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1.
Food Funct ; 11(1): 358-369, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31799529

RESUMO

During heat processing of milk and dairy products, for example infant formula, the Maillard reaction occurs. In vitro and animal studies suggest that Maillard reaction induced lysine blockage impairs protein digestibility. Most studies that investigate the effect of glycation on protein digestion use a mixture of isolated milk protein with reducing sugars. In this study, infant formulas with 6.5%, 8.4%, 11.2%, 14.8%, 20.8%, and 44.5% of blocked lysine (BL) were digested in an in vitro infant digestion model and tested for protein hydrolysis and peptide release. OPA (o-phthalaldehyde) assay was used to assess the degree of protein hydrolysis. SDS-PAGE was conducted to monitor the hydrolysis of specific proteins. Peptides formed after gastric and intestinal digestion were identified by LC/MS. Protein hydrolysis of the 6.5% BL sample was significantly higher after 10 minutes of intestinal digestion compared to all other samples. Most differences were observed after intestinal digestion. A significant change in peptide patterns was observed for the 45% BL sample resulting in a relatively higher number of peptides with more than 14 amino acids. Mainly casein-derived peptides were affected. Overall, the average peptide length was significantly increased for the 44.5% BL glycated product (on average 10.2 amino acids for 6-21% BL vs. 11.4 amino acids for 45% BL; p < 0.001). In conclusion, glycation of milk proteins in an infant formula product can impair overall protein digestibility. These findings emphasize the importance of mild processing and having low BL levels in infant formula to ensure optimal digestion of proteins.

2.
Food Funct ; 10(12): 7818-7827, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31696193

RESUMO

Human milk provides a range of nutrients and bioactive components, which can support the growth and development of infants. However, human milk composition may change due to geographic and ethnic variation. This study investigated the variation of the Chinese human milk serum proteome based on mothers with different ethnicities living in different parts of China, using TMT labeling combined with Nano-LC Q Exactive HF MS/MS proteomics. In total, 693 proteins were identified and quantified in human milk serum from Yunnan (Han and Bai ethnicity), Gansu (Han and Tibetan ethnicity), Xinjiang (Uygur ethnicity), and Inner Mongolia (Mongolian ethnicity). The biological function distribution of identified proteins and the summed intensity of proteins belonging to each biological function were similar among groups. The five relatively highly abundant milk serum proteins, lactoferrin, serum albumin, polymeric immunoglobulin receptor, macrophage mannose receptor 1, and bile salt-activated lipase were not significantly different among different geographies and ethnicities. On the other hand, we found 34 proteins that did significantly differ with geography and ethnicity. Those significantly different proteins have known strong interaction in inflammation response and regulation of multi-organism processes. Taken together, biological function distribution was similar on both the qualitative and quantitative levels, and proteins with similar abundance are important in providing basic nutrition and protection for infants, whereas the significantly different proteins may be important for the healthy development of infants from different locations and ethnicities.

3.
Crit Rev Food Sci Nutr ; : 1-24, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31437019

RESUMO

Dairy is one of the main sources for high quality protein in the human diet. Processing may, however, cause denaturation, aggregation, and chemical modifications of its amino acids, which may impact protein quality. This systematic review covers the effect of milk protein modifications as a result of heating, on protein digestion and its physiological impact. A total of 5363 records were retrieved through the Scopus database of which a total of 102 were included. Although the degree of modification highly depends on the exact processing conditions, heating of milk proteins can modify several amino acids. In vitro and animal studies demonstrate that glycation decreases protein digestibility, and hinders amino acid availability, especially for lysine. Other chemical modifications, including oxidation, racemization, dephosphorylation and cross-linking, are less well studied, but may also impact protein digestion, which may result in decreased amino acid bioavailability and functionality. On the other hand, protein denaturation does not affect overall digestibility, but can facilitate gastric hydrolysis, especially of ß-lactoglobulin. Protein denaturation can also alter gastric emptying of the protein, consequently affecting digestive kinetics that can eventually result in different post-prandial plasma amino acid appearance. Apart from processing, the kinetics of protein digestion depend on the matrix in which the protein is heated. Altogether, protein modifications may be considered indicative for processing severity. Controlling dairy processing conditions can thus be a powerful way to preserve protein quality or to steer gastrointestinal digestion kinetics and subsequent release of amino acids. Related physiological consequences mainly point towards amino acid bioavailability and immunological consequences.

