Bhide Siddharth, Salvi Deepti, Schaffner Donald W, Karwe Mukund V
Department of Food Science, Rutgers, State University of New Jersey, 65 Dudley Road, New Brunswick, New Jersey 08901, USA.
J Food Prot. 2017 Aug;80(8):1337-1346. doi: 10.4315/0362-028X.JFP-17-064.
This study investigates the efficacy of cold atmospheric pressure plasma (CAPP) on microbial inactivation as influenced by surface roughness of two types of surfaces: sandpaper and fresh fruit peel. Different grits of closed-coat sandpaper were selected, with their roughness (P) values ranging from 6 to 16 μm. Apple, orange, and cantaloupe peels were selected for roughness values that were similar to the sandpapers. The sandpapers and the fruit peel surfaces were spot inoculated with Enterobacter aerogenes (10 CFU/63.64 cm) and exposed to CAPP for 492 s. Similar microbial enumeration techniques were used for both systems to quantify the microbial inactivation. The smoothest sandpaper showed a 0.52-log higher inactivation of E. aerogenes (2.08 log CFU/63.64 cm sandpaper surface inactivation) than did the roughest sandpaper (1.56 log CFU/63.64 cm sandpaper surface inactivation), and the difference was statistically significant (P < 0.05). The smoothest fresh fruit peel surface (apple) showed a 1.25-log higher inactivation of the microorganism (1.86 log CFU/63.64 cm fruit peel surface inactivation) than did the roughest fresh fruit peel surface (cantaloupe; 0.61 log CFU/63.64 cm fruit peel surface inactivation), and the difference was statistically significant (P < 0.05). As the surface roughness increased, microbial inactivation efficacy of CAPP decreased for both systems. The results from sandpaper show that, in a scenario in which the surface roughness was the only parameter of difference, the microbial inactivation efficacy of CAPP decreased with increasing surface roughness. The results from fruit surfaces show high variability and were not directly predictable from the sandpaper data. This suggests that the microbial inactivation efficacy of CAPP in real-world food systems, such as on fresh fruit peels, is affected by factors in addition to surface roughness.
本研究调查了冷大气压等离子体（CAPP）对两种类型表面（砂纸和新鲜果皮）的微生物灭活效果，这两种表面的粗糙度会对其产生影响。选择了不同粒度的封闭涂层砂纸，其粗糙度（P）值范围为6至16μm。选择苹果、橙子和哈密瓜的果皮，使其粗糙度值与砂纸相似。将产气肠杆菌（10 CFU/63.64 cm）点接种在砂纸和果皮表面，并使其暴露于CAPP下492秒。两个系统均使用类似的微生物计数技术来量化微生物灭活情况。最光滑的砂纸对产气肠杆菌的灭活效果（2.08 log CFU/63.64 cm砂纸表面灭活）比最粗糙的砂纸（1.56 log CFU/63.64 cm砂纸表面灭活）高0.52个对数，且差异具有统计学意义（P < 0.05）。最光滑的新鲜果皮表面（苹果）对微生物的灭活效果（1.86 log CFU/63.64 cm果皮表面灭活）比最粗糙的新鲜果皮表面（哈密瓜；0.61 log CFU/63.64 cm果皮表面灭活）高1.25个对数，且差异具有统计学意义（P < 0.05）。随着表面粗糙度的增加，两个系统中CAPP的微生物灭活效果均降低。砂纸的结果表明，在表面粗糙度是唯一差异参数的情况下，CAPP的微生物灭活效果随表面粗糙度的增加而降低。水果表面的结果显示出高度变异性，无法直接根据砂纸数据预测。这表明，在实际食品系统中，如新鲜果皮上，CAPP的微生物灭活效果除了受表面粗糙度影响外，还受其他因素影响。
