Viruthagiri Thangavelu

Lipase catalyzed ester synthesis for food processing industries

Lipases are one of the most important industrial biocatalyst which catalyzes the hydrolysis of lipids. It can also reverse the reaction at minimum water activity. Because of this pliable nature, it is widely exploited to catalyze the diverse bioconversion reactions, such as hydrolysis, esterification, interesterification, alcoholysis, acidolysis and aminolysis. The property to synthesize the esters from the fatty acids and glycerol promotes its use in various ester synthesis. The esters synthesized by lipase finds applications in numerous fields such as biodiesel production, resolution of the recemic drugs, fat and lipid modification, flavour synthesis, synthesis of enantiopure pharmaceuticals and nutraceuticals. It plays a crucial role in the food processing industries since the process is unaffected by the unwanted side products. Lipase modifications such as the surfactant coating, molecular imprinting to suit for the non-aqueous ester synthesis have also been reported. This review deals with lipase catalyzed ester synthesis, esterification strategies, optimum conditions and their applications in food processing industries.

Evaluation of medium components by Plackett-Burman statistical design for lipase production by Candida rugosa and kinetic modeling.

Lipase production by Candida rugosa was carried out in submerged fermentation. Plackett-Burman statistical experimental design was applied to evaluate the fermentation medium components. The effect of twelve medium components was studied in sixteen experimental trials. Glucose, olive oil, peptone and FeCl3.6H2O were found to have more significance on lipase production by Candida rugosa. Maximum lipase activity of 3.8 u mL(-1) was obtained at 50 h of fermentation period. The fermentation was carried out at optimized temperature of 30 degrees C, initial pH of 6.8 and shaking speed of 120 r/min. Unstructured kinetic models were used to simulate the experimental data. Logistic model, Luedeking-Piret model and modified Luedeking-Piret model were found suitable to efficiently predict the cell mass, lipase production and glucose consumption respectively with high determination coefficient(R2). From the estimated values of the Luedeking-Piret kinetic model parameters, alpha and beta, it was found that the lipase production by Candida rugosa is growth associated.

Application of Central Composite Design and Artificial Neural Network for the Optimization of Fermentation Conditions for Lipase Production by Rhizopus arrhizus MTCC 2233

The response surface optimization strategy was used to enhance the lipase production by Rhizopus arrhizus MTCC 2233 in submerged fermentation. Various vegetable oils were experimented as an inducer using the optimized medium to study the influence on lipase production, and corn oil was found to be the best inducer for lipase production by Rhizopus arrhizus. The optimization of fermentation conditions, temperature, initial pH and agitation speed was carried out using corn oil as the inducer. Statistical analysis of the experimental data showed that the temperature, agitation speed, quadratic effects of temperature, initial pH and agitation speed and interactive effects of temperature and agitation speed are significant parameters that affect lipase production. The optimum fermentation conditions were achieved at 32°C; pH 6.0 and agitation speed of 107 rpm with the maximum lipase activity of 4.32 U/mL. Artificial neural network model was used to predict the lipase activity and cell mass production under various fermentation conditions. Unstructured kinetic models, Logistic model, Luedeking-Piret model and modified Luedeking-Piret model were used to describe the cell biomass, lipase production and glucose utilization kinetics respectively.

Medium optimization and in vitro antioxidant activity of exopolysaccharide produced by Bacillus subtilis

The present study involves medium formulation using an agro waste, cane molasses, as the carbon substrate that was used instead of sucrose, to produce exopolysaccharide from Bacillus subtilis. Plackett Burman design was applied to evaluate twenty selected components, from which cane molasses, yeast extract, CaCl2, NaCl were found to be significant for fermentation. To study the concentration of each component, response surface methodology experimental design was performed using central composite design. The response plots resulted in optimized conditions—Cane molasses-2.36%, Yeast extract-0.56%, NaCl–0.71%, CaCl2 — 0.05%—which yielded 4.92 g/L at 48 h, at a temperature of 37 °C, initial pH 7 under still conditions. Antioxidant activity of EPS on DPPH resulted in a reducing capacity of 61.19%, at a concentration of 0.8mg/ml, greater than standard, Vitamin C. The biopolymer could thus be an ecofriendly product which can be subjected to various industrial and pharmaceutical applications.

Statistical optimisation of methanolysis of jatropha oil using immobilised R. oryzae cells in n‐hexane system

The ability of immobilised whole cells of R. oryzae cells to catalyse the alcoholysis of jatropha oil with methanol in n‐hexane system was investigated. Response surface methodology using central composite design was used to study the effects of important parameters: reaction time, reaction temperature, catalyst concentration, molar ratio of alcohol to oil and water content in five levels on percentage yield of biodiesel. The linear effects of reaction time and catalyst concentration and the quadratic effects of catalyst concentration and molar ratio of alcohol to oil were found to be the significant parameters. The optimum conditions for biodiesel production were found to be: reaction time, 77.25 h; reaction temperature, 40.18°C; catalyst concentration, 3.70 w/v; molar ratio of alcohol to oil, 1:2.88 and water content, 11.20% (w/w of oil). The predicted yield of biodiesel was 79.87% (w/w) and the experimental yield at the optimised condition was 80.5% (w/w). This confirmed the validity of the proposed model.

Production of Tannase using Aspergillus niger by Submerged Fermentation

A study on optimization of submerged fermentative production of tannase by Aspergillus niger was carried out. Aspergillus niger (MTCC 3557) was used for maximum production of Tannase enzyme and the factors affecting the production were optimized. The optimum conditions for maximum tannase enzyme production in the Submerged Fermentation (SmF) using Aspergillus niger was obtained with an initial tannic acid concentration of 3% (w/v) at 35°C, Initial pH of 5.5 and a fermentation period of 96h.The substrates Betalnut husk and Plantain flower gave a maximum tannase production of 19.3 U/ml and 17.89 U/ml respectively.