This study investigated the impact of calcium chloride (CaCl2) and magnesium chloride (MgCl2) at varying concentrations on a model milk formulation's physical and chemical properties after thermal treatment. The model milk was subjected to two-stage homogenization and pasteurization before being supplemented with different concentrations of CaCl2 or MgCl2. The findings revealed that elevating the concentration of either calcium or magnesium resulted in the milk emulsion having a higher viscosity and median particle size following heating. CaCl2 had a slightly stronger impact than MgCl2, particularly at higher concentrations. The milk samples also exhibited a reduction in the zeta potential as the ionic strength of the salt solution increased, with the CaCl2-fortified milk displaying a slightly lower negative surface charge than the MgCl2-fortified milk at the same dose. The model milk's viscosity was evaluated after adding various salt concentrations and a temperature ramp from 20 to 80 °C. Notably, the viscosity and particle size changes demonstrated a non-linear relationship with increasing mineral levels, where a significant increase was observed at or above 5.0 mM. An emulsion stability analysis also revealed that the de-stabilization pattern of the high salt concentration sample differed significantly from its low salt concentration counterparts. These findings could serve as a basis for the future development of fortified UHT milk with nutritionally beneficial calcium and magnesium in industrial applications.

Seabuckthorn seed meal (SSM) is a waste of oil extraction industry that rich in protein. In order to seek suitable protein extraction method, three different deep eutectic solvents (DESs) (including choline chloride-glycerol, choline chloride-oxalic acid and choline chloride-urea) were developed for extracting protein from SSM and compared with alkaline. Result indicated that alkaline could effectively extract 56.9% protein from SSM and its protein content was 73.1%, higher than DES at 31.0%41.4% and 64.3%67.5%, respectively. However, compared to alkali, DES led to a product with less β-sheet, more β-turn, more essential amino acids, higher total amino acid content, especially choline chloride-urea which extracted protein showing an integrated and similar protein weight distribution compared to SSM. Also, this protein extracted chloride-urea showed a highest digestibility in vitro (by pepsin) (54.2%). These results indicated that choline chloride-urea extraction is better than alkaline extraction for SSM.

The hypoglycemic activities of the hydrophobic branched-chain amino acid (BCAA) peptides from seabuckthorn seed protein were preliminarily characterized in type 2 diabetic db/db mice. Four novel BCAA peptides (18.27 ± 0.26% (w/w): Leu/Ile-Pro-Glu-Asp-Pro, Asp-Leu/Ile-Val-Gly-Glu, Leu/Ile-Pro, and Leu/Ile-Pro-Leu/Ile) were identified in seabuckthorn seed protein. The protein content in seabuckthorn seed protein hydrolysate, obtained using 80% ethanol, was 78.8 ± 1.4% (w/w). Animal experiments revealed that oral administration of BCAA peptides (all four) significantly reversed the diabetic symptoms. Compared to the db/db group (control), body weight and insulin resistance were ameliorated after treatment with BCAA peptides (0.5, 1.0, 2.0 mg/(g d)). Also, the treatment remarkably reduced the fasting blood glucose (FBG) levels by upregulation of glucose transporter 4 (GULT4). Moreover, BCAA peptides significantly increased the muscle glycogen content (22.6 ± 0.9 nmol/mg) via the downregulation of protein kinase B (AKT) and glycogen synthase kinase-3β (GSK-3β) while increasing the activity of glycogen synthase (GS). BCAA peptides also significantly upregulated the protein levels of phosphatidylinositol 3-kinase (PI3K). We show that BCAA peptides alleviated insulin resistance associated with altered PI3K/Akt protein expression in the skeletal muscle of db/db mice.

The understanding and visualization of dipole-dipole interaction on molecular scale are scientifically fundamental and extremely of interest. Herein, two new zero-dimensional (0D) Mn hybrids with aromatic head groups and alkyl tails as organic spacers are selected as models. It was found that the dipole interaction between head groups and Mn blocks could have a huge impact on their crystalline structures as well as the luminescent properties. The parallel-oriented dipoles of the head groups and MnBr42- blocks contribute to an efficient Förster Resonance Energy Transfer (FRET) in cetylpyridinium manganese bromide ([C16Py]2MnBr4), while the process is absent in 1-methyl-3-hexadecylimidazolium manganese bromide ([C16mim]2MnBr4) with perpendicular-oriented dipoles. This work gives insight into the influence of organic spacers on the geometry and the dipole interaction of Mn polyhedron in the hybrids, which could be of great interest in the future optical regulations and structural design.

