Use of Electrolyzed Oxidizing Water for Quality Improvement of Frozen Shrimp

The bactericidal effect of electrolyzed oxidizing (EO) water was evaluated on Escherichia coli O157:H7‐inoculated and Salmonella‐inoculated shrimp. The shrimp were inoculated on day 0 and stored frozen at ‐20°C. Bacterial enumeration was done on days 0, 24, 49, and 119 of frozen storage. Acidic EO water at 40 ppm free available chlorine was as effective as aqueous chlorine of the same concentration and was significantly more effective (P < 0.05) than tap water in reducing pathogen load on the inoculated shrimp. Further reduction of pathogen numbers was observed after each frozen storage period. Prewashing with alkaline EO water did not enhance the bactericidal activity of the acidic EO water on the shrimp. The washed acidic EO water of the inoculated shrimp had a nondetectable bacterial population compared with treated aqueous chlorine, alkaline EO water, and tap water. Non‐inoculated shrimp subjected to similar treatments were served cooked or uncooked to a minimum of 10 experienced panelists for sensory evaluation on days 0, 24, 49, and 119 of frozen storage. The cooked shrimp were evaluated for the presence of off‐odor, juiciness, tenderness, shrimpy flavor, aftertaste, and overall acceptability; whereas the raw shrimp were evaluated for color, firmness, presence of off‐odors, melanosis, and overall acceptability. Raw shrimp thawed from each frozen storage period were stored at refrigeration temperature (4 °C) for 3 d to observe for melanosis. No difference of sensory attributes was detected among the various treatment groups. Therefore, acidic EO water can be used as an effective disinfectant to replace aqueous chlorine for thawing shrimp blocks.     

熟制麻辣小龙虾冷藏和冻藏条件下的品质变化

研究熟制麻辣小龙虾在冷藏和冻藏条件下的品质变化,将小龙虾油炸后拌料入味,真空包装并进行沸水 煮制杀菌（沸水煮制20 min后快速冷却）,分别在4 ℃和－18 ℃条件下贮藏,通过感官评分、菌落总数、大肠杆 菌数量、总挥发性盐基氮（total volatile base nitrogen,TVB-N）值、pH值及食盐含量测定对麻辣小龙虾的品质变 化进行研究。结果表明：从感官评定结果、菌落总数和TVB-N值综合评判,4 ℃冷藏和－18 ℃冻藏的麻辣小龙虾 能够保持最佳品质的贮藏时间分别为4 周和4 个月;在保质期内,麻辣小龙虾的菌落总数＜4.7 （lg（CFU/g））, TVB-N值＜30 mg/100 g,pH值在弱碱性范围内变化;4 ℃冷藏小龙虾贮藏前3 周的食盐含量呈逐渐升高趋势（达 1.99%）,贮藏3 周后变化不显著（P＞0.05）,而－18 ℃冻藏小龙虾的食盐含量变化缓慢,保持在1.6%～1.8%范 围内。经感官评定,保质期内的麻辣小龙虾风味鲜美、品质优良。     

杨梅多酚对生食金枪鱼冷藏过程中品质的影响

研究杨梅多酚(bayberry polyphenols,BP)作为天然护色剂和保鲜剂对生食金枪鱼冷藏过程中品质的保护作用。使用纯水(对照组)、0.3 g/100 mL杨梅多酚(BP-0.3处理组)、0.7 g/100 mL杨梅多酚(BP-0.7处理组)和0.9 g/100 mL杨梅多酚(BP-0.9处理组)溶液浸泡金枪鱼肉,测定(4±0.5)℃冷藏过程中鲜度、色泽和脂质氧化指标的变化。结果表明,在金枪鱼肉冷藏过程中,杨梅多酚可以显著抑制挥发性盐基氮值、K值、菌落总数、高铁肌红蛋白含量和硫代巴比妥酸值的升高(P0.05),能显著延缓肌红蛋白损失、色泽衰败和感官品质降低(P0.05)。4℃冷藏条件下对照组金枪鱼肉的生食货架期为3 d,BP-0.3处理组的生食货架期为5 d,BP-0.7和BP-0.9处理组的生食货架期可延长至6~7 d。BP-0.9处理组对金枪鱼肉的品质保护作用和BP-0.7处理组无显著差异(P0.05)。经综合评价,0.3~0.7 g/100 mL杨梅多酚溶液可作为一种有效的天然护色剂和保鲜剂应用于冷藏生食金枪鱼。     

超声联合微酸性电解水处理对真空包装海鲈鱼冷藏期间品质变化的影响

为研究超声与微酸性电解水联合处理对真空包装海鲈鱼冷藏期间品质变化的影响,将新鲜鲈鱼片分别使用20?kHz 600?W超声(ultrasonic,US)、微酸性电解水(slightly acidic electrolytic water,SAEW)、超声联合微酸性电解水(US+SAEW)处理10?min,以无菌水浸渍处理...     

