Research and Development Division, World Institute of Kimchi, Gwangju, 61755, Republic of Korea.
Research Institute for Agricultural and Life Sciences, and Department of Agricultural Biotechnology, Center for Food and Bioconvergence, Seoul National University, Seoul, Republic of Korea.
Sci Rep. 2019 Feb 20;9(1):2400. doi: 10.1038/s41598-019-38987-9.
This study was conducted to investigate the effect of salt content during radio-frequency (RF) heating on rate of temperature increase, dielectric properties (DPs), and reduction of pathogens in pistachios. Also, the effect of RF heating on pistachio quality of varying salt content was determined. Pistachios of different salt content (0, 100, and 330 mg sodium/serving) were inoculated with Salmonella enterica and treated in a 27.12-MHz RF heater. The RF heating rate increased when salt content was in the range of 0-100 mg sodium/serving, but there were no significant (P > 0.05) differences in the rate of temperature rise after salt content reached to 100 mg sodium/serving. Both dielectric constant and dielectric loss factor of pistachios increased with rising salt content. Along with increased salt content, RF treatment time required to reduce this pathogen by 4 log CFU/g decreased first and then remained the same above an upper limit of salt content corresponding to the peak heating rate. RF treatment did not significantly (P > 0.05) cause changes in the color and level of lipid oxidation of pistachios. The results of the current study imply that RF heating may be a potential intervention for inactivating foodborne pathogens in pistachios and that the effect of pasteurization is influenced by dielectric loss factor relative to salt content.
本研究旨在探讨射频（RF）加热过程中盐含量对升温速率、介电性能（DPs）和开心果中病原体减少的影响。此外，还确定了 RF 加热对不同盐含量的开心果品质的影响。将不同盐含量（0、100 和 330mg 钠/份）的开心果接种沙门氏菌，并用 27.12MHz 的 RF 加热器进行处理。当盐含量在 0-100mg 钠/份范围内时，RF 加热速率增加，但当盐含量达到 100mg 钠/份后，升温速率没有显著差异（P＞0.05）。开心果的介电常数和介电损耗因子随盐含量的增加而增加。随着盐含量的增加，将这种病原体减少 4 个对数 CFU/g 所需的 RF 处理时间先减少，然后在盐含量超过与峰值加热速率对应的上限时保持不变。RF 处理对开心果的颜色和脂质氧化水平没有显著影响（P＞0.05）。本研究的结果表明，RF 加热可能是一种潜在的干预措施，可以使开心果中的食源性病原体失活，而巴氏杀菌的效果受到相对盐含量的介电损耗因子的影响。
