One pot two-alkali clarification process to minimize sucrose degradation of clarified sugarcane juice during evaporation

Abstract

Chemical degradation of sucrose during evaporation is a key production issue for the sugar cane industry. Although targeting higher juice pH using Lime Saccharate (LS) is commonly recommended to reduce sucrose degradation, this study showed reduced sucrose degradation occurs with increasing juice pH at the expense of higher invert sugar degradation and residual Ca2+ which could respectively lead to increase in juice colour and higher scaling propensity. The study also showed that Na+ and K+ ions have minimal effect on sucrose hydrolysis, while Ca2+ and Mg2+ increased the rate of sucrose hydrolysis through reducing juice pH and via complexation with the sucrose molecule. With this knowledge, a novel two-stage clarification method using a hybrid alkaline agent compared to LS was assessed for sucrose degradation and clarification performance. The results showed that LS/Mg(OH)2, LS/Na2CO3, LS/KOH and LS/NaOH showed lower sucrose degradation than the conventional LS method with up to 53% lower residual Ca2+ levels. LS/KOH and LS/NaOH achieved clarification performances comparable to the LS under the tested conditions while, LS/Mg(OH)2 and LS/Na2CO3 would further require further testing to improve clarification performance.