In vitro fermentation potential of gut endogenous protein losses of growing pigs.

Fermentation of dietary and endogenous protein in the hindgut is generally considered detrimental to the health of pigs. We investigated the in vitro fermentation potential of porcine endogenous protein in ileal digesta and colonic mucus, using a N-free buffer with an excess of fermentable carbohydrates. Urea, whey protein isolate (WPI, positive control), WPI hydrolysate (WPIH), and combinations of the latter two were used to validate the assay. A new biphasic model, including a linear end simulation, fitted to the gas production data over a 48-h period identified the time point when substrate fermentation ended. A higher degree of hydrolysis of WPI resulted in a higher maximum gas production rate (Rmax, P < 0.01). Differences in Rmax and the time required to reach Rmax were observed among ileal digesta samples, with Rmax increasing with the insoluble protein content, and the highest Rmax occurring with colonic mucus samples (P < 0.05). The endogenous proteins entering the large intestine of pigs can ferment more rapidly compared to highly soluble and digestible protein sources, with Rmax positively correlated with decreasing solubility of endogenous nitrogenous components.

Protein fermentation in the hindgut of pigs can impact their health, affecting factors like growth rates and feed efficiency. Besides dietary protein, up to 50% of the protein entering the large intestine of growing pigs may be of endogenous origin. Therefore, we explored the fermentation potential of endogenous proteins compared to a well-known protein source, whey protein isolate (WPI). In developing and validating an in vitro gas production technique, we employed urea, WPI, WPI hydrolysate, and various combinations as substrates. The study introduces a new biphasic model for in vitro gas production, offering a detailed analysis of the fermentation process over a 48-h period. Our results revealed that porcine endogenous proteins can undergo rapid fermentation because the maximum gas production rate was higher compared to WPI. This insight is crucial for understanding the dynamics of protein fermentation in pigs. Additionally, we explored the solubility and molecular size of proteins, providing a comprehensive understanding of their fermentation characteristics. We found that endogenous proteins were less soluble compared to WPI but contained more smaller peptides. Unraveling the complexities of protein fermentation in pigs contributes to improvement of feed formulation for optimal gut health.

Exploring the midgut physiology of the non-haematophagous mosquito Toxorhynchites theobaldi.

Toxorhynchites mosquitoes have an exclusively phytophagous feeding habit as adults, which leads to significant differences in their morphophysiology compared with haematophagous mosquitoes. However, the molecular mechanisms of digestion in this mosquito are not well understood. In this study, RNA sequencing of the posterior midgut (PMG) of the mosquito Toxorhynchites theobaldi was undertaken, highlighting its significance in mosquito digestion. Subsequently, a comparison was made between the differential gene expression of the PMG and that of the anterior midgut. It was found that the most abundant proteases in the PMG were trypsin and chymotrypsin, and the level of gene expression for enzymes essential for digestion (such as serine protease, α-amylase and pancreatic triacylglycerol lipase) and innate immune response (including catalase, cecropin-A2 and superoxide dismutase) was like that of haematophagous mosquitoes. Peritrophin-1 was detected in the entire midgut, with an elevated expression level in the PMG. Based on our findings, it is hypothesized that a non-haematophagic habit might have been exhibited by the ancestor of Tx. theobaldi, and this trait may have been retained. This study represents a pioneering investigation at the molecular level of midgut contents in a non-haematophagous mosquito. The findings offer valuable insights into the evolutionary aspects of feeding habits in culicids.

Growth performance, nutrients digestibility, intestinal microbiota and histology altered in broilers fed maize- or sorghum-based diets.

