| dc.description.abstract | The study was conducted to assess the effect of different storage temperatures and durations on physicochemical properties including total dissolved solids, pH, and formaldehyde of four bottled water brands designated A, B, C, and D marketed in Kampala city, Uganda. The study took place from 13th February 2020 to 17th March 2020. A total of 128 bottles containing 500ml of water each were purchased from different supermarkets. Testing for the physiochemical properties was done after zero, one, eleven, and thirty-three days of (i) direct exposure to the sunlight (18.1 ˚C to 28.7˚C), (ii) freezing at 4°C, (iii) chilling at 10°C, and (iv) storing the bottled water at room temperature The control experiment involved storing the bottled water in a dark room at the different storage durations under this study.
For pH, results show that there was no interaction between brand and duration of storage at a significance level of 0.05. There was interaction between brand and storage treatment, and interaction between storage treatment and duration of storage. Brand and storage treatment had a significant effect on the pH values. Duration of storage had no significant effect on the pH values. For bottles that were directly exposed to sunlight, the pH values varied from 5.92 to 6.52 and increased in all brands with increase in duration of storage. For bottles stored at room temperature and control experiment, pH increased with the increase in duration of storage and varied from 6.01 to 6.42 and 6.02 to 6.46 respectively. For the refrigerated bottles, pH values fluctuated from 6.15 to 6.52. pH values for bottles stored in a freezer fluctuated from 6.29 to 6.96. Only the pH values of bottles of water stored in a freezer after 33 days were within the WHO standards of (6.5- 9.5) for bottled drinking water. The rest were below the lower limit of the WHO standard.
For total dissolved solids, at a significance level of 0.05, results showed that there was no interaction between brand and duration of storage. There was also no interaction between storage treatment and duration of storage. There was interaction between brand and storage treatment for total dissolved solids. Duration of storage had no significant effect on the concentrations of total dissolved solids. However, brand and storage treatments had significant effects on the concentrations of total dissolved solids. When directly exposed to sunlight, the values of total dissolved solids increased with increase in storage time and fluctuated from 32.4mg/L to 70.1mg/L in all the tested brands. They also increased and fluctuated from 31.8mg/L to 67mg/L and 31.1mg/L to 63 mg/L for bottles that were stored at room temperature and in the control experiment respectively. For refrigerated bottles, the total dissolved solids level decreased with increase in storage time and fluctuated from 30.9mg/L to 57.7mg/L in all the bottled water brands. The levels of total dissolved solids decreased with increase in storage time for bottled stored in a freezer varied from 33.9mg/L to 77.6mg/L. In all the various storage treatments, the values of total dissolved solids were within the WHO acceptable limits of 1000 mg/L related to bottled drinking water quality.
For formaldehyde, results show that there was no interaction between brand and storage treatment at a significance level of 0.05. There was also no interaction between brand and duration of storage. There was interaction between storage treatment and duration of storage. All the factors brand, storage treatment, and duration of storage had no significant effect on the levels of formaldehyde. When bottles were directly exposed to sunlight, the levels of formaldehyde increased with increase in storage duration in all water brands and fluctuated from 0.320% to 0.453%. At room temperature, the concentrations of formaldehyde increased with increase in storage time and ranged from 0.27% to 0.29% due to the effect of migration of formaldehyde from the polyethylene terephthalate (PET) material into the water. In the control experiment, the concentrations of formaldehyde ranged from 0% to 0.296%. For the bottles stored in a freezer, the concentration of formaldehyde varied from 0.263% to 0.295%. The levels of formaldehyde at various storage treatments were within the WHO limits of bottled drinking water of 900 μg/L.
The findings indicate that the concentrations of formaldehyde and total dissolved solids could be elevated with increased storage time and exposure to sunlight. The values of pH decrease when directly exposed to sunlight, at room temperature, and in the control experiment with increase in storage time. | en_US |