酸性电解水对成品豆腐的杀菌效果及品质影响研究

本实验将酸性电解水作为成品豆腐的杀菌液,研究酸性电解水对成品豆腐的杀菌效果以及品质的影响。结果表明:酸性电解水浸泡豆腐,有利于减少豆腐的微生物。20min的浸泡时间可以使豆腐的细菌总数从3.64logCFU/g降低到2.34logCFU/g。另外,仪器测定结果表明酸性电解水浸泡对豆腐的硬度影响很小、对色泽稍有影响;感官评价结果表明酸性电解水浸泡基本不影响豆腐的感官品质。     

不同形态南美白对虾贮藏特性研究

以养殖南美白对虾为研究对象,分别经去头/去壳处理,对整虾、去头虾和虾仁在(0±0.5)℃贮藏过程中感官评分、气味组成、pH、挥发性盐基氮(TVB-N)、酚氧化酶(PO)活力和细菌总数(APC)的变化情况进行分析。结果表明,不同形态对虾在贮藏过程中的腐败特征明显不同,表现在,感官评分都呈下降趋势,但下降幅度和造成评分下降的原因有所差异;PO活力变化有明显差异,整虾PO活力相对较高,而虾仁基本无PO活力;不同形态对虾在货架期终点时的气味组成也有所不同;TVB-N和APC都呈上升的趋势,在指示货架期终点时表现出较好的一致性,而感官评分相对滞后。综合感官、生化和微生物指标,整虾、去头虾和虾仁在(0±0.5)℃条件下的货架期分别为7、9和11 d。     

罗非鱼片在冷藏过程中的品质变化研究

综合研究冷藏过程中罗非鱼片品质变化的相关几项指标,包括感官值、pH 值、挥发性盐基氮(TVB-N)值、K 值、Ca2+-ATP 酶活性值、脂肪氧化(TBA)值。结果表明：TVB-N 值、K 值、Ca2+-ATP 酶活性值和感官值有很好的相关性,表现为：罗非鱼片品质开始变差出现在第5 天左右,鱼片感官值下降到16,K 值增加到29.5%,TVB-N 值增加到15.775mg/100g,Ca2+-ATP 酶活性降低了27.24%;鱼片品质开始恶化出现在第12 天左右,感官值下降到8,TVB-N 值为29.96mg/100g,K 值为54%,Ca2+-ATP 酶活性降低了53.36%。通过综合分析这些指标可评价冷藏过程中罗非鱼片的品质变化。     

Pathogen Reduction and Quality of Lettuce Treated with Electrolyzed Oxidizing and Acidified Chlorinated Water

ABSTRACT: The efficacy of electrolyzed oxidizing (EO) and acidified chlorinated water (45 ppm residual chlorine) was evaluated in killing Escherichia coli O157:H7 and Listeria monocytogenes on lettuce. After surface inoculation, each leaf was immersed in 1.5 L of EO or acidified chlorinated water for 1 or 3 min at 22 °C. Compared to a water wash only, the EO water washes significantly decreased mean populations of E. coli O157:H7 and L. monocytogenes by 2.41 and 2.65 log10 CFU per lettuce leaf for 3 min treatments, respectively (p < 0.05). However, the difference between the bactericidal activity of EO and acidified chlorinated waters was not significant (p > 0.05). Change in the quality of lettuce subjected to the different wash treatments was not significant at the end of 2 wk of storage.     

