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The use of skim milk is a strategy to increase goat milk yogurt acceptability. However, it can negatively affect yogurt rheology because fat plays a vital role in dairy structural integrity. Thus, this study aimed to investigate the effects of fat replacers on the rheological, physical, and sensory parameters of low-fat cupuassu goat milk yogurts during refrigerated storage (28 days). Five goat milk yogurts formulations were carried out: whole yogurt (WY), skim yogurt (SY), skim yogurt with inulin (SIY), skim yogurt with maltodextrin (SMY), and skim yogurt with whey protein (SWY). Treatments were subjected to bacterial counts, chemical composition, pH, water holding capacity, instrumental color and texture, rheological and sensory analyses. All samples showed reducing pH values, water holding capacity, and L* and b* value during storage. Regarding texture, the firmness and consistency decreased during storage. On the other hand, the viscosity index significantly increased during refrigerated storage time. Moreover, all treatments exhibited viscoelastic behaviour. In addition, SIY and SMY showed the highest apparent viscosity. Furthermore, SIY, SMY, and SWY formulations exhibited positive sensory scores for appearance, color, aroma, texture, and viscosity. However, the overall acceptability and purchase intention did not differ statistically between WY and the fat-replacement treatments (SIY, SMY, and SWY). These results indicate that fat substitutes improved the quality of skimmed formulations. Thus, inulin and maltodextrin have the potential as functional fat replaces to produce low-fat goat milk yogurts.

A new procedure for the determination of biogenic amines (BAs), putrescine, cadaverine, spermidine, spermine and tyramine, based on the purification through precipitation and centrifugation of peptides in an acid extract from the sample is proposed. The novelty of the procedure in relation to the liquid-liquid purification reported in the literature is based on shortening the time of analysis and reducing BAs losses during sample preparation. The procedure permitted better precision, recovery, and sensibility, particularly in lower concentration levels, when compared to extraction without purification before derivatization. The method was applied to the simultaneous determination of the five aforementioned BAs in commercial yogurt samples by reversed-phase high-performance liquid chromatography (RP-HPLC). The procedure presented adjusted correlation coefficients between 0.980 and 0.997, and linear range in samples of 1–50 mg L−1 (cadaverine), 3–50 mg L−1 (putrescine, spermidine and spermine) and 5–50 mg L−1 (tyramine), with accuracy ranging from 67.81% to 142.78% in the limit of quantification (LOQ) and from 88.99% to 118.26% in other concentration levels. The limit of detection of BAs in yogurt samples was 0.18–4.01 mg L−1, while LOQ ranged between 1 and 5 mg L−1. The intraday relative standard deviation was ≤15.74% in LOQ and ≤10.05% in other concentration levels. The purification step by precipitation was fundamental to eliminate the interferences present in the yogurt samples, and it was relevant to increase the sensitivity of BAs detection when compared to liquid-liquid purification. Keywords: Extract purification, Sample preparation, In-house validation method, Tyramine, Cadaverine, Putrescine, Fermented milk, FDA Guidelines, Decision limits, Detection capabilities

An analytical method was developed and validated for the determination of maltodextrin in raw milk, using high-performance liquid chromatography with evaporative light scattering detection. Maltodextrin content was evaluated in adulterated raw milk using a Supelcosil LC-NH2 (25cm×4.6mm) column and isocratic elution (68% of acetonitrile). Validation parameters exhibited adequate linearity, with relative standard deviation values between 0.74 and 2.16% (n=10) for repeatability and 0.11-19.39% (n=5) for intermediate precision. Limits of detection and quantification were 0.78 and 1.56mg.mL(-1), respectively, and recovery rates were between 91 and 93% for three levels. The application of this method shows that maltodextrin concentrations found in adulterated samples are lower than expected, which may be related to the quality of the commercial maltodextrin used. The method proposed proved to be simple and appropriate for the determination of maltodextrin in raw milk, with detection down to adulteration levels of 1%.

