Differences in Aroma Metabolite Profile, Microstructure, and Rheological Properties of Fermented Milk Using Different Cultures.

Texture and flavour are the key attributes determining sensory quality and are highly affected by starter cultures. A selection of phenotypic strains is needed to create diverse texture and flavour to meet consumers' preferences. In this study, the use of five lactic acid bacteria strains in the production of fermented milk, along with the metabolite profiles, microstructure, and rheological properties of the fermented milk samples, was investigated. Our results showed that Lactobacillus helveticus (LH) and Streptococcus thermophilus (ST) had a stronger acidification during fermentation but resulted in products with a coarser protein network compared to Lactococcus lactis (BL1) and Leuconostoc mesenteroides (CL3). Milk fermented by LH had the highest viscosity and exopolysaccharide concentration, while milk fermented by ST had the highest concentration of diacetyl. Although Leuconostoc pseudomesenteroides (CL3ST) had a minimal acidification capability, it produced high levels of ethyl-derived compounds associated with sweet, fruity, and floral fragrances. The results demonstrated that LH and ST could be used as starter cultures targeting fermented milks with different viscosities, while BL1, CL3, and CL3ST are suitable as adjunct cultures to impact different acidic sharpness and flavour notes.

Nisin E Is a Novel Nisin Variant Produced by Multiple Streptococcus equinus Strains.

Nisin A, the prototypical lantibiotic, is an antimicrobial peptide currently utilised as a food preservative, with potential for therapeutic applications. Here, we describe nisin E, a novel nisin variant produced by two Streptococcus equinus strains, APC4007 and APC4008, isolated from sheep milk. Shotgun whole genome sequencing and analysis revealed biosynthetic gene clusters similar to nisin U, with a unique rearrangement of the core peptide encoding gene within the cluster. The 3100.8 Da peptide by MALDI-TOF mass spectrometry, is 75% identical to nisin A, with 10 differences, including 2 deletions: Ser29 and Ile30, and 8 substitutions: Ile4Lys, Gly18Thr, Asn20Pro, Met21Ile, His27Gly, Val32Phe, Ser33Gly, and Lys34Asn. Nisin E producing strains inhibited species of Lactobacillus, Bacillus, and Clostridiodes and were immune to nisin U. Sequence alignment identified putative promoter sequences across the nisin producer genera, allowing for the prediction of genes in Streptococcus to be potentially regulated by nisin. S. equinus pangenome BLAST analyses detected 6 nisin E operons across 44 publicly available genomes. An additional 20 genomes contained a subset of nisin E transport/immunity and regulatory genes (nseFEGRK), without adjacent peptide production genes. These genes suggest that nisin E response mechanisms, distinct from the canonical nisin immunity and resistance operons, are widespread across the S. equinus species. The discovery of this new nisin variant and its immunity determinants in S. equinus suggests a central role for nisin in the competitive nature of the species.

Active Packaging for the Extended Shelf-Life of Meat: Perspectives from Consumption Habits, Market Requirements and Packaging Practices in China and New Zealand.

Active packaging (AP) has been developed to improve the safety, quality and integrity of food, and minimise food waste, while its application in meat is scarce. This review aims to describe meat production and consumption culture in China and New Zealand to provide the context for packaging innovation requirements, focusing on the emerging opportunities for AP to be used for the improvement of the shelf-life of pre-rigor, aged, and frozen-thawed meat products. Sustainable polymers utilised in the manufacturing of AP, manufacturing techniques, the release mechanisms of actives, and legal and regulatory constraints are also discussed. Diverse market compositions and consumption cultures in China and New Zealand require different packaging solutions to extend the shelf-life of meat. AP containing antimicrobials, moisture regulating agents, and antioxidants may be used for pre-rigor, dry- and wet-aged products and in improving the quality and shelf-life of frozen-thawed meat. Further innovations using sustainably produced polymers for AP, along with incorporating active compounds of multiple functions for effectively improving meat quality and shelf-life are necessary. Challenges remain to resolve issues with scaling the technology to commercially relevant volumes as well as complying with the rigorous legal and regulatory constraints in various countries.

Changes in Human Milk Fat Globule Composition Throughout Lactation: A Review.

