Effect of addition of CO₂ to raw milk on quality of UHT-treated milk

The objective of this study was to evaluate the effect of addition of CO(2) to raw milk on UHT milk quality during storage. Control milk (without CO(2) addition) and treated milk (with CO(2) addition up to pH 6.2) were stored in bulk tanks at 4°C for 6d. After storage, both samples were UHT processed using indirect heating (140°C for 5s). Samples were aseptically packed in low-density polyethylene pouches and stored in the dark at room temperature. Raw milk was evaluated upon receipt for physicochemical composition, proteolysis, lipolysis, standard plate count, psychrotrophic bacteria, and Pseudomonas spp. counts, and after 6d of storage for proteolysis, lipolysis, and microbial counts. After processing, UHT milk samples were evaluated for physicochemical composition, proteolysis, and lipolysis. Samples were evaluated for proteolysis and lipolysis twice a month until 120d. Peptides from pH 4.6-soluble N filtrates were performed by reversed-phase HPLC after 1 and 120d of storage. A split-plot design was used and the complete experiment was carried out in triplicate. The results were evaluated by ANOVA and Tukey's test. After 6d of storage, CO(2)-treated raw milk kept its physicochemical and microbiological quality, whereas the untreated milk showed significant quality losses. A significant increase in proteolysis occurred during 120d of storage in both treatments, but the increase occurred 1.4 times faster in untreated UHT milk than in CO(2)-treated UHT milk. In both UHT milks, the proteolysis was a consequence of the action of plasmin and microbial proteases. However, the untreated UHT milk showed higher microbial protease activity than the treated UHT milk. The addition of CO(2) to the raw milk maintained the quality during storage, resulting in UHT milk with less proteolysis and possibly longer shelf life, which is usually limited by age gelation of UHT milk.     

Addition of milk or caseinophosphopeptides to fruit beverages to improve iron bioavailability?

A study has been made of the influence of caseinophosphopeptides (CPPs) added to a fruit beverage versus milk based fruit beverages upon iron retention, transport and uptake, using a combined simulated gastrointestinal digestion/Caco-2 cell system. Grape concentrate, orange concentrate, and apricot puree were used for sample formulation. Eight samples were assayed with/without added Fe sulphate (3 mg/100 ml fruit beverage) and/or added Zn sulphate (1.6 mg/100 ml fruit beverage), with/without skimmed milk (11% v/v). The addition of milk to fruit beverages exerted a positive effect on iron retention, transport and uptake versus fruit beverages, and this effect was greater than that of CPPs added to soluble fractions of fruit beverages. The addition of CPPs to soluble fractions of fruit beverages improved iron transport. Iron supplementation increased Fe retention, transport and uptake – the effect being more notable in samples with milk. Zinc supplementation did not affect Fe retention, transport or uptake.     

Novel milk–juice beverage with fermented sheep milk and strawberry (Fragaria × ananassa): Nutritional and functional characterization

This study was aimed at developing a new functional fermented beverage manufactured with semi-skimmed sheep milk and strawberry pulp (Fragaria × ananassa Duch.) and commercial prebiotic ingredients. We also compared the performance of the yogurt starter cultures and a Lactobacillus plantarum strain (CECT_8328) with potential probiotic properties. We assessed the nutritional profile, bioactivity compounds, viability of lactic acid bacteria during storage, and survival of L. plantarum after in vitro simulated digestion during the storage period. The lactic acid bacteria were viable throughout the storage period, but only L. plantarum maintained good viability after simulated digestion. Nevertheless, neither inulin nor potato starch increased bacterial viability. The fermented semi-skimmed sheep milk strawberry beverages we developed are good sources of minerals and proteins.     

Brominated and fluorinated organic pollutants in the breast milk of first-time Irish mothers: is there a relationship to levels in food?

