traditional liquid kashk and industrial liquid kashk samples were in compliance with the standards set by Institute of Standard and Industrial Researchs of Iran (ISIRI). [ABSTRACT FROM AUTHOR]

This study was conducted to determine effects of homogenization treatments under different pressures (150, 200 and 250 kg/cm2) on some physical, chemical, microbiological and sensory properties of ayran throughout the storage period of 1, 7 and 14 days. Whey separation of samples decreased while viscosity values increased with the increased homogenization pressure (P<0.05). It was identified that different homogenization pressures had no significant effects on chemical, microbiological and sensory properties of ayran samples (P>0.05). [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of increased vitamin D fortification (250 IU/serving) of high-temperature, short-time (HTST)-processed 2% fat milk, UHT-processed 2% fat chocolate milk, and low-fat strawberry yogurt on the sensory characteristics and stability of vitamin D during processing and storage. Three replicates of HTST pasteurized 2% fat milk, UHT pasteurized 2% fat chocolate milk, and low-fat strawberry yogurt were manufactured. Each of the 3 replicates for all products contained a control (no vitamin D fortification), a treatment group with 100 IU vitamin D/serving (current level of vitamin D fortification), and a treatment group with 250 IU vitamin D/serving. A cold-water dispersible vitamin D3 concentrate was used for all fortifications. The HTSTprocessed 2% fat milk was stored for 21 d, with vitamin D analysis done before processing and on d 0, 14, and 21. Sensory analysis was conducted on d 14. The UHTprocessed 2% fat chocolate milk was stored for 60 d, with vitamin D analysis done before processing and on d 0, 40, and 60. Sensory analysis was conducted on d 40. Low-fat strawberry yogurt was stored for 42 d, with vitamin D analysis done before processing, and on d 0, 28, and 42. Sensory analysis was conducted on d 28. Vitamin D levels in the fortified products were found to be similar to the target levels of fortification (100 and 250 IU vitamin D per serving) for all products, indicating no loss of vitamin D during processing. Vitamin D was also found to be stable over the shelf life of each product. Increasing the fortification of vitamin D from 100 to 250 IU/serving did not result in a change in the sensory characteristics of HTST-processed 2% fat milk, UHT-processed 2% fat chocolate milk, or low-fat strawberry yogurt. These results indicate that it is feasible to increase vitamin D fortification from 100 to 250 IU per serving in these products. [ABSTRACT FROM AUTHOR]

Aims: To analyse the effect of cell-associated peptidases in yogurt starter culture strains Lactobacillus delbrueckii ssp. bulgaricus (LB) and Streptococcus thermophilus (ST) on milk-protein-based antimicrobial and hypotensive peptides in order to determine their survival in yogurt-type dairy foods. Methods and Results: The 11mer antimicrobial and 12mer hypotensive milk-protein-derived peptides were incubated with mid-log cells of LB and ST, which are required for yogurt production. Incubations were performed at pH 4·5 and 7·0, and samples removed at various time points were analysed by reversed-phase high-performance liquid chromatography (RP-HPLC). The peptides remained mostly intact at pH 4·5 in the presence of ST strains and moderately digested by exposure to LB cells. Peptide loss occurred more rapidly and was more extensive after incubation at pH 7·0. Conclusions: The 11mer and 12mer bioactive peptides may be added at the end of the yogurt-making process when the pH level has dropped to 4·5, limiting the overall extent of proteolysis. Significance and Impact of the Study: The results show the feasibility of using milk-protein-based antimicrobial and hypotensive peptides as food supplements to improve the health-promoting qualities of liquid and semi-solid dairy foods prepared by the yogurt fermentation process. [ABSTRACT FROM AUTHOR]

In this study, cows' milk and aromatic cultures such as CH-1, YF-3331 and YC-350 used in production of yogurts. The volatile compounds in the samples were determined on the 1st, 7th, 14th and 21st days of storage by using static headspace gas chromatographic method. During storage, the amount of individual volatile compounds varied significantly in yogurts depending on type of culture used. The volatile compounds acetaldehyde, acetone, ethanol, acetoin, 2-furanmethanol and ethyl phthalate were determined in all samples. On day 1, acetaldehyde (82 mg/kg) was the highest compound in yogurt made using culture CH-1 which followed by yoghurts with YC-350 (66 mg/kg) and YF-3331 (54 mg/kg). Even though the amounts of acetaldehyde and ethanol decreased at the end of storage, acetoin increased in all the samples. While the amount of acetone in yogurt made using culture CH-1 showed fluctuations during storage, its levels in yogurts with cultures YF-3331 and YC-350 steadily increased and decreased, respectively. [ABSTRACT FROM AUTHOR]

