The study of palm and rapeseed oil stability during frying

Palm oil is characterized by high oxidation stability, high smoke point, low foam making properties, limited penetration into the product, what makes it ideal for processes requiring thermal treatment such as frying. The aim of the study was to investigate the chemical composition and thermooxidative stability of red palm olein, rapeseed oil and their mixtures during deep-frying of French fries. Analysis of fatty acids composition and basic parameters of fresh oils (acid number, peroxide value, polar compounds content, induction time) were performed. During frying, changes in acid number, polar compounds in oils as well as consumers’ acceptance of the fries fried in these oils were investigated. During the 32-hour of frying, the lowest chemical changes occurred in palm olein, what was confirmed by low acid values (0.99 mg KOH/g) and low polar content (14.4%). At the end of the experiment, the oil mixture had the highest polar fraction value of 25.0%. In the opinion of consumers, fries fried in rapeseed oil were “the best”, while French fries fried on palm oil were considered “artificial”, “chemical” and “disgusting”. The reason for this opinion was the addition of β-carotene to this oil. On the other hand β-carotene from palm olein had a great positive effect on the colour of the fries, but at the same time had a negative effect on the taste.