Effect of vacuum drying on chemical quality of bitter gourd

It is the second largest producer of fruits and vegetables in the world, after China. Bitter gourd has twice the calcium and potassium of spinach and banana respectably. It is rich in iron, zinc and good in phosphorus, sodium, magnesium. It is a fair source of vit. C contributes about 55% of total vitamins. Present study was conducted to investigate the effect of effect of vacuum drying on chemical quality of bitter gourd. Mature bitter gourds of uniform medium size and dark green colour were procured, washed and sliced into 1, 2 and 3 cm thick rings with stainless steel knife. After preparation slices were blanched in boiling water at 90°C for 2 minutes. Sulphitation by dipping the blanched bitter gourd slices in 0.2% KMS, 0.2% KMS + 1% Na₂SO₃, 0.1% KMS + 0.05% Citric acid solution for 10 min at room temperature. Salt treatment was given; they were blanched by boiling in 5% NaCl solution. Pretreated bitter gourd slices were spread on a stainless steel tray and dried in vacuum oven dryer at different temperatures 50, 60, 70, 80 °C till bitter gourd crisp or brittle. The lower rehydration ratio of dried sample was found at higher temperature and longer drying time required for drying conditions. DPPH inhibition activity was found lower in all dried samples than fresh. In vacuum oven drying, samples dried at 50 and 60 °C were found to retain higher total phenolic content than 70 and 80 °C.