This study aimed to evaluate the effect of varying levels of sorghum-based diets as an alternative to maize in broiler nutrition. A total of 320 one-day-old male Ross 708 broiler chickens were randomly allocated to four treatment groups (5 pens per treatment and 16 birds per pen), comprising a control group with a basal diet and groups receiving sorghum-based diets with 20%, 40%, and 100% maize replacement. The overall weight gain was significantly (p < 0.0001) higher in the control group, followed by 20%, 40%, and 100% sorghum replacement. Additionally, overall feed intake was significantly (p < 0.01) higher in the 20% sorghum replacement group compared to the control and other groups. Broilers fed sorghum-based diets exhibited a significantly (p < 0.01) increased feed conversion ratio. Carcass characteristics showed no significant differences between broilers fed corn and sorghum; however, the digestibility of crude protein and apparent metabolizable energy significantly (p < 0.01) increased in the 20% sorghum-corn replacement compared to the 40% and 100% replacement levels. Ileal villus height and width did not differ among the corn-sorghum-based diets, regardless of the replacement percentage. Furthermore, among the cecal microbiota, Lactobacillus count was significantly (p < 0.041) higher in the 20% corn-sorghum diet compared to the 40% and 100% replacement levels. These findings suggest that replacing corn up to 20% of corn with sorghum in broiler diet positively impact growth performance, gut health, nutrient digestibility, and cecal microbiota in broilers. However, larger replacements (40% and 100%) may have negative implications for broiler production and health.

Impact of replacing protein pellets with soybean grain on nutrient utilization and the rumen and blood parameters of feedlot cattle under tropical conditions.

The aim of this study was to explore the effect of replacing protein pellets with soybean grain in high-concentrate diets with or without the addition of silage, on the intake, digestibility, and rumen and blood parameters of feedlot cattle in tropical regions. Four cannulated, crossbred steers were used, 4.5 ± 0.5 years old, with an average weight of 685.55 ± 111.78 kg. The steers were distributed in a 4 × 4 Latin square, in a 2 × 2 factorial scheme (two sources of protein: protein pellets or whole soybean grain, with or without added dietary bulk). There was no effect (P ≥ 0.109) from the interaction between the source of protein and the addition of silage to the diet on dry matter (DM) and nutrient intake, or the digestibility (P ≥ 0.625) of DM or crude protein (CP). However, both factors affected (P ≤ 0.052) the intake of DM, neutral detergent fiber (NDF), and non-fiber carbohydrates (NFC), as well as the independent digestibility (P ≤ 0.099) of fat, NFC, total carbohydrates (TC), and total cholesterol concentration. There was an effect (P ≤ 0.053) from the interaction between the source of protein and the addition of silage to the diet on the digestibility of NDF and total digestible nutrients (TDN), as well as on the glycose concentration (P = 0.003). Blood parameters (i.e. protein, albumin, creatinine, triglycerides, aspartate aminotransferase (AST), and alanine aminotransferase (ALT)) were not affected (P ≥ 0.139) by the source of protein, the addition of silage, or their interaction. Lastly, including 150 g/kg silage DM in a high-grain diet, and using soybean grain as a source of protein in substitution of protein pellet could be a suitable nutritional strategy to ensure adequate DM and nutrient intake and digestibility, with no detrimental effects on rumen and blood parameters of feedlot cattle in the tropics.

Turmeric rhizomes reduced in vitro methane production and improved gas production and nutrient degradability.

The present study aimed to evaluate the effect of dry turmeric rhizomes on in vitro biogas production and diet fermentability. Turmeric rhizomes were included at gradually increased levels: 0, 0.5, 1, 1.5 and 2% of a diet containing per kg dr matter (DM): 500 g concentrate feed mixture, 400 g berseem hay and 100 g rice straw, and incubated for 48 h. Gas chromatography-mass spectrometry analysis showed that ar-turmerone, α-turmerone and ß-turmerone were the major bioactive compounds in the rhizomes. Turmeric rhizomes increased (p < 0.01) asymptotic gas production (GP) and rate and lag of CH4 production and decreased (p < 0.01) rate of GP, lag of GP, asymptotic CH4 production and proportion of CH4 production. Turmeric rhizome administration linearly increased (p < 0.01) DM and fiber degradability and concentrations of total short-chain fatty acids, acetic and propionic acids and ammonia-N and quadratically (p < 0.05) decreased fermentation pH. It is concluded that including up to 2% turmeric rhizomes improved in vitro ruminal fermentation and decreased CH4 production.

The role of olive leaves and saccharomyces cerevisiae supplementation in enhancing the performance and economic feasibility of fattening lambs.

