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This study investigated the relationships among UV-B radiation dose, isoflavone monomers and the oxidative-antioxidant system in germinating soybean. Results showed that the isoflavone monomers content showed a good fit to the quadratic model with UV-B radiation dose, except for aglycones. UV-B decreased phenylalanine content and up-regulated the key enzymes activities in isoflavone biosynthesis. H2O2, electrolyte leakage, malondialdehyde, T22 and M22 were increased, while T23 and M23 decreased. Microscopic analysis showed excess UV-B radiation resulted in the reduced cell volume, irregular cell shape, and increased cell space. The antioxidant enzymes activities were enhanced by UV-B. These results demonstrated that UV-B could trigger the formation of H2O2, resulting in the oxidative stress. Thus, the antioxidant system, including the enzymatic (enhanced the antioxidant enzymes activities) and nonenzymatic (accumulated isoflavones) were activated to minimize oxidative damage. This study provides theoretical basis for enhancing isoflavone monomer accumulation in plant-source foods by UV-B.

To understand the formation of gluten network and its regulation on noodle qualities upon mixing and resting, the dynamic distribution and molecular transformation of gluten were tracked and quantified. Confocal laser scanning microscopy and scanning electron microscopy images showed that appropriate mixing (8 min) and resting (60 min) induced a compact gluten network with higher gluten junctions. Both height and width of protein molecular chains were increased by hydration during mixing and reduced after excessive resting (90 min). According to the size exclusion/reversed phase-HPLC profiles, mixing induced slight depolymerization of large glutenin polymer, and α-gliadin subunits were more susceptible to polymerization after appropriate mixing and resting. Increased mixing time was accompanied by the strengthening of ionic and hydrogen bonds, and the weakening of hydrophobic interaction. PCA and correlation analysis revealed the accurate regulation of mixing and resting induced dynamic distribution and evolution of gluten on the macroscopic noodle qualities.

In this study, the effects of UV-B radiation on the isoflavones accumulation, physiological and nutritional quality, water status, and characteristics of proteins in germinated soybeans were investigated. The results showed that isoflavones content in soybeans increased with appropriate intensity and time of UV-B radiation and decreased with excessive treatment. Fresh weight, length, free amino acids, reducing sugar contents and bulk water (T23) in germinated soybeans decreased with increasing radiation time, indicating that UV-B inhibited the growth and nutrients metabolism of soybean during germination. Cell damage was detected in germinated soybeans with excessive UV-B radiation, as shown by the black spots in cotyledons and the increased intercellular water determined by LF-NMR. Germination resulted in an increase in random coil structures, while UV-B radiation induced no obvious changes in FT-IR spectrum and protein conformation of soybeans. Both UV-B radiation and germination caused the increase in soluble proteins, especially in 1.0–75.0 kDa fraction.

In this study, changes in fresh noodles during storage were evaluated at the physico-chemical, structural, and molecular levels. An increase in TPC and decrease in L(∗) value mostly occurred during the first 24h; the pH value significantly decreased (P

Wheat-based products are staple foods for over a third of the world's population. However, most wheat-based staple foods are provided with a high water content to maintain naturally chewable mouthfeel, which leads to a short shelf life and limits their distribution and marketing. Understanding the fundamental mechanisms and dynamics that drive the quality deterioration is therefore essential for obtaining alternative technologies for optimal quality and extended shelf life. Here, we provide the basis for the physicochemical, structural, and molecular changes occurring in various wheat products during storage, intending to elucidate the underlying deterioration causes. Generally, more desirable qualities are obtained for fresh wheat products, both in appearance and mouthfeel. During storage, changes in the physicochemical properties, structure, main constituents, and water status contribute to the quality deterioration. Based on these changes, deterioration mechanisms are summarized to provide both theoretical and practical references for the quality regulation of high-moisture wheat-based food.

In this study, the improving effects of green tea powder, soluble tea, and tea polyphenols on the mixing and tensile qualities of dough and texture of tea-enriched noodles, as well as the physico-chemical and structural properties of gluten proteins were progressively investigated. Dough strength and noodle texture were significantly increased by all the three tea products. Tea polyphenols in particular presented the most effective improvement with highest dough stability, resistance, and noodle chewiness. SEM indicated that tea products all induced a more developed gluten network, and polyphenol noodle showed the most continuous and ordered structure. FT-IR and fluorescence spectrum indicated that tea polyphenols promoted an enhancement in α-helix structure and the hydrophobic interactions. Tea polyphenols induced the SH/SS interchange during processing and cooking, and enhanced the water-solids interaction in noodles. AFM results showed that polyphenols induced the polymerization of gluten protein molecular chains, with increased chain height and width.

