Prediction of indicators of cow diet composition and authentication of feeding specifications of Protected Designation of Origin cheese using mid-infrared spectroscopy on milk

The ability of mid-infrared spectroscopy (MIR) to predict indicators (1) of diet composition in dairy herds and (2) for the authentication of the cow feeding restrictions included in the specification of 2 Protected Designation of Origin (PDO) cheeses (Cantal and Laguiole) was tested on 7,607 bulk milk spectra from 1,355 farms located in the Massif Central area of France. For each milk sample, the corresponding cow diet composition data were obtained through on-farm surveys. The cow diet compositions varied largely (i.e., from full grazing for extensive farming systems to corn silage-based diets, which are typical of more intensive farming systems). Partial least square regression and discriminant analysis were used to predict the proportion of different feedstuffs in the cows' diets and to authenticate the cow feeding restrictions for the PDO cheese specifications, respectively. The groups for the discriminant analysis were created by dividing the data set according to the threshold of a specific feedstuff. They were issued based on the specifications of the restriction of the PDO cheese. The pasture proportion in the cows' diets was predicted by MIR with an coefficient of determination in external validation (R²V) = 0.81 and a standard error of prediction of 11.7% dry matter. Pasture + hay, corn silage, conserved herbage, fermented forage, and total herbage proportion in the cows' diets were predicted with a R²V >0.61 and a standard error of prediction <14.8. The discrimination models for pasture presence, pasture ≥50%, and pasture ≥57% in the cows' diets achieved an accuracy and specificity ≥90%. A sensitivity and precision ≥85% were also observed for the pasture proportion discrimination models, but both of these indexes decreased at increasing thresholds from 0 to 50, and 57% pasture in the cows' diets. An accuracy ≥80% was also observed for pasture + hay ≥72%, herbage ≥50%, pasture + hay ≥25%, absence of fermented herbage, absence of corn silage, and corn silage ≤30% in the cows' diets, but for several models, either the sensitivity or precision was lower than the accuracy. Models built on the simultaneous respect of all the criteria of the feeding restrictions of PDO cheese specifications achieved an accuracy, specificity, sensitivity, and precision >90%. Both the regression and discriminant MIR models for bulk milk can provide useful indicators of cow diet composition and PDO cheese specifications to producers and consumers (farmers, dairy plants).     

SPME-GC-MS结合ROAV分析单菌及复配发酵牛乳中关键性风味物质

采用固相微萃取-气相色谱-质谱联用技术检测分析Streptococcus thermophilus与Lactobacillus delbrueckii subsp.bulgaricus单菌及复配发酵牛乳中的挥发性风味物质,结合相对气味活度值(relative odor activity value,ROAV)探讨发酵牛乳中关键性风味物质。结果表明:本实验共鉴定出100种挥发性风味物质,包括酸类、酮类、醛类、醇类、酯类、烷烃类和芳香族类化合物等。主成分分析表明,表征S.thermophilus单菌发酵乳的关键性风味物质是双乙酰、正壬醛和甲苯;表征L.bulgaricus单菌发酵乳的关键性风味物质是正庚醛、丁酸-2-甲基丙酯和1-庚醇;表征S.thermophilus与L.bulgaricus复配发酵乳的关键性风味物质是乙醛、3-甲基正丁醛、乙偶姻、2-壬酮、2-庚酮、醋酸乙烯酯、碳酸庚基苯基酯、甲酸乙烯酯和2-壬醇。相较于单菌发酵,复配发酵的风味物质组成、各组分相对含量及关键性风味物质均发生改变。     

Replacement of bovine milk with vegetable milk: Effects on the survival of probiotics and rheological and physicochemical properties of frozen fermented dessert

In this study, frozen fermented desserts containing Lactobacillus acidophilus (La‐05; L) and Bifidobacterium bifidum (Bb‐12; B), were made from bovine (W), soya (S), coconut (C) and composite (i.e. combinations of coconut or bovine milks with soya milk) milks. The changes in frozen dessert eating qualities and the survival of added microbes were evaluated. The highest viscosity and melting resistance, and the lowest total sensory scores, were found in the products made using soya milk. After 90‐day storage at ?20 °C, the highest survival percentage of La‐05 was found in the products made using coconut milk (CL); and for Bb‐12, it was found in the products made using soya milk, coconut milk and a 25:75 blend of soya milk and coconut milk respectively ( samples SB, CB and SC3B) SB, SCB and CB samples.     

