Contribution oftrans-18∶1 acids from dairy fat to european diets

Twelve commercial samples of French butter, purchased in October–November, and 12 other samples, purchased in May–June, were analyzed with particular attention to theirtrans-octadecenoic acid contents. The isomeric fatty acids were quantitated by a combination of gas-liquid chromatography (GLC) of total fatty acids as isopropyl esters on a polar capillary column (CPSil 88) and of silver nitrate-impregnated thin-layer chromatography followed by GLC of the pooled saturated (used as internal standards) andtrans-octadecenoic acid fractions. Autumn butters contained 3.22±0.44%trans-octadecenoic acids (relative to total fatty acids), whereas those collected during the spring contained 4.28±0.47% (P<0.01). Minimum and maximum values for the two sets of butters were 2.46 (autumn) and 5.10% (spring), respectively. The annual mean value for thetrans-octadecenoic acid content in all butter samples was 3.8% of total fatty acids (ca. 2% for thetrans-11 18∶1 acid). This value allows calculation of the daily individual intake oftrans-octadecenoic acids from dairy products by populations of member states of the European Economic Community (EEC). It varies from 0.57 g (Portugal) to 1.66 g (Denmark). The mean value for the twelve countries of the EEC is 1.16 g/person/d, which is close to data published for the United States. In France, the consumption oftrans octadecenoic acids from dairy fat is higher than that from margarines (ca. 1.5 vs. 1.1 g/person/d).     

Adaptation of bovine milk towards mares’ milk composition by means of membrane technology for koumiss manufacture

This study was carried out to determine the physical, chemical, microbiological and organoleptic properties of koumiss made from bovine milk. The bovine milk was modified according to the composition of mares’ milk using ultrafiltration, microfiltration and nanofiltration. Koumiss made from modified bovine milk and mares’ milk were compared. In order to assess options for a consistent fermentation, a starter culture, instead of the prevailing spontaneous flora in traditional manufacture of koumiss, was used. Key compositional factors modified were the contents of dry matter, mineral, protein and lactose and the casein-to-whey protein ratio. Koumiss made from modified bovine milk and by starter cultures was found to be very similar to koumiss from mares’ milk in terms of pH, titratable acidity, alcohol, proteolytic activity, apparent viscosity, and microbiological composition, when assessed both in the freshly made product and that after 15 days storage at 4°C.     

高压CO_2和乙醇协同沉淀法从牛乳中分离蛋白质的研究

以CO2 为沉淀剂 ,乙醇为CO2 助溶剂 ,考察了高压CO2 和乙醇对牛乳中蛋白质的协同沉淀作用。结果表明 :牛乳中蛋白质的沉淀存在着临界温度和临界压力 ,分别为 3 2℃和2 76MPa ,当体系高于这个临界温度和临界压力时对沉淀过程有利 ;CO2 和乙醇对牛乳中蛋白质的沉淀具有双重作用 ,在水体系中加入乙醇既有助于增加CO2 的溶解度 ,也可以使沉淀的临界温度和临界压力降低     

Nisin expression production from Lactococcus lactis in milk whey medium

BACKGROUND: Nisin is a commercially available bacteriocin produced by Lactococcus lactis ATCC 11454 and used as a natural agent in the biopreservation of food. In the current investigation, milk whey, a byproduct from dairy industries was used as a fermentation substrate for the production of nisin. Lactococcus lactis ATCC 11454 was developed in a rotary shaker (30 °C/36 h/100 rpm) using two different media with milk whey (i) without filtration, pH 6.8, adjusted with NaOH 2 mol L^?1 and without pH adjustment, both autoclaved at 121 °C for 30 min, and (ii) filtrated (1.20 µm and 0.22 µm membrane filter). These cultures were transferred five times using 5 mL aliquots of broth culture for every new volume of the respective media. RESULTS: The results showed that culture media composed of milk whey without filtration supplied L. lactis its adaptation needs better than filtrated milk whey. Nisin titers, in milk whey without filtration (pH adjusted), was 11120.13 mg L^?1 in the second transfer, and up to 1628‐fold higher than the filtrated milk whey, 6.83 mg.L^?1 obtained in the first^t transfer. CONCLUSIONS: Biological processing of milk byproducts (milk whey) can be considered a profitable alternative, generating high‐value bioproducts and contributing to decreasing river disposals by dairy industries. Copyright © 2008 Society of Chemical Industry     

Effect of K-Casein Deglycosylation on the Acid Coagulability of Milk

ABSTRACT: The relationship between the content of N-acetylneuraminic acid residues of micellar K-casein and acid coagulability of milk was investigated. At 30 °C, partial deglycosylation of micellar K-casein does not significantly affect the content of micellar proteins, micellar surface charge, and micellar solvation. Casein micelles modified by the release of part of the N-acetylneuraminic acid residues showed a shorter acid gelation time, a higher rate of gel strengthening, and a higher final firmness. This enhancement in the gelation ability of the neuraminidase-treated casein micelles of milk should appear as the result of increase in number of hydrophobic sites on the surface of casein micelle due to enzymatic deglycosylation of micellar K-casein.     