Brominated flame retardants – polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), hexabromocyclododecane (HBCD) and others – have been measured in 11 pooled breast milk samples from 109 first-time mothers in Ireland. Additionally, the study has measured levels of polybrominated dibenzo-p-dioxins and furans (PBDD/Fs), mixed halogenated dioxins (PXCC/Fs) and biphenyls (PXBs), polychlorinated naphthalenes (PCNs) and perfluoroalkylated substances (PFAS) in these samples. The mean sum of 19 PBDEs including BDE-209 was 4.85 ng g^?1 fat, which is comparable with that found in other European countries. BDE-47, BDE-153, BDE-209, BDE-99 and BDE-100 were found at the highest concentrations. The only PBBs detected consistently were BB-77, BB-126 and BB-153, with highest concentrations being found for BB-153 (mean = 0.13 ng g^?1 fat). The mean sum of HBCD enantiomers was 3.52 ng g^?1 fat, with α-HBCD representing over 70% of the total. Of the other brominated flame retardants – tetrabromobisphenol-A (TBBP-A), hexabromobenzene (HBB), decabromodiphenylethane (DBDPE) and bis(2,4,6-tribromophenoxyethane) (BTBPE) – examined, only TBBP-A was detected above the limit of detection (LOD), in two of the 11 pools analysed. All measured PBDF congeners were observed (at 0.02–0.91 pg g^?1 fat), but 2,3,7,8-tetrabromo-dibenzodioxin (TeBDD) was the only PBDD detected, with a mean concentration of 0.09 pg g^?1 fat. The occurrence of the mixed chlorinated/brominated dibenzodioxins, dibenzofurans and biphenyls, 2-B-3,7,8-CDD, 2,3-B-7,8-CDF, 4-B-2,3,7,8-CDF, PXB 105, PXB 118, PXB 126 and PCB 156 in breast milk in the current study may indicate that levels of these contaminants are increasing in the environment. Polychlorinated naphthalenes were detected in all samples, but not perfluorooctane sulfonate (PFOS) and other PFAS. The pattern of occurrence of these brominated and fluorinated persistent organic pollutants (POPs) in Irish breast milk shows a general relationship to their occurrence in food, as reported in a number of surveillance studies carried out by the Food Safety Authority of Ireland.     

Johne's disease and milk: do consumers need to worry?

Mycobacterium paratuberculosis, an acid-fast bacillus that causes enteritis in ruminants, has been suggested as an etiological agent of Crohn's disease in humans. The mode of transmission is unclear; however, some evidence suggests that humans may become infected via contaminated milk. Currently, it is not known whether commercial pasteurization effectively kills M. paratuberculosis in contaminated raw milk. Using a laboratory-scale pasteurizer unit designed to simulate the high-temperature, short-time method (72 degrees C, 15 sec) currently used by commercial dairies, we previously demonstrated that treatment of raw milk inoculated with 10(4) to 10(6) cfu of M. paratuberculosis/ml reduced numbers to an undetectable level. However, M. paratuberculosis is an intracellular pathogen that resides within the macrophages of the host and evades destruction. We subsequently performed further experiments examining heat treatment of milk inoculated with mammary gland macrophages containing ingested M. paratuberculosis. Heat treatment of these samples under high-temperature, short-time conditions demonstrated that the macrophage does not protect the organism because we were unable to recover any viable M. paratuberculosis from the samples. Conversely, other researchers have demonstrated that a residual population of M. paratuberculosis may survive heat treatment of milk. In addition, a recent news report stated that viable M. paratuberculosis organisms have been cultured from retail-ready milk in Ireland. A summary of past and current studies concerning this issue along with a discussion of methodologies used to recover M. paratuberculosis from experimentally inoculated milk will be presented in this paper.     

Effect of CSN1S1-CSN3 (α(S1)-κ-casein) composite genotype on milk production traits and milk coagulation properties in Mediterranean water buffalo

