The influence of different heat treatment on the vitamin C content in pepper (Capsicum annuum L.)

Abstract

The pepper (Capsicum annuum L.) is vegetables commonly used in the human diet. Due to its exceptional sensory and nutritional properties, it is readily consumed both fresh and processed into various ready meals, pickling, salads, dried spices, etc. There are a large number of cultivars of peppers that differ in shape, size, color, aroma, degree of hotness, etc. The pepper is rich source of carotenoids, vitamins, mineral matter, carbohydrates, organic acids and aromatic components. Numerous bioactive compounds found in pepper, such as vitamin C (ascorbic acid), contribute to its high antioxidant activity. The aim of this study was to determine the vitamin C content after different heat treatments commonly used in industrial processing of peppers, as well as in the household. The domestic cultivar “Elephant ear” was subjected to tree different thermal treatments: 1) cooked in closed and opened dish, 2) roasting in microwave oven and on the hob, and 3) frying in sunflower oil, during 15 minutes. The content of vitamin C was determined using indirect iodimetry method. The results were expressed in mg/100 g dry basis (d.b.) and compared with the fresh pepper used as a control. The content of vitamin C in the fresh sample was 1295.38 mg/100 g d.b., while in the peppers cooked in closed and opened dish its value was 1007.58 and 615.17 mg/100 g d.b., respectively. In the pepper threated in microwave oven and on the hob, the content of vitamin C was 494.51 and 1201.40 mg/100 g d.b., respectively, while its value in the fried sample was 443.65 mg/100 g d.b. The highest loss of vitamin C was observed after frying treatment (65.75%), while the lowest loss was recorded in the sample roasting on the hob (7.26%), in relation to the initial amount in unprocessed pepper. Also, the results of vitamin C content indicate that its loss was higher when the thermal treatment was performed in an opened then in the closed dish probably due to the increased presence of oxygen that may intensify oxidation. However, the obtained quantity of vitamin C per mg/100 dry basis of the tested samples is more than enough to ensure daily intake of vitamin C and avoid its deficiency in human diet.