Modification of protein structures by altering the whey protein profile and heat treatment affects in vitro static digestion of model infant milk formulas

Incorporation of β-carotene O/W emulsions into dairy foods: Impact of the colloidal stability during in vitro digestion on the lipolysis and bioaccessibility

O/W emulsions have been proposed as delivery systems of lipophilic bioactive compounds into water-based foods. This work aimed to study the impact of the food matrix on the colloidal stability of β-carotene-loaded O/W emulsion incorporated into dairy products (milk and yogurt) before and during in vitro gastrointestinal (GI) digestion. The relationship between colloidal stability, lipolysis and β-carotene bioaccessibility was also evaluated. The colloidal stability of the O/W emulsion was maintained once it was incorporated into dairy products and during GI conditions, without a significant impact of the food matrix. However, lipolysis, as FFA release, was faster and higher once the O/W emulsion (64.58 ± 2.76 %) was co-digested with dairy products (>81 %). Nevertheless, they presented non-significant differences in β-carotene bioaccessibility (38-44 %), thus dairy matrices would limit mixed micelles formation or β-carotene micellarization. This work provides valuable insight for designing dairy products fortified with bioactive compounds by using emulsions as delivery systems.

Proteomic and peptidomic profiling of spirulina-fortified probiotic powder formulations during in vitro digestion

This study reports on the influence of lactic acid fermentation on the proteomic and peptidomic profiles of spirulina protein isolate (SPI)-fortified, freeze-dried powders containing living Lacticaseibacillus rhamnosus GG (LGG) cells during in vitro digestion. For comparison, powders fortified with whey protein isolate (WPI) and pea protein isolate (PPI) were also evaluated. Prior to freeze-drying, the powder precursors were either non-treated or fermented. Capillary SDS-PAGE electropherograms revealed a mild proteolytic effect due to fermentation. C-phycocyanin (SPI) and β-lactoglobulin (WPI) showed the highest resistance to pepsinolysis. All samples were responsive to pancreases, with fermented WPI showing the lowest responsiveness. Fermentation enhanced the degree of hydrolysis (DH) in gastric chymes, whereas in intestinal chymes, DH followed the order SPI > PPI > WPI, with fermentation showing no significant impact. A total of 6, 11, and 52 potential bioactive peptide sequences, associated with various beneficial activities, were identified in the SPI, PPI, and WPI digesta, respectively. The highest amino acid bioaccessibilities were observed for cysteine and methionine in SPI, isoleucine and arginine in PPI, and glycine in WPI. In conclusion, fortifying probiotic formulations with protein isolates offers secondary health benefits, stemming from the release of bioactive peptides and bioaccessible essential amino acids.

Dairy Foods: A Matrix for Human Health and Precision Nutrition-Effect of processing infant milk formula on protein digestion and gut barrier health (in vitro and preclinical)

The infant gut is immature and permeable with high gastric pH, low protease activities, and underdeveloped intestinal architecture. Protein digestion in the upper gastrointestinal tract of infants is slow and incomplete. During manufacture, infant milk formula (IMF) is typically heat-treated so it is safe for human consumption. This heat treatment causes denaturation and aggregation of milk proteins, and formation of undesirable Maillard reaction products. The aim of this review is to critically summarize the in vitro and preclinical data available on the effect of IMF thermal processing on protein digestion and gut barrier physiology in the immature infant gut. Recent research efforts have focused on reducing thermal loads during IMF manufacturing by sourcing ingredients with low thermal loads, by reducing temperatures during IMF processing itself, and by seeking alternative processing technologies. This review also aims to evaluate whether these thermal reductions have a knock-on effect on protein digestion and gut barrier health in the infant. The ultimate aim is to create a safe next-generation IMF product that more closely mimics human breast milk in its protein digestion kinetics and its ability to promote gut barrier maturity in the infant.

Effect of Different Ratios of α-Lactalbumin to β-Casein in Infant Formula on True Ileal Digestibility and Intestinal Morphology of Suckling Piglets

Breast milk (BM) is the optimal nutrition source for infants, providing highly digestible proteins. In contrast, the digestibility of proteins in infant formula (IF) varies, influenced by differences in proteins such as α-lactalbumin (α-La) and β-casein (β-CN). This study aimed to evaluate the true ileal digestibility (TID) of amino acids (AAs) in BM and IF with varying α-La and β-CN contents using neonatal piglets. Twenty-four 11-day-old piglets (4 groups; 6 replicates/group) received either a nitrogen-free diet, IF (high infant formula (HIF) with 1.74 g/100 α-La and 2.3 g/100 β-CN; low infant formula (LIF) with 1.07 g/100 α-La and 1.85 g/100 β-CN), or BM (1.82 g/100 α-La and 3.05 g/100 β-CN) for 7 days after 3 prefeed days. IF had higher concentrations of nitrogen, serine, threonine, and proline than BM. Glutamic acid was the most abundant AA in IF and BM, while methionine in BM and LIF or tryptophan in HIF was the least. BM showed the highest TID of AAs, with the LIF had the lowest. The HIF group's TID for AAs, especially tryptophan, was similar to BM and significantly better than LIF. These results suggest that adjusting the α-La and β-CN ratio in IF can improve AA digestibility, approaching BM levels.

Effect of a minimal processing route for the production of infant formulas on their sensory properties

Infant formulas (IF), the sole adequate substitute to human milk, undergo several thermal treatments during production that can damage milk proteins and promote the formation of Maillard reaction products, modifying nutritional and sensory properties. The aim of this study was to determine the effect of a minimal processing route based on membrane filtration associated with different levels of heat treatment, on the odor, taste, texture, and color attributes of IF, then to compare with those of commercial milks. Three experimental IF (produced with membrane filtration associated with low [T-], medium [T+], or high thermal treatments [T+++]) were evaluated. Triangular tests conducted with a panel of 50 adults highlighted clear disparities between all the IF. The same panel applied the check-all-that-apply (CATA) method to evaluate the IF: the range of variability between T- and T+++ was similar to that between the 2 commercial IF, and the sensory characteristics of the experimental IF were not far from the commercial brands for flavor and texture attributes. Analysis performed on the citation frequencies for each descriptor differentiated T-/T+ from T+++, but all the experimental IF were described with positive sensory characteristics, unlike one commercial IF. Volatile organic compounds (VOC) content of IF with low and high thermal treatments were analyzed. Forty VOC were identified by GC-MS. T- contained a higher quantity of VOC than T+++, except for benzaldehyde (Maillard reaction product), and aldehydes (oxidation-related products) were the most represented compounds. In conclusion, the processing was associated with sensory differences among IF, but no marked difference in flavors was found according to CATA and physicochemical analysis. Additionally, no unpleasant sensory descriptors were noted. This shows that the minimally processed route leads to IF that could fit well within the market from a sensory point of view.