The purification of caprine milk oligosaccharides (COS) by membrane filtration has been hampered by the low concentration of target COS and high concentration of lactose. In addition, their molecular weight proximity hinders the recovery of a COS fraction with high degree of purity and recovery yield. In this work, the recovery of a high purity COS concentrate was obtained by the optimization of an integrated approach including complete lactose hydrolysis, fermentation of the resulting monosaccharides and nanofiltration. All carbohydrates were quantified using High Performance Anion Exchange Chromatography with Pulsed Amperometric Detection (HPAEC PAD). Defatted goat whey was ultrafiltered with discontinuous diafiltrations to increase the recovery of COS in the whey permeate which was then subsequently concentrated by nanofiltration. COS recovery yields of 75% with negligible amounts of monosaccharides (0.3% of the initial amount of lactose in the whey permeate) were achieved. A final retentate containing 67.6 and 34.4% of acidic and neutral oligosaccharides respectively was obtained from caprine milk.

CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior FAPERJ - Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro Bioactive amines (BAs) represent a considerable toxicological risk in fermented dairy products because they provide the ideal environment for their formation. Thus, secondary control measures to prevent or reduce BAs formation in dairy products are urgently needed. However, additional scientific knowledge about the factors affecting BAs production and the interaction among them is currently necessary to achieve this goal. In this context, Partial Least Square with Variable Importance in Projection (PLS-VIP) analysis followed by cross-validation was applied to variables to investigate their interactive effect on BAs accumulation in cow's and goat's fermented milk during refrigerated storage. Streptococcus thermophilus and Lactobacillus acidophilus LA-5 increased tyramine and total BAs content in both cow's (CFM) and goat's (GFM) fermented milks. In CFM, Maillard reaction involving galactose and increased post acidification interacted to enhance accumulation of BAs (R2 = 0.895, P = 1.11 × 10−5); whereas for GFM, losses of consistency coefficient and viscosity were essential for BAs accumulation (R2 = 0.919; P = 2.72 × 10−6). These findings show that by preventing Maillard reaction and delaying post acidification in CFM, as well as by controlling viscosity in GFM, there can be mitigation of BAs formation during storage.

Although the demand for goat milk products has been growing, they have lower consumer acceptability than products derived from cow milk. However, the addition of cupuassu pulp can be used to improve the formulation of these products. For this reason, the aim of this study was to investigate the influence of new goat milk yogurt manufactured with cupuassu pulp on physicochemical properties, consumers' perceptions, and overall consumer acceptance. In addition, the effect of antioxidant health information on consumer acceptance and purchase intention of cupuassu goat milk yogurts was evaluated. The results demonstrated a positive expectation regarding linking and familiarity to goat milk products and products with cupuassu pulp. The pH, total phenolic content, lightness, redness, yellowness, and apparent viscosity were potentially affected by the addition of cupuassu, with the highest concentration of cupuassu (10%) exhibiting the greatest changes in parameters. Based on principal component analysis, partial least squares regression, and just-about-right and penalty analysis, the addition of cupuassu pulp improved some sensory attributes of goat milk yogurt, such as cupuassu aroma, cupuassu flavor, yellow color, consistency, and viscosity, which positively influenced product acceptance. In addition, antioxidant health information increased the acceptance and purchase intention of cupuassu goat milk yogurts. Taking into account the parameters investigated in this study, the best scoring formulation was goat milk yogurt with 10% cupuassu pulp. Our results suggest that cupuassu pulp can be considered a potential ingredient to improve the sensory and texture properties of goat milk yogurt. Furthermore, the antioxidant health information could be a sensory strategy to increase the acceptance of cupuassu goat milk yogurts.

Scope The microorganisms that make up kefir grains are well known for lactose fermentation, but the extent to which they hydrolyze and consume milk proteins remains poorly understood. Peptidomics technologies were used to examine the proteolytic activity of kefir grains on bovine milk proteins. Methods and results Gel electrophoresis revealed substantial digestion of milk proteins by kefir grains, with mass spectrometric analysis showing the release of 609 protein fragments and alteration of the abundance of >1500 peptides that derived from 27 milk proteins. Kefir contained 25 peptides identified from the literature as having biological activity, including those with antihypertensive, antimicrobial, immunomodulatory, opioid and anti-oxidative functions. 16S rRNA and shotgun metagenomic sequencing identified the principle taxa in the culture as Lactobacillus species. Conclusion The model kefir sample contained thousands of protein fragments released in part by kefir microorganisms and in part by native milk proteases.

