Babic I, Roy S, Watada A E, Wergin W P
Horticultural Crops Quality Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705-2350, USA.
Int J Food Microbiol. 1996 Aug;31(1-3):107-19. doi: 10.1016/0168-1605(96)00969-5.
The microbial populations found on fresh-cut spinach leaves that were stored in gas permeable bags at 10 degrees C for 12 days were examined and identified. The microorganisms consisted of mesophilic aerobic bacteria, psychrotrophic bacteria, Pseudomonadaceae, Enterobacteriaceae, Micrococcaceae, lactic acid bacteria and yeasts. Populations of mesophiles, psychrotrophs, Pseudomonadaceae and Enterobacteriaceae increased sharply during the storage period. The initial populations were 10(7), 10(6), 10(6) and 10(4) CFU.g-1 respectively. Populations reached 10(10) for the mesophiles, psychrotrophs and Pseudomonadaceae and 10(7) CFU.g-1 for Enterobacteriaceae after 12 days of storage. Micrococcaceae, lactic acid bacteria and yeasts remained constant (10(3)-10(4) CFU.g-1. The majority of the bacterial isolates were identified as Pseudomonas fluorescens, Aeromonas caviae and Staphylococcus xylosus. The yeasts, which were most frequently isolated, were classified in the genus Cryptococcus. No pathogens such as Listeria monocytogenes and Salmonella were detected. Observations with low temperature scanning electron microscopy (LTSEM) indicated that the microorganisms were not present on the surface of healthy unbroken leaves. Alternatively, they were found in areas where the cuticle was broken and could be seen infecting the internal palisade parenchyma.
对在10摄氏度下于透气袋中储存12天的鲜切菠菜叶上发现的微生物群落进行了检测和鉴定。这些微生物包括嗜温需氧菌、嗜冷菌、假单胞菌科、肠杆菌科、微球菌科、乳酸菌和酵母菌。嗜温菌、嗜冷菌、假单胞菌科和肠杆菌科的菌落在储存期间急剧增加。初始菌落数分别为10⁷、10⁶、10⁶和10⁴CFU·g⁻¹。储存12天后，嗜温菌、嗜冷菌和假单胞菌科的菌落数达到10¹⁰，肠杆菌科的菌落数达到10⁷CFU·g⁻¹。微球菌科、乳酸菌和酵母菌的数量保持恒定（10³ - 10⁴CFU·g⁻¹）。大多数细菌分离株被鉴定为荧光假单胞菌、豚鼠气单胞菌和木糖葡萄球菌。最常分离出的酵母菌被归类为隐球菌属。未检测到诸如单核细胞增生李斯特菌和沙门氏菌等病原体。低温扫描电子显微镜（LTSEM）观察表明，健康完整叶片表面不存在微生物。相反，它们出现在角质层破损的区域，并且可以看到正在感染内部栅栏薄壁组织。