4.
Nutrients ; 11(6)2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31242665

RESUMO

The effect of glycation and aggregation of thermally processed ß-lactoglobulin (BLG) on binding to sRAGE and specific immunoglobulin E (sIgE) from cow milk allergic (CMA) patients were investigated. BLG was heated under dry conditions (water activity < 0.7) and wet conditions (in phosphate buffer at pH 7.4) at low temperature (<73 °C) and high temperatures (>90 °C) in the presence or absence of the milk sugar lactose. Nε-(carboxymethyl)-l-lysine (CML) western blot and glycation staining were used to directly identify glycation structures on the protein fractions on SDS-PAGE. Western blot was used to specify sRAGE and sIgE binding fractions. sRAGE binding was highest under wet-heated BLG independent of the presence of the milk sugar lactose. Under wet heating, high-molecular-weight aggregates were most potent and did not require the presence of CML to generate sRAGE binding ligands. In the dry system, sRAGE binding was observed only in the presence of lactose. sIgE binding affinity showed large individual differences and revealed four binding profiles. Dependent on the individual, sIgE binding decreased or increased by wet heating independent of the presence of lactose. Dry heating required the presence of lactose to show increased binding to aggregates in most individuals. This study highlights an important role of heating condition-dependent protein aggregation and glycation in changing the immunogenicity and antigenicity of cow's milk BLG.


Assuntos
Epitopos , Produtos Finais de Glicação Avançada/metabolismo , Temperatura Alta , Imunoglobulina E/metabolismo , Lactoglobulinas/metabolismo , Lisina/análogos & derivados , Hipersensibilidade a Leite/metabolismo , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Água/química , Produtos Finais de Glicação Avançada/imunologia , Imunoglobulina E/imunologia , Lactoglobulinas/imunologia , Lactose/química , Ligantes , Lisina/imunologia , Lisina/metabolismo , Hipersensibilidade a Leite/imunologia , Agregados Proteicos , Ligação Proteica , Conformação Proteica , Receptor para Produtos Finais de Glicação Avançada/imunologia
5.
Nutrients ; 11(3)2019 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-30818777

RESUMO

To better understand the variability of the type and level of serum proteins in human milk, the milk serum proteome of Chinese mothers during lactation was investigated using proteomic techniques and compared to the milk serum proteome of Dutch mothers. This showed that total milk serum protein concentrations in Chinese human milk decreased over a 20-week lactation period, although with variation between mothers in the rate of decrease. Variation was also found in the composition of serum proteins in both colostrum and mature milk, although immune-active proteins, enzymes, and transport proteins were the most abundant for all mothers. These three protein groups account for many of the 15 most abundant proteins, with these 15 proteins covering more than 95% of the total protein concentrations, in both the Chinese and Dutch milk serum proteome. The Dutch and Chinese milk serum proteome were also compared based on 166 common milk serum proteins, which showed that 22% of the 166 serum proteins differed in level. These differences were observed mainly in colostrum and concern several highly abundant proteins. This study also showed that protease inhibitors, which are highly correlated to immune-active proteins, are present in variable amounts in human milk and could be relevant during digestion.


