Effect of additives and food processing conditions on Benzyl glucosinolate hydrolysis products in Carica papaya

Gayathri Nagappan (2012) Effect of additives and food processing conditions on Benzyl glucosinolate hydrolysis products in Carica papaya. Masters thesis, Universiti Malaysia Sabah.

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Abstract

Glucosinolate are sulphur-containing secondary metabolites found largely in Brassicaceae family. Glucosinolate undergoes hydrolysis readily upon cell rupture, such as cutting and cooking, by the naturally-occurring enzyme myrosinase to form mainly isothiocyanates and/or simple nitriles. Isothiocyanates are known to possess anticarcinogenic properties while nitriles are largely inactive. Benzyl isothiocyanate, a hydrolysis product of benzyl glucosinolate, is one of the most potent anticancer agents. However, formation of benzyl isothiocyanate is depending upon reaction conditions where benzyl nitrile is formed at the expense of benzyl isothiocyanate. Thus, the potential health benefits of benzyl isothiocyanate may be surpassed by the ineffective benzyl nitrile. In this study, the factors influencing the formation of benzyl isothiocyanate were investigated to understand further the benzyl glucosinolate hydrolysis pathway in different parts of papaya (Carica papaya). The results showed that the concentration (dry weight), of benzyl isothiocyanate was found greater in papaya leaf with 349 μM followed by 24 μM in unripe fruit and 12 μM in flower. The highest amount of benzyl isothiocyanate produced was observed at room temperature (25oC) where it decreases gradually as the temperature increases up to 80oC. Comparing three common domestic methods of cooking vegetable i.e. blanching, boiling and slow heating, the results show that the high temperature treatment produced mainly benzyl nitrile; while slow heating up to 40oC produced more benzyl isothiocyanate. Both hydrolysis products were found largely leached into the cooking liquid (soup). The production of benzyl isothiocyanate was optimum at pH 6 – 7. Meanwhile, the addition of both ferrous and ferric ions (0 – 10 mM) favors the formation of benzyl nitrile. Conveniently, adding an iron-chelating agent, EDTA, has shown an increasing trend in the formation of benzyl isothiocyanate. A small amount of ascorbic acid enhanced the formation of benzyl isothiocyanate, however, higher concentration inhibits its production. Overall, this work has shown that to ensure an optimum uptake of this beneficial compound from papaya leaf, unripe fruit or flower consumption, food preparation practices have to be favoring the formation of benzyl isothiocyanate.

Item Type:	Thesis (Masters)
Keyword:	Glucosinolate, Myrosinase, Benzyl isothiocyanate, Benzyl nitrile, Isothiocyanates, Papaya
Subjects:	Q Science > QK Botany > QK1-989 Botany > QK710-899 Plant physiology
Department:	SCHOOL > School of Science and Technology
Depositing User:	DG MASNIAH AHMAD -
Date Deposited:	18 Dec 2024 15:27
Last Modified:	18 Dec 2024 15:27
URI:	https://eprints.ums.edu.my/id/eprint/42323

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