Evaluation of freeze-concentrated sugar-cane juice

W.M. Lo, L.S.T. Chua, Abbas Fadhi Al-Kharkhi and M.E. Azhar

Abstract

Sugar-cane (Saccharum officinarum) juice with initial total soluble solids (TSS) of 15 °Brix was extracted from blanched sugar-cane stalks and was used for the production of a double strength (30 °Brix) sugar-cane juice using a freeze-concentration process. The freeze-concentrated juice was lower in yeast and mould count, pH and colour values, but higher in non-enzymic browning (NEB) index, chlorophyll content, total aerobic count and relative viscosity as compared to the fresh juice. A sensory evaluation performed on the samples indicated that fresh sugar-cane juice had higher hedonic scores in sweetness, flavour, aftertaste and overall acceptability as compared to that of freeze-concentrated juice (30 °Brix). The sensory scores of concentrated juice, however, improved upon reconstitution with mineral water. Reconstituted juice with TSS of 15 °Brix and 20 °Brix had the highest hedonic scores for the flavour, sweetness, aftertaste and overall acceptability attributes as compared to other reconstituted juice. During storage, the TSS and pH values of freeze-concentrated juice stored at 10 °C and 25 °C decreased considerably with storage times, and the decrease was more pronounced in the juice stored at 25 °C. The TSS and pH values, however, were unchanged at storage temperatures of –18 °C and 4 °C. The colour values and NEB index of all juice were not affected by the storage temperatures used.

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