Drying and Tempering Influence on the Milling Quality of Parboiled Rice

Abstract

Rice occurrence and dealings are features of the tradition of Bangladesh’s populace. However, their experience of parboiled paddy for domestic consumption is limited. Proper drying and tempering are very important for maximum milling output. The study was conducted to investigate the drying and tempering influence on the milling quality of parboiled paddy. The sample size of the paddy was 36 kg as per treatment. In the case of T1 (daily 4 hours sun drying) and T2 (daily 5 hours sun drying), 1-hour drying and 1/2 hour tempering were maintained, and for T3 (daily 4 hours sun drying) and T4 (daily 5 hours sun drying), 1-hour drying, and 1-hour tempering were maintained. The temperature of the paddy sample was varied from 18 °C to 42 °C in five treatments. Drying over three days at different time intervals led to reduced moisture content (from 23.42% to 9.24%), resulting in increased kernel hardness for reduced breakage during milling. The highest kernel strength after three days of drying was found to be 50.65 N/m for T4. The relative humidity, day temperature, air flow velocity, and solar radiation varied from 48% to 78%, 24 °C to 29 °C, 0.00 to 0.70 m/s, and 64450 to 108100 lux, respectively. Based on milled rice, the best milling output and head rice recovery were found to be 20.51 kg and 19.80 kg, respectively, for T4. The lowest quantity of broken rice was 0.50 kg found for T1 and T4, respectively. The lowest quantity of loss was 1.10 kg for T2, and the lowest quantity of husk and bran was 6.88 kg for T4. Results showed that among the five treatments, 5 hours of sun drying daily, maintaining the procedure of 1-hour drying and 1-hour tempering until the moisture content is reduced to 10% (T4), is more effective for increasing milling recovery.