Effect of human massage and machine stirring processes on dehydration correlating physical texture of white radish

Abstract

The present work examines the effect of salting on the drying characteristics and quality of white radish for preservation; the findings can be useful in replacing human labor for a community enterprise of Banka district, Ratchaburi Province, Thailand. The preservation of fresh white radish using salting and sun drying can extend storage duration and add value to the product. The traditional process consists of hand massage for 1 h/day, sun drying for 6 h/day, and keeping it in plastic sack for overnight (17 h/day) to remove moisture until the weight of the product is less than 40% of the initial weight. The machine stirrer decreased moisture content in radishes faster than that of traditional human force because water inside radish moves out quickly with the osmotic pressure gradient to establish equilibrium with salt solution. With the increased rotating speed of the machine increases, the hardness of radishes gradually decreases. The optimum conditions for stirring machine were observed at 50 rpm for 1 h/day to keep their hardness over 80 newtons. The properties of salted radish from stirring machine are as follows: 11.8 wt% of salinity, 0.80-0.85 of water activity, 63 to 65 of brightness value, and 80-85 newtons of texture hardness; these properties are similar to processing radish with hand massage method. Based on the findings, this research recommends investing in a solar dryer along with machine stirrer to reduce more moisture content, prevent dust contamination, decrease the number of stirring sessions; thus, reducing drying time.