Simulated Gastric Fluid Digestion Research Articles

Enhancement of Astaxanthin Bioaccessibility by Encapsulation in Liposomes: An In Vitro Study.

Astaxanthin was encapsulated in liposomes by a thin layer dispersion and ultrasound method using soybean phospholipid. The digestion properties of liposomes for encapsulating astaxanthin were investigated in light of particle size, size distribution, zeta potential, and microstructure during in vitro digestion as a function of time. These results exhibited that the average particle size increased gradually with liposomal vesicles retained round shapes and a fairly uniform distribution after passage through the simulated gastric fluid digestion. The result revealed that astaxanthin-loaded liposomes were stable in low pH conditions. It was also found that the mixed micelles formed in a simulated intestinal fluid. The zeta potential of astaxanthin-loaded liposomes had a decrease in negativity after digestion. In comparison with free astaxanthin, there was an appreciable increase in the bioaccessibility of astaxanthin after encapsulation in liposomes. This enhancement can be attributed to more soluble astaxanthin in the mixed micelles for astaxanthin-loaded liposomes. It indicated that the barrier of the liposomal bilayer could inhibit astaxanthin fading and leaking after encapsulation in liposomes. These results provide useful information for designing more stable delivery systems in the gastrointestinal tract and improving the bioaccessibility of lipophilic nutraceuticals.

Fabrication of starch-based emulsion gel beads by an inverse gelation technique for loading proanthocyanidin and curcumin

In this study, large-scale emulsion gel beads were fabricated using an inverse emulsion gelation technique. Gelation was achieved by simple starch retrogradation, which enabled dual loading of proanthocyanidin and curcumin. The properties and morphologies of the fabricated emulsion gel beads were characterized by means of laser particle size analysis, rheological measurement, texture profile analysis, optical microscopy, and scanning electron microscopy. The average size of the emulsion gel beads ranged from 2.8 to 5.9 mm. With the increase in the starch concentration from 9.1% to 33.3%, the hardness of the gel beads was increased 8.8-fold, from 195.31 ± 30.73 g to 1734.94 ± 155.17 g, whereas the swelling ratio of the beads showed a decreasing trend under different treatment conditions (pH range from 1.5 to 12 and temperature range from 25 to 80 °C). Increasing the starch concentration from 9.1% to 33.3% also resulted in a decrease in the release ratio of proanthocyanidins and curcumin from 68.32% to 16.66% and from 7.00% to 0.45%, respectively, after simulated gastric fluid digestion for 2 h, indicating that starch-based emulsion gel beads can tolerate the damage imposed by the gastric environment. Disruption of the starch gel network by amylase hydrolysis and digestion in simulated intestinal fluid for 4 h caused a cumulative release of proanthocyanidins and curcumin from the beads in excess of 75% and 28%, respectively. Therefore, starch-based emulsion gel beads, which combine the advantages of emulsion and hydrogel systems, are ideal carriers for loading hydrophilic and hydrophobic active ingredients.

The Effect of Infant Gastric Digestion on Human Maternal Milk Cells.

Human breast milk contains a variety of cell types that have potential roles in infant immunity and development. One challenge associates with defining the purpose(s) of milk cells in the infant is a poor understanding of the effect of digestion on cell fate. This study first demonstrates that milk cell death occurs after gastric digestion in mice. Then flow cytometry and RT-PCR are used to understand the mechanism of human milk cell death and quantify live cell types before and after simulated gastric digestion. This study finds that digestion in simulated gastric fluid for 30 min reduces cell viability from 72% to 27%, with most cell death is caused by the acidic pH. The primary mechanism of cell death is caspase-mediated apoptosis. The non-cellular components of milk offer only mild protection against cell death from stomach acid. Gastric digestion does not select for a specific resilient cell population to survive-most cell types die in equal proportions in the gastric environment. Taken together, these results provide a foundation with which to understand the fate of human breast milk cells in the infant's intestine and beyond.

Adenanthera pavonina, a potential plant-based protein resource: Seed protein composition and immunohistochemical localization of trypsin inhibitors.