The aim of this study was to estimate effects of CSN1S1-CSN3 (α_S1-κ-casein) composite genotypes on milk production traits and milk coagulation properties (MCP) in Mediterranean water buffalo. Genotypes at CSN1S1 and CSN3 and coagulation properties [rennet clotting time (RCT), curd firming time (K₂₀), and curd firmness (A₃₀)] were assessed by reversed-phase HPLC and computerized renneting meter analysis, respectively, using single test-day milk samples of 536 animals. Alternative protein variants of α_S1-CN and κ-CN were detected by HPLC, and identification of the corresponding genetic variants was carried out by DNA analysis. Two genetic variants were detected at CSN1S1 (A and B variants) and 2 at CSN3 (X1 and X2 variants). Statistical inference was based on a linear model including the CSN1S1-CSN3 composite genotype effect (7 genotypes), the effects of herd-test-day (8 levels), and a combined days in milk (DIM)-parity class. Composite genotype AB-X2X2 was associated with decreased test-day milk yield [?0.21 standard deviation (SD) units of the trait] relative to genotype BB-X2X2. Genotypes did not affect milk protein content, but genotype AB-X1X1 was associated with increased fat content compared with genotype BB-X2X2 (+0.28 SD units of the trait) and AB-X1X1 (+0.43 SD units of the trait). For RCT, the largest difference (+1.91 min; i.e., 0.61 SD units of the trait) was observed between genotype AA-X1X2 and AB-X1X1. Direction of genotype effects on K₂₀ was consistent with that for RCT. The maximum variation in K₂₀ due to genotype effects (between AA-X1X2 and AB-X1X1 genotypes) was almost 0.9 SD units of the trait. Magnitude of genotype effects was smaller for A₃₀ than for RCT and K₂₀, with a maximum difference of 0.5 SD units of the trait between genotype AA-X1X2 and AA-X1X1. The B allele at CSN1S1 was associated with increased RCT and K₂₀ and with weaker curds compared with allele A. Allele X2 at CSN3 exerted opposite effects on MCP relative to CSN1S1 B. Because of linkage disequilibrium, allele B at CSN1S1 and allele X2 at CSN3 tend to be associated and this likely makes their effects cancel each other. This study indicates a role for casein genes in variation of MCP of buffalo milk. Further studies are necessary to estimate the effects of casein genetic variants on variation of cheese yield.     

Determination of alkylphenol residues in breast and commercial milk by solid-phase extraction and gas chromatography–mass spectrometry

This study presents a feasible and sensitive method to determine alkylphenol residues (i.e., 4-t-octylphenol (4-t-OP) and the isomers of 4-nonylphenols (4-NPs)) in breast milk samples and commercial cow milk products. The matrix interference associated with the constituents in the milk was reduced by extraction with n-hexane and dilution with 50% methanolic solution (v/v, methanol/water), then followed by the Oasis-HLB SPE extraction. The analytes were determined by a GC–MS system in full-scan and selected ion monitoring modes simultaneously. Limit of quantitation was less than 0.05 ng/g in a 20 g (wet weight) milk sample. The 4-NPs were detected in 19 of the 20 breast milk samples at concentrations ranging from 1.7 to 11.6 ng/g, while 4-t-OP was detected in 8 samples at concentrations ranging from 0.4 to 1.1 ng/g. The 4-NPs were detected in all the testing commercial cow milk products at concentrations ranging from 2.9 to 8.8 ng/g.     

Occurrence and levels of mycotoxins and their metabolites in human breast milk associated to dietary habits and other factors: A systematic literature review, 1984–2015

BackgroundMany studies around the world reported the occurrence of many mycotoxins and their metabolites in human breast milk. However the contamination by aflatoxin M1 and ochratoxin A were the most investigated by several countries.Scope and approachTo scrutinize all papers reporting quantitative data on the prevalence and the levels of mycotoxins and their metabolites in breast milk, also the circumstances of exposure.A systematic literature search in Pubmed, Science direct and Google scholar databases were performed to identify relevant studies, published in English from 1984 through May 2015.Key findings and conclusion63 studies met the inclusion criteria and assessed the occurrence of 29 mycotoxins & their metabolites in breast milk, regarding 7194 subjects of 31 countries. The maternal dietary habits, the socio demographic status of the mother, the seasonal variations and the sensitivity of the analytical method were the factors related to the high concentrations of AFM1 and OTA in breast milk.Studies where contamination exceeds maximum limits and exhibit real risk of public health were highlighted.     

Effects of the circadian rhythm on milk composition in dairy cows: Does day milk differ from night milk?

