Gastric Phase Research Articles

Low-intensity pulsed electric field processing prior to germination improves in vitro digestibility of faba bean (Vicia faba L.) flour and its derived products: A case study on legume-enriched wheat bread

This study investigated the effect of low-intensity pulsed electric field (PEF) (0.3–0.7 kV/cm) and/or germination (0–72 h, 20 °C) on faba beans prior to flour- and breadmaking. PEF (0.5 and 0.7 kV/cm) had no significant effect on the germination performance of faba bean but had a positive effect on in vitro starch and protein hydrolysis of PEF-treated beans germinated for 72 h. The incorporation of flour from soaked, germinated, PEF-treated, and PEF-treated+germinated faba beans into wheat bread, at 30% mass level, improved the nutritional composition (total starch and protein contents) and protein digestibility but it reduced the specific volume and increased the density, brownness, and hardness of the bread. This finding shows for the first time that PEF-treatment (<0.7 kV/cm) of faba beans followed by germination (72 h) improved in vitro starch and protein hydrolysis of its flour and the protein digestibility at gastric phase of its enriched wheat bread.

In vitro digestibility and solubility of phosphorus of three plant-based meat analogues.

Interest in plant-based meat analogues has increased and can be expected to be applied to pet foods, which necessitates the understanding of the nutrient supply in those foods. Our primary aim was to advance our understanding of the digestive properties of sterilized plant-based meat analogues. The impact of the preparatory processing steps on the solubility of meat analogues was studied. Meat analogues were made by mixing water, salt, and wheat gluten with soy protein isolate, pea protein isolate, or faba bean concentrate. Mixed materials were processed into model meat analogues using shear cell technology. Products were canned in water or gravy and sterilized. An animal-based canned pet food was made as a reference. Products sampled at the processing steps (mixing, shearing, sterilization) were digested in vitro. Samples of digestate were taken at the gastric phase (0 and 120 min) and small intestinal phase (120, 200, 280, and 360 min) for analysis of protein hydrolysis. The extent digestion of nitrogen and dry matter was determined at the end of incubation. Total phosphorus, soluble phosphorus after acid treatment, and after acid and enzymatic treatment were determined. The degree of hydrolysis after gastric digestion was low but increased immediately in the small intestinal phase; products based on pea had the highest values (56%). Nitrogen digestibility was above 90% for all materials at each processing step, indicating that bioactive compounds were absent or inactivated in the protein isolates and concentrate. Phytate seemed to play a minor role in meat analogues, but phosphorus solubility was influenced by processing. Shearing decreased soluble phosphorus, but this effect was partly reversed by sterilization. Nutrient digestibility as well as phosphorus solubility in plant-based products was higher than or comparable with the reference pet food. These findings show that the digestive properties of the tested plant-based meat analogues do not limit the supply of amino acids and phosphorus.

Self‐assembling bioactive peptides for gastrointestinal delivery—Bioinformatics‐driven discovery and in vitro assessment

SummaryFood‐derived peptides are promising materials for oral delivery purposes as they are readily available, can be generated using common techniques, and their self‐assembly properties can be tuned for specific applications. A method for identifying such self‐assembling bioactive peptides (SABP) candidates based on in silico analysis was developed and allowed for the discovery of a bovine‐derived SABP: FFVAPFPEVFGK. This peptide was then successfully generated from the αs1‐casein using enzymatic hydrolysis and isolated with size exclusion chromatography. Furthermore, we assessed the in vitro potential of the peptide for oral delivery to the lower gastrointestinal tract, using the INFOGEST standardised protocol. Transmission electron microscopy and mass spectrometry analyses showed that both the natural and the synthetic peptide were able to resist degradation in the oral and gastric phases. Indeed, the peptides remained assembled at the end of the gastric phase with some of the structure eroded from the action of pepsin and/or the pH. This article provides further insight into the potential of food‐derived peptides as functional food ingredients for oral delivery.

Human Norovirus Surrogate Is Highly Stable in Berry Smoothies and under In Vitro Simulated Digestion.