Establishing a novel covalent complex of wheat gluten with tea polyphenols: Structure, digestion, and action mechanism

Plant-based proteins represent a more sustainable alternative, the approaches to modify and enhance their functionality and application are focused on. Covalent interaction could significantly modify the structure and function properties of protein. This study investigated the effects of covalent interaction between wheat gluten and tea polyphenols on the structure, aggregation, stability, and digestive properties of their covalent complex, as well as the possible action mechanism. The results showed that tea polyphenols could interact with gluten via covalent bonds (CN and/or CS), while tea polyphenols also acted as a bridge connecting gluten molecules, thus making covalent complex to show the larger particle sizes. This covalent interaction significantly changed the secondary structure, tertiary structure, and surface hydrophobicity of gluten. Moreover, covalent complex exhibited the high polyphenols bioaccessibility during in vitro digestion. The peptide bonds of covalent complex were mainly broken in gastric digestion, while the covalent bonds between tea polyphenols and gluten were completely destroyed in intestinal digestion. In addition, their digestates exhibited excellent antioxidant capability. All results suggest that wheat gluten have potential to prepare functional carrier for transporting active compounds and protecting them during digestion.

Regulation on Aggregation Behavior and In Vitro Digestibility of Phytic Acid-Whey Protein Isolate Complexes: Effects of Heating, pH and Phytic Acid Levels

The impact of heat treatment, pH and phytic acid (PA) concentration on the aggregation behavior and digestibility of whey protein isolate (WPI) was investigated. The experimental results indicated that below the isoelectric point of WPI, heat treatment and elevated PA levels significantly increased turbidity and particle size, leading to the aggregation of WPI molecules. No new chemical bonds were formed and the thermodynamic parameters ΔH < 0, ΔS > 0 and ΔG < 0 suggested that the interaction between PA and WPI was primarily a spontaneous electrostatic interaction driven by enthalpy. After the small intestine stage, increasing phytic acid levels resulted in a significant decrease in hydrolysis degree from 16.2 ± 1.5% (PA0) to 10.9 ± 1.4% (0.5% PA). Conversely, above isoelectric point of WPI, there was no significant correlation between the presence of PA and the aggregation behavior or digestion characteristics of WPI. These results were attributed to steric hindrance caused by PA-WPI condensates, which prevented protease binding to hydrolysis sites on WPI. In summary, the effect of PA on protein aggregation behavior and digestive characteristics was not simply dependent on its presence but largely on the aggregation degree of PA-WPI induced by heat treatment, pH and PA concentration. The findings obtained here suggested that phytic acid may be utilized as an agent to modulate the digestion characteristics of proteins according to production requirements. Additionally, the agglomerates formed by heating phytic acid and protein below the isoelectric point could also be utilized for nutrient delivery.

In vitro digestion and functional properties of bovine β-casein: A comparison between adults and infants

Gastrointestinal digestibility behavior, structural and functional characteristics of bovine β-casein (β-CN) were studied in vitro under infant and adult conditions. This direct comparison helps reveal the effects of different physiological stages on the digestive behavior of β-CN. Not only was the degree of hydrolysis (DH) of β-CN analyzed, but also the changes in its digestive morphology, microstructure, and secondary structure during digestion were explored in depth. Meanwhile, we focused on the physicochemical properties of β-CN digesta, including solubility, emulsifying and foaming properties, as well as their functional properties, such as antimicrobial and antioxidant activities. Key results showed that β-CN underwent more extensive hydrolysis in the adult digestion model, with approximately twice the DH compared to the infant model. The adult model exhibited faster digestion kinetics, less protein flocculation, and a more loosened secondary structure, indicating a more efficient digestion process. Notably, the digesta from the adult model displayed significantly improved solubility and emulsifying properties, and also enhanced antioxidant capacities, with significantly better inhibition of two common pathogenic bacteria than the infant model, and an average increase in the diameter of the inhibition zone of approximately 2 mm. These findings underscore the differential digestive behavior and functional potential of β-CN across physiological stages. This comprehensive assessment approach contributes to a more comprehensive insight into the digestive behavior of β-CN. Therefore, we conclude that producing products from unmodified β-CN may be more suitable for the adult population, and that the digesta in the adult model exhibit higher functional properties.

Infant growth and tolerance with a formula based on novel native demineralized whey: A randomized double-blind pilot study

OBJECTIVES

The aim of the study was to evaluate the effects on infant growth and tolerance of a Test infant formula based on a novel whey extraction and demineralization process, compared to a Standard formula and a breastfed reference arm.

METHODS

Healthy term infants (n = 61) aged up to 21 days were randomized to Test or Control formula. A breastfed group (n = 39) served as a reference. Growth, tolerance, adverse events, and sleep were evaluated every month until 6 months of age. Plasma amino-acid concentrations at 3 months of age were measured in a subgroup population.

RESULTS

Growth curves of all infants globally agreed with World Health Organization standards across the 6-month period study. Regarding tolerance, no difference between the formula-fed groups was observed on daily number of crying episodes, intensity or time to onset of regurgitations, and stool frequency or consistency, except at 5 months with infants in the Control group having more watery stools. Plasma concentration of some amino acids differed between the groups, especially tryptophan concentration which was higher in infants fed with the Test formula. In parallel, total sleep duration was longer in these infants at 2, 3, and 5 months of age, corresponding to an increase in daytime sleep.

