In Vitro Assessment of the Impact of Industrial Processes on the Gastrointestinal Digestion of Milk Protein Matrices Using the INFOGEST Protocol (original) (raw)
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Journal of Food Research
Human digestion involves chemical, biochemical and fermentative processes integrated to achieve optimal nutrient absorption along the gastro-intestinal (GI) tract. In particular, efficient gastro-intestinal enzymatic digestion of proteins is critical for maximum upper intestinal protein absorption and may influence the distribution of dietary protein between the ‘host’ and microbiota. However, the relative efficiency of infant versus adult conditions of GI digestion of cow’s milk products have not been systematically studied. Conditions for in vitro GI enzymatic digestion, optimised for either infant or adult conditions, were applied to test pasteurised, skimmed milk, skimmed milk powder (SMP) and whey and casein protein fractions of cow’s milk. Research methods included digestion monitoring by o-phthaldialdehyde (OPA) derivitisation of peptides and free amino acids, and digestate analysis to characterise low mass ‘absorbing’ products (size exclus...
In vitro gastrointestinal digestion of liquid and semi-liquid dairy matrixes
LWT - Food Science and Technology, 2014
Protein digestion in two liquid dairy matrixes with different heat treatments (pasteurized and sterilized milks) and in one semi-liquid dairy matrix (stirred-yogurt) was investigated using an in vitro gastrointestinal digestion model. After buccal digestion, significantly lower amount of soluble proteins were measured in yogurt than in both milks. This difference between dairy matrixes decreased during gastric digestion and disappeared at the end of the duodenal digestion upon the proteolytic action of pepsin and pancreatin. Electrophoresis pattern of digested mixtures showed that casein digestion began at the gastric phase and was slower for pasteurized milk than sterilized milk and yogurt. At the end of duodenal digestion, no more intact caseins were present in all the dairy matrixes while faint bands of whey proteins were still visible for pasteurized milk and yogurt. The release of free amino acids during the duodenal phase varied according to their nature (acid, basic, neutral or hydrophobic) and seems to be governed by the specificity of the enzymes. These results suggest that the severity of milk's heat treatment influences the kinetics of protein digestion, mainly during the gastric phase, and that the impact of processing has to be considered to study protein digestion in dairy products.
Journal of Dairy Science, 2018
We investigated the effect of protein composition and, in particular, the presence of whey proteins or β-casein on the digestion behavior of a model infant formula using an in vivo piglet model. Three isocaloric diets optimized for piglets were prepared with the same concentrations of protein. For protein source, 1 diet contained only whey proteins and 2 contained a casein: whey protein ratio of 40:60 but differed in the amount of β-casein. To obtain the desired protein compositions, skim milk was microfiltered at 7 or 22°C, and retentates and permeates were combined with whey protein isolate. The diets were optimized to the nutritional needs of the piglets and fed to 24 newborn piglets for 18 d. Eight piglets were also fed ad libitum with sow milk and considered only as reference (not included in the statistical analysis). The study was carried out in 2 blocks, killing the animals 60 and 120 min after the last meal. All gastric contents, regardless of diet, showed a wide range of pH. Postprandial time did not affect the pH or physical properties of the gastric digesta. The digesta from whey protein-casein formulas showed significantly higher viscosity, a higher storage modulus, and a denser microstructure than digesta obtained from piglets fed whey protein formula. The β-casein: total casein ratio at the level used in this study did not significantly affect the physical and chemical properties of the stomach digestate. Although caseins showed extensive gastric hydrolysis, whey proteins remained largely intact at both postprandial times. The results indicate that the presence of different concentrations of milk proteins can be critical to the digestion properties of the food matrix and may affect the nutritional properties of the components.
In vitro digestion of bovine and caprine milk by human gastric and duodenal enzymes
International Dairy Journal, 2006
In vitro digestion was performed by human proteolytic enzymes on bovine and caprine individual milks. Two types of caprine milk were investigated: with high and low contents of a S1-casein (CN). In addition the influence of heating of the milk on digestion was examined. The digestion was performed in two steps using human gastric and duodenal juice. Protein and peptide profiles were studied by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF). Caprine milk proteins were digested faster than bovine milk proteins. This was confirmed by the degradation profile obtained for both cows' and goats' milk, and was most evident for b-lactoglobulin. Comparing the digestion of milk protein from two groups of goats, high and low in a S1-CN content, respectively, did not show significant differences. Heat treatment of milk had a strong and significant effect on the level of digestion. Raw milk was degraded faster than the heat-treated milk, and the effect of heating was different for bovine and caprine milk.
Trends in Food Science & Technology, 2004
Rather than using lengthy clinical studies, in vitro digestion of milk proteins by human neonatal gastric juice at pH values representing those in early neonatal life was investigated. Human milk proteins resisting digestion were immunoglobulins, secretory IgA, a S1-casein, secretory component, osteopontin and MUC-1. Bovine milk proteins resisting digestion at pH 4.0 were immunoglobulins, BSA, caseins, lactadherin, osteopontin, EPV20 and proteose peptone component 3 (PP3). Some proteins were rapidly digested e.g. CGMP. In vitro digestion provides rapid information regarding the susceptibility of proteins to gastric proteases and is a convenient alternative to clinical studies.
