Production of spray-dried “terung asam” (Solanum lasiocarpum dunal) powder

Abstract

Easily perishable and highly seasonal “Terung Asam” (Solanum lasiocarpum Dunal) fruit, a geographical indication plant of Sarawak, was converted into powder for shelf life extension. Spray drying was employed with a range of inlet temperature (140-180 °C) and the slurry was cooperated with food graded maltodextrin (5-25 % w/w) as food processing aid. The spray-dried “Terung Asam” powders were analysed for process yield, moisture content (Mc), water activity (Aw), hygroscopicity (Hg), water solubility index (WSI), bulk density and colour. The reconstituted powders were assessed by determining total soluble solid (TSS), pH, viscosity and colour. The results indicated that the increase in inlet temperature had resulted in reduction in Mc, Aw, and Hg. In addition, higher concentration of maltodextrin led to reduction in Mc and Hg. At the spray drying inlet temperature of 160 °C and feed added with 25 % w/w maltodextrin, “Terung Asam” powder with the following optimal physicochemical properties was produced: Mc, 2.95±0.42 %; Aw, 0.11±0.02; Hg, 17.76±0.28 %; WSI, 98.89±1.37 %; and wettability, 621.60±119.03 s. The optimized reconstituted powder had lower L*, a* and b* values than the fresh juice, indicating it is lighter in colour, less reddish and less yellowish. Overall, the production of “Terung Asam” using spray drying is feasible with the addition of food processing aid.