CONCLUSIONS

Test formula supported an adequate infant growth from birth to 6 months of age and was well-tolerated by all infants. An increase in total sleep at several months was also observed with the Test formula.

The impact of complexation or complex coacervation of lactoferrin and osteopontin on simulated infant gastrointestinal digestion, intestinal inflammation, and in vivo bone development

Lactoferrin (LF) and osteopontin (OPN) are bioactive milk proteins which can form heteroprotein complexes and complex coacervates. This research studied the effect of LF-OPN complexation and complex coacervation on the simulated infant gastrointestinal digestion of LF with subsequent examination of gut and bone health bioactivities in preclinical models. In an infant digestion model, the proteolytic profile of LF was unaltered by the pre-association of LF and OPN. Gastric proteolysis of LF was increased when the model gastric pH was reduced from 5.3 to 4.0, but less so when complexed with OPN. In a model of intestinal inflammation, undigested (79% inhibition) and gastric digestates (26% inhibition) of LF, but not gastrointestinal digestates, inhibited lipopolysaccharide (LPS)-induced NF-κB activation in intestinal epithelial cells. LF-OPN complexation sustained the inhibitory effect (21-43% of the undigested effect, depending on the type of complex) of LF after gastrointestinal digestion, suggesting that the peptides produced were different. In a neonatal rodent model used to study bone development, coacervating LF and OPN improved bone structures with a significant increase of trabecular proportion (BV/TV increase by 21.7%). This resulted in an 11.3% increase in stiffness of bones. Feeding the LF and OPN proteins in coacervate format also increased the levels of OPN, P1NP and M-CSF in blood, signifying a more pronounced impact on bone development. This research demonstrated that LF-OPN complexation and complex coacervation can delay simulated infant gastrointestinal digestion of LF and protect or improve the bioactivity of the proteins.

A protectant for Lactobacillus rhamnosus based on whey protein isolate and isomalt: Stress resistance and underlying mechanisms

Probiotics are exposed to a variety of abiotic and biotic stresses during food fermentation and production, such as acidity, heat, osmolality, and oxidation, which affect their metabolic activity and efficiency. Therefore, it is essential to develop new protective agents to maintain the activity and stability of probiotics. This study introduces a new protectant, spray-dried whey protein isolate (WPI) and isomaltose (ISO). We evaluated the effects of four WPI-ISO ratios (1:0, 2:1, 1:1, 1:2) on the physical properties, including moisture content, water activity (aw), wettability, and glass transition temperature. In addition, we evaluated the environmental tolerance of Lactobacillus rhamnosus to different WPI-ISO ratios under thermal, storage, and simulated gastrointestinal conditions. The results showed that the moisture content (< 7 %) and water activity (< 0.3) of the protectant and probiotic powders met storage stability requirements. The moisture content, water activity, wettability index (WI), and glass transition temperature decreased significantly with the addition of isomalt, thereby improving the pressure resistance of L. rhamnosus through the synergistic effect of WPI and ISO. The WPI-ISO protectant not only improved the environmental tolerance and wettability of probiotics by reducing the moisture content and water activity but also significantly improved the survival rate of L. rhamnosus under various stress conditions such as high temperature and gastrointestinal environment. L. rhamnosus maintains good activity with a viable bacterial count of over 9 lg CFU/g after 90 days of storage, demonstrating effective protection against the environment stress. This study provides a promising new strategy to improve the stability of probiotics in the food industry.

In vitro gastrointestinal digestion of cow's and sheep's dairy products: Impact of species and structure

Sheep's milk (SM) is known to differ from cow's milk (CM) in nutritional composition and physicochemical properties, which may lead to different digestion behaviours. This work aimed to investigate the impact of the species (cow vs sheep) and the structure (milk vs yogurt) on the digestion of dairy products. Using an in vitro static gastrointestinal digestion model, CM, SM, cow's milk yogurt (CY) and sheep's milk yogurt (SY) were compared on particle size evolution, microscopic observations, degree of lipolysis, degree of proteolysis, specific protein degradation and calcium bioaccessibility. Species and structure affected particle size evolution during the gastric phase resulting in smaller particles for yogurts compared to milks as well as for CM products compared to SM products. Species impacted lipid composition and lipolysis, with SM products presenting higher short/medium-chain fatty acids content and higher intestinal degree of lipolysis. Proteolysis was influenced by structure, with milks showing higher intestinal degree of proteolysis compared to yogurts. Caseins were digested faster in CM, ⍺-lactalbumin was digested faster in SM despite its higher concentration, and during gastric digestion β-lactoglobulin was more degraded in CM products compared to SM products and more in yogurts compared to milks. Lastly, SM products released more bioaccessible calcium than CM products. In conclusion, species (cow vs sheep) impacted more the digestion compared to the structure (milk vs yogurt). In fact, SM was different from CM mainly due to a denser protein network that might slow down the accessibility of the enzyme to its substrate which induce a delay of gastric disaggregation and thus lead to slower the digestion of the nutrients.

Novel fungal alternative proteins from Penicillium limosum for enhancing structural and functional properties of plant-based meat analogues

Fungal proteins are excellent novel protein resources due to their high nutritional value and biological activity. In this study, a non-toxic strain of Penicillium limosum with a high biomass yield, protein, and essential amino acid contents, was isolated from wheat Qu (solid-state fermentation starter culture). Pea protein isolate (PPI) and P. limosum mycelial protein powder were extruded to prepare high-moisture meat analogues (HMMA), and their structural and functional properties were evaluated. Compared with 100% PPI, the addition of 5% mycoprotein enhanced the viscosity, gelling properties, chewiness, fibrous degree and in vitro protein digestibility (68.65%) of HMMA. Protein aggregates formed during high temperature extrusion, which increased the oil absorption capacity of HMMA (5% MY substitution). Conversely, their water absorption capacity indices were reduced by 5%. These findings provide a theoretical basis for the functional application of novel fungal alternative proteins.