Objectives were to assess the use of olive leaves (OL) to replace wheat straw, the forage source, and the supplementation of Saccharomyces cerevisiae (SC) on nutritional intake, growth performance, blood parameters, and carcass quality in lambs. A total of twenty-one newly weaned Awassi lambs, weighing an average of 19 ± 0.6 kg, were randomly distributed to three groups. These three diets were: CON: 0% OL control diet; OL diet of 25%; and OL plus 0.4 g SC/head/d (OLSC) diet of 25% of dietary dry matter (DM). The first seven days were devoted to adaptation and the next sixty days were devoted to gathering data. Daily records of nutrient intake were made. On the 49th day of data collection, four animals were randomly selected from each group and kept in individual metabolism cages (1.0 × 0.8 m) with slatted mash for eight days (four days for data collection and four days for cage adaptation) to evaluate N balance and nutrient digestibility. All lambs were slaughtered after the study to assess the quality of the meat and the carcass features. No difference in DM consumption (P > 0.05) between the treatment groups. When OL-containing diets were compared to the CON diet, the consumption of acid detergent fiber and neutral detergent fiber (NDF) was lower (P ≤ 0.0002), whereas metabolizable energy and ether extract were higher (P < 0.0001). While the OL diet was intermediate, the final BW, total gain, and average daily gain for the OLSC diet tended to be higher (P < 0.087) than the CON diet. Lambs fed the OL-containing diets had a lower (P = 0.0020) cost of growth ($US/kg) than lambs in the CON group. All other nutrient digestibilities were comparable between the treatment diets, except NDF digestibility, which was greater (P = 0.045) in the OLSC group than in the CON group. The N balance variables showed a similarity between the various diets (P > 0.05). Lambs fed the OLSC diet tended to have higher weights (P ≤ 0.098) for fasting live weight, hot carcass weight, carcass cuts weights, and cold carcass weight than lambs on the CON diet. The OLSC diet resulted in higher (P < 0.025) loin weight and intermuscular fat in comparison to the CON and OL diets. No difference (P ≥ 0.05) in the dissected tissues between diets. The longissimus dorsi muscle's dimensions and physicochemical characteristics did not alter (P > 0.05) across the treatment diets. In comparison to the CON and OL diets, the OLSC diet resulted in higher serum glucose levels (P = 0.044). Nonetheless, there were similarities (P ≥ 0.05) in various serum blood parameters between the treatment diets. In conclusion, using OL or/and supplemented SC is positively associated with nutrient intake, growth performance, some carcass parameters, and loin cut tissue, and the most effective aspect is decreasing production cost ($US/kg gain), which makes it a good solution to pass inflation feedstuff prices and cover animal needs.

Differential Effects of In Vitro Simulated Digestion on Antioxidant Activity and Bioaccessibility of Phenolic Compounds in Purple Rice Bran Extracts.

Pigmented rice varieties are abundant in phenolic compounds. Antioxidant activity and bioaccessibility of phenolic compounds are modified in the gastrointestinal tract. After in vitro simulated digestion, changes in antioxidant activity and bioaccessibility of phenolic compounds (phenolic acids, flavonoids, and anthocyanins) in purple rice brans (Hom Nil and Riceberry) were compared with undigested crude extracts. The digestion method was conducted following the INFOGEST protocol. Antioxidant activity was determined using the ferric-reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assays. The bioaccessibility index (BI) was calculated from the ratio of digested to undigested soluble phenolic content. Overall results showed that the in vitro simulated digested rice brans had lower antioxidant activity and lower total phenolic, flavonoid, and anthocyanin contents. However, the concentration of sinapic acid was stable, while other phenolic acids (gallic, protocatechuic, vanillic, ρ-coumaric, and ferulic acids) degraded after the oral, gastric, and intestinal phases. The BI of sinapic, gallic, vanillic, and ferulic acids remained stable, and the BI of quercetin was resistant to digestion. Conversely, anthocyanins degraded during the intestinal phase. In conclusion, selective phenolic compounds are lost along the gastrointestinal tract, suggesting that controlled food delivery is of further interest.

Human Milk Protein-Derived Bioactive Peptides from In Vitro-Digested Colostrum Exert Antimicrobial Activities against Common Neonatal Pathogens.

