Kadam, Patil, Kaushik - Foam Mat Drying
lon-coated fiberglass belt, on perforated stainless steel trays, and on an endless stainless
steel belt. Lemon powders are presently being produced by a commercial concern on a
perforated tray or "crater" type dryer, and a number of fruit and vegetable products are
produced on an endless stainless steel belt dryer which uses high belt speed and very
short drying time. Over the years, foam-mat drying has been applied to many fruits in-
cluding tomato paste mango, soymilk, star fruit, cowpea and bananas Pineapple, Lemon,
Citrus (Kinnow), Sapota, apple etc.
Addition of soy protein in a solid form at the 10 g/100 g level is very effective foam
inducer, foam mat drying of banana to produce free flowing powder reducing the densi-
ty of the banana puree to 0.5 g/ml after 12 min of whipping. The drying behaviour of the
banana foam mat is strongly affects the physical characteristics of the foam, i.e. the den-
sity and thickness, while increasing the air temperature markedly reduced the drying
time, even at 75°C and 90°C. Neither the air flow conditions nor the sugar content of the
foam mats as obtained through osmotic pre-treatment had a profound effect on drying,
although forced convection conditions were better than drying by natural convention.
The drying of foamed syrups of different fruits like orange, lemon, grapefruit, toma-
toes, strawberry, guava and apple were carried out in a solar energy augmented drying
unit.. The results showed that foaming decreased the time of drying by 30.8–41.5% in
the case of direct sun drying and by 47.1–73.2% in the case of solar drying compared to
the drying time of unfoamed syrup. So it was concluded that solar-augmented foam-mat
drying technique proves to be of sufficient efficiency and acceptability to replace spray
drying which is a highly complicated and energy-consuming technique.
REFERENCES
Akintoye, O. A. and Oguntunde, A. O. (1991). Preliminary investigation on the effect of foam
stabilizers on the physical characteristics and reconstitution properties of foam-mat dried
soymilk. Drying Technology, 9(1), 245-262.
Anjaria, B.V. and Chivate, M.R. (1966). Studies in foam-mat drying. Indian Chemical Engi-
neer, Transactions, 8(3), 64-68.
Bates, R.P. (1964). Factors affecting foam production and stabilization of tropical fruit
products. Food Technology, 18(1), 93-96.
Beristain, C. I., Garica, H.S. and Vazquez, A. (1993). Foam-mat dehydration of Jamaica) hi-
biscus sabdariffa L.) Instant drink. Drying Technology, 11(1), 221-228.
Berry, R.E., Bissett, O. W., Wanger, C. J., Jr., and Veldhuis, M. K. (1965a). Foam-mat dried
grape fruit juice. Time-temperature drying studies. Food Technology, 19(3), 126-128.
Berry, R. E., Wanger, C.J., Jr., Bissett, O. W. and Veldhuis, M. K. (1972). Preparation of instant
orange juice by foam-mat drying. Journal of food Science, 37(4), 803-808.