55 Antioxidant Capacity and Phenolic Content of Amaranthus spp. Grown in Malaysia Amin Ismail * • Emmy Hainida Khairul Ikram Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia Corresponding author: * amin@medic.upm.edu.my Keywords: -carotene bleaching assay, bayam, blanching, DPPH assay, heat treatment ABSTRACT Amaranthus spp., locally known as spinach or “bayam”, is one of the most popular green vegetables consumed in Malaysia. Five types of “bayam” namely ‘bayam putih’ (Amaranthus spp), ‘bayam merah’ (Amaranthus gangeticus), ‘bayam itik’ (Amaranthus blitum), ‘bayam duri’ (Amaranthus spinosus), ‘bayam ekor kucing’ (Amaranthus caudatus) can be found in Malaysia. However, urban and rural community most commonly consumes ‘bayam putih ‘and’ bayam merah. Amaranthus spp. have high antioxidant capacity among other vegetables. Besides other traditional antioxidant components, ‘bayam’ is also a good source of phenolic compounds. These compounds are able to act as a potent antioxidant component in Amaranthus spp. This green leafy vegetable is cooked before being consumed. Cooking practices may affect the antioxidant capacity and phenolic content in vegetables. Major losses of antioxidant capacity and phenolic content of the fresh ‘bayam’ were observed after cooking processes (boiling) for more than 10 min. However, this depended on the species of ‘bayam’. The consumption of certain fresh vegetables is important to promote a high intake of antioxidant components. Minimal heat treatment in cooking practices should be recommended to prevent the major loss of antioxidant properties and also to maintain safety and quality. 1. INTRODUCTION Vegetables are rich in certain vitamins and minerals, dietary fibers, and a variety of phytochemicals. A remarkable aspect of vegetables is that their benefits appear to promote health and prevent diseases (Potter 2000). Vegetables and fruits account for only a relatively small part of our caloric intake (5-10% of total calories) in most populations, however, the significant health benefits associated with their intake, especially their role in antioxidant activity, are being increasingly appreciated. There is a highly significant negative correlation between the intake of fruits and vegetables and the incidence of diseases (Papas 1999). Antioxidants in vegetables have been suggested to play a preventive role in the treatment of cancer and cardiovascular diseases. These foods contain a substance that plays a role in protecting other molecules from being oxidized. Their principle function is to inhibit or delay the oxidation of other molecules by inhibiting the initiation or propagation of oxidizing chain reactors by free radicals that might cause oxidative damage in our bodies (Jadhav et al. 1990). The occurrence of such oxidative damage might be a significant causative factor in the development of many human diseases. Vegetables are good sources of natural antioxidants. They are easily available from markets, inexpensive, easily cooked and rich in several nutrients that are essential to human health. The high antioxidant activity of vegetables is due to the presence of vitamins and provitamins such as ascorbic acid, tocopherols and carotenoids, but in addition, they are also rich in a wide variety of phenolic compounds. Malaysian markets offer a variety of vegetables ranging from leafy to tubers, for local consumption. The common vegetables consumed by the population of Malaysia include cruciferous vegetables (such as red cabbage (Brassica oleracea var. capitata rubra), Chinese cabbage (non-heading cabbage) (Brassica rapa pekinensis var cylindrica), green cabbage (Brassica oleracea var capitata), mustard cabbage (Brassica juncea var rugosa) and Chinese white cabbage (Brassica rapa var chinensis)), kale (Brassica alboglabra), long beans (Vigna sesquipedalis), french bean (Phaseolus vulgaris), water cabbage (Ipomoea aquatica) and amaranth (Amaranthus spp.) (also known as spinach). Generally, most people consume cabbage, water cabbage, amaranth and shallot. The household consumption survey by Federal Agricultural Marketing Authority (FAMA) in 1991 showed that the consumption pattern was based on regions in which there is an urban preference for cabbage, kale and amaranth compared to rural region. Based on our Nutrient Composition of Malaysian Foods, these vegetables have been reported to contain about 1825-4760 g of – carotene/100 g edible portion and 27-107 mg of vitamin C/100 g edible portion (Tee et al. 1997). Consumption of vegetables per capita Malaysian is 37.6 kg per year (FAO 2002). Malaysia per capita annual consumption of vegetables in 1991 showed that per capita Malaysian consumes 2.45 kg of amaranth (Mubarik 1996).