冷却猪肉贮存中的品质变化及货架期预测

本文研究了不同贮藏温度下冷却猪肉的品质变化,运用因子分析法,结合Q10模型,建立货架期预测模型。在0、5、10、15、20 ℃贮藏环境中,以感官品质、菌落总数、TVB-N、TBARS、pH值、色值(L*、a*、b*)为品质评价指标,找出反应多种理化指标的主成分因子。且进行理化因子与感官品质皮尔逊积聚相关性分析,通过感官品质货架终点获得理化因子的限值,建立冷却猪肉货架期预测模型。研究结果表明：在不同贮藏温度下冷却猪肉的菌落总数、TVB-N值、pH值、TBA、色值（b*）呈上升趋势值随着贮藏时间的延长而增加;其感官品质、色值（a*）随着贮藏时间的延长而呈下降趋势;且贮藏温度越高各项指标变化越快。在4、12℃贮藏条件下对冷却猪肉品质预测模型进行验证,相对误差均在±10%之内。验证试验表明,所建模型适用于冷却猪肉货架期预测。     

微酸性电解水冰对罗非鱼片的保鲜效果

为探讨微酸性电解水冰对罗非鱼片保鲜效果的影响,对比分析微酸性电解水冰与自来水冰贮藏罗非鱼片的感官评分、pH值、总挥发性盐基氮含量、K值和菌落总数的变化。结果表明：与自来水冰处理组相比,微酸性电解水冰能抑制1 ℃贮藏过程中罗非鱼片的总挥发性盐基氮含量、K值、菌落总数的增加;微酸性电解水冰处理的罗非鱼片感官评分更高;综合来看,微酸性电解水冰处理可以将罗非鱼片的货架期延长3～4 d,能更有效地保持罗非鱼片的品质。本研究可为微酸性电解水冰应用于水产品流通环节的保鲜提供理论参考。     

Effects of Frozen Storage on Survival of Staphylococcus aureus and Enterotoxin Production in Precooked Tuna Meat

This study investigated the survival of Staphylococcus aureus in precooked tuna meat for producing canned products during frozen storage (?20 ± 2 °C) as well as its growth and enterotoxin production at 35 to 37 °C after the storage. Samples (50 ± 5 g) of precooked albacore (loin, chunk, and flake) and skipjack (chunk and flake) tuna were inoculated with 5 enterotoxin‐producing strains of S. aureus at a level of approximately 3.5 log CFU/g and individually packed in a vacuum bag after 3 h incubation at 35 to 37 °C. Vacuum‐packed samples were stored in a freezer (?20 ± 2 °C) for 4 wk. The frozen samples were then thawed in 37 °C circulating water for 2 h and incubated at 35 to 37 °C for 22 h. Populations of S. aureus in all precooked tuna samples decreased slightly (<0.7 log CFU/g) after 4 wk of storage at ?20 ± 2 °C, but increased rapidly once the samples were thawed and held at 35 to 37 °C. Total S. aureus counts in albacore and skipjack samples increased by greater than 3 log CFU/g after 6 and 8 h of exposure to 35 to 37 °C, respectively. All samples became spoiled after 10 h of exposure to 35 to 37 °C, while no enterotoxin was detected in any samples. However, enterotoxins were detected in albacore loin and other samples after 12 and 24 h of incubation at 35 to 37 °C, respectively. Frozen precooked tuna meat should be used for producing canned tuna within 6 to 8 h of thawing to avoid product spoilage and potential enterotoxin production by S. aureus in contaminated precooked tuna meat.     

黑鳍生食金枪鱼解冻后不同气体比例气调包装的新鲜度变化

以黑鳍金枪鱼为对象,研究4℃条件下气调包装对其K值、pH值与感官品质的影响。结果表明:当气调包装的气体比例为CO_2∶N_2=60∶40(V/V)时,黑鳍金枪鱼保鲜时间最久,可达到96 h,且不会发生明显酸化;在冷藏条件下,K值可以从滋味、气味的角度很好地反映黑鳍金枪鱼的感官品质。     

鸡肉冷藏成熟过程中新鲜度和嫩度与肽含量关系

为研究冷藏成熟过程中鸡肉新鲜度和嫩度与肽含量的关系,以刚屠宰的鸡胸肉为研究对象,探究宰后鸡肉常规冷却与快速冷却过程中的肽含量与其感官评分、新鲜度和嫩度的相关性。结果表明：鸡肉中肽含量随冷藏时间的延长先下降后上升,在冷藏0.5 d时达到最低值,冷藏3 d后逐渐上升,且常规冷却组鸡肉肽含量极显著高于快速冷却组（P＜0.01）;鸡肉中总游离氨基酸含量与肽含量变化趋势相反;冷藏0.5 d后,随着冷藏时间的延长,鸡肉中肽含量与pH值、菌落总数及挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量同步上升,而剪切力及感官评分逐渐降低。快速冷却能够延长成熟的时间,有利于鸡肉贮藏保鲜。冷藏期间,2 组鸡肉中的肽含量与菌落总数、pH值和TVB-N含量呈显著或极显著正相关（P＜0.05、P＜0.01）,肽含量可用于评价鸡肉的新鲜度。     

