The separation and identification of the residual antigenic fragments in soy protein hydrolysates

Conformation-Activity Mechanism of Alcalase Hydrolysis for Reducing In Vitro Allergenicity of Instant Soy Milk Powder

Effective reduction of the allergenicity of instant soy milk powder (ISMP) is practically valuable for expanding its applications. This study optimized the enzymolysis technology of ISMP using single-factor experiments and response surface methodology, combined serological analysis, cellular immunological models, bioinformatics tools, and multiple spectroscopy techniques to investigate the effects of alcalase hydrolysis on allergenicity, spatial conformation, and linear epitopes of ISMP. Under the optimal process, special IgE and IgG1 binding abilities and allergenic activity to induce cell degranulation of alcalase-hydrolyzed ISMP were reduced by (64.72 ± 1.76)%, (56.79 ± 3.72)%, and (73.3 ± 1.19)%, respectively (P < 0.05). Moreover, the spatial conformation of instant soy milk powder hydrolysates (ISMPH) changed, including decreased surface hydrophobicity, a weaker peak of amide II band, lower contents of α-helix and β-sheet, and an enhanced content of random coil. Furthermore, the linear epitopes of major soy allergens, 9 from glycinin and 13 from β-conglycinin, could be directionally disrupted by alcalase hydrolysis. Overall, the structure-activity mechanism of alcalase hydrolysis to reduce ISMP allergenicity in vitro was preliminarily clarified. It provided a new research direction for the breakthrough in the desensitization of ISMP and a theoretical basis for revealing the potential mechanism of alcalase enzymolysis to reduce the allergenicity of ISMP.

Relation of amino acid composition, hydrophobicity, and molecular weight with antidiabetic, antihypertensive, and antioxidant properties of mixtures of corn gluten and soy protein hydrolysates

New mixed Alcalase-hydrolysates were developed using corn gluten meal (CP) and soy protein (SP) hydrolysates, namely CPH, SPH, SPH30:CPH70, SPH70:CPH30, and SPH50:CPH50. Amino acid profile, surface hydrophobicity (H 0), molecular weight (MW) distribution, antioxidant activity, angiotensin-converting enzyme (ACE), α-amylase, and α-glucosidase inhibitory activities, and functional characteristics of hydrolysates were determined. Hydrolysis changed the amount of hydrophilic and hydrophobic amino acid composition and significantly increased the H 0 values of hydrolysates, especially for CPH. The DPPH radical scavenging activity (RSA) was higher for CPH, SPH30:CPH70, and SPH50:CPH50 than SPH and SPH70:CPH30. Moreover, SPH, SPH70:CPH30, and SPH50:CPH50 showed lower MW than CPH, and this correlated with the higher hydrophilicity, and ABTS and hydroxyl RSA values obtained for SPH and the mixed hydrolysates with predominantly SPH. SPH70:CPH30 exhibited higher ACE, α-glucosidase, and α-amylase inhibitory activities among all samples due to its specific peptides with high capacity to interact with amino acid residues located at the enzyme active site and also low binding energy. At 15% degree of hydrolysis, both SPH and CPH showed enhanced solubility at pH 4.0, 7.0 and 9.0, emulsifying activity, and foaming capacity. Taken together, SPH70:CPH30 displayed strong antioxidant, antihypertensive, and antidiabetic attributes, emulsifying activity and stability indexes, and foaming capacity and foaming stability, making it a promising multifunctional ingredient for the development of functional food products.

Allergenicity Alleviation of Bee Pollen by Enzymatic Hydrolysis: Regulation in Mice Allergic Mediators, Metabolism, and Gut Microbiota

Bee pollen as a nutrient-rich functional food has been considered for use as an adjuvant for chronic disease therapy. However, bee pollen can trigger food-borne allergies, causing a great concern to food safety. Our previous study demonstrated that the combined use of cellulase, pectinase and papain can hydrolyze allergens into peptides and amino acids, resulting in reduced allergenicity of bee pollen based on in vitro assays. Herein, we aimed to further explore the mechanisms behind allergenicity alleviation of enzyme-treated bee pollen through a BALB/c mouse model. Results showed that the enzyme-treated bee pollen could mitigate mice scratching frequency, ameliorate histopathological injury, decrease serum IgE level, and regulate bioamine production. Moreover, enzyme-treated bee pollen can modulate metabolic pathways and gut microbiota composition in mice, further supporting the alleviatory allergenicity of enzyme-treated bee pollen. The findings could provide a foundation for further development and utilization of hypoallergenic bee pollen products.

The Conformational Structural Change of Soy Glycinin via Lactic Acid Bacteria Fermentation Reduced Immunoglobulin E Reactivity

This study investigated the fermentation of isolated soy glycinin by using the Lactiplantibacillus plantarum B1-6 strain, its reduction effect on immunoglobulin E (IgE) reactivity, the relationship with protein aggregation/gelation state and conformational changes. Fermentation was performed under different glycinin concentrations (0.1%, 0.5%, 1% and 2%, w/v) and varied fermentation terminal pH levels (FT-pH) (pH 6.0, 4.5, 4.0 and 3.5). L. plantarum B1-6 showed potency in reducing immunoreactivity to 0.10–69.85%, as determined by a sandwich enzyme-linked immunosorbent assay. At a FT-pH of 6.0 and 4.5, extremely low IgE reactivity (0.1–22.32%) was observed. Fermentation resulted in a great increase (2.31–6.8-fold) in particle size and a loss of intensity in A3 and basic subunits. The conformation of glycinin was altered, as demonstrated by improved surface hydrophobicity (1.33–7.39-fold), decreased intrinsic fluorescence intensity and the α-helix structure. Among the four selected concentrations, glycinin at 1% (w/v, G-1) evolved the greatest particles during fermentation and demonstrated the lowest immunoreactivity. Principal component analysis confirmed that particle size, intrinsic fluorescence intensity, α-helix and ionic bond were closely related to immunoreactivity reduction.

Reducing the allergenicity of pea protein based on the enzyme action of alcalase

Enzymatic hydrolysis could be one of the crucial means to limit the allergenicity of allergens. The allergenicity of pea peptides was evaluated using indirect ELISA and RBL-2H3 cell assay, thereby obtaining hypoallergenic pea peptide sequences. Results indicated that pea protein-sensitized mice produced higher levels of total IgG1 and IgE antibodies than the mice in the control group (P < 0.05). Moreover, the allergenicity of hydrolysates decreased significantly after enzymolysis, and the allergenicity of ultrafiltration component F1 and purified component F1-2 was significantly lower than that of other isolated and purified components (P < 0.05). Furthermore, ADLYNPR identified from F1-2 had lower binding capacity to specific IgE and IgG1 and lower degree of cell degranulation with a higher EC50 value of 6.63 ng mL-1, which was about 36.83 times that of pea protein (P < 0.05). Based on the above results, ADLYNPR might be a potential source of hypoallergenic peptides.