Gluten Hydrolysate Research Articles

Inulin hydrolysis by inulinase immobilized covalently on magnetic nanoparticles prepared with wheat gluten hydrolysates

Inulinase can produce a high amount of fructose syrup from inulin in a one-step enzymatic process. Inulinase from Aspergillus niger was immobilized covalently on Fe3O4 magnetic nanoparticles functionalized with wheat gluten hydrolysates (WGHs). Wheat gluten was enzymatically hydrolyzed by two endopeptidases Alcalase and Neutrase and related nanoparticles were prepared by desolvation method. Magnetite nanoparticles were coated with WGHs nanoparticles and then inulinase was immobilized onto it using glutaraldehyde as crosslinking agent. Parallel studies employing differential scanning calorimetry and field emmision scanning electron microscopy were carried out to observe functional and structural variations in free inulinase during immobilization. Optimum temperature of immobilized inulinase was increased, while, pH and Km values were decreased compared to free enzyme. Overall, a 12.3 folds rise was detected in enzyme half-life value after Immobilization at 75 °C and enzyme preserved 70% of its initial activity after 12 cycles of hydrolysis with 75% of enzyme loading.

Using LC-MS to examine the fermented food products vinegar and soy sauce for the presence of gluten

A strict, lifelong gluten-free (GF) diet is currently the only treatment for coeliac disease (CD). Vinegar and soy sauce are fermented condiments that often include wheat and/or barley. During fermentation cereal proteins are partially degraded by enzymes to yield peptide fragments and amino acids. Whether these fermented products contain intact or degraded gluten proteins and if they are safe for people with CD remains in question. LC-MS offers the benefit of being able to detect hydrolysed gluten that might be present in commercial vinegar and soy sauce products. LC-MS revealed the presence of gluten in malt vinegar, wherein the identified peptides derived from B-, D- and γ-hordein from barley, as well as γ-gliadin, and HMW- and LMW-glutenins from wheat that are known to contain immunopathogenic epitopes. No gluten was detected in the soy sauces examined despite wheat being a labelled ingredient indicating extensive hydrolysis of gluten during soy sauce production.

Corn gluten hydrolysate regulates the expressions of antioxidant defense and ROS metabolism relevant genes in H2O2-induced HepG2 cells

Reactive oxygen species (ROS) and antioxidants are known to influence the expressions of a number of genes. This study aimed to investigate the effects of corn gluten hydrolysate (CGH) on the expressions of antioxidant defense and ROS metabolism relevant genes in HepG2 cells. Eighty-four genes involving in antioxidant defense and ROS metabolism were analyzed. The results showed that the genes such as GPX3, GPX5, SOD3, CYGB, SEPP1 and MT3 that down-regulated in oxidative damaged HepG2 cells were, however, up-regulated in CGH1 (molecular weights <1 kDa)-pretreated cells, suggesting that CGH1 could improve the expressions of several antioxidant genes that were initially suppressed by oxidative stress. In addition, pathway analysis demonstrated that antioxidant ability of CGH1 was associated with arachidonic acid metabolism (P < .05). CGH1 reduced the expression of EPHX2, which may protect against H2O2-induced cell membrane damage by increasing cellular epoxyeicosatrienoic acid (EET) and forming EET-phospholipids for cell membrane.

Identification and characterization of proteolytically resistant gluten-derived peptides.

The lack of digestibility of certain gluten proteins is essential in the development of celiac disease (CD). Gluten proteins are remarkably resistant to luminal and brush-border proteolysis owing to their high proline and glutamine content. Consequently, large fragments remain intact after digestion exerting toxic effects. Intestinal brush-border membrane vesicles (BBMV) have been described as having strong proteolytic activity mainly through prolyl endopeptidase enzymes. The purpose of this work was to monitor the gastrointestinal digestion of specific CD epitopes by means of an in vitro gastrointestinal digestion model that included incubation with brush-border membrane enzymes. Gluten hydrolysates were characterized by mass spectrometry and the immunologic peptides were tracked by searching the main T-cell stimulating epitopes which have been widely described. The immunologic potential of gluten hydrolysates was further analysed by enzyme-linked immunosorbent assay (ELISA). The results showed that the composition of gluten hydrolysates depended on the digestion time and protein structural characteristics. On the other hand, the main T-cell stimulating epitopes formed during hydrolysis depend on the precursor protein. Glutenin oligopeptides were degraded faster whereas gliadin, mainly α-gliadin oligopeptides, remained intact for a long time. MS-based analysis showed that the formation of the epitopes from γ-gliadin and ω-gliadin or glutenin was favoured but they were generally degraded during the gastrointestinal treatment. However, the peptides containing the epitope PFPQPQLPY (α-gliadin) remained intact even after 180 min of digestion time. Overall, from all the epitopes tracked, PFPQPQLPY was the most resistant to in vitro BBMV digestion.