不同质量分数NaCl和CaCl2盐溶液解冻对金枪鱼品质的影响

采用不同质量分数NaCl和CaCl2溶液对金枪鱼鱼块进行解冻,测定并分析解冻时间、a*值、盐溶性蛋白含量、质构等指标,并对解冻后金枪鱼鱼肉的微观组织结构进行观察比较,研究不同质量分数盐溶液解冻对金枪鱼品质的影响。结果表明：对于同类盐溶液,随着盐溶液质量分数增加,金枪鱼鱼块的解冻速率和渗盐量增加。经质量分数3%?CaCl2解冻后的金枪鱼鱼肉保水性、盐溶性蛋白含量较高,质构最理想,微观组织结构最完整。综上,采用质量分数3%?CaCl2解冻,能够减轻解冻过程对金枪鱼鱼肉的影响,维持金枪鱼的新鲜度。?     

冻藏罗非鱼片品质变化及其货架期预测模型的建立

本文分析了罗非鱼片在-18℃、-14℃和-10℃条件下贮藏的感官、微生物和理化等指标变化,从中选择一个敏感指标用于货架期预测模型的建立。结果显示,随着贮藏时间的延长,冻罗非鱼片的菌落总数对数值缓慢增长,在120 d时分别达到4.31log(CFU/g)、4.76 log(CFU/g)和5.47 log(CFU/g),均未达到国家规定的冻罗非鱼片菌落总数上限值。TVB-N值呈线性上升,分别在60d、80 d和120 d降至二级鲜度13 mg/100 g;TBA值逐渐升高,但各实验组间反应速率差异不显著。冻罗非鱼片的感官评分逐渐下降,但在贮藏末期仍保持着较好的感官品质。随贮藏温度越低,品质指标衰变越缓慢。运用Pearson相关系数对各品质指标进行分析,确定敏感指标为TVB-N,结合拟合优度分析结果判断TVB-N指标的变化符合零级反应。应用Arrhenius方程构建贮藏温度(T)与反应速率(ka)间的动力学方程,并以此为基础,推导得到恒定冷链温度条件下冻罗非鱼片货架期预测模型。在-10℃和-14℃下评价货架期预测模型可靠性,能够准确预测冻罗非鱼片的品质随温度的变化情况。     

臭氧水处理鲜切生菜贮藏期间的品质变化

研究了臭氧水处理鲜切生菜在 4℃贮藏期间的细菌总数、大肠菌群、PPO活性、Vc含量、失重率和感官质量的变化。试验结果表明 ,与对照相比 ,采用 0 1 8μg/L臭氧水处理可使鲜切生菜中细菌总数下将 1 5个数量级、大肠菌群数低于 3 0× 1 0 - 2 /g ,PPO活性被抑制、Vc损失减少 ,失重率降低 ,同时 ,贮藏至 9天 ,感官质量明显优于对照组。     

酸性电解水对采后龙眼果实贮藏期间活性氧代谢的影响

酸性电解水（acidic electrolyzed water,AEW）处理属于新型的果蔬采后保鲜方式。该实验探讨AEW处理对龙眼果实采后贮藏期间活性氧（reactive oxygen species,ROS）代谢的影响。结果表明：相比对照组,pH 2.5、有效氯质量浓度80 mg/L、氧化还原电位1 512 mV的AEW浸泡果实10 min能显著提高贮藏期间龙眼果肉抗氧化酶（抗坏血酸过氧化物酶、过氧化氢酶和超氧化物歧化酶）活性,保持较高水平的非酶抗氧化物质（如还原型谷胱甘肽和还原型抗坏血酸）含量,及较高的1,1-二苯基-2-三硝基苯肼自由基清除能力和还原力。此外,AEW处理可显著降低果肉超氧阴离子产生速率和过氧化氢含量（P<0.05）,从而有效抑制丙二醛含量的上升。据此推测,AEW处理增强龙眼果实的耐贮性可能与其提高采后贮藏期果肉的ROS清除能力紧密相关。     