Adenanthera pavonina, an underutilized tropical tree, is being promoted as an alternative food source for meeting the nutritional needs of human and animals. In this study, we have shown that trypsin inhibitors as one of the predominant proteins in the seeds of A. pavonina. DE-52 column chromatography resulted in the identification of four peaks with trypsin inhibitor activity. SDS-PAGE and immunoblot analyses revealed DE-52 peaks A and B were enriched in 17 and 15kDa proteins and these proteins cross-reacted against soybean trypsin inhibitor antibodies. Simulated gastric fluid digestion revealed that the 15-17kDa proteins are resistant to pepsin digestion. Roasting the seeds lowered the trypsin inhibitor activity while boiling intact seeds elevated the enzyme activity. However, the trypsin inhibitor activity was completely abolished when the seeds were boiled without their seed coats. Immunohistochemical detection and confocal microscopy demonstrated that trypsin inhibitors were localized in the cell cytosol.

Gastrointestinal digestive fate of whey protein isolate coated liposomes loading astaxanthin: Lipolysis, release, and bioaccessibility

Whey protein isolate coated astaxanthin-loaded liposomes were prepared in this work. The gastrointestinal digestive fate of whey protein isolate coated astaxanthin-loaded liposomes was evaluated in terms of particle size, size distribution, zeta potential, and morphology during in vitro digestion as a function of time. Analysis on the particle size and morphology of whey protein isolate coated astaxanthin-loaded liposomes showed that the majority of particles maintained spherical shape with a progressive increase of particle size after passage through the digestion. The zeta potential on whey protein isolate coated astaxanthin-loaded liposomes became highly negative after digestion. As compared in uncoated liposomes, the astaxanthin release in whey protein isolate coated liposomes was slower in simulated gastric fluid digestion, while was faster in simulated intestinal fluid digestion. Through in vitro digestion, the bioaccessibility of astaxanthin was improved significantly after whey protein isolate coating. It was also found that the whey protein isolate coating could protect liposomes against destruction and suppress the lateral mobility of pyrene, resulting in lower micropolarity and fluidity of liposomal membrane during the digestion. These findings may guide the potential application of whey protein isolate coated liposomes for improving the bioaccessibility and stability of astaxanthin in nutraceuticals and pharmaceutics. • The digestion behavior of whey protein isolate coated astaxanthin-loaded liposomes. • Astaxanthin-loaded liposomes after coating were stable under gastric conditions. • The bioaccessibility of astaxanthin was improved. • Whey protein isolate coating could protect liposomes during the digestion.

Rapid Identification of Common Poisonous Plants in China Using DNA Barcodes

Toxic plants have been a major threat to public health in China. However, identification and tracing of poisoned species with traditional methods are unreliable due to the destruction of plant morphology by cooking and chewing. DNA barcoding is independent of environmental factors and morphological limitations, making it a powerful tool to accurately identify species. In our study, a total of 83 materials from 26 genera and 31 species of 13 families were collected and 13 plant materials were subjected to simulated gastric fluid digestion. Four markers (rbcL, trnH-psbA, matK, and ITS) were amplified and sequenced for all untreated and mock-digested samples. The effectiveness of DNA barcoding for the identification of toxic plants was assessed using Basic Local Alignment Search Tool (BLAST) method, PWG-Distance method, and Tree-Building (NJ) method. Except for the matK region, the amplification success rate of the remaining three regions was high, but the sequencing of trnH-psbA and ITS was less satisfactory. Meanwhile, matK was prone to be more difficult to amplify and sequence because of simulated gastric fluid. Among the three methods applied, BLAST method showed lower recognition rates, while PWG-Distance and Tree-Building methods showed little difference in recognition rates. Overall, ITS had the highest recognition rate among individual loci. Among the combined loci, rbcL + ITS had the highest species recognition rate. However, the ITS region may not be suitable for DNA analysis of gastric contents and the combination of loci does not significantly improve species resolution. In addition, identification of species to the genus level is sufficient to aid in the clinical management of most poisoning events. Considering primer versatility, DNA sequence quality, species identification ability, experimental cost and speed of analysis, we recommend rbcL as the best single marker for clinical identification and also suggest the BLAST method for analysis. Our current results suggest that DNA barcoding can rapidly identify and trace toxic species and has great potential for clinical applications. In addition, we suggest the creation of a proprietary database containing morphological, toxicological and molecular information to better apply DNA barcoding technology in clinical diagnostics.

