Peptide Release after Simulated Infant In Vitro Digestion of Dry Heated Cow's Milk Protein and Transport of Potentially Immunoreactive Peptides across the Caco-2 Cell Monolayer

Effects of dry heating on the cleavage of casein and whey protein into peptides under simulated infant digestion

Glycation elicits diverse effects on the digestion of caseins and whey proteins in a goat protein model system (40 % casein,60 % whey proteins). Caseins generated longer peptides in the digesta of heated vs unheated samples. The further cleavage of casein peptides was hindered by dry heating, which might be induced by glycated modification. This reduced cleavage of casein peptides may also explain the decreased intensity of casein-derived bioactive peptides. Moreover, dry heating for 72 h significantly decreased the total intensity and number of whey protein-derived peptides. Whey protein-derived peptides in heated samples were shorter than those in unheated samples, and the cleavage sites of whey proteins were notably influenced. Dry heating increased the intensity of whey protein-derived bioactive peptides. These changes also affected the predicted bioactivity of peptides in the digesta, which may influence infant health. This study offers insights into the infant digestion of milk proteins into peptides.

Transcriptome and metabolome analyses reveal the effects of formula and breast milk on the growth and development of human small intestinal organoids

Breast milk is widely acknowledged as the ideal nutritional resource for infants and can well meet the nutritional requirements for baby's growth and development. Infant formula is a substitute for breast milk, designed to closely mimic its composition and function for breast milk. Most of the previous studies used tumor colorectal cancer cell lines to study the nutritional potency of formula and its components, so realistic data closer to the baby could not be obtained. Small intestinal organoids, derived from differentiated human embryonic stem cells, can be used to simulate nutrient absorption and metabolism in vitro. In this experiment, we used small intestinal organoids to compare the nutrient absorption and metabolism of three infant formulae for 0-6 months with breast milk samples. Transcriptome and metabolome sequencing methods were used to analyze the differentially expressed genes (DEGs) and differentially expressed metabolites (DEMs). The pathways related to DEGs, DEMs were enriched using GO, KEGG, GSEA and other methods to investigate their biological characteristics. We have found that both formula and breast milk promote the development of the infant's immune system, nutrient absorption and intestinal development. In PMH1 we found that the addition of oligofructose to milk powder promoted lipid metabolism and absorption. In PMH2 we found that whey protein powder favours the development of the immune system in infants. In PMH3 we found that oligogalactans may act on the brain-gut axis by regulating the intestinal flora, thereby promoting axon formation and neural development. By linking these biological properties of the milk powder with its composition, we confirmed the effects of added ingredients on the growth and development of infants. Also, we demonstrated the validity of small intestine organoids as a model for absorption and digestion in vitro. Through the above analyses, the advantages and disadvantages of the roles of formula and breast milk in the growth and metabolism of infants were also compared.

Coupling in vitro food digestion with in vitro epithelial absorption; recommendations for biocompatibility

As food transits the gastrointestinal tract, food structures are disrupted and nutrients are absorbed across the gut barrier. In the past decade, great efforts have focused on the creation of a consensus gastrointestinal digestion protocol (i.e., INFOGEST method) to mimic digestion in the upper gut. However, to better determine the fate of food components, it is also critical to mimic food absorption in vitro. This is usually performed by treating polarized epithelial cells (i.e., differentiated Caco-2 monolayers) with food digesta. This food digesta contains digestive enzymes and bile salts, and if following the INFOGEST protocol, at concentrations that although physiologically relevant are harmful to cells. The lack of a harmonized protocol on how to prepare the food digesta samples for downstream Caco-2 studies creates challenges in comparing inter laboratory results. This article aims to critically review the current detoxification practices, highlight potential routes and their limitations, and recommend common approaches to ensure food digesta is biocompatible with Caco-2 monolayers. Our ultimate aim is to agree a harmonized consensus protocol or framework for in vitro studies focused on the absorption of food components across the intestinal barrier.

Differential effects of heating modes on the immunogenic potential of soy-derived peptides released after in vitro infant digestion

During production of soy-based infant formula, soy protein undergoes heating processes. This study investigated the differential impact of heating modes on the immunogenic potential of peptides in soy protein digests. Wet or dry heating was applied, followed by in vitro gastrointestinal infant digestion. The released peptides were analyzed by LC-MS/MS. Bioinformatics tools were utilized to predict and identify potential linear B-cell and T-cell epitopes, as well as to explore cross-reactivity with other legumes. Subsequently, the peptide intensities of the same potential epitope across different experimental conditions were compared. As a result, we confirmed the previously observed enhancing effect of wet heating on infant digestion and inhibitory effect of dry heating. A total of 8,546 peptides were detected in the digests, and 6,684 peptides were with a score over 80. Among them, 29 potential T-cell epitopes and 27 potential B-cell epitopes were predicted. Cross-reactivity between soy and other legumes, including peanut, pea, chickpea, lentil, kidney bean, and lupine, was also detected. Overall, heating and digestion time could modulate the potential to trigger peptide-induced immune responses.

