关键词：
Change;Cold storage;Degradation;Grass carp;Muscle protein
摘要：
The aim of present study was to evaluate the influence of cold storage on composition and properties of grass carp protein. The results show that muscle proteins of grass carp were degraded and underwent conformational changes when stored at 4 °C, and significant changes of the proteins content, as shown by the SDS-PAGE fingerprint, was observed after 6 days of storage. Protein’s surface hydrophobicity and total SH content increased during the first 4 days and then decreased gradually up to 10 days. The Ca 2+ -ATPase activity of protein decreased gradually during the storage period. The high MW proteins easily degraded during the cold storage, and the proteins with low MW were relatively stable but still gradually degraded. So the key time point for cold storage of grass carp is approximately 4-6 days. Copyright 2019 Zoological Society of Pakistan.
关键词：
By-products of silver carp;Cryoprotection;Freeze-thaw;Protein hydrolysate;Surimi
摘要：
The cryoprotective effects of different amounts of protein hydrolysates prepared from by-products of silver carp using Protamex and Alcalase on surimi that were subjected to six freeze-thaw cycles were investigated. Commercial cryoprotectant (8% w/w 1:1 sucrose-sorbitol blend, SuSo) and control (without cryoprotectant) groups were used for comparison. After six freeze-thaw cycles, the lowest actomyosin extractability, Ca2+-ATPase activity and total sulfhydryl content, along with the highest surface hydrophobicity of actomyosin, were observed in the control group (P < 0.05). On the contrary, the group with addition of 2 g of hydrolysate prepared by Protamex hydrolysis (PH-2) displayed the highest actomyosin extractability, Ca2+-ATPase activity and correspondingly, lowest surface hydrophobicity of actomyosin (P < 0.05). Total sulfhydryl content of actomyosin and textural properties of heat-set surimi gels were similar between samples with PH-2 and those with SuSo (P > 0.05). Differences in molecular weight distribution, total and free amino acid compositions between the hydrolysates prepared by Protamex and Alcalase hydrolysis were possible reasons attributing to their variable cryoprotective effects on freeze-thawed surimi. Results from this study clearly support that hydrolysate prepared by Protamex hydrolysis at an appropriate amount could serve as an effective cryoprotectant without increasing the sweetness of surimi products. Furthermore, our findings suggest that the hydrolysates follow a different cryoprotection mechanism compared to SuSo (sucrose-sorbitol blend).
关键词：
Rice;Semidry-milling;Hot air treatment;Fissures;Qualities
摘要：
To investigate the effects of hot air treatment (HAT) on the quality attributes of Indica rice semidry-milling, HAT was applied at various temperatures (45-120 degrees C) and processing times (0-240 min). The changes in grain-surface cracking, moisture absorption rate, damaged starch, rheological properties, microbial decontamination, and texture qualities were evaluated. HAT induced many cracks in the rice grains, shortening the soaking time to reach maximum water content (28%) to 8 min. However, at high temperatures, extending the HAT time slowed the water absorption rate. Under the optimum HAT conditions and soaking time, the total viable counts in the rice flour were similar to those of dry-milled rice flour (10(2)-10(3) cfu/g), with no conforms and few yeasts and molds. The damaged starch content, rheological and texture properties were similar to those of wet-milling. Therefore, an appropriate HAT can shorten the soaking time of the rice and clean it during the milling process. (C) 2017 Elsevier Ltd. All rights reserved.
通讯机构：
Department of Food & Biological Engineering, Changsha University of Science & Technology, Hunan Provincial Engineering Technology Research Center of Aquatic Food Resources Processing, Changsha, China
作者机构：
[王建辉; 俞健; 刘小芳; 李向红; 刘永乐; 王发祥] College of Chemistry and Biology Engineering, Changsha University of Science and Technology, Hunan Provincial Engineering Research Center for Food Processing of Aquatic Biotic Resources, Changsha, 410114, China
通讯机构：
College of Chemistry and Biology Engineering, Changsha University of Science and Technology, Hunan Provincial Engineering Research Center for Food Processing of Aquatic Biotic Resources, Changsha, China
摘要：
In present study, phase separation of soluble rice protein (SRP) and different polysaccharides were used to create specific structures with various structural and textural properties. The phase behavior and phase separation mechanism of mixtures of SRP and kappa-carrageen/dextran (25 degrees C, pH 7.0 and 0.1 mol/L NaCl) were investigated by means of phase diagram construction, confocal laser scanning microscopy (CLSM) and stress-controlled rheometry. Phase diagrams combined with CLSM indicated that entropic effects of depletion interaction were the main driving force behind the phase separation of soluble rice protein and polysaccharides. Results also demonstrated that electrostatic interaction played an important role in the observed phase separation. CLSM and frequency sweeps revealed the effective association among rice proteins and formation of network-like structures in the mixed systems. These findings suggest that controlled phase separation and gelation of mixed SRP/polysaccharide systems have potential to create rice protein foods with novel textural characteristics. (C) 2015 Elsevier Ltd. All rights reserved.
