Effect of ice and cold storage on the chemical and technological characteristics of Egyptian crab meat

Effect of ice and cold storage at 4°C on the chemical and technological characteristics of one of red local Egyptian crab (Carcinw meanas) has been studied. Such studies involved the determinations of pH values, moisture, total nitrogen, protein nitrogen, ether extract, acid value, thiobarbituric acid value (TBA) and total bacterial count (TC). It has been found that the shelf life of ice stored crabs was 2 days. Raw crabs stored at 4°C can be kept without any deterioration for 8 days. Dipping of raw crab in 20 ppm chlorotetracycline (CTC) for 20 min raised the keeping period at 4°C up to 11 days. Cooked crabs can be stored at 4°C without any spoilage for 14 days. However, dipping of cooked crabs in 20 ppm of CTC for 20 min increased the keeping period to 17 days.     

Effect of freezing, thawing and frozen storage on physico-chemical and sensory characteristics of buffalo meat

A study was conducted on some physico-chemical and sensory characteristics of buffalo meat frozen by plate and blast freezing and stored at −15 ± 3°C for a period of 3 months. A marginal increase in pH values and drip losses were observed during the storage period. Drip losses were less in blast frozen samples. WHC, cooking losses thermal shrinkage and WB Shear values indicated inconsistent results, during storage. Similar observations were recorded with regard to tyrosine and TBA values. No significant differences in the physico-chemical characteristics were observed between meat cuts and minced meat. Plate frozen meat samples scored higher for texture, juiciness and aroma. Both the plate and blast frozen meat samples, however, were similar in overall quality according to taste panel results.     

Cryoprotectants improve physical and chemical properties of frozen blue crab meat (Callinectes sapidus)

The storage stability of cryogenically frozen crab meat treated with cryoprotectants was compared with pasteurised and water-treated frozen samples to determine changes in physical and chemical properties. Commercially processed, hand-picked blue crab meat was treated with solutions of polydextrose, sucrose + sorbitol/sodium tripolyphosphate or water, vacuum packaged, and cryogenically frozen prior to storage at ?29°C. All treatments were compared with an untreated reference control stored at ?65°C and a pasteurised sample stored at 1.1°C. Samples were evaluated for physical and chemical changes at 4-week intervals over 32 weeks of storage. Cryoprotectants improved oxidative stability, drip loss, expressible moisture, texture, and colour compared to untreated reference and pasteurised samples.     

不同冻藏温度对鸡胸肉电阻抗特性的影响

为研究不同冻藏温度条件下鸡胸肉的阻抗特性差异,将白羽鸡鸡胸肉在-10、-20与-30℃的条件下分别冻藏3、6、9、12个月,相应的冻藏时间取20块鸡胸肉解冻,在0.05²00 k Hz的频率范围内,选取6个频率点进行电阻抗特性的分析,检测鸡胸肉的阻抗幅值与阻抗相对变化值（Q值）以及理化品质指标。结果表明:相同冻藏时间内,冻藏温度越高,鸡肉的解冻汁液流失率、脂肪氧化程度、剪切力越大（p<0.05）,蛋白质溶解度越小（p<0.05）。随着检测频率的上升,不同冻藏温度鸡胸肉的阻抗幅值均呈下降趋势。在50 Hz频率时,各个冻藏时间的鸡胸肉在不同冻藏温度条件下的阻抗幅值均存在差异（p<0.05）;在200 k Hz频率时,-10℃处理组的阻抗幅值在冻藏3个月与6个月时显著低于其它处理组（p<0.05）。在冻藏过程中,-10℃冻藏组的Q值均显著高于-30℃处理组的Q值（p<0.05）。冻藏温度对解冻鸡胸肉的阻抗幅值与Q值产生影响,阻抗特性的差异能够反映冷冻鸡胸肉品质的差异,不同冻藏温度鸡肉的电阻抗特性差异为阻抗技术在冻肉品质检测中的应用提供了基础。      

冻藏时间对不同种类原料肉理化特性的影响

以猪肉、鸡肉为研究对象,在-18℃冻藏不同时间(0,1,2,4,8周)后,对原料肉色泽、系水力(失水率和系水率)、蒸煮损失率、pH值、氨基酸以及游离脂肪酸组成进行测定.结果表明:随着冻藏时间增加,原料肉失水率与蒸煮损失率显著升高(P<0.05);系水率显著下降(P<0.05).随贮藏时间延长,原料肉中赖氨酸、丙氨酸和半...     