Factors affecting the clotting properties of sheep milk

A Formagraph was used to test the effects of some of the exogenous factors that can affect the processing properties of milk (pH, soluble calcium, rennet concentration, coagulation temperature), and two of the endogenous factors (protein and fat concentration), on the comparative clotting properties of sheep and cows' milk, namely renneting time (r), rate of firming (k20) and curd consistency (A30). A lower pH decreased r and k20 and increased A30 in both sheep and cows' milk. The addition of calcium chloride did not affect the clotting properties of sheep milk, but in cows' milk it decreased r and k20 and increased A30. Increasing the concentration of rennet decreased r and k20 and increased A30 for both sheep and cows' milk. Increasing the coagulation temperature from 30 to 38 °C decreased r for both sheep and cows' milk, but it decreased k20 and increased A30 only in cows' milk. Increasing the protein concentration decreased r in both sheep and cows' milk; it did not affect k20 of sheep milk, but it decreased that of cows' milk and increased A30 in both milks. Increasing the fat concentration had little effect on r and k20 in either sheep cows' milk, but it decreased A30 in both milks. In general, sheep milk had faster renneting times and rates of firming and greater curd consistency than cows' milk, and its clotting properties tended to be less affected by changes in the clotting conditions. © 2002 Society of Chemical Industry     

Development of a novel milk‐based fermented product fortified with wheat germ

Wheat germ (WG) was mixed with water (1:5), heated (85 °C/15 min), cooled and used to replace 0, 20, 30 and 40% (w/w) of standardised cow's milk (3% fat), supplemented with 2%(w/w) skim milk powder. Yoghurt‐like fermented products were prepared from the different formulations, stored at 7 ± 2 °C for 15 days, and analysed for chemical composition, pH, microbiological quality, texture profile (TPA), viscosity, syneresis and sensory properties. The addition of WG slurry enhanced acid development during fermentation and increased the viscosity of the fermented products. Nutritious milk‐based fermented products of acceptable composition and quality could be prepared from formulations containing 20% (w/w) WG slurry.     

Effect of fermentation temperature on the properties of exopolysaccharides and the acid gelation behavior for milk fermented by Streptococcus thermophilus strains DGCC7785 and St-143

We investigated the effect of fermenting milk with 2 strains (DGCC7785 and St-143) of Streptococcus thermophilus, which are known to produce different types of exopolysaccharide (EPS) structures. The yields and physical properties of these ropy EPS were monitored during the fermentation of milk at different temperatures. We wanted to understand how these types of EPS properties affected yogurt gelation. Reconstituted skim milk was fermented at 33, 39, or 45°C until pH values reached 5.2, 4.9, 4.7, and 4.5. Molar mass of ropy EPS samples was determined using size exclusion chromatography coupled with multiangle laser light scattering. Rheological properties of fermented milk gels were analyzed using small-strain dynamic oscillatory measurements. In both strains, concentrations of ropy EPS increased during fermentation and at all temperatures. Fermentation times, by both strains, were shortest at 45°C and longest at 33°C. For both strains, molar mass of ropy EPS ranged from 2 to 4 × 10⁶ g/mol during fermentation. A major proteinaceous contaminant that was co-isolated with the ropy EPS fraction by our isolation method was identified as a milk-derived phosphoglycoprotein PP3. Increase in fermentation temperature from 33 to 45°C significantly decreased the storage modulus values (from 170 to 41 Pa) for milk gelled by strain DGCC7785, whereas the gels made with St-143 had very low storage modulus values (11–17 Pa) regardless of fermentation temperatures. For both strains, the values of maximum loss tangent in the milk gels increased with fermentation temperature; the maximum loss tangent occurred at higher pH values when milk was fermented by strain DGCC7785. The specific type of EPS produced appeared to be responsible for the differences in yogurt texture rather than the concentration or molar mass of the EPS.     