There has been a growing interest in understanding how the relative levels of human milk fat globule (MFG) components change over the course of lactation, how they differ between populations, and implications of these changes for the health of the infant. In this article, we describe studies published over the last 30 years which have investigated components of the MFG in term milk, focusing on changes over the course of lactation and highlighting infant and maternal factors that may influence these changes. We then consider how the potential health benefits of some of the milk fat globule membrane (MFGM) components and derived ingredients relate to compositional and functional aspects and how these change throughout lactation. The results show that the concentrations of phospholipids, gangliosides, cholesterol, fatty acids and proteins vary throughout lactation, and such changes are likely to reflect the changing requirements of the growing infant. There is a lack of consistent trends for changes in phospholipids and gangliosides across lactation which may reflect different methodological approaches. Other factors such as maternal diet and geographical location have been shown to influence human MFGM composition. The majority of research on the health benefits of MFGM have been conducted using MFGM ingredients derived from bovine milk, and using animal models which have clearly demonstrated the role of the MFGM in supporting cognitive and immune health of infants at different stages of growth and development.

Extracellular Polysaccharide Extraction from Streptococcus thermophilus in Fermented Milk.

Lactic acid bacteria such as Streptococcus thermophilus are known to produce extracellular polysaccharide (EPS) in fermented foods that enhance the creaminess and mouthfeel of the product, such as yogurt. Strains producing larger amounts of EPS are highly sought-after, and therefore, robust and accurate quantification methodologies are important. This study found that two commonly used methodologies significantly underestimated the amount of EPS produced as measured using a milk matrix. To this end, a proteolytic step was implemented prior to EPS extraction (Method C). An initial proteolytic step using xanthan gum-spiked milk significantly increased recovery yield to 64%, compared to 27.8% for Method A and 34.3% for Method B. Method C showed no improvement when assessed using a chemically defined medium. Method C was further validated using three strains of S. thermophilus with varying EPS-production capabilities (STLOW, STMID, STHIGH). Overall, Method C demonstrated significant improvements in the EPS extraction yield for all three S. thermophilus strains in fermented milk. On average, Method C improved isolation yield by ∼3- to 6-fold compared with Method A and by ∼2- to 3-fold compared with method B. There were no significant differences between samples when they were grown in a chemically defined medium, highlighting the importance of a proteolytic step specifically for fermented milk samples. In commercial applications, accurate quantification of EPS-production is an important aspect when finding new strains. IMPORTANCE Extracellular polysaccharide (EPS) production by milk-fermenting microorganisms is a highly sought-after trait in improving the perceived thickness, creaminess, and mouthfeel of yogurt. Streptococcus thermophilus are commonly isolated and their EPS production is quantified in the search for higher-producing strains. In this study, we demonstrated that two commonly used methods for isolating EPS from milk samples significantly underestimated the true amount of EPS present. We demonstrated that the addition of a proteolytic step prior to EPS extraction isolated over 2-fold more EPS than identical samples processed using the traditional protocols. We further validated this method in fermented milk samples from three strains of S. thermophilus that included a low-, mid-, and high-EPS producing strain. Again, we showed significant improvements in EPS isolation using a proteolytic step. In the search for new S. thermophilus strains with enhanced EPS production, accurate quantification in an optimal medium is essential.

Nucleotides: an updated review of their concentration in breast milk.

Our knowledge about the complexity of human milk, in particular fatty acid, protein, and oligosaccharide profiles, has increased considerably in recent years. However, little attention has been paid to nucleotides, which account for ∼2% to 5% of the nonprotein nitrogen fraction of breast milk and provide important cellular and metabolism functions for the infant. We examined literature published in the past 25 years to provide an updated review of concentrations of nucleotides in breast milk across lactational stages in mothers around the world. The free mononucleotides found in highest concentrations in breast milk are, from highest to lowest in the order of cytidine 5'-monophosphate, uridine 5'-monophosphate, and adenosine 5'-monophosphate, guanosine 5'-monophosphate, and inosine 5'-monophosphate. Levels of nucleotides varied considerably amongst individual mothers and with stage of lactation. They could be further influenced by time of day and season and the mother's diet. Levels of free nucleotides varied between studies undertaken in different regions; however, in studies that measured total potentially available nucleotides levels, regional differences were not apparent. Some studies report higher amounts in colostrum and transition milk compared with mature milk, whereas other studies report the converse. Recently, clinical studies showed that there are benefits to supplement nucleotides in infant formula. Although comparing data in the literature remains a challenge because of different milk collection methodologies and measurement protocols used by different studies, the information may provide insights for designing of formula products for infant at different stages of development.