Exploring the Role of Lactoferrin in Managing Allergic Airway Diseases among Children: Unrevealing a Potential Breakthrough

The prevalence of allergic diseases has dramatically increased among children in recent decades. These conditions significantly impact the quality of life of allergic children and their families. Lactoferrin, a multifunctional glycoprotein found in various biological fluids, is emerging as a promising immunomodulatory agent that can potentially alleviate allergic diseases in children. Lactoferrin's multifaceted properties make it a compelling candidate for managing these conditions. Firstly, lactoferrin exhibits potent anti-inflammatory and antioxidant activities, which can mitigate the chronic inflammation characteristic of allergic diseases. Secondly, its iron-binding capabilities may help regulate the iron balance in allergic children, potentially influencing the severity of their symptoms. Lactoferrin also demonstrates antimicrobial properties, making it beneficial in preventing secondary infections often associated with respiratory allergies. Furthermore, its ability to modulate the immune response and regulate inflammatory pathways suggests its potential as an immune-balancing agent. This review of the current literature emphasises the need for further research to elucidate the precise roles of lactoferrin in allergic diseases. Harnessing the immunomodulatory potential of lactoferrin could provide a novel add-on approach to managing allergic diseases in children, offering hope for improved outcomes and an enhanced quality of life for paediatric patients and their families. As lactoferrin continues to capture the attention of researchers, its properties and diverse applications make it an intriguing subject of study with a rich history and a promising future.

Minimal processed infant formula vs. conventional shows comparable protein quality and increased postprandial plasma amino acid kinetics in rats

During industrial processing, heat treatments applied to infant formulas may affect protein digestion. Recently, innovative processing routes have been developed to produce minimally heat-processed infant formula. Our objective was to compare the in vivo protein digestion kinetics and protein quality of a minimally processed (T−) and a heat-treated (T+++) infant formula. Sixty-eight male Wistar rats (21 d) were fed with either a diet containing 40 % T− (n 30) or T+++ (n 30), or a milk protein control diet (n 8) during 2 weeks. T− and T+++ rats were then sequentially euthanised 0, 1, 2, 3 or 6 h (n 6/time point) after ingestion of a meal containing their experimental diet. Control rats were euthanised 6 h after ingestion of a protein-free meal to determine nitrogen and amino acid endogenous losses. Nitrogen and amino acid true caecal digestibility was high for both T− and T+++ diets (> 90 %), but a tendency towards higher nitrogen digestibility was observed for the T− diet (96·6 ± 3·1 %) compared with the T+++ diet (91·9 ± 5·4 %, P = 0·0891). This slightly increased digestibility led to a greater increase in total amino acid concentration in plasma after ingestion of the T− diet (P = 0·0010). Comparable protein quality between the two infant formulas was found with a digestible indispensable amino acid score of 0·8. In conclusion, this study showed that minimal processing routes to produce native infant formula do not modify protein quality but tend to enhance its true nitrogen digestibility and increase postprandial plasma amino acid kinetics in rats.

Wheat gluten deamidation: structure, allergenicity and its application in hypoallergenic noodles

BACKGROUND

Wheat gluten (WG) containing gliadin and glutenin are considered the main allergens in wheat allergy as a result of their glutamine-rich peptides. Deamidation is a viable and efficient approach for protein modifications converting glutamine into glutamic acid, which may have the potential for allergenicity reduction of WG.

RESULTS

Deamidation by citric acid was performed to investigate the effects on structure, allergenicity and noodle textural properties of wheat gluten (WG). WG was heated at 100 °C in 1 m citric acid to yield deamidated WG with degrees of deamidation (DD) ranging from DWG-25 (25% DD) to DWG-70 (70% DD). Fourier-transform infrared and intrinsic fluorescence spectroscopy results suggested the unfolding of WG structure during deamidation, and sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed molecular weight shifts at the 35-63 kDa region, suggesting that the deamidation mainly occurred on low molecular weight glutenin subunits and γ- gliadin of the WG. An enzyme-linked immunosorbent assay of deamidated WG revealed a decrease in absorbance and immunoblotting indicated that the intensities of protein bands at 35-63 kDa decreased, which suggested that deamidation of WG might have caused a greater loss of epitopes than the generation of new epitopes caused by unfolding of WG, and thereby reduction of the immunodominant immunoglobulin E binding capacity, ultimately leading to the decrease in allergenicity. DWG-25 was used in the preparation of recombinant hypoallergenic noodles, and the hardness, elasticity, chewiness and gumminess were improved significantly by the addition of azodicarbonamide.

CONCLUSION

The present shows the potential for deamidation of the WG products used in novel hypoallergenic food development. © 2023 Society of Chemical Industry.

Digestive properties and peptide profiles exhibited significant differences between skim camel milk and bovine milk powder after static in vitro simulated infant gastrointestinal digestion

This study aims to analyze the differences in digestion properties and peptide profiles between the skim camel and bovine milk powder after static in vitro simulated infant gastrointestinal digestion. The hydrolysis degree of camel milk proteins exceeded by 13.18% that of bovine milk. The concentration and release rate of free amino groups in the camel milk digesta was higher than that of bovine milk powder, which was likely due to the higher β-/αs-casein ratio and larger casein micelle size in camel milk. Camel milk powder presented higher β-CN coverage and comparatively shorter bioactive peptides compared to bovine milk powder. The anti-inflammatory peptide KVLPVPQ displayed the highest abundance in camel milk powder. Outcomes of this study showed that camel milk proteins possessed superior digestibility and unique peptides, which outlined the potential nutritional implications of camel milk for infants.

Nutrition in chronic inflammatory conditions: Bypassing the mucosal block for micronutrients

Nutritional Immunity is one of the most ancient innate immune responses, during which the body can restrict nutrients availability to pathogens and restricts their uptake by the gut mucosa (mucosal block). Though this can be a beneficial strategy during infection, it also is associated with non-communicable diseases-where the pathogen is missing; leading to increased morbidity and mortality as micronutritional uptake and distribution in the body is hindered. Here, we discuss the acute immune response in respect to nutrients, the opposing nutritional demands of regulatory and inflammatory cells and particularly focus on some nutrients linked with inflammation such as iron, vitamins A, Bs, C, and other antioxidants. We propose that while the absorption of certain micronutrients is hindered during inflammation, the dietary lymph path remains available. As such, several clinical trials investigated the role of the lymphatic system during protein absorption, following a ketogenic diet and an increased intake of antioxidants, vitamins, and minerals, in reducing inflammation and ameliorating disease.

