DRYING CHARACTERISTICS AND QUALITY OF PADDY EXPOSED TO INFRARED RADIATION

Abstract

Paddy is a vital staple food that provides the world's dietary energy supply, but its high moisture content challenges post-harvest management. Infrared radiation (IR) heating is a promising solution for drying paddy, with benefits such as uniform heating, reduced processing time, and improved product quality. This research evaluates the effect of different IR temperatures on the drying quality of paddy. IR experimental set-up was built using a 1000 W ceramic IR emitter and a ceramic plate. A temperature control system was developed with a Raspberry Pi 4 B and Python 3.7 programming language. The study used freshly harvested paddy (Bg 300 -length 8.22±0.01 mm, width 2.92±0.02 mm, thickness 2.05±0.01 mm) with an initial moisture content of 18.02±0.39% (wet basis). The paddy was dried at four different temperatures: 62.19±0.00°C, 81.91±0.01°C, 104.74±3.09°C and 131.62±3.22°C with respective exposure times 1380 s, 480 s, 150 s, and 120 s while maintaining a consistent bed thickness (11±0.82 mm) until the final moisture content was 12.36±0.09% (wet basis). The considered paddy quality assessment parameters were Head Rice Percentage (HRP), Total Milling Yield (TMY), and Whiteness Index (WI). ANOVA test was conducted using Minitab 19.1. The HRP values for temperatures 62.19°C, 81.91°C, 104.74°C and 131.62°C were 34.1±0.9%, 26.02±1.8%, 26.06±0.80% and 14.00±0.91%, respectively. The corresponding TMY values were 69.29±0.13%, 57.58±0.92%, 64.2±0.46%, 70.97±0.89% and WI values were 67.67±0.18, 68.28±0.895, 67.675±0.825 and 65.525±0.025. The results indicated that the drying temperature significantly affects (p≤0.05) HRP and WI but not the TMY of the paddy. Further, the results indicated that increasing the drying temperature reduces the time to obtain the required final moisture content. In conclusion, the time for drying paddy and the quality of paddy changes with different IR temperatures.