Radiofrequency-assisted low-temperature long-time (LTLT) pasteurization of onion powder
2022
Liu, Shuxiang | Xiong, Haitao | Qiu, Yan | Dai, Jianwu | Zhang, Qing | Qin, Wen
Recent outbreaks associated with Salmonella in low-moisture foods (LMFs) have urged the necessity to design and implement the pasteurization process. Sugar-rich LMFs, such as dates, confections, and some spices, may show severe quality loss due to the sugar phase transitions and Maillard reactions at elevated temperatures. Low-temperature long-time (LTLT) pasteurization can potentially eliminate pathogens in sugar-rich LMFs without compromising the products' quality. Here, we chose onion powder (water activity 0.32 ± 0.01, moisture content 7.4 ± 0.1%, w.b.); studies documented its foodborne pathogen contamination. Isothermal inactivation studies of Salmonella enterica Enteritidis PT 30 (S. Enteritidis) in onion powder were conducted at 60 °C, 65 °C, and 70 °C. An orthogonal experimental design optimized the radiofrequency (RF) heating parameters of 500 g onion powder. We accomplished the microbial validation study with RF-assisted hot-air pasteurization and assessed the quality changes before and after the process. The cold spot of RF-heated onion powder reached 66 °C within 180 s. We obtained a 3.4-log reduction of S. Enteritidis at 38 h of LTLT treatment, whereas only 2.10-log reductions were obtained in the control group. No significant quality loss was observed in onion powder after the process.
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