Mung bean sprouts turn brown during cold storage. Here, we cloned polyphenol oxidase (PPO) mRNA, and then examined its expression and active form to clarify the mechanism of this browning. A PPO cDNA encoding 592 amino acids showed high homology to PPO genes of Fabaceae plants and had highly conserved motifs, including the active site and transit peptide to the plastid thylakoid. Expression of PPO mRNA was almost constant. The translated PPO protein was considered to migrate into the thylakoid, but the active PPO was mainly present in the cytosol or soluble fraction, and its molecular mass was 31 kDa, smaller than the translated protein. The membrane structure of mung bean sprouts is heavily disrupted during cold storage. These results showed that PPO transported into the thylakoid is solubilized and decomposed to its active form, which oxidizes phenolic compounds in the cytosol to turn sprouts brown during cold storage.
This study aimed to evaluate the protective effect of methanol extract of perilla seed meal (PSE) against oxidative stress induced by tert-butylhydroperoxide (t-BHP) in HepG2 cells. The total phenolics and flavonoid contents of PSE were 41.36 ± 1.00 mg gallic acid equivalents/g of residue and 38.20 ± 0.17 mg catechin equivalents/g of residue, respectively. Quantitative analysis of the major constituent phenolic acids and tocopherols was achieved by using high-performance liquid chromatography. PSE (10–100 µg/mL) pretreatment significantly prevented t-BHP-induced cytotoxicity in HepG2 cells. Oxidative damage induced by t-BHP was accompanied by glutathione depletion, ROS generation, and lipid peroxidation, which were all significantly ameliorated by PSE. The cytoprotective effect of PSE was attributed to the modulation of cellular antioxidant defense enzymes such as glutathione peroxidase, superoxide dismutase, glutathione reductase, and catalase. Collectively, the bioactive compounds of PSE were able to prevent oxidative stress through the enhancement of the antioxidant indices.
This work evaluated the extrusion, steam explosion and enzymatic hydrolysis on the physical and chemical properties of wheat bran. At the same particle size, the three treatments effectively improve the water holding capacity and swelling capacity of wheat bran. Among them, steam exploded wheat bran had the highest water holding capacity and swelling capacity, followed by extruded wheat bran. All the three treatment have a weakened effect on sodium cholate adsorption capacity, cation exchange capacity and phytate content of wheat bran. Compared with enzymatic hydrolysis, steam explosion and extrusion have a stronger impact on these indexes. Moreover, water holding capacity, swelling capacity, L* value, sorption capacity of sodium cholate, cation exchange capacity and phytate content of decreased with the decrease of particle size of bran. In the range of 450–150 µm, the particle size had a significant effect on the physical and chemical properties of bran. Therefore, extrusion and steam explosion are highly potential for use as new treatment methods on wheat bran.
The purpose of this study is to examine the feasibility of element fingerprints in identifying the geographical origin of Fenghuangdancong and other Chinese tea. A total of 45 elements were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Element fingerprints were established by transferring element composition into graphs. Similarity degrees of element fingerprints and linear discriminant analysis were performed in order to identify tea samples according to their origin. The analysis revealed a satisfactory separation of tea samples according to their origin with 93.3 % classifications rate of similarity degrees and 96.6 % predictive ability of the cross-validation of linear discriminant analysis. There is small difference between each other. The analysis indicated element fingerprints could be used to identify the authenticity of Fenghuangdancong tea.
This study aimed to evaluate the synergistic effects of nisin combined with cinnamaldehyde (Nis+Cin) and nisin combined with carvacrol (Nis+Car) on food-borne bacteria. The minimum inhibitory concentrations for Nis, Cin and Car ranged from 2,500 to 10,000 IU/mL, 0.78–6.25 mg/mL and 0.78–3.13 mg/mL, respectively. Nis+Cin displayed a total synergism against all test bacteria, showing a marked release of bacterial intracellular constituents. In a food model, high protein concentration, low starch and oil concentration as well as low pH, positively influenced the antimicrobial activity. Moreover, in sandwich spread, Nis+Cin enhanced the inhibition of S. typhimurium at the greatest level by reducing cell numbers by more than 4 log CFU/g from 6 days of storage. These results suggest that the dose used for each antimicrobial compound can be minimized by combination, thereby decreasing the possibility of antimicrobial resistance and also reducing food processing costs.
