Department of Nutrition and Food Science, University of Maryland, College Park, MD, USA.
Foodborne Pathog Dis. 2013 Jan;10(1):87-96. doi: 10.1089/fpd.2012.1301. Epub 2012 Dec 20.
Foodborne outbreaks associated with the consumption of fresh produce have increased. In an effort to identify natural antimicrobial agents as fresh produce-wash, the effect of essential oils in reducing enteric pathogens on iceberg and romaine lettuce was investigated. Lettuce pieces were inoculated with a five-strain cocktail of Escherichia coli O157:H7 or Salmonella enterica (5 log CFU/g) and then immersed in a treatment solution containing 5 ppm free chlorine, cinnamaldehyde, or Sporan(®) (800 and 1000 ppm) alone or in combination with 200 ppm acetic acid (20%) for 1 min. Treated leaves were spin-dried and stored at 4°C. Samples were taken to determine the surviving populations of E. coli O157:H7, Salmonella, total coliforms, mesophilic and psychrotrophic bacteria, and yeasts and molds during the 14-day storage period. The effect of treatments on lettuce color and texture was also determined. Cinnamaldehyde-Tween (800 ppm, 800T) reduced E. coli O157:H7 by 2.89 log CFU/g (p<0.05) on iceberg lettuce at day 0; Sporan(®)-acetic acid (1000SV) reduced E. coli O157:H7 and Salmonella on iceberg and romaine lettuce by 2.68 and 1.56 log CFU/g (p<0.05), respectively, at day 0. The effect of essential oils was comparable to that of 5 ppm free chlorine in reducing E. coli O157:H7 and Salmonella populations on iceberg and romaine lettuce throughout the storage time. The natural microbiota on treated lettuce leaves increased during the storage time, but remained similar (p>0.05) to those treated with chlorine and control (water). The texture and the color of iceberg and romaine lettuce treated with essential oils were not different from the control lettuce after 14 days of storage. This study demonstrates the potential of Sporan(®) and cinnamaldehyde as effective lettuce washes that do not affect lettuce color and texture.
食源性疾病暴发与食用新鲜农产品有关的情况有所增加。为了寻找天然抗菌剂作为新鲜农产品洗涤液,本研究调查了精油对减少冰生菜和罗马生菜中肠病原体的效果。将生菜片用含有 5 株大肠杆菌 O157:H7 或沙门氏菌(5 对数 CFU/g)的鸡尾酒接种,然后浸入含有 5 ppm 游离氯、肉桂醛或 Sporan(®)(800 和 1000 ppm)的处理溶液中,单独或与 200 ppm 乙酸(20%)一起处理 1 分钟。处理过的叶子经过离心干燥并储存在 4°C。在 14 天的储存期间,取样品以确定大肠杆菌 O157:H7、沙门氏菌、总大肠菌群、中温菌和嗜冷菌以及酵母菌和霉菌的存活种群。还确定了处理对生菜颜色和质地的影响。肉桂醛-Tween(800 ppm,800T)在第 0 天减少了冰生菜上大肠杆菌 O157:H7 的数量达 2.89 对数 CFU/g(p<0.05);Sporan(®)-乙酸(1000SV)减少了冰生菜和罗马生菜上的大肠杆菌 O157:H7 和沙门氏菌数量,分别为 2.68 和 1.56 对数 CFU/g(p<0.05),在第 0 天。精油的作用与 5 ppm 游离氯在整个储存时间内减少冰生菜和罗马生菜上的大肠杆菌 O157:H7 和沙门氏菌的作用相当。在储存过程中,处理过的生菜叶片上的天然微生物群增加,但与用氯和对照(水)处理的微生物群相似(p>0.05)。经过 14 天的储存后,用精油处理的冰生菜和罗马生菜的质地和颜色与对照生菜没有区别。本研究表明,Sporan(®)和肉桂醛具有作为有效的生菜洗涤液的潜力,不会影响生菜的颜色和质地。