Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

Application of radio frequency pasteurization process to almond kernels: Heating uniformity improvement

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2018 ASABE Annual International Meeting  1800526.(doi:10.13031/aim.201800526)
Authors:   Rui Li, Xiaoxi Kou, Xu Zhou, Lihui Zhang, Shaojin Wang
Keywords:   Almond kernels; E. coli ATCC 25922; Heating uniformity; Pasteurization; Quality; Radio frequency

Abstract. The efficacy of radio frequency (RF) treatment to inactivate E. coli ATCC 25922 used as a surrogate of pathogenic Salmonella in almond kernels was investigated. A pilot-scale, 27 MHz, 6 kW RF unit was used to study the heating uniformity of almond kernels at the moisture content of 10.01% w.b. using two types of plastic containers. Pasteurization processes were developed and validated for almond kernels and the product quality after RF treatments was evaluated. The results showed that only 6.4 min was needed to raise the central temperature of 1.5 kg almond kernels from 25°C to 72°C by using RF energy as compared to 276 min using 72°C hot air in a five-layer container. An effective RF treatment protocol was obtained using an electrode gap of 11 cm, 72°C hot air surface heating, intermittently rearranging the five-layers in less than 1 min, and holding in 72°C hot air for 15 min for pasteurization to achieve more than 4-log reductions of E. coli ATCC 25922, drying to reduce the moisture level, and cooling in the single layer by forced room air to avoid product quality degradation. The moisture content, fatty acid, peroxide value and color values of RF treated almond kernels met the good quality standard used by almond industry. Therefore, RF treatments are an effective and rapid heating method for potentially pasteurizing Salmonella in almond kernels.

(Download PDF)    (Export to EndNotes)