The feasibility of date processing Phoenix dactylifera L. var Sufri components using physical and pectolytic enzyme treatments
The Sufri variety of date is widely cultivated in Saudi Arabia, where it 'produced large quantities of dates. The high quality dates are consumed fresh, dried or preserved, the surplus and second quality dates may be damaged by improper harvesting, handling, transporting and processing. The Sufri variety of date is one of moderate quality and there is a surplus in local markets for processing into overflows to be used as "a base" for the food industry. The present work was conducted to increase soluble solids, including sugars, in the overflows and to maintain the quality of the underflows; chemical analysis of both the overflows and the underflows revealed that Sufri date contains proteins/ amino acids and pectin in small quantities, which can be utilised as byproducts. Physical treatment involved maceration with different ratios (date/water) at mild temperatures (30-60°C) for different times (10- 30 min). Over this range the increase in soluble solids in the overflow was at a minimum but the underflow retained its quality and softening of date tissues was achieved. Different extraction ratios indicated that a lower ratio produced a low overflow which was turbid, but that the higher ratios produced overflows which were dilute. Serial extractions with the same ratio in the initial extraction was not practical. In enzymic treatment, pectolytic enzymes were incubated with date underflows at different concentrations, temperatures for various incubation times. Overflows increased significantly over a short time and at low temperatures (30 min and 30°C) indicating the effectiveness of pectolytic enzymes in releasing more of the overflows, and sugars were increased in the overflows as an indication of the effect of these enzymes on date cell walls. Pure pectolytic enzymes were investigated and it was found that specificity was very important for selection of suitable pectolytic enzymes. It is concluded that the Sufri variety of date is a good source of reducing sugars, and its by-products have a promising future.