Production of High Quality Dehydrated Food Products by Simple Technique for Small Projects

Abstract

he objective of this study was to dry onion and potato with a simple technique for small projects. Both of onion and potato slices submerged in yeast (Saccharomyces cerevisiae) suspension for 2, 4 and 6 hours as a pretreatment and then, the samples were preheated in air ventilation oven at 120ºC for 15 mins. All samples were dried under sunlight until reached to final moisture content 9-10%. The aims of the thermal treatment (at 120ºC for 15 mins.) were sterilized, inhibition the yeast and enzymatic browning, beside, decrease the moisture content, sundried time and partial gelatinization of potato starch. The physiochemical characteristics, microbiological count and Sensory evaluation for both onions and potatoes were estimated. The results showed that, the increasing of fermentation periods led to increase the growth rate of yeast while, the pH value, total soluble solids and color index decreased. Also, the results explained that, decreased of phenol compounds, flavonoids and antioxidant activity by increasing the time of fermentation process and pungency (as pyruvic acid) for dried onion. Meanwhile, no significant difference observed in rehydration characteristics of both treated, dried onion and potato samples by increasing the time of the fermentation process. Finally the results showed that, the Samples submerged in yeast suspension for four hours, preheated at 120 ºC for 15 min. and drying under direct sunlight had high nutritional value and good quality.