Chemical and biochemical changes during wheat seeds ageing

Proučavanje kemijskih i biokemijskih promjena koje se dešavaju u zrnu pšenica tijekom 360 dana starenja pri različitim uvjetima pokazuje da starenjem zrna dolazi do peroksidacije lipida, neenzimske glikozilacije proteina, te sniženja aktivnosti proteolitičkih i oksidoreduktivnih enzima, što se odražava na sniženje klijavosti zrna i promjenu pokazatelja tehnološke kakvoće zrna i produkata njegove meljave. Brzine i intenziteti promjena pokazuju se ovisni o primjenjenim uvjetima što upućuje na postojanje barem dva različita mehanizma starenja zrna. Gvajacilna peroksidaza i broj padanja ističu se kao potencijalni biljezi kratkotrajne starosti zrna. Analizom zrna pšenice zaraženih žitnim žiškom ustanovljeno je da kao potencijalni biljezi zaraze zrna mogu poslužiti hektolitarska masa zrna, stupanj kiselosti brašna, te aktivnosti karboksipeptidaze II, katalaze i polifenol oksidaze.Occurrence of chemical and biochemical changes during wheat seeds ageing under different storage conditions were studied. It was shown that wheat seed ageing was accompanied by lipid peroxidation, non-enzymatic glycosylation, oxidoreductase and peptidase activity loss. Combined effect of these changes caused lower seed viability (germination) as well as wheat seeds and flour quality parameters changes. Velocities and intensities of all observed changes were highly dependent on applied ageing conditions, which indicated the existence of at least two different ageing mechanisms. Potential markers for prediction of short-term wheat seed age could be guaiacol peroxidase and falling number. Analysis of wheat seeds infected by granary weevil indicated hectolitre mass, flour acidity as well as carboxypeptidase II, catalase and polyphenol oxidase as potential markers of seed infestation