Processing technology for concentrated plum products for economical marketing and prolonged shelf life

摘要

The processing technology developed for the preparation of plum juice and concentrates has highlighted the future potentials for commercial utilization of the highly perishable fruit during the glut season for off-season use. Superior quality concentrates were obtained from Santa-Rosa variety of plum. Under refrigerated storage, the products retained high quality of colour and flavour better than under high summer temperature. Processing of plum into juice concentrates has practical implications for commercial production, though, commercial level trial aimed at bulk production for test marketing, consumer acceptability of reconstituted products, seems necessary. In the present pilot-scale investigation, yields of the pulp from the two plum cultivars, Santa-Rosa and Satsuma obtained from Chogal, Kashmir, and Alubukhara from the orchards of Punjab Agricultural University, Ludhiana, were 75, 66.9 and 69 per cent, respectively. Cold extracted pulp concentrate, although poor in colour, yet, possessed richer flavour than hot extracted pulp. The juice yield was increased by hot break and use of pectinolytic enzyme. Santa-Rosa pulp gave maximum (89%) juice recovery. During 24 weeks of storage at ambient (15-40℃) and low (0-4℃) temperature, TSS, sugars, acidity and pH remained almost constant while pectin decreased somewhat in stored products at room temperature. Reducing sugars also increased. The red colour of concentrate declined considerably under ambient storage. There was browning in concentrates as shown by increased yellow Tintometric units of reconstituted samples.Sensory evaluation of RTS-drinks prepared from stored concentrates confirmed the superiority of hot break process.