Effects of Low-Temperature Drying with Intermittent Gaseous Chlorine Dioxide Treatment on Texture and Shelf-Life of Rice Cakes

Timilehin Martins Oyinloye,Won Byong Yoon

doi:10.3390/pr8030375

Abstract

We investigated the effect of chlorine dioxide (ClO2) under low temperature drying to suppress rice cake stickiness during the cutting process by initiating the onset of retrogradation until the stickiness is minimized for shelf-life extension. The intermittent ClO2 application at low-temperature drying was conducted at 10 °C for different drying periods (0, 6, 12, 18, and 24 h). Texture analysis showed significant differences with increasing values of hardness (901.39 ± 53.87 to 12,653 ± 1689.35 g) and reduced values of modified adhesiveness (3614.37 ±578.23 to 534.81 ± 89.37 g). The evaluation of rice cake stickiness during the cutting process revealed an optimum drying period of 18 h with no significant difference (p ≤ 0.05) compared to the 24 h drying process. Microbial contamination during the drying process increased, with microbial load from 6.39 ± 0.37 to 7.94 ± 0.29 CFU/g. Intermittent ClO2 application at 22 ppm successfully reduced the microbial load by 63% during drying process. The inhibitory property of ClO2 was further analyzed on a sample with high initial microbial load (3.01 ± 0.14 CFU/g) using primary and modified secondary growth models fitted to all experimental storage temperatures (5–25 °C) with R2 values > 0.99. The model demonstrated a strong inhibition by ClO2 with microbial growth not exceeding the accepted population threshold (106 CFU/g) for toxin production. The shelf-life of rice cake was increased by 86 h and 432 h at room temperature (25 °C) and 5 °C respectively. Microbial inactivation via ClO2 treatment is a novel method for improved food storage without additional thermal sterilization or the use of an additional processing unit.

Highlights

Rice products are staple foods, especially in Asia with more than 50% of the population depending on rice as the primary source of dietary calories [1]
The inhibitory property of ClO2 was further analyzed on a sample with high initial microbial load (3.01 ± 0.14 CFU/g) using primary and modified secondary growth models fitted to all experimental storage temperatures (5–25 ◦ C) with R2 values > 0.99
This study validated the effect of intermittent ClO2 treatment during low-temperature drying to reduce the stickiness of rice cake during cutting and decrease the microbial load, resulting in extension of shelf-life by 86 h and 432 h during storage at room temperature (25 ◦ C) and 5 ◦ C, respectively

Summary

Introduction

Rice products are staple foods, especially in Asia with more than 50% of the population depending on rice as the primary source of dietary calories [1]. Rice products have many unique attributes, such as ease of digestion, bland taste, and hypoallergenic properties [2]. Many popular oriental foods, such as rice pasta, rice noodles, rice starch, and rice cakes are rapidly growing home meal replacements (HMR) in the market space due to their ease of access and short re-cooking periods [3]. Starch retrogradation is another important physicochemical phenomenon involved in cooked rice or rice-cake products. Retrogradation is caused by the recrystallization of amylose and amylopectin in starch-based foods. In the presence of water, amylose and amylopectin are swollen and gelatinized. The gelatinized amylose and amylopectin are reorganized into a more ordered structure by hydrogen bonding [4,5]

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