Effect of storage on the rheological and parotta-making characteristics of frozen parotta dough

The effect of storage of frozen parotta dough (FPD) and ready-to-bake frozen parotta dough (R-FPD) at -20 °C for 3 months on the rheological and baking characteristics, respectively, were studied. The optimum thawing conditions for FPD and R-FPD were found to be 1 min in the microwave oven or 16 h in the refrigerator. The rheological characteristics of FPD showed a decrease in farinograph peak consistency from 240 to 200 BU and an increase in extensograph extensibility from 155 mm to 170 mm due to storage. The major protein fractions of FPD as indicated by the electrophoretic patterns remained unchanged up to a period of 3 months. However, when compared to FPD the protein bands in the high-molecular-weight region of glutenin were less intense for baked parotta from R-FPD. The overall rating of parotta was good even after 3 months of storage as indicated by the sensory evaluation of parottas from R-FPD samples.     

Effect of refrigerated and frozen storage on the survival of Campylobacter jejuni in cooked chicken meat breast

This experimental work aimed to examine the survivability of Campylobacter jejuni in cooked chicken breast under several conditions: storage for 1, 3, and 7 d at refrigerated temperatures (4 °C) and for 20 d at frozen temperatures (-18 °C). In addition, storage at ambient temperature (26 to 28 °C) was involved. Chicken samples were inoculated with a mixed culture of C. jejuni strains (ATCC: 29428 and 33219) of known concentrations (50 and 500 CFU/g). Bacterial cells were recovered and enumerated using standard procedure (Preston method). Bacteria were not detected in the majority of samples stored at ambient temperature. Refrigeration reduced survivals in 95, 90, and 77.5% for samples inoculated with 500 CFU/g and kept for 1, 3, and 7 d, respectively. The maximum reduction reached 1 log(10) cycle for all refrigeration durations. It was observed that bacteria died in 17.5% of samples kept for 7 d at 4 °C. However, survivors in samples inoculated with 50 CFU/g were not detected in 50, 65, and 55% of samples kept for 1, 3, and 7 d, respectively. Freezing rendered survivors not detectable in 70% of samples inoculated with 50 CFU/g, while survived viable counts were reduced in 92.5% of samples inoculated with 500 CFU/g. These findings suggested that C. jejuni could be killed or just sublethally injured with or without reduction in viable counts under the investigated storage temperatures, which may indicate the ability of this bacterium to survive in chicken meat stored under refrigerated and frozen conditions.     

Effect of gamma irradiation and frozen storage on chemical and sensory characteristics of rainbow trout (Oncorhynchus mykiss) fillet

The present study was conducted to evaluate the combined effect of low‐dose gamma irradiation (1, 3 and 5 kGy) and frozen storage (5 months at ?20 °C) on chemical and sensory characteristics of rainbow trout (Oncorhynchus mykiss) fillet. Our statistical analysis showed that irradiation process and frozen storage time had a significant effect (P < 0.05) on total volatile nitrogen (TVN), peroxide value (PV), thiobarbituric acid (TBA) and pH. The level of all of these factors increased with increasing frozen storage time. At the end of the fifth month of frozen storage, the lowest and the highest level of TVN, PV and TBA were corresponding to the irradiated samples at 3 and 5 kGy, respectively. In terms of the overall acceptability of their texture, odour, colour and taste, irradiated samples at 3 kGy had the best quality and remained acceptable after 5 months frozen storage. The optimum dose of gamma radiation of rainbow trout fillets according to chemical and sensory analysis was obtained at 3 kGy.     

Biochemical and technological characteristics of hot chicken meat

In the hot breast and leg muscles of broiler chicken the level of ATP, the 'R' value, the lactic acid content, the pH value, the length of sarcomers, the water and fat retention capacity, the fat emulsion stability, thermal drip, and the extractability of protein fraction were investigated. It was found that in the breast muscles the onset of rigor mortis commenced within 30–60 min, and in the leg muscles as early as 15–30 min after killing of the birds. The deepest rigor mortis occurred between the first and fourth hour, and then gradually declined, sooner in the leg than in the breast muscles. The addition of sodium chloride (2.0–2.5%) to the minced pre-rigor meat not later than 40 min after slaughter, or better, an injection of NaCl brine into intact muscles 15 min after slaughter of birds, preserved their good technological properties.
The tenderness and the thermal drip of hot salted and chilled salted muscles showed no significant differences, but water retention and fat emulsifying capacity were better in the hot salted meat samples. The hot salted and cooked muscles were preferred by the sensory panel to corresponding samples of chilled muscles.
From the hot salted chicken meat more sarcoplasmic and myofibrillar proteins were extracted than from meat salted after chilling. However, after frozen storage the extractability of myofibrillar proteins were higher in the salted chilled meat.     