Traditional cooking methods decreased the allergenicity of egg proteins

Egg allergy is one of the most common food allergies globally. This study aimed to assess the impact of four traditional cooking methods on the allergenicity of egg proteins using a comprehensive strategy, including simulated gastrointestinal digestion in vitro, serology experiments, a rat basophilic leukemia (RBL)-2H3 cell degranulation model, and a passive cutaneous anaphylaxis (PCA) mice model, and the structure changes were detected by circular dichroism (CD) spectra and ultraviolet (UV) spectra. The results showed that the processed egg proteins were more readily digested compared to raw egg proteins. The serological experiments revealed a significant reduction in immunoglobulin E binding of egg proteins after thermal treatments (p < 0.05), particularly after frying. Subsequently, the RBL-2H3 cell degranulation experiment demonstrated a marked decrease in the level of egg allergens-induced β-hexosaminidase release after cooking (p < 0.05). Moreover, the results from the PCA mice model indicated that the increase in vascular permeability was effectively relieved in the treated groups, especially in frying group (p < 0.05). Additionally, the α-helix and β-turn contents of processed egg proteins were significantly decreased (p < 0.05) compared with native egg proteins. The UV spectra findings showed that all cooking treatments caused significant alterations in the tertiary structure, and fluorescence analysis indicated that cooking decreased the surface hydrophobicity of egg proteins. In conclusion, four traditional cooking methods reduced the allergenicity of egg proteins, particularly frying, and this reduction was associated with structural changes that could contribute to the destruction or masking of epitopes of egg allergens. PRACTICAL APPLICATION: Egg allergy has a serious impact on public health, and there is no ideal treatment method at present. This study demonstrated that four traditional cooking methods (boiling, steaming, baking, and frying) reduced the allergenicity of egg proteins, especially frying, and the results will provide a basis for the development of hypoallergenic egg products.

sRAGE-binding and antimicrobial bioactivities of soy and pea protein after heating and in vitro infant digestion

During infant formula production, proteins are always heated, potentially affecting their digestibility and the bioactivities of resulting peptides. Although plant proteins are a promising dairy alternative for infant formula, they remain understudied, necessitating further investigations. Therefore, this research aimed to fill this gap by assessing the impact of different heating modes on soy protein (SP) and pea protein (PP), focusing on glycation levels, peptide formation during in vitro infant digestion, and immune protection potential (sRAGE-binding and antimicrobial activities) of the resulting peptides. Consequently, dry heating led to increased glycation and glycated peptide production, particularly with higher glycation in PP than SP. Moreover, PP exhibited an overall stronger sRAGE-binding capacity than SP, regardless of heating and digestion conditions. Regarding antimicrobial activity, both SP and PP-derived peptides displayed reduced effectiveness against Enterobacter cloacae after dry heating. Additionally, Staphylococcus epidermidis was differently inhibited, where PP-derived peptides showed inherent inhibition. The primary determinant of sRAGE-binding and antimicrobial potential in digestion-derived peptides was the protein source. Subsequent bioinformatics analysis predicted 519 and 133 potential antimicrobial peptides in SP and PP, respectively. This study emphasises the importance of protein source for infant formula to ensure infant health.

A cross-sectional study on stool- and gastrointestinal-related outcomes of Mexican infants consuming different formulae

BACKGROUND

Immaturities present at birth, such as in the gut microbiome and digestive, nervous, and immune system, resolve with time. Nevertheless, this may result in mild digestive symptoms early in life, particularly in formula-fed infants. Formula composition and processing may impact this discomfort. This study therefore aimed to assess stool characteristics and gastrointestinal symptoms of healthy infants fed different formulae.

METHODS

A multicenter, cross-sectional, observational trial was performed in Mexico between November 2019 and January 2022, where exclusively formula-fed infants (n = 342, aged 1-4 months) were studied in four groups based on their existing formula use. Feeding was continued per practice following label instructions. For 7 days, parents/caregivers were requested to record fecal characteristics, using the Amsterdam Infant Stool Scale, and rate gastrointestinal symptoms. Stool samples were collected to determine pH, dry matter content, and fecal calprotectin levels.

RESULTS

Most infants had a soft/formed stool consistency, although odds for hard stools were different between groups. Gastrointestinal symptom scores revealed significant differences for burping and diarrhea, while other symptoms did not differ between groups. No significant differences between groups were found for stool frequency, dry matter content, and fecal pH. Although calprotectin was within the expected healthy ranges, significant differences among groups were seen. Furthermore, calprotectin significantly correlated with the severity of the gastrointestinal symptoms burping, flatulence, abdominal distension, and diarrhea.

CONCLUSIONS

Differences in stool characteristics and specific differences in gastrointestinal symptoms were observed between different formula brand users. This may potentially be explained by the different composition and processing of the formulae, although there are multiple factors that influence the assessed outcomes.

