Impact of Thermal and Membrane Processing on the Biochemical Quality of Pretreated Pomegranate and Pineapple Juices

Abstract

Pomegranate (Punica granatum L., Punicaceae) and pineapple (Ananas comosus L., Merril) are among the most widely consumed tropical non-citrus fruits, owing to their pleasant aroma, refreshing taste, and desirable °Brix to acid balance. Their juices are commonly utilized in fruit-based beverages either as single-fruit products or in blends with other fruit juices. The present study focused on evaluating the physicochemical characteristics of pomegranate and pineapple juices processed through thermal and membrane techniques during storage. Juices from both fruits were subjected to pretreatment using egg albumin, and it was observed that a concentration of 2 g/L was most effective in removing colloidal matter. Storage studies conducted on the clarified and pretreated juices, involving biochemical analyses, indicated that for pomegranate juice, superior quality retention was observed in treatments ranked as follows: thermal processing with preservative addition; membrane filtration using 0.1 µm at 15 psi (1.0342 bar) and 30 Lph followed by thermal treatment; 70 kDa at 15 psi (1.0342 bar) and 30 Lph with thermal treatment; 44 kDa at 15 psi (1.0342 bar) and 40 Lph with thermal treatment; 10 kDa at 15 psi (1.0342 bar) and 40 Lph with thermal treatment; and thermal processing combined with 44 kDa filtration at 15 psi (1.0342 bar), 40 Lph and preservative addition. In the case of pineapple juice, the treatments showing better quality preservation were ranked as: thermal treatment with added preservative; membrane processing using 70 kDa at 15 psi (1.0342 bar), 30 Lph followed by thermal treatment; 44 kDa at 15 psi (1.0342 bar), 40 Lph with thermal treatment; thermal treatment combined with 44 kDa filtration at 15 psi (1.0342 bar), 40 Lph and preservative addition; and 70 kDa filtration at 15 psi (1.0342 bar), 30 Lph with preservative addition. During a storage period of 180 days, biochemical evaluation of pomegranate juice showed values of 9.914% for total soluble solids, 5.659 for colour intensity, 3.121 for browning index, 0.478% for turbidity, 0.695% for titratable acidity, pH of 4.68, and viscosity of 2.12 cP. Similarly, pineapple juice recorded total soluble solids of 12.782%, colour intensity of 5.562, browning index of 5.27, turbidity of 0.702%, titratable acidity of 0.769%, pH of 4.79, and viscosity of 3.098 cP during the same storage duration.