The moisture sorption behaviour of curd (Indian yogurt) powder was studied at 20, 30, 40 and 50°C for water activity ranging from 0.07 to 0.85. GAB, BET, Henderson, Halsey, Chung & Pfost, Smith, Oswin and Peleg models were applied to analyse the data. Estimated parameters and fitting ability for sorption models were evaluated. The GAB model showed the best fit to the sorption data of curd powder at 20, 30 and 40°C, and the Peleg model fitted well at 50°C. [ABSTRACT FROM AUTHOR]

Texture perception and mouthfeel are sensory variables that still need further clarification. A reliable method to describe mouthfeel quantitatively by means of physicochemical measurements is missing so far. The current study focuses on a better understanding of the texture perception of yogurt. The final aim of the study consists of the development of a novel hybrid model, which is able to predict mouthfeel sensations objectively. For this purpose, cognitive methods are used in order to merge underlying data pools with respect to process parameters and the composition of dry matter content. These employed data pools result from rheological characterizations as well as sensory analyses of yogurt and from numerical simulations of fluid flow in a simplified anatomical model of the human mouth. This paper introduces the exact procedure of the study. Furthermore, the methods for generating the underlying data pools are described, and the results are presented. PRACTICAL APPLICATIONS The in-mouth model is based on fluid mechanics and enables the investigation of human consumption processes that accompany fluid flow in the oral cavity. Here, it reveals mechanical stimuli, which occur because of the movement of the tongue during deglutition. Therewith, the ongoing study affords a new approach to understand factors influencing the popularity and consumer acceptance of several products as their behavior in the mouth can be clarified. Having the software development completed, this innovation represents a great potential for the food industry. While supporting future sensory analyses, it both shortens development cycles of new products and optimizes existing foodstuff. [ABSTRACT FROM AUTHOR]

Texture properties of stirred low-fat yogurt were investigated in terms of processing after fermentation. The yogurt gel was pumped through a colloid mill at two gap widths and various peripheral velocities of the rotor. The storage modulus and yield stress were measured after 1 day and after 3 weeks, and the occurrence of syneresis was noted. The main factor for the structural degradation in the shear gap was the mean peripheral velocity of the rotor, rather than the apparent shear rate. Syneresis is related to a certain level of the storage modulus. The yield stress correlated with the storage modulus. [ABSTRACT FROM AUTHOR]

Picrotoxin is a neurotoxin found in the berries of Anamirta cocculus, a plant native to Southeast Asia. Picrotoxin has potential for being used as a biological weapon since the toxin is relatively easy to isolate and purify. Limited information exists on the stability and detection of picrotoxin added to foods before or after processing. The objective of this study was to determine the stability of picrotoxin during yogurt manufacture and storage. Direct, cup-set yogurt was produced by using methods that mimic the conditions used in full-scale production of yogurt. Milk (full-fat or low-fat) was pasteurized at 85 °C for 30 min, and then cooled to 43 °C. Yogurt starter culture (thermophilic culture or thermophilic + probiotic culture) and picrotoxin (200 μg/mL milk) were added. Samples of yogurt during fermentation (5 to 6 h, 43 °C) and during 30 d refrigerated (4 to 6 °C) storage were analyzed for pH, titratable acidity, and picrototoxin levels. Regardless of starter culture used or fat content of milk, there were no significant differences in the pH and titratable acidities of the picrotoxin-spiked yogurt and the control yogurt (no added picrotoxin) during fermentation and up to 4 wk of refrigerated storage. The color or texture of the yogurt was not affected by addition of picrotoxin. Levels of picrotoxinin and picrotin (components of picrotoxin) in yogurt, as measured by LC/MS (APCI+/SIR) did not change significantly during fermentation and storage. A separate experiment determined that addition of picrotoxin to milk before pasteurization (85 °C, 30 min) did not affect picrotoxin stability. These results indicate that picrotoxin is stable in yogurt during manufacture and storage. [ABSTRACT FROM AUTHOR]