Fava bean (Vicia faba L.) protein concentrate added to beef burgers improves the bioaccessibility of some free essential amino acids after in vitro oral and gastrointestinal digestion

The influence of partial replacement of animal protein by plant-based ingredients on the protein digestibility of beef burgers was investigated. Beef burgers were supplemented with fava bean protein concentrate (FB) or a mixture of FB and flaxseed flour (FBFS), both processed by extrusion, at different levels: 0 (control), 10, 15, and 20 % (w/w). A pilot sensory analysis was conducted to select the percentage of flour inclusion for further assays: control, 10 % FB, and 10 % FBFS. Protein digestibility, amino acid profile, and protein secondary structure of these burgers after in vitro oral and gastrointestinal digestion were studied. In vitro boluses were prepared with the AM2 masticator, simulating normal mastication, and static in vitro digestion of boluses was performed according to the INFOGEST method. Inclusion of 10 % FB in beef burgers did not alter their flavour or tenderness compared to the control, whereas tenderness and juiciness scored slightly higher for the 10 % FBFS burgers compared to 15 % and 20 % FBFS ones. Poor lipid oxidative stability during storage was observed with 10 % FBFS burgers. Total protein content was significantly higher (p < 0.05) in 10 % FB burgers than in control burgers after in vitro oral digestion. Additionally, 10 % FB burgers presented higher amounts of free essential amino acids like isoleucine, leucine, phenylalanine, and valine at the end of digestion, as well as methionine, tyrosine, and histidine. Partial substitution of meat protein by 10 % FB improves the nutritional profile of beef burgers, without altering their sensory qualities.

The aggregation of casein micelles induced by Ca2+ during in vitro digestion: effects on the release of loaded anthocyanins

Colloidal calcium phosphate (CCP) confers a modifiable structure to micellar casein (MC), which endows it with potential advantages as a delivery carrier. However, it is difficult to achieve multipattern release of the core material in the intestine with MC as a single wall. In this study, we prepared an anthocyanin-casein-based delivery system utilizing MC with different freezing degrees as the wall material with the objective of achieving the controlled release of anthocyanin as the model core in the intestine. The results showed that freezing could significantly reduce the CCP level up to 50%. Static in vitro simulated digestion with the addition of exogenous Ca2+ showed that the designed delivery system exhibited low anthocyanin release (15%-35%) in the gastric tract. The pattern of release in the intestine depended on the CCP dissociation degree. High and low dissociation degrees corresponded to slow release (from 15% to 65% within 2 h) and burst release (from 35% to 90% within 5 min), respectively. WAXS/SAXS analysis revealed that exogenous serum Ca2+ inherent in simulated gastric fluid and endogenous serum Ca2+ induced by CCP dissociation was synergistically involved in the reconstitution of CCP-mediated nanoclusters and large aggregates. The freezing degree of MC determined the endogenous serum Ca2+ level, which influenced the gastric aggregation behavior of wall MC and ultimately led to a fairly different gastrointestinal release behavior of anthocyanins.

Protein ingredient quality of infant formulas impacts their structure and kinetics of proteolysis under in vitro dynamic digestion

Infant formula (IF) is a complex matrix requiring numerous ingredients and processing steps. The objective was to understand how the quality of protein ingredients impacts IF structure and, in turn, their kinetics of digestion. Four powdered IFs (A/B/C/D), based on commercial whey protein (WP) ingredients, with different protein denaturation levels and composition (A/B/C), and on caseins with different supramolecular organisations (C/D), were produced at a semi-industrial level after homogenization and spray-drying. Once reconstituted in water (13 %, wt/wt), the IF microstructure was analysed with asymmetrical flow field-flow fractionation coupled with multi-angle light scattering and differential refractometer, transmission electron microscopy and electrophoresis. The rehydrated IFs were subjected to simulated infant in vitro dynamic digestion (DIDGI®). Digesta were regularly sampled to follow structural changes (confocal microscopy, laser-light scattering) and proteolysis (OPA, SDS-PAGE, LC-MS/MS, cation-exchange chromatography). Before digestion, different microstructures were observed among IFs. IF-A, characterized by more denatured WPs, presented star-shaped mixed aggregates, with protein aggregates bounded to casein micelles, themselves adsorbed at the fat droplet interface. Non-micellar caseins, brought by non-micellar casein powder (IF-D) underwent rearrangement and aggregation at the interface of flocculated fat droplets, leading to a largely different microstructure of IF emulsion, with large aggregates of lipids and proteins. During digestion, IF-A more digested (degree of proteolysis + 16 %) at 180 min of intestinal phase than IF-C/D. The modification of the supramolecular organisation of caseins implied different kinetics of peptide release derived from caseins during the gastric phase (more abundant at G80 for IF-D). Bioactive peptide release kinetics were also different during digestion with IF-C presenting a maximal abundance for a large proportion of them. Overall, the present study highlights the importance of the structure and composition of the protein ingredients (WPs and caseins) selected for IF formulation on the final IF structure and, in turn, on proteolysis. Whether it has some physiological consequences remains to be investigated.

