Effect of using different clarifying agents and temperature on physicochemical and sensory properties of sweet sorghum syrup extract

Abstract

The utilization of sorghum crops to produce value-added products such as alternative natural sweeteners has been increasing. Knowledge of the sweet sorghum juice clarification process to yield sweet sorghum syrup as an alternative sweetener is essential to get the best result and improve the quality of the syrup. This research aimed to study the sorghum syrup extraction process by using clarifying agents: Ca(OH)2, bentonite, and activated carbon, followed by the heating process at 70oC or 80oC. Sorghum stalks were milled to produce sorghum juice then clarified and heated up to make sweet sorghum syrup to reach 68.78-76.78% Bx. The clarification process was done to reduce particles in sorghum juice before the heating process. In this work, the psycho-chemical (pH, colour, turbidity, reducing sugar) and sensory properties (flavour and aroma) of sorghum syrup after clarification and heating process were analyzed. A randomized block design was used as the experimental design. Adding Ca(OH)2 and heating at 80oC resulted in sorghum syrup with higher pH and lower turbidity than that heated at 70oC. The evaluation revealed that the combination of Ca(OH)2 and 5% bentonite has the sweetest flavour, caramel aroma, and preferred psycho-chemical properties showed in pH (5.28), turbidity (35.56 NTU), and reducing sugar (57.52%).