Digestion Of Milk Research Articles

Impact of human milk pasteurization on gastric digestion in preterm infants: a randomized controlled trial ,

Background: Holder pasteurization has been reported to modify human milk composition and structure by inactivating bile salt–stimulated lipase (BSSL) and partially denaturing some of its proteins, potentially affecting its subsequent digestion.Objective: We sought to determine the impact of human milk pasteurization on gastric digestion (particularly for proteins and lipids) in preterm infants who were fed their mothers’ own milk either raw or pasteurized.Design: In a randomized controlled trial, 12 hospitalized tube-fed preterm infants were their own control group in comparing the gastric digestion of raw human milk (RHM) with pasteurized human milk (PHM). Over a 6-d sequence, gastric aspirates were collected 2 times/d before and after RHM or PHM ingestion. The impact of milk pasteurization digestive kinetics and disintegration was tested with the use of a general linear mixed model.Results: Despite inactivating BSSL, instantaneous lipolysis was not affected by pasteurization (mean ± SD at 90 min: 12.6% ± 4.7%; P > 0.05). Lipolysis occurred in milk before digestion and was higher for PHM than for RHM (mean ± SD: 3.2% ± 0.6% and 2.2% ± 0.8%, respectively; P < 0.001). Pasteurization enhanced the proteolysis of lactoferrin (P < 0.01) and reduced that of α-lactalbumin (only at 90 min) (P < 0.05). Strong emulsion destabilization was observed, with smaller aggregates and a higher specific surface for PHM (P < 0.05). Pasteurization did not affect gastric emptying (∼30-min half time) or pH (mean ± SD: 4.4 ± 0.8) at 90 min.Conclusions: Overall, pasteurization had no impact on the gastric digestion of lipids and some proteins from human milk but did affect lactoferrin and α-lactalbumin proteolysis and emulsion disintegration. Freeze-thawing and pasteurization increased the milk lipolysis before digestion but did not affect gastric lipolysis. Possible consequences on intestinal digestion and associated nutritional outcomes were not considered in this study. This trial was registered at clinicaltrials.gov as NCT02112331.

Increasing Energy Ration of Bali Cattle to Improve Digestible Nutrient, Milk Yield and Milk Quality

To determine the effect of energy levels on digestible nutrient, milk production and milk quality of 7 months pregnant Bali cattle, was the purpose of this study. The study was conducted in Bali, Province of Indonesia on 12 pregnant breeding phase of pre-calving (2 months before the birth) with the parent body weight 329-340 kg/head. The treatment given is four types of Metabolizable Energy (ME) levels: 2000, 2100, 2200 and 2300/kg respectively as treatment A, B, C, and D. All ration contain 10% of crude protein. Variables measured: energy intake, digestible nutrient, milk yield, and milk quality. This research is a randomized block design. The results showed that increase energy ration until 2300 kcal ME/kg would significantly (P&lt;0.05) increase energy intake and highest at cattle consumed ratio D is 22239.55 kcal/day. However, digestible nutrient was not affected. Milk production increased with increasing energy rations and highest (P&lt;0.05) at cattle received treatment D is 2179.83 ml/day compared to treatment A 936.67 ml/day. Milk fat and milk lactose also highest (P&lt;0.05) in treatment D are 8.56% and 4.76% respectively. Based on these results, it can be concluded that increase energy ration will increase energy intake, milk yield and milk fat and milk lactose of Bali cattle.

Spinel-type manganese ferrite (MnFe2O4) microspheres: A novel affinity probe for selective and fast enrichment of phosphopeptides

The spinel-type magnetic manganese ferrite (MnFe2O4) microspheres synthesized by simple solvothermal method were used as a novel adsorbent for selective enrichment and effective isolation of phosphopeptides. The uniform MnFe2O4 magnetic affinity microspheres (MAMSs) had a narrow particle size distribution between 250 and 260nm, and displayed superparamagnetism with a saturation magnetization value of 67.0emu/g. Comprehensively, the possible formation mechanism of MnFe2O4 microspheres with ferric and manganous sources as dual precursors was elucidated by comparison with those of Fe3O4 nanoparticles and MnOOH nanosheets respectively with either ferric or manganous source as single precursor. It was suggested that the spherical or sheet nanostructures could be achieved via secondary recrystallization or Ostwald ripening. The MnFe2O4 MAMSs probe exhibited excellent dispersibility in aqueous solution, and rapid magnetic separation within 15s, as well as good reusability. More importantly, MnFe2O4 was highly selective for phosphopeptides because of the strong coordination interaction between metal ions (Fe3+ and Mn2+) and phosphate groups of phosphopeptdies. This high specificity was demonstrated by effectively enriching phosphopeptides from digest mixture of β-casein and bovine serum albumin (BSA) with high content of non-phosphopeptides, and embodied further in phosphopeptides enrichment from non-fat milk digests and human serum. Consequently, the prepared MnFe2O4 affinity materials are expected to possess great potential in phosphoproteome research.