Postprandial lipemic response in dairy-avoiding females following an equal volume of sheep milk relative to cow milk: A randomized controlled trial.

Background: Sheep milk (SM) is an alternate dairy source, which despite many similarities, has both compositional and structural differences in lipids compared to cow milk (CM). Studies are yet to examine the apparent digestibility of SM lipids, relative to CM, and the potential impact on the plasma lipidome. Objective: To determine the response of the circulatory lipidome to equal volume servings of SM and CM, in females who avoid dairy products. Method: In a double-blinded, randomized, cross-over trial, self-described dairy avoiding females (n = 30; 24.4 ± 1.1 years) drank SM or CM (650 mL; 33.4 vs. 21.3 g total lipid content; reconstituted from spray dried milk powders) following an overnight fast. Blood samples were collected at fasting and at regular intervals over 4 h after milk consumption. The plasma lipidome was analyzed by LC-MS and fatty acids were quantified by GC-FID. Results: The overall postprandial triglyceride (TG) response was similar between SM and CM. TG concentrations were comparable at fasting for both groups, however they were higher after CM consumption at 30 min (interaction milk × time p = 0.003), well before any postprandial lipemic response. This was despite greater quantities provided by SM. However, there were notable differences in the postprandial fatty acid response, with SM leading to an increase in short- and medium-chain fatty acids (MCFAs) (C6:0, C8:0, and C10:0) and several long-chain fatty acids (LCFAs) (C18:1 t11, c9, t11-CLA, and C20:0; interaction time × milk p < 0.05). This corresponded to a greater postprandial response for medium chain triglycerides (MCTs) C10:0, including TG(10:0/14:0/18:1), TG(16:0/10:0/12:0), and TG(16:0/10:0/14:0) (interaction time × milk p < 0.05). Conclusions: Despite a higher fat content, SM ingestion resulted in a greater circulating abundance of MCTs, without increasing total postprandial triglyceride response, when compared to CM. The greater abundance and postprandial appearance of MCTs may provide advantageous metabolic responses in children and adults. Unique identifier and registry: U1111-1209-7768; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375324.

Objective Measurements Associated with the Preferred Eating Qualities of Fermented Salamis.

The development of new food products can be expedited by understanding the physicochemical attributes that are most relevant to consumers. Although many objective analyses are possible, not all are a suitable proxy to serve as quality markers associated with sensory preferences. In this work, we selected nine candidate laboratory assays to use on six commercial salamis, which were also eaten and informally described by a consumer discussion group familiar with China-sourced meat products. Several objective measures were strongly related to the flavour perceptions: (i) texture: instrumental texture values, fat release at oral temperature and fat saturation ratios, (ii) aroma: volatile compounds (e.g., alcohols and esters) associated with microbial fermentation and spices (terpenes and sulphur compounds) and (iii) taste: kokumi taste receptor responses. The fat released at oral temperature was associated with unsaturated fatty acids (r = 0.73). However, there was less explanatory worth for associations between sensory perceptions and proximate composition, water activity, pH or L*, a*, b* colourimetry.

Tempering governs the milk fat crystallisation and viscoelastic behaviour of unprocessed and homogenised creams.

The crystallisation behaviour of milk fat plays an important role in the functionality and sensory properties of fat-rich dairy products. In this study, we investigated the impact of tempering to 25 °C on the viscoelastic properties, particle size and thermal behaviour of 20% w/w unprocessed and homogenised creams prepared from bovine milk. The crystallisation properties were examined by synchrotron X-ray diffraction (XRD) at small (SAXS) and wide angle (WAXS) and differential scanning calorimetry (DSC). Oscillation rheology was performed to characterise the cream's viscoelastic properties. Homogenisation (35 MPa) reduced the average droplet size from 4.4 to 1.3 µm. After 24 h storage at 4 °C, milk fat structures showed triacylglycerol (TAG) 2L and 3L(001, 002, 003, 005) lamellar stacking orders associated predominantly with the α and ß' polymorphic forms. Tempering to 25 °C induced the complete melting of the 3L crystals and led to an irreversible loss in the elastic modulus (G') and a reduction in the viscous modulus (G'') once returned to refrigerated conditions, due to changes in the particle-particle interactions and structure of the reformed milk fat crystals. The results demonstrate that crystallisation behaviour of milk fat is influenced by droplet size and the rearrangement of triacylglycerol (TAG) upon tempering, and lead to changes in the viscoelastic behaviour of dairy products containing a high level of milk fat.