Bulgarian yogurts were manufactured and fortified with 8, 15 and 27 mg of iron kg−1 of yogurt. The growth and acidifying activity of the starter culture bacteria Streptococcus thermophilus 13a and Lactobacillus delbrueckii subsp. bulgaricus 2-11 were monitored during milk fermentation and over 15 days of yogurt storage at 4 °C. Fortifying milk with iron did not affect significantly the growth of the starter culture during manufacture and storage of yogurt. Counts of yogurt bacteria at the end of fermentation of iron-fortified milks were between 2.1 × 1010 and 4.6 × 1010 CFU ml−1, which were not significantly different from numbers in unfortified yogurts. In all batches of yogurt, the viable cell counts of S. thermophilus 13a were approximately three times higher than those of L. delbrueckii subsp. bulgaricus 2-11. Greater decrease in viable cell count over 15 days of storage was observed for S. thermophilus 13a compared to L. delbrueckii subsp. bulgaricus 2-11. Intensive accumulation of lactic acid was observed during incubation of milk and all batches reached pH 4.5 ± 0.1 after 3.0 h. At the end of fermentation process, lactic acid concentrations in iron-fortified yogurts were between 6.9 ± 0.4 and 7.3 ± 0.5 g l−1. The acidifying activity of starter culture bacteria in the control and iron-fortified milks was similar. There was no increase in oxidized, metallic and bitter off-flavors in iron-fortified yogurts compared to the control. Iron-fortified yogurts did not differ significantly in their sensorial, chemical and microbiological characteristics with unfortified yogurt, suggesting that yogurt is a suitable vehicle for iron fortification and that the ferrous lactate is an appropriate iron source for yogurt fortification. [ABSTRACT FROM AUTHOR]

Abstract: The influence of packaging polymers (polypropylene or polystyrene) on the sensory and physicochemical characteristics of flavoured stirred yogurts with either 0% or 4%-fat content was investigated during the 28 days of storage at 4°C. Regardless of the packaging type, complex viscosity and thickness perception increased during storage due to exopolysaccharide production, whereas the pH of yogurts decreased. Packaging type had a greater impact on 0%-fat yogurts than on 4%-fat yogurts for both sensory and physicochemical characteristics. During storage, 0%-fat yogurt conditioned in glass displayed the lowest aroma quantity decrease of the three types of packaging, in accordance with the olfactory properties. However, between the two polymer types, polystyrene packaging seemed to be preferable for limiting aroma compound losses and subsequent fruity note intensities, and for avoiding the development of odour and aroma defects. Less significant packaging effect was observed for 4%-fat yogurts. [Copyright &y& Elsevier]

Abstract: The effect of commercial fruit preparations (mango, mixed berry, passion fruit and strawberry) on the viability of probiotic bacteria, Lactobacillus acidophilus LAFTI® L10 and Bifidobacterium animalis ssp. lactis LAFTI® B94 in stirred yogurts during storage (35 days) at refrigerated temperature (4°C) was evaluated. The results showed that addition of either 5 or 10g/100g fruit preparations had no significant (p>0.05) effect on the viability of the two probiotic strains except on L. acidophilus LAFTI L10 yogurt with 10g/100g passion fruit or mixed berry. After the addition of fruit preparation, 96% of the yogurts incorporated with fruit preparation did not exhibit a greater loss in the viability of probiotic bacteria compared to plain yogurt during the storage period. A correlation between the post-storage pH in yogurts and the survival of probiotic bacteria was observed. All the yogurts, however, contained the recommended levels of (106–107 cfu/g) probiotic bacteria at the end of 35-day shelf life. [Copyright &y& Elsevier]

Abstract: Jicama and maize starches were hydrolyzed with HCl (1.5, 3.0 or 4.5g/100g of starch), at a temperature of 40°C using two hydrolysis times (3 and 6h). The acid degradation of both starches was not excessive as revealed by the positive blue value, amylose content, gel formation and gel thermo-reversibility. Jicama starches were more susceptible to acid hydrolysis than maize starches. Hydrolyzed jicama starches showed low values of gel strength and water solubility index, and high values of damaged starch, total sugar content and water absorption index. Stirred yogurt formulated with hydrolyzed starches showed different properties of syneresis index according to the starch type and hydrolysis conditions. Yogurt samples with hydrolyzed jicama starches added did not show significant differences in pH and viscosity. Sensorial testing showed that it is possible to produce yogurt with good functional and sensorial properties using hydrolyzed jicama starches as a fat substitute. [Copyright &y& Elsevier]

Abstract: There has been great demand of calcium fortified dairy products as they can serve as an ideal vehicle for carrying extra calcium to fulfill the nutritional needs but there is need to generate information on the effect of fortification of calcium on the physical properties of these products. In the present study, the calcium enriched mango yogurt was prepared after fortification of pasteurized yogurt mix with 50mgCa/100ml of calcium lactate, this level selected from a preliminary study of sensory evaluation. Fortification of yogurt with calcium lactate at this level significantly (P<0.005) increased the water holding capacity (WHC) by 2.99% on 1st day of storage. WHC of calcium fortified fruit yogurt was higher than control fruit yogurt on 7th and 14th day of storage. Measurements performed on slowly stirred samples (flow curves and final apparent viscosity) showed that calcium-enriched fruit yogurt had stronger structures. Calcium fortified fruit yogurt showed less shear thinning behavior as compared to control. Also, apparent viscosity measurements at constant shear rate showed a significantly (P<0.05) less decrease in initial apparent viscosity in calcium fortified fruit yogurt. However, no statistically significant (P>0.05) difference was observed in tan δ values of control and calcium fortified fruit yogurt indicating similar nature of bonds involved in the gel structure formation of both the yogurt samples. The more firm structure of the calcium fortified fruit yogurt is thus attributed to the higher extent of colloidal calcium phosphate cross-linking between casein micelles due to increased calcium content by fortification. Also flavor, color, and body and texture scores of control and calcium fortified fruit yogurt did not show any significant difference (P>0.05). [Copyright &y& Elsevier]

