A thesis submitted in partial fulfillment of the requirements for thedegree of Master of Engineering, School of Environment, Resources and Development

Thesis (M. Eng.) - Asian Institute of Technology, 2011

The antimicrobial is a substance that kills or inhibits the growth of microorganism. The antimicrobial substance can beorganic acid, hydrogen peroxide, carbon dioxide, diacetyl and bacteriocin.Lactobacillusplantarum(L. plantarum)was isolated fromfreshturmericrhizome(Curcuma longaLinn.). The antimicrobialsubstancesfrom Lactobacillus plantarumand Lactobacillus caseiTISTR 1463(L. casei)showed significant antibacterial activities against Escherichia coli, Salmonella typhimuriumand Staphylococcus aureus.The bacteriocin of L. plantarumwas purified by ammonium sulphate precipitation followed by dialysis through 1000 molecular weight-cut-off-dialysed membrane. The activity of bacteriocin from L. plantarum is 5,120 AU/ml, and was not affected when treated at 95°C for 10 min, and remained stable at pH 5 and pH 7. The molecular weight of bacteriocin from L. plantarumis approximately 1-2 kDa and 12-14 kDa. The bacteriocin from both strains was able toinhibit the growth ofindicator strains. L. plantarumand L. casei produced the maximum bacteriocin at 37 °C and 30 °C,respectively.The bacteriocinactivity fromL. plantarum was foundefficient than fromL. casei TISTR 1463.The unpurifiedextractsandpartially purifiedbacteriocin from L. plantarum were incorporated with cassava starch filmin the form of edible packaging. The surface of all typesof edible filmsbased onthe cassava starch wasrough andwithsmallridges all over the film. Addition ofextracts from L. plantaruminto the filmsignificantly (p{u02C2}0.05) reducedtensile strengthandincreasedelongation at break. On the other hand,addition of partially purified bacteriocin had not shown any changes in tensile strength and elongation at break as like of cassava starch film. In case of water vapor transmission (WVT) and water vapor transmission rate (WVTR), the addition of antimicrobial substance and bacteriocin into the cassava starch film increase significantly (p<0.05)WVT and WVTR.The various types of cassava starch based film were applied on thefresh fermented pork product. The result shows that the cassava starch film incorporated with the whole extracts could inhibit the growth of microorganism. However the cassava starch based film can be applied on the products for the short period because of the barrier properties problem. For the application, the bacteriocin from L. plantarum has ability to prolong the shelf-life of product.In case of pasteurized orange juice and pasteurized milk, there were not observed the growthof microorganism during period ofstorage on both products when incorporated with bacteriocin. On the other hand, for the control of both pasteurized orange juice and pasteurized milk, there were observed the growthof microorganism during period of storage.