Increasing sugar recovery through improved mill sanitation and biocide application : final report 2020/203

Abstract

Undetermined sucrose loss during the processing of sugarcane to sugar is estimated between 1-2%, being a large financial loss to the industry. Microbial infection of sugarcane juice is from the microorganisms that enter the mill with the cane supply, and those from the floor washing and filtrate. Microbial degradation contributes 93% of the sucrose loss in mixed juice. Effective cleaning and sanitation procedures are needed to reduce microbial degradation in a factory. However, the hygiene practices vary among Australian mills. Biocides are not routinely used in Australian mills, though they are used overseas.

To provide the preferred corrective hygiene actions for sugar mills and to establish the effectiveness of using biocide in Australian mills, this project conducted audits at four mills to understand the habitat of the microorganisms and compared the effectiveness of two biocides to reduce microbial degradation in both laboratory and factory scales.

Results from the factory audits indicate that the floor recovery system stream has the highest microbial loading, and processing last cane and conducting hosing increases the microbial loading in juices. Laboratory biocide tests reveal that biocides could reduce the sucrose degradation rate in juices, and that the biocide P100 is more effective on FMJ, while P200 is more effective on SMJ. Factory trials indicate that using biocides could potentially reduce the polysaccharides and organic acids contents. Two new rapid analytical methods were developed for the analysis of sugars and sugar degradation products in a single run compared to established methods which multiple runs are required.