Changes in HMO Concentrations throughout Lactation: Influencing Factors, Health Effects and Opportunities.

Human milk oligosaccharides (HMOs) are important functional biomolecules in human breast milk. Understanding the factors influencing differences in HMO composition and changes in their concentration over lactation can help to design feeding strategies that are well-adapted to infant's needs. This review summarises the total and individual concentration of HMOs from data published from 1999 to 2019. Studies show that the HMO concentrations are highest in colostrum (average 9-22 g/L), followed by slightly lower concentrations in transitional milk (average 8-19 g/L), with a gradual decline in mature milk as lactation progresses, from 6-15 g/L in breast milk collected within one month of birth, to 4-6 g/L after 6 months. Significant differences in HMO composition have been described between countries. Different HMOs were shown to be predominant over the course of lactation, e.g., 3-fucosyllactose increased over lactation, whereas 2'-fucosyllactose decreased. Recent clinical studies on infant formula supplemented with 2'-fucosyllactose in combination with other oligosaccharides showed its limited beneficial effect on infant health.

The Implications of COVID-19 on Chinese Consumer Preferences for Lamb Meat.

This study assessed if Chinese consumer attitudes towards a range of lamb attributes (such as origin, food safety, appearance, taste, price), and their opinions of New Zealand lamb (9- and 7-point Likert scales, respectively), had changed since the outbreak COVID-19. The same survey was carried out in Shanghai and Beijing pre (December 2018) and post COVID-19 (November 2020), ~9 months after China's initial outbreak, with 500 and 523 consumers, respectively. From December 2018 to November 2020, there was an increase in the proportion of Chinese consumers purchasing red meat online or from a butcher, and cooking their lamb well-done. In contrast, there were minimal differences in Chinese consumer ratings between December 2018 and November 2020 for different lamb attributes and opinions of New Zealand lamb. Cluster analysis revealed that many consumers (140 in December 2018/376 in November 2020) used only a small portion of the high end of the scale when rating lamb attributes, resulting in little differences between the attributes. This study suggests COVID-19 has enhanced some food safety related behaviors but had little effect on Chinese opinions and preferences for New Zealand lamb attributes. It also highlights that survey design should be carefully considered when collecting responses from Chinese consumers.

Comparing Response of Sheep and Cow Milk on Acute Digestive Comfort and Lactose Malabsorption: A Randomized Controlled Trial in Female Dairy Avoiders.

Background: Sheep milk (SM) is a possible alternate dairy source for those who experience digestive symptoms with cow milk (CM). While both the milks contain lactose, one of the causes for self-reported intolerance to CM, the composition of SM and CM also differs across proteins and fats, which have been shown to impact digestive processes. Objective: To compare the acute digestive comfort and lactose malabsorption of SM to CM in female dairy avoiders. Method: In a double-blinded, randomized cross over trial, 30 dairy-avoiding females (aged 20-30 years) drank 650 mL of SM or CM (each reconstituted from spray dried powder) following an overnight fast, on two separate occasions at least 1 week apart. Blood samples were collected for glucose and insulin assessment, and single nucleotide polymorphisms of the lactase (LCT) gene (C/T13910 and G/A22018). Breath H2 and visual analog scale (VAS) digestive symptom scores were recorded at fasting and regular intervals over 4 h after ingestion. Results: Eighty percentage of study participants were lactase non-persistent (LNP; CC13910 and GG22018 genotype). Digestive symptoms, including abdominal cramps, distension, rumbling, bloating, belching, diarrhea, flatulence, vomiting, and nausea, were similar in response to SM and CM ingestion (milk × time, P > 0.05). Breath H2 was greater after CM than SM (72 ± 10 vs. 43 ± 6 ppm at 240 min, P < 0.001), which may be due to greater lactose content in CM (33 vs. 25 g). Accordingly, when corrected for the lactose content breath H2 did not differ between the two milks. The response remained similar when analyzed in the LNP subset alone (n = 20). Conclusions: Despite a higher energy and nutrient content, SM did not increase adverse digestive symptoms after ingestion, relative to CM, although there was a reduced breath H2 response, which could be attributed to the lower lactose content in SM. The tolerability of SM should be explored in populations without lactose intolerance for whom underlying trigger for intolerance is unknown.

