Influence of Packaging Materials and Storage Conditions on the Vitamins A and E Storage Stability of Palm Oil in Nigeria

Aims: Despite the presence of natural antioxidants contained in palm oil, it is still susceptible to quality deteriorations if not properly stored. This study therefore evaluates the storage stability of vitamins A and E in palm oil in four prominent packaging materials (metal cans, white plastic bottles, glass bottles and pet bottles) used in Nigeria and under three storage conditions [(refrigeration (5ºC), closed cupboard (27ºC) and direct sunlight (35ºC)].

Study Design: Freshly produced palm oil was filled in metal cans, white plastic bottles, glass bottles and pet bottles and stored in open, direct sunlight (35±1ºC), closed wooden cupboard (27±1ºC) and a refrigerator (5±1ºC) for a period of 120 days The samples were stored in a 4 (packaging materials) x 3 (Temperature) factorial arrangement making 12 treatments for each analysis sampled every 30 days for a period of 120 days. Vitamins A and E contents of palm oil samples were determined at 30 days intervals using ultraviolet spectrometer and high Performance Liquid Chromatography, respectively. Data values of triplicate determinations of vitamins A and E contents obtained from analysis were subjected to analysis of variance (ANOVA) and mean values were separated using Duncan New Multiple Range (DNMR) test using the Statistical Package for Social Sciences (SPSS) version 17.0. The rates of changes in the Vitamins A and E contents over the storage period of 120 days were also determined using Linear Regression analysis.

Place and Duration of Study: Department of Food Science and Technology, Federal University of Technology, Akure, Nigeria between January, 2012 and December 2013.

Methodology: Palm oil filled into the four different packaging materials was stored in the three storage conditions for a period of 120 days. Vitamins A and E contents of palm oil samples were determined at 30 days intervals using ultraviolet spectrometer and high Performance Liquid Chromatography, respectively. Data obtained were subjected to Analysis of Variance (ANOVA) to determine the statistical significant differences in the packaging materials and the storage conditions and the interactions between them. Mean values of vitamin A and vitamin E of different packaging methods and storage conditions were separated by Duncan New Multiple Range (DNMR) test to indicate their levels of significant differences. Linear Regression Analysis was also performed to determine the rates of changes in the vitamin A and E with time during storage.

Results: The vitamins A and E content of the samples stored in open, direct sunlight were virtually lost at the end of the storage period. For samples stored in sunlight, the vitamin A values in metal cans decreased by 97.45%, in white plastic bottle by 92.19%, in glass bottle by 92.46% and in pet bottle by 93.13% while vitamins E also decreased by 92.31%, 61.54%, 75.48% and 82.05%, respectively. Samples stored at room temperature suffered a higher amount of losses compared to the refrigerated samples. The refrigerated samples recorded only a minimal amount of loss. For the storage in both the sunlight and the dark cupboard and storage under refrigerating temperature of 5ºC, the order of preference for the packaging materials was white plastic bottle > glass bottle > pet bottle > metal can.

Conclusion: The results obtained from this study have demonstrated that packaging palm oil in white plastic bottle is the best method of preserving palm oil under refrigerating condition and lacquered metal under sunlight and dark cupboard. It has also shown that vitamins A and E degrade faster when palm oil is stored under sunlight and totally unfit for human consumption at the end of the storage period hence, palm oil should be stored in cold, dry places to limit their losses of antioxidant components.