engleski

Loss of oxidoreductase activities during ageing of wheat seeds

Seed ageing is a natural, time-dependent process starting with harvest and continuing over storage period. During this process free radical generation/oxidation and non-enzymatic glycosylation within seeds occur causing molecular damage and loss of enzymatic activity. Endogenous cereal oxidoreductases play important role in production technologies, while the loos of activity of these enzymes could affect the quality of final bakery products. In this research oxidoreductive enzymes activity changes were monitored during ageing of wheat seeds, as well as possible causes of enzymatic activity changes - lipid peroxidation products and advanced glycosylation end products. Wheat seeds of cultivars Divana, Žitarka and Srpanjka, were aged during one year at four different storage conditions: (1) 4 ± 0.5 °C ; 45 ± 4 % RH ; (2) 25 ± 0.7 °C ; 45 ± 7 % ; (3) 40 ± 0.6 °C ; 45 ± 2 % RH ; and (4) warehouse conditions fluctuating from 2-25 °C and 60-74 % RH due to environmental climate changes. Samples were analyzed monthly for activities of glutathione reductase - GR, catalase - CAT, guaiacol peroxidase - POX, polyphenol oxidase - PPO and lypooxigenase - LOX), and amount of lipid peroxidation products (LPO) and advanced glycosylation end products (AGE). The results showed that ageing of wheat seeds was accompanied by loss of oxidoreductase activities as follows: POX > PPO > LOX > CAT > GR. High correlation between enzyme activity loss and accumulation of advanced glycosylation end products indicates that loss of enzyme activities could be attributed to the inactivation by non-enzymatic glycosylation.

ageing; wheat; oxidoreductases; non-enzymatic glycosylation

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