Effect of modified atmosphere packaging,storage period,and storage temperature on the residual nitrate of sliced-pastırma,dry meat product,produced from fresh meat and frozen/thawed meat

The amount of nitrite in sliced-pastirma made, from fresh or frozen (which was stored at −18 °C for 240 days and then thawed at 10 °C for 24 h) M. Longissimus dorsi muscle was determined. Sliced-pastirma samples were stored in modified atmosphere packages (50% N₂ + 50% CO₂) at 4 and 10 °C for 150 days, and the amount of residual nitrite was measured after 0, 30, 60, 90, and 150 days of storage. The residual nitrite of pastirma samples made with frozen/thawed meat was higher than that of the pastirma made from fresh meat at both 0 day and at the end of the storage (150 days). The storage temperature (p < 0.01), storage period (p < 0.01) and the storage period × the storage temperature interaction (p < 0.01) had significant effects on the amount of the residual nitrite.     

复热方式对冻熟河蟹品质的影响

为了解加热对河蟹酶解液（River crab enzymolysis liquid,RCEL）蟹味变化的影响,本试验以河蟹高压浸提液（High pressure extract of low valueriver crab,HPEC）为底物,利用风味蛋白酶进行酶解得到RCEL,将RCEL经真空浓缩后,收集酶解液的浓缩液（Concentration of the enzymatic solution,CES）和蒸发的水（Evaporated water,EW）,分别设置不同的真空浓缩温度（20、30、40、50、60、70 ℃）和浓缩体积（浓缩至原体积的3/4、1/2、1/4）。将收集到的9个CES和9个EW样品分别进行电子鼻PCA分析。采用顶空-固相微萃取和气相色谱-质谱联用技术（HS-SPME-GC-MS）分析HPEC、RCEL和真空浓缩温度为50 ℃时的50CES和50EW样品的挥发性风味物质变化。电子鼻分析结果表明,河蟹酶解液只要经过真空浓缩处理,无论温度和体积如何变化,CES与RCEL之间的距离都相对较远,即两者整体气味差异越大。相比较而言,真空浓缩温度比浓缩体积的变化对蟹味的影响更大。GC-MS分析结果表明,4组样品中的挥发性风味物质的相对质量浓度大小关系为RCEL>50CES>HPEC>50EW,其值分别为13.9753、8.3862、6.2235、1.0855 μg/L,真空浓缩后50CES样品的风味物质明显减少。GC-MS分析表明,形成蟹味的风味物质可能是由醛类（苯甲醛、大茴香醛、3-乙基苯甲醛和2,4,5-三甲基苯甲醛）、酯类（N-苯甲酰基甘氨酸甲酯）、酮类（丁酰基丙酮和苯亚甲基苯乙酮）、烃类（2,2-二甲基十四烷、十一烷、9-辛基-二十烷和正二十烷）、醚类（4-烯丙基苯甲醚）和杂环类（2,5-二甲基吡嗪）等构成的。     

辣椒籽油对肉糜低温贮藏特性的影响

为探讨辣椒籽油对猪肉肉糜的保鲜效果,研究了辣椒籽油添加及不同包装方式对猪肉肉糜在4℃低温贮藏条件下的质构、色差、保水性、挥发性盐基氮、TBARS值、菌落总数等指标的影响。结果表明:辣椒籽油的添加使肉糜的红度值提高了2倍,且对肉糜的pH、硬度都有积极影响,辣椒籽油与真空包装结合使用使肉糜的脂肪氧化、蛋白氧化变缓。贮藏第9天对照组TBARS值已达到1.95mg/kg,辣椒籽油组仅1.39mg/kg;对照组TVB-N值达到28.7 mg/100g,辣椒籽油组仅16.8mg/100g。在辣椒籽油和真空包装的联合作用下可有效延长肉糜保质期2d以上。     

Effect of full-fat soy paste and textured soy granules on quality and shelf-life of goat meat nuggets in frozen storage

