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 properties 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.
