摘要：
This study was aimed to characterize and identify a fraction from silver carp muscle hydrolysates (SCMHs) with cryoprotective effects on yeast. The SCMHs were obtained from the hydrolysis of silver carp (Hypophthalmichthys molitrix) muscle with Protamex at 50 degrees C for 15-240 min. The addition of SCMH generated from 30 min of proteolysis (SCMH-30) led to an increase in the yeast survival rate from 0 - 1% (control) to 82-91% after 1-2 freeze-thaw cycles. The SCMH-30 was further separated into two fractions using gel filtration chromatography. The fraction F2 with lower average molecular weight exhibited better cryoprotective effect on yeast, which was further characterized via HPLC-MS/MS. Among a total of 2500 identified peptides, 90% of them had molecular weight between 1000 and 3000 Da, which were mainly derived from parvalbumins. The selected primary peptides were rich in glutamic and aspartic acid residues and exhibited structural and sequential similarities with type IV fish antifreeze proteins, which likely contributed to the high antifreeze activity of F2 from SCMH-30. Results from this study provided an approach for development of effective cryoprotectants using SCMHs and helped to understand the underlying mechanism governing cryoprotective effect of SCMH-30 on yeast.
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).
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：
[杨有望; 任梦影; 易翠平; 俞健] School of Chemistry and Biological Engineering, Changsha University of Science and Technology, Changsha, 410114, China;[周素梅; 佟立涛] Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
会议名称：
2016年粮食食品与营养健康产业发展科技论坛暨行业发展峰会
会议时间：
2016-08-04
会议地点：
呼和浩特
会议论文集名称：
2016年粮食食品与营养健康产业发展科技论坛暨行业发展峰会论文集
关键词：
乳酸菌;酵母;发酵;鲜湿米粉;品质
摘要：
对比研究2株乳酸菌、2株酵母与自然发酵对鲜湿米粉品质的影响。结果表明,Lactobacillus plantarum CSL23发酵36~48 h时,鲜湿米粉的拉伸力、硬度、弹性、内聚性、咀嚼性、回复性和吸水率在4株菌中最高,蒸煮损失率最低。Lactobacillus fermentum CSL30发酵48 h时,鲜湿米粉的拉伸力、弹性、内聚性、回复性、吸水率和蒸煮损失率仅次于L. plantarum CSL23,而硬度、黏性、咀嚼性最低。自然发酵的鲜湿米粉在发酵60 h时,鲜湿米粉的拉伸力、硬度和咀嚼性较好,质构特点和蒸煮性质居中。Saccharomyces cerevisiae CSY13发酵使鲜湿米粉具有明显的风味特征,但黏性较高、内聚性低。Trichosporon asahii CSY07发酵对鲜湿米粉的拉伸力、质构特点和蒸煮性质的影响均不如自然发酵,但对风味的影响仅次于S. cerevisiae CSY13。总之,乳酸菌有利于鲜湿米粉的食用品质,酵母菌有利于风味;纯种发酵均可以使鲜湿米粉的品质在更短时间内达到最佳状态。
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
