Comparative studies of quality changes in white and dark muscles from common carp (Cyprinus carpio) during refrigerated (4 °C) storage

Differences between white and dark muscles from common carp (Cyprinus carpio) in sensory assessment, total viable counts (TVC), total volatile basic nitrogen (TVB‐N), pH, electrical conductivity (EC), biogenic amines (BAs), nucleotide degradation products and colours were investigated under air and vacuum conditions during refrigerated (4 °C) storage. Compared with white muscle, dark muscle had a higher lipid content, but lower crude protein and moisture content. TVC, TVB‐N, pH, and L* value were higher in white muscle, while K value and a* value were higher in dark muscle. Under both conditions, white and dark muscles had significant (P < 0.05) differences in tyramine and cadaverine content. Although dark muscle was significantly (P < 0.05) lower in ATP content, it had higher rate of IMP degradation and K value increase. Taking sensory and microbial indexes into consideration, dark muscle appeared to have a longer shelf life than white muscle under both conditions.     

多糖对鲢鱼皮胶原蛋白膜性能的影响

以鲢鱼皮胶原蛋白和不同多糖为原料制备胶原蛋白-多糖共混膜,通过测定膜的抗拉强度、断裂伸长率、水蒸气透过率、透光率、水溶性等指标,研究多糖对胶原蛋白膜性能的影响。结果表明,壳聚糖/胶原蛋白共混膜的综合性能最佳,当胶原蛋白和壳聚糖的比例为3∶1时,共混膜的力学性能最佳,此时膜的抗拉强度为35.47MPa、断裂伸长率为25.87%,水蒸气透过率、透光率、水溶性较单一胶原蛋白膜有明显的改善。红外光谱、X射线衍射和扫描电镜对其结构进行表征表明,共混膜中胶原蛋白和壳聚糖具有良好的相容性,两者之间存在相互作用。      

Effect of lightly salt and sucrose on rigor mortis changes in silver carp (Hypophthalmichthys molitrix) stored at 4°C

To evaluate the effect of salt and sucrose on rigor mortis changes in silver carp during 72 h at 4 °C, physical (texture parameters, water holding capacity (WHC), cooking loss, L* value) and chemical adenosine triphosphate (ATP‐related compounds, K value, pH value) characteristics were studied. Silver carp were subjected to following treatments: left untreated (CK), treated with 1.8% salt (S) and 1.8% salt incorporating 1.8% sucrose (S+S). Curing treatments predominantly increased IMP content, WHC and texture parameters, retarded cooking loss and discoloration compared with untreated samples. The highest IMP concentration measured in S and S+S all occurred at 4 h, which was prior to that of CK (48 h). K value of S+S did not follow a linear relationship with time. The results indicated that the best eating times of CK, S and S+S were 2, 4 and 4 h at 4 °C, respectively, and curing treatments improved the quality of silver carp during postmortem process.     

Effect of gamma irradiation on the keeping quality and nutrients of tilapia (Oreochromis mossambicus) and silver carp (Hypophthalmichthys molitrix) stored at 1.C

Fillets (skin on) obtained from freshly killed tilapia (Oreochromis mossambicus Peters) and silver carp (Hypophthalmichythys molitrix Curier & Valenciennes) were gamma irradiated at 1.0 kGy at 2–4.C. The chemical con position and thiamin and riboflavin contents of irradiated fish fillets were analysed and compared with those of the non-irradiated fish. Loss of thiamin content of silver carp fillets was significant whereas the thiamin content of tilapia and other constituents of tilapia and silver carp were unaffected. Irradiation at 1.0 kGy markedly reduced the bacterial level of tilapia and silver carp. No significant increase in total counts in both irradiated and non-irradiated samples was found during 5 days' storage at 1.C. The pattern of nucleotide changes in tilapia and silver carp was different. Irradiation had little effect on the concentrations of nucleotide catabolites in both species. Sensory evaluation of flesh colour and flavour was conducted after 5 days' refrigerated storage. Except that the colour of irradiated carp was more reddish, there were no significant differences in other qualities.     