Human noroviruses are major causes of foodborne outbreaks linked to berries. The overall goal of this study was to investigate the persistence of a human norovirus surrogate, Tulane virus (TV), in berry smoothies and under simulated digestion through the gastrointestinal track. Two types of smoothies were prepared from blueberries and strawberries. Tulane virus was spiked into each smoothie and incubated either at 37 or 4 °C for 2, 60, and 120 min. Furthermore, the virus-spiked smoothies were subjected to sequential oral (2 min), gastric (10 and 60 min), and intestinal (15 and 120 min) digestion according to the standardized INFOGEST model. Quantification of infectious TV was carried out using the TCID50 assay. At 4 °C, in both berry smoothies, TV infectivity did not show significant changes throughout the 120 min period. At 37 °C, TV infectivity showed significant reduction (~0.5 log TCID50/mL) only in blueberry smoothies starting at 60 min. During the oral, gastric, and intestinal digestion phases, the mean log reduction in TV infectivity in blueberry did not exceed ~0.5 log, while infectious TV in strawberry smoothies under all phases was stable. Given the notable stability of infectious viruses in berry smoothies and the gastrointestinal tract, prevention of norovirus contamination of berries is paramount to reduce virus outbreaks linked to berries.

Effect of high-hydrostatic pressure on the digestibility of egg yolk and granule.

The impact of high hydrostatic pressure (HHP) on protein digestibility of egg yolk and egg yolk granule was evaluated by static in vitro digestion using the standardized INFOGEST 2.0 method. The degree of hydrolysis (DH) and the phospholipid content were determined during digestion, and the protein and peptide profiles were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and reverse phase-high pressure liquid chromatography (RP-HPLC). The results showed that HHP induced protein aggregation in egg yolk and granule, mainly by disulfide bridges, which were not disrupted in the oral phase. Proteolysis during the gastric phase improved egg yolk and granule protein solubility, regardless of whether HHP was applied. However, the extent of the samples' digestibility was not affected, with DH values ranging from 15% to 20%. During the intestinal phase, the DH of egg yolk protein (∼40%) was higher than that of the granule (∼25%), probably due to the denser structure of the granule reducing the accessibility of intestinal enzymes. The DH, peptide, and protein profiles of control and HHP-treated egg yolk showed similar protein digestion behaviors for both gastric and intestinal phases. Among the different proteins, only the digestibility of β-phosvitin in HHP-treated granule was enhanced. Consequently, applying HHP to granules represents an interesting process that improves the digestibility of phosvitin with the potential to generate bioactive phosvitin-derived phosphopeptides. PRACTICAL APPLICATION: High hydrostatic pressure, mainly used as a preservation process, did not impair the nutritional quality of the egg yolk and granule proteins but improved the susceptibility of phosvitin (protein contained in egg yolk) proteolysis to produce bioactive phosphopeptides. Consequently, applying HHP to granules represents an interesting process that improves the digestibility of phosvitin.

Digestive properties of β-CN and α-La in different milk protein ingredients

The digestion behavior of proteins not only differs between protein types but also between ion saturation and protein profile. This study aimed to investigate the digestive properties of α-La and β-CN in different dairy protein ingredients, including β-CN concentrate (βCC), micellar casein concentrate (MCC), α-La concentrate (α-LaC), and whey protein concentrate (WPC80), using an in-vitro infant static digestion model. α-La digested much faster in WPC than in α-LaC in the gastric phase, whereas β-CN digested faster in βCC than in MCC during gastric digestion. In the intestinal phase, α-La released more amino acids than β-CN. The released essential amino acids index (EAAIS) was higher in α-LaC than WPC80 and higher in βCC than MCC. This study facilitates better understanding of the effect of protein profile, protein structure, and calcium binding on the digestion behavior of β-CN and α-La, which provide reference for selection of dairy ingredient for infant formula.

Proteolysis of lactoferrin and β-casein in complex coacervate and uncomplexed forms during in vitro infant gastrointestinal digestion

Lactoferrin is of interest for infant nutrition due to its roles in supporting gastrointestinal development. When supplemented orally, digestive exposure may reduce the availability and biofunctionality of the protein and its derived peptides. The aim of this study was to evaluate the proteolysis of bovine lactoferrin and β-casein coacervates following infant in vitro digestion. Coacervation of β-casein with lactoferrin showed a protective function against peptic proteolysis, increasing the levels of intact β-casein and lactoferrin during gastric digestion, while the uncomplexed β-casein was readily proteolyzed. The coacervate was shown to protect the C-terminal of β-casein against gastric proteolysis. This resulted in altered peptide profiles in the gastric and intestinal phases, requiring additional research to ascertain potential implications for biological activity. This study demonstrates the impact of protein–protein interactions on proteolysis during digestion, which may delay proteolysis and possibly protect the bioactive properties of the proteins.

