USDA, ARS, Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038, United States.
USDA, ARS, Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038, United States.
Int J Food Microbiol. 2018 Sep 2;280:57-65. doi: 10.1016/j.ijfoodmicro.2018.05.012. Epub 2018 May 12.
A study was conducted to evaluate the effects of post-treatment rinsing with water on the inactivation efficacy of acid treatments against Salmonella inoculated onto stem scar areas of two types of tomatoes. In addition, impact on fruit quality was investigated during 21 days post-treatment storage at 10 °C. A four-strain cocktail of Salmonella enterica (S. Montevideo, S. Newport, S. Saintpaul, and S. Typhimurium) was inoculated onto stem scar areas of grape and large round tomatoes. The inoculated fruits were then treated for 2 min with the following solutions: water, 2% lactic acid +2% acetic acid +2% levulinic acid, 1.7% lactic acid +1.7% acetic acid +1.7% levulinic acid, and 3% lactic acid +3% acetic acid. After treatments, half of the fruits were rinsed with water while another half were not rinsed. Non-inoculated grape tomatoes for quality analysis were treated with the same solutions with and without subsequent water rinse. Results demonstrated that the acid combinations reduced populations of Salmonella enterica on the stem scar area of grape tomatoes by 1.52-1.90 log CFU/fruit, compared with the non-treated control while water wash and rinse removed the bacterium by only 0.23-0.30 log CFU/fruit. On the stem scar of large round tomatoes, the same acid treatments achieved 3.54 log CFU/fruit reduction of the pathogen. The varying response to the acid washes between grape and large round tomatoes seems to be related to the differences in surface characteristics of stem scar areas observed with SEM. Rinsing with water after acid combination treatments did not significantly affect the efficacy of the treatments in either grape or large round tomatoes. Acidic off-odor was detected on fruits treated with acid combination without water rinse 1 day after treatment while water rinse eliminated the off-odor. The acid treatments with and without water rinse did not consistently affect appearance, color, firmness, or lycopene or ascorbic acid contents of tomatoes during 21-days storage at 10 °C. Considering the similarity in antimicrobial efficacy between the fruits with and without water rinse following acid treatments, and the elimination of acidic odor by water rinse, fruits should be rinsed with water after acid treatments. Overall, our results demonstrated that the acids were more effective in inactivating Salmonella on large round tomatoes than on grape tomatoes, and water rinses following acid treatments eliminated the acidic odor without affecting the efficacy of the acids against Salmonella.
一项研究评估了酸处理后用清水冲洗对两种类型番茄茎痕区接种的沙门氏菌灭活效果的影响。此外，还研究了在 10°C 下处理后 21 天的果实品质。将沙门氏菌（S. Montevideo、S. Newport、S. Saintpaul 和 S. Typhimurium）的四菌株鸡尾酒接种到葡萄和大圆形番茄的茎痕区。然后，用以下溶液处理接种的果实 2 分钟：水、2%乳酸+2%醋酸+2%戊酸、1.7%乳酸+1.7%醋酸+1.7%戊酸和 3%乳酸+3%醋酸。处理后，一半的果实用清水冲洗，另一半不冲洗。非接种葡萄番茄用于质量分析，用相同的溶液处理，有无后续水冲洗。结果表明，与未处理对照相比，酸组合将葡萄番茄茎痕区的沙门氏菌种群减少了 1.52-1.90 log CFU/个，而水洗和冲洗仅去除了 0.23-0.30 log CFU/个。在大圆形番茄的茎痕处，相同的酸处理使病原体减少了 3.54 log CFU/个。葡萄和大圆形番茄对酸洗液的反应差异似乎与 SEM 观察到的茎痕区表面特征的差异有关。酸组合处理后用清水冲洗不会显著影响葡萄或大圆形番茄中处理的效果。处理后 1 天，未经水洗的酸组合处理过的果实会产生酸性异味，而水洗则消除了异味。酸处理后用水冲洗不会持续影响番茄在 10°C 下储存 21 天的外观、颜色、硬度或番茄红素或抗坏血酸含量。考虑到酸处理后用清水冲洗和不冲洗的果实在抗菌效果上的相似性，以及水洗对酸性气味的消除，酸处理后应用水冲洗果实。总的来说，我们的研究结果表明，与酸处理后不用水冲洗的果实相比，酸处理在大圆形番茄上更有效地灭活沙门氏菌，并且酸处理后用水冲洗可以消除酸性气味，而不会影响酸对沙门氏菌的效果。
