Eggplants (Solanum melongena L), are native to the South East Asian region and were first domesticated there over 4000 years ago. In fact, the eggplant’s true species name ‘‘Melongena’’ is an ancient name for eggplant in Sanskrit (Spurling, 2003). The color, size, and shape of the eggplant fruit vary significantly with the variety of cultivar. Eggplant is one of the most common vegetables that is grown and consumed all around the world (Nisha et al. 2009). Thomas Jefferson introduced eggplant to the United States in 1806. Even today, a prickly, white eggplant still grows in Jefferson’s preserved Vir-ginia Garden at Monticello (Filippone et al. 2009). Eggplant fruit contains ascorbic acid and phenolics e.g chlorogenic acid, flavonoids, acetylated chlorogenic acid isomers, hydroxycinnamic acid oxides conjugates caffeic acid ,both of which are powerful antioxidants (Vinson et al. 1998). Eggplant is commonly considered as a vegetable, but botanically it is categorized as a fruit. Eggplant fruit is ranked among the top ten vegetables in terms of oxygen radical absorbance capacity due to its high phenolic content (Cao et al. 1996). A comparative study of the antioxidant capacity of different varieties was recently reported by two separate groups of researchers (Huang et al. 2004; Nisha et al. 2009). Vegetables contain several hydrophilic and lipophilic antioxidant compounds and it is important to estimate the antioxidant activity using different methods. They may act together more effectively than singly because they function synergistically and are capable of quenching free radicals in both aqueous and lipid phases (Ohr et al. 2004; Trombino et al. 2004). Antioxidant components are micronutrients present in the diet that can delay or inhibit lipid oxidation, by inhibiting the initiation or propagation of oxidizing chain reactions, and are also involved in scavenging free radicals (Othman et al., 2007). Epidemiological studies have shown that high fruit and vegetable consumption has health benefits in the prevention of chronic diseases (Cheel et al., 2007). The influence of home cooking methods (boiling , pressure-cooking , frying ) on the antioxidant activity of vegetables has been evaluated in 20 vegetables, using different antioxidant activity assays (lipoperoxyl and hydroxyl radicals scavenging and TEAC). Artichoke was the only vegetable that kept its very high scavenging-lipoperoxyl radical capacity in all the cooking methods. The highest scavenging capacity were observed in cauliflower after boiling and microwaving , in pea after boiling , and in zucchini after boiling and frying. Beetroot, green bean, and garlic kept their antioxidant activity after most cooking treatments. Swiss chard and pepper lost OH (Enez –Monreal et al. 2009). In the case of boiling or pressure-cooking occurs lixiviation phenomenon that leads to a 64% loss of total carotenoids and a 49% loss of total phenolics (Bunea et al. 2008). The phenols enter the cooking water and complex phenol proteins are found, reducing drastically by 90% or more (Barroga et al. 1985: Rocha et al. 2007). Eggplant is one of most common vegetables consumed all around the world. The present study will evaluate the antioxidant potential of two different varieties of eggplant (long purple coloured big size, and rounded purple coloured small size) in terms of total phenolic content (TPC), 2,2,di-phenyl-2-picrylhydrazyl (DPPH), superoxide radical scavenging activity, and total anthocyanin content. Extracts from purple colour small size eggplant demonstrated better antioxidant activities than the other samples which may be attributed to the higher phenolic and anthocyanin content since a linear relation was observed between the TPC and the antioxidant parameters (Nisha et al. 2009). There is comparison of among vegetables regarding to their antioxident capacity.


Tab.1.1: Comparison of different vegetables with respect to their antioxidant capacity
Vegetables Size Total antioxidant capacity
Russet potato 1 whole 4,649
Artichoke Half cup 4,402
Small red bean Half cup 13,727
Eggplant 1 whole 4,035
Red kidney beans Half cup 6,000
In the present study , the focus is on the amount of the antioxidants in eggplant after the application of different heat treatments. As eggplant is good source of antioxidants, it has been observed from different studies that heat leaves adverse effect on nutritional status of fruits and vegetables. Pakistan is one of the countries who has good cultivation rate of eggplant.
One hundered gram of fruit contains 0.7mg iron, 13.0mg sodium, 213.0mg potassium, 12.0mg calcium, 26.0mg phosphorus, 5.0mg ascorbic acid and provides 25.0 calories (Yousafi et al.2013).
In world production ranking, Pakistan is at 20th position in the eggplant production. Pakistan produces 87,000 tons eggplant every year. Moreover, it has 0.2% sharing in world wide eggplant production. It is cultivated in 9,044 ha on the land of Pakistan (FAO, 2012).
Hydrogen Peroxide is one of the most powerful oxidizers known -- stronger than chlorine, chlorine dioxide, and potassium permanganate. And through catalysis, (H2O2) can be converted into hydroxyl radicals (.OH) with reactivity second only to fluorine.
Hydrogen Peroxide (H2O2) is a colourless liquid that resembles water in many respects. Its physical properties are very similar to those of water, except that it is 40% denser. The main difference between hydrogen peroxide and water, however, is in its chemical behaviour. The single bond between the two oxygen atoms is weak, so that H2O2 readily fragments into either H and HO2 or two OHs. Either way, the resulting species are free radicals, which means they are very reactive, and this makes H2O2 a very powerful oxidizing agent. For this reason it has been utilized in rocket propulsion, when it is used to oxidise the hydrazine fuel, liberating hot gases (steam and oxygen) which propel the rocket forward. When something acts as an oxidising agent is gains electrons (removing them from the oxidised species) (Ganie et al., 2009).
For this purpose, this study has been designed to find out the appropriate method to cook eggplant at domestic level, so that maximum level of antioxidants could be obtained in our food, because antioxidants play a very important role in prevention of many chronic diseases. So, four different cooking methods i.e, grilling, cooking under pressure, boiling and deep frying has been selected for this study because these cooking methods are applied frequently at domestic level.