Effect of processing of dates into date juice concentrate and appraisal of its quality characteristics

Date palm (Phoenix dactylifera) is widely
cultivated in Kutch district of Gujarat and the fruits are
harvested at immature stage before the onset of monsoon
to prevent spoilage. The immature date fruits with less
commercial value were used for processing into date juice
concentrate. Immature dates were crushed and treated with
0.1% pectinase enzyme for 120 min to obtain maximum
juice. Date juice was found to be rich in reducing sugars
(16.1%) and total sugars (18.3%). Juice was pasteurized
at 85°C to inactivate the enzyme, cooled and centrifuged
at 3000 rpm to get clear juice. The juice was concentrated
in a thin fi lm evaporator to a total soluble solids (TSS) of
76°Brix in 2 passes. Chemical composition of date juice
during different stages of concentration was determined.
Date juice concentrate was packed in low density polyethylene
bags of size (22 cm × 14 cm) and frozen in blast
freezer at –40°C and stored at –20°C. Storage of date juice
concentrate at –20°C for 6 months indicated no signifi cant
changes in TSS, acidity, ascorbic acid, total sugars and pH.
Hunter colour lightness L, and redness a values of date juice
concentrate decreased whereas b values increased during
storage. Date juice concentrate was stable during 6 months
storage could be reconstituted for preparing ready-to-serve
beverages with acceptable sensory quality.