Fruit puff-drying

The foam drying process is limited to specific products, such as fruit powders, for preparation of instant drinks. Techniques like vacuum puff drying, foam mat drying, microflake dehydration, and foam spray drying have been described elsewhere in this book. Among these, the foam mat drying process has received considerable attention. 

Moy and Speilmann (90) recently reported on the economic feasibility of vacuum puff freeze drying of tropical fruit juices and nectars. They considered the process economically feasible if production rates were 250,000 or 1,000,000kg of dried nectar base per year (two plant sizes) with an assumed level of 35% sucrose (wet weight basis) blended with the juice or puree before dehydration. One assumption made in their study was that a marketing share equivalent to 0.5% of the annual orange juice volume in the U.S. was attainable. 

The white fruit bodies of the North American puff ball Calvatia rubro-flava turn golden yellow when the toadstools are touched or dried. The dried fruit bodies contain a unique group of benzoquinone semicarbazone pigments 250). These compounds may be isolated from the fungus by extraction with methanol and % have been purified by column chromatography on Sephadex LH-20 followed by preparative thin layer chromatography on silica gel. 

Moy, J. H., 1971. Vacuiun-puff freeze drying of tropical fruit juices. /. Food Sci. 36 906-910. 

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