Studies on white cabbage (Brassica oleracea) powder prepared by three different drying techniques

Abstract

Cabbage is highly nutritious vegetable abundant in Bangladesh. In winter season vast amount of cabbage grown in Bangladesh. In this study three methods were taken for cabbage preservation such as oven drying, solar drying and freeze drying. Nutritional characteristics such as moisture, ash, fat, protein, carbohydrates and energy contents of samples (white cabbage powder) obtained from the methods were compared. Phenolic constituents along with antioxidant activities of the samples were also ascertained. Minerals such as calcium, phosphorous and iron percentages were also determined. The moisture content of white cabbage powder prepared by oven drying, solar drying and freeze drying methods were 19.60%, 17.85% and 15.3% respectively. The protein content of white cabbage powder prepared by oven drying, solar drying, freeze drying methods were 12.04%, 9.68% and 15.62% respectively. The fat content of white cabbage powder by oven drying, solar drying, freeze drying methods were 15.45%, 14.35% and 7.57% respectively. The ash content of samples by oven drying, solar drying, freeze drying methods were 4.99%, 5.58% and 4.41 % respectively. The Carbohydrates contents of resultant powder by oven drying, solar drying, freeze drying methods were 47.92%, 52.54% and 57.90 % respectively. The energy content of samples by oven drying, solar drying, freeze drying methods were 415 kcal/100gm, 386kcal/100gm and 370kcal/100gm respectively. The calcium percentage of white cabbage powder obtained from oven drying method was 9.50mg/100gm which was higher than that of the samples prepared by solar drying (7.79mg/100gm) and freeze drying (8.44mg/100gm). Sample prepared by freeze drying method were of high iron content (17.577mg/100gm) than the other samples such as oven drying (11.939mg/100gm) and solar drying (15.456mg/100gm). Highest (22.352mg/100gm) phosphorus was detected in powder prepared by solar drying method. Phosphorus in samples of oven drying method and freeze drying methods were 14.630mg/100gm and 11.480mg/100gm respectively. Samples obtained from oven drying method exhibited high total phenolic contents (393.1 mg and 366.3 mg gallic acid equivalents/100gm cabbage powder sample respectively. Total antioxidant activity was determined as 8.73 µg AAE/mg fw in sample of oven drying method and 10.59 µg AAE/mg fw in sample of freeze drying method.