Assuntos
Proteínas Sanguíneas/química , Lactação/fisiologia , Leite Humano/química , Proteínas Sanguíneas/metabolismo , China , Feminino , Humanos , Países Baixos
6.
J Agric Food Chem ; 64(33): 6477-86, 2016 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-27460534

RESUMO

Heating of protein- and sugar-containing materials is considered the primary factor affecting the formation of advanced glycation end products (AGEs). This study aimed to investigate the influence of heating conditions, digestion, and aggregation on the binding capacity of AGEs to the soluble AGE receptor (sRAGE). Samples consisting of mixtures of whey protein and lactose were heated at 130 °C. An in vitro infant digestion model was used to study the influence of heat treatment on the digestibility of whey proteins. The amount of sRAGE-binding ligands before and after digestion was measured by an ELISA-based sRAGE-binding assay. Water activity did not significantly affect the extent of digestibility of whey proteins dry heated at pH 5 (ranging from 3.3 ± 0.2 to 3.6 ± 0.1% for gastric digestion and from 53.5 ± 1.5 to 64.7 ± 1.1% for duodenal digestion), but there were differences in cleavage patterns of peptides among the samples heated at different pH values. Formation of sRAGE-binding ligands depended on the formation of aggregates and was limited in the samples heated at pH 5. Moreover, the sRAGE-binding activity of digested sample was changed by protease degradation and correlated with the digestibility of samples. In conclusion, generation of sRAGE-binding ligands during extensive heat treatment of whey protein/lactose mixtures is limited in acidic heating condition and dependent on glycation and aggregation.


Assuntos
Lactose/química , Receptor para Produtos Finais de Glicação Avançada/química , Proteínas do Soro do Leite/química , Cromatografia Líquida de Alta Pressão , Digestão , Glicosilação , Temperatura Alta , Concentração de Íons de Hidrogênio , Ligantes , Peptídeos/química
7.
Food Funct ; 7(1): 239-49, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26524422

RESUMO

Heat treatment is the most common way of milk processing, inducing structural changes as well as chemical modifications in milk proteins. These modifications influence the immune-reactivity and allergenicity of milk proteins. This study shows the influence of dry heating on the solubility, particle size, loss of accessible thiol and amino groups, degree of Maillard reaction, IgG-binding capacity and binding to the receptor for advanced glycation end products (RAGE) of thermally treated and glycated whey proteins. A mixture of whey proteins and lactose was dry heated at 130 °C up to 20 min to mimic the baking process in two different water activities, 0.23 to mimic the heating in the dry state and 0.59 for the semi-dry state. The dry heating was accompanied by a loss of soluble proteins and an increase in the size of dissolved aggregates. Most of the Maillard reaction sites were found to be located in the reported conformational epitope area on whey proteins. Therefore the structural changes, including exposure of the SH group, SH-SS exchange, covalent cross-links and the loss of available lysine, subsequently resulted in a decreased IgG-binding capacity (up to 33%). The binding of glycation products to RAGE increased with the heating time, which was correlated with the stage of the Maillard reaction and the decrease in the IgG-binding capacity. The RAGE-binding capacity was higher in samples with a lower water activity (0.23). These results indicate that the intensive dry heating of whey proteins as it occurs during baking may be of importance to the immunological properties of allergens in cow's milk, both due to chemical modifications of the allergens and formation of AGEs.


Assuntos
Temperatura Alta , Imunoglobulina G/química , Reação de Maillard , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Proteínas do Soro do Leite/química , Ligantes , Conformação Proteica
8.
J Dairy Sci ; 98(11): 7906-10, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26342985

RESUMO

Several parameters for improving volatile metabolite analysis using headspace gas chromatography-mass spectrometry (GC-MS) analysis of volatile metabolites were evaluated in the framework of identification of mastitis-causing pathogens. Previous research showed that the results of such volatile metabolites analysis were comparable with those based on bacteriological culturing. The aim of this study was to evaluate the effect of several method changes on the applicability and potential implementation of this method in practice. The use of a relatively polar column is advantageous, resulting in a faster and less complex chromatographic setup with a higher resolving power yielding higher-quality data. Before volatile metabolite analysis is applied, a minimum incubation of 8h is advised, as reducing incubation time leads to less reliable pathogen identification. Application of GC-MS remained favorable compared with regular gas chromatography. The complexity and cost of a GC-MS system are such that this limits the application of the method in practice for identification of mastitis-causing pathogens.