The simultaneous effects of fermentation temperature (20.8–29.2C), total solids (TS) level (13–16% w/v) and total inoculum level (1–4% v/v) on the acidification process in buffalo milk fermented with dahi culture were explored by means of response surface methodology. The changes in lactose content and lactic acid in buffalo milk (14.5% TS) inoculated with 2.5% culture were investigated during fermentation at 27.5C. The utilization of lactose followed first order kinetics during dahi fermentation. The syneresis increased with increase in fermentation temperatures. A firmer gel was achieved with a medium acidification rate in the range of fermentation temperatures from 27C to 29.2C, medium TS of 14.5–15%, and at a total inoculum level of 2.5%. [ABSTRACT FROM AUTHOR]

Abstract: The effect of manufacturing yogurt with a wide variation in Lactobacillus acidophilus inoculation level while holding the yogurt culture inoculation level constant on the properties of the resulting yogurt was determined to find out if any problems can occur if an excessively high level of L. acidophilus is used in yogurt production. Four batches of plain, set-style yogurt were manufactured with skim milk, nonfat dry milk, yogurt cultures, and with or without L. acidophilus (0, 0.0239, 0.238, or 2.33g/100g). After homogenization, pasteurization, and cooling, yogurt mixes were inoculated, poured into containers, incubated to pH 4.5, and cooled. Lactobacilli and L. acidophilus counts, pH, amount of syneresis, color, apparent viscosities, and sensory scores were determined during storage. The yogurt inoculated with 0.238g/100g L. acidophilus had the highest L. acidophilus counts from 4 to 7wk. Yogurts inoculated with 2.33g/100g L. acidophilus generally had lower lactobacilli counts, L* values, apparent viscosities, and sensory scores but more syneresis and higher a* and b* values than the remaining yogurts. An excessively high inoculated level of L. acidophilus (2.33g/100g) resulted in an inferior quality yogurt. [Copyright &y& Elsevier]

The aim of this work was to evaluate the suitability of yogurt containing açaí pulp as a food carrier of probiotic cultures. Probiotic yogurts containing increasing amounts of açaí pulp (3, 5 and 7%) were processed and submitted to a physicochemical analysis and viable microbial count during refrigerated storage. In general, all the physicochemical parameters showed variations proportional to the amount of açaí pulp in the product formulation. Probiotic activity was verified throughout refrigerated storage for all the products, although there was a fall of one logarithmic cycle for both micro-organisms during this period (107–108 CFU/mL). [ABSTRACT FROM AUTHOR]

Abstract: The objective was to study the effect of heart healthy nutrients on the physico-chemical, microbiological and sensory characteristics of yogurt. Thiamine (vitamin B1), riboflavin (vitamin B2), niacin (vitamin B3), folic acid (vitamin B9), manganese and magnesium were added during mix preparation at 0%, 30%, 60% and 90% of their respective recommended dietary allowance (RDA). Fiber (Ceolus Fiber DF-17) was added at a constant rate of 176g/7.570kg yogurt mix in all the treatments. Total solids in the control were kept constant with non-fat dry milk. Incorporation of the heart healthy nutrients at the 30%, 60% and 90% RDA significantly decreased syneresis, pH, L*, a* values but significantly increased b* value. Product viscosity was significantly increased by the incorporation of the nutrients at 60% of their respective RDA''s. The incorporation of the above heart healthy vitamins and minerals at any of the studied rates in yogurts did not significantly affect flavor, appearance, body and texture and microbial counts of the product. Although there were subtle yet significant changes in instrumental color and viscosity these slight changes could not be detected by sensory evaluation. Yogurts can successfully be manufactured with the above heart healthy nutrients. [Copyright &y& Elsevier]

Abstract: Stirred yogurts with the same chemical composition but prepared using different procedures had different gel particle diameters and different rheological characteristics. Sensorial evaluations were performed and compared with instrumental analyses. The smoothness perceived both visually and orally varied with the size of the particles of the stirred gels. For products with small particle sizes, the consistency was related to viscoelastic parameters. It was shown that products perceived as creamy were firm. When particle size was above 150μm, it seemed impossible to perceive creaminess. Nevertheless, results obtained from two commercial products containing fat and starter showed that creaminess perception could not be reduced to simple relationships between gel firmness and particle size in the case of stirred gels. [Copyright &y& Elsevier]