Purification and biochemical characterization of a novel intestinal protease from Scorpaena notata

ABSTRACTA new protease was isolated from the intestine of small red scorpionfish. After ammonium sulfate precipitation, the enzyme was purified to homogeneity by a two-step chromatography with 6.69% recovery and fivefold increase in specific activity. The molecular weight of the protease was about 24 kDa as estimated by size exclusion chromatography and sodium dodecyl sulfate–polyacrylamide gel electrophoresis. The enzyme optimum pH and temperature were pH 10.0 and 40°C, respectively. The protease was stable at temperatures below 40°C and over a broad pH range (8.0–11.0). The Km and Kcat values were 0.36 mmol L−1 and 1.61 s−1, respectively. Interestingly, the enzyme presented specificity for casein, egg albumin, bovine serum albumin, and gelatin with obtained degrees of hydrolysis ranging from 3.14% to 6.58%, after 2 h of hydrolysis. Moreover, gluten hydrolysate analysis confirmed protein hydrolysis and solubilization. These results suggested the potential use of the protease in the preparation of food protein hydrolysates with interesting properties.

New Method To Produce Kokumi Seasoning from Protein Hydrolysates Using Bacterial Enzymes.

In the present study, we demonstrate a novel use for a commercially available glutaminase that can be used as a γ-glutamyltranspeptidase in kokumi seasoning production. Soy protein and gluten were hydrolyzed using a protease isolated from Bacillus licheniformis. The resulting protein hydrolysates were γ-glutamylated with a γ-glutamyltranspeptidase, which is sold as a glutaminase from Bacillus amyloliquefaciens, to produce kokumi seasonings. For γ-glutamylation of soy protein hydrolysate, glutamine was added to the reaction mixture. On the other hand, reaction conditions for enzymatic proteolysis were optimized to liberate glutamine from gluten in large amounts, and the addition of glutamine was not required for γ-glutamylation of gluten hydrolysate. The soy protein and gluten hydrolysates as well as their γ-glutamylated products were subjected to taste evaluation. Soy protein hydrolysates were bitter. Although γ-glutamylation significantly reduced bitterness, the taste was still considered unfavorable. γ-Glutamylated gluten hydrolysate is the most preferable sample and had significantly enhanced thickness, kokumi, and umami tastes, with a moderate increase in saltiness.

Effects of wheat gluten hydrolysates fractionated by different methods on the growth and fermentation performances of brewer's yeast under high gravity fermentation

Summary Wheat gluten hydrolysates (WGH) were fractionated through ultrafiltration membrane with molecular weight (Mw) cut-off of 3 kDa and ethanol precipitation, respectively. WGH and their fractions were used to examine their effects on the growth and fermentation performances of brewer's yeast under high gravity fermentation. Results showed that WGH and their fractions exhibited significant differences in biomass accumulation, viability, ethanol yield, free amino nitrogen and sugar consumptions under high gravity fermentation. Compared to WGH, the fractions with Mw < 3 kDa and the supernatant of WGH treated with ethanol precipitation showed better fermentation performance for brewer's yeast. The relatively lower molecular weight and the higher levels of Leu, Lys, His and Arg in these two fractions might be responsible for their bioactivity for brewer's yeast. Thus, both ultrafiltration and ethanol precipitation could be used as efficient methods for enriching peptides with significant growth- and fermentation-promoting activity for brewer's yeast under high gravity fermentation.