Metabolic changes and isoflavone biotransformation in natto for improved nutritional distribution and bioavailability

We used LC-MS to identify the metabolic changes in soybean fermented by Bacillus subtilis DC-15 to comprehend the biochemical alterations. Total 650 distinct metabolites were observed, with amino acids, dipeptides, fatty acids, small molecule sugars, and isoflavones having the largest abundances. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the primary metabolic pathways involved during the fermentation of soybeans were related to amino acid metabolism, including beta-alanine metabolism, phenylalanine metabolism, glycine, serine, and threonine metabolism. In the gastric phase, the maximum amount of soy isoflavones was successfully converted from its glycoside form (50.04 μg/mL) to the aglycone form (104.07 μg/mL). The distribution of protein and lipid particles in natto during various stages of digestion showed changes from aggregated particles to more scattered particles. For the future development and enhancement of fermented soybean products, our metabolomic data can shed light on activated biochemical pathways and changes in metabolic pattern.

Semi-dynamic in vitro digestion of sourdough bread enriched with flaxseed oil coacervates

Food structure and addition of encapsulated compounds can impact the gastro-intestinal digestion of food. Flaxseed oil was encapsulated by complex coacervation using soluble pea protein and gum arabic as shell materials, dried by either spray or electrostatic spray drying and incorporated into sourdough dough before baking. Three bread formulations were prepared using spray-dried (B-SD), electrospray-dried coacervates (B-ES) and free ingredients used in the encapsulation (B). The standardised semi-dynamic INFOGEST in vitro digestion method was used. Cumulated protein/free NH2 release and cumulated free fatty acids (FFA) release were used to assess protein and lipid digestion. Coacervates were resistant to bread preparation since they were visible in B-SD and B-ES. The total release of protein, free NH2 and FFA by the end of intestinal digestions ranged between 41.58–45.23%, 1.08–1.22 µmol/g protein and 22.26–63.54%, respectively. There were no significant differences between formulations. There was a statistically significant increase (p < 0.5) of about three times in FFA release between the oral and gastric phases. Our findings help to understand the behaviour of coacervates when incorporated into solid food. In this study, the delivery structures did not affect in vitro digestion and may be used to increase the polyunsaturated fatty acid content by 50%.

Can arsenic bioavailability be predicted in soils using in vitro gastro-intestinal simulation?

Many gastrointestinal simulation methods have been used to predict bioavailability, but the suitability of different methods for the same metal(loid)s varies widely, which inevitably affects the accuracy of human health risk assessment. Arsenic is a common and important contaminant in many contaminated land situations. It can be readily absorbed and has teratogenic and mutagenic toxicity. Therefore, in this study, four the most commonly used in vitro simulation methods (the Physiologically Based Extraction Test (PBET), In Vitro Gastrointestinal Method (IVG), Soluble Bioavailability Research Consortium (SBRC), the Unified BARGE Method (UBM)) were tested against an in vivo animal live model, to evaluate their effectiveness for the prediction of soil As bioavailability in 10 industrially contaminated soils. The soil As relative bioavailability (RBA) varied between 15% and 68% in the different soils. As bioaccessibility differed between the 4 gastro-intestinal simulation methods. Gastric phase of UBM (UBMG) predicted As relative bioavailability the best of the 4 assays (R2 = 0.81). This study provides theoretical and technical support to refine human health risk assessment of As in soils from urban industrial legacy contaminated sites.

The acute effect of a β-glucan-enriched oat bread on gastric emptying, GLP-1 response, and postprandialglycaemia and insulinemia: a randomised crossover trial in healthy adults.

