Production of bread including humic acid

In this study, the effects of humic acid (20%, v/v) addition into bread formulation at 1, 2, 3, 4, and 5% (in water basis) levels on quality parameters, staling, microbiological changes and antioxidant activity were investigated. The bread samples were evaluated in terms moisture, weight loss, volume, color (L*, a*, b*) and texture (hardness) values, microbiological analysis (total bacteria, mold-yeast), antioxidant activity (TEAC). The products were packed in plastic bags and stored at room temperature to observe mold growth on their surface. The moisture values of breads did not change too much by humic acid addition. The weight loss values of 1, 2 and 3% humic acid added breads were less than that of control bread (p<0.05). As compared to control bread, volume values of humic acid added breads increased up to 4% level, then decreased. Crumb L* (lightness) values decreased while a* (redness) increased by increasing humic acid level. Yellowness (b*) values increased up to 3% addition level, then decreased. In terms of crust color values, L* and b* reduced by increasing humic acid level, while a* increased up to 2% addition level. Although the color of the humic acid added breads were darker than that of the control sample, they were still in the acceptable range. According to texture analysis performed after 1st and 3rd days of production, the hardness values of the 1 and 2% humic acid added breads decreased as compared to control. The total aerobic bacteria and total mold-yeast acounts (log cfu/g) of humic acid added breads at 0th and 3rd days of storage reduced significantly (p>0.05) as compared to control bread. Mold growth was not seen at the surface in all breads through 3 days of storage, while started in control bread at 4th day. Molding was obsorved in all breads at 6th day of storage, however only one colony was detected at 2% humic acid added sample. Antioxidant activity of humic acid solution was found as 2928,6 mM trolox/mL and antioxidant activity increased by adding humic acid to bread. Humic acid addition into the products did not caused any adverse effects in terms of taste and odor. As a result, humic acid had a potential to use as functional ingredient in bread formulation at certain levels. Keywords: Bread, humic acid, molding, staling, antioxidant activity