Lipases produced extracellularly by bacteria and fungi are being widely used in the food industry for flavour development. During tea processing, the possibility of enhancing the flavour of tea by the exogenous addition of lipase has not been reported. It was therefore considered worthwhile to amend tea leaves with microbial lipases and observe the changes in the flavour profile of the finished product. Among a few fungal lipases screened, the enzyme secreted by Rhizomucor miehei increased the formation of desired flavour compounds. Hence, studies were initiated to achieve enhanced production of this industrially useful enzyme. Under solid-state fermentation R.M. miehei produces an extracellular lipase in copious amounts on a simple solid substrate within 96 h, which is active at lower temperatures and at near-neutral pH. These attributes make this enzyme suitable for use during the manufacturing of tea, where reactions are carried out at temperatures of 15 to 20˚C and pH range of 5 to 7. In the present study, exogenous addition of lipase resulted in an increase in flavour volatiles, which contribute to the aroma of tea.Keywords: lipase for tea processing, lipase for aroma enhancement, Rhizomucor miehei, extracellular lipase, solid-state fermentationIn recent years research on microbial lipase production has been intensified due to the potential use of the enzyme to hydrolyse fats and synthesis of specific esters with desirable flavour properties. Modification of the existing enzymes to yield forms that can be used under conditions that are harsher than the present or that have altered activities or substrate specificity is a vital aspect that is gaining ground. Such manipulations are feasible with lipases since they can be obtained in large amounts from industrial fermentors (Torossion & Bell, 1991) and display a host of substrate selectivities.Industrial enzymes have been increasingly used for an expanding variety of processes over the last few decades. Enzymes like proteases, lipases and amylases are currently widely used in detergents and the food technology industry. The hydrolysis of water-soluble carboxylic acid esters by many lipases is slow and the catalytic ability varies. The substrate specificity of lipases is often crucial to their applications for analytical and industrial purposes. While enzymes with a broad substrate range are suitable for certain applications, those lipases that are very selective in their substrate requirement are preferred for catalyzing certain other reactions. Microbial lipases are synthesized both intracellularly and extracellularly and their relative proportion is influenced by the culture conditions. Fungi are a valuable source of lipase as these organisms produce the enzyme extracellularly. Solid-state fermentation (SSF) where productivity is high offers a better alternative to submerged fermentation. In addition, the amount of lipase produced is dependent on several environmental factors such as cultivation temperature, pH, nitrogen and carbon sources, concentration of...

The implications of the dietary habit of Helicouerpa armigera on the virulence and infectivity of its nuclear polyhedrosis virus were examined in the laboratory by conducting three bioassays involving six different food regimes. Irrespective of the combination of food rations a significantly lower percentage mortality and higher time taken to kill the larvae were observed in cotton-fed and dosed larval groups over the others. Correlation and regression analysis was also found to be significant between biochemical factors and percentage mortality. A negative correlation between percentage mortality and biochemical factors like foliar pH, phenols, tannins and protein binding capacity and positive correlations between percentage mortality and gut passage time were observed.

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