Effect of Deep Frying of Potatoes and Tofu on Thermo-Oxidative Changes of Cold Pressed Rapeseed Oil, Cold Pressed High Oleic Rapeseed Oil and Palm Olein

Abstract

One of the commonly used food preparation methods is frying. Fried food is admired by consumers due to its unique taste and texture. Deep frying is a process of dipping food in oil at high temperature, usually 170–190 °C, and it requires a relatively short time. The aim of this study was to analyze the thermo-oxidative changes occurring during the deep frying of products such as potatoes and tofu in cold pressed rapeseed oils and palm olein. Cold pressed rapeseed oil from hulled seeds (RO), cold pressed high oleic rapeseed oil from hulled seeds (HORO), and palm olein (PO) (for purposes of comparison) were used. Characterization of fresh oils (after purchase) and oils after 6, 12, and 18 h of deep frying process of a starch product (potatoes) and a protein product (tofu) was performed. The quality of oils was analyzed by determining peroxide value, acid value, p-anisidine value, content of carotenoid and chlorophyll pigments, polar compounds, smoke point, color (CIE L*a*b*), fatty acids content and profile, calculation of lipid nutritional quality indicators, and oxidative stability index (Rancimat). Cold pressed high oleic rapeseed oil was more stable during deep frying compared to cold pressed rapeseed oil, but much less stable than palm olein. In addition, more thermo-oxidative changes occurred in the tested oils when deep frying the starch product (potatoes) compared to the deep frying of the protein product (tofu).

Assessment of the Physicochemical Properties of Fragrant Rapeseed Blended Hotpot Oil by Principal Component Analysis

“…During the transformation of the four blending oils into four hotpot blended oils, both AV and PV increased to different degrees. The AV increased by 0.35 (F4) -0.51 (F2) mg/g, while PV increased by 0.01 (F3) -0.03 (F1) g/100 g. These small increases in values were associated with certain hydrolytic changes; however, this process did not significantly affect the quality of the test oil, and similar observations were reported by other authors 30,31) . The changes to the physical and chemical properties of the four blended hotpot oils during boiling are shown in Table 2.…”

Fatty Acid Composition of Selected Street Foods Commonly Available in Malaysia

“…Other than the type of fat-based ingredients used in the local street foods, the absence of TFAs may also be explained by the cooking temperature used to prepare the foods. Most of the studied street foods are deep-fried using a cooking temperature below 200 °C [ 44 ]. A recent review [ 14 ] found that heating edible oils to below 200 °C, a common cooking temperature, does not affect the TFAs levels in the oil.…”

Black Elderberry Press Cake as a Source of Bioactive Ingredients Using Green-Based Extraction Approaches

“…The method has been employed to develop techniques for flour [ 24 ] and honey authentication [ 25 ]. The effect of deep-frying potato and tofu on thermo-oxidative changes in cold-pressed rapeseed oil, high-oleic rapeseed oil and palm olein was investigated by Wroniak et al [ 26 ], and a volatile profile for Kumpiak podlaski dry-cured ham during traditional ripening was developed by Karpinski et al [ 27 ].…”