Selection of starter cultures forthe fermentation of soya milk

The growth of four cultures selected on the basis of their ability to produce lactic acid in soya milk and/or utilize oligosaccharides, namelyStreptococcus thermophilus, Lactobacillus delbrueckiisubspbulgaricus, Lactobacillus fermentiandLactobacillus fermentum, was examined in reconstituted, low fat, spray-dried soya milk powder (12% total solids). The single culture ofS. thermophilusproduced a drop in pH from 6.5 to 4.7 over a 10-h period, and reduced the level of stachyose from 8.5 mg ml^-;1in the original milk to 3.2 mg ml^-;1; after 24 h fermentation, pH fell to 4.5, and the stachyose concentration to 3.0 mg ml^-;1. The paired culture ofS. thermophilusandL. fermentumbehaved in a similar fashion, but with only a slight improvement in stachyose utilization. When yeast extract (0.3%) and glucose (1.0%) were added to the soya milk, acid production by all the cultures increased dramatically, andL. delbrueckiisubspbulgaricusalone or in combination withS. thermophiluslowered the pH of the milk to 4.3 over 10 h. This combination ofS. thermophilusandL. delbrueckiisubspbulgaricuswas considered to be a likely combination for the production of a fermented product from soya milk or modified soya milk, as neitherL. fermentinorL. fermentumwere appreciably more effective in lowering the concentrations of oligosaccharides.     

Effect of probiotic co-cultures on physico-chemical and biochemical properties of small ruminants’ fermented milk

Small ruminants' fermented probiotic milk is an alternative to fermented cows' milk, especially because of the monounsaturated/polyunsaturated fatty acid profiles. The technological and biochemical potential of Bifidobacterium and Lactobacillus co-cultures, with or without inulin, on goats' and ewes' milk was assessed. Microbial stability, lactose consumption, organic acid production, proteolytic parameters and conjugated linoleic acid (CLA) production in situ, were followed in ewes' and goats’ fermented milk (EFM and GFM, respectively) over 21 days at 4 °C; technological feasibility for probiotic fermented milk production was shown. In EFM, all co-cultures presented high viable cell numbers (>7.0 log cfu mL⁻¹) throughout storage, presenting faster acidification capacities and higher CLA isomer levels than in GFM. Inulin had no impact on probiotic growth, yet contributed to storage stability. CLA isomers and proteolysis indices were co-culture dependent traits: for example, co-culture of Bifidobacterium animalis B94 with Lactobacillus acidophilus L10 registered the best CLA-production in GFM.     

Development of a fermented goats' milk containing Lactobacillus rhamnosus: in vivo study of health benefits

BACKGROUND: Lactobacillus rhamnosus CRL1505, a strain of goats' milk origin, is able to stimulate mucosal immunity and protect immunocompetent mice from intestinal and respiratory infections. RESULTS: In this work we developed and characterized a fermented goats' milk containing L. rhamnosus CRL1505, and we demonstrated in a model of immunosuppression in mice that the final dairy product preserves the immunomodulatory properties of the strain. L. rhamnosus CRL1505 survived the manufacturing process of fermented milk and maintained a viability of 10⁶ cfu g^?1 during storage. The fermented goats' milk was accepted by 90.48% of the panelists and was considered as having an acid taste and pleasant aroma. We also demonstrated that the developed product, used as a supplement during the repletion of immunocompromised malnourished mice, was effective in accelerating the recovery of clinical parameters altered by malnutrition and to induce increased resistance against intestinal and respiratory infections. CONCLUSION: Goats' milk fermented with L. rhamnosus CRL1505 could be manufactured as an alternative probiotic dairy product since this new food has the ability to stimulate the common mucosal immune system and to improve defenses against respiratory and intestinal infections. Copyright © 2011 Society of Chemical Industry     