Effects of in vitro simulated digestion on the free and bound phenolic content and antioxidant activity of seven species of seaweeds

SummaryThe effects of simulated gastrointestinal digestion on the content and antioxidant activity of phenolics of seven seaweeds were investigated: Two methods of digestion were used – simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) to mimic the stomach and upper intestinal environment. Results showed that SIF can significantly increase the free phenolic content of all tested seaweeds. The total phenolic content of the seaweeds increased in range from 4.16 to 17.24 mg GAE/g before simulated digestion to 4.08 to 40.37 mg GAE/g after digestion. The antioxidant activity of seaweed‐bound phenolics was superior to that of free phenolics. Among the seven varieties of seaweeds, Sargassum thunbergii and Sargassum kjellmanianum contained the highest content of bound phenolics after SGF digestion. Bound phenolics of Undaria pinnatifida and Sargassum thunbergii showed the highest in vitro ABTS+ free radical scavenging ability, while Sargassum thunbergii and Sargassum fusiforme showed the highest in vitro FRAP antioxidant activity.

Effects of Maillard reaction on structural modification and potential allergenicity of peanut 7S globulin (Ara h 1).

Ara h 1 is a major food allergen in peanuts. Recently, many studies have revealed that the Maillard reaction (MR) affects the allergenicity of food proteins. To investigate the influence of the MR on the allergenicity of Ara h 1, R-Ara h 1 was processed with glucose in dry heating conditions for different periods. The extent of the MR was assessed by four methods. The changes in secondary and tertiary structures were characterized through spectroscopy assays. Advanced glycation end products (AGE) structures were identified by protein sample dry heating for 60 min, indicating the formation of AGE-Ara h 1. Simulated gastric fluid (SGF) digestion analysis showed that AGE-Ara h 1 has higher resistance to peptic digestion than R-Ara h 1. The BALB/c mouse model was also utilized to explore the effect of the MR on the allergenicity of Ara h 1, and the results showed that the Th2-type cytokines, antibodies, and histamine content increased, and there was a greater degree of degranulation of rat basophilic leukemia (RBL) cells in the AGE-Ara h 1 group compared with the R-Ara h 1 group. During the process of dry heating, proteins participated in the MR with changes in secondary and tertiary structures. The condition applying a temperature of 100 °C for 60 min caused the formation of AGE-Ara h 1. Simulated gastric fluid digestion analysis showed that AGE-Ara h 1 had a greater resistance to peptic digestion than R-Ara h 1. The BALB/c mouse model showed that AGE-Ara h 1 had more allergenicity, indicating that the MR could enhance the allergenicity of Ara h 1. © 2020 Society of Chemical Industry.

Curcumin, casein and soy polysaccharide ternary complex nanoparticles for enhanced dispersibility, stability and oral bioavailability of curcumin

Curcumin, casein and soy soluble polysaccharide ternary complex nanoparticles were produced in the water phase using alkaline dissolution, acidification and high-pressure homogenization. FTIR spectra showed that hydrogen bonding, hydrophobic and electrostatic interactions led to the formation of the nanoparticles. The nanoparticles had strong curcumin solubilizing power. The curcumin concentrations in the nanoparticle dispersions were 2.5–20 mg/mL, the curcumin loading efficiencies were ~97%, and the highest curcumin loading content was 48.6%. The nanoparticles had z-average hydrodynamic diameters of ~3.6 × 102 nm, and good physical stability and curcumin chemical stability after 30 days of storage at 25 °C. Due to the polysaccharide surfaces, the nanoparticles were dispersible in acidic and neutral solutions as well as re-dispersible in water after lyophilization. About 52.3% of the curcumin was released after 2 h digestion in simulated gastric fluid followed by 2 h digestion in simulated intestinal fluid. After oral administration in mice, the nanoparticle treatment group increased the curcumin oral bioavailability by 3.4-fold compared with the curcumin/Tween 20 group. This study showed that the ternary complex nanoparticles were an effective system for curcumin loading, protection and oral delivery.

Encapsulation of quercetin-loaded β-lactoglobulin for drug delivery using modified anti-solvent method