Assuntos
Escherichia coli/isolamento & purificação , Cromatografia Gasosa-Espectrometria de Massas/veterinária , Mastite Bovina/diagnóstico , Leite/química , Staphylococcus/isolamento & purificação , Animais , Bovinos , Cromatografia Gasosa , Escherichia coli/metabolismo , Feminino , Ionização de Chama/veterinária , Mastite Bovina/microbiologia , Staphylococcus/metabolismo , Compostos Orgânicos Voláteis/análise
9.
PLoS One ; 10(3): e0122234, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25798592

RESUMO

BACKGROUND: Breastfeeding has been linked to a reduction in the prevalence of allergy and asthma. However, studies on this relationship vary in outcome, which may partly be related to differences in breast milk composition. In particular breast milk composition may differ between allergic and non-allergic mothers. Important components that may be involved are breast milk proteins, as these are known to regulate immune development in the newborn. The objective of this study was therefore to explore differences in the proteins of breast milk from 20 allergic and non-allergic mothers. The results from this comparison may then be used to generate hypotheses on proteins associated with allergy in their offspring. METHODS: Milk samples from allergic and non-allergic mothers were obtained from the PIAMA project, a prospective birth cohort study on incidence, risk factors, and prevention of asthma and inhalant allergy. Non-targeted proteomics technology, based on liquid chromatography and mass spectrometry, was used to compare breast milk from allergic and non-allergic mothers. RESULTS: Nineteen proteins, out of a total of 364 proteins identified in both groups, differed significantly in concentration between the breast milk of allergic and non-allergic mothers. Protease inhibitors and apolipoproteins were present in much higher concentrations in breast milk of allergic than non-allergic mothers. These proteins have been suggested to be linked to allergy and asthma. CONCLUSIONS: The non-targeted milk proteomic analysis employed has provided new targets for future studies on the relation between breast milk composition and allergy.


Assuntos
Hipersensibilidade/metabolismo , Leite Humano/metabolismo , Proteoma , Proteômica , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Hipersensibilidade/imunologia , Lactente , Masculino , Pesquisa Qualitativa , Fatores de Risco
10.
J Nutr ; 145(3): 425-33, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25540406

RESUMO

BACKGROUND: Hundreds of naturally occurring milk peptides are present in term human milk. Preterm milk is produced before complete maturation of the mammary gland, which could change milk synthesis and secretion processes within the mammary gland, leading to differences in protein expression and enzymatic activity, thereby resulting in an altered peptide profile. OBJECTIVE: This study examined differences in peptides present between milk from women delivering at term and women delivering prematurely. METHODS: Nano-LC tandem mass spectrometry was employed to identify naturally occurring peptides and compare their abundances between term and preterm human milk samples at multiple time points over lactation. Term milk samples were collected from 8 mothers and preterm milk was collected from 14 mothers. The 28 preterm and 32 term human milk samples were divided into 4 groups based on day of collection (<14, 14-28, 29-41, and 42-58 d). RESULTS: Preterm milk peptide counts, ion abundance, and concentration were significantly higher in preterm milk than term milk. Bioinformatic analysis of the cleavage sites for peptides identified suggested that plasmin was more active in preterm milk than term milk and that cytosol aminopeptidase and carboxypeptidase B2 likely contribute to extensive milk protein breakdown. Many identified milk peptides in both term and preterm milk overlapped with known functional peptides, including antihypertensive, antimicrobial, and immunomodulatory peptides. CONCLUSION: The high protein degradation by endogenous proteases in preterm milk might attenuate problems because of the preterm infant's immature digestive system. This trial was registered at clinicaltrials.gov as NCT01817127.


