Kamau J.M., Nanua J.N.
Abstract
On-farm processing of oilseeds using the manually operated ram press has spread to many rural areas in Kenya in
recent years. The products of the processing operation are semi-refined edible vegetable oil and protein cake.
This study was undertaken to determine storage stability of the oil. Sunflower oil was extracted using the ram
press and stored in glass and plastic bottles which were left either open or closed, were either fully filled or
with a headspace for a period of up to 6 months. Peroxide values and acid values were measured during the storage
period. Potato chips were deep fried in the different oils and subjected to pair and triangle comparison tests to
determine differences in texture and taste. After six months of storage, the peroxide value of the oils had not
exceeded 20 milli-equivalent peroxide oxygen/g. Acid values rose slightly with the maximum rise being from 0.52
to 0.82 milligrams KOH/g. There was no significant preference for potato chips fried in Saladin oil, ram press
oil or rancid sunflower oil at the 0.05 level. For long storage life, oil from on-farm processing should be stored
in colored bottles, fully filled and tightly closed.
Key words:
sunflower oil; semi-refined; ram press; storage stability, hydrolytic rancidity, oxidative rancidity