Effects of Direct and Indirect Sunlight on Polythene Packs, Sensory, Microbial and Chemical Properties of Sachet Water

Abstract

The use of Polyethylene or Polyethylene terephthalate (PE/PET) packaging bags for water in Nigeria has great marketing appeal to consumers. However, poor storage and display techniques could subject these products to microbial, physical and chemical deterioration. Sachet water samples commonly taken by staff and students of the Federal College of Agriculture, Ibadan were subjected to different storage conditions for three and five days. Physicochemical parameters of each water sample were determined through equilibrated devices and titrimetric or colorimetric assays, while aerobic bacteria were isolated through pour-plate method in Nutrient Agar. Exposure of sachet water to sunlight had significant effects on their physical, chemical and bacteriological properties. Highest chloride, calcium, alkalinity, hardness, sulphate and total dissolved solids (13.04 mg/L, 123.53 mg/L, 9.08 mg/L, 33.00 mg/L, 27.59 mg/L and 78.33 mg/L, respectively) were recorded in water samples exposed to indirect sunlight for 5 days. Samples stored at room temperature had the best physicochemical properties. Exposure to sunlight reduced the colony forming units of aerobic bacteria in all the water samples. Lowest bacterial count (0.33 × 103 CFU/mL) was observed in water sample exposed to sunlight for 5 days, while the highest count (55.84 CFU/mL) was recorded in samples stored at room temperature. Sensory scores of water samples ranged between 8.33 and 10.00; however, these sensory properties were not significantly affected by their exposure to sunlight for up to 5 days. Sunlight exposure negatively affected the inner surface feel of water packs, sachets appeared slimy after direct and indirect exposure. The physicochemical and microbial changes observed in sunlight-exposed sachet water samples did not influence their organoleptic acceptability. Consequently, in addition to taste and biochemical analysis, the feel of water sachets could be an indication of structural disintegration and water contamination. In order to maintain the integrity of sachet water, products should be hygienically prepared and prevented from sunlight exposure during transportation and storage.