In general, giant embryo rice has a lower germination rate and shows non-uniformity in seedling emergence. We attempted to determine suitable pH and temperature conditions for germinating the giant embryo rice cultivar Koshiguruma, grown in Niigata Prefecture, in combination with red onion extract. We also examined metabolic changes in the grains that could have important human health benefits. Koshiguruma showed a higher germination rate (1.1 times) when germinated with red onion extract for 24 h at 37 °C and contained more gamma aminobutyric acid (1.7 times) than when germinated with water. In addition, germination of Koshiguruma in combination with polyphenols imparted antioxidant capacities. Thus, we have established methods for improved cultivation of giant embryo rice, which may have important human health benefits upon consumption.
We evaluated cycloalliin, a sulfur-containing imino acid found in garlic and onion, for its possible use as an ingredient in cosmetics. The activity of tyrosinase, an enzyme involved in melanin synthesis, was inhibited by cycloalliin in a dose-dependent manner. Cycloalliin was also found to be a mixed-type inhibitor of the monophenolase and diphenolase activities of tyrosinase with Ki values of 56.0 mM and 13.6 mM, respectively. In addition, cycloalliin only weakly inhibited the activity of mushroom tyrosinase. Furthermore, cycloalliin significantly reduced α-melanocyte-stimulating hormone-induced melanin levels and both protein and mRNA levels of tyrosinase in B16 mouse melanoma cells at a final concentration of 3.8 µM. Cycloalliin also significantly inhibited the activity of adenylate cyclase, an enzyme involved in the cyclic adenosine monophosphate-signaling pathway during melanogenesis, and consequently mRNA and protein expression of tyrosinase was reduced significantly. These results show that cycloalliin may be useful as a skin-lightening agent in the cosmetics industry.
Metabolic changes of Tan sheep meat maintained at 0 °C for up to 8 d were identified based on gas chromatography time-of-flight mass spectrometry. Total viable counts (TVC), total volatile basic nitrogen (TVB-N) and pH were utilized as freshness indicators during meat storage. A relationship between meat freshness, metabolite accumulation and key metabolic pathways was postulated. Twenty-seven statistically significant metabolites were characterized. D-glyceric acid, phenylalanine, methionine, glucose-1-phosphate, D-(glycerol-phosphate), lysine, ribitol, asparagine and isomaltose were significantly (p < 0.01) correlated to the freshness indicators. A correlation coefficient with gluconic acid, citric acid and trans-4-hydroxy-L-proline and the freshness indicators ranged from 0.539 to 0.911. 1, 5-anhydroglucitol was significantly correlated with pH (p < 0.05) and TVC (p < 0.01). These metabolites were identified as potential spoilage biomarkers. Three major metabolic processes occurred during storage: metabolism of alanine, aspartate, and glutamate; an operational TCA cycle and metabolism of amino sugar and nucleotide sugar.
A fine waxy rice starch solution was spray-dried as a wall material for microencapsulation. For this process, the primary solution of mixed core and wall materials needs a low viscosity. Low molecular weight polysaccharides have been commonly used as the wall material. In the present study, a starch solution prepared hydrothermal process at 100 °C and fine starch solutions prepared by compressed hot water process at 140, 160, and 180 °C were investigated. The compressed hot water process reduced the viscosity of the fine starch solution and its particle size to produce a uniformly fine spray-dried powder. Finally, inulin hydrolysate including difructose anhydrides (DFAs) were microencapsulated by spray-drying. Previously, preparing inulin hydrolysate powder through spray-drying and freeze-drying has been difficult because it adheres to the inside surface of the drying chamber. Microencapsulation of inulin hydrolysate using a 160 °C fine starch solution as the wall material produced powder efficiently and enhanced its handling properties.