Graft modification of cotton with phosphate group and its application to the enrichment of phosphopeptides

Grafting copolymerization, especially “grafting from” approach, has attracted a great attention for the preparation of cellulose-based materials with various functionalities. In this study, a novel phosphate group-containing cotton fiber-based material, CF-NH2-AZO-p(VPA-x), was successfully synthesized by a “grafting from” radical polymerization approach using vinyl phosphonic acid (VPA) as monomer. The phosphate group content of CF-NH2-AZO-p(VPA-x) could be easily regulated by adjusting the concentration of VPA monomer. Subsequently, titanium ions immobilized CF-NH2-AZO-p(VPA-x) (CF-NH2-AZO-p(VPA-x)-Ti4+) was prepared and used as an immobilized metal affinity chromatography (IMAC) adsorbent for the selective enrichment of phosphopeptides from various biological samples. The relationship between enrichment efficiency and phosphate group content of CF-NH2-AZO-p(VPA-x)-Ti4+ was investigated. The optimized CF-NH2-AZO-p(VPA-2)-Ti4+ (x=2) exhibited high selectivity and extraction capacity in phosphopeptides enrichment from standard peptides mixture, non-fat milk digests and protein-rich human serum. In addition, CF-NH2-AZO-p(VPA-2)-Ti4+ was further applied for the specific capture of phosphopeptides from tryptic digests of rat brain lysate, and 3241 unique phosphopeptides were identified from 0.5mg of rat brain by combining CF-NH2-AZO-p(VPA-2)-Ti4+ pretreatment with liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis. We expect the proposed method can promote the development of “grafting from” approach in the preparation of cellulose-based adsorbents and broaden the application of cellulose-based adsorbents for biological analysis.

Milk Yield and Composition and Pasture Ruminal Digestion in Grazing Dairy Cows Receiving Three Levels of Energy Concentrate Supplementation

The objective of the experiment was to determine the effect of feeding three levels (T3.5, T7.0 and T10.5) of energy concentrate (3.5, 7.0 and 10.5 kg cow-1 day-1) on total dry matter (DM) and energy intakes, milk yield and composition, nutritional value of milk and rumen pasture neutral detergent fiber (NDF) digestion in grazing dairy cows. Twenty-one multiparous Holstein cows in early lactation (70.2 ± 13 days postpartum) producing 37.1 (±4.7) kg of milk were assigned to a 3 treatments (7 cows/treatment) × 3 periods Latin square design. Parameters of ruminal environment and pasture NDF degradation were obtained using 3 additional cows of the same breed fitted with rumen cannulae. On a wet basis, concentrate was composed by corn grain (68%), soybean meal (22%), wheat bran (8%) and a vitamin-mineral nucleus with monensin. Pasture (Medicago sativa, sp) was used in a rotational grazing system with an herbage allowance of 30 kg DM cow-1 d-1. Yield (kg cow-1 d-1) of fat corrected milk (4% FCM) resulted higher (p p p p p p p p

Assessment of IgE Reactivity of β-Casein by Western Blotting After Digestion with Simulated Gastric Fluid.

Cow's milk allergy is defined as an immunologically mediated adverse reaction to cow's milk proteins and it is usually, along with hen's egg allergy, the first food allergy identified in childhood.One of the main aspects to consider when evaluating the allergenic potential of food proteins is the effect of gastric digestion. It is known that allergens are usually able to survive the harsh acidic environment of the stomach, tolerate the presence of surfactants, and resist digestion by pepsin. They might also be digested into high molecular weight peptide fragments, which retain the same, or sometimes increased, IgE-binding. In this respect, western blotting is a highly sensitive and efficient technique that we have used to detect IgE-binding to the digests of milk and egg proteins. Given the importance of the resistance of food proteins to gastric digestion in their capacity to modulate the immune response, we describe in this chapter the assessment of IgE reactivity of a relevant cow's milk allergen, β-casein, by western blotting after simulated digestion under relevant physiological conditions.

Enzymes in Human Milk.