Effect of different precooking methods on chemical composition and lipid damage of silver carp (Hypophthalmichthys molitrix) muscle

The influence of three precooking methods (steaming, oven‐baking and microwave‐cooking) on the chemical composition and lipid quality of silver carp fillets was evaluated. The changes in protein, fat and moisture were found to be significant for all the treatments (P ≤ 0.05). The iron content in the samples subjected to steam‐cooking increased; however, the other precooking methods did not change the mineral contents (P ≥ 0.05). The free fatty acid content of the fillets did not change by the different precooking methods, while thiobarbituric acid (TBA) values increased for oven‐ and microwave‐cooked fillets and remained constant in the steam‐cooked samples. Conjugated diene and browning colour formation levels significantly increased in the oven‐baked fillets. Oven‐baking and microwave‐cooking marginally affected the fatty acid composition of the silver carp. On comparing the raw and precooked fillets, steam‐cooking was found to be the best precooking method on retaining nutritional constituents.     

冻藏对鲢鱼、鲤鱼鱼肉质构影响的比较研究

比较冻藏处理对鲢鱼、鲤鱼鱼肉质质构的影响.采用质构仪对冻藏的鲢鱼、鲤鱼鱼肉进行测定,并与未经冻结的鱼肉指标值进行比较.结果表明,经过冻结的鲤鱼、鲢鱼的硬度、弹性、黏附性、咀嚼性、恢复性等指标值均有所下降,下降幅度不同,与鲤鱼相比较,鲢鱼质构变化明显.     

Effect of frozen storage on thermal stability of sarcoplasmic protein and myofibrillar protein from common carp (Cyprinus carpio) muscle

Thermal stability of sarcoplasmic protein and myofibrillar protein extracted from fresh and frozen common carp was comparatively studied. Total sulphydryl content (SH) in sarcoplasmic protein solution from 5‐month frozen carp decreased by 19.43% compared with fresh sample. The SDS‐PAGE patterns showed that all the bands of sarcoplasmic protein from frozen‐stored samples were almost invisible at 80 °C. Myofibrillar protein from fresh sample exhibited lower turbidity and surface hydrophobicity and higher Ca²⁺‐ATPase activity and SH content than frozen‐stored sample when heated from 20 to 80 °C. The Ca²⁺‐ATPase activity from fresh (M0), 2 (M2)‐ and 5 (M5)‐month frozen‐stored carp was completely lost at 48, 46 and 46 °C, respectively. When heated to 80 °C, the SH content of myofibrillar solutions in M0, M2 and M5 decreased by 26%, 60% and 70%, respectively. Sarcoplasmic and myofibrillar proteins from frozen carp were more susceptible to aggregate during heating treatment.     

茶多酚-海藻糖脱腥液对白鲢鱼贮藏品质的影响

研究比较了茶多酚、海藻糖以及茶多酚-海藻糖脱腥液对白鲢鱼肉的脱腥效果,并选用脱腥效果最好的茶多酚-海藻糖复合脱腥液应用于白鲢鱼肉的冷藏保鲜。通过感官评价、微生物和理化指标分析,研究复合脱腥液处理对白鲢鱼块在0℃贮藏过程中品质变化及货架期的影响。实验结果表明,经脱腥液处理能有效抑制白鲢鱼块冷藏过程中的细菌生长,减缓鱼肉TVB-N值、TBA值和p H的升高,延缓鱼肉感官评分、硬度和咀嚼度的下降,能够延长白鲢鱼块的货架期6 d左右。      

Effects of different filling media on the oxidation and lipid quality of canned silver carp (Hypophthalmichthys molitrix)

The influence of four different filling media (sunflower oil, soybean oil, olive oil and brine) on the oxidation and lipid quality of canned silver carp was evaluated. Hydrolytic rancidity showed that free fatty acid contents in brine and soybean oil canned muscle were higher than olive oil or sunflower oil canned samples. Conjugated diene (CD) levels in soybean oil canned samples increased but the highest CD values were found in canned silver carp using brine as filling medium. Except for olive oil canned muscle, significant increase in thiobarbituric acid (TBA) values was obtained. The highest TBA value was observed in soybean oil canned sample. Canning led to exchange of fatty acids between the fat in the silver carp muscle and the filling media used. Results indicate that the fat composition of canned silver carp tends to be similar to that of the fat used as filling media.     