Microbiological and Sensory Changes in Minced Beef Treated with Potassium Lactate and Sodium Diacetate during Refrigerated Storage

The effect of potassium lactate and sodium diacetate on the microbiological changes and sensory properties of vacuum-packaged minced beef was investigated. The meat samples both with a preservative (in the amounts 0.65% and 1.3%) and without were stored at temperatures of 0–1°C and 5–6°C. The influence of storage time on changes in total bacteria count (TBC), lactic acid bacteria (LAB), Brochothrix thermosphacta, and the microbes of the Enterobacteriaceae family was investigated, as well as changes in pH and sensory quality. It was found that the addition of the preservative to the minced meat caused a significant extension (p < 0.05) of the lag phase and an inhibition of microbial growth rate, depending on temperature, storage time, and its concentration. The antibacterial effect was significantly higher (p < 0.05) at a temperature of 0–1°C than at 5–6°C and most susceptible to it were the bacteria belonging to the Enterobacteriaceae. The study results showed that the minced beef containing the preservative which had been vacuum stored at 0–1°C, presented a better sensory quality and had a shelf-life of about 6 days longer, in relation to the quality and shelf-life of the control samples. For each of the refrigeration storage temperatures however, there was no statistically significant change (p < 0.05) in the pH for the various storage periods and preservative quantities present.     

水分调节协同微波处理米糠储藏期品质变化规律研究

本研究采用微波协同调节水分探讨了对米糠中酶活变化、储藏期米糠品质以及生理活性物质变化规律。结果表明：调节初始水分含量对微波稳定化米糠具有明显的协同增效作用,初始水分质量分数为24%时,过氧化物酶酶活为0,脂肪酶约为7%,多酚氧化酶约为3%;初始水分质量分数为24%,微波功率1000 W,微波时间180 s和料层厚度1.5 cm,米糠在12周储藏期时的酸价和过氧化值分别为21.45 mg KOH/g和4.22 mmol/kg,相比较原料（初始水分质量分数11%）,酸价降低约35%,过氧化值降低约26%;影响因素大小依次为：米糠初始水分含量>微波功率>微波时间＞料层厚度;生育酚和生育三烯酚总含量12周储藏期内线性下降趋近于0,只有在较高初始水分含量下第8周时出现阶段上升后再下降,微波处理对γ-生育酚和γ-生育三烯酚含量影响较大,平均降低50%和33%,较高初始水分含量处理的米糠α-生育三烯酚含量（200 mg/kg）较低;米糠油脂肪酸组成在储藏期内棕榈酸含量增加,油酸和亚油酸含量降低;谷维素含量出现先增加后下降的趋势,在8周时达到最大1.35%左右。水分调节对储藏期米糠脂肪酸组成和谷维素含量无显著性影响。综合考虑为了得到较好品质的米糠原料,储藏的时间不宜超过2周。     

Development of Biogenic Amines in Yellowfin Tuna (Thunnus albacares): Effect of Storage and Correlation with Decarboxylase-Positive Bacterial Flora

ABSTRACT: The effects of storage at 0,4,10, and 22°C for 0,1,3,5, and 9 d on the quality of yellowfin tuna fillets as determined by microbiological assessment, development of some biogenic amines, and sensory analysis were studied. Tuna fillets stored at 22 °C for 3 d, 10 °C for 5 d, and 4 °C for 9 d were rated unacceptable for consumption. Those stored at 22 °C for 3 d had total aerobic bacterial count of > 8 log₁₀ CFU/g, a histamine-producing bacterial population of 7 log₁₀ CFU/g, and 832 ppm of histamine, 35.8 ppm of putrescine, and 147 ppm of cadaverine. A comparison of the capillary electrophoresis, AOAC fluorometric method, and gas chromatography showed a very good correlation (r² > 0.99) among these 3 methods for histamine quantitation in tuna samples. Morganella morganii, Enterobacter agglomerans, Enterobacter intermedium, Pseudomonas fluorescens, Proteins vulgaris , and Serratia liquefaciens were the decarboxylase-positive bacterial species isolated by using the Niven's medium and identified during storage, which were responsible for histamine production in test tuna fillets.