Evaluating the effects of lactic acid bacteria and olive leaf extract on the quality of gluten-free bread

Abstract

Celiac disease is an autoimmune intestinal disease which usually occurs in susceptible individuals. This digestive disease damages the villi of the small intestine and impairs absorption of nutrients. Patients with celiac disease, cannot tolerate the gluten protein in the bread, and therefore, alternatives should be taken into consideration to improve the quality of gluten-free bread.In this study, the possibility of producing gluten-free bread with high quality and nutritional values, using corn-based and rice-based sourdough inoculated with Lactobacillus plantarum (ATCC 14917) and Lactobacillus fermentum (ATCC 9338) as starter cultures was investigated. In addition, the addition of 5% and 10% olive leaf extract using the encapsulation method was evaluated. Physicochemical properties of the prepared gluten-free bread, including moisture content, pH, Total Titratable Acidity (TTA), texture, and total acceptability of the bread based on odor, firmness, taste, chewability, and staleness were evaluated. Antifungal properties of the prepared breads were also determined. Each evaluation was performed in triplicates and the results were statistically analyzed using generalized linear model (GLM) by SPSS. Means were compared with Duncan's multiple range test at 95% Confidence Interval.According to the results, L. plantarum significantly decreased the pH values of the samples (p < .01). Also, sourdoughs prepared with L. plantarum showed a significantly higher TTA compared to those prepared with L. fermentum (p < .01). Breads in which olive leaf extract and lactic-acid bacteria (LAB) were used showed the highest moisture content (p < .01). Also, considering the sensory evaluation of the bread, the acceptability of the gluten-free bread increased with the increased levels of sourdough and olive leaf extract. Generally, the use of LAB-inoculated sourdough and olive leaf extract can improve the quality of the bread in regards to the taste, staleness, odor, chewability, softness, moisture content, pH, acidity and texture. Also, they can improve the antifungal properties of the bread, thereby increasing their shelf-life. Therefore, these ingredients as alternatives to gluten may be employed for improving the structure and acceptability of the gluten-free bread.