Optimizing Oil Reduction in Fried Eggplant Rings

The effect of thermal pretreatment using water or steam blanching; and chemical pretreatment by soaking in SO2, chitosan, carboxy methylcellulose (CMC) or sodium chloride (NaCl) on moisture content, oil uptake, sensory evaluation, colour, electronic structure and frying quality of eggplant rings were investigated. Eggplant rings were blanched for 3min in water and steam, and soaked in 2% chitosan and CMC, 4% NaCl and 0.1% SO2 solutions (25 C) previous to frying, to study the effect on oil uptake, moisture content, colour and structure using electronic microscope. Sensory responses indicated the best texture and lowest oil uptake at 4% NaCl solution for 20 min. Soaking had no effect (P<0.05) on color (L*, a* and b*) or moisture and oil loss during deep frying at 180 C for 4min. Sensory acceptability was not different (P<0.05) between the soaked product and a thermal sample. Frying eggplant rings at 180°C for 4 min was able to optimize the quality of eggplant rings regarding to L*, a*, C*, BI, ΔE-values and non-enzymatic browning (A420 nm).The oil uptake effect of various thermal and chemical pretreatments on eggplant rings was found to decrease in the following order water blanching > coated CMC > steam blanching > coated chitosan > SO2 > sodium chloride > untreated samples. The fried pre-treated eggplant rings with coated CMC and water blanching gave lower moisture (2.19) and oil (7) content (% on dry matter) compared to other pre-treated samples. It is evident that fried eggplant rings after chemical (chitosan, CMC, salt and So2) and thermal treatments (steam and water blanching) contained numerous types of cellular fragments using electron microscopy. These results indicate that coating CMC and water blanching exhibited oil barrier properties and did not significantly affect the flavor of the product, irregardless of breading type, thus making it a promising alternative in lowering oil content of fried foods.

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