Postmortem biochemical behavior of giant squid (Dosidicus gigas) mantle muscle stored in ice and its relation with quality parameters

ABSTRACT:  Several freshness and spoilage indicators were monitored to characterize the postmortem biochemistry of giant squid ( Dosidicus gigas ) mantle muscle. Squid samples were obtained directly from the sea and kept at 0 °C during a 15-d storage period. Data at zero time were obtained from cryogenically frozen samples at time of capture. The adenosine 5'-triphosphate (ATP) degradation followed a different pattern as compared with that from fish species. ATP was almost completely depleted at 24-h postcatch from 6.54 to <1 μmol/g, while at the same time Hx was the predominant catabolite with a concentration of 4 μmol/g, reaching 6.85 μmol/g at day 15. K -value data followed a logarithmic pattern with time instead of a linear one, with no change after day 3, thus reducing its suitability as a freshness index. The coefficient Hx/AMP seems to be an adequate alternative for this purpose due to its constant increment with time. The high NH₄Cl content in mantle muscle (461.3 ± 24.5 mg of NH₄⁺/100 g) derived from its physiological importance for the species compromises the use of the distillation step of the TVB-N analysis commonly used as a spoilage index. This fact explains why the initially high value of TVB-N detected in mantle muscle (243.7 mg N/100 g) did not correlate with the initial low TMA-N content (1.5 ± 0.1 mg/100 g of muscle). The results suggested that under the experimental conditions the shelf life of squid exceeds 15 d.     

鲜黄花菜衰老机制与采后贮藏保鲜技术研究进展

黄花菜是我国传统的特色蔬菜,具有较高的营养价值和经济价值,但是其采后极易衰老腐烂。本文系统综述了近年来有关鲜黄花菜衰老的生物学变化、生理生化代谢机制、影响因素及采后贮藏保鲜技术等方面的研究进展,为深入认识鲜黄花菜衰老机制、提高采后鲜黄花菜贮藏保鲜效果提供参考。     

硅窗气调对灵武长枣生理变化的影响

研究硅窗气调对灵武长枣贮藏中生理变化的影响,用不同的硅窗对灵武长枣处理,结果表明,使用5×5的硅窗袋进行气调,可以有效的保持灵武长枣的硬度以及VC含量,且能有效抑制乙醇的产生.经过这样处理的灵武长枣,其保质期可达到90d以上,好果率在94％以上.     

机械损伤对富士苹果生理生化变化的影响

研究了富士苹果受到机械损伤后在5℃和18℃2种贮藏温度下呼吸强度、可溶性固形物、乙烯释放量、果肉硬度、苯丙氨酸解氨酶活性和木质素含量的变化。结果表明:富士苹果受到机械损伤后,呼吸强度、乙烯释放量均明显提高,而且随着温度的升高而显著地升高;可溶性固形物含量和果肉硬度均快速下降;苯丙氨酸解氨酶活性略低于对照,但在贮藏初期也逐渐上升;木质素含量在贮藏前期快速下降,后期又逐渐上升。在贮藏过程中,除了木质素含量外,受伤果的其他各项指标都显示了上升、下降的反复趋势,说明受伤组织具有提高代谢水平,同时也促进了愈伤组织的形成,实现自我修复的功能。实验结果显示,低温贮藏有利于保持苹果的贮藏品质。     

减压对安哥诺李贮藏生理生化变化的影响

研究了减压对安哥诺李果实贮藏生理生化变化的影响。实验结果表明，减压有效保持了李果实的硬度和TSS含量，降低了果实中酸的消耗，抑制了果实呼吸强度和MDA含量的积累，保持了较高的SOD活性和较低的POD活性。从而延缓了果实的成熟衰老。     

气调包装对香菇保鲜期内源性甲醛含量的影响

对不同气调包装(MAP)的香菇甲醛含量与理化关系进行研究。研究结果表明:贮藏期间,香菇甲醛含量与GGT和C-Slyase两酶比活呈显著正相关(相关系数r分别为0.777和0.700),而GGT和C-Slyase酶活与香菇的呼吸强度呈显著正相关(相关系数r分别为0.539和0.701)。MAP能抑制酶活,控制甲醛含量,减缓香菇蛋白质的降解和相对膜透性的增高。贮藏前12d,3组MAP香菇的甲醛平均含量比对照低13.00%(P<0.01)。其中,MAP(1)(7%CO2)香菇的平均含水率和蛋白质含量比对照高2.23%和7.81%,细胞膜透性平均比对照低27.24%,3种含硫风味化合物相对含量分别比对照低16.23%以上,品质保鲜效果最佳。     

正向近冰点温度下肉牛骨骼肌主要生化指标变化特性的研究

本文对30头肉牛宰后经电刺激的胴体从背最长肌肉处取样在近冰点温度(1～-1℃)下贮存10d过程中游离Ca2+、ATP、总游离氨基酸、糖原、失水率的变化进行了研究。结果表明,10d中糖原、总游离氨基酸、ATP、失水率的变化几乎是同步的,均在刚宰后的0～1d(24h)中变化明显,第2d(48h)是转折点,而游离Ca2+第3d(72h)是转折点。作出了相应的变化曲线图,对指标间作Pearson相关性分析表明:游离钙与可溶性磷、游离钙与失水率、可溶性磷与失水率、糖原与总游离氨基酸、糖原与可溶性磷之间相关系数均极显著(p<0.01);游离钙与糖原之间相关系数显著(p<0.05);并且得出了相应的相关方程。对牛肉样的五项指标进行综合分析可知:所测定的牛肉样品在宰后约13.5h就进入了僵直起始阶段,而到宰后接近48h僵直达到了最大化。     

Combined biochemistry and histocytochemistry as a tool to investigate Ecto-ATPase in the cardiac muscle

Ecto-ATPase (ecto-adenosine triphosphatase), a key enzyme of cardiac metabolism, is responsible for modulation of the concentration of extracellular nucleotides in the heart. We present methodology consisting of the combined use of biochemical and histocytochemical techniques to study its properties. Using samples from essentially the same preparation, we applied biochemistry and histocytochemistry to determine biochemical characteristics of ecto-ATPase and an in situ localization of its reactivity. Our results indicated that detected enzyme resists fixation, depends on divalent ions, and hydrolyzes ATP, but not AMP or ADP-beta-S. Reaction product of the enzyme activity was found confined to the extracellular surface of the plasma membrane of cardiac myocytes and endothelial cells due to the corresponding orientation of the enzyme active sites. Experiments using an inhibitor justified specificity of the reaction. When used together with molecular biological and immunocytochemical techniques, the present methodological approach should be capable of yielding important information about the actual ability of ecto-ATPase to operate.     

A/O+BIOFOR处理生物化工废水

生物化工生产废水有机物浓度高,污染物质复杂,处理困难,文章介绍A/O BIOFOR组合工艺方法对其处理的工程实例.工程运行实践表明,该组合工艺处理效果好,运行稳定.各项指标均达到GB8978-1996《污水综合排放标准》的一级标准.     

高浓度抗生素制药废水的处理工艺

采用多级生化处理和混凝沉淀法组合工艺对抗生素制药废水进行试验研究。结果表明,经过多级生化处理后COD去除率可达到94．4%,NH3-N去除率可达到99％。该工艺具有处理效率高、耐冲击负荷强、运行稳定、操作管理简单等优点。