Role of Water Activity in Food Preservation

Abstract

AbstractWater activity is one of the main factors in limiting the growth of microbial cells and regulating the level of spoilage in foods. Water activity has been proven to be a principal factor accountable for safeguarding of food matrix, stabilization of the food supply, budding diverse kinds of shelf-stable products, food stability, modulating microbial response, and assessing the species of microbes confronted in food. Brined products; semi-dry foods, fermented food stuffs, poultry, eggs, cereals, milk, bakery, fruits, vegetables, confectionary, jellies, chocolates, jams, and concentrated condensed milk are instances of food preservation by lowering water activity values. Use of heat, natural drying, forced drying, freezing, crystallization, and osmotic concentrations are the basic techniques applied to decrease water activity of foods. Food matrix that are subjected to heat treatments or low-moisture foods does not hold greater than 25% moisture (water activity less than 0.60). A further class of shelf-stable food that holds 25–50% moisture is termed as intermediate-moisture foods (water activity ranges between 0.60 and 0.85). Lastly, food that contains greater than 50% moisture is termed as high-moisture foods (water activity ranges between 0.85 and 1.00). Diminution of water activity in food products restricts the development of vegetative cells, spore germination, toxin generation by microbial cells, and enzyme activity. This chapter illustrates particulars that endeavor to elucidate why the idea of water activity has been effectively used to attain microbial safeguarding of food products, its mechanism of action and its function in food preservation for microbial development and metabolic action.