Study by means of 1H nuclear magnetic resonance of the oxidation process in high oleic sunflower oil and palm oil during deep-frying of fish cakes.

This study aimed to compare the frying performance of palm oil (PO) and high oleic sunflower oil (HOSO) during frying aquatic products. The quality change and frying performance of HOSO and PO during frying of fish cakes were investigated. The oxidation and hydrolysis products of both oils were explored by the nuclear magnetic resonance technique. The results showed that the color deepening rate of PO was higher than that of HOSO. After 18 h of frying, the total polar compound content of PO and HOSO reached 25.67% and 27.50%, respectively. HOSO had lower degree of oxidation than PO after 24 h of continuous frying. The polyunsaturated fatty acid content in HOSO and PO significantly decreased. The oleic acid content in HOSO remained above 80% during the frying process. The major aldehydes in both oils were (E, E)-2,4-alkadienals and n-alkanals and glycerol diesters (DAGs) were abundant in PO. Furthermore, the addition of fish cakes had slight effect on the quality of the frying oil. Therefore, HOSO is an appropriate candidate for frying owing to its excellent frying stability and nutritional value.

Formation of AGEs in Penaeus vannamei fried with high oleic acid sunflower oil.

Here, we investigated the effects of frying process on the formation of advanced glycation end products (AGEs) in shrimps using Penaeus vannamei as the raw material. The results showed that the oil, malondialdehyde, fluorescent AGEs, carboxymethyl lysine (CML), methylglyoxal hydroimidazolone (MG-H1) and the outer layer carboxyethyl lysine (CEL) content was higher in the fried shrimps than that in the raw unfried shrimps. The outer layer CML, CEL and inner CEL, MG-H1 values all reached the maximum after the first batch of frying (22.43 mg/kg, 304.24 mg/kg, 83.76 mg/kg, and 169.42 mg/kg respectively). However, fluorescent AGEs and MG-H1 of the outer layer reached the maximum after the fifth and fourth batches of frying (1230.0 AU/g and 341.63 mg/kg). Malondialdehyde, fluorescent AGEs, CML, MG-H1, and CEL concentration in the fried shrimps firstly increased and then decreased to stabilization with more frying batches, with higher content in the outer layer of fried shrimps.

Changes in the Quality of High-Oleic Sunflower Oil during the Frying of Shrimp (Litopenaeus vannamei).

Shrimp fried in vegetable oil is a very popular food, so it is important to study the changes in the quality of the oil during frying. In order to more precisely study the nature of frying oil during the cooking process, this study investigated the quality changes of high-oleic sunflower oil during the frying of South American white shrimp (Litopenaeus vannamei). The oxidation and hydrolysis products of frying oils were investigated by integrating the proton nuclear magnetic resonance technique with traditional oil evaluation indexes in an integrated manner. The results showed that the color difference as measured using the ΔE* value increased gradually during the process. Moreover, the acid value, carbonyl value, and total oxidation significantly increased with prolonged frying time. The major oxidation products formed during frying were (E,E)-2-alkenals, (E,E)-2,4-alkadienals, and E,E-conjugated hydroperoxides. This indicated that longer treatment times corresponded with an increased accumulation of aldehydes and ketones, and an increased degree of oxidative deterioration of the oil. However, the proportion of oleic acid in the frying oil increased with the frying of shrimp, reaching 80.05% after 24 h. These results contribute to our understanding of the oxidative deterioration of high-oleic oils during frying, and provide an important reference for the application properties of high-oleic oils.

Monitoring the oxidation process of soybean oil during deep-frying of fish cakes with 1H nuclear magnetic resonance.

The oxidation process of soybean oil (SBO) during frying fish cakes was investigated. The TOTOX value of before frying (BF) and after frying (AF) was significantly higher than control (CK). However, the total polar compound (TPC) content of AF reached 27.67% in frying oil continuously frying at 180℃ for 18 h, and 26.17% for CK. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) loss in isooctane and methanol significantly decreased with the extension of frying time and then tended to be stable. The decrease of DPPH loss was related to the increase of TPC content. Antioxidant and prooxidant balance (APB) value below 0.5 was obtained after 12 h for heated oil. (E)-2-alkenals, (E, E)-2,4-alkadienals, and n-alkanals were dominant ingredients among the secondary oxidation products. Traces of monoglycerides (MAG) and diglycerides (DAG) were also detected. These results may improve our understanding of the oxidation deterioration in SBO during frying.

Effects of Konjac Glucomannan on Oil Absorption and Safety Hazard Factor Formation of Fried Battered Fish Nuggets.

The purpose of this study was to investigate the effects of konjac glucomannan (KGM) on oil absorption and the formation of safety hazard factors in fried battered fish nuggets by measuring advanced glycation end products (AGEs) and acrylamide contents. Other physicochemical properties were determined to explore the reason for oil absorption and formation of safety hazard factors. The acrylamide was found mainly in the crust. The addition of 0.8% KGM could significantly reduce the acrylamide content (p < 0.05). For the battered sample, the AGEs content was far lower than the unbattered. The addition of 0.8% KGM could significantly reduce the AGEs content in the inner layer (p < 0.05). The microstructure showed that the sample with 0.8% KGM had the most compact crust. The compact crust reduced oil and malondialdehyde contents. Combined with the other indicators, the inhibitory effect of 0.8% KGM on acrylamide was closely related with the decreased extent of oil oxidation and Maillard reaction in the samples with 0.8% KGM. The inhibitory effect of 0.8% KGM on AGEs might originate from its lower oil content.