Metabolism in most organisms can show variations between the day and night. These variations may also affect the composition of products derived from livestock. The aim of the present study was to investigate the difference in composition between the day milk and night milk of dairy cows. Ten multiparous Holstein cows (milk yield = 25.2 ± 5.00 kg/d) were randomly selected during mid lactation. Milk samples were collected at 0500 h (“night milk”) and 1500 h (“day milk”) and analyzed to determine their composition. Mid-infrared spectroscopy was used to analyze macronutrient content of milk. Metabolomics and lipidomics were used to detect and analyze small molecules and fatty acids, respectively. An automatic biochemical analyzer and ELISA kits were used to determine biochemical indicators, as well as antioxidant and immune parameters in the milk. Though milk fat, protein, lactose, and total milk solids were not different between day milk and night milk, small molecules, metabolites and lipids, and hormones and cytokines differed between day milk and night milk. Regarding biochemical and immune-related indicators, the concentrations of malondialdehyde, HSP70, and HSP90 in night milk were lower than that in day milk. However, interferon-γ levels were higher in night milk. Additionally, night milk was naturally rich in melatonin. Lipidomics analyses showed that the levels of some lipids in night milk were higher than those in day milk. Metabolomics analyses identified 36 different metabolites between day milk and night milk. Higher concentrations of N-acetyl-d-glucosamine, cis-aconitate, and d-sorbitol were observed in day milk. However, the other 33 metabolites analyzed, including carbohydrates, lipids, AA, and aromatic compounds, showed lower concentrations in day milk than in night milk. The present findings show that the composition of night milk differs considerably from that of day milk. Notable changes in the circadian rhythm also altered milk composition. These results provide evidence to support the strategic use and classification of day milk and night milk.     

Assessment of cadmium levels in human breast milk and the affecting factors: A systematic review, 1971–2014

Background: This is a first systematic review summarizing 43 years of research from 36 countries for the assessment of cadmium in breast milk, a suitable matrix in human biomonitoring. Objectives: To report from the published literature the levels of cadmium in breast milk, and the affecting factors causing increase in cadmium concentrations. In addition, to gather several quantitative data that might be useful to evaluate the international degrees of maternal and infant exposure. Methods: We reviewed the literature published between 1971 and 2014, available on Pubmed, Science Direct, and Google Scholar, reporting quantitative data about cadmium levels in human breast milk. Information about the aim of the study, name of the country, period of collection of samples, size of samples, sampling method, time of lactation, mother's age, area of residence, cadmium concentration, and other data were extracted. Results: Sixty-seven studies were selected and included in this systematic review. Some concentrations greatly exceed the limit set by the World Health Organization (WHO); however, about 50% of the studies had less than 1 µg/L cadmium concentration (recommended by the WHO); as well as many factors have shown their implication in breast milk contamination. Conclusions: Breast milk is a pathway of maternal excretion of cadmium. It is also a biological indicator of the degree of environmental pollution and cadmium exposure of the lactating woman and the nourished infant. Therefore, preventive measures and continuous monitoring are necessary.     

Effects of β-κ-casein (CSN2-CSN3) haplotypes and β-lactoglobulin (BLG) genotypes on milk production traits and detailed protein composition of individual milk of Simmental cows

The aim of this study was to investigate the effects of CSN2-CSN3 (β-κ-casein) haplotypes and BLG (β-lactoglobulin) genotypes on milk production traits, content of protein fractions, and detailed protein composition of individual milk of Simmental cows. Content of the major protein fractions was measured by reversed-phase HPLC in individual milk samples of 2,167 cows. Protein composition was measured as percentage of each casein (CN) fraction to total CN and as percentage of β-lactoglobulin (β-LG) to total whey protein. Genotypes at CSN2, CSN3, and BLG were ascertained by reversed-phase HPLC, and CSN2-CSN3 haplotype probabilities were estimated for each cow. Traits were analyzed by using a linear model including the fixed effects of herd-test-day, parity, days in milk, and somatic cell score class, linear regressions on haplotype probabilities, class of BLG genotype, and the random effect of the sire of the cow. Effects of haplotypes and BLG genotypes on yields were weak or trivial. Genotype BB at BLG and haplotypes carrying CSN2 B and CSN3 B were associated with increased CN content and CN number. Haplotypes including CSN3 B were associated with increased κ-CN content and percentage of κ-CN to total CN and with decreased percentages of α_S1- and γ-CN to total CN. Allele CSN2 B had the effect of increasing β-CN content and decreasing content of α_S1-CN. Haplotypes including allele CSN2 A¹ exhibited decreased β-, α_S2-, and γ-CN concentrations and increased α_S1- and κ-CN contents, whereas CSN2 I had positive effects on β-CN concentration and trivial effects on content of other protein fractions. Effects of haplotypes on CN composition were similar to those exerted on content of CN fractions. Allele BLG A was associated with increased β-LG concentration and percentage of β-LG to total whey protein and with decreased content of other milk proteins, namely β-CN and α_S1-CN. Estimated additive genetic variance for investigated traits ranged from 14 to 39% of total variance. Increasing the frequency of specific genotypes or haplotypes by selective breeding might be an effective way to change milk protein composition.     