Human milk reduces risk for necrotizing enterocolitis in preterm infants. Necrotizing enterocolitis occurs in the ileocecal region where thousands of milk protein-derived peptides have been released from digestion. Digestion-released peptides may exert bioactivity, such as antimicrobial and immunomodulatory activities, in the gut. In this study, we applied mass spectrometry-based peptidomics to characterize peptides present in colostrum before and after in vitro digestion. Sequence-based computational modeling was applied to predict peptides with antimicrobial activity. We identified more peptides in undigested samples, yet the abundances were much higher in the digested samples. Heatmapping demonstrated highly different peptide profiles between undigested and digested samples. Four peptides (αS1-casein [157-163], αS1-casein [157-165], ß-casein [153-159] and plasminogen [591-597]) were selected, synthesized and tested against common pathogenic bacteria associated with necrotizing enterocolitis. All four exhibited bacteriostatic, though not bactericidal, activities against Klebsiella aerogenes, Citrobacter freundii and Serratia marcescens, but not Escherichia coli.

Human Oral Phase Coupled with In Vitro Dynamic Gastrointestinal Digestion for Assessment of Plant Sterol Bioaccessibility from Wholemeal Rye Bread.

A dynamic gastrointestinal digestion system (simgi) after a human oral phase was used, for the first time, to assess the bioaccessibility of plant sterols (PS) from wholemeal rye bread (74.8 ± 2.2 mg of PS/100 g d.m.) and PS-enriched wholemeal rye bread (PS-WRB) (1.6 ± 0.04 g of PS/100 g of fresh bread). The use of these solid food matrices requires a novel adaptation of the gastric phase of the system. The PS identified in the breads are campesterol, campestanol, stigmasterol, ß-sitosterol, sitostanol, Δ5-avenasterol, Δ5,24-stigmastadienol, Δ7-stigmastenol, and Δ7-avenasterol. The bioaccessibility of the total PS, only quantifiable in PS-WRB, is 19.9%, with Δ7-avenasterol being the most bioaccessible and Δ5-avenasterol being the least (p < 0.05). As shown in this study, PS-WRB can be considered to be a good choice to include in the daily diet. Furthermore, although the use of dynamic digestion methods for evaluating bioaccessibility implies high costs and technical complexity, their application means a closer approximation to in vivo scenarios.

Protein quality of a small mammal prey and its body organs for felids.

This study evaluated the protein quality of small mammalian prey and its body organs by analyzing amino acid (AA) composition and digestibility of wild adult rats and their body organs (skin/fur, bone, muscle, intestine, liver, kidney, spleen, brain, heart, and lung) utilizing an in vitro digestion method. The average dry matter (DM) digestibility of whole rats was 89.9%. The digestibility of total AA (TAA), total indispensable AA (TIAA), and total dispensable AA (TDAA) in whole rats was 85.6, 87.0, and 87.6%, respectively. Differences in DM digestibility were observed among rat organs, ranging from 59.0% in bone to 99.8% in muscle (P < 0.001). Highly digestible organs generally exhibited AA digestibility exceeding 90%, except for cysteine (Cys) in the intestine and kidney (83.8% and 88.9%, respectively). The digestibility of AAs in skin/fur ranged from 19.7% for Cys to 81.0% for glycine (Gly). In bone, the digestibility spanned from 56.9% for Gly to 81.1% for tyrosine (Tyr). Additionally, examining the digestible indispensable AA score (DIAAS) gives us an idea of the protein quality of small mammalian prey and their body organs. Our results complement information on AA supply and digestion during prey ingestion by felids.

As obligate carnivores, free-ranging felids consume prey and rely on nutrients from animal organs. Studies in adult carnivores such as domestic cats have demonstrated the importance of the dietary amino acid profile. Therefore, this research used rats as a small prey model to analyze the amino acid composition and digestibility of whole prey and its body organs through in vitro digestion methods. Our results add information on amino acid supply and digestion during natural food intake in felids.

Effect of harvesting strategy of second-cut orchardgrass silage on feed intake, digestion, and milk production in dairy cows.