The aim of this study was to produce yogurt from Iranian autochthonous starters. Strains of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus were isolated from autochthonous yogurts. The strains were used as starter for yogurt production. Chemical, microbial and organoleptic characteristics of products were examined. There were significant increases in acidity and acetaldehyde content, and significant decreases in pH and microbial population of samples during cold storage. There was no significant difference in organoleptic characteristics (taste, smell and texture) during cold storage. We conclude that autochthonous starters in production of yogurt can be satisfactorily used and the starters can introduce to national microbial collection. [ABSTRACT FROM AUTHOR]

The effect of the addition of gelatin and starch on the rheological and sensory texture properties of sweetened plain stirred yogurt was studied. Six samples were prepared: two with gelatin (3 and 6 mg/g), three with starch (1, 5 and 10 mg/g) and a control sample without thickener. Rheological measurements were performed and flow curves were modelled according to the Herschel–Bulkley rheological model. Also, sensory evaluation was carried out using a trained panel. The addition of gelatin and starch significantly affected the instrumental texture parameters (Herschel–Bulkley's model parameters and syneresis) and the perceived sensory texture of yogurts. All sensory descriptors were well predicted by the partial least squares regression of the instrumental parameters. The addition of thickeners significantly reduced syneresis. Samples produced with 6 mg/g of gelatin did not show syneresis and showed the highest sensory viscosity, creaminess and mouth-feel. Therefore, the use of 6 mg/g of gelatin could be a reasonable concentration to use in the production of low-fat yogurts. [ABSTRACT FROM AUTHOR]

In this work, response surface methodology was applied to a study of the effects of the addition of skim milk powder and stabilizers on the apparent viscosity and sensory attributes of nonfat yogurt. The addition of stabilizers has been shown to produce a significant effect on sensory attributes, while high concentrations of xanthan and guar gum are seen to decrease the overall acceptability of the yogurt, with gelatin producing the higher apparent viscosity and consistency. The correlation among apparent viscosity, which is an instrumental measurement, and consistency, which is a sensory evaluation, was 0.72. [ABSTRACT FROM AUTHOR]

Abstract: The relative contributions of sensory properties, fat content, price, method of processing, and presumed absence of preservatives in the product to purchase intents of concentrated yogurt (Labneh) were evaluated by conjoint analysis. Three hundred subjects tasted Labneh samples identified by different combinations of attribute levels and rated their intents to purchase the products. Analysis of the subjects’ responses revealed preference for higher levels of fat in the product and that purchase intents are largely dominated by sensory properties and fat contents. Fat levels and sensory properties accounted for 65.46% while price, method of processing, and presumed absence of preservatives in the product contributed for 34.54% of purchase intents. Cluster analysis identified four segments of consumers with similar preferences for sensory properties and fat levels and response to presumed absence of preservatives in products. Apart from the product purchased/consumed by respondents, behavioral and demographic characteristics of subjects were not related to segment membership. Information on fat levels and other extrinsic attributes of the product have secondary effects on purchase decisions of concentrated yogurt when evaluated by conjoint analysis models incorporating actual tasting of products in the study design. Actual tasting of products masked possible effects of behavioral and demographic characteristics of respondents on purchase intents of Labneh. [Copyright &y& Elsevier]

Abstract: The aim of the present study is to contribute to a correct determination of vegetal sterol and stanols found in enriched milks and yogurts, used as functional foods, using GC–MS. The optimization of the method, specially the saponification step, as well as the corresponding analytical validation, is the main goal of this study. Saponification temperatures and times that gave the best results were 80°C/45min for milk, and 60°C/90min for yoghurt samples. KOH concentration solutions of 2.0 and 2.5M were selected as the best saponification reagents for milk and yoghurt, respectively. It was also verified that volumes of 1500μl and 2500μl KOH were enough to react with 250μl of milk and 100μl of yoghurt. Accuracy, repeatability and intermediate precision of the method were calculated at 89.2% and 91.5%, 6.0% and 4.45%, 11.8% and 9.4%, for milk and yoghurt, respectively, while the limit of detection was determinate at 0.1μg/ml for both matrices. [Copyright &y& Elsevier]