Foaming and air-water interfacial characteristics of solutions containing both gluten hydrolysate and egg white protein

Enzymatically hydrolyzed wheat gluten can be a viable alternative for traditional animal-based foam stabilizing proteins in food systems. Gluten hydrolysates (GHs) can be considered for (partially) replacing surface-active food proteins such as those of egg white (EW). We here studied the foaming and air-water (A-W) interfacial characteristics of mixed GH + EW protein solutions. GH solutions had much higher (P < 0.05) foaming capacities than EW solutions, while the latter had much higher (P < 0.05) foam stability than the former. When only one sixth of EW proteins was replaced by GHs, the foaming capacity of the mixtures was as high as or higher than that of the GH solutions. Furthermore, when half of the EW protein was replaced by GH, the mixtures still had high foam stability. It thus seems that both GH and EW proteins contribute positively to the foaming characteristics of the mixtures. However, measurements of the early stages of diffusion to and adsorption at the interface, plus measurements of surface dilatational moduli at the interface, both suggested that the adsorbed protein film consists primarily of GHs rather than of EW proteins. Nonetheless, FS was higher when EW proteins were present. Mixed GH + EW solutions have a higher resistance to coalescence than GH solutions. Therefore, it is hypothesized that EW proteins form a secondary protein layer below the A-W interface which is maintained by interactions with adsorbed GH constituents, thereby providing bubbles with an additional resistance to coalescence.

Controlled enzymatic hydrolysis for improved exploitation of the antioxidant potential of wheat gluten

The aim of the study was to find the optimal operational and process parameters for the enzymatic hydrolysis of wheat gluten in a batch stirred bioreactor regarding both degree of hydrolysis and antioxidant capacity of the obtained hydrolysates. It appeared that impeller geometry and agitation speed influenced the mass transfer resulting in enhanced gluten hydrolysis. The highest initial reaction rate (0.83 ± 0.02 min−1) and degree of hydrolysis (30.47%) were achieved with the pitched four-bladed impeller and agitation speed of 350–450 rpm, conditions which provided proper balance between requirements for adequate mass/heat transfer and low shear stress. The impact of other process conditions including gluten concentration, temperature, pH and enzyme-gluten (E/S) ratio on the enzymatic reaction was investigated by applying a Box-Behnken experimental design from the viewpoint of the degree of hydrolysis (DH) and antioxidant activity. Three models obtained allowed calculation of the hydrolysis degree, and both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulpfonic acid) radical scavenging activity from a given set of reaction conditions with good predictability. The statistical analysis showed that each variable had a significant effect on degree of hydrolysis and the antioxidant capacity of both tested systems. Hydrolysis up to around DH 15% improved DPPH radical scavenging activity, while excessive hydrolysis worsened it. The ABTS activity of the hydrolysates was not associated with the DPPH activity nor with the DH, revealing that it was not possible to fulfill all desirable quality requirements (maximum degree of hydrolysis and protein yield, maximum DPPH and ABTS scavenging activities) by using the same reaction conditions. Overall, the study might contribute to approve wheat gluten, a by-product of wheat starch industry, as an accessible and cheap source of bioactive compounds for the development of novel nutraceuticals, cosmetics and drugs.

Production of a novel wheat gluten hydrolysate containing dipeptidyl peptidase-IV inhibitory tripeptides using ginger protease.

Wheat gluten is a Pro-rich protein complex comprising glutenins and gliadins. Previous studies have reported that oral intake of enzymatic hydrolysates of gluten has beneficial effects, such as suppression of muscle injury and improvement of hepatitis. Here, we utilized ginger protease that preferentially cleaves peptide bonds with Pro at the P2 position to produce a novel type of wheat gluten hydrolysate. Ginger protease efficiently hydrolyzed gluten, particularly under weak acidic conditions, to peptides with an average molecular weight of<600Da. In addition, the gluten hydrolysate contained substantial amounts of tripeptides, including Gln-Pro-Gln, Gln-Pro-Gly, Gln-Pro-Phe, Leu-Pro-Gln, and Ser-Pro-Gln (e.g. 40.7mg/g at pH 5.2). These gluten-derived tripeptides showed high inhibitory activity on dipeptidyl peptidase-IV with IC50 values of 79.8, 70.9, 71.7, 56.7, and 78.9μM, respectively, suggesting that the novel gluten hydrolysate prepared using ginger protease can be used as a functional food for patients with type 2 diabetes.

Production of wheat gluten hydrolyzates by enzymatic process at high pressure.

