Walnut Male Flowers (Juglans regia L.) as a Functional Addition to Wheat Bread

Abstract

The aim of this study is to assess the effect of adding dried and ground walnut male flowers to wheat flour on selected physicochemical and antioxidant properties of the obtained wheat bread. The control sample was bread without the addition of walnut male flowers. In the tests, the addition of flowers was used in the amounts of 0.5%, 1.0%, 1.5%, 2.0% and 2.5% of the weight of the flour used in the control sample. Bread dough was prepared according to the direct method with the use of yeast. The parameters of the baking process of the control bread and of the test bread were calculated. The selected parameters determining the quality of the obtained bread, including the loaf volume, the specific volume, the crumb porosity, the crumb texture and the color were measured. The antioxidant potential and total polyphenol content were tested both in the dough and in the bread. The test results were analyzed statistically. It was found that the partial replacement of wheat flour with walnut male flowers resulted in a significant reduction in the loaves' volume and in the darkening of both the color of the dough and the crumb. The value of the L* parameter decreased with the increasing addition of walnut flowers. The lowest values of this parameter were found to be 53.87 (crust) and 39.94 (crumb) in the sample with 2.5% addition. The average volume of the loaves ranged from 565 cm³ (0.5%) to 675 cm³ (control). The use of the additive in the amount of 2.5% caused significant changes in the values of most of the examined parameters of the bread crumb texture. The addition of walnut male flowers to the flour had a significant effect on the antioxidant potential and the total polyphenol content of the tested doughs and breads. In the case of bread, the total polyphenol content value ranged from 96.90 mg GAE/g dw to 208.08 mg GAE/g dw. Similarly, the antioxidant potential increased with increasing walnut male flower supplementation. The antioxidant potential determined by the ABTS and FRAP methods ranged from 1.42 mmol TE/g dw to 2.02 mmol TE/g dw and from 0.08 mmol TE/g dw to 0.33 mmol TE/g dw, respectively. The obtained research results prove the application potential of walnut flowers in the design of food, with beneficial pro-health properties, and are an example of the use of plant by-products in the process of food enrichment.

Keywords: J. regia; antioxidant activity; flowers; functional food; total polyphenol; wheat bread.