Growth of a rifampicin-resistant strain of a proteolytic psychrotroph,Pseudomonas fluorescens,in raw and ultra heat-treated milk

Pseudomonas fluorescens UQM2490, resistant to 250 μg rifampicin/ml, was derived from P. fluorescens JC1, a proteolytic psychrotroph isolated from raw milk. Growth of UQM2490 was followed in raw and ultra heat-treated milk, by viable counting on rifampicin-containing agar medium. The growth curves obtained demonstrate slower growth in raw milk than in treated milk and the variation in growth with change in inoculum level. Generation times in ultra heat-treated milk ranged from 9.5 to 14.1 h compared with 9.6 to 33 h in raw milk.     

Human Milk Antibodies against S1 and S2 Subunits from SARS-CoV-2, HCoV-OC43, and HCoV-229E in Mothers with a Confirmed COVID-19 PCR,Viral SYMPTOMS,and Unexposed Mothers

Background: Preexisting immunity to SARS-CoV-2 could be related to cross-reactive antibodies to common human-coronaviruses (HCoVs). This study aimed to evaluate whether human milk antibodies against to S1 and S2 subunits SARS-CoV-2 are cross-reactive to S1 and S2 subunits HCoV-OC43 and HCoV-229E in mothers with a confirmed COVID-19 PCR test, in mothers with previous viral symptoms during COVID-19 pandemic, and in unexposed mothers; Methods: The levels of secretory IgA (SIgA)/IgA, secretory IgM (SIgM)/IgM, and IgG specific to S1 and S2 SARS-CoV-2, and reactive to S1 + S2 HCoV-OC43, and HCoV-229E were measured in milk from 7 mothers with a confirmed COVID-19 PCR test, 20 mothers with viral symptoms, and unexposed mothers (6 Ctl1-2018 and 16 Ctl2-2018) using ELISA; Results: The S2 SARS-CoV-2 IgG levels were higher in the COVID-19 PCR (p = 0.014) and viral symptom (p = 0.040) groups than in the Ctl1-2018 group. We detected a higher number of positive correlations between the antigens and secretory antibodies in the COVID-19 PCR group than in the viral symptom and Ctl-2018 groups. S1 + S2 HCoV-OC43-reactive IgG was higher in the COVID-19 group than in the control group (p = 0.002) but did not differ for the other antibodies; Conclusions: Mothers with a confirmed COVID-19 PCR and mothers with previous viral symptoms had preexisting human milk antibodies against S2 subunit SARS-CoV-2. Human milk IgG were more specific to S2 subunit SARS-CoV-2 than other antibodies, whereas SIgA and SIgM were polyreactive and cross-reactive to S1 or S2 subunit SARS-CoV-2.     

A Newly Developed Synbiotic Yogurt Prevents Diabetes by Improving the Microbiome–Intestine–Pancreas Axis

The prevalence of type 2 diabetes mellitus (T2D) is increasing worldwide, and there are no long-term preventive strategies to stop this growth. Emerging research shows that perturbations in the gut microbiome significantly contribute to the development of T2D, while microbiome modulators may be beneficial for T2D prevention. However, microbiome modulators that are effective, safe, affordable, and able to be administered daily are not yet available. Based on our previous pro- and prebiotic studies, we developed a novel synbiotic yogurt comprised of human-origin probiotics and plant-based prebiotics and investigated its impact on diet- and streptozotocin-induced T2D in mice. We compared the effects of our synbiotic yogurt to those of a commercially available yogurt (control yogurt). Interestingly, we found that the feeding of the synbiotic yogurt significantly reduced the development of hyperglycemia (diabetes) in response to high-fat diet feeding and streptozotocin compared to milk-fed controls. Surprisingly, the control yogurt exacerbated diabetes progression. Synbiotic yogurt beneficially modulated the gut microbiota composition compared to milk, while the control yogurt negatively modulated it by significantly increasing the abundance of detrimental bacteria such as Proteobacteria and Enterobacteriaceae. In addition, the synbiotic yogurt protected pancreatic islet morphology compared to the milk control, while the control yogurt demonstrated worse effects on islets. These results suggest that our newly developed synbiotic yogurt protects against diabetes in mice and can be used as a therapeutic to prevent diabetes progression.     

A new short-path distillation system applied to the reduction of cholesterol in butter and lard

A molecular distillation plant, built particularly to increase the separation efficiency and to obtain safer working conditions, was tested to remove cholesterol from anhydrous butter and lard. A preliminary experiment was carried out with butter to evaluate the fractionation obtained at temperatures between 190 and 250°C and residual pressures between 10⁻³ and 10⁻⁴ torr. A second experiment was carried out at 185°C and at the maximum operational vacuum, evaluating the fractionation achieved within a time scale between 30 and 180 min. Cholesterol was almost completely removed during the second hour with minimal loss of low-molecular weight triglycerides. An experiment was carried out with lard at 250°C and maximum achievable operational vacuum (10⁻⁴ Torr), lasting approximately 6 h, and cholesterol was removed almost completely during the second hour without significant modifications in the triglyceride composition. This situation remained constant throughout the duration of the test.     

Milk fat fractionation today: A review

Although anhydrous milk fat (AMF) has excellent properties, its variable physicochemical properties and its lack of functionality restrict its uses in the food industry. A technology involving dry fractionation of AMF has been developed, and its attributes include selectivity, reliability and general application. Combining two simple and reliable technologies,i.e., multi-step fractionation and blending, it is possible to overcome functionality problems and the seasonal variations of AMF. Lecture presented at the joint meeting of the International Society for Fat Research and the American Oil Chemists’ Society in Toronto, May 10, 1992.