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A new Aspergillus niger whole-cell catalyst was cultured for the cascade hydrolysis of hesperidin (HES) to produce high-value hesperetin-7-O-glucoside (HG) and hesperetin with high conversion (above 90%). Moreover, the inducers used were shown to be useful for cell growth and to induce cells to produce specific enzymes. Remarkably, the type of inducers determined whether the cells can hydrolyze HES. The product composition was also controllable by adjusting different inducers. Transcriptome analysis suggested that both naringin-vs-blank group and saccharose-vs-blank group had obviously difference in gene expression. The naringin-vs-blank group was mainly up-regulated differentially expressed genes (DEGs), while saccharose-vs-blank group was mainly down-regulated DEGs. The Gene Ontology (GO) analysis showed that whether naringin or saccharose was added as an inducer would greatly affect the catalytic activity of cells. Furthermore, 3 genes related to rhamnosidase, 14 genes related to glucosidase and 5 genes related to hydrolase activity were found. These genes were not only involved in rhamnosidase and glucosidase activities, but also spliceosome and the sucrose and starch metabolic pathways. The quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the results of transcriptome sequencing were reliable. This study gave a new approach to hydrolyze HES, and new perspectives to understand the mechanisms associated with the hydrolysis of whole-cell catalyst., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Cronobacter sakazakii is a common foodborne pathogen that can tolerate various stress conditions. Acidic environment is a common stress condition encountered by bacteria in food processing and gastrointestinal digestion, including both inorganic and organic acids. In order to elucidate the Acid Tolerance Response (ATR) of C. sakazakii, we performed high-throughput RNA-seq to compare gene expression under hydrochloric acid and citric acid stresses. In this study, 107 differentially expressed genes (DEGs) were identified in both acids, of which 85 DEGs were functionally related to the regulation of acid tolerance. Multiple layers of mechanisms may be applied by C. sakazakii in response to acid stress: Firstly, in order to reduce excessive intracellular protons, C. sakazakii pumps them out through trans-membrane proteins or consumes them through metabolic reactions. Secondly, under acidic conditions, a large amount of reactive oxygen species and hydroxyl radicals accumulate in the cells, resulting in oxidative damage. C. sakazakii protects cells by up-regulating the antioxidant stress genes such as soxS and madB. Thirdly, C. sakazakii chooses energy efficient metabolic pathways to reduce energy consumption and maintain necessary processes. Finally, genes involved in chemotaxis and motility were differentially expressed to respond to different acidic conditions. This study systematically analyzed the acid-resistant mechanism of C. sakazakii under the stress of organic and inorganic acids, and provided a theoretical basis for better control of its contamination in food., Competing Interests: Declaration of Competing Interest The authors declared that there is no conflict of interest., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Lipid stability, physical properties and volatiles profile of vacuum-packaged fresh Atlantic salmon (Salmo salar) loins were evaluated after hyperbaric storage at low temperature (HS/LT: 60 MPa/10 °C) and compared to atmospheric pressure and conventional refrigeration (AP/5 °C) after 5, 15 and 30 days, and at low temperature (AP/10 °C), after 5 and 15 days. No variations in drip loss and water holding capacity were observed for HS/LT samples. Compared to AP, HS/LT caused lower changes on muscle fibres, visible by scanning electron micrographs, and a decrease of resilience property (only after 30 days). In addition, myofibrillar fragmentation index did not change at HS/LT. Fatty acids were generally not affected by the different storage conditions, while the polyene index at HS/LT was similar to fresh samples during the 30 days of storage, confirmed by the lower lipid oxidation state of these samples, compared to AP. According to the volatile profile (SPME-GC/MS), HS samples showed to be more similar to the fresh ones, retaining fresh-like alcohols and aldehydes, generally not detected in AP samples after 15 days, the latter presenting spoilage-related compounds probably derived from microbial activity. According to these results, HS/LT represents a promising preservation methodology for fresh salmon loins (and fish in general), retaining better important physicochemical properties for 30 days, when compared to the conventional refrigeration., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The understanding of the interactions between starch and cellulose hydrocolloids is crucial for equipment design and definition of operation parameters in the food industry. In the present study, the possible interactions of wheat starch (WS) with different levels (2-10%) of carboxymethyl cellulose (CMC) or microcrystalline cellulose (MCC) in short-term retrogradation were explored by dynamic rheological and Fourier transform infrared spectrum (FTIR) measurements. The chains of water-soluble CMC could creep into the continuous phase during paste gelation. It was found the amylose network structure was broken and the inter- and intra-molecular hydrogen bond of WS were weaken after gelation. Moreover, there were interactions between the chains of CMC and chains of amylose at higher CMC concentration. On other hand, water connected with COO - groups blocked the interactions between CMC chains and amylose, and the interactions among CMC chains. The amorphous phases of high crystalline MCC were just swollen during paste gelation. It results that heterogeneous microstructure with amylose and MCC domains unevenly distributed was in WS/MCC paste., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