In the present study, sheep plasma (SP) was hydrolyzed with 5000 U alcalase/g protein at 45 °C, pH 11 for 6 hours to prepare sheep plasma hydrolysate (SPH). The effects of SPH on meat color stability and oxidation of lipid and proteins were evaluated in mutton patties. Data obtained showed that addition of 2 % SPH significantly improved the redness (a* value) of mutton patties in storage (P < 0.05), which was comparable to 0.05 % vitamin C. At the same time, 2 % SPH effectively inhibited metmyoglobin formation and oxidation of lipid and proteins in mutton patties. The inhibition of oxidation in meat by SPH was concentration dependent. In summary, this study showed that SPH was antioxidant and 2 % SPH could be used in production to prevent quality deterioration of meat products in storage, providing a new way for high-value utilization of sheep blood.
This study aimed to characterize the crude enzyme from Hericium erinaceum (H. erinaceum) as a substitute source of rennet and assess its proteolytic behavior on bovine caseins. The crude enzyme from H. erinaceum was active in the pH range from 3.7 to 6.5 and was inactivated completely by heating at 45 °C for 15 min. The use of specific inhibitors revealed that the crude enzyme from H. erinaceum contains an aspartic protease with an optimum temperature of 30–35 °C. The addition of CaCl2 enhanced the milk-clotting activity of the enzyme. A comparison of SDS-PAGE and kinetic properties of the crude enzyme from H. erinaceum with chymosin on bovine caseins showed that αs- and β-caseins were preferentially degraded relative to κ-casein.
The results indicate that crude enzyme from H. erinaceum can be used as an effective coagulant in cheesemaking.
The aim of this study was to describe the effect of oleosins on the stability of oil bodies in the production of soymilk. We investigated the protein content, average particle diameter and SDS-PAGE analysis of oil bodies at different stages of the soymilk manufacturing process. N-terminal sequencing analysis showed that 11-kDa and 9-kDa fragments, which were not digested by papain, were present at the hydrophilic C-terminal domains of the 24-kDa oleosin and did not undergo decomposition. In terms of colloidal stability, oil bodies from soybeans had the highest floating rate. The binding of oleosin and soymilk proteins was shown to play a role in colloidal stability, especially in solutions with less than 2.5 mg/mL protein. Using transmission electron microscopy, it was found that the surface of the oil bodies was coated in proteins, increasing their stability.
Using HPLC, it was demonstrated that the major free phenolic compound in the pericarp and seed coat of red rice was cyanidin, which belong to anthocyanidin glucoside, exist only in the episperm of red rice as content of 1.64±0.10 mg/g. Anthocyanidin glucoside play a significant role in eliminating free radicals and reacting oxygen species (ROS) to prevent cellular oxidative stress. However, the chemical stability of anthocyanidin glucoside has been one of the major drawbacks for health applications. For longer storage, our results showed that red rice anthocyanidin glucoside could be stored with 0.3 % Vitamin C or 0.5 % NaHSO3, and be protected from light, high temperature, high pH and metal ions in environment. Antioxidant activity verified that anthocyanidin glucoside performed better than Vitamin C in ferrous ions chelating activity, scavenging activities for hydroxyl and DPPH radicals. Overall, the red rice might be used as a natural antioxidant supplement applying medical treatments in future days.
The chickpea sourdough, also known as “sweet yeast”, has not been experimented in chemically leavened bakery products such as cake so far, although it has been used in traditional breads. The aim of this study was to optimize the amounts of chickpea sourdough (A) and baking powder (B) in cake formulation and by examining various quality parameters. An experimental design suggested by Response Surface Methodology, Central Composite Design was used for optimization. The optimization results were validated experimentally. The cake, produced according to the optimized model (OC) was compared with the control cake (CC) in terms of various quality parameters. According to the results, optimum levels of usage were 64.02 g for A and 5.97 g for B. Smaller and more homogeneous pore structures were obtained in OC texture by the use of A according to the image analysis. The cake also acquired slightly sour, sweetish and soft sensory profiles. DPPH radical scavenging activity and physicochemical properties were also improved by the use of the chickpea sourdough.