Circulating Branched Chain Amino Acid Concentrations Are Higher in Dairy-Avoiding Females Following an Equal Volume of Sheep Milk Relative to Cow Milk: A Randomized Controlled Trial.

Background: Intolerances to bovine dairy are a motivating factor in consumers seeking alternate-or replacement-dairy beverages and foods. Sheep milk (SM) is an alternate dairy source, with greater protein, although similar amino acid composition compared to cow milk (CM). Studies are yet to address the appearance of circulating amino acids following consumption of SM, relative to CM, in humans. Objective: To clinically determine the appearance of branched chain amino acids, and other amino acids, in circulation in response to equal servings of SM and CM, in females who avoid dairy products. Design: In a double-blinded, randomized, cross-over trial, 30 self-described dairy avoiding females (20-40 years) drank 650 mL of SM or CM that were reconstituted from the spray dried powders (30 and 25 g in 180 mL water, respectively) on separate occasions, following an overnight fast. After reconstitution, the energy and protein provided by SM was higher than for CM (2,140 vs. 1,649 kJ; 29.9 vs. 19.4 g protein); content of branched chain amino acids (BCAAs) were 10.5 and 6.5 mg·mL-1, respectively. Blood samples were collected at fasting and at regular intervals over 5 h after milk consumption. Plasma amino acids were measured by HPLC. Results: 80% of subjects self-identified as lactose intolerant, and the majority (47%) "avoided drinking milk" "most of the time". SM resulted in greater plasma appearance of BCAAs at 60 min (641.1 ± 16.3 vs. 563.5 ± 14.4 µmol·L-1; p < 0.001) compared with CM. SM similarly resulted in elevated postprandial concentrations of the amino acids lysine, methionine, and proline, particularly at 240 min (time × milk interactions p = 0.011, 0.017, and p = 0.002, respectively). Postprandial increases in plasma alanine concentrations were sustained to 120 min after CM (time × milk interaction p = 0.001) but not after SM, despite greater quantities provided by SM. Conclusions: SM is a rich source of protein, and relative to CM, provides a greater quantity of BCAAs, with a corresponding elevation of the postprandial circulating BCAA response. SM is therefore a possible dairy alternative of benefit to those who need to increase total protein intake or for individuals with heightened protein requirements. Unique Identifier and Registry: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375324, identifier U1111-1209-7768.

Extensive bacteriocin gene shuffling in the Streptococcus bovis/Streptococcus equinus complex reveals gallocin D with activity against vancomycin resistant enterococci.

Streptococcus gallolyticus LL009 produces gallocin D, a narrow spectrum two component bacteriocin with potent activity against vancomycin-resistant enterococci. Gallocin D is distinct from gallocin A, a separate two component bacteriocin produced by S. gallolyticus. Although the gene clusters encoding gallocin A and gallocin D have a high degree of gene synteny, the structural genes are highly variable and appear to have undergone gene shuffling with other streptococcal species. Gallocin D was analysed in laboratory-based experiments. The mature peptides are 3,343 ± 1 Da and 3,019 ± 1 Da and could be readily synthesized and display activity against a vancomycin resistant Enterococcus strain EC300 with a MIC value of 1.56 µM. Importantly, these bacteriocins could contribute to the ability of S. gallolyticus to colonize the colon where they have been associated with colorectal cancer.

Structural characteristics of triacylglycerols contribute to the distinct in vitro gastric digestibility of sheep and cow milk fat prior to and after homogenisation.

