The influence of natural oils of blackcurrant, black cumin seed, thyme and wheat germ on dough and bread technological and microbiological quality

Plant oils have potential as antimicrobial ingredients in bread. However, they may influence bread production. This study compares the influence of blackcurrant (BC), cumin seed (CS), thyme (TH) and wheat germ (WG) oil on the technological quality of dough/bread, as well as their antifungal activity. The influence of the oils was tested on the water absorption and kneading properties of dough, elasticity, starch gelatinization and yeast activity and were compared with a control without oil and a reference with calcium propionate. Bread weight, volume, color and crumb texture were evaluated. The antifungal activity was tested through a shelf-life test of breads. Results showed that, generally, the addition of oils resulted in a decrease of dough consistency. WG showed the highest overall resemblance with the control concerning water absorption and kneading properties of the dough. Additionally, WG and TH were the only oils that could extend the shelf-life. WG caused a shelf-life increase of 3 days (+ 33%), TH 20 days (+100%). However, TH had a negative impact on dough rheology and yeast activity due to the high presence of thymol. In conclusion, it can be stated that WG showed the most promising combined technological and microbiological benefits in dough/bread.