Oral and gastrointestinal nutrient bioaccessibility of gluten-free bread is slightly affected by deficient mastication in the elderly

The main goal of this work was to investigate the impact of impaired mastication on nutrient bioaccessibility of gluten-free bread in the elderly. In vitro boluses were produced with the AM² masticator by using two types of programming: normal mastication (NM) and deficient mastication (DM). Static in vitro gastrointestinal digestion was performed with the digestive physiology conditions of the elderly. Subsequently, the granulometric properties of the in vitro boluses produced, their starch and protein digestibility, and lipid peroxidation after in vitro oral and gastrointestinal digestion were evaluated. DM boluses presented higher proportions of large particles, resulting in insufficiently fragmented boluses. A delay in oral starch digestion was observed in DM boluses, probably due to the presence of larger particles that limited the bolus-saliva exchanges. Furthermore, DM boluses exhibited a lower degree of protein hydrolysis at the end of gastric digestion, whereas no differences were observed for protein hydrolysis, sugar release, and lipid peroxidation at the end of digestion (intestinal phase). The results of this study show that impaired mastication somewhat delays the nutrient bioaccessibility of the gluten-free bread tested. Such understanding of the effect of oral decline on the nutrient bioaccessibility of foods is crucial when designing food commodities with enhanced functionalities for the elderly.

Wahab N. In Vitro Infant Digestion of Whey Proteins Isolate-Lactose

The model in vitro protein digestion technique has received greater attention due to providing significant advantages compared to in vivo experiments. This research employed an in vitro infant digestive static model to examine the protein digestibility of whey proteins isolate-lactose (WPI-Lac). The polyacrylamide gel electrophoresis (PAGE) pattern for alpha-lactalbumin of WPI at 60 min showed no detectable bands, while the alpha-lactalbumin of the WPI-Lac was completely digested after 5 min of gastric digestion. The beta-lactoglobulin of the WPI-Lac was found to be similar to the beta-lactoglobulin of the WPI, being insignificant at pH 3.0. The alpha-lactalbumin of the WPI decreased after 100 min of duodenal digestion at pH 6.5, and the WPI-Lac was completely digested after 60 min. The peptides were identified as ~2 kilodalton (kDa) in conjugated protein, which indicated that the level of degradation of the protein was high, due to the hydrolysis progress. The conjugated protein increased the responsiveness to digestive proteolysis, potentially leading to the release of immunogenic protein by lactose, and to the creation of hypoallergenic protein.

Development of a human milk protein concentrate from donor milk: Impact of the pasteurization method on static in vitro digestion in a preterm newborn model

The impact of high temperature short time (HTST, 72 °C, 15 s), Holder pasteurization- (63 °C, 30 min) and high hydrostatic pressure (HHP, 600 MPa-10 min) was evaluated on the digestibility of human milk protein concentrate (HMPC) by using a static in vitro gastrointestinal digestion system. The results showed that the processing steps used to produce the HMPC induced a decrease in readily available nitrogen (non-protein nitrogen and peptides). Overall, digestibility was similar between pasteurized and raw HMPC (degree of hydrolysis ranged from 26 to 34 %). Lactoferrin was more susceptible to gastric and intestinal digestion after thermal pasteurization. Additionally, the resistance of β-casein to digestion increased after HHP and Holder pasteurization due to aggregation and changes in protein structure. During intestinal digestion, Holder pasteurization induced a higher release of arginine, phenylalanine and tyrosine from HMPC compared to raw and HHP-treated HMPC. Overall, protein structural changes induced by human milk (HM) processing (freeze-thawing and filtration) and pasteurization treatments affected HMPC proteolysis during in vitro digestion. However, protein digestion behaviors were quite similar for raw and HHP-treated HMPC compared to the thermal-treated HMPC, with no effect on lactoferrin digestion. Consequently, pasteurization of HMPC by HHP represents an interesting non-thermal process that preserves the HM bioactive proteins during digestion.

Peripheral Amino Acid Appearance Is Lower Following Plant Protein Fibre Products, Compared to Whey Protein and Fibre Ingestion, in Healthy Older Adults despite Optimised Amino Acid Profile

Plant-based proteins are generally characterised by lower Indispensable Amino Acid (IAA) content, digestibility, and anabolic properties, compared to animal-based proteins. However, they are environmentally friendlier, and wider consumption is advocated. Older adults have higher dietary protein needs to prevent sarcopenia, a disease marked by an accelerated loss of muscle mass and function. Given the lower environmental footprint of plant-based proteins and the importance of optimising dietary protein quality among older adults, this paper aims to assess the net peripheral Amino Acid (AA) appearance after ingestion of three different plant protein and fibre (PPF) products, compared to whey protein with added fibre (WPF), in healthy older adults. In a randomised, single-blind, crossover design, nine healthy men and women aged ≥65 years consumed four test meals balanced in AA according to the FAO reference protein for humans, matched for leucine, to optimally stimulate muscle protein synthesis in older adults. A fasted blood sample was drawn at each visit before consuming the test meal, followed by postprandial arterialise blood sampling every 30 min for 3 h. The test meal was composed of a soup containing either WPF or PPF 1-3. The PPF blends comprised pea proteins with varying additional rice, pumpkin, soy, oat, and/or almond protein. PPF product ingestion resulted in a lower maximal increase of postprandial leucine concentration and the sum of branched-chain AA (BCAA) and IAA concentrations, compared to WPF, with no effect on their incremental area under the curve. Plasma methionine and cysteine, and to a lesser extent threonine, appearance were limited after consuming the PPF products, but not WPF. Despite equal leucine doses, the WPF induced greater postprandial insulin concentrations than the PPF products. In conclusion, the postprandial appearance of AA is highly dependent on the protein source in older adults, despite providing equivalent IAA levels and dietary fibre. Coupled with lower insulin concentrations, this could imply less anabolic potential. Further investigation is required to understand the applicability of plant-based proteins in healthy older adults.