Many scientists use proteins as attractive bio-availability enhancers for natural compounds and pharmaceuticals which have poor water solubility, due to their natural abundance, amphiphilic nature, and desirable biocompatibility. Here, we investigate the preparation, characterization, and application of β-Lactoglobulin (BLG) based nanoparticles for encapsulation of quercetin, systematically. We used anti-solvent method that is common for nano particle preparation of water-soluble proteins. The procedure involves partial unfolding of protein molecules, limited aggregation in the presence of anti-solvent, crosslinking via chemical linker, and refolding of the constituent monomers. The results showed that acetone anti-solvent has significant effect on accumulation of BLG-quercetin nanoparticles. Adjustment of acetone content to the value of 10% v/v (acetone/water) followed by mild evaporation led to a notable improvement in Encapsulation Efficiency (EE%) and Loading Efficiency (LE%), which raised LE to 13.9%. In addition, reducing glutaraldehyde amount to 50% of equivalent, led to toxicity reduction of the drug carrier system. The nanoparticles with a mean particle size of about 180–300 nm and semispherical appearance were approved using Atomic Force Microscopic (AFM) and Field Emission Scanning Electron Microscopy (FESEM) methods. Protein nanoparticles may be digested at different stages of the gastrointestinal tract, depending on acidity, ionic strength, or specificity of proteases (pepsin and trypsin). This study suggested that BLG as a resistant protein to peptic digestion forms nanoparticles that are digestible (compared to untreated BLG) by pepsin. As a result, satisfactory controlled release was achieved under simulated fast condition, i.e., digestion in simulated gastric fluid (SGF) at pH = 2 and then in simulated intestinal fluid (SIF). Finally, the mechanism of drug release into the buffer environment was well-fitted by the Korsmeyear-Peppas kinetic model. The conclusions of this study may apply not only to quercetin-BLG system, but also to a wide variety of encapsulation systems involving water-soluble protein and hydrophobic target compound, with adequate LE and reduced toxicity.

Effects of thermal processing methods and simulated digestion on the phenolic content and antioxidant activity of lotus leaves

The release and antioxidant activity of the phenolics in lotus leaves were changed by various processing methods and in vitro simulated gastric fluid (SGF) and intestinal fluid (SIF) digestion. The total phenolic content (TPC), total flavonoid content (TFC), and antioxidant capacity of FRAP and ABTS were the highest in the sample processed by microwave vacuum drying. The SGF treatment significantly reduced the TFC in lotus leaves treated by various thermal processing methods but had no significant effect on the TPC. However, SIF digestion reduced the TPC in lotus leaves treated with different thermal processing methods but increased the TFC. The SGF digestion reduced the ABTS of lotus leaves, whereas SIF digestion had no significant effect on the ABTS antioxidant capacity. However, both SGF and SIF digestion increased the FRAP antioxidant capacity. Previous steam heated followed by microwave vacuum drying is the optimal method for drying lotus leaves, after considering all factors. PRACTICAL APPLICATIONS: Phenolics and flavonoid from lotus leaf have antioxidant capacity that brings health benefits. However, the antioxidant capacity is affected by various processing methods and digestion. Therefore, the development of processing methods is very important. Our results show that previous steam heated followed by microwave vacuum drying is the optimal method for drying lotus leaves, considering the antioxidant capacity and flavor.

Composition of phenolic and antioxidant activity of water chestnut peel during digestion in vitro as affected by blanching time

ABSTRACT Water chestnut peels have good antioxidant activity. The effects of simulated gastric fluid (SGF) and intestinal fluid (SIF) fluid digestion in vitro on the active substance and antioxidant activity of water chestnut peels that were pre-treated using different boiling times (P10 and P30) were investigated. The results showed that the SGF obviously increased both the total phenolic content and total flavonoid content of water chestnut peels. The SGF digestion significantly enhanced both the FRAP and ABTS antioxidant capacity of water chestnut peels only blanched with P10. However, the SIF digestion significantly increased the FRAP and ABTS antioxidant capacity of all water chestnut peels regardless of whether these were pre-treated or not. The HPLC results showed that the simulated digestion in vitro enhanced the flavonoids content of the peels. Water chestnut peels could be used as an inexpensive source of natural functional food ingredients.

Boiling and roasting treatment affecting the peanut allergenicity.

Peanut allergy appears to be less prevalent in other parts of the world than North America and several European countries, and it has been proposed difference in cooking practices may be responsible. In this study, the boiling and roasting processes were investigated to find a potential method to enhanced or reduce the allergenicity. The allergenicity of different peanut products, as reflected by changes in ethology (diarrhea and weight loss) and pathology (splenomegaly and jejunum breakage) were observed, and relevant serological indexes were determined after feeding different peanut products. Different peanut proteins were used to analyze the ability to resistance digestion in simulated gastric fluid (SGF). Ultraviolet spectrum and CD spectra were used to analyze structure changes of Ara h 2 in roasting and boiling treatment. In the detection of the corresponding serological indicators, boiled peanuts show a lower sensitization than roasted and raw peanuts. SGF experiments demonstrated an increased resistance of roasted peanut protein to digestion. The results of ultraviolet spectrum and CD spectra showed that the roasting and boiling causes altered structures of the Ara h 2 peanut allergens. The summary show that different thermal processing may affect the structure and immunoreactivity, and the sensitization of roasted or boiled peanuts will be enhanced or reduced.