The cereal fibre β-glucan reduces postprandial glycaemia, however, the underlying mechanisms are not fully understood. Thus, the aim of this study was to investigate the acute effect of a β-glucan-enriched oat bread on gastric emptying half-time (T1/2), gastric emptying lag phase (Tlag), and gastric emptying rate (GER), and the secretion of glucagon-like peptide-1 (GLP-1) as potential means to influence postprandial glycaemia. A randomised crossover trial was conducted in 22 healthy adults (age 24.6 ± 3.1years, BMI 23.1 ± 2.7kg/m2) receiving 25g available carbohydrates from a β-glucan-enriched oat bread or a control whole-wheat bread at two non-consecutive days. T1/2, Tlag, and GER were determined based on ultrasound measures of the cross-sectional gastric antrum area in the fasting state and 15, 30, 45, 60, 90, and 120min postprandially. Capillary glucose, serum insulin, and plasma GLP-1 concentrations were measured at the same time points. A biphasic pattern of gastric emptying with a distinct Tlag before the commencement of emptying was observed in most subjects for both bread types. While no differences in GER were evident (p = 0.562), consumption of the oat bread significantly increased T1/2 by 18min and Tlag by 14min compared with the whole-wheat bread (p = 0.005 and p = 0.010, respectively). In addition, the oat bread significantly reduced iAUC2h for glucose and insulin responses compared with the whole-wheat bread (p = 0.001 and p < 0.001, respectively). There were no significant differences in GLP-1 response between the two breads (p = 0.892). The increased T1/2 and Tlag could offer a potential mechanism for the observed attenuation of postprandial glycaemia and insulinemia after consumption of the β-glucan-enriched oat bread compared with the whole-wheat bread. The study is registered at clinicaltrails.gov (NCT04571866).

The A1/A2 β-casein genotype of cows, but not their horn status, influences peptide generation during simulated digestion of milk

The effect of the horn status of cows on their milk composition and quality is a controversial research topic. In this study, 128 milk samples from 64 horned and 64 disbudded Brown Swiss and Original Braunvieh cows were collected from alpine farms where both horned and disbudded cows were grazing on mountain pastures. The samples were analyzed for their detailed composition and protein digestion in a simulated in vitro digestion (INFOGEST). To exclude probable influences on digestion, the β-CN genotype with its variants A1 and A2 was also included in the study. The effects of horn status and β-CN genotype were investigated in linear mixed models, which included additional influencing random factors such as Original Braunvieh blood proportion, stage of lactation, and farm. Horn status did not have any effect on milk composition or digestion. In contrast, milk from A1A1 cows showed a different protein digestion than milk of A1A2 and A2A2 cows in the gastric phase, including smaller amounts of β-casomorphin(BCM)21-associated peptides and larger amounts of BCM11-associated peptides. Abundances of BCM7 did not differ between β-CN genotypes. At the end of the intestinal phase, the digested milk of A1A1 and A2A2 β-CN genotypes did not differ.

Simulated in vitro infant digestion and lipidomic analysis to explore how the milk fat globule membrane modulates fat digestion

We hypothesized that the addition of milk fat globule membranes (MFGMs) to infant formula would improve its lipolysis, making it more similar to human milk (HM) and superior to commercial infant formula (CIF) in fat digestion. Therefore, we prepared two model infant formulas (MIFs) by adding MFGMs to dairy ingredients in different ways and compared their fat digestion behavior with those of HM and CIF. MFGMs were added alone (MIF1) and with other milk-based materials (MIF2) before homogenization. The addition of MFGMs reduced the flocculation of lipids and proteins in the gastric phase and promoted lipolysis in the intestine phase. The amount of free fatty acids released followed the order of HM > MIF1 > CIF ≥ MIF2. After digestion, the number of different glyceride species between each sample and HM reached 64 (MIF1), 73 (MIF2), 67 (CIF1), and 72 (CIF2). In conclusion, the fat digestion of MIF1 had the highest similarity with HM.

Effect of gastrointestinal digestion on the stability, antioxidant activity, and Caco-2 cellular transport of pigmented grain polyphenols.

Grain polyphenols are known to possess several health properties. However, their digestive stability and intestinal absorption have not been fully elucidated. This study investigated the fate of pigmented grain polyphenols in the digestive system. Purple rice, purple barley, purple wheat, and blue wheat extracts were subjected to simulated gastric and intestinal phase digestion, followed by Caco-2 cellular transport. Phenolic profiling and antioxidant activity were determined using benchtop assays and an ultra-high-performance liquid chromatography-2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid free radical) (UHPLC-ABTS•+) system. The results demonstrated a decrease in the total phenolic content of extracts after digestion, with purple rice extract retaining the highest phenolic content (79%) and ABTS•+antioxidant activity (31%). Antioxidant activity was retained the most during the gastric phase; however, dominant antioxidant compounds were not detected after intestinal digestion. Significant variations in phenolic composition and radical scavenging activity were detected after digestion. Protocatechuic acid, vanillic acid, apigenin, and chrysoeriol were all transported across the intestinal barrier. The findings of this study provide novel insights into the in vitro stability and antioxidant activity of cereal grain polyphenols after simulated digestion.

