Debevere J, Boskou G
Department of Food Technology and Nutrition, Faculty of Agricultural and Applied Biological Sciences, University of Ghent, Belgium.
Int J Food Microbiol. 1996 Aug;31(1-3):221-9. doi: 10.1016/0168-1605(96)01001-x.
Cod fillets (Gadus morhua) were packed under modified atmospheres, with four different gas compositions (60% CO2-10% O2-30% N2, 60% CO2-20% O2-20% N2, 60% CO2-30% O2-10% N2, 60% CO2-40% O2), and stored at 6 degrees C. Plate counts were carried out after 3, 4, 5, 6 and 7 days, to follow the growth of aerobic and anaerobic bacteria, lactic acid bacteria, H2S-producing bacteria and Enterobacteriaceae. The production of total volatile bases (TVB) and trimethylamine (TMA), and the changes in pH of the fillets were measured. Modified atmosphere packaging (MAP) had in general an inhibitory effect on the growth of the microflora but limited inhibition of the production of TVB and TMA. Despite the fact that increased oxygen proportions in the atmosphere contributed in a slightly lower production of TMA, all the samples had a TVB and TMA content high enough to be considered as spoiled after 4 days' storage at 6 degrees C. A total aerobic plate count at 25 degrees C of a 10(6) cfu/g, combined with the presence of only a 10(3) cfu/g of H2S-producing bacteria, which are normally considered as TMAO-reducing organisms in fish, cannot explain the strong increase in TMA. A high cell concentration of more than 10(8) cfu/g of Shewanella putrefaciens is required for production of a TMA level normally found in spoiled fish. This suggests that there could be another type of bacterium in fish, not involved in the spoilage of unpacked fish, which is resistant to 60% CO2, is not H2S-producing, and shows a high TMAO-reducing capacity. This bacterium could be Photobacterium phosphoreum.
鳕鱼鱼片（大西洋鳕）在气调包装下，采用四种不同的气体组成（60%二氧化碳 - 10%氧气 - 30%氮气、60%二氧化碳 - 20%氧气 - 20%氮气、60%二氧化碳 - 30%氧气 - 10%氮气、60%二氧化碳 - 40%氧气），并在6℃下储存。在3、4、5、6和7天后进行平板计数，以跟踪需氧菌、厌氧菌、乳酸菌、产硫化氢细菌和肠杆菌科的生长情况。测定了总挥发性碱基（TVB）和三甲胺（TMA）的产生以及鱼片的pH值变化。气调包装（MAP）总体上对微生物的生长有抑制作用，但对TVB和TMA产生的抑制作用有限。尽管大气中氧气比例增加会使TMA的产生略有降低，但所有样品在在6℃下储存4天后，TVB和TMA含量都高到足以被认为已变质。在25℃下，10⁶ cfu/g的总需氧平板计数，再加上仅存在10³ cfu/g的产硫化氢细菌（通常被认为是鱼类中还原三甲胺氧化物的微生物），无法解释TMA的大幅增加。要产生通常在变质鱼类中发现的TMA水平，需要超过10⁸ cfu/g的腐败希瓦氏菌高细胞浓度。这表明鱼类中可能存在另一种细菌，它与未包装鱼类的腐败无关，对60%的二氧化碳具有抗性，不产生硫化氢，并且具有高三甲胺氧化物还原能力。这种细菌可能是发光杆菌。
