hanged if a fan is mountedCooling coil The cooli B4DV-20-C Bevel-helical speed reduction gearboxes B4

Flender/Flender Gear Units/Bevel-helical speed reduction gearboxes B4

um-, or low-hygroscopicity solids). Table 3 lists the measured minimum awvalues for microbial growth or spore germi- nation. If awis reduced below these values by dehydration or by adding water-binding agents, such as sugars, glycerol, or salt, microbial growth is inhibited. Such additivesshould not affect the avor, taste, or other quality criteria, however. As the amounts of soluble additives needed to depress weven by 0.1 are quite large, dehydration becomes particularly attractive for high-moisture foods as way to reduce aw. Figure 5 shows schematically the water activity versus moisture content curve for different types of food.Rockland and Beuchat ( provide an extensive compilation of results on water activityand its applications. Figure 6 shows the general nature of the deterioration reaction rates as function ofa wfor food systems. Aside from microbial damage, which typically occurs for aw/H1 0.7, oxidation, nonenzymatic browning (Maillard reactions), and enzymatic reactions canoccur even at very low wlevels during drying. Laboratory or pilot testing is essential to ascertain than no damage occurs in the selected drying process, for this cannot, in general,be predicted. 1 Mujumdar and Beke Table 3 Minimum Water Activity awfor Microbial Growth and Spore Germination Microorganism Water activity Pseudomonas ,Bacillus cereus spores 0.9 . subtilis ,. botulinum spores 0.9 . botulinum ,Salmonella 0.9 Most bacteria 0.9Most yeast 0.8Aspergillus niger 0.8 Most molds 0.8 Halophilic bacteria 0.7 Xerophilic fungi 0.6 Osmophilic yeast 0.6 Source : Brockmann, 1. 1.1.4 Equilibrium Moisture Content for Grains Numerous theoretical, semiempirical and empirical models have been proposed in the literature to the equilibrium moisture content isotherms for grains. The theoretical mod-els are based on capillary condensation or adsorption (Brunaner, Emmett, Teller [BET],Guggenheim, Anderson, de Boer, [GAB]). Henderson and Chung proposed purely em-pirical model to measured da