We investigated the effects of regrowth interval and first-cut timing on the dietary characteristics of second-cut orchardgrass silage and feed intake and milk production in dairy cows fed second-cut orchardgrass silage. The second-cut grasses were harvested 7w after the first-cut at the early stage (E7w) or at the heading stage (H7w), or harvested 6w after the first-cut at the early stage (E6w) from orchardgrass sward, and then ensiled. We evaluated the effect of regrowth interval by comparing E7w and E6w, and the effect of first-cut timing by comparing E7w and H7w. Six multiparous Holstein cows were used in a replicated 3 × 3 Latin square design, with three dietary treatments: diets containing E7w, E6w, or H7w silage at 30% dietary dry matter. We observed that feeding E6w silage instead of E7w silage increased fiber digestibility, dry matter intake, and milk production; however, the first-cut timing (E7w vs. H7w) did not affect nutrient content and digestibility, feed intake, or lactation performance. These results show that harvesting at short regrowth intervals for second-cut orchardgrass can be an effective strategy for improving feed utilization and milk yield; however, the first-cut timing for second-cut orchardgrass has little impact.

Microalgae protein digestibility: How to crack open the black box?

Microalgae are booming as a sustainable protein source for human nutrition and animal feed. Nevertheless, certain strains were reported to have robust cell walls limiting protein digestibility. There are several disruption approaches to break down the cell integrity and increase digestive enzyme accessibility. This review's intent is to discuss the digestibility of microalgae proteins in intact cells and after their disruption. In intact single cells, the extent of protein digestibility is chiefly related to cell wall structural properties (differing among strains) as well as digestion method and when added to food or feed protein digestibility changes depending on the matrix's composition. The degree of effectiveness of the disruption method varies among studies, and it is complicated to compare them due to variabilities in digestibility models, strains, disruption method/conditions and their consequent impact on the microalgae cell structure. More exhaustive studies are still required to fill knowledge gaps on the structure of microalgal cell walls and to find efficient and cost-effective disruption technologies to increase proteins availability without hindering their quality.

Three nonconventional starch: Comparison of physicochemical properties and in vitro digestibility.

Extraction of starch from waste is also an effective way to recover resources and provide new sources of starch. In this study, starch was isolated from white kidney bean residue, chickpea residue, and tiger nut meal after protein or oil extraction, and the morphology of starch particles was observed to determine their physicochemical properties and in vitro digestibility. All these isolated starches had unique properties, among which white kidney bean starch (KBS) had a high amylose content (43.48%), and its structure was better ordered. Scanning electron microscopy revealed distinct granular morphologies for the three starches. KBS and chickpea starch (CHS) were medium-granular starches, whereas tiger nut starch was a small granular starch. Fourier transform infrared spectroscopy analysis confirmed the absence of significant differences in functional groups and chemical bonds among the three starch molecules. In vitro digestibility studies showed that CHS is more resistant to enzymatic degradation. Overall, these results will facilitate the development of products based on the separation of nonconventional starches from waste.

Neuropeptide Y receptor Y8b (npy8br) regulates feeding and digestion in Japanese medaka (Oryzias latipes) larvae: evidence from gene knockout. / 神经肽受体Y8b（npy8br）调节日本青鳉（Oryzias latipes）仔鱼的摄食和消化： æ¥è‡ªåŸºå› æ•²é™¤çš„è¯æ®.

Neuropeptide Y receptor Y8 (NPY8R) is a fish-specific receptor with two subtypes, NPY8AR and NPY8BR. Changes in expression levels during physiological processes or in vivo regulation after ventricular injection suggest that NPY8BR plays an important role in feeding regulation; this has been found in only a few fish, at present. In order to better understand the physiological function of npy8br, especially in digestion, we used clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) technology to generate npy8br-/- Japanese medaka (Oryzias latipes). We found that the deletion of npy8br in medaka larvae affected their feeding and digestion ability, ultimately affecting their growth. Specifically, npy8br deficiency in medaka larvae resulted in decreased feed intake and decreased expression levels of orexigenic genes (npy and agrp). npy8br-/- medaka larvae fed for 10 d (10th day of feeding) still had incompletely digested brine shrimp (Artemia nauplii) in the digestive tract 8 h after feeding, the messenger RNA (mRNA) expression levels of digestion-related genes (amy, lpl, ctra, and ctrb) were significantly decreased, and the activity of amylase, trypsin, and lipase also significantly decreased. The deletion of npy8br in medaka larvae inhibited the growth and significantly decreased the expression of growth-related genes (gh and igf1). Hematoxylin and eosin (H&E) sections of intestinal tissue showed that npy8br-/- medaka larvae had damaged intestine, thinned intestinal wall, and shortened intestinal villi. So far, this is the first npy8br gene knockout model established in fish and the first demonstration that npy8br plays an important role in digestion.

