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.

Superhydrophobic and Antioxidative Film Based on Edible Materials for Food Packaging.

Significant wastage of the food deterioration in the food preserving process and residual liquid in a container has become a major concern for scientists and the whole society. In this study, an edible multifunctional film integrated superhydrophobicity and antioxidant ability is constructed by chitosan, tea polyphenol, carnauba wax material that is food and drug administration (FDA)-approved for food packaging. The formed edible packaging materials that exhibit great antioxidant property and extremely low water-absorbing quality, was thus proven to display excellent fresh beef preservation effect during storage of 14 days. Importantly, the formed edible multifunctional interface was also demonstrated to perform excellent superhydrophobicity due to the carnauba wax and exhibited large contact angles for various liquid foods, which could effectively reduce the liquid residue. Moreover, the formed edible multifunctional packaging materials showed good thermostability and biocompatibility, which has the potential to be applied as a functional packaging material.

Research advances and application of pulsed electric field on proteins and peptides in food.

Proteins or peptides are essential nutrients required by the human body because some essential amino acids cannot be biosynthesized. In this context, food industry is urged to find method to meet the demands of high protein yield and high bioactive protein/peptide production. Pulsed electric fields (PEF) possess high potential and a promising future in the processing and activity performance enhancement of protein/peptides. PEF processing, as food preservation technology, has ongoing from laboratory and pilot plant scale level to the industrial level, however, there was a lack of knowledge on the effects of PEF on proteins and peptides. In the last few years, the increasing number of studies demonstrated that PEF processing is effective in extracting protein, inactivating most endogenous enzymes in foods, improving peptides' biological activities. We provide an overview of existing and potential applications of PEF on proteins and peptides in food and suggest that the change in structures and functions of proteins/ protein hydrolysates (food component proteins/peptides and enzymes) in PEF processing is receiving considerable attention and may provide a basis for elucidating influence mechanism of PEF processing on protein/peptides and for further improving its application accuracy and range, which thereby could become a key technology for protein-based foods in the future.

Exploration on self-equilibrium rule and adsorption-desorption model between pine nut (Pinus koraiensis) peptide molecules and environmental moisture molecules.

The storage of pine nut (Pinus koraiensis) peptide (PNP) powder involves hygroscopic phenomena. To investigate the adsorption and self-equilibrium rules between these peptides and the environmental moisture molecules, several studies such as low-field nuclear magnetic resonance (LF-NMR), dynamic vapor sorption (DVS) and adsorption-desorption models were done. The results showed that the outward moisture migration occurred during storage as 7.80% and 16.68% moisture were respectively constrained by the original sample and 90 days after lyophilization, by chemical bonding. Additionally, 1.79% moisture was lost in PNP powder at day 90. The optimized adsorption model for PNP powder was changed from Henderson's to Oswin's model during the 90 days' storage whereas the optimized desorption model was changed from Halsey's to GAB's model. The PNP powder at day 90 presented smaller particles with an average diameter and height of 15.645 nm and 50 nm, respectively, and it contained more molecular moisture which cannot be removed. The free thiol of the PNP powder at day 0 and day 90 was 1.75 ± 0.16 µM SH/g and 1.95 ± 0.16 µM SH/g, respectively, and the total sulfhydryl was 101.46 ± 1.06 µM SH/g and 118.44 ± 1.27 µM SH/g. The registered increased sulfhydryl content contributed to the generation of off-flavor.

Tryptophan targeted pulsed electric field treatment for enhanced immune activity in pine nut peptides.

To investigate immune activity of pine nut peptides treated by PEF technology and mechanism of targeting immunoactive sitesits, immune regulatory active was evaluated by RAW 264.7 cells model and the structures of pine nut peptides were researched by fluorescence, CD, and 1D/2D NMR spectrum. These consequences showed the ability of macrophages to phagocytosis neutral red and the production of nitric oxide (NO) were improved after PEF treatment. KWFCT treated by PEF treatment with 40 kV/cm obtained the best immunocompetence. The CD spectroscopy showed that PEF could transform the secondary structures of pine nut peptides. The short-range correlation between Cγ H (1.65 ppm) and Cα H (3.35 ppm), and long-range correlation between Cα H (3.37 ppm) and Nα H (8.07 ppm) were enhanced by PEF treatment. PEF treatment of tryptophan in the pine nut peptides enhanced the immunological activity of the pine nut peptides. PRACTICAL APPLICATIONS: Bioactive peptides derived from food proteins have been extensively studied in recent years. However, little research has been done on the immunoactive peptide of pine nut source. PEF treatment is promising for improving certain properties of foods while maintaining the flavor, color, taste, and nutritional value of the food. This research demonstrated that PEF treatment increased the immunological activity of KWFCT and KWFM. The primary structure of KWFCT and KWFM did not change after PEF treatment, but the secondary structure was transformed into each other. A new perspective on the PEF action site is proposed, which is beneficial to the application of PEF technology.

Intracellular antioxidant activity and apoptosis inhibition capacity of PEF-treated KDHCH in HepG2 cells.

The effect of pulsed electric field (PEF) treatment on the intracellular antioxidant and apoptotic activity of the peptide Lys-Asp-His-Cys-His (KDHCH) was examined using model HepG2 cells. First, PEF treatment conditions specific for the antioxidant peptide were optimized, and it was found that PEF treatment could enhance DPPH, ABTS and hydroxyl radical scavenging capacity of KDHCH. Second, KDHCH subjected to PEF treatment at 1800 Hz and 15 kV/cm was investigated using various intracellular antioxidant assays. PEF treatment decreased the EC50 value and increased the protective ability of oxidative stress inhibition and reactive oxygen species (ROS) scavenging activity of KDHCH. Furthermore, catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and glutathione reductase (GR) activities of KDHCH-pre-treated HepG2 cells increased significantly compared with those of the H2O2 damaged group, whereas lactate dehydrogenase (LDH) and malonaldehyde (MDA) content were decreased. PEF-treated KDHCH exhibited an increased capacity to maintain the stability of mitochondrial membrane potential (MMP) and reduced the level of caspase-3. These results indicate that PEF treatment can enhance the intracellular antioxidant activity of KDHCH, which can inhibit the effect of H2O2 oxidation on HepG2 cells by inhibiting the accumulation of intracellular ROS, regulating antioxidant related enzymes, and blocking the apoptotic mitochondrial pathways activated by ROS.

Characteristic volatiles fingerprints and changes of volatile compounds in fresh and dried Tricholoma matsutake Singer by HS-GC-IMS and HS-SPME-GC-MS.

The present study was to analyze the water dynamics of Tricholoma matsutake Singer during hot air drying by low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI), and to investigate the volatile compounds in the pileus, upper stipe and lower stipe of fresh and dried Tricholoma matsutake Singer by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Fresh samples were dried at 60 °C for 12 h. With the T2i relaxation times decreasing, the water migrated from the inner toward the periphery and then expelled during drying. The characteristic volatiles fingerprints of different parts of fresh and dried samples were established by HS-GC-IMS. The significant differences in volatile compounds were observed among different parts of the fresh sample and C8 compounds (70%-97%) were the principal components. After drying, the concentration of C8 compounds dramatically decreased and some volatile compounds (hexanal, heptanal, 2(5H)-furanone, acetophenone, nonanal, benzeneacetaldehyde) were formed. Thus, hot air treatment affected the volatile compounds in Tricholoma matsutake Singer.