This study aimed to utilize an unwanted by-product of soy sauce production, the heat-induced precipitates/sediments (HPSS), to fabricate HPSS nanoparticles using a pH-driven method for their use as nano-carriers of unstable curcumin. The results showed that curcumin could successfully complex with HPSS at pH 6.0, 7.0 and 8.0, via hydrogen bonding, electrostatic interactions and hydrophobic interactions, with high encapsulation efficiency ( > 96%), stability and DPPH radical scavenging activity. Comparable properties were found among the HPSS nanoparticles and derived HPSS-curcumin nanocomplexes obtained at the three pHs, although the HPSS nanoparticles had the highest curcumin loading amount (10.14 mu g/mg) and greatest DPPH radical scavenging power (SC50 0.89 mu g/mL) at pH 7.0, and the nanocomplexed curcumin was most stable at pH 6.0. Thus, HPSS can be utilized as delivery vehicles for hydrophobic substances in food and medicinal applications, and pH is a critical variable governing the outcomes.

Summary In this study, bitter‐tasting hydrophobic peptides were prepared and purified from soy sauce using aqueous ethanol solutions and ion exchange resin, and analysed using RP ‐ HPLC and UPLC ‐Q‐ TOF ‐ MS / MS . Most of bitter fraction from soy sauce was obtained by treatments involving 80% ethanol and subsequent chromatographic separation. This fraction contained sixteen small peptides (molecular weight < 1000 Da; rich in hydrophobic amino acids with Lys‐Pro ( KP ), Glu‐Phe ( EF ), Glu‐Val ( EV ), Asp‐Leu ( DL ), Leu‐Trp ( LW ) and Asp‐Pro ( DP )) capable of enhancing significantly ( P < 0.05) umaminess and/or imparting kokumi effect in taste reconstitution experiments. Thus, the bitter peptides affected bitterness as well as other taste sensations like umaminess, kokuminess and saltiness. This was the first study to report the impacts of the bitter‐tasting hydrophobic peptides on soy sauce and solutions of salt, monosodium l ‐glutamate.

BACKGROUND Two kinds of soy sauce produced via fermentation of the whole soybeans and the defatted soybeans (soy sauce termed 'SSS' and 'SSD', respectively) were subjected to the treatment using aqueous ethanol solutions with high concentrations. Then tasty peptides were separated from SSS and SSD by sensory guided fractionation, using macroporous resin and reverse-phase high-performance liquid chromatography (RP-HPLC), and identified by ultra-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS). Results The result showed that umami-active fractions and <= 3 kDa peptides were mainly concentrated in the supernatants resulted from the treatment with 60% ethanol and the precipitates resulted from the treatment with 80% ethanol. The contents of ammonia nitrogen, non-salt solids, bitter amino acids, amino acids in peptides and the proportion of <= 3 kDa peptides in SSS were higher than those in SSD. Sixteen and fourteen tasty peptides were separated from SSS and SSD, among them five dipeptides (gamma-Glu-Glu, Glu-Glu, gamma-Glu-Cys, gamma-Glu-Leu, Glu-Leu and Ile-Glu) with a glutamic acid residue were identified both in SSS and SSD, which have been reported as umami/kokumi-active peptides in soy sauce. Several peptides identified from SSS (Thr-Gly-Cys, Gly-Leu-Glu, Val-Glu-Ala-Leu and Gly-Gly-Gly-Glu) and SSD (Asp-Arg, Asp-Ala-Glu, Glu-Val-Cys and Gly-Gly-Gly-Glu) are tasty and/or umami-active peptides but have not been reported as tasty peptides in the past. Conclusion Most of the peptides separated from SSD and SSS could impart an umami-enhancing effect on soy sauce, and the marginally more kokumi and bitterness hydrophobic peptides were found in SSS than SSD. (c) 2020 Society of Chemical Industry

This study proposes an industrially feasible approach to handle the heating-induced soy sauce precipitates (SSPs) during soy sauce production. Protein (32.59%; containing a large amount of hydrophobic amino acid) and sugar (26.86%) were found to be the main composition of SSPs, and high content of mineral elements were also discovered in SSPs. A pH adjustment to 8-12 along with an enzymolysis step with alkaline protease seemed beneficial for this purpose while offering opportunities to manipulate the soy sauce quality. The pH adjustment decreased SSPs particle size from micron-scale to submicronor nano-scale, and improved significantly the efficiency of SSPs protein enzymatic hydrolysis and protein recovery (up to 80%). The enzymolysis with alkaline protease enabled the generation of pyrazines while affecting the contents of phenols, alcohols, furans, pyrroles and sulfur-containing compounds. Interactions occurred between amino acids and sugars, among volatiles, and between volatiles (like aldehydes) and other monomers under such alkaline conditions. This study presents an efficient approach that is of practical significance to dealing with SSPs in soy sauce production and reuse of SSPs.