Abstract: This study investigated the physical, chemical and sensory characteristics of non-fat yogurts treated with microbial transglutaminase (MTGase) at varying concentrations from 0 to 0.5gL−1. Also, the effect of enzyme inactivation prior to fermentation on the selected properties of the yogurts was studied. Acid development rate was reduced with increasing MTGase doses. Cross-linking of milk proteins by MTGase had a growth-slowing effect on yogurt starter bacteria, which was more pronounced at higher concentrations. Physical properties of the yogurts were improved by MTGase throughout 21-day storage; on the contrary, the production of acetaldehyde was slowed down by increasing MTGase concentrations during the same period. Principal component analysis (PCA) and hierarchial cluster analysis (HCA) clearly differentiated the samples with added MTGase at lower (⩽0.3gL−1) and higher (0.4–0.5gL−1) concentrations regarding the physical and sensory properties. The physical and sensory properties of non-fat set yogurt could be improved by incorporating MTGase up to a level of 0.3gL−1. [Copyright &y& Elsevier]

A generic methodology for the assessment of consumer exposure to substances migrating from packaging materials into foodstuffs during storage is presented. Consumer exposure at the level of individual households is derived from the probabilistic modeling of the contamination of all packed food product units (e.g. yogurt pot, milk bottle, etc.) consumed by a given household over 1 year. Exposure of a given population is estimated by gathering the exposure distributions of individual households to suitable weights (conveniently, household sizes). Calculations are made by combining (i) an efficient resolution of migration models and (ii) a methodology utilizing different sources of uncertainty and variability. The full procedure was applied to the assessment of consumer exposure to styrene from yogurt pots based on yearly purchase data of more than 5400 households in France (about 2 million yogurt pots) and an initial concentration c0 of styrene in yogurt pot walls, which is assumed to be normally distributed with an average value of 500 mg kg-1 and a standard deviation of 150 mg kg-1. Results are discussed regarding both sensitivity of the migration model to boundary conditions and household practices. By assuming a partition coefficient of 1 and a Biot number of 100, the estimated median household exposure to styrene ranged between 1 and 35 µg day-1 person-1 (5th and 95th percentiles) with a likely value of 12 µg day-1 person-1 (50th percentile). It was found that exposure does not vary independently with the average consumption rate and contact times. Thus, falsely assuming a uniform contact time equal to the sell-by-date for all yogurts overestimates significantly the daily exposure (5th and 95th percentiles of 2 and 110 µg day-1 person-1, respectively) since high consumers showed quicker turnover of stock. [ABSTRACT FROM AUTHOR]

The development of starters employed in the yogurt elaboration was evaluated with 300 mg/kg of potassium sorbate. Five experiments with 40 kg of natural yogurt were made. This preservant (0,03 %) was added to the half of product and the rest stayed as control. Both variants were analyzed by means of acidification curve, pH and morphological observations. The physico-chemical and microbiological indexes were determined at 24 h. The shelf-life was also evaluated. The experimental variant showed acidity and pH indexes lower than control. Furthermore, morphological deformations of the starters in the incubation and conservation stages were observed. The variant with preservant showed viability less than 107 ufc/g during the 5 first days, due to its shelf-life resulted annulled at 24 h. However, the control arrived to the end of conservation stage at 15 days. [ABSTRACT FROM AUTHOR]

Abstract: The objectives of this study were to investigate the effects of enzymatic cross-linking of milk proteins on the functional properties and probiotic culture survivability of goat milk yogurt. After pre-incubation (50°C, 1h) of the milk with microbial transglutaminase [MTGase, 0–4 units (U)/g protein] and subsequent heat inactivation (75°C, 5min), yogurt was prepared by inoculating the milk with a commercial probiotic yogurt starter containing probiotic cultures (Lactobacillus acidophilus, Bifidobacteria, and Lactobacillus subsp. casei) and incubating the inoculated milk at 43°C for 5h. Compared to the untreated control trial, pretreatment of the milk with MTGase (2 and 4U/g protein) increased (P <0.05) the viscosity and decreased the syneresis of yogurt samples. The effect of enzyme treatment was more significant in improving the viscosity of yogurt compared to the method of increasing total solids (TS) in the milk. No significant differences in basic nutrient contents between control and enzyme-treated samples were observed. The probiotic cultures were relatively stable in the goat milk yogurt and their populations remained above 106 CFU/g during the 8-week storage period at 4°C. No significant differences in rate of change of population of all the three probiotic cultures were observed between the control and the MTGase treated groups. Microbiological analysis shows that the enzymatic cross-linking of proteins seems to have a positive role in the survivability of the probiotic cultures, which requires further investigation. Scanning electron microscopic studies revealed that the microstructure of the enzyme-treated samples appeared denser than the control, suggesting that pretreatment of milk by MTGase could be used to improve the microstructure of the yogurt gel. Results of this study indicate that enzymatic cross-linking of milk proteins by MTGase appears to be an effective means for improving the functional properties of goat milk yogurt. MTGase treatment may be a useful method in the production of probiotic goat milk yogurt products. [Copyright &y& Elsevier]

