Effect of sunlight exposure and packaging material on the quality and oxidative stability of palm olein, palm oil, and soyabean oil commercialized in Cameroon

Abstract

Background: In Cameroon oils and fats are generally packaged in translucent polyethylene bottles of 1L volume and non-translucent polyethylene containers of 5, 10, and 20 L. The translucent bottle is more solicited as it attracts the customer better. In the local market, for advertising purpose, these oils are exposed to sunlight the whole day. This can affect their quality and put consumer health at risk. It is important to suggest packaging materials which under such conditions can limit the alterations and propose the best storage conditions.

Aims: The objective of this study was to evaluate the effect of ambient, sunlight storages and the types of packaging materials on the quality and stability of palm olein, palm and soybean oils.

Methods: About 2.5 L of each oil was divided into three portions, 1.2, 1.2 and 0.1 L. The portion of 0.1 L served as control in order to have the initial quality of the oils. The other two portions of 1.2 L were  respectively divided into nine (09) portions of 130 ml and introduced in three translucent polyethylene bottles (TPEB), three non-translucent polyethylene bottles (NTPB), and the last three in brown dark glass bottles (BDGB). The first set of nine (09) was stored in the dark at ambient temperature while the other set was exposed to sunlight radiations for 30 days, 8 h exposure/day. Samples from both ambient and sunlight storage were collected after every 10 days to analysis their quality and stability (color, peroxide, p-Anisidine, TOTOX, thiobarbituric, acid values and Fourier Transformed Infrared Spectrocospy).

Results: Results showed that sunlight reduces the color in the L and b* value of palm oil. Sunlight also increase in a significant way the peroxide, p-anisidine, TOTOX, Thiobabituric acid values of the analyzed oils compared to ambient storage. Palm oil extraction process significantly increases its acidity. The Fourier transformed infrared spectra showed little differences with soybean oil being the most altered. BDGB and NTPB were found to protect better quality oil the tested oils compared to TPEB under sunlight.

Conclusions: Oils sold in the market should be packaged in NTPB or BDGB so as to reduce the impact of sunlight and limit photo-oxidation reactions.

Keywords: palm oil, soybean oil, palm olein, packaging material, sunlight, oxidation