Milk proteins are a complex and diverse source of biological activities. Beyond their function, intact milk proteins also act as carriers of encrypted functional sequences that, when released as peptides, exert biological functions, including antimicrobial and immunomodulatory activity, which could contribute to the infant's competitive success. Research has now revealed that the release of these functional peptides begins within the mammary gland itself. A complex array of proteases produced in mother's milk has been shown to be active in the milk, releasing these peptides. Moreover, our recent research demonstrates that these milk proteases continue to digest milk proteins within the infant's stomach, possibly even to a larger extent than the infant's own proteases. As the neonate has relatively low digestive capacity, the activity of milk proteases in the infant may provide important assistance to digesting milk proteins. The coordinated release of these encrypted sequences is accomplished by selective proteolytic action provided by an array of native milk proteases and infant-produced enzymes. The task for scientists is now to discover the selective advantages of this protein-protease-based peptide release system.

Highly selective enrichment of phosphopeptides using Zr4+-immobilized Titania nanoparticles

It is urgent to selectively enrich trace phosphorylated proteins or peptides from complex biological sample for mass spectrometry (MS)-based phosphoproteomics. In this study, a novel immobilized metal affinity chromatography (IMAC) material with DOTA(1,4,7,10-tetraazacyclododecane N, N′, N′′, N′′′-tetra-acetic acid) coated on the surface of TiO2 nanomaterials and functionalized with the metal ion Zr4+(TiO2@DOTA-Zr) has been synthesized successfully to improve the enrichment specificity and sensitivity for phosphopeptides. TiO2 nanomaterials were chosen as a support matrix, which will offer a high specific surface area to enhance the amounts of immobilized Zr4+ ions and will provide an additional selectivity for the special enrichment of phosphopeptides. Also, the introduction of DOTA will endow a stronger binding interaction between the Zr4+ ion and DOTA to reduce the loss of the metal ion Zr4+ during sample loading and washing steps. The novel TiO2@DOTA-Zr nanohybrids exhibited higher sensitivity and selectivity for phosphopeptides from the standard protein digests, the tryptic digests of nonfat milk and human serum, showing a great selective enrichment capability toward the complicated biological samples.

Synthesis of Polyethylenimine Functionalized Mesoporous Silica for In-Pipet-Tip Phosphopeptide Enrichment.

Synthesis of functionalized mesoporous silica material with large particle size remains a chanllenge. In this work, polyethylenimine (PEI) functionalized mesoporous silica (PFMS) with particle size as large as 100 μm was successfully synthesized by a facile method. In the synthesis process, PEI served as four roles simultaneously, including functionalized reagent, alkaline catalyst, template for particle formation, and pore-structure-directing agent. The surface areas of the products were higher than 260 m2/g. Benefiting from the large particle size and high surface area, PFMS was packed in a pipet tip to fabricate a convenient and miniaturized solid phase extraction apparatus for sample preparation. Additionally, based on the extremely abundant basic sites in the organic units of PFMS, the in-pipet-tip system was used as an anion-exchanger for phosphopeptide enrichment. The specificity of the developed method was investigated by capture of phosphopeptides from tryptic digests of standard protein mixtures, tryptic digests of nonfat milk, and human serum. Furthermore, the method was utilized to analyze phosphopeptides in tryptic digests of rat brain lysate, and 2251 unique phosphopeptides were successfully detected.

Effect of homogenization and heat treatment on the behavior of protein and fat globules during gastric digestion of milk

The effects of homogenization and heat treatment on the formation and the breakdown of clots during gastric digestion of whole milk were investigated using a human gastric simulator. Homogenization and heat treatment led to formation of coagula with fragmented and crumbled structures compared with the coagulum formed from raw whole milk, but a larger fraction of the protein and more fat globules were incorporated into the coagula induced by action of the milk-clotting enzyme pepsin. The fat globules in the whole milk appeared to be embedded in the clots as they formed. After formation of the clot, the greater numbers of pores in the structures of the clots formed with homogenized milk and heated whole milk led to greater rates of protein hydrolysis by pepsin, which resulted in faster release of fat globules from the clots into the digesta. Coalescence of fat globules occurred both in the digesta and within the protein clots no matter whether they were in homogenized or heated milk samples. The formation of clots with different structures and hence the changes in the rates of protein hydrolysis and the release of milk fat into the digesta in the stomach provide important information for understanding the gastric emptying of milk and the potential to use this knowledge to manipulate the bioavailability of fat and other fat-soluble nutrients in dairy products.

