Application of atmospheric cold plasma for inactivation of foodborne enteric pathogens on raw and dry roasted pistachio kernels and in pineapple juice
Date
2022-05
Authors
Hartanto, Verilyn
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Mendonca, Aubrey
Dickson, James
Coleman, Shannon
Brehm-Stecher, Byron
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Abstract
Tree nuts and fruit juices are nutritious and popular food products. In the food industry, tree nuts are usually dry roasted, and juices are pasteurized to ensure microbial safety. Those treatments rely on heat, which can alter food quality. Non-thermal treatments are gaining much attention from the food processors because they can inactivate pathogenic and spoilage microorganisms without the use of heat; therefore, food quality can be preserved. High voltage atmospheric cold plasma (HVACP) is a novel non-thermal technology that utilizes atmospheric air and pressure to inactivate microorganisms. In the present work, the antimicrobial effect of HVACP on inoculated pistachios and pineapple juice was investigated along with changes in selected quality attributes of those food products. Raw and dry roasted pistachios were inoculated with Salmonella enterica (7 log CFU/g) and treated with direct HVACP (80 kV) for 0 (control), 4, 8, 12, 16, and 24 min followed by storage at ambient temperature (22 ± 1ᵒC) for 24 h. Pineapple juice was inoculated with S. enterica and E. coli O157:H7 (7 log CFU/mL) and treated with direct HVACP (80 kV) for 0 (control), 1, 2, 3, and 4 min followed by 1 h and 24 h post-treatment storage at 4ᵒC. HVACP treatment for 24 min was able to decrease S. enterica survivors by 1.44 and 1.53 log CFU/g in raw and dry roasted pistachios, respectively. HVACP for 4 min followed by 1 h post-treatment storage reduce S. enterica and E. coli O157:H7 by 3.74 and 4.61 log CFU/mL, respectively, in pineapple juice. In contrast, no survivors were recovered from the HVACP-treated juice that was stored for 24 h. Sub-lethally injured pathogens were detected on HVACP-treated raw and dry roasted pistachios and only in pineapple juice, which was stored for 1h after treatment. Differences in percent sub-lethal injury in pathogen survivors on raw and dry roasted pistachios were not significant (p > 0.05). In pineapple juice, sub-lethal injury in E. coli O157:H7 survivors was significantly higher than that in S. enterica survivors (p < 0.05). The HVACP treatment did not affect the color and texture of both types of pistachios kernels. However, changes in absorbance, pH, and degrees brix were observed on the pineapple juice samples. Despite changes in absorbance, differences in the color of control and HVACP-treated juice were indistinguishable by visual observation. Overall, HVACP has good potential for use as a non-thermal treatment for improving the microbial safety of pistachios and pineapple juice.
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