Characterization of the angiotensin-converting enzyme inhibitory activity of fermented milks produced with Lactobacillus casei

Our study assayed angiotensin-converting enzyme (ACE) inhibitory activity and fermentation characteristics of 41 food-originated Lactobacillus casei strains in fermented milk production. Twenty-two of the tested strains produced fermented milks with a high ACE inhibitory activity of over 60%. Two strains (IMAU10408 and IMAU20411) expressing the highest ACE inhibitory activity were selected for further characterization. The heat stability (pasteurization at 63°C for 30 min, 75°C for 25 s, and 85°C for 20 s) and resistance to gastrointestinal proteases (pepsin, trypsinase, and sequential pepsin/trypsinase treatments) of the ACE inhibitory activity in the fermented milks produced with IMAU10408 and IMAU20411 were determined. Interestingly, such activity increased significantly after the heat or protease treatment. Because of the shorter milk coagulation time of L. casei IMAU20411 (vs. IMAU10408), it was selected for optimization experiments for ACE inhibitory activity production. Our results show that fermentation temperature of 37°C, inoculum density of 1 × 10⁶ cfu/g, and fermentation time of 12 h were optimal for maximizing ACE inhibitory activity. Finally, the metabolite profiles of L. casei IMAU20411 after 2 and 42 h of milk fermentation were analyzed by ultra-HPLC electron spray ionization coupled with time-of-flight mass spectrometry. Nine differential abundant metabolites were identified, and 2 of them showed a strong and positive correlation with fermented milk ACE inhibitory activity. To conclude, we have identified a novel ACE inhibitory L. casei strain, which has potential for use as a probiotic in fermented milk production.     

Effects of fermentation by Bifidobacterium bifidum on the rheology and physical properties of ice cream mixes made with cow and vegetable milks

Fermented and nonfermented probiotic ice creams were made by incubating Bifidobacterium bifidum (Bb‐12) culture in ice cream mixes with cow, soya, coconut and composite milks (combinations of coconut or cow milks with soya milk). The changes in ice cream‐eating qualities and physical properties (melting rate, apparent viscosity, hysteresis, fat globule size, zeta potential, microscopic structure and freezing behaviour) were evaluated. In general, fermentation decreased the melting rate and total acceptability of ice creams but increased the apparent viscosity, hysteresis, particle size and freezable water. For fermented ice creams containing composite milk, those containing cow milk showed a higher percentage change than those containing coconut milk in respect of hysteresis, particle size and freezable water; however, the apparent viscosity was not affected.     

Production and properties of a semi-hard cheese made from soya milk

Summary A semi-hard soya cheese, with mean moisture content 61.5%, crude protein 21.8% and fat 2.6%, was produced from reconstituted soya-milk powder using a starter culture of Streptococcus thermophilus and Lactobacillus fermentum . The physical properties of the cheese, as determined with a Texture Profile Analyser , were similar to a cheese made to the same compositional standards from bovine milk. A taste panel of Far Eastern subjects did not find the flavour of the fresh soya cheese acceptable but, when cubes of the cheese (1 cm³) were deep-fried in corn oil, the hedonic rating improved significantly. It is suggested that the cheese could be used as a protein-rich component of a meal, e.g. to replace meat in a stew, or as a 'snack food'.     

