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Wheat treated with mint and eucalyptus leaves powder was stored for six months in four different storage structures viz., jute bags, peru (made from bamboo strips), metal bins and polythene bags. Samples were analysed at monthly intervals for physico-chemical characteristics. After six months of storage, per cent damage increased, whereas weight and density decreased in untreated wheat, but no significant (P < 0.05) changes were observed in treated grains. Proximate principles increased significantly (P < 0.05) in untreated grains except crude fat which decreased, but no significant changes were observed in their treated counterparts. Mint leaves powder was able to protect wheat stored in different storage structures for 6 months, whereas eucalyptus leaves had their protective effects only for 5 months.

Dependency of the antimicrobial activity on the conformation of lysozme was examined by the means of gradual thermal inactivation at neutral pH and different temperatures. We found that heating of lysozyme at increasing temperatures for 20 min in pH 6.0 results in progressive loss of enzyme activity, while greatly promotes its antimicrobial action to the Gram-negative bacteria without a detrimental effect on the inherent bactericidal activity to Gram-positive ones, suggesting action independent of catalytic function. The most potent bactericidal conformation of lysozyme to either Gram-negative or -positie bacteria was that retaining approximately 50% of the native enzyme activity (HL80/6). HL80/6 showed several fold increase in surface hydrophobicity, with exposed two thiol groups, and 17% deamidation. Spectrophotometric analysis of HL80/6 revealed slight changes in its secondary structures, but considerable global conformational changes as a result of the formation of beta conformation, via cyclic imide, at the three aspartylglycyl sequences of lysozyme molecule. Direct damage to the bacertial membranes by HL80/6, was demonstrated by using ELISA and liposomal membrane model. Furthermore, the antimicrobial activity of HL80/6 was inhibited by the divalent cations Ca2+ and Mg2+ suggesting that HL80/6 interacts at a divalent cation binding site on the bacterial membrane and subsequently permeabilize it. The results introduce an interesting structure-antimicrobial relationship that the antimicrobial action of lysozyme is independent of its catalytic function. In addition, it is worth emphasizing that the naturally-occurring conformational transition of lysozyme at physiological temperatures can be a biologically relevant event to switch its antimicrobial specificity to include the food-borne pathogens and heralding fascinating opportunities for application in formulated food systems.

Physico-chemical protein modification involved in food processing is used for "engineering" the structure-property relationship of foods. The three main tools used for protein modification are food formulation, mechanical and thermal (heating/cooling) treatments. They correspond to the main stages of all food technologies. Food structural design is based upon incompatibility and complexing of food biopolymers as well as upon fundamental features of physico-chemical properties of biphasic aqueous systems. Some examples of functional biopolymer modification are considered in systems such as meat extenders, fat replacers, ice cream mixes and wheat flour doughs.

Sodium caseinate is an effective substrate for transglutaminase. Crosslinking takes place at fast reaction rates resulting in high degrees of crosslinking. The polymers can be hydrolysed by trypsin, but the proteolysates contain residual portions of non- or partlyhydrolysed aggregates. Crosslinking of hydrolysed sodium caseinate decreased the number of free amino groups, but leads only to a very small increase in molecular weight of the peptides.