The regiodistribution of fatty acids (FAs) in triacylglycerols (TAGs) is highly correlated to the digestion and absorption of dietary fats. During in vitro gastric digestion, medium-long-medium/short chain triacylglycerols (MLM) showed the fastest digestibility among 105 TAG molecular species, for both raw and homogenised milk, resulting from the higher activity of gastric lipase towards medium-chain fatty acids (MCFAs) than towards long-chain fatty acids (LCFAs). After 60 min of in vitro gastric digestion, the percentage of digestion of each MLM was 16.6-31.2% and 12.3-18.6% respectively in raw sheep and cow milk, and it reached 33.4-45.5% and 23.0-38.9% respectively, after homogenisation. Sheep milk TAGs were digested faster than cow milk TAGs in raw milk (16.1% and 12.4%, respectively) as well as after homogenisation (24.1% and 20.3%, respectively). This is due to the higher percentages of MCFAs esterified on the sn-1/3 positions of sheep milk TAGs (48.3-67.3% and 11.9-51.5% respectively for sheep and cow milk prior to and after homogenisation). Homogenisation favoured TAG lipolysis due to the increased fat globule surface area; however, it did not affect lipase regiospecificity towards TAG molecular species.

Differences in peptide generation following in vitro gastrointestinal digestion of yogurt and milk from cow, sheep and goat.

Fermentation of milk is commonly used throughout the world to produce a variety of foods with different health benefits. We hypothesised that due to differences in physicochemical properties and protein sequences among milk from different species and their fermented yogurt samples, their protein digestion and resulting peptide profiles would differ. Cow, goat and sheep milk and yogurt were compared at designated timepoints throughout in vitro gastric and intestinal digestion for differences in peptide profiles and peptide bioactivities. The results showed that most proteins in all milk and yogurt samples were digested within the early phase of gastric digestion. ß-Lg and ß-CN were digested faster in yogurt than milk, which was most evident for sheep products. Regardless of species, in vitro gastric and intestinal digestion released a higher concentration of specific peptides, particularly anti-hypertensives, from yogurt compared with their milk counterparts.

Factors affecting levels of volatile 4-alkyl branched-chain fatty acids in sheep milk from 2 contrasting farming systems in New Zealand.

Knowledge of factors influencing the levels of 4-alkyl branched-chain fatty acid (vBCFA), and consequently the "sheepy flavor" intensity of New Zealand sheep milk, is currently limited. In this study, we investigated the effects of 2 contrasting farming systems (fully housed/mid-lactation or pasture-grazed/late lactation) on the levels of vBCFA in sheep milk on a commercial farm in the North Island of New Zealand. Fully housed/mid-lactation ewes were housed 24 h/d and fed a total mixed ration. Pasture-grazed/late-lactation ewes were grazed 24 h/d and offered approximately 40% supplements because of poor pasture growth resulting from dry and hot climatic conditions. Any effects of genetics, age, lactation stage, feed composition, lambing date, or the environment in the housing barn or outdoors were confounded. The results obtained in this study were descriptive rather than definitive, because of the limitations of the experimental design. Levels of 4-methyloctanoic acid and 4-methylnonanoic acid in milk from fully housed/mid-lactation ewes increased during the trial period, but remained low in milk from pasture-grazed/late-lactation ewes. Levels of 4-ethyloctanoic acid in milk from the 2 groups of ewes were comparable throughout the trial. Increases in levels of 4-methyloctanoic acid and 4-methylnonanoic acid in sheep milk were associated with lactation stage and the proportion of lucerne silage fed to ewes. The level of free-form 4-ethyloctanoic acid was positively correlated with the proportion of soy meal in the diet and negatively correlated with the proportion of barley. Milk from fully housed/mid-lactation ewes had a higher flavor values than milk from pasture-grazed/late-lactation ewes because of its higher total amounts of vBCFA.

Human milk and infant formula differentially alters the microbiota composition and functional gene relative abundance in the small and large intestines in weanling rats.

PURPOSE: Human breast milk is the optimal source of nutrients for growing infants. However, many circumstances can arise which preclude breast milk feeding, leading to the use of infant formula, including during the weaning period. Many diet-related effects are modulated by the gut microbiome. Therefore, we investigated the effect of human milk (HM) or infant formula (IF) on the gut microbiota in weanling rats. METHODS: The gut microbiota of weanling male Sprague-Dawley rats fed HM or IF for 28 days was analysed by shotgun metagenome sequencing. Caecal contents were analysed by liquid chromatography-mass spectrometry metabolomics. RESULTS: Numerous genera within the Proteobacteria phylum were relatively more abundant in the ileum, caecum, and colon of rats fed HM, including ileal Escherichia (HM = 9.6% ± 4.3 SEM; IF = 0.9% ± 0.3 SEM; P = 0.03). Other taxa that differed between HM- and IF-fed rats included Prevotella and Ruminococcus. Overall, more differences were observed in the ileum than the caecum and colon between rats fed HM and IF. For the rats fed IF, in the ileum, the relative abundance of Bifidobacterium was higher (HM = 1.7% ± 0.7 SEM; IF = 5.0% ± 1.5 SEM; P = 0.04) with gene functions related to carbohydrate and amino acid metabolism also decreased. In the caecum, metabolic features such as bile acids were elevated while amino sugars were also decreased. CONCLUSION: Our results show that HM and IF composition differences are reflected in the gut microbiome composition and function in both the small and large intestines.

