Effect of paddy final moisture content on grain hardness and milling properties of three rice varieties.
2012
Alizadeh, Mohammad Reza | Saboori, Samad | Habibi, Fatemeh | Haghtalab, Didar
In order to reduce rice losses and increase in head rice yield (HRY) in the milling process, it is very important to determine the appropriate final paddy moisture content after drying stage. In this research, the effect of two factors; four levels of final paddy moisture content (6, 8, 10 and 12 %w.b.) and three rice variety (Hashemi, Khazar and Kados) on the grain hardness (the maximum compressive fracture force), head brown rice yield (HRYbr), head rice yield (HRY) and milling recovery was studied. A factorial design based on randomized completely design with four replications was used for data analysis. The results revealed that the fracture (breakage) force decreased significantly (p0.01) from 146.66 to 113.51 N, 150.31 to 113.86 N and 150.49 to 101.93 N for Hashemi, Khazar and Kados varieties, respectively, as the final paddy moisture content increased from 6 to 12 %w.b. Similar trend was observed for the fracture force of brown rice. However, at each level of the tested moisture content and variety, the fracture force of paddy grain was higher than that of the brown rice. The HRYbr and HRY increased with decrease in paddy moisture content, so that for all the three rice varieties, the highest HRYbr and HRY was obtained at final moisture content of 6 % and the lowest values was registered at moisture content of 12%. There was a significant negative correlation between the paddy final moisture content and fracture force and HRYbr as well as HRY. Key words: Paddy moisture content, grain hardness, head rice yield, milling recovery
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