Effect of naked oats in the dairy cow's diet on the oxidative stability of the milk fat

Oxidative stability of milk fats from cows offered naked oats- and barley-based diets were compared in shelf-life tests using the Schaal Oven Test at 63°C, and determination of peroxide and thiobarbituric acid values. Milk fat from cows offered the diet containing naked oats, although containing a higher proportion of monounsaturated fatty acids, had a significantly longer oxidation induction period (13 days) than milk fat from cows offered the control (barley-based) diet (9 days). However, sensory testing of the milk fats indicated that a perceptible odour difference was apparent between stored (63°C) and unstored milk fats after 3 days of storage irrespective of the diet fed. It is possible that the odours perceived may have originated from the cows' diets or from hydrolytic rancidity reactions. The difficulties of relating chemical and sensory testing of the oxidative deterioration of milk fat or butter are underlined. © 1998 SCI.     

Production of a yogurt-like product from plant foodstuffs and whey. Sensory evaluation and physical attributes

A mixed substrate composed of soya milk, oat flour and dried cheese whey (820, 110 and 70 g kg^?1 respectively) was heat treated (80°C, 20 min) and fermented using two different yogurt starters. Sensory evaluation was conducted in order to get the basic flavour profile and to assess the acceptability of the product. Unfermented mixed substrate and fermented milk were used as references. Two yogurt starter combinations were used. Some additives such as sugar and calcium were also assessed. The addition of an equal weight of milk to the mixed substrate, and flavours such as strawberry jam or honey, were tried as well. Acceptability of the mixed substrate was increased by fermentation and added sugar, milk and/or flavours. A suitable combination of strains was very important to get good acceptability of the fermented product. Colour and syneresis were also evaluated. Heat treatment had very little influence on the colour of the mixed substrate. The mixture was less white and a little less green than milk. Syneresis was lower than that of a yogurt made from milk with 145 g litre^?1 total solids.     

Screening of a Bacillus subtilis strain producing both nattokinase and milk-clotting enzyme and its application in fermented milk with thrombolytic activity

Bacillus subtilis is a generally recognized as safe probiotic, which is used as a starter for natto fermentation. Natto is a functional food with antithrombus function due to nattokinase. Compared with natto, fermented milk is a more popular fermented food, which is commonly fermented by Lactobacillus bulgaricus and Streptococcus. However, there is no report on B. subtilis–fermented milk. In this study, to produce a functional fermented milk with antithrombus function, a B. subtilis strain (B. subtilis JNFE0126) that produced both nattokinase and milk-clotting enzyme was isolated from traditionally fermented natto and used as the starter for the functional fermented milk. In liquid fermentation culture, the peak values of thrombolytic activity and milk-clotting activity were 3,511 U/mL at 96 h and 874.5 Soxhlet unit/mL at 60 h, respectively. The optimal pH and temperature were pH 7.0 at 40°C for nattokinase and pH 6.5 and 55°C for milk-clotting enzyme, respectively. The thrombolytic activity in the fermented milk reached 215.1 U/mL after 8 h of fermentation. Sensory evaluation showed that the acceptance of the milk fermented by B. subtilis JNFE0126 was similar to the traditional milk fermented by L. bulgaricus and S. thermophilus. More importantly, oral intake of the fermented milk by the thrombosis-model mice prevented the development of thrombosis. Our results suggest that B. subtilis JNFE0126–fermented milk has potential as a novel, functional food in the prevention of thrombosis-related cardiovascular diseases.     

The development of a soya-based yoghurt

The development of a fermented yoghurt-like food from soya is described. Acid produced by the lactic acid bacteria, St. thermophilus and L. bulgaricus , singly and combined, was determined and the effects of supplementation with glucose and yeast extract quantified. A product with acceptable acidity was produced using L. bulgaricus in soya milk supplemented with 1 % glucose and 0.1% yeast extract.     

