THE INFLUENCE OF STORAGE TEMPERATURE AND TIME ON TOTAL PHENOLIC CONTENT IN A SOFT WHEAT CULTIVAR

Abstract

The influence of storage temperature and time on Total Phenolic Content (TPC) in a soft wheat cultivar, was the purpose of this paper. The biological material was represented by soft 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  (40ºC, 60ºC, 120ºC  and  180ºC)  for  15  days.  Aftet  5,  10  and  15  days,  Total  Phenolic  Content  (TPC)  has  been estimated  by  a  colorimetric  assay,  by  measuring  the  ability  of  phenols  to  reduce  Folin-Ciocalteu reagent. In all analyzed samples, compared to controls (samples stored at 10ºC), the largest decreases of  Total  Phenolic  Content  were  registered  after  15  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 10 days of storage, significant percentage reductions of TPC were registered in flour type 480 (WF), and in  whole-wheat  flour  (WWF),  and  after  5  days  in  WF  (in  all  cases  in  samples  stored  at  180°C  and 120°C). The percentage decrease of TPC values was emphasized more when the storage temperature increased from 120°C to 180°C, compared with the thresholds 40-60°C or 60-120°C. The keeping of soft wheat samples under high temperature conditions led to a greater reduction in the total content of phenolic compounds,as compared to grains or bran.