Structural-rheological characteristics of Chaplin E peptide at the air/water interface; a comparison with ß-lactoglobulin and ß-casein.

The Chaplin E peptide is a surface-active agent that can adsorb to the air/water interface and form interfacial films that display distinct interfacial properties as a function of pH. The ~2 nm thick homogeneous Chaplin E film formed under acidic conditions contains ordered structures that give a high dilatational elasticity. In contrast, the heterogeneous film formed under basic conditions contained fibrils resulting in a rough ~17 nm thick film with predominantly viscoelastic properties, probably due to the reduced intermolecular interactions. These fibrils were also susceptible to breakage, fragmenting into shorter fibrils, which gave a greater elasticity. The fibrils also lead to a greater shear viscosity compared to the ordered structures aligned within the Chaplin E film at pH 3.0. A higher stability was observed for the foam formed by the Chaplin E compared to the foam formed by ß-lactoglobulin, consistent with the greater rheological properties observed for the Chaplin E film at the interface. Our findings suggest that Chaplin E has potential to provide long time stability to dispersions in food, consumer goods or pharmaceutical applications, forming films with greater rheological properties and at least similar thickness to those formed by other surface-active proteins such as ß-casein and ß-lactoglobulin.

Comparison of the impact of bovine milk ß-casein variants on digestive comfort in females self-reporting dairy intolerance: a randomized controlled trial.

BACKGROUND: Lactose malabsorption (LM) is a major cause of digestive discomfort from dairy products. Recently, a role for bovine ß-casein A1 has been proposed. OBJECTIVES: We examined whether there are distinct symptoms of digestive discomfort due to either lactose or differing bovine ß-casein types. METHODS: Women (n = 40; age: 25.2 ± 0.5 y) with self-reported varying dairy tolerance underwent a 50-g lactose challenge. Based on postchallenge LM and digestive discomfort, participants were classified as either lactose intolerant (LI; n = 10, self-reported intolerant, diagnosed lactose intolerant), nonlactose dairy intolerant (NLDI; n = 20, self-reported intolerant, diagnosed lactose tolerant), or dairy tolerant (DT; n = 10, self-reported tolerant, diagnosed lactose tolerant). In a double-blinded randomized sequence, participants consumed 750 mL conventional milk (CON; containing A1 and A2 ß-casein and lactose), a2 Milk (A2M; exclusively containing A2 ß-casein with lactose), or lactose-free conventional milk (LF-CON; containing A1 and A2 ß-casein without lactose). Subjective digestive symptoms and breath hydrogen (measuring LM) were recorded regularly over 3 h, and further ad hoc digestive symptoms over 12 h. RESULTS: LI subjects experienced prolonged digestive discomfort with CON milk. A2M reduced (P < 0.05) some symptoms (nausea: A2M 8 ± 3 mm compared with CON 15 ± 3mm; fecal urgency: A2M 4 ± 1 compared with CON 10 ± 3 mm), and attenuated the rise in breath hydrogen over 3 h, relative to CON milk (A2M 59 ± 23 compared with CON 98 ± 25 ppm at 150 min; P < 0.01). In contrast, NLDI subjects experienced rapid-onset, transient symptoms (abdominal distension, bloating, and flatulence) without increased breath hydrogen, irrespective of milk type. CONCLUSIONS: In LI individuals, LM and digestive comfort with lactose-containing milks was improved with milk containing exclusively A2 ß-casein. Furthermore, self-reported dairy intolerance without LM (NLDI) is characterized by early-onset digestive discomfort following milk ingestion, irrespective of lactose content or ß-casein type. This trial was registered at www.anzctr.org.au as ACTRN12616001694404.