Effects of in vitro digestion on the composition of flavonoids and antioxidant activities of the lotus leaf at different growth stages

SummaryThe lotus leaf is rich in phenolic compounds and has good antioxidant activity. The effects of simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) digestions on the active substances and antioxidant activity of the lotus leaf in different growth stages (D25, D45 and D65) were investigated. The total phenolic content of D25 and D45 significantly increased by SGF digestion but not D65 compared to the DW treatment. However, SIF treatment saw markedly increased total phenolic content across all growth stages (D25, D45 and D65). Moreover, the total flavonoid content at all growth stages was increased by SIF digestion compared to SGF treatment. The pepsin and trypsin had different effects on the FRAP and ABTS (2, 2'‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid)) antioxidant activities of the lotus leaf. The SGF digestion increased the FRAP antioxidant capacity of the lotus leaf, and SIF digestion increased the ABTS antioxidant capacity of the lotus leaf. The HPLC results showed that the main flavonoid compound in the lotus leaf was isoquercetin. This study provides a theoretical basis for the development and utilisation of the lotus leaf as an inexpensive natural and functional food ingredient.

Characteristic of microencapsulated 1,3-dioleoyl-2-palmitoylglycerol and its application in infant formula powder

ABSTRACT1,3-Dioleoyl-2-palmitoylglycerol (OPO) is used widely as a food additive. However, the structured lipid is sensitive to oxygen and light in the production process. This results in the loss of its original nutrition and production of harmful substances. In this study, the OPO was microencapsulated using whey protein isolate and maltodextrin as the wall material and monostearin as an emulsifier by spray-drying technology added to the infant formula milk, in order to improve its oxidative stability. The OPO microcapsules were released in vitro through the simulated gastrointestinal tract; sensory evaluation of microencapsulated OPO in infant formula powder and nutrition absorption of microencapsulated OPO in infant formula power by animal experiments were investigated. The results showed that OPO microcapsules have a slow-release effect; after 2 h of simulated gastric fluid digestion, only 16.1 ± 3.2% of the oil was released from microencapsulated OPO, and after another 2 h of simulated intestinal fluid digestion, there was 92.3 ± 2.8% of oil released from the microencapsulated OPO. The infant formula with microencapsulated OPO has a uniform colour and no odour. The quality of infant formula with microencapsulated OPO was obviously better than infant formula with OPO by storage test. Everted mice gut sac experiments confirmed that microencapsulation did not affect absorption of mice to OPO in infant formula and prevented the loss of calcium. The study confirmed that addition of microencapsulated OPO makes infant formula more efficient for product quality and nutrition absorption.

High-throughput Screening of Potential Allergens from Complex Proteins of Large Yellow Croaker (Larimichthys crocea) by Mass Spectrometry

Abstract The allergenicity of large yellow croaker (Larimichthys crocea) proteins has been widely reported to cause many serious food safety problems. In this study, the protein sample extracted from Larimichthys crocea was digested and analyzed by reversed phase liquid chromatography coupled with tandem mass spectrometry (RPLC-MS/MS) for globally proteomic analysis, and the Larimichthys crocea proteins were digested with simulated gastric fluid (SGF) at different time intervals and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The digestion-resistant proteins were further done with in-gel digestion and analyzed by RPLC-MS/MS. Then, sequence homology analysis between identified proteins and known allergens was performed. Results showed that 33 kinds of distinct proteins were feasibly identified from Larimichthys crocea by RPLC-MS/MS and the protein band (approximately 44.0 kDa) presented in SDS-PAGE was considered as protein-resistant to SGF digestion. Two potential allergens, β-enolase and tropomyosin α−1 chain, were found from proteins resistant to SGF digestion by sequence homology analysis. It was observed that most of these SGF digestion-resistant proteins were potential allergens with high sequences similarity to the known protein allergens from other species. Therefore, this strategy provides an efficient alternative for potential allergens screening with high-throughput, which exhibits great potential application in fish protein allergens related food safety control.

Identification of triosephosphate isomerase as a novel allergen in Octopus fangsiao.