TRIAL REGISTRATION

The study was registered in the Netherlands Trial Registry (NL7805), linked to https://trialsearch.who.int/ , on 11/06/2019.

Allergen Stability in Food Allergy: A Clinician's Perspective

PURPOSE OF REVIEW

The globally rising food allergy prevalence is associated with the urgent need for new disease prevention methods, efficient treatment, and reliable risk assessment methods for characterization of food allergens. Due to inter-individual variations in the digestive system, food allergens are degraded to a different extent in each person. Food processing also influences allergen digestion.

RECENT FINDINGS

In this review, we provide an overview of the digestive system with focus on relevance for food allergy. Main food proteins causing allergic reactions are evaluated, and the combined role of food processing and digestion for allergen stability is highlighted. Finally, clinical implications of this knowledge are discussed. Recent literature shows that allergen digestibility is dependent on food processing, digestive conditions, and food matrix. Digestion affects proteins allergenicity. It is currently not possible to predict the immunogenicity of allergens solely based on protein stability.

Non-covalent binding of whey protein isolate after ultrasound pretreatment to epigallocatechin gallate: Effects on immune response and gut microbiota in BALB/c mice

Cow's milk is one of the "big eight" most common allergenic foods, and β-lactoglobulin and α-Lactalbumin in whey protein are two major allergens of cow's milk protein. An effective strategy for reducing the allergenicity of whey protein is needed. In the present study, protein-EGCG complexes were obtained through non-covalent interactions between untreated or sonicated whey protein isolate (WPI) and epigallocatechin gallate (EGCG), and the allergenicity of complexes was assessed in vivo. The results showed that SWPI-EGCG complex possesses low allergenicity in BALB/c mice. As compared with untreated WPI, SWPI-EGCG complex had less effect on the body weight and organ indexes. Moreover, SWPI-EGCG complex could alleviate the WPI induced allergic reactions and intestinal damage of mice by decreasing the secretion of IgE, IgG, histamine, mMCP-1, modulating the balance of Th1/Th2 and Treg/Th17 response, and increasing the diversity of intestinal flora and the relative abundances of probiotic bacteria. These findings indicate that the interaction of sonicated WPI with EGCG could reduce the allergenicity of WPI, which could provide a new strategy for reducing food allergenicity.

Update on Nutrition and Food Allergy

Food-induced anaphylaxis is an immediate adverse reaction, primarily triggered by the cross-linking of allergen-specific immunoglobulin (Ig) E bound to the high-affinity IgE receptor (FcεRI) on mast cells (MCs) after re-exposure to the same food allergen [...]

Effect of Phosphorylation on the Structure and Emulsification Properties of Different Fish Scale Gelatins

This study aimed to investigate the effect of phosphorylation on the structure and emulsification of Coregonus peled, Esox lucius and Grass carp scale gelatin. Fourier transform infrared spectroscopy (FTIR) and endogenous fluorescence spectra showed that the structures of the three fish scale gelatins changed. Additionally, the surface hydrophobicity index of the three fish scale gelatins increased by 36.72, 31.42 and 111.67, respectively, after 1 h of phosphorylation, and the surface tension decreased by 17.27, 32.58 and 18.7 mN/m, respectively. The emulsification activity index increased by 115.86, 155.22 and 45.52 m²/g, and the emulsification stability index increased by 98.37, 256.77 and 169.61 min, respectively. The structure of fish scale gelatin changed after phosphorylation, which resulted in the improvement of emulsification. This work will provide useful information to understand the relationship between the structure and function of gelatin.

In vitro simulated semi-dynamic gastrointestinal digestion: evaluation of the effects of processing on whey proteins digestibility and allergenicity

The effect of thermal processing on digestibility of milk proteins should be better understood as this can greatly affect their immunoreactivity. The aim of this study was to evaluate the...

Transport of a Peptide from Bovine αs1-Casein across Models of the Intestinal and Blood-Brain Barriers

The effect of food components on brain growth and development has attracted increasing attention. Milk has been shown to contain peptides that deliver important signals to the brains of neonates and infants. In order to reach the brain, milk peptides have to resist proteolytic degradation in the gastrointestinal tract, cross the gastrointestinal barrier and later cross the highly selective blood–brain barrier (BBB). To investigate this, we purified and characterized endogenous peptides from bovine milk and investigated their apical to basal transport by using human intestinal Caco-2 cells and primary porcine brain endothelial cell monolayer models. Among 192 characterized milk peptides, only the α_S1-casein peptide ¹⁸⁵PIGSENSEKTTMPLW¹⁹⁹, and especially fragments of this peptide processed during the transport, could cross both the intestinal barrier and the BBB cell monolayer models. This peptide was also shown to resist simulated gastrointestinal digestion. This study demonstrates that a milk derived peptide can cross the major biological barriers in vitro and potentially reach the brain, where it may deliver physiological signals.