Effects of Water Activity (a_w) on Microbial Stability: As a Hurdle in Food Preservation

Physical and flow properties of rice protein powders

“…From a physicochemical point of view, a w is defined as the ratio of vapor pressure of water in a food and the vapor pressure of pure water at the same temperature. The a w describes the extent to which water present in a food is bound, and therefore its availability to participate in certain reactions (Labuza, 1975), having a major influence on microbial, chemical and physical stability of food (Bell, 2007;Roudaut, 2007;Tapia et al, 2007).…”

“…products with a w < 0.6 (Tapia et al, 2007). From a physicochemical point of view, a w is defined as the ratio of vapor pressure of water in a food and the vapor pressure of pure water at the same temperature.…”

Water activity of poultry litter: Relationship to moisture content during a grow-out

“…Fontana (2007) and Taoukis and Richardson (2007) (Tapia et al, 2007). It has previously been recommended that the A w of poultry litter should be kept below 0.84e0.91 to restrict the growth of Salmonella and other microbiota (Chinivasagam et al, 2012;Eriksson De Rezende et al, 2001;Hayes et al, 2000;Payne et al, 2007).…”

Comparative study of deteriorative changes in the ageing of milk powder

“…They have a tendency to sorb moisture and form caked powders that are not free flowing. The increase in moisture content, due to the elevated water activity, causes bridge formation between particles, protein denaturation and modification (Haque et al, 2010;Liu and Chaudhary, 2011), the progress of Maillard reactions and decolouration (Bell, 2008), bacteria growth (Tapia et al, 2008) and quality loss (Sablani et al, 2007). These deteriorative changes start by sorbing moisture form environment, leading to a decrease in the glasstransition temperature of amorphous components to below ambient conditions, which initiates crystallisation and an increase in the stickiness of the powders.…”