Abstract: A new approach for the rapid and lossless discrimination of varieties of yogurt by Visible/NIR-spectroscopy was put forward. Through the principal component analysis of spectroscopy curves of 5 typical kinds of yogurt, the clustering of yogurt varieties was processed. The results end to be that the cumulate reliabilities of the first two principle components (PC1, PC2) were more than 98.9%, and the first seven principle component (PC1 to PC7) were 99.97%. In addition, an artificial neural network (BP-ANN) model was set up. The first seven principles components of the samples were applied as BP-ANN inputs and the values of the type of yogurt were applied as outputs, which build the three-layer BP-ANN. With this model, the discrimination of yogurt came to be possible. The results of distinguishing the rate of the five yogurt varieties came to be satisfied. It presented that this model was reliable and practicable. [Copyright &y& Elsevier]

Whether Lactobacillus delbrueckii subsp, bulgaricus and Streptococcus thermophilus can be recovered after passage through the human gut was tested by feeding 20 healthy volunteers commercial yogurt. Yogurt bacteria were found in human feces, suggesting that they can survive transit in the gastrointestinal tract. [ABSTRACT FROM AUTHOR]

Yogurts made with 80% milk retentate (MR) [Volume Reduction Factor (VRF) = 1.5] and 20% cheese whey retentate (WR; VRF = 8.0) (yogurt 1) and yogurts made with 100% MR through ultrafiltration have been evaluated as to flow, texture profile analysis (TPA) and syneresis index. As with MR and WR, their physico-chemical composition was also determined. The yogurt to which WR had been added showed; less apparent viscosity and greater tixotrophya; less firmness and adhesiveness and greater cohesiveness; higher syneresis index, less protein and mineral content, and greater lipid content in comparison with the yogurt made only with MR. [ABSTRACT FROM AUTHOR]

Abstract: Data from sensory shelf-life studies can be analyzed using survival statistical methods. The objective of this research was to introduce Bayesian methodology to sensory shelf-life studies and discuss its advantages in relation to classical (frequentist) methods. A specific algorithm which incorporates the interval censored data from shelf-life studies is presented. Calculations were applied to whole-fat and fat-free yogurt, each tasted by 80 consumers who answered “yes” or “no” to whether they would consume samples with different storage times. The Bayesian approach was used to obtain the failure functions and the estimated shelf lives of the yogurts. Two approaches were considered: first non-informative priors were used, and then results from the fat-free yogurt were used to construct a more informative prior for the whole-fat product. For both approaches a Weibull distribution was assumed. For the non-informative priors the results were analogous to those obtained by the classical methods. When an informative prior was used to estimate the whole-fat shelf-life parameters, there was a tendency to closer credible limits in the percentile distributions. Advantages of the Bayesian approach are discussed: no need for asymptotical assumptions and the possibility of improving the precision of the results by introducing external information. [Copyright &y& Elsevier]

Recently, increased demand for low-calorie products and foods with alternative sweeteners has gained special attention. Intense sweeteners avoid the problems of health risks associated with caloric sweeteners. This paper presents information about the technical characteristics of the more widely used artificial sweeteners and the possibility of their application in low-calorie yogurts. [ABSTRACT FROM AUTHOR]

Yogurt and bio-yogurt were manufactured from ewe's milk using a starter culture and a probiotic culture. Incubation was carried out at 37°C and 42°C until pH 4.6 was reached and the yogurts were stored at 4 +1°C for 14 days. Analysis after 1, 7 and 14 days showed that incubation temperature and storage time significantly influenced overall properties of the samples. During the storage, whey separation and pH decreased, but titratable acidity, lactic acid and volatile fatty acid contents increased. Viable bacterial counts in all bio-yogurts were above 107 cfu g−1 at the end of storage. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the influence of sensory and texture properties of natural yoghurts on their overall sensory quality and acceptability. Samples were evaluated by consumers, and a parallel quantitative descriptive analysis (QDA) was carried out, including analysis of thickness and smoothness. Results were analysed by principal component analysis (PCA). Measurements of yoghurt viscosity were carried out using Brookfield instruments. Sensory texture properties (thickness and smoothness) were not significantly correlated with yoghurt consumer acceptability. Viscosity measured instrumentally correlated well with sensory thickness. Negative sensory attributes (especially off-flavour and bitterness) were of critical importance for consumer acceptance. [ABSTRACT FROM AUTHOR]

