THE PHENOLIC COMPOUNDS EVOLUTION IN A DURUM WHEAT CULTIVAR DURING STORAGE
AT DIFFERENT TEMPERATURES

M. Avrămiuc

Abstract
    The aim of this work was to investigate the influence of storage temperature and time on Total Phenolic Content (TPC) in a romanian durum wheat cultivar. The biological material was represented by fall durum wheat grains from which there were formed control and working samples (grains, flour and bran). The control samples were stored at 10°C, and the working ones at four thermal thresholds (40°C, 60°C, 120°C and 180°C) for 5 days. After 1, 3 and 5 days it has estimated Total Phenolic Content (TPC) through a colorimetric assay, by measuring the ability of phenols to reduce Folin-Ciocalteu reagent. In all analyzed samples, compared to controls (samples stored at 10°C), the largest decreases of Total Phenolic Content were after 5 days of storage, with significant percentage reductions at 180°C and 120°C, in flour type 480 (WF), and in whole-wheat flour (WWF). After 1 and 3 days of storage, significant percentage reductions of TPC were only in flour type 480 samples stored at 180°C and 120°C too. Keeping of durum wheat samples under high temperature as flour caused a greater reduction in the total content of phenolic compounds, compared to grains or bran.

Key words: wheat, flour, bran, phenolic content

EVOLUŢIA COMPUŞILOR FENOLICI LA UN SOI DE GRÂU DUR ÎN TIMPUL PĂSTRĂRII LA DIFERITE TEMPERATURI

M. Avrămiuc

Rezumat
    Scopul acestei lucrări a fost de a cerceta influenţa temperaturii şi a timpului de păstrare asupra conţinutului total de compuşi fenolici dintr-un cultivar românesc de grâu dur. Materialul biologic a fost reprezentat de boabe de grâu dur de toamnă din care s-au constituit probe de control şi de lucru (boabe întregi, făină şi tărâţe). Probele de control au fost stocate la +10°C, iar cele de lucru la 4 praguri termice diferite (+40°C, +60°C, +120°C şi +180°C) pentru 5 zile. După 1, 3 şi 5 zile s-a determinat Conţinutul total fenolic (TPC) printr-o metodă colorimetrică, prin măsurarea capacităţii fenolilor de a reduce reactivul Folin-Ciocalteu. La toate probele analizate, comparativ cu cele de control (păstrate la 10°C), cele mai mari reduceri ale Conţinutului total fenolic au fost după 5 zile de păstrare, cu reduceri procentuale semnificative la 180°C şi 120°C, la făina tip 480 (WF) şi la făina obţinută din bobul întreg (WWF). După 1 şi 3 zile de păstrare, reduceri procentuale semnificative ale TPC au fost doar la probele de făină tip 480 păstrate tot la 180°C şi 120°C. Menţinerea probelor de grâu dur la temperaturi ridicate sub formă de făină a cauzat o reducere mai mare a conţinutului total de fenoli, comparativ cu probele păstrate sub formă de boabe sau tărâţe.

Cuvinte cheie: grâu, făină, tărâţe, conţinut fenolic