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.

An existing small-scale single-powered baking oven was modified and optimize into a dual-powered oven. The oven was redesigned to accommodate the initially designed firewood heat source and the newly introduced gas heat source. Four heat exchangers (thermal pipes) were introduced to the baking chamber for effective heat and mass transfer during baking of bread dough. The thermal pipes were made of 2 mm thick hollow galvanized steel pipe of 23 mm diameter and 660 mm length. The performance of the oven was evaluated using the standard performance index, which includes baking capacity, baking efficiency and weight loss of the baked bread. The baked bread's physical properties were determined and analyzed using Duncan multiple range ANOVA test at significant level of p < 0.05. These properties were optimized to determine the generate regression models using 3D model plot. The baking capacity, baking efficiency, weight loss and optimum baking temperature were: 101.9 kg/h, 46.44% (wood-fired); 70.34% (gas-fired), 13.5 g (wood-fired); and 25.5 g (gas-fired), 150˚C, respectively. The physical properties of baked bread, wood-fired were found to correspond with that of gas-fired oven. The modified oven can be used for the baking of dough at domestic, small and medium scale bakery.