Bioaccessibility of Glucosylceramide in Rice Based on the Cooking Condition and Cultivar.

Glucosylceramide (GlcCer), a major sphingolipid in plants, possesses various food functions, including improvement of intestinal impairments. This study evaluated rice cooking conditions and cultivars based on GlcCer levels transferred into the digestive juice using an in vitro digestion model to investigate the factors related to GlcCer availability. GlcCer levels transferred into the digestive juice were higher in rice gruel than in boiled rice. The GlcCer levels in the digestive juice of boiled rice varied based on the rice cultivar, whereas those in rice gruel had no difference. Thus, GlcCer in rice was not fully utilized via digestion. Further, bioaccessibility was related to the amylose ratio and added water content.

Microencapsulation of lemongrass and mangosteen peel as phytogenic compounds to gas kinetics, fermentation, degradability, methane production, and microbial population using in vitro gas technique.

The purpose of the current study was to evaluate the impact of various doses of microencapsulated lemongrass and mangosteen peel (MELM) on gas dynamics, rumen fermentation, degradability, methane production, and microbial population in in vitro gas experiments. With five levels of microencapsulated-phytonutrient supplementation at 0, 1, 2, 3, and 4% of substrate, 0.5 g of roughage, and a concentrate ratio of 60:40, the trial was set up as a completely randomized design. Under investigation, the amount of final asymptotic gas volume was corresponding responded to completely digested substrate (b) increased cubically as a result of the addition of MELM (P < 0.01) and a cubic rise in cumulative gas output. The amount of MELM form did not change the pH and NH3-N concentration of the rumen after 12 and 24 h of incubation. However, methane production during 24 h of incubation, the levels were cubically decreased with further doses of MELM (P < 0.01) at 12 h of incubation. Increasing the dosage of MELM supplementation at 2% DM resulted in a significant increase in the digestibility of in vitro neutral detergent fiber (IVNDF) and in vitro true digestibility (IVTD) at various incubation times (P < 0.05), but decreased above 3% DM supplementations. Moreover, the concentration of propionic acid (C3) exhibited the variations across the different levels of MELM (P < 0.05), with the maximum concentration obtained at 2% DM. The populations of Fibrobacter succinogenes, Ruminococcus albus, Ruminococcus flavefaciens, and Megasphaera elsdenii revealed a significant increase (P < 0.05), while the quantity of Methanobacteriales decreased linearly with increasing doses of MELM. In conclusion, the inclusion of MELM at a concentration of 2% DM in the substrate which could enhance cumulative gas production, NDF and true digestibility, C3 production, and microbial population, while reducing methane concentration and Methanobacterial abundance.

Aggregation structure induced by heat treatments mediated the gastric digestion behavior of soybean protein.

The common belief that heat treatment enhances the gastric digestion of proteins is largely based on findings from animal proteins and may not apply to all proteins, particularly plant proteins. Here, we compared the digestion characteristics of soybean protein isolates (SPI) in an in vitro semi-dynamic digestion model and found distinct effects of heat treatment on the digestion properties of plant proteins. The results revealed that heat-treated SPIs formed clots during the early stages of digestion, although the clots gradually became smaller and looser as digestion progressed, the systems remained turbid at the end of gastric digestion, indicating the lag in their emptying. Furthermore, heat treatment altered the rheological properties of SPI, resulting in increased viscosity and slower gastric emptying. These effects became more pronounced with increasing heat treatment temperatures. The fluorescence spectrum analysis indicated that heat treatment altered its conformation. This led to protein unfolding and exposure of hydrophobic groups, facilitating the formation of larger aggregates during digestion. Additionally, heat treatment exposed more cleavage sites for gastric proteases, increasing the extent of hydrolysis. Elevated levels of free amino acids and a smaller molecular weight distribution further corroborated these findings. These findings contribute to a deeper understanding of the gastric digestion characteristics of plant proteins and the relationship between protein aggregation structure and the digestion process.

Role of particle size in modulating starch digestibility and textural properties in a rye bread model system.

