Water microbiological growth

Chirife, J. and Buera, M.P. 1995. A critical review of the effect of some nonequilibrium situations and glass transitions on water activity values of foods in the microbiological growth range. J. Food Engin. 25, 531-552. 

Chirife, J. and Buera, M.B. 1996. Water activity, water glass dynamics, and the control of microbiological growth in foods. Crit. Rev. Food Sci. Nutr. 36, 465-513. 

Chlorine is the oldest and most widespread method of water disinfection. In reverse osmosis systems, chlorine may be added to feedwater for control of micro-organisms and, in addition, to prevent membrane fouling by microbiological growth. According to Vos et al. [i,2], chlorine will attack cellulose diacetate membranes at concentrations above 50 ppm. Membranes were found to show a sharp increase in salt permeability and a decrease in strength after one week of continuous exposure. Under milder conditions (10 ppm chlorine for 15 days) no detectable change in performance was observed. Spatz and Friedlander [3] have also found cellulose acetate membranes to be resistant to chlorine when exposed to 1.5 ppm for three weeks. 

Treat immediately with a water-soluble biocide. Continue treatment weekly to prevent further microbiological growth. 

Water quality is usually defined in terms of chemical and bacteriological purity, particulate matter content, and endotoxin levels. Potable water is normally from the municipal water system, which may have been treated with chlorine to control microbiological growth. Soft water and deionized water have undergone ion exchange or similar treatment to eliminate unwanted ionic species, such as Mg2+ and/or Ca2+. Purified water, water for injection, and other types of water meeting compendial specifications are produced by ion exchange, reverse osmosis, distillation, or a combination of such treatments. 

Figure 1-23 Relationship Between Water Activity aw) and Glass Transition Temperature (Tg) of Some Plant Materials and Biopolymers. Source Reprinted with permission from J. Cherife and M. del Pinar Buera, Water Activity, Water Glass Dynamics and the Control of Microbiological Growth in Foods, Critical Review Food Sci. Nutr., Vol. 36, No. 5, p. 490, 1996. Copyright CRC Press, Boca Raton, Florida.

Another factor tha( affects microbiological growth aud transmission is the relative humidity of (he environment, which is a measure of the water content of the air. High humidity in cold rooms should be avoided since condensation that forms on the walls and ceiling creates the proper environment for mold growth and buildups. The drip of contaminated condensate onto food products in the room poses a potential health hazard. 

Use Controlling and eliminating microbiological growth in pulp- and paper-mill water systems as well as for antibacterial papers. 

Syrup or glass, [ajg +12.9 (c = 4.5 in water). Microbiological activity 20,000 LBF units/mg. An LBF unit is that amount of the growth factor contained in one mg of Basamine-Busch, a standard yeast extract manuf by Anheuser-Busch, Inc. 

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