Goat meat nuggets were prepared using commercially available textured soy granules and reduced beany flavour full-fat soy paste (FFSP) made by simple processing technology to compare the performance of these proteins in a comminuted meat system. Addition of soy proteins (soy paste and soy granules) did not significantly affect the product yield, pH, moisture and fat percentage whereas protein content and water holding capacity (% expressible water) were significantly (p>0.05) lower in nuggets with 15% soy paste. Lower force was required to compress or shear the sample as hardness, springiness, gumminess and chewiness decreased in soy paste incorporated nuggets. Soy proteins either paste or granules, did not affect sensory attributes except flavour and overall acceptability. Nuggets with soy paste and control ones did not differ significantly for flavour and overall acceptability whereas nuggets with soy granules were rated significantly (p>0.05) lower. The nuggets remained stable with minor changes in physico-chemical, microbiological and sensory quality during frozen storage (-18±1°C) for 90days. It is concluded from this study that FFSP could be successfully incorporated in comminuted meat systems for producing quality products similar to commercially available soy granules.     

包装方式对冷藏过程中牦牛肉蛋白质生化特性的影响

为研究不同包装方式对冷藏过程中牦牛肉蛋白质生化特性的影响。取牦牛背最长肌,采用真空和非真空2种包装方式,在0~4℃下分别冷藏0、2、4、6、8、10、12 d,分析其在冷藏过程中蛋白质生化特性变化。结果显示,随着冷藏时间的延长,真空和非真空包装的牦牛肉肌原纤维蛋白和肌浆蛋白均表现出不同程度的降解,但2种包装方式间差异不显著。真空组和非真空组肌原纤维蛋白小片化指数和表面疏水性均呈显著(P0.05)上升趋势,肌动球蛋白盐溶性、巯基含量、Ca~(2+)-ATPase酶活性则均呈显著(P0.05)下降趋势。2种包装方式下的肌动球蛋白盐溶性、Ca~(2+)-ATPase酶活性和肌原纤维蛋白表面疏水性、肌原纤维蛋白小片化指数在0~8 d存在显著(P0.05)差异,10 d以后差异不显著。研究表明,牦牛肉在冷藏期间蛋白质发生了显著降解和变性,含氧包装促进了肌原纤维蛋白小片化和表面疏水性的增加,加重了肌动球蛋白盐溶性、巯基含量、Ca~(2+)-ATPase酶活性的降低。     

Observations on some chemical and physical characteristics of buffalo meat

Proximate composition, sarcoplasmic and myofibrillar protein fractions of buffalo meat were similar to those of beef. Buffalo meat was also rich in lysine. Meat from young animals had a lower collagen content than that from old ones. As the temperature of holding the carcasses was increased, the rate of pH fall was faster. Meat from stressed animals showed a higher ultimate pH. Percentage of cooking loss and thermal shrinkage was higher in muscles of old animals than in young ones, which probably reflected the poor condition of the older animals. Meat cooked by pressure cooking showed lower Warner-Bratzler shear values as compared with meat cooked in boiling water.     

Effect of high voltage electrostatic field treatment on thawing characteristics and post-thawing quality of frozen pork tenderloin meat

The thawing characteristics and post-thawing quality of frozen pork treated with high voltage electrostatic fields (HVEF) were compared with those of an air-thawed control. A multiple points-to-plate electrode operating at voltages above 6 kV significantly shortened the thawing time. Under electrode voltages 4, 6, 8, and 10 kV, thawing times were 70, 52, 46, and 40 min respectively, versus 64 min in the control. HVEF treatment was particularly effective in the temperature range −5–0 °C. HVEF treatment reduced the total microbial counts in thawed frozen meat by 0.5–1 log CFU/g, without affecting meat quality. During five days of post-thawing storage, the volatile basic nitrogen (VBN) levels increased from 10.64 to 16.38 mg/100 g under 10 kV applied voltage, while the control VBNs increased from 10.66 to 19.87 mg/100 g. This suggests an application potential for HVEF treatment in the thawing and storage of frozen meat.     

A study of the effects of frozen storage on certain functional properties of meat and fish protein

This paper presents a study of the effects of frozen storage on certain functional properties, namely protein solubility, emulsifying capacity, and viscosity, both in meat and in fish.
Correlations between these three functional properties were examined in an attempt to find the easiest and most sensitive method of analysis.
High correlation among the different functional properties tested was found only in the case of fish. This, together with the significant variations in the viscosity values found during the storage period, suggests that the analysis of apparent viscosity is a valuable indicator method for determining alterations occurring in the functional characteristics of fish protein.