Effects of Genetically Modified Milk Containing Human Beta-Defensin-3 on Gastrointestinal Health of Mice.

This study was performed to investigate the effects of genetically modified (GM) milk containing human beta-defensin-3 (HBD3) on mice by a 90-day feeding study. The examined parameters included the digestibility of GM milk, general physical examination, gastric emptying function, intestinal permeability, intestinal microflora composition of mice, and the possibility of horizontal gene transfer (HGT). The emphasis was placed on the effects on gastrointestinal (GI) tract due to the fact that GI tract was the first site contacting with food and played crucial roles in metabolic reactions, nutrition absorption and immunity regulation in the host. However, the traditional methods for analyzing the potential toxicological risk of GM product pay little attention on GI health. In this study, the results showed GM milk was easy to be digested in simulated gastric fluid, and it did not have adverse effects on general and GI health compared to conventional milk. And there is little possibility of HGT. This study may enrich the safety assessment of GM product on GI health.

Rheological properties of lactose-free dairy desserts.

People suffering from lactose intolerance cannot digest milk or lactose-containing foods. Lactose-free diet is essential for them since they do not have the ability to produce lactase to breakdown milk sugar. Physical properties of lactose-free dairy desserts will most probably be different than that of lactose containing ones because of lactose hydrolysis. In this study, it was aimed to analyze the rheological and textural behaviors of different lactose-free dessert formulations containing different gum types and different waxy maize starch and sucrose concentrations. Waxy maize starch was used at concentrations of 0.032 g·mL-1, 0.040 g·mL-1, and 0.048 g·mL-1 In addition to waxy maize starch, guar gum, gum arabic, or κ-carrageenan at two different concentrations (1.0% w/w and 0.5% w/w) was added. Sucrose was added at concentrations of 0.14 g·mL-1 and 0.10 g·mL-1 in lactose-free desserts. Power law model was found to be suitable to explain the flow behavior of desserts. The storage and loss modulus of lactose-free desserts were higher than that of lactose-containing desserts. The κ-Carrageenan was found to be the most effective gum for structure build-up.

Soy milk digestion extract inhibits progression of prostate cancer cell growth via regulation of prostate cancer‑specific antigen and cell cycle-regulatory genes in human LNCaP cancer cells.

Soy milk, which is produced from whole soybeans, contains a variety of biologically active components. Isoflavones are a class of soy-derived phytoestrogens with beneficial effects, among which genistein (GEN) has been previously indicated to reduce the risk of prostate cancer. The present study evaluated the effects of soy milk digestion extract (SMD) on the progression of prostate cancer via the estrogen receptor (ER)β in human LNCaP prostate cancer cells. To evaluate the effects of SMD (daizein, 1.988 mg/100g, glycitein, 23.537mg/100g and GEN, 0.685mg/100g) on cell proliferation, LNCaP cells were cultured in media containing vehicle (0.1% dimethyl sulfoxide), 17β‑estradiol (E2; 2.7x10‑7mg/ml), GEN (2.7x10-2mg/ml) of SMD (total aglycon concentration, 0.79mg/ml), after which the cell viability was examined using an MTT assay. The cell viability was significantly elevated by E2 (by 45±0.18%), while it was markedly reduced by GEN (73.2±0.03%) or SMD (74.8±0.09%). Semi‑quantitative reverse transcription polymerase chain reaction analysis was performed to assess the mRNA expression levels of target genes, including ERβ, prostate cancer‑specific antigen (PSA) and cell cycle regulators p21, CyclinD1 and cyclin-dependent kinase (CDK)4. The expression of ERβ was almost completely diminished by E2, whereas it was significantly elevated by SMD. In addition, the expression levels of PSA were considerably reduced by SMD. The expression of p21 was significantly elevated by SMD, while it was markedly reduced by E2. Of note, the expression levels of CyclinD1 and CDK4 were considerably elevated by E2, while being significantly reduced by GEN and SMD. All of these results indicated that SMD may inhibit the proliferation of human prostate cancer cells via regulating the expression of ERβ, PSA, p21, CyclinD1 and CDK4 in an ER-dependent manner.