Semi-dry fermented sausages containing two levels of sugary kefir grains (5 %, 7.5 %) and brown sugar (4 %, 6 %) were produced and the quality attributes were evaluated. Following fermentation and heating, sausages contained 14–15 % fat. No differences (P > 0.05) were observed in CIE a* for all treatments, but significantly higher CIE L* for KB1 (4 % brown sugar/5 % sugary kefir grains) than other treatments was found. KB4 (6 % brown sugar/7.5 % kefir grains) had significantly higher (P < 0.05) textural fracturability and chewiness than KB1 and KB3 (6 % brown sugar/5 % kefir grains), and KB4 and KB3 were higher in shear force value than others. Total plate counts (TPC) of all treatment were not higher than 105 cfu/g after 12 weeks. Untrained affective evaluation showed that KB2 treatment received 49 % (total of 300 consumer ballots) of high score (11–15) ballots, followed by KB4 of 37.7 %. Results demonstrated good microbial stability and acceptable quality of semi-dry fermented sausages containing sugary kefir grains.
The deer bone peptides (DBP) was used to chelate with Ca2+ to form the deer bone peptides chelated calcium (DBPCC), which could be a calcium nutraceutical supplement. The optimal condition for the chelation reaction was that 1.535 mg mL−1 DBP reacted with 7.5 mmol L−1 CaCl2 at pH 7.0 and 40 °C for 15 min. Negatively charged amino acids, positively charged amino acids and hydrophobic amino acids in the DBPCC were probably important to the chelation reaction. And the DBP could chelate with Ca2+ through metal-binding sites (carboxyl oxygen atoms and amino nitrogen atoms). The Ca2+ would cause the DBP folding and conformation modification. Furthermore, the DBPCC was stable under ileum conditions (pH 7.0, 37 °C), indicating that it would be well absorbed in the human body and had the potential to improve the traditional calcium nutrition fortifier.
In this research, a nonlinear model describing the relationship between the inoculation fermentation parameters and the quality of yin rice were investigated based on artificial neural network and genetic algorithm (ANN-GA) model. The ANN-GA model had excellent potential for predicting the viscosity property of yin rice, and fermentation parameters were optimized by using genetic algorithm. Through ANN-GA model, the optimized inoculation fermentation parameters were: 0.05 % lactic acid bacteria, 0.05 % Saccharomyces cerevisiae, 0.2 % Rhizopus oryzae, then fermenting for 48 h at 25 °C. The results were further validated by experiments. Moreover, it revealed that inoculation fermentation not only effectively improved physico-chemical characteristics of yin rice, but also shorten period of fermentation about 14 days compared to the natural fermentation. These results indicated that the accuracy and reliable of fermentation parameters optimized by ANN-GA model.
Application of high-speed shear treatment (HST) to gelatinized high-amylose rice created rice gels with unique viscoelastic properties. This study examined the quantitative relationship between HST conditions and texture, assessing the dynamic viscoelastic properties of high-amylose rice gels based on a second-order polynomial model. Twenty-four HST high-amylose rice gel samples were prepared by varying the three conditions of shearing speed and time, and temperature during HST. Dynamic viscoelasticity of the rice gel samples was measured to evaluate their physical properties. Results showed that dynamic viscoelastic moduli decreased concomitantly with increasing shearing time and speed, whereas they increased concomitantly with increasing temperature. Analyses of the models revealed that shearing speed was the most dominant factor affecting rice gel preparation in HST, while shearing time and temperature strongly affected the texture. These results are expected to be applicable to the design of HST equipment for rice gel production.
Effects of acid modification on the physicochemical, rheological, microstructural and expansion on cassava starch with lactic, acetic and citric acids in proportions of 5 %, 10 % and 15 % were investigated. This effect was verified on swelling power and solubility index, rheology, pH, scanning electron microscopy, thermal analysis and baking test. The results were available by ANOVA and Tukey test. The study indicates that the acid treatment influenced significantly the physicochemical properties. The lactic and acetic acids did not modify the rheological model of the cassava starch, but showed a reduction in the apparent viscosity. The acetic and lactic acids had a strong influence on the starch granules. Thus, the acid modification of cassava starch promotes the significant changes in starch properties.