Combined ultrafiltration and ozone processing of sugarcane juice: Quantitative assessment of polyphenols, investigation of storage effects by multivariate techniques and shelf life prediction

Abstract

Sugarcane juice (SJ) is prone to rapid spoilage post-extraction that limits its storage and marketing. To address this problem, two non-thermal techniques, viz., ultrafiltration (UF) and ozone treatment (OZ) combinedly are attempted. Cumulative enzyme and microbial inactivation effects were obtained by combining the processes (UF-OZ) providing about 85% polyphenoloxidase, 91% peroxidase, 7 log bacteria and 5.2 log yeast and mold inactivation. The effects of processing on major phenolic acids, flavonoids and sensory properties were evaluated. From HPLC characterization, it was found that, caffeic acid (13.22 ppm) which was the most abundant accounting for 50.5% of the total evaluated phenolic acids reduced by 26.7% in processed SJ. Among flavonoids, vitexin and its derivatives (22.19 ppm) constituted the highest proportion (63.3%) of total evaluated flavones which did not decrease significantly (p>0.05) after processing. Principal component analysis (PCA) and hierarchical cluster analysis efficiently distinguished the stored samples and showed the dissimilarities in quality characteristics after 12 weeks of storage. PCA very well outlined the interrelationship status of quality parameters and spoilage indicators associated with browning and microbial degradation. The microbiological stability analysis using microbial growth (Gompertz) model confirmed that the ultrafiltered ozonised sugarcane juice could be safely stored up to 90 days under refrigeration.