This study was the first to examine the effects of γ-[Glu](1≤n≤5)-Gln (GGP, a taste enhancer; added at 0.5% or 5.0%) on the breadmaking using frozen dough. γ-[Glu](1≤n≤5)-Gln was produced using the method established in our research center. The addition of GGP at either level increased yeast viability, freezable water content and storage and loss moduli, decreased the free sulfhydryl content of dough during the frozen storage and freeze-thaw cycles, and improved the microstructure of frozen dough and texture of the baked bread. The addition of GGP at 0.5% led to a dough having the highest extensibility, and most complete and uniform starch-gluten network, and a baked bread crumb with the lowest hardness, best texture, and most uniform organization. These results indicated that GGP has great potential as a food-derived cryoprotectant/antifreeze agent for the baking industry.

Effects of using high solid concentrations on the synthesis of γ-[Glu](n≥1)-Gln catalyzed by glutaminase from Bacillus amyloliquefaciens were examined in this study. An increment in solid concentration from 10% to 50% (w/w) increased the extent of synthesis of γ-[Glu](n≥1)-Gln, based on the analyses of amino acid composition and amino nitrogen content. Size-exclusion high-performance liquid chromatography analysis revealed an increase in molecular mass of γ-[Glu](n≥1)-Gln resulting from the increase of solid concentration from 10% to 50% (w/w). UPLC-Q-TOF-MS/MS analysis showed that the enzymatic reaction mixtures post γ-glutamyl transpeptidation contained γ-Glu-Gln, γ-Glu-Glu-Gln, γ-Glu-Glu-Glu-Gln, γ-Glu-Glu-Glu-Glu-Gln and γ-Glu-Glu-Glu-Glu-Glu-Gln. The intensity of each γ-[Glu](n=1,2,3,4,5)-Gln produced at a solid concentration of 50% (w/w) was higher than that at 10% (w/w). These findings indicated the potential of such an energy- and water-efficient approach for synthesizing γ-[Glu](n≥1)-Gln at high solid concentrations.

Summary Rice protein is highly nutritive and hypoallergenic but certain physicochemical properties restrict its applications in beverages. This study aimed to tackle this issue by modifying rice endosperm protein with glutaminase via deamidation. Glutaminase treatment facilitated an increase in deamidation degree and mean particle size of rice protein and a continuing decrease in turbidity with time. Favourable changes induced in sensory properties included: improved suspendability (increased by 81.25%), lumpiness (decreased by 84.78%), grittiness (decreased by 72.34%) and overall taste liking (improved by 12.24%). Visual observations of rice protein dispersions and turbidity measurements further confirmed the improved suspendability in water. Fourier transform infrared spectroscopy analysis revealed that the action of glutaminase did not remarkably change the protein structure, but slightly reduced α‐helical conformation whilst increased β‐sheet and β‐turn structures. Glutaminase could be useful for deamidation modification of products with high content of glutamine residues (like rice protein), through inducing the breakdown of some intermolecular and intramolecular bonds including hydrophobic interactions and hydrogen bonding without serious cleavage of the peptide bonds, allowing protein rearrangements to more flexible or extended forms. As a result of protein unfolding with more hydrophobic clusters exposed, certain physicochemical properties of rice protein were improved.

This is the first report on the effect of low temperature stress applied during initial moromi fermentation on the quality and taste of soy sauce. Koji was prepared to yield initial moromi under three comparative fermentation conditions over 9 days: (1) 4 °C and 0% brine (i.e., water) (LTSF); (2) 4 °C and 16% w/w brine (LTSH); (3) 25 °C and 16% w/w brine (the control, CRTH). Greater extent of autolysis in samples was found under low temperature stress conditions (i.e., at 4 °C, a temperature much lower than the normal temperature range like 25 °C for natural microbial growth and performance). Compared to CRTH, LTSF had a two-fold increase of glutaminase activity in dregs and 65.17% increase in supernatant, and after 60 days of moromi fermentation, a 5.73% and 3.47% increase, respectively, in the contents of glutamic acid (Glu) and aspartic acid (Asp). LTSF had the highest total free amino acid content due to both the low temperature stress and absence of salt. The intensity ranking of umaminess and kokumi sensation (LTSF > LTSH > CRTH) revealed by sensory analysis followed the changing trends of their umami and sweet amino acid contents with a trend reversal in the bitter amino acid content. Low temperature (4 °C) without brine for initial moromi fermentation seemed beneficial, leading to a soy sauce product with desired taste and amino acid contents.