Impact of Flaxseed Gums on the Colloidal Changes and In Vitro Digestibility of Milk Proteins

Flaxseed (Linum usitatissimum L.) mucilage is one of the most studied plant seed gums in terms of its techno-functional and health-promoting properties. Nonetheless, the interplay of flaxseed gum (FG) with other food biopolymers, such as milk proteins, under in vitro digestion conditions remains underexplored. The aim of the present work was to investigate the colloidal interplay between flaxseed gum (golden or brown) and milk proteins (sodium caseinate or whey protein isolate) under simulated in vitro digestion conditions and its relationship with the attained in vitro protein digestibility. The presence of flaxseed gum in the milk protein food models and in the oral food boluses obtained was associated with the occurrence of segregative microphase separation. Flaxseed gum exhibited a prominent role in controlling the acid-mediated protein aggregation phenomena, particularly in the sodium caseinate gastric chymes. The addition of FG in the food models was associated with a higher amount of intact total caseins and β-lactoglobulin at the end of the gastric processing step. Monitoring of the intestinal processing step revealed a very advanced cleavage of the whey proteins (>98%) and caseins (>90%). The degree of the milk protein hydrolysis achieved at the end of the intestinal processing was significantly higher in the systems containing flaxseed gum (i.e., 59−62%) than their gum-free protein counterparts (i.e., 46−47%). It was postulated that the electrostatic milk protein complexation capacity and, to a lesser extent, the thickening effect of flaxseed gum influenced the in vitro digestibility of the milk proteins.

Effect of in vitro gastrointestinal digestion on the antibacterial activity of bioactive dairy formulas supplemented with lactoferrin against Cronobacter sakazakii

Milk is a source of proteins with high nutritional value and relevant biological activities. Bioactive milk proteins, like lactoferrin, are important for newborn development and can also be used as ingredients in functional products to improve health. Lactoferrin is essential in infant’s diet, since protects against infections and promotes immune system maturation. Bovine lactoferrin is used to supplement formula milk in order to strengthen baby’s defences against some pathogenic bacteria. Thus, lactoferrin supplemented formula can be a barrier against emergent pathogens, such as Cronobacter sakazakii, which has caused great concern in the last few years. Milk proteins generate bioactive peptides in the digestion process, and it is known that industrial processing can modify their susceptibility to digestion. Treatments such as heating have been shown to denature whey proteins and make them more easily digestible. Therefore, the aim of this study was to analyze the effect of technological treatments and gastrointestinal digestion on the antibacterial activity against C. sakazakii of proteins present in dairy formulas supplemented with lactoferrin. Commercial bovine lactoferrin has been shown to have antibacterial activity against C. sakazakii, both in the native state and after static in vitro gastrointestinal digestion. In addition, the digests obtained from dairy formulas subjected to technological treatments, either homogenization or pasteurization, have higher antibacterial activity than non-treated formulas. The release of low molecular weight peptides during the in vitro gastric digestion is probably the cause that would explain the enhanced antibacterial activity of the digested dairy formulas.

Impact of alfalfa (Medicago sativa L.) galactomannan on the microstructural and physicochemical changes of milk proteins under static in-vitro digestion conditions

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The impact of alfalfa galactomannan (AAG) on the digestibility of milk proteins was studied.

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AAG mediated the intragastric aggregation of both sodium caseinate and whey protein isolate.

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AAG affected only the peptic cleavage of caseins and β-lactoglobulin in the gastric chymes.

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AAG enhanced the free amino acids release in the gastric chymes regardless of the protein type.

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The free amino acids release rate in the intestinal chymes were adversely related to AAG content.

This paper reports on the impact of alfalfa galactomannan (AAG, 0.1, 0.5 or 1% wt.) on the colloidal changes and digestibility of sodium caseinate (NaCN) and whey protein isolate (WPI) dispersions (10% wt.) under static in-vitro digestion conditions. Static laser light scattering and confocal laser scanning microscopy-assisted assessment of the NaCN-based gastric chymes confirmed the ability of AAG to control the acid-induced protein coagulation phenomena. Contrarily, the presence of AAG in the WPI-based gastric chymes was associated with the formation of larger aggregates due to the occurrence of segregative microphase separation. The kinetic modelling of the SDS-PAGE densitometric data showed that the intragastric peptic cleavage rates were higher for caseins than whey proteins (β-lactoglobulin, α-lactalbumin). However, free amino acid (FAA) release rates did not exceed 12% under intragastric conditions, whilst notably higher release rates were achieved in the intestinal digesta (36–52%). In all cases, the FAA release rates significantly increased in the presence of AAG.

Alternatives to Cow’s Milk-Based Infant Formulas in the Prevention and Management of Cow’s Milk Allergy

Cow’s milk-based infant formulas are the most common substitute to mother’s milk in infancy when breastfeeding is impossible or insufficient, as cow’s milk is a globally available source of mammalian proteins with high nutritional value. However, cow’s milk allergy (CMA) is the most prevalent type of food allergy among infants, affecting up to 3.8% of small children. Hypoallergenic infant formulas based on hydrolysed cow’s milk proteins are commercially available for the management of CMA. Yet, there is a growing demand for more options for infant feeding, both in general but especially for the prevention and management of CMA. Milk from other mammalian sources than the cow, such as goat, sheep, camel, donkey, and horse, has received some attention in the last decade due to the different protein composition profile and protein amino acid sequences, resulting in a potentially low cross-reactivity with cow’s milk proteins. Recently, proteins from plant sources, such as potato, lentil, chickpeas, quinoa, in addition to soy and rice, have gained increased interest due to their climate friendly and vegan status as well as potential lower allergenicity. In this review, we provide an overview of current and potential future infant formulas and their relevance in CMA prevention and management.

Analysis of the Factors Affecting Static In Vitro Pepsinolysis of Food Proteins

In this meta-analysis, we collected 58 publications spanning the last seven decades that reported static in vitro protein gastric digestion results. A number of descriptors of the pepsinolysis process were extracted, including protein type; pepsin activity and concentration; protein concentration; pH; additives; protein form (e.g., ‘native’, ‘emulsion’, ‘gel’, etc.); molecular weight of the protein; treatment; temperature; and half-times (HT) of protein digestion. After careful analysis and the application of statistical techniques and regression models, several general conclusions could be extracted from the data. The protein form to digest the fastest was ‘emulsion’. The rate of pepsinolysis in the emulsion was largely independent of the protein type, whereas the gastric digestion of the native protein in the solution was strongly dependent on the protein type. The pepsinolysis was shown to be strongly dependent on the structural components of the proteins digested—specifically, β-sheet-inhibited and amino acid, leucine, methionine, and proline-promoted digestion. Interestingly, we found that additives included in the digestion mix to alter protein hydrolysis had, in general, a negligible effect in comparison to the clear importance of the protein form or additional treatment. Overall, the findings allowed for the targeted creation of foods for fast or slow protein digestion, depending on the nutritional needs.

