Effect on Storage Life

Aliphatic groups which can fix the water molecules hy dispersion forces are no less disruptive. A minimum of free enthalpy will be attained when an ice-like water structure is arranged around a hydrophobic group (tetrahedral-four-coordination). Such ice-like hydration shells around aliphatic groups contribute, for example, to stabilization of a protein, helping the protein to acquire its most thermodynamically favorable conformation in water. 

The highly structured, three-dimensional hydrogen bonding state of ice and water is reflected in many of their unusual properties. 

Additional energy is required to break the structured state. This accounts for water having substantially higher melting and boiling points and heats of fusion and vaporization than methanol or dimethyl ether (cf. Table 0.3). Methanol has only one hydrogen donor site, while dimethyl ether has none but does have a hydrogen bond acceptor site neither is sufficient to form a structured network as found in water. 

Drying and/or storage at low temperatures are among the oldest methods for the preservation of food with high water contents. Modern food technology tries to optimize these methods. A product should be dried and/or frozen only long enough to ensure wholesome quality for a certain period of time. 

Naturally, drying and/or freezing must be optimized for each product individually. It is therefore necessary to know the effect of water on storage life before suitable conditions can be selected. 

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Sometimes technological advances create new problems. As we find more ways to extend the shelf of life of processed foods, we then confront new problems causing product acceptability loss. These new problems may provide opportunities for the application of enzymes, new and old, to food products. Indirect technological advances such as those in the packaging industry can often have an effect on storage life of products, such as improved oxygen or moisture barriers or substantially less expen-... 

OLiAS JM, SANZ LC, RIOS JJ and PEREZ AG. 1990. Characterization of methyl jasmonate effects on storage life and frait quality of apples. XXll Intern Horticultural Cong. Paper 3330. 

Nickerson, J. T. T., Goldblith, S. A., Masurovsky, E. R., Study of Effects of Substerilization Doses of Radiation on Storage Life Extension of Soft-Shelled Clams and Haddock Fillets, Annual Report for U. S. Atomic Energy Commission under Contracts AT(30-l)-2329, Task XII, and AT(30-1) (1962). 

Barbier, J.W., Hanhela, P.J., Huang, R.H. and Paul, D.B. (1990) Effect of temperature on storage life of polysulfide aircraft sealants. Polymer Testing, 9(5), 291-313. 

Maca, J.M., Miller, R.K., Bigner, M.E., Lucia, L.M., and Acuff, G.R. 1999. Sodium lactate and storage temperature effects on shelf-life of vacuum packed beef top round. Meat Science 53 23-29. 

The sea dumps created two major concerns. The first was that the weapons were being shipped from their storage depots by train to the loading docks. Fear of an accident along the way was paramount. Second, sea dumping and its effects on marine life were sources of environmental and commercial concern and protest. 

Of the numerous reasons for measuring and controlling the moisture content of dehydrated foods, one of the more important is the effect of moisture content on the stability of the food. The storage life of a food generally increases with decreasing amount of water and it is therefore customary to dehydrate the food to some safe moisture level which is determined empirically. 

If vitamins are added to a product to make a nutritional claim, it is critical that shelf-life studies are undertaken to prove that the overages added are sufficient to ensure that the label claims can be met at the end of product shelf life. This is important as none of the vitamins are fully stable in a soft drink environment and some, for instance vitamin C, are very quickly lost in the presence of oxygen. The addition of the fat-soluble vitamins to a soft drink also offers a formulation challenge to ensure that they are fully dispersed and that there are no problems with neck ringing during storage. Trace metals, particularly the transition elements, can also have a deleterious effect on vitamin shelf life, and sometimes metal scavengers, such as EDTA or phosphate salts, are added to improve the shelf life. 

Bissett, 0. W. Veldhuis, M. K. Rushing, N. B. Effect of heat treatment temperature on the storage life of Valencia orange concentrates. Food Tech., 1953, 7, 258-260. 

Adhesive. Urea-formaldehyde water-based dispersions are the most widely used particleboard binders. The low-cost, rapid curing, and colorless properties of urea-formaldehyde adhesives make them the adhesive of choice for most interior particleboard. These adhesives have been continuously improved by the resin manufacturers, resulting in reduced press times without detrimental effects on their storage life or handling characteristics. 

Thermo-mechanical analysis (TMA)26 and DMTA292 have been used to study the viscoelastic properties of bread, a composite two-phase system. The moisture dependence of Tg was similar to that of pure amorphous starch and gluten.242,282 293-295 At the moisture content of bread, water exerts its full plasticization effect on the composite polymer matrix, reducing the effective Tg to about -10° to - 12°C,26,292 well below normal shelf life storage temperatures of this product. 

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