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This study was carried out to determine the effects of packaging materials and storage periods on seed quality and longevity dynamics of an endangered tropical tree species, Pericopsis elata. The experimental period was December, 2015 to June, 2016. Seed collection was done at the Bobiri Forest Reserve. The seed storage experiment was set up using 3 x 6 factorial arrangements in Completely Randomized Design with three replications. Six packaging materials (jute, nylon, paper, ziplock bag, airtight bottle and no packaging) and three storage periods (no storage, three months storage and six months storage) were used. Germination percentage, seed vigour, 1000 seed weight, moisture content, carbohydrate, protein and oil contents were assessed before storage, three months and six months after storage. P. elata seeds with initial moisture content of 7.5% and packaged in airtight bottle and ziplock bags maintained their moisture contents even as storage periods increased. The initial amounts of seed carbohydrates (1.9%), proteins (37.4%) and oil (31.3%) were maintained in the airtight packaging materials (bottle and ziplock bag) thereby improving seed storability. The seed viability equation predicted that P. elata seeds could be stored for 243 years after six months of storage. Seed viability dropped to 164 days after the accelerated aging test was performed on the six-months old stored seeds. The study concluded that the seeds of this important endangered tree can be stored in airtight containers before the next planting season without any loss in seed quality.
Degree of poly (lactic acid) (PLA) foil degradation by the filamentous fungi i.e. Aspergillus ustus, A. sydowii, A. fumigatus, Paecilomyces lilicanus and Penicillium verrucosum has been investigated. A degradation process has been conducted in dynamic conditions at 30°C for 10 days in a medium containing 0.1% of foil as carbon source. To activate the enzymes involved in the poly (lactic acid) foil degradation, triple passaging on the medium has been conducted. Each passage lasted 10 days. After passages, increase of the mycelium biomass, its enzymatic activity and structural foil changes have been investigated using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Strain passaging has resulted in the activation of the enzymes of the esterase group responsible for foil degradation, expressing itself in the mycelium biomass increase. Penicillium verrucosum and Aspergillus ustus appeared to be the most active strains. Structural and thermal changes of the material have been demonstrated. Filamentous fungi have a wide range of enzymes of the esterase group which, following initial activation, may actively participate in PLA foil degradation.
Engineering of a biobased package or packaging material requires knowledge of the processing and material properties of the polymers. If the properties of the native biopolymer are not identical to the required one, or if the polymer by nature is not thermoplastic, a certain modification of the polymer must take place. For very specific requirements (very low gas permeability or high water resistance) it is unlikely that one polymer will be able to provide all required properties even after modifications. Hence, it is necessary to use multiple materials in a composite, a laminate or co-extruded material.
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