Vitamin D3 Bioaccessibility from Supplements and Foods-Gastric pH Effect Using a Static In Vitro Gastrointestinal Model.

Vitamin D3 deficiency is a global phenomenon, which can be managed with supplementation and food fortification. However, vitamin D3 bioaccessibility may depend on factors such as matrix composition and interactions throughout the gastrointestinal (GI) tract. This research focused on the effect of different matrices on vitamin D3 content during digestion, as well as the effect of pH on its bioaccessibility. The INFOGEST protocol was employed to simulate digestion. Three different types of commercial supplements, two foods naturally rich in vitamin D3, and three fortified foods were investigated. High-Performance Liquid Chromatography was used to determine the initial vitamin D3 content in the supplements and foods, as well as after each digestion stage. The results indicate that the foods exhibited higher bioaccessibility indices compared to the supplements and a higher percentage retention at the end of the gastric phase. The pH study revealed a positive correlation between an increased gastric pH and the corresponding content of vitamin D3. Interestingly, exposing the matrix to a low pH during the gastric phase resulted in an increased intestinal content of D3. Vitamin D3 is more bioaccessible from foods than supplements, and its bioaccessibility is susceptible to changes in gastric pH. Fasting conditions (i.e., gastric pH = 1) enhance the vitamin's bioaccessibility.

Enhancing probiotic viability: Impact of soy hull polysaccharide concentration on stabilized high-internal-phase emulsions encapsulated with Lactobacillus plantarum and their release during gastrointestinal digestive

This study investigated the impact of soy hull polysaccharide (SHP) concentration on the formation of high-internal-phase emulsions (HIPEs) stabilized with soy protein isolate (SPI), encapsulated with Lactobacillus plantarum, and explored its gastrointestinal digestive mechanism. The results of Zeta potential, particle size and rheological properties revealed the excellent viscoelastic and thermal stability of the HIPEs. Compared to free probiotics, the in vitro digestion of probiotics encapsulated with 1.8% SHP HIPEs demonstrated a significant improvement in activity, with an encapsulation efficiency of 71.1%. Throughout the three stages of Gastrointestinal Tract (GIT) digestion, HIPEs maintained robust stability during the gastric digestion phase. Subsequent to trypsin enzymolysis, interactions between –NH3+ and –COOH led to binding and aggregation, initiating the collapse of HIPEs' structure. Concurrently, the hydrolyzed SHP and SPI formed small molecules of that further combine and flocculate. This critical juncture resulted in the release of L. plantarum into the simulated colonic environment. These findings proposed a promising strategy for employing HIPEs-encapsulated probiotics as targeted delivery systems in food applications.

Encapsulation and Characterization of Proanthocyanidin Microcapsules by Sodium Alginate and Carboxymethyl Cellulose.

Proanthocyanidins are important compounds known for their antioxidant and radical scavenging properties, but they are highly sensitive to light, heat, oxygen, and pH. In our study, proanthocyanidin was encapsulated using sodium alginate and carboxymethyl cellulose to enhance controlled release, pH stability, metal ion tolerance, temperature resistance, time release, the microencapsulation of food additives stability, antioxidant capacity analysis, and the storage period tolerance of proanthocyanidin. Fourier transforms infrared (FTIR) analysis and full-wavelength UV scanning indicated the successful immobilization of proanthocyanidins into the polymeric microcapsules. The flowability and mechanical properties of the microcapsules were enhanced. Moreover, proanthocyanidin microcapsules exhibited higher thermal, pH, metal ion, time, and microencapsulation food additive stability. In addition, due to their high antioxidant properties, the proanthocyanidin microcapsules retained a greater amount of proanthocyanidin content during the gastric phase, and the proanthocyanidin was subsequently released in the intestinal phase for absorption. Thus, the study provided a systematic understanding of the antioxidant capabilities and stability of proanthocyanidin microcapsules, which is beneficial for developing preservation methods for food additives.