This study follows recent attempts to discover and improve the effectiveness of dietary peptides as stimulators of cholecystokinin (CCK) secretion. This study is the first report about the effect of γ-[Glu](n=1,2,3,4)-Trp, produced via γ-glutamylation by glutaminase, on CCK release and Ca2+-sensing receptor (CaS) activation. All these Trp-containing γ-glutamyl peptides exhibited abilities to trigger CCK secretion at 2.5–10 mM, with the highest amount of CCK (187.19 ± 0.68 pg/mL) occurring at 10 mM of γ-Glu-Trp and 5 mM of [Ca2+]e. A CaSR-mediated Ca2+/CaM/CaMK pathway in γ-[Glu](n=0,1,2,3,4)-Trp-induced CCK secretion was proposed based on the following results: the exposure to γ-Glu-Trp increased the protein expression level (Western bolt analysis); The intracellular calcium ([Ca2+]i) mobilization in response to γ-[Glu](n=0,1,2,3,4)-Trp was strongly enhanced; The inhibitors of signaling pathway proteins (NPS-2143, BAPTA-AM and KN62) abolished partially γ-[Glu](n=1,2,3,4)-Trp-induced CCK secretion. Glutaminase-catalyzed γ-glutamylation might be a useful approach for producing superior CCK secretion peptide stimulators.

This is the first research to show that 3-chloro-1,2-propanediol (3-MCPD) was formed upon the action of 0.1% pancreatin at the early stage of soy sauce fermentation with Aspergillus oryzae and mixtures of soy flakes and wheat flour. A series of experiments were then performed to gain insight into such 3-MCPD formation. Results showed that adding 0.1% pancreatin causes slightly decreased reducing sugar content but significantly increased 3-MCPD, without significant changes in amino nitrogen, total nitrogen, and total acid contents. 3-MCPD was formed by the action of different exogenous lipases (pancreatic phospholipase, Candida antarctica lipase B [CALB], and phospholipase A2). Further, soybean oil (not lecithin) could facilitate the 3-MCPD formation upon the action of CALB, phospholipase A2, and pancreatic lipase due to the substrate specificity. Without adding such enzymes, all soy sauce koji with soybean oil had detectable 3-MCPD, indicating that lipase may bind to the substrate via covalent bonding and chloride ions exert nucleophilic attack to form 3-MCPD esters (which were hydrolyzed to release 3-MCPD). Further studies are required to clarify precise mechanisms underlying the 3-MCPD formation in the presence of exogenous lipase especially phospholipases. Practical applications To avoid the prevalence of 3-MCPD brewing in soy sauce, this manuscript gives the theoretical basis.

This study investigated the effect of high solid concentrations on the enzymatic hydrolysis and antioxidant activities of soya bean protein isolate hydrolysates (SPIHs). The soya bean protein isolate at the concentration of 8%, 16%, 24% and 32% was hydrolysed to obtain SPIH with 21.5% degree of hydrolysis (DH), respectively. Results showed that, for the same DH, significant increases in reaction time and decrease in protein recovery were observed as solid concentrations increased. There was no significant difference in molecular weight distribution, but different amino acid compositions in supernatants of SPIH hydrolysed at different solid concentrations. The level of antioxidant amino acids in high solid concentration (32%) was higher than that in low solid concentration group, and antioxidant activity of SPIH increased with the solid concentration increased. Thus, increasing solid concentrations could increase the antioxidant activities and functional properties with low water costs.

Summary A pilot‐scale production of round scad protein hydrolysates via Protamex™‐catalysed proteolysis was firstly established. Process optimisation then focused on the use of mechanical agitation ( MA ) alone or combined with aeration ( MAA ). Comparative examinations revealed that proteolysis involving either MA or MAA was feasible with a hydrolysis degree up to 55%, and individual and total biogenic amine ( BA ) contents much lower than the commonly recognised limits (including the dominant BA , cadaverine). MAA is more advantageous in suppressing bacterial counts and activities associated with protein decomposition, enabling reduced volatile basic nitrogen and BA s. Thus, additional aeration to mechanical agitation is recommended for industrial proteolysis of raw materials unavoidably containing micro‐organisms (especially anaerobic bacteria) in common handling practice.