In cereal products, the use of flour containing clusters of intact cells has been indicated as a potential strategy to decrease starch digestion. Rye possesses more uniform and thicker cell walls than wheat but its protective effect against starch digestion has not been elucidated. In this study, rye flours with three different particle sizes, large (LF) (∼1700 µm), medium (MF) (∼1200 µm), and small (SF) (∼350 µm), were used to produce model bread. The textural properties of these breads were analysed using Textural Profile Analysis (TPA). The starch digestibility of both the flour and the bread was measured using Englyst's method, while the presence of intact cell clusters was examined using Confocal Laser Scanning Microscopy (CLSM). Additionally, the disintegration of bread digesta during simulated digestion was assessed through image analysis. CLSM micrographs revealed that bread made with MF and LF retained clusters of intact cells after processing, whereas bread made with SF showed damaged cell walls. Starch digestibility in LF and MF was lower (p ≤ 0.05) than that in SF. Bread produced with MF and LF exhibited the least (p ≤ 0.05) cohesive and resilient texture, disintegrated more during digestion, and exhibited higher starch digestibility (p ≤ 0.05) than bread made with SF. These results highlight the central role of bread texture on in vitro starch digestibility.

Release profile of amino acids encapsulated in solid lipid particles during in vitro oro-gastrointestinal digestion.

Some amino acids are known to mediate immune responses through gut microbiota metabolism in both humans and monogastric animals. However, through the diet, most free amino acids are absorbed in the small intestine and only a small quantity reaches the microbiota-rich colon. To enhance microbial metabolism of amino acids and their potential health benefits, encapsulation strategies are developed for their protection and delivery to the colon. So far, the main encapsulation systems for amino acids are based on solid lipid particles, but their fate within the digestive tract has never been fully clarified. In this study, we investigated the release of various amino acids (branched-chain amino acid mixture, or lysine, or tryptophan) loaded in solid lipid particles during in vitro oro-gastrointestinal digestion mimicking the piglet. The loaded solid lipid particles were fully characterized for their composition, thermal behavior, molecular structure, crystalline state, surface morphology, and particle size distribution. Moreover, we investigated the effect of particle size by sieving solid lipid particles into two non-overlapping size fractions. We found that amino acid release was high during the gastric phase of digestion, mainly controlled by physical parameters, namely particle size and crystalline state including surface morphology. Large particle size and/or smooth ordered particle indeed led to slower and lower release. Although lipid hydrolysis was significant during the intestinal phase of digestion, the impact of the crystalline state and surface morphology was also observed in the absence of enzymes, pointing to a dominant water/solute diffusion mechanism through these porous solid lipid particles.

Assessment of protein and phospholipid bioaccessibility in ultrafiltered buttermilk cheese using TIM-1 in vitro gastrointestinal methods.

To meet the high consumer demand, butter production has increased over the last few years. As a result, the buttermilk (BM) co-produced volumes require new ways of adding value, such as in cheese manufacturing. However, BM use in cheese milk negatively influences the cheesemaking process (e.g., altered coagulation properties) and the product's final quality (e.g., high moisture content). The concentration of BM by ultrafiltration (UF) could potentially facilitate its use in cheese manufacturing through an increased protein content while maintaining the milk salt balance. Simultaneously, little is known about the digestion of UF BM cheese. Therefore, this study aimed to characterize the impact of UF BM on cheese manufacture, its structure, and its behavior during in vitro digestion. A 2-fold UF concentrated BM was used for cheese manufacture (skim milk [SM] - control). Compositional, textural, and microstructural analyses of cheeses were first conducted. In a second step, the cheeses were fed into an in vitro TNO gastrointestinal digestion model (TIM-1) of the stomach and small intestine and protein and phospholipid (PL) bioaccessibility was studied. The results showed that UF BM cheese significantly differed from SM cheese regarding its composition, hardness (p < 0.05) and microstructure. However, in TIM-1, UF BM and SM cheeses showed similar digestion behavior as a percentage of protein and PL intake. Despite relatively more non-digested and non-absorbed PL in the ileum efflux of UF BM cheese, the initially higher PL concentration contributes to an enhanced nutritional value compared to SM cheese. To our knowledge, this study is the first to compare the bioaccessibility of proteins and PL from UF BM and SM cheeses.