Barrier potential of plastics used for packaging water (sachet), to microbial growth and survival
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Date
2018-11-15
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Abstract
Packaging, the technology of enclosing or protecting products for distribution, storage, sale, and use, is gaining growth in the food industry in Ghana. Drinking water, for instance, is packaged in plastic sachet or plastic bottles with Low Density Polyethylene (LDPE) and High Density Polyethylene (HDPE) being the two kinds of polyethylene plastics used for the packaging of sachet water. This study evaluated the barrier potentials of these polyethylene’s, used in packaging sachet water, to microbial growth and survival. A water packaging company was contracted to package treated water from one source and of same quality into the LDPE and HDPE packaging types. They were stored under three storage conditions (refrigeration, room temperature, and sunlight) for a period of six (6) weeks. It was observed that, pH of the samples decreased insignificantly for both packaging types (p>0.05) at the end of the investigation. For the Low Density Polyethylene (LDPE), the Total Plate Count (TPC) in the LDR (low density polyethylene under room temperature storage) increased from log 2.22 cfu/ml to log 2.33 cfu/ml while that for the samples in LDF (low density polyethylene under refrigeration), increased from log 2.22 cfu/ml to log 2.54 cfu/ml. The TPC for samples from the LDS (low density polyethylene under sunlight exposure), decreased from log 2.22 cfu/ml to 1.80 cfu/ml. For the High Density Polyethylene (HDPE), the TPC for the samples from the HDR (high density polyethylene under room temperature) increased from log 2.22 cfu/ml to log 2.98 cfu/ml whilst a decrease from log 2.22 cfu/ml to log 2.12 cfu/ml was observed in the samples from the HDF (high density polyethylene under refrigeration). For the samples from the HDS (high density polyethylene under sunlight exposure), there was a decrease from log 2.22 cfu/ml to log 0.57 cfu/ml. Generally, it was observed that increase in temperature resulted in significant increase in TPC (p<0.05). Coliforms were not detected in any of the samples investigated. The study revealed that, HDPEs used for packaging sachet water provided better barrier to microbial contaminants than the LDPEs.
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A thesis submitted to the Department of Food Science and Technology, College of Science, in partial fulfilment of the requirements for the degree of Master of Science in Food Quality Management.