Soy protein isolate (SPI) was first treated with glutaminase to yield modified SPI (E-SPI) before its complexation with curcumin. Comparisons were made between SPI and E-SPI concerning their characteristics and effectiveness in complexing with curcumin, along with changes in physicochemical properties, 2,2-diphenyl-1-picryhydrazyl (DPPH.)-scavenging capacity and storage stability of curcumin upon complexation. The action of glutaminase did not markedly change SPI structure, but modified some secondary structures, causing greater protein unfolding with more hydrophobic clusters and amino acids exposed. Glutaminase treatment increased DPPH. -scavenging capacity, foaming capacity and stability of SPI. The protein concentration played a role in the changes induced by glutaminase treatment and complexation with curcumin, and 1% protein seemed beneficial (highest DPPH scavenging activity; highest loading amount 10.07%; 98% and > 90% curcumin retained in 1%-E-SPI at 4 degrees C for 2 h and 12 h, respectively). Therefore, glutaminase treatment of SPI before complexation with curcumin appeared to be appropriate.

Summary The influence of protein hydrolysates of salt duck egg white ( PHSDEW ) hydrolysed by acid protease on the quality of Jinga Shrimp ( Metapenaeus affinis ) was analysed. Shrimp immersed in 5% PHSDEW with degree of hydrolysis ( DH 3%) had the highest values of cooking yield, water retention, moisture and texture with the lowest cooking loss when compared to which immersed in 0.4% NaCl, 3.5% mixed phosphates and other PHSDEW with different DH (1%, 2% and 5%) ( P < 0.05). This treatment made muscle fibres retain the most appropriate compact and regular microstructure and improved the thermal stability of shrimp protein as well ( P < 0.05). SDS ‐ PAGE protein patterns revealed shrimp protein would dissolve out during immersion, while only could PHSDEW infiltrate into shrimp muscle. It suggested PHSDEW would be developed as a new type of water retention agent replaced phosphate used in shrimp or other seafoods, which will decrease the waste of salt duck egg white.

The transpeptidase activity of glutaminase from Bacillus amyloliquefaciens (GBA) and Aspergillus oiyzae (GAO) to yield gamma-[Glu](n)-Phe peptides were verified for the first time. In the presence of Gin and Phe, gamma-Glu-Phe and gamma-Glu-gamma-Glu-Phe were synthesized by GAO, and gamma-Glu-Phe, gamma-Glu-gamma-Glu-Phe, gamma-Glu-gamma-Glu-gamma-Glu-Phe, gamma-Glu-gamma-Glu-gamma-Glu-gamma-Glu-Phe, and gamma-Glu-gamma-Glu-gamma-Glu-gamma-Glu-gamma-Glu-Phe were synthesized by GBA. The K-m values for the transpeptidation catalyzed by GBA and GAO were 47.88 and 153.92 mM (Phe as the acceptor), 84.89 and 236.47 mM (gamma-Glu-Phe as the acceptor), indicating that GBA had a greater affinity than GAO for Phe and gamma-Glu-Phe in the transpeptidation reaction. The K-m values for the transpeptidation catalyzed by GBA against acceptors, Phe and gamma-[Glu]((1 <= n<5))-Phe (47.88-206.47 mM), increased with an elevated number of gamma-glutamyl residue within the acceptor. The optimal conditions for gamma-[Glu](n)-Phe synthesis were pH 10 and 37 degrees C for 3 h, 300 mM Gln, 100 mM Phe, 0.05 U/mL GBA. All the gamma-[Glu]((1 <= n<5))-Phe exhibited astringency in water and imparted a kokumi taste to commercial soy sauce and model chicken broth. The astringent threshold values (2.5-3.92 mM) were approximately 3-fold of the kokumi threshold concentrations (0.78-1.53 mM). gamma-[Glu](n)-Phe or the post-enzymatic reaction mixture enhanced the umami intensity of commercial soy sauce and model chicken broth.

The biocatalytic enantioselective reduction of 4-methoxyacetophenone to (S)-1-(4-methoxyphenyl)ethanol was studied.The efficiency of the reaction was improved to different extents when an ionic liquid-containing co-solvent system and an ionic liquids/bufffer biphasic system were used.The catalytic performance of the biocatalyst depended not only on the types of the anions and cations in the ionic liquids but also on their combination.