Abstract
Tomato (Lycopersicon esculentum) is one of the rich sources of antioxidants, mainly, lycopene which is known to be associated with decreased risks of chronic diseases. However, cooking influences the antioxidant properties of vegetables. Therefore, this study aimed to determine the effect of three cooking methods on the antioxidant properties of tomato. The conditions of the cooking methods of tomato were boiling at 100 oC for 6 min, microwave cooking at 560W for 40 sec and stir-frying at 230 oC for 4.5 min. Ethanol (70 %, v/v) was used to extract the antioxidant properties (such as phenolics, flavonoid and other antioxidant compounds) of tomato. These antioxidant properties were determined by using total phenolic content (TPC), total flavonoid content (TFC), antioxidant capacity and DPPH radical scavenging activity analysis. Results indicated that cooking has significant influences on the antioxidant properties of tomato. Boiling did not have significant changes in the TPC, however microwave cooking and stir-frying caused significant losses compared to fresh tomato. Stir-fried tomato had significantly the lowest TPC. All three cooking methods caused significant losses in TFC, however the losses are less significant during boiling compared to microwave cooking and stir-frying. Significantly higher antioxidant capacity was observed in microwave cooked tomato than fresh and other cooked tomatoes. The highest antioxidant activity was observed in microwave cooked tomato followed by stir-fried and fresh tomatoes.
Highlights
In the past few decades, there has been increasing interest in the use of dietary antioxidants from plant sources in order to reduce the risk of developing degenerative diseases such as cancer, cardiovascular disease and immune dysfunction (Chun et al, 2005)
The present study has determined the effect of three different cooking methods such as boiling, microwave cooking and stir-frying on the antioxidant properties of tomato
The result of total phenolic content (TPC) of tomato is in line with the values reported by Luthria et al (2006), Natella et al (2010) and Borguini et al (2013)
Summary
In the past few decades, there has been increasing interest in the use of dietary antioxidants from plant sources in order to reduce the risk of developing degenerative diseases such as cancer, cardiovascular disease and immune dysfunction (Chun et al, 2005). Antioxidants play a crucial role in maintaining human health by inhibiting or delaying free radical damage in the body. Antioxidants can be defined as any molecule capable of stabilizing or deactivating free radicals before they attack cells (Rahman, 2007). Free radicals carry an unpaired electron that is looking to pair up with another. Free radicals can cause oxidative damage to cell components such as proteins, DNA and lipids which leads to increase the risk of degenerative diseases (Rezaeizadeh et al, 2011). An antioxidant encounters a free radical by freely gives up an electron of its own which satisfies the free radical and inhibits the cellular damage (Huy et al, 2008)
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