Food Hydrocolloids, 2013
There is an increasing interest in the development of functional foods and bioactive ingredients to fully exhaust food's potential to promote human health and prevent disease. The wish to rationally design such foods based on their gastrointestinal behavior has led to an upsurge in studies looking into the physicochemical basis of digestion and application of various in vitro methods. In light of advances in physiology and bioreactor technologies, this study aimed to develop and apply a dynamic yet simple in vitro method mirroring gastric pH alterations in the adult and infant stomach. These models were used to examine the digestive fate of b-lactoglobulin and lactoferrin as well as the behavior of their corresponding emulsions. In respect to proteolysis, SDS-PAGE of digesta collected revealed retarded protein breakdown and altered peptide profiles compared to common in vitro gastric models held at a constant pH. Regarding emulsion behavior, laser based droplet sizing and fluorescence microscopy showed altered times for emulsion destabilization, flocculation and coalescence occurring during the dynamic gastric digestions. Moreover, proteolysis and emulsion stability during digestion were found to differ between adults and infants. To the best of our understanding, the results of this study indicate that application of documented physiological gastric pH changes provides an opportunity to better understand the physicochemical basis of colloid digestion. Application of such models could help facilitate the development and screening of foods for health and well-being.
Impact of milk processing on the generation of peptides during digestion
International Dairy Journal, 2014
Milk processing may induce changes in dairy product composition and influence digestibility and nutrient bioavailability. Differences in protein degradation and peptide generation were studied for blactoglobulin and a S1-casein from commercially available dairy products before, during, and after in vitro digestion. All major milk proteins, except b-lactoglobulin, were degraded to smaller peptides during the gastric phase in all investigated products. After the gastric phase, a shortened fragment of b-lactoglobulin was identified in the non-fermented dairy products, underlining differences in protein conformation due to the fermentation process. During the gastric phase, greater numbers of small peptides were generated from a S1-casein than from b-lactoglobulin. The monitoring of generation of specific b-lactoglobulin and a S1-casein peptide profiles by liquid chromatographyemass spectrometry allowed the identification of potential bioactive peptides. Peptides with satiety-influencing DPP-4 inhibiting properties were monitored and quantities were compared between products to identify promising targets for the development of new health promoting products.
Dairy Science & Technology, 2010
The aim of this study was to compare the digestion of milk proteins from different species using an in vitro gastrointestinal model. Raw and heated milks from bovine, caprine, human and equine species were digested by human digestive enzymes. Digestion was performed in two 30-min sequential steps by digestive juices from the stomach (pH 2.5/37°C) and from the duodenum (pH 8.0/37°C). The degradation patterns of the milk proteins were visualized by SDS-PAGE and quantified using the ImageQuant program. Caseins in the equine milk were rapidly digested by the gastric juice in contrast to the caseins from the other species. During the subsequent digestion by the duodenal juice most of the caseins from all species were degraded within 5 min, and within 30 min only traces of caseins were detected. The mean casein micellar size varied between species in the range of 146.0-311.5 nm (equine > caprine > bovine > human). The α-lactalbumin from all species appeared to be very resistant to both gastric and duodenal digestions. A similar trend was shown for β-lactoglobulin from bovine and caprine milks, of which~60% intact protein remained, while only 25% remained intact in equine milk after total digestion. Equine milk contained a high amount of lysozyme, of which 60% remained intact in the present study. In heated milks from all species, only α-lactalbumin degradation increased approximately 12-20% in comparison to the raw milk. This study shows that equine milk with fast digestible proteins could be considered as a replacement for bovine milk in the diet of people with special needs, such as infants and the elderly. equine milk / bovine milk / caprine milk / human milk / digestion / whey protein / casein 摘要 -马奶、牛奶、山羊奶和人奶中酪蛋白和乳清蛋白在人胃肠道中消化性的比较○ 本研 究体外模拟了人胃肠道酶系对不同来源乳蛋白的消化性○ 对比了人胃肠道酶系对生鲜和热 处理的牛奶、山羊奶、马奶及人奶的消化能力○ 所有乳样品按照先后顺序分别在胃消化液 (pH 2.5/37°C) 和十二指肠液 (pH 8.0/37°C)
Protein digestion of different protein sources using the INFOGEST static digestion model
2020
In vitro digestion systems are valuable tools for understanding and monitoring the complex behavior of food degradation during digestion, thus proving to be good candidates for replacing in vivo assays. The aim of the present work was to study protein hydrolysis in a selection of different protein sources using the harmonized INFOGEST static protocol: three isolated proteins (collagen, zein, and whey protein) and five foods (sorghum flour, wheat bran cereals, peanuts, black beans, and pigeon peas). The proteins of all the substrates were analyzed by SDS-PAGE and HPLC-MS/MS. Individual amino acid composition was analyzed by high-performance liquid chromatography (HPLC). EAA/NEAA (essential amino acids/ nonessential amino acids) ratios in the substrates from low to high were as follows: wheat bran cereals, peanuts, collagen, zein, whey protein, sorghum, pigeon peas, and black beans. The results revealed sorghum, whey protein, and zein as good sources of BCAA. In all substrates, no intact protein from the substrates was visually detected by SDS-PAGE after the intestinal phase of in vitro digestion with the INFOGEST protocol. However, digestion-resistant peptides were detected in all substrates after the intestinal digestion phase. Protein hydrolysis was high in whey protein isolate and pigeon pea and low for wheat bran cereals and bovine collagen.