Octopus is an important mollusk in human dietary for its nutritional value, however it also causes allergic reactions in humans. Major allergens from octopus have been identified, while the knowledge of novel allergens remains poor. In the present study, a novel allergen with molecular weight of 28kDa protein was purified from octopus (Octopus fangsiao) and identified as triosephosphate isomerase (TIM) by mass spectrometry. TIM aggregated beyond 45°C, and its IgE-binding activity was affected under extreme pH conditions due to the altered secondary structure. In simulated gastric fluid digestion, TIM can be degraded into small fragments, while retaining over 80% of the IgE-binding activity. The full-length cDNA of O. fangsiao TIM (1140bp) was cloned, which encodes 247 amino acid residues, and the entire recombinant TIM was successfully expressed in Escherichia coli BL21, which showed similar immunoreactivity to the native TIM. Different intensity of cross-reactivity among TIM from related species revealed the complexity of its epitopes. Eight linear epitopes of TIM were predicted following bioinformatic analysis. Furthermore, a conformational epitope (A71G74S69D75T73F72V67) was confirmed by the phage display technology. The results revealed the physicochemical and immunological characteristics of TIM, which is significant in the development of hyposensitivity food and allergy diagnosis.

Rapid simulated gastric fluid digestion of in-seed/grain proteins expressed in genetically engineered crops

The speed of simulated gastric digestion of proteins expressed in genetically engineered (GE) crops is commonly used to inform the allergenicity risk assessment. However, persistence of purified proteins in simulated gastric fluid (SGF) is poorly correlated with the allergenic status of proteins. It has been proposed that the plant or food matrix may affect the digestion of proteins and should be considered in interpreting digestion results. Here the SGF digestion of several GE proteins both as purified preparations and in soybean, corn, and cotton seed/grain extracts (in-matrix) are compared. Cry1F, Cry1Ac, phosphinothricin acetyltransferase (PAT), aryloxyalkanoate dioxygenase-1 (AAD-1), aryloxyalkanoate dioxygenase-12 (AAD-12), and double mutant 5-enol pyruvylshikimate-3-phosphate synthase (2mEPSPS) were all found to rapidly digest both as purified protein preparations and in seed/grain extracts from GE crops expressing these proteins. Based on these results, purified protein from microbial sources is a suitable surrogate for proteins in-matrix when conducting SGF digestion studies.

In-Vitro Simulated Gastric Fluid Digestion and Immunogenicity of Different Crustacean Protein Extracts

To compare the immunogenicity and digestibility in-vitro simulated gastric fluid, the protein extracts of white-leg shrimp, Chinese shrimp (female and male shrimp were separated), Southern rough shrimp, Acetes chinensis, Mantis shrimp and crawfish were analyzed by SDS-PAGE, indirect ELISA and Western blotting. The results showed that except for Acetes chinensis, the larger proportion of molecular mass were near to 25 kDa (sarcoplasmic calcium-binding protein) and 38 kDa (tropomyosin). White-leg shrimp protein and Southern rough shrimp protein had a maximum similarity of 68.2%. White-leg shrimp protein had higher immunogenicity than others. There were much more IgE-binding bands in male Chinese shrimp protein, while Crawfish just had only one IgE-binding band (38 kDa, tropomyosin). In simulated gastric fluid system, the protein such as 25 kDa was rapidly degraded within 0.5 mins, while tropomyosin (38 kDa) was relatively resistant to pepsin digestion. The Western blotting results indicated that the allergenicity of those crustacean protein extracts still remained even they were digested with simulated gastric fluid for 60 min.

Multiplex comparison of the digestibility of allergenic and non-allergenic proteins in rice grains by in vitro digestion

To evaluate the digestibility of rice allergenic and nonallergenic proteins under the influence of the rice grain matrix, rice powder was subjected to in vitro digestion by simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). Rice proteins were extracted from the liquid and the solid phases and analysed by SDS–PAGE, and rice allergenic proteins were detected by a multiplex immunodetection method. The digestion of soluble proteins was carried out in both liquid and solid phases, while that of insoluble proteins only occurred in the solid phase. In SGF digestion, rice proteins were more quickly digested at pH 1.2 than at pH 2.0 or 2.5. Moreover, the digestibility of five kinds of rice allergenic proteins was influenced by pH level, heat processing, starch matrix, solubility, and protein properties, on a case-by-case basis. On the other hand, all detected rice allergenic proteins and non-allergenic proteins were rapidly digested in SIF.