Lamb Jennifer L, Gogley Jennifer M, Thompson M Jasmine, Solis Daniel R, Sen Sumit
US Food and Drug Administration, Pacific Regional Laboratory Southwest, Los Angeles, California 90015, USA.
J Food Prot. 2002 Nov;65(11):1800-5. doi: 10.4315/0362-028x-65.11.1800.
Staphylococcus aureus is a common pathogen that causes foodborne illness. Traditional methods for controlling S. aureus do not address postprocess contamination. Low-dose gamma irradiation is effective in reducing pathogens in a variety of foods and may be effective in reducing S. aureus in ready-to-eat foods. The effects of gamma irradiation on product packaging should also be considered. The objective of this study was to determine the effects of gamna irradiation on product packaging and on S. aureus in ready-to-eat ham and cheese sandwiches. The effects of refrigerated storage on irradiated and nonirradiated sandwiches were also investigated. Ham and cheese sandwiches were inoculated with 10(6) or 10(7) CFU of S. aureus per g, frozen, irradiated, and analyzed by a standard plate count method. D10-values, the amount of irradiation needed to elicit a 1-log10 reduction of bacteria, were calculated. In addition, irradiated sandwiches were analyzed after 1, 13, 27, and 39 days of storage at 4 degrees C. The integrity of postirradiated packaging material was analyzed using Fourier transform infrared (FTIR) spectroscopy. Two experiments yielded D10-values of 0.62 and 0.63. During refrigerated storage, sandwiches irradiated with 5.9 kGy showed no S. aureus growth at any time; sandwiches irradiated with 3.85 kGy showed a 6.18-log reduction in S. aureus after 13 days; and nonirradiated sandwiches showed a 0.53-log increase in S. aureus after 39 days. FTIR spectroscopy showed that the label side and the bulge side were composed of polyethylene terephthalate and nylon 6, respectively. No significant change in the packaging due to irradiation was detected. In this study, low-dose gamma irradiation was shown to be an effective method for reducing S. aureus in ready-to-eat ham and cheese sandwiches and proved to be more efficacious than refrigeration alone. Additionally, package integrity was not adversely affected by gamma irradiation.
金黄色葡萄球菌是一种常见的导致食源性疾病的病原体。控制金黄色葡萄球菌的传统方法无法解决加工后污染问题。低剂量伽马射线辐照能有效减少各类食品中的病原体，可能对即食食品中的金黄色葡萄球菌也有减少作用。还应考虑伽马射线辐照对产品包装的影响。本研究的目的是确定伽马射线辐照在即食火腿和奶酪三明治中对产品包装及金黄色葡萄球菌的影响。同时也研究了冷藏对辐照和未辐照三明治的影响。将每克含有10(6)或10(7)CFU金黄色葡萄球菌的火腿和奶酪三明治进行接种、冷冻、辐照，然后用标准平板计数法进行分析。计算D10值，即使细菌数量减少1个对数10所需的辐照量。此外，对在4℃下储存1、13、27和39天后的辐照三明治进行分析。使用傅里叶变换红外(FTIR)光谱分析辐照后包装材料的完整性。两个实验得出的D10值分别为0.62和0.63。在冷藏期间，接受5.9千戈瑞辐照的三明治在任何时候都未出现金黄色葡萄球菌生长；接受3.85千戈瑞辐照的三明治在13天后金黄色葡萄球菌数量减少了6.18个对数；未辐照的三明治在39天后金黄色葡萄球菌数量增加了0.53个对数。FTIR光谱显示，标签面和鼓起面分别由聚对苯二甲酸乙二酯和尼龙6组成。未检测到辐照导致包装有显著变化。在本研究中，低剂量伽马射线辐照被证明是减少即食火腿和奶酪三明治中金黄色葡萄球菌的有效方法，且比单独冷藏更有效。此外，包装完整性未因伽马射线辐照而受到不利影响。
