Effect of Freezing Temperature and Duration on Physicochemical Characteristics of Instant Rice

Abstract

Instant rice is becoming more popular in modern lifestyle. This study investigated the effect of freezing temperature and duration on physicochemical characteristics of instant rice. Raw material used in this study was rice with two different amylose content, i.e. high (> 25%) and intermediate (20-25%). The experiment was conducted in randomized block design with treatments of freezing temperature (-20 and-4°C) and time (12, 18, and 24 hour), with three replications. The results of analysis of variance (ANOVA) showed that between freezing temperature and duration were significantly different of their physicochemical characteristics (p<0.05). The best freezing temperature and duration for both of rice was-4°C for 24 hour. Characteristics of instant rice from high amylose were rehydration time of 4.97 minutes, rehydration ratio of 3.14, density of 0.55 gr/ml, volume expansion of 178.99%, water absorption 55.44%, and yield recovery of 88.67%. This product contained of 6.57% moisture, 0.40% ash, 0.21% fat, and 7.92% protein. While, characteristics of instant rice from intermediate amylose were rehydration time of 4.07 minutes, rehydration ratio of 3.29, density of 0.57 gr/ml, volume expansion of 169.64%, water absorption 56.90%, yield recovery of 92.05%. This product contained of 7.58% moisture, 0.70% ash, 0.42% fat, and 7.92% protein.