A novel process for producing wheat gluten enzyme hydrolyzates (WGEHs) was developed, using combinations of Flavourzyme 500MG, Alcalase 2.4L, Protamex, and Marugoto E at the high pressure of 300MPa, and the resultant hydrolyzates were analyzed for electrophoretic and hydrolytic properties. It was found that multiple-enzyme treatments increased the proportion of the electrophoretic bands less than 5kDa in the hydrolyzates greatly both at ambient pressure and 300MPa compared with one-enzyme hydrolysis. The contents of total soluble solids in the WGEHs increased considerably up to 89.75% according to the increase in the number of enzymes used at 300MPa compared with 79.37% found for the ambient-pressure hydrolysis. These characteristics together with the contents of soluble nitrogen and free amino acids clearly indicated that the high-pressure enzymatic process of this study is an efficient method for obtaining WGEHs with increased degree of hydrolysis.

Air-water interfacial properties of enzymatically hydrolyzed wheat gluten in the presence of sucrose

Enzymatically hydrolyzed wheat gluten proteins may be a valuable alternative to animal proteins as foaming agents in food. Studies of the air-water (A-W) interfacial properties of such hydrolysates in aqueous solutions contribute to the understanding of their functionality in food systems. We here studied the A-W interfacial characteristics of wheat gluten hydrolysates (GHs) in the absence and presence of sucrose. Sucrose increased (P < 0.05) the foaming capacity, which is the initial amount of foam formed, of GHs. This is probably related to an increased affinity of GHs for the A-W interface in the presence of sucrose, as could be observed by higher (P < 0.05) rates of diffusion to and adsorption at the A-W interface of the GH constituents in sucrose solution compared to those in water. Furthermore, the surface dilatational moduli of GH protein films at A-W interfaces were in most cases higher (P < 0.05) in a sucrose solution than in water. The latter could only partly be related to differences in foam stability. Surface hydrophobicity and intrinsic tryptophan fluorescence measurements revealed that protein conformational changes in the presence of sucrose might be at the basis of the observed differences. Another possibility is that the hydrophilic sucrose molecules in the bulk cause the more hydrophobic protein molecules to concentrate at the interface, more so than in water. In conclusion, it is crucial to investigate the foaming of plant protein hydrolysates in media more complex than water, as other non-surface-active food ingredients alter their interfacial behavior.

Impact of ethanol on the air-water interfacial properties of enzymatically hydrolyzed wheat gluten

Studying the air-water (A-W) interfacial characteristics of enzymatically hydrolyzed wheat gluten proteins contributes to understanding their potential as alternatives to animal proteins as foaming agents in food products. In this paper, the impact of the presence of ethanol on the A-W interfacial behavior of gluten hydrolysates (GHs) was studied. Regardless of protein concentration, foaming capacity (FC), i.e. the initial amount of foam formed after a standardized whipping procedure, of four structurally different GHs was higher in a solution containing ethanol than in water. However, the rates of diffusion to and adsorption at the A-W interface of the GH constituents was lower in the presence of ethanol than in water. This suggests that the affinity of the GHs for the interface was lower when ethanol was present, which may be due to ethanol-induced conformation changes in the GH constituents or to some kind of competitive effect due to the surface activity of ethanol. It is hypothesized that the latter effect also contributes to the elevated FC values in the presence of ethanol. The strength of adsorbed GH films was generally lower in a in the presence of ethanol than in water. This was in line with the overall lower foam stability, which is the amount of foam remaining after one hour, of GH solutions containing ethanol compared to that in water. Thus, it is important to take the impact of other food constituents into account when evaluating the potential of plant protein hydrolysates as foaming agents in food systems.

The human digestive tract has proteases capable of gluten hydrolysis

ObjectiveTo identify, purify, and characterize the proteins responsible for glutenase activity in the feces of healthy subjects and patients with celiac disease (CD). MethodsSixteen subjects were included in this study; 8 were healthy with no known food intolerances, and 8 were treated CD patients on a gluten-free diet. Fecal samples were homogenized, and precipitated proteins were purified by chromatography. Glutenase activity was evaluated by bioassays, zymography, and high-performance liquid chromatography with immunogenic 33-mer, 19-mer, and 13-mer gliadin peptides. ResultsThe gastrointestinal elastase 3B (CEL3B), elastase 2A (CEL2A), and carboxypeptidase A1 (CBPA1) enzymes degraded human gluten. These proteins fully hydrolyzed 13-mer and 19-mer gliadin peptides that trigger immune-mediated enteropathy in individuals genetically predisposed to CD and partially digested a 33-mer. Feces from patients with CD showed more glutenase activity than feces from individuals without CD (171–466% higher). Peptidase activity against the gliadin peptides also increased in patients with CD. ConclusionThe digestive tracts of patients with CD and healthy subjects have enzymatic machinery needed for gluten degradation. Patients with CD showed more gluten hydrolysis than did healthy individuals, although, in both cases, a fraction of 33-mer peptide remained intact. Gliadin peptides derived from gastrointestinal digestion, especially the 33-mer, can potentially be used by commensal microbiota from both CD-positive and CD-negative individuals, and differences in bacterial hydrolysis can modify its immunogenic capacity.