The effects of exogenous spermidine and dicyclohexylamine (DCHA, spermidine synthesis inhibitor) on the antioxidative system and energy status of germinating mung bean were investigated. Results showed that exogenous spermidine increased the content of total phenolic and ascorbic acid and the antioxidative activity, but reduced activities and gene expressions of peroxidase (POD) and catalase (CAT). These changes might be explained by increased H2O2 content and activities of succinic dehydrogenase (SDH), adenosine triphosphatases (ATPases), and cytochrome c oxidase (CCO), resulting in higher adenosine triphosphate (ATP) and energy charge (EC). Interestingly, spermidine down-regulated expressions of SDH, H+-ATPase, Ca2+-ATPase and CCO whilst DCHA reduced energy metabolism and induced the opposite effects to spermidine, except for ascorbic acid content. Inhibition was reversed by exogenous spermidine. In conclusion, spermidine induced the accumulation of H2O2, enhanced the antioxidative system and improved the energy metabolism to enhance the functional quality of mung bean sprouts.

In this study, the inhibiting effects of low-molecular weight polyols on the deterioration of gluten network and noodle texture were systematically investigated, based on dough rheological properties, and the macroscopic, structural and water status changes of gluten protein during storage of fresh noodles. Both glycerol and propylene glycol significantly restrained the decrease of GMP gel weight, LA-SRC value, hardness and springiness, and the increase of cooking loss. SEM showed that polyols retarded the collapse of gluten network, with still continuous gluten fibrils. The inner structure of polyol noodles was much less damaged after 2 days, with more uniform moisture distribution in MRI images. Potential dynamic depolymerization and repolymerization interactions were detected for protein components during processing and cooking, which might contribute to the textural changes. Low-molecular weight polyols inhibited the collapse of gluten network and deterioration of noodle texture although they showed no inhibiting effect on microbial growth.

[6]-Gingerol and [6]-shogaol are the major pungent components in ginger with a variety of biological activities including antioxidant activity. To explore their structure determinants for antioxidant activity, we synthesized eight compounds differentiated by their side chains which are characteristic of the C1-C2 double bond, the C4-C5 double bond or the 5-OH, and the six- or twelve-carbon unbranched alkyl chain. Our results show that their antioxidant activity depends significantly on the side chain structure, the reaction mediums and substrates. Noticeably, existence of the 5-OH decreases their formal hydrogen-transfer and electron-donating abilities, but increases their DNA damage- and lipid peroxidation-protecting abilities. Additionally, despite significantly reducing their DNA strand breakage-inhibiting activity, extension of the chain length from six to twelve carbons enhances their anti-haemolysis activity.

In this study, the effects of UV-B radiation on the isoflavones accumulation, physiological and nutritional quality, water status, and characteristics of proteins in germinated soybeans were investigated. The results showed that isoflavones content in soybeans increased with appropriate intensity and time of UV-B radiation and decreased with excessive treatment. Fresh weight, length, free amino acids, reducing sugar contents and bulk water (T

To optimize antioxidant activity and lipophilicity of cinnamic acid derivatives (CAs) including ferulic acid, sinapic acid, 3,4-dimethoxycinnamic acid, and p-hydroxycinnamic acid, four analogs bearing an additional double bond between their aromatic ring and propenoic acid moiety were designed and synthesized based on the conjugated chain elongation strategy. The antioxidant performance of the CAs were investigated by 2,2'-diphenyl-1-picrylhydrazyl (DPPH)-scavenging, ferric reducing/antioxidant power, cyclic voltammetry, DNA strand breakage-inhibiting and anti-haemolysis activity assays. It was found that CAs with elongation of conjugated chains display increased DPPH-scavenging, DNA strand breakage-inhibiting and anti-haemolysis activities as compared to their parent molecules, due to their improved hydrogen atom-donating ability and lipophilicity. Overall, this work highlights an effective strategy to develop potential CA-directed antioxidants by elongating their conjugated chain.

In this study, changes in fresh noodles during storage were evaluated at the physico-chemical, structural, and molecular levels. An increase in TPC and decrease in L(∗) value mostly occurred during the first 24h; the pH value significantly decreased (P0.05) and proteins were partially depolymerized with the deterioration of fresh noodles, as evidenced by free amino acid determination and SDS-PAGE. Changes were also detected in the pasting and viscosity properties of the starch component. Moreover, the water sorption isotherm of fresh noodles decreased during storage, and the NMR transverse relaxation peak shifted right with an increased peak area between 10 and 100ms. MRI images showed that with increased storage time, the original structure was damaged and water distribution became non-uniform and migrated to the surface. TPC, pH, and L(∗) value were selected as the visualized parameters to characterize the fresh noodle deterioration, based on the correlation and factor analyses.