Clarification of pectin-containing juice using ultrafiltration.

摘要

Membrane-based processes are emerging as significant unit operations for clarification of fruit juice in the food industry. In this article, pretreatment of pectin-rich juice, its clarification using ultrafiltration and storage study of the filtered juice are discussed. Mosambi (Citrus sinensis (L.) Osbeck) juice is considered as a case study. Optimum conditions for enzymatic treatment for depectinization are reported. Efficacy of enzymatic treatment is explored compared to other pretreatment methods. Selection of a suitable membrane, performance of clarification, quantification of flux decline and methods to improve the permeate flux are also discussed. Finally, the effects of various parameters on the shelf-life of the clarified juice are presented. After depectinization, the leftover pectin present in the juice causes flux decline during ultrafiltration. Higher pore-sized membranes may not lead to higher permeate flux during ultrafiltration because the filtration is mainly gel layer-controlled. Apart from conventional methods for membrane cleaning like backflusing, application of external electric field may improve the ultrafiltration flux due to the charged nature of pectin at its natural pH. Clarified juice has adequate shelf-life without addition of any external preservative or heat treatment.