Composition and properties of peptides that survive standardised in vitro gastro-pancreatic digestion of bovine milk

There are conflicting results on the release and conservation of bioactive protein sequences during in vitro digestion. Only the peptides that are released and survive may exert their action. Peptides <3 kDa were determined by mass spectrometry after standardised in vitro gastro-pancreatic digestion of bovine milk. At a degree of digestion of 30.7%, 384 peptides were obtained from 2 to 25 residues in length. Five other peptides were recovered after reduction of disulphide bonds. Due to the presence of proline residues at the last or second last position at the C-terminus, a high number of peptides with ACE-inhibitory activity were obtained. Peptides with opioid, antimicrobial, immunomodulatory and antithrombotic activities were recovered, with many precursors and degradative products. Peptides with opioid and antimicrobial activities may be the result of evolutionary processes. The peptides obtained were similar to those released in the human jejunum.

Ultrasonography to investigate the effect of supplementing whole milk with complex carbohydrates and specific amino acids on curd retention in the abomasum of dairy calves

AIM: To determine whether the retention time of curd in the abomasum of calves was influenced by supplementing milk with a plant-derived carbohydrate and amino acid supplement, evaluated non-invasively using ultrasonography.METHODS: Female dairy calves aged between 2–6 days of age were sourced from a commercial farm in March 2013. All calves were fed whole milk until weaning (4 L per day); 21 calves were supplemented with a probiotic until 18 days of age, and thereafter with a plant-derived complex carbohydrate and amino acid supplement until weaning, and 22 calves were just fed whole milk. Treatment groups were balanced for age, weight and breed. At 9–14, 24–29 and 52–57 days of age, the abomasum of each calf was examined using ultrasonography immediately before and after feeding, 1 and 2 hours after feeding, and then at 30 minute intervals until curd was no longer visible in the abomasum. Abomasal volume and curd size were recorded to assess retention time of curd in the abomasum.RESULTS: At 9–14 days of age, mean retention time of curd in the abomasum was similar (4.6 hours) in both groups. At 24–29 days of age, when the supplemented calves had been receiving the supplement for approximately 10 days, mean curd retention time was longer by 1.4 (SE 0.28) hours in supplemented compared with unsupplemented calves (p<0.001). At 52–57 days of age, mean retention time was longer by 0.7 (SE 0.34) hours compared to unsupplemented calves (p=0.05).CONCLUSION: Using ultrasonography, changes in abomasal content could be followed non-invasively over time and it was demonstrated that the plant-derived complex carbohydrate supplement increased the curd retention time in the abomasum. We speculate that the increased retention time enables an increased availability of nutrients following a more complete digestion of milk, thereby improving animal performance.

Impact of human milk pasteurization on the kinetics of peptide release during in vitro dynamic term newborn digestion.

Holder pasteurization (62.5°C, 30 min) ensures sanitary quality of donor's human milk but also denatures beneficial proteins. Understanding whether this further impacts the kinetics of peptide release during gastrointestinal digestion of human milk was the aim of the present paper. Mature raw (RHM) or pasteurized (PHM) human milk were digested (RHM, n = 2; PHM, n = 3) by an in vitro dynamic system (term stage). Label-free quantitative peptidomics was performed on milk and digesta (ten time points). Ascending hierarchical clustering was conducted on "Pasteurization × Digestion time" interaction coefficients. Preproteolysis occurred in human milk (159 unique peptides; RHM: 91, PHM: 151), mostly on β-casein (88% of the endogenous peptides). The predicted cleavage number increased with pasteurization, potentially through plasmin activation (plasmin cleavages: RHM, 53; PHM, 76). During digestion, eight clusters resumed 1054 peptides from RHM and PHM, originating for 49% of them from β-casein. For seven clusters (57% of peptides), the kinetics of peptide release differed between RHM and PHM. The parent protein was significantly linked to the clustering (p-value = 1.4 E-09), with β-casein and lactoferrin associated to clusters in an opposite manner. Pasteurization impacted selectively gastric and intestinal kinetics of peptide release in term newborns, which may have further nutritional consequences.

Impact of pasteurization of human milk on preterm newborn in vitro digestion: Gastrointestinal disintegration, lipolysis and proteolysis

Human milk feeding is an important recommendation for preterm newborns considering their vulnerability and digestive immaturity. Holder pasteurization (62.5°C, 30min) applied in milk banks modifies its biological quality and its microstructure. We investigated the impact of pasteurization of preterm human milk on its gastrointestinal kinetics of lipolysis, proteolysis and structural disintegration. An in vitro dynamic system was set up to simulate the gastrointestinal digestion of preterm newborns. A pool of preterm human milk was digested as raw or after Holder pasteurization. Pasteurization impacted the microstructure of undigested human milk, its gastrointestinal disintegration and tended to limit the intestinal lipolysis. Furthermore, the gastrointestinal bioaccessibility of some fatty acids was decreased by pasteurization, while the intestinal bioaccessibility of some amino acids was selectively modulated. The impact of pasteurization on the digestion of human milk may have nutritional relevance in vivo and potentially modulates preterm development and growth.

