Effect of Freeze-Drying Pretreatment on the Nutritional Quality of Plantain Chips During Deep-Fat-Frying

This project determined the effect of freeze-drying pre-treatment on the nutritional quality (carotenoid contents and vitamin C etc) of plantain chips during deep fat drying. The objectives include: to subject the plantain slices to freeze-drying pretreatment, to subject the freeze-dried and untreated (without freeze-drying pretreatment) plantain chips to deep fat frying, to determine the effects of freeze drying on the proximate composition of plantain chips, to determine the effects of freeze drying on the nutritional properties (carotenoid, vitamin C and potassium) of plantain chips and to compare the nutritional quality of fried pretreated and untreated plantain slices. The plantain was sliced into 3g size using slicing machine (SL524B, Cuisinart Inc. UK) and of the thickness 3mm. It was freeze-dried using freeze dryer at the temperature of -34 oC for 16h. The sliced plantain was fried in a deep fat fryer (Kitchen Perfected Company Ltd., Lloytron, Uk) of capacity 1.0 L. The frying temperature was 160oC at the frying time of 2, 4, 6, 8 and 10 min. From the results of this research study, fresh plantain slices had the vitamin C content of 9.92 mg/100g. When plantain was deep fat fried for 2 min, the vitamin C content was reduced to 5.34 mg/100g, on further increase in frying time, the vitamin C was increased to 12.92 mg/100g at 10 min. There was no significant difference (P>0.05) between the frying time of 8 min and fresh samples suggesting 8 min to be the best time of frying for retention of the vitamin C content of plantain slices. The carotenoid content of fresh plantain slices was 13.89 μg/g, there was no significant difference (P>0.05) between the carotenoid content of fresh plantain slices and that of 2 min frying time. On increase of frying time to 4, 6 and 8 min, the carotenoid content reduced with increase in frying time. However, at 10 min frying time the carotenoid content was increased to 14.53 μg/g. The initial moisture content of the sample after deep fat frying for 2 min was recorded as 87.97%. The moisture content reduced to 75.56% as the time of frying was increased to 4 min. It was observed that as the time of frying was increased, the moisture content of fried plantain slices was reduced. A final moisture content of 1.86% was obtained after 10 min of frying in this research.