The present study evaluated biogenic amine (BA) content during the fermentation period in functional sheep milk yogurts. Four treatments were prepared and assessed: natural (NSY), prebiotic (PreSY), probiotic (ProSY), and synbiotic (SynSY). Biogenic amines (putrescine, cadaverine, spermidine, spermine, and tyramine), proteolysis activity, and pH were measured during each hour of fermentation. Grumixama pulp was added to all formulations as a technological strategy and potential substrate for bacteria during fermentation. The yogurt and probiotic bacteria were viable (≥7 log cfu·mL-1) on d 0. The pH levels of the functional sheep milk yogurts had a more pronounced decrease than did the control of NSY. However, all yogurt samples underwent gradual decreases in pH until final fermentation. Proteolytic activity remained constant in all treatments during fermentation. The NSY, PreSY, ProSY, and SynSY presented the same behavior for all BA, with differences in concentration. Putrescine, cadaverine, and spermidine contents decreased, whereas spermine remained constant and tyramine increased. We conclude that fermentation of functional sheep milk yogurts can produce tyramine.

A major challenge in isolating oligosaccharides from dairy streams is to enrich oligosaccharides while simultaneously reducing the content of simple sugars (mono- and disaccharides) that do not possess the desired prebiotic functions. An integrated approach based on optimized conditions that favor maximum lactose hydrolysis, monosaccharide fermentation and oligosaccharides recovery by nanofiltration was developed. Upon complete lactose hydrolysis and fermentation of the monosaccharides by yeast, nanofiltration of fermented whey permeate from colostrum enabled the recovery of 95% of the oligosaccharides at high purity. While the number of commercially available standards has limited the quantification of only a few sialylated oligosaccharides, the application of both high performance anion-exchange chromatography with pulsed amperometric detection and mass spectrometry provided a complete profile of the final product. Approximately 85% of the oligosaccharides in the final concentrate were sialylated, with the remainder being neutral.

Physicochemical and microbiological changes in yogurts determine their storage and shelf life. Thus, monitoring yogurt quality is essential for consumer acceptance and food safety. However, traditional techniques of yogurt quality analysis are food-destructive, environment polluting, costly, and time-consuming. On the other hand, nondestructive techniques only measure a single quality property, not expressing the yogurt overall quality. In this study, predictive models validated by bootstrapping and cross-validation methods demonstrate the biogenic amine index (BAI) as a nondestructive monitoring system of overall quality during storage. The optical parameter was a strong nondestructive predictor of the BAI for both cow’s milk yogurt, CY (Rv = 0.944; p = 0.007), and goat’s milk yogurt, GY (Rv = 0.909; p = 0.009). For CY, the reduction in the overall acceptability during storage was a strong predictor of the BA index (Rv = 0.869; p

Enzymatic hydrolysis of lactose has been shown to improve the efficiency and selectivity of membrane-based separations toward the recovery of bioactive oligosaccharides. Achieving maximum lactose hydrolysis requires intrinsic process optimization for each specific substrate, but the effects of those processing conditions on the target oligosaccharides are not well understood. Response surface methodology was used to investigate the effects of pH (3.25-8.25), temperature (35-55°C), reaction time (6 to 58 min), and amount of enzyme (0.05-0.25%) on the efficiency of lactose hydrolysis by β-galactosidase and on the preservation of biologically important sialyloligosaccharides (3'-siallylactose, 6'-siallylactose, and 6'-sialyl-N-acetyllactosamine) naturally present in bovine colostrum whey permeate. A central composite rotatable design was used. In general, β-galactosidase activity was favored at pH values ranging from 3.25 to 5.75, with other operational parameters having a less pronounced effect. A pH of 4.5 allowed for the use of a shorter reaction time (19 min), lower temperature (40°C), and reduced amount of enzyme (0.1%), but complete hydrolysis at a higher pH (5.75) required greater values for these operational parameters. The total amount of sialyloligosaccharides was not significantly altered by the reaction parameters evaluated, suggesting specificity of β-galactosidase from Aspergillus oryzae toward lactose as well as the stability of the oligosaccharides at pH, temperature, and reaction time evaluated.