Influence of process conditions on the mass transfer of osmotically dehydrated jambolan fruits

Abstract

Abstract Jambolan (Syzygium cumini) is a tropical fruit rich in anthocyanin pigments, but its fragile skin and pulp present low protection against physical damages and microorganisms. In this sense, a preservative technology, as osmotic dehydration (OD), was studied to investigate the impact of some variables over this process. At first, fruits of jambolan were submitted to physical and physical-chemical analysis. Furthermore, whole fruits underwent OD following a fractional factorial design. The influence of the process variables: temperature (20-50oC), sucrose concentration (30-60%), pressure (10-90 kPa), vacuum pulse time (5-15 min), calcium lactate concentration (0-4%) and number of vacuum pulse (1-3) was assessed on water loss (WL), solid gain (SG) and weight reduction (WR). In general, biometric analysis showed positive and significant correlation among the physical characteristics of jambolan. Physical-chemical assay demonstrated that the fresh fruit presents a potential source of bioactive compounds. The screening design showed that temperature, sucrose concentration, calcium lactate concentration and pressure affected the WL in jambolan. On the other hand, vacuum pulse time and number of vacuum pulse showed no influence on the WL, SG and WR; therefore, these variables must be fixed at the most economically viable level for any further trials.