Yogurt and bio-yogurt were made using a starter culture and a probiotic culture. Incubation was carried out at 37°C and 42°C until pH 4.6 was reached and the yogurts were stored at 4+1°C for 14 days. Yogurts were analysed 1, 7 and 14 days after production. In the samples the levels of acetaldehyde, lactic acid, titratable acidity and whey separation were determined. Viable bacterial counts and sensory assessment were also determined. The incubation temperature and storage time significantly influenced overall properties of the samples. During storage, whey separation, pH and acetaldehyde decreased, but titratable acidity and lactic acid increased. Viable bacterial counts in all bio-yogurts were above 107 cfu g-1 at the end of storage. Whey separation, titratable acidity and lactic acid contents were lower, while acetaldehyde and viable bacterial counts were higher in the bio-yogurts incubated at 37°C in comparison to bio-yogurt incubated at 42°C. This indicates that lower temperature incubation can be used satisfactorily for the manufacture of bio-yogurt. [ABSTRACT FROM AUTHOR]

The effect of Lactobacillus reuteri against one of the major cariogenic organism, Streptococcus mutans, was studied. Yogurt products containing L.reuteri showed a significant growth inhibitory effect against S. mutans, whilst yoghurts with lactobaccilli other than L. reuteri did not show such inhibition. Further, double-blind, placebo-controlled trial demonstrated that consuming yogurt with L. reuteri significantly reduced the oral carriage of mutans streptococci, compared with the placebo yogurt. [Copyright &y& Elsevier]

Flash profile is a quick sensory profiling technique designed to meet industrial needs. It is based on the combination of free choice profiling and a comparative evaluation of the whole product set. This study aimed at comparing Flash profile with conventional profiling. This has been done with two product spaces: strawberry blended yoghurts and apricot “fromages frais”, both from the French market. Multidimensional data treatment such as Generalised Procrustes Analysis and Canonical Variate Analysis (CVA) allowed us to assess the correspondence between the sensory maps obtained with both methods. In the case of strawberry yoghurts, very similar results were obtained with the two methods. On the other hand the sensory positioning of the apricot fresh cheeses somewhat differed between the methods. For both product sets, Flash profile was slightly more discriminating than the conventional profile. Advantages and limits of Flash profile are discussed. [Copyright &y& Elsevier]

In this study the survival of Escherichia coli O157:H7 in the production process of acidophilus yogurt was examined and compared with traditional yogurt. Milk was inoculated with different doses of E. coli O157:H7 (102, 104 and 106 CFU mL-1) and two kinds of yogurt were produced. Samples were taken for pH measurements and bacterial enumeration at 0, 3, 24, 48, and 72 h after inoculation. Escherichia coli O157:H7 was analysed by using a Most Probable Number technique and yogurt starter culture and Lactobacillus acidophilus were counted by using classical culture methods. Elimination times of E. coli O157:H7 were determined for 102 CFU mL-1 as 3 h, and for 104 and 106 CFU mL-1 as 48 h in acidophilus yogurt. Elimination times in traditional yogurt were 48 h for 102 and 104 CFU mL-1 and 72 h for 106 CFU mL-1 E. coli O157:H7. In conclusion, the elimination time of E. coli O157:H7 in acidophilus yogurt was shorter than in traditional yogurt during the processing and post-processing stages. [ABSTRACT FROM AUTHOR]

Rheological, physico-chemical and organoleptic studies were made on five types of yoghurt originally from pure caprine milks of an Alpine breed and local breeds, pure ovine milk of the Lacaune breed, and two mixtures containing 50% caprine milk from an Alpine breed + 50% ovine milk of the Lacaune breed and 70% caprine milk of local breeds + 30% ovine milk of the Lacaune breed. Comparison of the yoghurts showed that it was possible to produce yoghurt of good quality from the last four types of milk. In contrast, pure caprine milk from an Alpine breed was not suitable for the production of yoghurt as this milk is low in dry matter and the yoghurt that was produced had the lowest firmness and significantly inferior organoleptic characteristics. Yoghurts prepared from mixtures of 50% caprine milk of an Alpine breed + 50% ovine milk of the Lacaune breed, and 70% caprine milk of local breeds + 30% ovine milk of the Lacaune breed, were of good quality, with similar consistency, rheological and organoleptic characteristics. [ABSTRACT FROM AUTHOR]

Yogurt is a milk curd produced all over the world, obtained by a lactic fermentation of a milk base enriched with milk proteins, and sometimes sugars and thickeners. One of the most important sensorial attributes for yogurt is texture, which could be assessed by sensory or instrumental analysis. A lot of work has been published in studying the contribution of milk base, starter, and process on yogurt texture in order to develop new textures, or simply to reduce fat content, or the level of addition of protein and thickener in milk. However, these studies are limited to only a few factors. The topic of this review was to synthesize the data of literature, with the aim of extracting and classifying factors on the basis of their influence on yogurt texture. Three factors, milk base heating, starter, and yogurt shearing after fermentation, respectively, play a key role in the elaboration of texture. The control of these three parameters allows the improvement of the textural attributes of yogurts by 2 to 15 times. [ABSTRACT FROM AUTHOR]