Compounding of polylactides (PLA) and polybutylene succinate (PBS) was performed with the aim of modifying the processablility of PLA based materials. The influence of PBS on the thermal, mechanical, and rheological properties of PLA/PBS blends was analyzed and the results of the testing were used to indicate the compatibility of the blend. A decrease of the melting temperature and an improvement of the mechanical properties of PLA were achieved by compounding it with PBS. Increasing addition of PBS was found to decrease the tensile strength and Young's modulus of the PLA/PBS blends, but its % elongation at break was increased. However, a higher level of PBS addition initiated a phase separation problem. The interaction parameters were calculated from the Flory-Huggins equation for prediction of thermal property of the blends and the maximum blending ratio of 80:20 (PLA:PBS) was thermodynamically acceptable immiscible level. Relatively low levels of PBS addition improved the melt flow characteristics of the blend. The effect of the PBS addition level on the compatibility of the blend can definitely identify from the modified Cole-Cole plot of rheological properties.

Microbial recontamination in post- harvest products, specifically for fresh cut fruits and vegetables, often raises concern of consumer health safety since pathogen bacteria readily forms sticky biofilm for their protection that often render ineffective of cleaning or disinfection process. Therefore, tracking biofilm rather than bacteria cells may also be used for indication of microbial recontamination. This research focuses on acquisition of spectroscopic imaging and information for E. coli biofilm adherent on green oak leaf at microscopic level for visible bandwidth. A confocal laser scanning microscope (CLSM) was applied to investigate for the evident of biofilm formation. In order to enhance spectroscopic signal, staining surface sample with propidium iodide, commonly used for staining dead cell, was specifically investigated to a potential use for determination of E. colis biofilm as an evident of recontamination occurrence. Green oak leaf samples were inoculated with a small drop of viable E. coli of 2.7x109 CFU/ml covering around 7x7 mm2 and all samples were spectroscopic imaged every day for 7 days. Absorbance spectrum acquired by CLSM for the E. coli inoculated samples presented three identity peaks at wavelengths of 620, 670, and 690 nm but the latter identity wavelength appeared to include common autofluorescence of leaf surface physiology so arguable interpretation is unavoidable for 690 nm. In opposite, the identity peaks at 620 and 670 nm presented strong detection of E. coli ‘s biofilm for storage time beyond day 5 at a significant level of confident 99%. However, the lowest minimum detection limit in term of E. coli concentration required more precisely experimental validation.