Impact of β-casein phenotype on the physical properties of skim milk powders and their subsequent digestion characteristics

This study investigated the physical properties of skim milk powders containing β-casein A1/A1, A1/A2 or A2/A2 phenotypes and determined their digestion properties. Rehydrated skim milk powders all had a type A heat coagulation profile (HCT); although A2/A2 milk had a different local maximum and minimum HCT, compared to A1/A1 and A1/A2 milks. Differences in the rehydration properties of milk powders appeared to be related to the presence of β-casein A1 in reconstituted A1/A1 and A1/A2 milks since they were characterised by smaller casein micelles and greater levels of κ-casein, compared to A2/A2 milk. All reconstituted samples displayed protein aggregation and coagulum formation within the first 5 min of gastric digestion, at which time the pH ranged from 6.0 to 5.5. During digestion of reconstituted A2/A2 milk, casein breakdown was slower, compared to that of A1/A1 or A1/A2 milks. The final gastric clot obtained from the A2/A2 sample possessed a tight protein network, containing a greater level of calcium and aggregated β-sheets. In this regard, the dry weight of the separated clot after the final gastric phase was significantly higher by 29 and 68 % in A2/A2 digesta compared to that in A1/A1 or A1/A2 digests, respectively. Overall, this study shows that for rehydrated skim milk powders there was a significant difference in the level of gastric protein-breakdown between milks containing β-casein A1 and milk containing only β-casein A2. This may have significant implications during in vivo gastric digestion and emptying.

Fish oil encapsulation by genipin-crosslinked complex coacervation between gelatin and different anionic polysaccharides

Herein, a combination approach of bovine bone gelatin (BBG)/anionic polysaccharide (AP) complex coacervation with genipin crosslinking was developed to successfully fabricate fish oil-loaded genipin-crosslinked BBG/AP (fish oil@BBG-genipin-AP) powders. The genipin crosslinking process promoted the formation of larger fish oil@BBG-genipin-AP particles from the BBG/AP particles and fish oil@BBG/AP particles. AP types (gum Arabic, GA; sodium alginate, SA; sodium carboxymethyl cellulose, CMC) and concentrations significantly affected the critical pH to form complex coacervated particles, the powder physicochemical properties, the powder oxidative stability, and the powder in vitro digestion. The fish oil@BBG-genipin-CMC powder at the CMC preparation concentration of 17.5 mg/mL showed the highest loading capacity value (44.3% ± 0.8%), almost the highest encapsulation efficiency value (90.9% ± 0.7%), and the highest encapsulation yield (91.3% ± 2.0%). Due to the environmental pH change, the powders changed to emulsion droplets in the gastric phase and then released free fatty acids in the small intestinal phase. The highest FFA release percentages after the gastrointestinal phase (2 h in the gastric phase and 2 h in the small intestinal phase) were dependent on both AP types and their concentrations (GA: 64.8 ± 2.9%, 62.5 mg/mL; SA: 55.0 ± 3.1%, 15 mg/mL; and CMC: 48.9 ± 1.5%, 12.5 mg/mL). GA at a concentration of 62.5 mg/mL might be the best system to prepare fish oil@gelatin-genipin-anionic polysaccharide powders for fish oil digestion. This work provided useful information to develop oil-encapsulation powders for functional foods and understand the influences of wall materials on the fabrication and properties of powder foods.

The Behavior of Phenolic Compounds from Apples during Simulated Gastrointestinal Digestion with Focus on Chlorogenic Acid.

The fate of phenolic compounds during digestion is important for their bioactive effects in the digestive tract. The aim was to study the various phenolic compounds occurring in the peel and flesh of apples in in vitro simulated gastrointestinal digestion, focusing on the behavior of chlorogenic acids. Additionally, the behavior of individual chlorogenic acids (chlorogenic, neochlorogenic, and cryptochlorogenic) was studied in models of simulated salivary, gastric, and intestinal fluid electrolyte solutions (SSF, SGF, SIF). At the end of the intestinal phase of the digestion of peel and flesh, the amount of recovered dihydrochalcones and flavonols increased or was similar to the amount in the gastric phase, which showed their stability. Anthocyanins and flavan-3-ols decreased, which suggests their biotransformation. Chlorogenic acid isomerized into neochlorogenic and cryptochlorogenic acid: chlorogenic acid from the peel into 22% and 41% of the isomers in the salivary and intestinal phases, respectively; chlorogenic acid from the flesh into 12% of the isomers in the intestinal phase. Similarly, chlorogenic acid isomerized in model solutions (20% and 26% of the isomers in SSF and SIF, respectively). Neochlorogenic and cryptochlorogenic acid isomerized in SSF and SIF into other two forms. They were all stable in SGF. For bioactive effects in the digestive tract, the biotransformation of chlorogenic acids should be considered.