Technological characterization of lactic acid bacteria isolated from Armada cheese (a Spanish goats’ milk cheese)

Thirty-one strains of lactic acid bacteria (LAB) isolated from Armada cheese, Sobado variety, (eight strains of Lactococcus lactis subsp. lactis, four strains of Lactococcus lactis subsp. cremoris, two strains of L. lactis subsp. lactis biovar. diacetylactis, two strains of Leuconostoc mesenteroides subsp. mesenteroides, two strains of Leuconostoc mesenteroides subsp. dextranicum, five strains of Lactobacillus plantarum, six strains of Lactobacillus casei subsp. casei and two strains of Lactobacillus brevis) were screened for their acidifying capacity and enzymatic activity, that included the rapid API-ZYM system, the proteolytic activity, the amino-, di-, and carboxypeptidase activity and the caseinolytic activity. The strains of L. lactis subsp. lactis exhibited the highest acidifying and proteolytic activity. Lipase and esterase activity was practically non-existent for lactococci and lactobacilli; a certain esterase activity was observed among leuconostoc. The highest aminopeptidase activity was demonstrated by the cell-free extract (CFE) of some strains of L. plantarum, L. casei subsp. casei and L. mesenteroides subsp. dextranicum. The CFEs of L. lactis subsp. cremoris and L. lactis subsp. lactis possessed carboxypeptidase and dipeptidase activities, at levels depending on the strain. Appreciable caseinolytic activity was detected for the CFE of L. plantarum and those some lactococci.     

Characterisation of milk samples with various whey protein contents by pyrolysis–mass spectrometry (Py–MS)

Different milk samples and their 2, 5 and 10% mixtures with ‘artificial’ or natural whey protein were analysed by means of pyrolysis–mass spectrometry (Py–MS). Py–MS followed by multivariate analysis of the resulting mass spectra enabled the determination of the whey protein addition in milk samples. Obtained results showed that this determination seems not to be influenced by the fat content and freezing of the samples, as well as a dilution of the samples. ©     

Effects of α s1-casein (CSN1S1) and κ-casein (CSN3) genotypes on milk coagulation properties in Murciano-Granadina goats

The effects of the caprine α s1-casein (CSN1S1) polymorphisms on milk quality and cheese yield have been widely studied in French and Italian goat breeds. Much less is known about the consequences of κ-casein (CSN3) genotype on the technological and coagulation properties of goat milk. In the current study, we have performed an association analysis between polymorphisms at the goat CSN1S1 and CSN3 genes and milk coagulation (rennet coagulation time, curdling rate and curd firmness) and technological (time to cutting of curd and cheese yield) properties. In this analysis, we have included 193 records from 74 Murciano-Granadina goats (with genotypes constituted by different combinations of alleles B, E and F of the gene CSN1S1 and alleles A and B of the gene CSN3) distributed in three herds, which were collected bimonthly during a whole lactation. Data analysis, using a linear mixed model for repeated observations, revealed significant associations between CSN1S1 genotypes and the rate of the curdling process. In this way, milk from EE goats had a significantly higher curdling rate than milk from BB individuals (P<0?·05). Contrary to previous experiments performed in French breeds, cheese yield was not significantly different in BB, EE and EF goats. Moreover, we have shown that CSN3 genotype has a significant effect on the rennet coagulation time (BB>AB, P<0?·05) but not on cheese yield. No interaction between the CSN1S1 and CSN3 genotypes was observed.