Sajeev, M SEdwin, K WilsonKAU2019-12-202019-12-202015http://krishikosh.egranth.ac.in/handle/1/5810138108PGCassava forms an important food crop in the tropical countries and are rich in starch (20-40%) having desirable physico-chemical and functional properties. Starch and starch derivatives form an important constituent in biodegradable film preparation due to its renewability, abundance availability, low cost, film forming properties, high oxygen barriers, odorless, tasteless, colourless, nontoxic, low solubility, biodegradability etc. But films from the native cassava starch often possess poor physico-mechanical and hydrophobic properties. Hence modified starches by chemical, physical and enzymatic methods offer better scope for the production of biodegradable films which has got wide applications in the food packaging industry. The objectives of the present study was to find out the film forming properties of enzymatically modified cassava starch viz., liquefaction by -amylase and debranching by pullulanase enzymes added with glycerol as plasticiser. Rheological properties were measured in terms of the dynamic mechanical spectra of the film forming solutions viz., storage modulus, loss modulus, phase angle and complex viscosity. Filmogenic solutions based on -amylase was prepared with starch 5%, glycerol 20%, amylase concentration: 100, 200 and 300 μl from the stock solution (0.l ml amylase in 100 ml distilled water), temperature: 80, 85 and 90°C and time: 20, 30 and 40 min for gelatinization. For developing the pullulanase modified starch based films, the starch (5%) was incubated with pullulanase at 2, 3 and 4 units concentrations at 45, 50, 55 0C for 8, 16 and 24 h and the filmogenic solutions added with 20% glycerol were gelatinised at 90 0C for 20 min. Both the experiments were designed using response surface methodology using Box- Behnken design. The physico-mechanical, functional hygroscopic, biodegradation and storage studies of the films were carried out. The dextrose equivalent of the filmogenic solutions varied between 1.6-8.4 with the amylase and 2.2-16.0 with the pullulanase treated starch. The higher values of storage modulus, complex viscosity and low phase angle of the solution containing 153pullulanase treated starch compared to -amylase treated solutions showed that the gel formed during gelatinization of the solution is having more solid nature in their visco-elastic character. The films containing -amylase treated cassava starch showed better whiteness properties. Thickness, moisture content, tensile force, elongation at break and swelling capacity of the films containing pullulanase treated starch was higher than that of the films with -amylase treated starch. The higher solubility of the -amylase based starch films helps easy degradation of the films in the soil whereas offers poor packing ability. Pullulanase film‘s packing ability is better owing to low permeability and solubility. Though the films with both the modified starch is easily biodegradable, pullulalanase took 4 weeks for completely degrade into the soil as evidenced from the soil burial test. The microbial analysis studies showed that the soil in which -amylase treated film buried for degradation had highest bacterial, fungal and actinomycetes population than that of the soils with pululanase treated films. Considering various physical, mechanical and functional properties, the pullulanase modified starch offers better scope for the production of biodegradable packing materials.ennullThesis