Effect of heat and homogenization on in vitro digestion of milk

Central to commercial fluid milk processing is the use of high temperature, short time (HTST) pasteurization to ensure the safety and quality of milk, and homogenization to prevent creaming of fat-containing milk. Ultra-high-temperature sterilization is also applied to milk and is typically used to extend the shelf life of refrigerated, specialty milk products or to provide shelf-stable milk. The structures of the milk proteins and lipids are affected by processing but little information is available on the effects of the individual processes or sequences of processes on digestibility. In this study, raw whole milk was subjected to homogenization, HTST pasteurization, and homogenization followed by HTST or UHT processing. Raw skim milk was subjected to the same heating regimens. In vitro gastrointestinal digestion using a fasting model was then used to detect the processing-induced changes in the proteins and lipids. Using sodium dodecyl sulfate-PAGE, gastric pepsin digestion of the milk samples showed rapid elimination of the casein and α-lactalbumin bands, persistence of the β-lactoglobulin bands, and appearance of casein and whey peptide bands. The bands for β-lactoglobulin were eliminated within the first 15min of intestinal pancreatin digestion. The remaining proteins and peptides of raw, HTST, and UHT skim samples were digested rapidly within the first 15min of intestinal digestion, but intestinal digestion of raw and HTST pasteurized whole milk showed some persistence of the peptides throughout digestion. The availability of more lipid droplets upon homogenization, with greater surface area available for interaction with the peptides, led to persistence of the smaller peptide bands and thus slower intestinal digestion when followed by HTST pasteurization but not by UHT processing, in which the denatured proteins may be more accessible to the digestive enzymes. Homogenization and heat processing also affected the ζ-potential and free fatty acid release during intestinal digestion. Stearic and oleic acids were broken down faster than other fatty acids due to their positions on the outside of the triglyceride molecule. Five different casein phosphopeptide sequences were observed after gastric digestion, and 31 sequences were found after intestinal digestion, with activities yet to be explored. Processing affects milk structure and thus digestion and is an important factor to consider in design of foods that affect health and nutrition.

Intake, apparent digestibility, production, and composition of milk from cows fed diets with different sources of lipids

The objective of this study was to evaluate the effect of different sources of lipids in the diets of dairy cows on the intake and digestibility of nutritional fractions, and milk production and composition. The experiment was conducted in a 42-hectare area divided into eight paddocks covered with Brachiaria brizantha. Twelve crossbred Holstein × Zebu cows were distributed into three simultaneous 4 × 4 Latin squares. The treatments consisted of different sources of lipids, as follows: diet with no extra source of lipids; diet with cottonseed as the source of lipids; diet with soy oil; and diet with used frying soy oil. The intakes of dry matter, neutral detergent fiber, crude protein, total carbohydrates, and non-fibrous carbohydrates were similar for all diets. The use of lipid sources caused a decrease in the apparent digestibility of dry matter, neutral detergent fiber, non-fibrous carbohydrates, and crude protein. The levels of protein, lactose, and defatted dry matter were reduced with the use of lipid sources but did not affect milk production. The use of cottonseed, soy oil, and used frying soy oil as sources of lipids in diets for lactating cows at pasture do not improve milk production, and their use is therefore optional.

Release of angiotensin converting enzyme-inhibitory peptides during in vitro gastro-intestinal digestion of camel milk

Angiotensin-converting enzyme (ACE)-inhibitory peptides released from camel milk after simulated gastro-intestinal digestion were identified. The hydrolysis degree increased during digestion. The highest ACE-inhibitory activity was found in the post-pancreatic <3 kDa fraction. Peptides responsible for the biological activity were isolated by reversed-phase high-performance liquid chromatography and identified by mass spectrometry. Among the identified sequences, 17 were identical to known bioactive peptides with ACE-inhibitory activity. Based on previous structure–activity relationship studies, the sequence of some peptides allowed us to anticipate the presence of biological activities. The anti-hypertensive tripeptide isoleucine-proline-proline (IPP) was identified and quantified in digested camel milk. The amount of released IPP was 2.56 ± 0.15 mg L−1 of milk. For the first time, we showed that IPP is released during the gastro-intestinal digestion of camel milk κ-casein. This research provides the basis to increase the exploitation of the health benefits of camel milk.