This study seeks to clarify and determine the fundamental properties of N-terminal domain of high molecular weight glutenin subunits (HMW-GS) 1Dx5 (1Dx5-N). 1Dx5-N was expressed in E. coli and its solubility was measured by spectrophotometry. Effects of edible salts (NaCl, Na 2 CO 3 ), disulfide bond reductant dithiothreitol (DTT) and hydrophobic interactions of denaturant sodium dodecyl sulfonate (SDS) on 1Dx5-N polymer were investigated by native polyacrylamide gelelectrophoresis (PAGE), nonreducing/reducing SDS-PAGE, intrinsic fluorescence, size exclusion chromatography (SEC), dynamic light scattering (DLS) and circular dichroism (CD). Results showed that 1Dx5-N formed a soluble aggregate in aqueous solutions by native-PAGE, clarifying the role of N-terminal of HMW-GS in the insolubility of the whole subunits. Meanwhile, the hydrophobic interaction was more potent in promoting the aggregation of 1Dx5-N in aqueous solutions from the results of SEC, DLS and CD. Edible salts, NaCl and Na 2 CO 3 , could improve the polymer formation of 1Dx5-N through disulfide bonds. Moreover, Na 2 CO 3 at high concentrations (>200mM) greatly favored polymer formation by disulfide bonds, and it induced other types of cross-links between amino acids in 1Dx5-N according to nonreducing/reducing SDS-PAGE and fluorescence spectrum. Moreover, the formation of covalent bonds was reinforced by hydrophobic interactions between 1Dx5-N. Therefore, these results provide much novel information on the N-terminal domain of HMW-GS to facilitate the understanding of its functional properties in wheat flour., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The objective of the present study was to detail the change of 4(5)-Methylimidazole (4-MI) in sulfite and sulfate reactions with different initial pH values. Glucose/ammonium sulfate and glucose/ammonium sulfite reaction systems with initial pH conditions 4.9, 5.9, 6.9, 8.0 and 8.6, were heated at 100°C for 2h, respectively. Higher concentration of methylglyoxal (MGO) and 4-MI was detected in thermal treated glucose/ammonium sulfite reaction system than that in sulfate system. The SO 3 2- reacting with MGO and other precursors of 4-MI at higher pH conditions prevented 4-MI formation. However, no inhibition of 4-MI was found at lower pH conditions due to higher reactivity of the nucleophilic NH 4 + than SO 3 2- . The browning intensity of the sulfite system changed scarcely at higher pH values, which was possibly caused by the polyreaction between SO 3 2- and carbonyl, instead of the intermolecular polymerisation of carbonyl in the advanced stage of the Maillard reaction., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

DPPH assay is widely used to evaluate the radical scavenging activities of peptides. Effects of pH and buffers on the stability of DPPH• and its reduced product (DPPHH) in the ethanol-buffer solution were investigated in this study and the reactivity of DPPH• towards several dipeptides was compared to that of 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS• + ) and the peroxyl radicals in oxygen radical absorbance capacity (ORAC) assay. Results showed that the deprotonation of DPPHH under basic condition could interfere with the spectrophotometric measurement at 515-525nm. It was suggested that the reaction mixture be maintained at a final pH range of 5.0-6.5 in 1:1 ethanol-acetate/citrate buffer medium when evaluating the activities of peptides. Additionally, among tested dipeptides, only Cys-containing dipeptides displayed DPPH• scavenging activity with 0.14-0.28μmol TE (Trolox equivalent)/μmol, while Tyr/Trp-containing dipeptides with high reactivity towards ABTS• + and peroxyl radicals were inert to DPPH• with TE values less than 0.02., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Soy protein isolate (SPI) can act as effective nanocarriers for water-insoluble curcumin, however, the maximal capacity of this protein to load curcumin and molecular mechanism for the formation of the nanocomplexes are still little known. This work investigated the formation and properties of SPI-curcumin nanocomplexes formed at a low concentration of 0.05% (w/v), as well as the influence of a high intensity ultrasonic treatment on the nanocomplexation. Most of the particles in non- or ultrasonic-treated SPIs were present in nanoparticle form with z-average sizes of about 50-52nm. The load amount (LA) of curcumin in the non-treated nanocomplexes reached 103.9μg/mg SPI. The ultrasonic treatment of the protein solution further significantly increased the LA, while the LA was considerably decreased by the treatment after the nanocomplexation. The complexation with curcumin significantly increased the particle size and ζ-potential of both non- and ultrasonic-treated SPIs, but led to a considerable reduction in surface hydrophobicity, with the greater changes observed for ultrasonic-treated SPI. The nanocomplexation with SPIs remarkably improved the storage stability of curcumin, with much better improvement observed for the ultrasonic-treated SPI. Both the number and nature of hydrophobic sites are important for the nanoparticles in SPI to exhibit high capacity to load curcumin molecules. This study confirmed that SPI exhibited a high capacity to load water-insoluble curcumin, and an ultrasonic pretreatment could further improve its encapsulation efficiency and stability of curcumin., (Copyright © 2015. Published by Elsevier Ltd.)

An enzymatic hydrolysis approach was proposed for the preparation of bioactive hydrolysate of scorpion Buthus martensii Karsch (BmK) protein. Results showed that the anticoagulant activity of the hydrolysates of BmK protein was closely related to both the enzyme type and the degree of hydrolysis. Alcalase AF showed to be the best enzymes for the hydrolysis. And the hydrolysis degree (DH) was closely related with the anticoagulant activity of the hydrolyzate. At a DH value of 18% with Alcalase AF, the hydrolyzate exhibited the highest activity. The hydrolysate was then separated and purified by consecutive chromatographic procedures, giving a novel anticoagulant peptide consisting of ten amino acids (MW: 1119.8Da) with its sequence of Val-Glu-Pro-Val-Thr-Val-Asn-Pro- His-Glu identified by MALDI-TOF/TOF MS. The negatively charged amino acids and hydrophobic amino acids may contribute to the anticoagulant activity of the prepared peptides. And the Val residue in N-terminal was also critical for the anticoagulant activity of the BmK peptide. Furthermore, the anticoagulant activity kept stable after in vitro digestive simulation. This research provided a promising bioprocessing route for production of anticoagulant peptides using BmK protein as a potentially valuable bioresource., (Copyright © 2014 Elsevier Ltd. All rights reserved.)