Brar Pardeepinder K, Proano Lisseth G, Friedrich Loretta M, Harris Linda J, Danyluk Michelle D
Department of Food Science and Human Nutrition, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850, USA.
Department of Food Science and Technology, University of California, Davis, One Shields Avenue, Davis, California 95616, USA.
J Food Prot. 2015 Feb;78(2):323-32. doi: 10.4315/0362-028X.JFP-14-327.
Cocktails of lawn-collected cells were used to determine the survival of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes on the surface of raw peanut and pecan kernels. Kernels were inoculated with mixtures of four to five strains at 3 or 6 log CFU/g, dried at room temperature, and then stored at -24 ± 1, 4 ± 2, and 22 ± 1°C for 28 or 365 days. In most cases, rates of decline of the pathogens did not differ significantly between the two inoculum concentrations in the 28-day study. At 6 log CFU/g, populations of all pathogens were reduced by 0.5 to 1.6 log CFU/g during an initial 3-day drying period on both peanuts and pecans. The moisture content of peanuts and pecans remained stable at -24 ± 1 and 22 ± 1°C; at 4 ± 2°C, the moisture content increased from 3.8 to 5.6% on peanuts and from 2.6 to 3% on pecans over 365 days. Pathogen populations were stable on pecans stored under frozen and refrigerated conditions, except for L. monocytogenes, which declined at a rate of 0.03 log CFU/g/30 days at 4 ± 2°C. Salmonella populations were stable on peanuts stored at -24 ± 1 and 4 ± 2°C, but E. coli O157:H7 and L. monocytogenes declined at rates of 0.03 to 0.12 log CFU/g/30 days. At 22 ± 1°C, Salmonella, E. coli O157:H7, and L. monocytogenes declined at a rate of 0.22, 0.37, and 0.59 log CFU/g/30 days, respectively, on peanuts, and at 0.15, 0.34, and 1.17 log CFU/g/30 days, respectively, on pecans. Salmonella counts were above the limit of detection (0.30 log CFU/g) throughout the study. In most cases during storage, counts obtained from pecans were higher than from peanuts.
采用从草坪收集的细胞混合菌液来测定沙门氏菌、大肠杆菌O157:H7和单核细胞增生李斯特菌在生花生仁和山核桃仁表面的存活情况。将果仁接种四到五种菌株的混合物，接种浓度为3或6 log CFU/g，在室温下干燥，然后分别在-24±1℃、4±2℃和22±1℃下储存28天或365天。在大多数情况下，在为期28天的研究中，两种接种浓度下病原体的下降速率没有显著差异。接种浓度为6 log CFU/g时，在花生仁和山核桃仁最初3天的干燥期内，所有病原体的数量均减少了0.5至1.6 log CFU/g。花生仁和山核桃仁的水分含量在-24±1℃和22±1℃下保持稳定；在4±2℃下，365天后花生仁的水分含量从3.8%增加到5.6%，山核桃仁的水分含量从2.6%增加到3%。除单核细胞增生李斯特菌外，在冷冻和冷藏条件下储存的山核桃上病原体数量稳定，单核细胞增生李斯特菌在4±2℃下以0.03 log CFU/g/30天的速率下降。沙门氏菌数量在-24±1℃和4±2℃下储存的花生上保持稳定，但大肠杆菌O157:H7和单核细胞增生李斯特菌以0.03至0.12 log CFU/g/30天的速率下降。在22±1℃下，沙门氏菌、大肠杆菌O157:H7和单核细胞增生李斯特菌在花生上分别以0.22、0.37和0.59 log CFU/g/30天的速率下降，在山核桃上分别以0.15、0.
