Effect of fluidized bed drying on properties of dehydrated apples

Abstract

SummaryThree sorts of apple (Idared, Golden Delicious and Jonathan) were dried in a laboratory-type fluidized bed dryer. Apples were cleaned, cored, peeled and cut into 10 x 10 x 10 mm cubes or into slices 5 x 3 mm thick and 40 mm long. A part of the samples was dipped for 3 min prior to drying in 0.1 % ascorbic acid solution. Drying temperature was 80 "C. Some physicochemical and sensory properties of fresh and dried apples were determined. Moisture content in dried samples varied between 9 and 12%. Greater quantity of water results in lower sensory characteristics. The sensory characteristics of apples were determined by a scoring system with weighed factors in a 20-point scale. Glucose, fructose, saccharose, citric acid, malic acid and ascorbic acid levels were analysed by enzymatic methods. Contents of glucose, fructose and saccharose in dried apples were substantially unchanged compared to fresh apples. The drying process had the most influence on contents of citric and malic acids. Higher rehydration ratios were measured in spaghetti-like sclices and in ascorbic acid treated samples. ldared had the best characteristics with regard to physicochemical and sensory results.

Rehydration ratio of fluid bed-dried vegetables

“…Dried vegetables are used in all sorts of industrial food products, especially in instant foods (Vrac & Gruner 1994;Garcia-Reverter et al 1994;Swasdisev & Soponronnarit 1999), which have a very short preparation time (between 5 and 15 minutes). Therefore, it is very important that dried products have short rehydration times and retain the characteristics of fresh vegetables (size of samples, colour, taste, odour etc.).…”

Time and speed of fruit drying on batch fluid-beds

“…Rehydration characteristics were used as a quality index of the dried product (Vrac & Gruner 1994). Approximately 3 g (±0•01 g) of dried samples were placed in a 250 ml laboratory glass (2 sets for each sample) and 150 ml distilled water was added, the glass was then covered and heated to boiling point within 3 minutes.…”