Changes of physical and chemical properties of rice (cv. Mentikwangi) as affected by storage conditions

¹ Indonesia Centre for Agricultural Postharvest Research and Development (ICAPRD), IAARD-Ministry of Agriculture, Jakarta 12540, Indonesia
² Department of Food Industrial Technology, University of Padjadjaran, Bandung, Indonesia
³ Department of Food Technology, University of Pasundan, Bandung, Indonesia

^* Corresponding author: jomunarso@gmail.com

Abstract

The quality charcteristics of rice could be changed during storage caused by respiration and enzyme activity. The respiration process remains during storage, producing carbon dioxides, vapour, and heat. This study aimed to examine the changes in physical and chemical properties of rice (cv. Mentikwangi) for six months of storage. Rice samples were packed using plastic polypropylene and stored at ambient temperatures of 27-30 °C and 54-62% of humidity. Rice sampling was done four times, i.e., months 0, 2, 4, and 6. Observations were made on starch crystallinity, particle morphology, reducing sugars, amylose, glucose, and maltose. The SEM image and XRD data showed that rice starch was less rigid and more amorphous after four months. In addition, eating quality data showed that the rice had high swelling and needed more water. Amylographic also performed that rice samples were getting harder. Sugar and amylose reduction levels increased by 1.84% and 2.5%, respectively. Unlike both, around 7.94% of starch was reduced. The γ-amylase had broken the amylopectin chain according to the glucose content degradation and occurred naturally during the six-month storage period.