功能性开菲尔牛奶酒最佳发酵条件的研究

本文利用开菲尔粒中分离的酵母菌和乳球菌采用两步发酵法研制开菲尔牛奶酒。针对影响牛奶酒制品最终品质的三个因素,采用三因素三水平L9(34)正交试验确定了功能性开菲尔牛奶酒的最佳发酵条件。成品开菲尔牛奶酒口感细腻、酸度适中,风味柔和,有浓郁的醇香和酯香味。     

Metabolic footprint analysis of volatile metabolites by gas chromatography-ion mobility spectrometry to discriminate between different fermentation temperatures during Streptococcus thermophilus milk fermentation

Streptococcus thermophilus is widely used in the dairy industry to produce fermented milk. Gas chromatography-ion mobility spectrometry–based metabolomics was used to discriminate different fermentation temperatures (37°C and 42°C) at 3 time points (F0: pH = 6.50 ± 0.02; F1: pH = 5.20 ± 0.02; F2: pH = 4.60 ± 0.02) during S. thermophilus milk fermentation, and differences of fermentation physical properties and growth curves were also evaluated. Fermentation was completed (pH 4.60) after 6 h at 42°C and after 8 h at 37°C; there were no significant differences in viable cell counts and titratable acidity; water-holding capacity and viscosity were higher at 37°C than at 42°C. Different fermentation temperatures affected volatile metabolic profiles. After the fermentation was completed, the volatile metabolites that could be used to distinguish the fermentation temperature were hexanal, butyraldehyde, ethyl acetate, ethanol, 3-methylbutanal, 3-methylbutanoic acid, and 2-methylpropionic acid. Specifically, at 37°C of milk fermentation, branched-chain AA had higher levels, and leucine, isoleucine, and valine were involved in growth and metabolism, which promoted accumulation of some short-chain fatty acids such as 3-methylbutanoic acid and 2-methylpanprooic acid. At 42°C, at 3 different time points during fermentation, ethanol from glycolysis all presented higher levels, including acetone and 3-methylbutanal, producing a more pleasant flavor in the fermented milk. This work provides detailed insight into S. thermophilus fermented milk metabolites that differed between incubation temperatures; these data can be used for understanding and eventually predicting metabolic changes during milk fermentation.     

Metabolomic profile of milk fermented with Streptococcus thermophilus cocultured with Bifidobacterium animalis ssp. lactis,Lactiplantibacillus plantarum,or both during storage

In this study, the microbial interactions among cocultures of Streptococcus thermophilus (St) with potential probiotics of Bifidobacterium animalis ssp. lactis (Ba) and Lactiplantibacillus plantarum (Lp) in fermented milk were investigated during a storage period of 21 d at 4°C, in terms of acidifying activity (pH and titratable acidity), viable counts, and metabolites. A nontargeted metabolomics approach based on ultra-high-performance liquid chromatography coupled with mass spectrometry was employed for mapping the global metabolite profiles of fermented milk. Probiotic strains cocultured with St accelerated milk acidification, and improved the microbial viability compared with the single culture of St. The St–Ba/Lp treatment manifested a higher bacteria viability and acidification ability in comparison with the St–Ba or the St–Lp treatment. Relative quantitation of 179 significant metabolites was identified, including nucleosides, AA, short peptides, organic acids, lipid derivatives, carbohydrates, carbonyl compounds, and compounds related to energy metabolism. The principal component analysis indicated that St treatment and coculture treatments displayed a complete distinction in metabolite profiles, and Lp had a larger effect than Ba on metabolic profiles of fermented milk produced by cofermentation with St during storage. The heat map in combination with hierarchical cluster analysis showed that the abundance of metabolites significantly varied with the starter cultures over the storage, and high abundance of metabolites was observed in either St or coculture samples. The St-Ba/Lp treatment showed relatively high abundance for the vast majority of metabolites. These findings suggest that the profile of the metabolites characterizing fermented milk samples may depend on the starter cultures, and incorporation of probiotics may considerably influence the metabolomic activities of fermented milks.