Comparison of conventional heat-treated and membrane filtered infant formula using an in vitro semi-dynamic digestion method

Introducing membrane filtration steps into infant milk formula (IMF) manufacture can partly preserve native whey proteins in the final products. In this study, IMF produced by membrane filtration (MEM-IMF) and...

Proteomics Analysis Reveals Altered Nutrients in the Whey Proteins of Dairy Cow Milk with Different Thermal Treatments

Thermal treatments of milk induce changes in the properties of milk whey proteins. The aim of this study was to investigate the specific changes related to nutrients in the whey proteins of dairy cow milk after pasteurization at 85 °C for 15 s or ultra-high temperature (UHT) at 135 °C for 15 s. A total of 223 whey proteins were confidently identified and quantified by TMT-based global discovery proteomics in this study. We found that UHT thermal treatment resulted in an increased abundance of 17 proteins, which appeared to show heat insensitivity. In contrast, 15 heat-sensitive proteins were decreased in abundance after UHT thermal treatment. Some of the heat-sensitive proteins were connected with the biological immune functionality, suggesting that UHT thermal treatment results in a partial loss of immune function in the whey proteins of dairy cow milk. The information reported here will considerably expand our knowledge about the degree of heat sensitivity in the whey proteins of dairy cow milk in response to different thermal treatments and offer a knowledge-based reference to aid in choosing dairy products. It is worth noting that the whey proteins (lactoperoxidase and lactoperoxidase) in milk that were significantly decreased by high heat treatment in a previous study (142 °C) showed no significant difference in the present study (135 °C). These results may imply that an appropriately reduced heating intensity of UHT retains the immunoactive proteins to the maximum extent possible.

The impact of thermal processing on the simulated infant gastrointestinal digestion, bactericidal and anti-inflammatory activity of bovine lactoferrin - An in vitro study

Lactoferrin (LF) is a multifunctional glycoprotein which, when thermally processed, undergoes significant physicochemical changes. The link between such changes and the bioactivity of LF is not well characterised and requires much research. In this work, bovine LF solutions (1%, w/v, protein, pH 7) were thermally processed using high temperature short time conditions (72, 80, 85 or 95 °C with 15 s holding times). Following this, it was shown that LF and heat induced LF aggregates were largely resistant to simulated infant gastric, but not intestinal, digestion. Also, the efficacy of LF bactericidal activity, and inhibition of lipopolysaccharide-induced NF-κB activation were negatively impacted by thermal processing. This study confirmed that the efficacy of LF bio-functionalities was affected by the extent of heat-induced changes in protein structure whereby processing conditions of least severity (i.e. pasteurisation) had the least impact on bioactivity.

Semi-industrial production of a minimally processed infant formula powder using membrane filtration

Infant formula (IF) is submitted to several heat treatments during production, which can lead to denaturation or aggregation of proteins and promote Maillard reaction. The objective of this study was to investigate innovative minimal processing routes for the production of first-age IF powder, thus ensuring microbial safety with minimal level of protein denaturation. Three nutritionally complete IF powders were produced at a semi-industrial scale based on ingredients obtained by fresh bovine milk microfiltration (0.8 and 0.1-µm pore size membranes). Low-temperature vacuum evaporation (50°C) and spray-drying (inlet and outlet temperatures of 160 and 70°C, respectively) were conducted to produce the T- formula with no additional heat treatment. The T+ formula was produced with a moderate heat treatment (75°C for 2 min) applied before spray-drying, whereas the T+++ formula received successive heat treatments (72°C for 30 s on the milk; 90°C for 2-3 s before evaporation; 85°C for 2 min before spray-drying), thus mimicking commercial powdered IF. Protein denaturation and Maillard reaction products were followed throughout the production steps and the physicochemical properties of the powders were characterized. The 3 IF powders presented satisfactory physical properties in terms of a_w, free fat content, glass transition temperature, and solubility index, as well as satisfactory bacteriological quality with a total flora <10³ cfu/g and an absence of pathogens when a high level of bacteriological quality of the ingredients was ensured. Protein denaturation occurred mostly during the heat treatments of T+ and T+++ and was limited during the spray-drying process. The IF powder produced without heat treatment (T-) presented a protein denaturation extent (6 ± 4%) significantly lower than that in T+++ (58 ± 0%), but not significantly different from that in T+ (10 ± 4%). Although T- tended to contain less Maillard reaction products than T+ and T+++, the Maillard reaction products did not significantly discriminate the infant formulas in the frame of this work. The present study demonstrated the feasibility of producing at a semi-industrial scale an infant formula being bacteriologically safe and containing a high content of native proteins. Application of a moderate heat treatment before spray-drying could further guarantee the microbiological quality of the IF powders while maintaining a low protein denaturation extent. This study opens up new avenues for the production of minimally processed IF powders.

Thermal or membrane processing for Infant Milk Formula: Effects on protein digestion and integrity of the intestinal barrier

Infant Milk Formula (IMF) is designed as a breastmilk substitute to satisfy the nutritional requirements during the first months of life. This study investigates the effects of two IMF processing technologies on cow milk protein digestion using an infant static in vitro gastrointestinal model. The degree of protein hydrolysis at the end of the gastric phase was 3.7-fold higher for IMF produced by high temperature (IMF-HT), compared to IMF produced by cascade membrane filtration (IMF-CMF), as assessed by free N-terminal group analysis. The processing type also influenced the panel of bioavailable peptides detected in basolateral compartments of Caco-2 monolayers exposed to gastrointestinal digested IMFs. In addition, IMF-CMF significantly increased tight junction protein, claudin 1, whilst IMF-HT significantly reduced tight junction integrity. In conclusion, producing IMF by CMF may preserve intestinal barrier integrity and can deliver its own unique inventory of bioavailable peptides with potential bioactivity.