Investigation on the Effect of Green Tea Hydroalcoholic Extract on the Dough Rheological Properties and Staling of Barbari Bread

Staling is one of the main causes of reduced bread shelf life. In this study, the effect of using green tea hydroalcoholic extract as a beneficial herbal compound on dough rheological properties and staling of barbari bread was investigated.

In order to prepare the hydroalcoholic extract, first, green tea was extracted with 30% ethanol and then concentrated and powdered by spray dryer. The product was subjected to qualitative analysis and then was added at the 0, 0.5, 1.5, 2.5 and 3.5% concentrations (based on flour weight) in the formulation of consumable dough followed by performing the dough rheological properties and bread quality tests, staling, bread crumb hardness (by TPA device) and the samples thermal properties (by DSC device) were evaluated in one, three and five days after cooking.  

The results of dough rheological tests showed that the green tea hydroalcoholic extract increased flour quality and improved the dough rheological properties and also, increased the moisture and total polyphenol contents in bread, at all concentrations. In all three time periods, 0.5 and 1.5% treatments had the highest soft tissue as compared to other treatments and the control samples. The results of thermal properties indicated that 1.5% treatment reduced the starch retrogradation in the short- term (one day after baking) and possibly long-term (more than five days after baking).

In this study, green tea hydroalcoholic extract acts as an oxidizing improver and improved the dough rheological properties, and also, 0.5 and 1.5% treatments had the most effect on reduces the bread crumb hardness by delaying the staling of barbari bread.