Fermented soy sauce was dehydrated by spray drying to form powder, and moisture sorption properties of powdered soy sauce with or without cover of the flexible films were examined on different relative humidity by using saturated salt solutions at 30℃. The results obtained were summarized as follows:
The equilibrium moisture content of spray-dried soy sauce containing 18.3% moisture was determined to 52% by graphical interpolation method, and E.M.C. of powdered soy sauce covered with plastic films decreased at low relative humidity whereas sharply increased curves were seen at high relative humidity.
The rate constant of moisture adsortion K for the power covered with films were 66.2×10^(-5) to 225×10^(-5)/hr., and K´ became greater when film having higher water vapo transmission rate was used.
The shelf-life of powdered soy sauce covered with Al. foil/P.E. film by Brown formula at the accelerated condition of 38℃, 92% R. H. was the longest period, 164 days compared with any other films used, and the shortest period, 18 days in P.V.C. film.
|