One of the genotypes of pea (Pisum sativum L.) with purple flowers and pods is called Tutankhamun’s pea in Japan. The immature fresh peas change their color from green to brownish red during thermal cooking. In addition, compared to the fresh peas of normal cultivar, fresh peas of the purple cultivar possess higher antioxidant activity. In this study we isolated a polyphenol, which acts as the antioxidant compound, from fresh seed coat of the purple cultivar and evaluated the effect of cooking on its antioxidant activity. The peas were cooked using two different methods: boiling or simmering in water. The cooked peas were freeze-dried and ground to powder in a mill. The extracts of the powder were obtained using acetone-water-acetic acid (AWA). The antioxidant activity and total phenolic content of the peas were compared with those of the raw pea by DPPH radical scavenging assay and folin-ciocalteu method, respectively. In addition, the amounts of antioxidant compound concentrated by solid phase extraction were analyzed using HPLC equipped with an Atlantis T3 column. The antioxidant activity of the peas was significantly reduced upon boiling; however, there was no difference in antioxidant activity when the peas were allowed to simmer until they completely absorbed the broth. Total phenolic content of the pea of purple cultivar also dramatically decreased upon boiling, but simmering did not cause any significant loss of phenolic content. These results suggest that the antioxidant activity of the peas is retained even after cooking by simmering, likely owing to the presence of a derivative of the antioxidant compound, whereas the active compound is water-soluble and is lost to hot water during boiling. Therefore, this study suggests that it is important to avoid loss of the antioxidant compound of Tutankhamun’s peas during cooking.

Effect of cooking on antioxidant activity of the pea (Pisum sativum L.) cultivar with purple pods

256th National Meeting (2018)

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