Gluten-degrading bacteria are present in the human small intestine of healthy volunteers and celiac patients

Gluten is the only known environmental factor that triggers celiac disease. Several studies have described an imbalance between the intestinal microbiota of different individuals based on diagnoses. Moreover, recent studies have suggested that human bacteria may play an important role in gluten hydrolysis. However, there has been no research focusing on the small intestine.This study aimed to characterize the adult small intestine microbiota possibly implicated in gluten hydrolysis. Duodenal biopsies from different diagnosed individuals were cultured in a gluten-containing medium, and the grown microbiota was analyzed by culture dependent/independent methods. Results showed that gluten-degrading bacteria can be found in the human small intestine. Indeed, 114 bacterial strains belonging to 32 species were isolated; 85 strains were able to grow in a medium containing gluten as the sole nitrogen source, 31 strains showed extracellular proteolytic activity against gluten protein and 27 strains showed peptidolytic activity towards the 33 mer peptide, an immunogenic peptide for celiac disease patients. We found that there are no differences based on the diagnosis, but each individual has its own population of gluten-hydrolyzing bacteria. These bacteria or their gluten-degrading enzymes could help to improve the quality of life of celiac disease patients'.

In-situ and real-time monitoring of enzymatic process of wheat gluten by miniature fiber NIR spectrometer

The degree of hydrolysis (DH), peptide content and angiotensin I-converting enzyme (ACE) inhibitory activity of hydrolysates are the three most important indexes for process control in proteins enzymatic hydrolysis and ACE inhibitory peptides preparation. In this study, a miniature fiber optical spectrometer in conjunction with multivariate analysis for in-situ and real-time monitoring of the parameters (DH, peptide content and ACE inhibitory activity) in wheat gluten (WG) hydrolysis process. Synergy interval partial least square (Si-PLS) algorithm was performed to variables selection and the regression model was calibrated. The performance of a model was evaluated by the correlation coefficient (Rp) and the root mean square error (RMSEP) in the prediction set. The results showed that Rp=0.9270, RMSEP=1.73% for DH; Rp=0.9673, RMSEP=0.79mg/ml for peptide content; Rp=0.9507, RMSEP=5.12% for ACE inhibitory. This work demonstrated that miniature fiber optical spectrometer combined Si-PLS model can be used as an alternative method for in-situ and real-time monitoring the enzymatic process of WG.

Effect of deamidation-induced modification on umami and bitter taste of wheat gluten hydrolysates.

Bitter taste is the main limiting factor for various applications of protein hydrolysates. Frequently used physicochemical methods for debittering protein hydrolysates come with some undesired side effects. Deamidation-induced modification would be a very promising technique to improve the flavor of wheat gluten hydrolysates (WGHs). This study was designed to determine the effect of deamidation with certain enzymes or acid treatment on the chemical composition, bitterness and umami properties of WGHs. The difference between umami peptide and free glutamic acid on the suppression of bitterness is emphatically discussed. The optimal scheme is proposed based on the flavor of WGHs and the yield of peptides. The generation of umami substances suppressed bitter signal transduction. When the content of umami substances was relatively high, the umami-enhancing properties of umami peptides were obviously effective. The intensity of umami taste was high enough to further suppress bitter taste in the course of neurocognitive functioning. When WGHs were treated with Glutaminase for 180 min, the umami taste score increased from 1.62 to 4.27 and the bitter taste score decreased from 1.33 to 0.65. © 2016 Society of Chemical Industry.

