Author:

Abstract

Dehydration of guava juice into powdered particles gives a considerable reduction in volume and is an effective method of prolonging the shelf life. Therefore, a research study was conducted to determine the effect of different drying methods and the addition of drying aids on the physico-chemical proper-ties and sensory characteristics of dehydrated guava concentrate. Instant guava-drink-powder samples were obtained by dehydrating the concentrated guava juice using freeze drying, spray drying and tunnel drying techniques. Guava juice at 10.5°Brix was used to prepare the fruit powders. A significant reduction (p<0.05) in titratable acidity of 0.22% as citric acid and an increase in pH of 0.44 after drying of guava juice indicated that some acids were lost during the drying process. The oxidative loss of ascorbic acid was considerably lower in freeze drying (18.8%) compared to tunnel drying (32.2%). Spray dried powders were obtained from the guava juice with different maltodextrin concentrations as drying aids. When 30% maltodextrin was added to guava juice, the solubility of powder was 95% whereas, adding 60% maltodextrin decreased the solubility to 86%. The chromametric parameters L* (lightness), a* (redness) and b* (yellowness) were found to be significantly (p<0.05) affected by drying methods. Twenty trained sensory panellists ranked the juice prepared from the freeze dried powder as the highest and there were no significant differences (p>0.05) between the juice prepared from spray drying of guava juice upto 50% added maltodextrin. The freeze dried product had superior nutritional and sensory qualities, however spray dried product was stable and more economical to produce free-flowing guava powder with good stability.

Key words: Freeze drying; guava-drink-powder; maltodextrin; spray drying

DOI: http://dx.doi.org/10.4038/tare.v13i2.3138

Tropical Agricultural Research and Extension 13(2) 2010 pp.48-54

Keywords: Freeze drying, guava-drink-powder, maltodextrin, spray drying