Assuntos
Leite Humano/química , Peptídeos/metabolismo , Nascimento Prematuro , Nascimento a Termo , Cromatografia Líquida , Estudos de Avaliação como Assunto , Feminino , Voluntários Saudáveis , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Lactação , Proteínas do Leite/metabolismo , Estudos Prospectivos , Espectrometria de Massas em Tandem
11.
Food Res Int ; 63(Pt B): 203-209, 2014 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-25284962

RESUMO

Whey permeate is a co-product obtained when cheese whey is passed through an ultrafiltration membrane to concentrate whey proteins. Whey proteins are retained by the membrane, whereas the low-molecular weight compounds such as lactose, salts, oligosaccharides and peptides pass through the membrane yielding whey permeate. Research shows that bovine milk from healthy cows contains hundreds of naturally occurring peptides - many of which are homologous with known antimicrobial and immunomodulatory peptides - and nearly 50 oligosaccharide compositions (not including structural isomers). As these endogenous peptides and oligosaccharides have low-molecular weight and whey permeate is currently an under-utilized product stream of the dairy industry, we hypothesized that whey permeate may serve as an inexpensive source of naturally occurring functional peptides and oligosaccharides. Laboratory fractionation of endogenous peptides and oligosaccharides from bovine colostrum sweet whey was expanded to pilot-scale. The membrane fractionation methodology used was similar to the methods commonly used industrially to produce whey protein concentrate and whey permeate. Pilot-scale fractionation was compared to laboratory-scale fractionation with regard to the identified peptides and oligosaccharide compositions. Results were interpreted on the basis of whether industrial whey permeate could eventually serve as a source of functional peptides and oligosaccharides. The majority (96%) of peptide sequences and the majority (96%) of oligosaccharide compositions found in the laboratory-scale process were mirrored in the pilot-scale process. Moreover, the pilot-scale process recovered an additional 33 peptides and 1 oligosaccharide not identified from the laboratory-scale extraction. Both laboratory- and pilot-scale processes yielded peptides deriving primarily from the protein ß-casein. The similarity of the laboratory-and pilot-scale's resulting peptide and oligosaccharide profiles demonstrates that whey permeate can serve as an industrial-scale source of bovine milk peptides and oligosaccharides.

12.
Int J Food Microbiol ; 177: 29-36, 2014 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-24598513

RESUMO

Proto-cooperation between Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus is one of the key factors that determine the fermentation process and final quality of yoghurt. In this study, the interaction between different proteolytic strains of S. thermophilus and L. delbrueckii subsp. bulgaricus was investigated in terms of microbial growth, acidification and changes in the biochemical composition of milk during set-yoghurt fermentation. A complementary metabolomics approach was applied for global characterization of volatile and non-volatile polar metabolite profiles of yoghurt associated with proteolytic activity of the individual strains in the starter cultures. The results demonstrated that only non-proteolytic S. thermophilus (Prt-) strain performed proto-cooperation with L. delbrueckii subsp. bulgaricus. The proto-cooperation resulted in significant higher populations of the two species, faster milk acidification, significant abundance of aroma volatiles and non-volatile metabolites desirable for a good organoleptic quality of yoghurt. Headspace SPME-GC/MS and (1)H NMR resulted in the identification of 35 volatiles and 43 non-volatile polar metabolites, respectively. Furthermore, multivariate statistical analysis allows discriminating set-yoghurts fermented by different types of starter cultures according to their metabolite profiles. Our finding underlines that selection of suitable strain combinations in yoghurt starters is important for achieving the best technological performance regarding the quality of product.


Assuntos
Microbiologia de Alimentos , Lactobacillus delbrueckii/fisiologia , Leite/química , Streptococcus thermophilus/fisiologia , Iogurte/análise , Iogurte/microbiologia , Animais , Fermentação , Cromatografia Gasosa-Espectrometria de Massas , Concentração de Íons de Hidrogênio , Lactobacillus delbrueckii/crescimento & desenvolvimento , Lactobacillus delbrueckii/metabolismo , Espectroscopia de Ressonância Magnética , Metabolômica , Análise Multivariada , Streptococcus thermophilus/crescimento & desenvolvimento , Streptococcus thermophilus/metabolismo , Compostos Orgânicos Voláteis/análise , Iogurte/normas
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