Choice of Simple Methods for Quality Control of Frying Fat during Deep Frying of Potato Products

Studies have been carried out to choice methods which could assess in best way the complex changes in fat during deep frying of French fries and potato crisps. A special emphasis was laid on the estimation of usefulness of simple and quick “methods” which could practically indicate the utilization time of fats (soybean oil, low erucic acid rapeseed oil, ?Sofryt”? -hardened soybean oil), used in deep-fat frying of potato products. Besides the oxidized fatty acid content, proposed by DGF (German Society for Fat Science) as a basic test for the quality assessment of used frying fats, following control tests during the deep-fat frying of potato products have been appointed: colour tests with bromthymol blue and 2,6-dichlorphenol-indophenol, sensoric evaluation, dielectric constant and colour by iodine scale. For these tests suitable limits, qualifying the utility of oils and fats for further frying of French fries and potato crisps, have been estimated.