The synergistic effect of heat treatment on alcalase-assisted hydrolysis of wheat gluten proteins: Functional and antioxidant properties

In order to confirm the gluten potential for inclusion into functional foods, the synergistic effect of the heat treatment and controlled enzymatic hydrolysis on the functional and the antioxidant properties of alcalase-assisted wheat gluten hydrolysates (AWGHs) will be discussed. For this purpose, wheat gluten was heat-treated during 30 min at 75 °C and intensively hydrolyzed with alcalase at degree of hydrolysis (DH) 16.1%, 22.9%, and 30.2%. All the hydrolysates had excellent solubility over a pH range of 2–12. Emulsifying activity and stability were also improved, while proteolysis was deleterious to foam capacity and stability, water-holding capacity, fat-binding capacity and did not show improvement at higher DH (22.9% and 30.2%). As well, controlled hydrolysis of heat-treated gluten resulted in a remarkable improvement in antioxidant activities. The results show that the heat-treated AWGHs were superior to the untreated hydrolysate in the functional and antioxidant properties tested. Practical applications This report examines existing evidence regarding the wheat gluten proteins (WGP), which is a byproduct from wheat starch processing. It is known that enzymatic hydrolysis is frequently used to improve functional properties of protein hydrolysates and largely dependent on the degree of hydrolysis (DH), which needs to be controlled to elude redundant proteolysis that can deteriorate functionality and cause unfavorable effects. The DH is a substantial factor which affect the hydrolysates' performances and an appropriate selection of protease for WGP hydrolysis will result in maximum biological activity and improved functionalities. Heat treatment is often used to facilitate the proteolysis of proteins. Thus, functional and antioxidant properties of WGP hydrolysates, as a function of heat treatment and the DH were adequately examined in this study and results showed that by combining heat prehydrolysis treatment under controlled conditions, hydrolysates with improved properties can be produced enhancing utilization of WGP in food products.

Exploring the Relationship between Structural and Air-Water Interfacial Properties of Wheat (Triticum aestivum L.) Gluten Hydrolysates in a Food System Relevant pH Range.

The relationship between structural and foaming properties of two tryptic and two peptic wheat gluten hydrolysates was studied at different pH conditions. The impact of pH on foam stability (FS) of the samples heavily depended on the peptidase used and the degree of hydrolysis reached. Surface dilatational moduli were in most, but not all, instances related to FS, implying that, although the formation of a viscoelastic protein hydrolysate film is certainly important, this is not the only phenomenon that determines FS. In contrast to what might be expected, surface charge was not a major factor contributing to FS, except when close to the point-of-zero-charge. Surface hydrophobicity and intrinsic fluorescence measurements suggested that changes in protein conformation take place when the pH is varied, which can in turn influence foaming. Finally, hydrolyzed gluten proteins formed relatively large particles, suggesting that protein hydrolysate aggregation probably influences its foaming properties.

Generation of wheat gluten hydrolysates with dipeptidyl peptidase IV (DPP-IV) inhibitory properties.

Wheat gluten, a Pro-rich dietary protein, was investigated for its potential to produce dipeptidyl peptidase IV (DPP-IV) inhibitory peptides during enzymatic hydrolysis with Debitrase HYW20. Nine gluten hydrolysates (H1-H9) were generated using a 2 factor × 3 level design of experiments (DOE) including the incubation temperature (40, 50 and 60 °C) and the enzyme: substrate ratio (E : S, 0.5, 1.0 and 1.5% (w/w)). Their DPP-IV half maximal inhibitory concentration (IC50) ranged from 0.24 ± 0.02 (H9) to 0.66 ± 0.06 mg mL-1 (H2A and H7) and their degree of hydrolysis (DH) from 31.7 ± 0.9 (H7) to 62.2 ± 3.0% (H6). Gluten and H9, the most potent DPP-IV inhibitory hydrolysate, were subjected to simulated gastrointestinal digestion (SGID), yielding Gluten_CorPP and H9_CorPP, respectively. H9_CorPP had a higher DPP-IV inhibitory potency than Gluten_CorPP (i.e., DPP-IV IC50 values of 0.33 ± 0.03 vs. 1.45 ± 0.26 mg mL-1, respectively). H9 and H9_CorPP both contained relatively potent DPP-IV inhibitory peptides such as Val-Pro-Leu, Trp-Leu and Trp-Pro which were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS). In addition, several sequences possessing features of DPP-IV inhibitory peptides, mostly consisting of a penultimate or C-terminal Pro, were identified within H9. The presence of Pro-containing peptides within H9 may contribute to its stability to digestive enzymes. Gluten hydrolysates may have antidiabetic potential for humans.