Quality changes and storage life of common carp (Cyprinus carpio) at various storage temperatures

The shelf life and freshness changes in pond-grown common carp (Cyprinus carpio L) during storage at 0–2°C, 5–6°C and room temperature (26–29°C) were investigated by sensory, microbiological, physical and chemical analyses. The effect of gutting on the shelf life during storage at 0–2°C was examined. Iodine/starch and potassium sorbate were examined for their effects on shelf life of whole fish stored at 0–2°C and 5–6°C. Sensory results indicated that the whole fish had a maximum shelf life of 24 to 25 days at 0– 2°C. The life of the fish to the point beyond which it would be unsuitable for sale (commercial shelf life) was 17 days at 0–2°C. Storage at 5–6°C shortened shelf life 2- to 2.5-fold. At room temperature (26–29°C), spoilage was evident after 13 h. Gutting the carp shortened its storage potential at 0–2°C. Iodine treatment of this species stored at 0–2°C and at 5–6°C did not extend shelf life. The maximum shelf life of sorbate-treated fish at 0–2°C and 5–6°C was extended by 1–2 days, commercial shelf life by 3–4 days. Total volatile basic nitrogen, pH and penetrometer analyses were not reliable indicators of changes in freshness during shelf life. Thiobarbituric acid values were not useful as rancid odours or flavours were not detected during storage.     

Effect of substrate ratios and temperatures on development of Maillard reaction and antioxidant activity of silver carp (Hypophthalmichthys molitrix) protein hydrolysate–glucose system

The study of antioxidant activity of the hydrolysates is necessary during its processing in which Maillard reaction would often occur. To understand the effect of Maillard reaction on antioxidant activity of silver carp protein hydrolysates (SPH), the Maillard reaction products (MRPs) were prepared at different ratios between SPH and glucose by Maillard reaction in powdered state, respectively. MRPs possessed a strong 2, 2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activity and reducing power (P < 0.05). The hydrolysate and glucose heated with the ratio of 2:1 at 60 °C showed high browning intensity and good antioxidant properties (P < 0.05). According to the correlation coefficients of variables included in the hydrolysate–glucose system, good correlations were observed among the antioxidant activities, the absorbance at 294 nm and the loss of free amino groups. The results suggested that Maillard reaction has a good potential to improve the antioxidant activity of SPH.     

K型与I型卡拉胶对白鲢鱼糜持水性及质构冻藏稳定性的影响

目的:以常见的白鲢鱼糜为原料,研究I型和K型卡拉胶对鱼糜质构和持水性差异,以及在反复冻融循环中的影响。方法:对分别加入I、K两种胶体的鱼糜反复冻融后持水性和TPA指标进行显著性分析。结果:未冻融时,I型卡拉胶对降低鱼糜硬度、胶着性、咀嚼性,增加恢复性作用比K型更强(p <0.05);对照组、I型卡拉胶组和K型持水性基本相同(p> 0.05)。反复冻融试验结果表明,添加I卡拉胶对鱼糜硬度、黏性、黏附性、咀嚼性和弹性的保护作用强于添加K卡拉胶,但会降低鱼糜的弹性和持水能力。结论:I型K型卡拉胶鱼糜对TPA影响有差异,I型卡拉胶鱼糜的反复冻融TPA与持水性稳定性更好。     

多糖对鲢鱼皮胶原蛋白膜性能的影响

以鲢鱼皮胶原蛋白和不同多糖为原料制备胶原蛋白-多糖共混膜,通过测定膜的抗拉强度、断裂伸长率、水蒸气透过率、透光率、水溶性等指标,研究多糖对胶原蛋白膜性能的影响.结果表明,壳聚糖/胶原蛋白共混膜的综合性能最佳,当胶原蛋白和壳聚糖的比例为3:1时,共混膜的力学性能最佳,此时膜的抗拉强度为35.47MPa、断裂伸长率为25.87％,水蒸气透过率、透光率、水溶性较单一胶原蛋白膜有明显的改善.红外光谱、X射线衍射和扫描电镜对其结构进行表征表明,共混膜中胶原蛋白和壳聚糖具有良好的相容性,两者之间存在相互作用.     

Effects of chitosan coating on quality and shelf life of silver carp during frozen storage

The effects of chitosan coating on quality and shelf life of silver carp during frozen storage were investigated. Fish samples were treated with aqueous solution of 2% chitosan, and then stored at −3 °C for 30 days. The control and the treated fish samples were analyzed periodically for microbiological (total viable count), chemical (pH, TBA, TVB-N, K-value), and sensory characteristics. The results indicated that the effect of chitosan coating on fish samples was to retain their good quality characteristics and extend the shelf life during frozen storage, which was supported by the results of microbiological, chemical, and sensory evaluation analyses.