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首页> 外文期刊>Applied Microbiology >Changes in the Microflora of Haddock Fillets and Shucked Soft-Shelled Clams After Irradiation with Co60 Gamma Rays and Storage at 0 C and 6 C
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Changes in the Microflora of Haddock Fillets and Shucked Soft-Shelled Clams After Irradiation with Co60 Gamma Rays and Storage at 0 C and 6 C

机译：Co60γ射线辐照并在0 C和6 C储存后，黑线鱼鱼片和去壳的蛤的微生物区系的变化

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Frequency distribution patterns of aerobic-facultative microflora, obtained by random selection of macrocolonies from samples of haddock fillets and shucked soft-shelled clams before and after treatment with doses of from 50,000 to 800,000 rad of Co60 gamma rays, are presented, with analyses and interpretation. The data showed that a decided change occurred in the constitution of the microbial populations of both products: from a mixed gram-negative—gram-positive flora to a predominantly gram-positive flora immediately after irradiation. The great majority of these surviving microorganisms were micrococci, sporeforming bacilli, and certain yeasts, molds, and actinomyces. During storage at refrigeration temperatures above freezing, the microflora changed from the descendants of the more radioresistant gram-positive species to the more prolific gram-negative psychrophilic species that flourish at these low temperatures. Micrococci and gram-positive rods declined somewhat during the rise of the actively proteolytic-lipolytic pseudomonads and related species, but still remained at high enough levels to contribute significantly to the spoilage observed at different times in storage. The eventual spoilage of haddock fillets was characterized by discoloration of the cream-white tissue with water-soluble yellow, green, and red bacterial pigments; degradation of the tissue, by proteolytic and other microbial enzymes, to a watery, flaccid mass; and formation of volatile compounds that smelled putrid, rancid, and generally foul and pungent. Shucked soft-shelled clams displayed a different spoilage pattern, changing to a variegated brown-gray and forming a matted or loose gelatinous mass from which arose stale, acrid, putrid, sulfurous odors. These differences are believed to be attributable to the varied biochemical nature of the tissues involved, the Eh potential within the tissues, the time sequence of microfloral change, and the species and types of microorganisms associated with each product. Staphylococci were present in small numbers in some of the samples tested, but did not appear to be species of public health significance. Gram-negative enteric rods were also encountered, but were considered to be of doubtful public health importance. More detailed investigations, designed to study the effects of Co60 gamma radiations on such microbes in sea foods, would be useful in assessing the problem further.
机译：呈现了有氧兼性微生物群的频率分布模式，该模式是通过在50,000至800,000 rad的Co60γ射线剂量处理之前和之后从黑线鳕鱼片和去壳的蛤lam样本中随机选择大菌落而获得的，并进行了分析和解释。数据表明，两种产品的微生物种群结构发生了确定的变化：辐照后立即从混合的革兰氏阴性菌和革兰氏阳性菌群转变为主要的革兰氏阳性菌群。这些存活的微生物中绝大多数是微球菌，芽孢杆菌和某些酵母，霉菌和放线菌。在高于冰点的冷藏温度下储存期间，微生物区系从抗辐射性更强的革兰氏阳性物种的后代变成了在这些低温下繁盛的生产力更高的革兰氏阴性嗜冷物种。在活性蛋白水解-脂解性假单胞菌和相关物种的兴起期间，微球菌和革兰氏阳性棒有所下降，但仍保持足够高的水平，以显着促进在储存的不同时间观察到的腐败。黑线鳕鱼片最终变质的特征是乳白色组织被水溶性的黄色，绿色和红色细菌色素变色。通过蛋白水解酶和其他微生物酶将组织降解为水状，松散的团块;并形成挥发性化合物，散发出腐烂，腐臭的味道，并且通常具有臭味和刺激性。剥壳的蛤c表现出不同的腐败模式，变成杂色的棕灰色，形成无光泽或散乱的凝胶状物质，从中散发出陈旧，刺激，腐烂，含硫的气味。认为这些差异可归因于所涉及的组织的变化的生化性质，组织内的Eh电位，微生物菌落变化的时间序列以及与每种产品相关的微生物的种类和类型。在某些测试样品中葡萄球菌数量很少，但似乎不是具有公共卫生意义的物种。还遇到了革兰氏阴性肠棒，但被认为对公共卫生的重要性令人怀疑。旨在研究Co60γ射线对海鲜中此类微生物的影响的更详细的研究将有助于进一步评估该问题。

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