Effect of Different Crushing Treatments on Sweet Sorghum Juice Extraction and Sugar Quality Traits in Different Seasons

Abstract

Sweet sorghum (Sorghum bicolor (L.) Moench) is an important biofuel crop that produces both food (grain) and biofuel (from stalk juice). The objective of this investigation was to assess the effect of different crushing treatments on juice extraction and sugar quality traits of sweet sorghum cultivars grown in different seasons. Three sweet sorghum cultivars along with three stalk crushing treatments namely (i) stalk only crushed (leaf, sheath and panicle removed), (ii) stalk plus sheath crushed (leaf and panicle removed), and (iii) whole plant crushed (but only panicle removed) were assessed in split–split-plot design during 2009 rainy (Kharif) and 2009 post-rainy (Rabi) seasons. The percent juice extraction and juice sugar quality traits were significant (P< 0.05) in different crop seasons, but were non-significant among cultivars and crushing treatments. Sweet sorghum cultivars grown during rainy season had significantly higher total soluble sugars (TSS), sucrose and purity per cent than in post-rainy season. Experimental variety SPSSV 30 showed significant superiority by 25 % in TSS and sucrose content than check namely CSH 22SS. Effect of crushing treatments on juice extraction and sugar quality traits were non-significant except juice brix. It is recommended that the complete sweet sorghum stalks after removing the panicle can be crushed without the need for removing leaf and sheath both in large research trial samples, and bulk harvested stalks at biofuel processing facility. This will reduce processing time at the sugar mill and helps avoiding rapid deterioration of stalk sugars in the ambient field condition, as removal of leaf and sheath in sweet sorghum is highly cumbersome unlike sugarcane, where it is relatively easy.