Water Activity and Moisture Content of Selected Foods of Commerce in Hawaii

Abstract

Refrigeration and the use of certain food additives were studied as optional means of influencing the water activity (aw) of a selection of ethnic foods in Hawaiian commerce. The aw was measured at 27.6 and 6.7°C. The former temperature did not result in any of the aw <0.97, a value conducive to spoilage and the growth of Clostridium botulinum, whereas the latter temperature did not result in aw >0.89, a value more in the vicinity of a biologically safe food environment. The foodstuff (Manapua) with the lowest gravimetric moisture content (35.9%) gave among the highest aw (0.88) at the lower temperature, thereby showing no relationship, necessarily, between total moisture content and aw. The lower temperature was recommended as the storage and holding temperature for the ethnic foods in the tropical environment. The additives (acetic, propionic and butyric acids, glycerol, propyleneglycol, potato starch, and Guar gum) did not have any appreciable impact on aw (at 26.7°C).