Valorization of olive oil extraction by-products through functional breadmaking

Agri-food industry is facing a major problem from the issuing of enormous quantities of wastes also known as by-products. The olive oil industry generates yearly tons of such byproducts among which, olive pomace (OP) is the most important one. OP has a negative effect on the environment, due to its high salinity and acidity, yet it is rich in fibers, polyphenols, proteins, and many other functional compounds, and can serve as a healthy functional ingredient, if incorporated into food. The consumer’s awareness about health is increasing, and is more interested in consuming healthier products. Bread is one of the most consumed staple foods, but it is associated with several diseases. Thus, the incorporation of OP into bread would reduce its disposal, and exploit its health benefits on the human body. OP of two Sardinian cultivars, Bosana and Semidana, underwent freeze-drying and grounding, and substituted wheat flour at 1%, 2%, and 3% (w/w) in the bread formula. OP’s proximate composition proved its importance due to the prominent polyphenols, fibers, macro and micronutrients content. Upon its incorporation into bread dough, the latter was studied for its rheological parameters, pasting profile, and dough fermentation. The parameters showed significant differences between formulae compared to the control not containing any OP. Doughs fortified with 1% Bosana, 1% and 2% Semidana showed improvements in the stability, viscoelastic properties, elasticity, stickiness, water absorption, probably due to the presence of fibers and polyphenols. Higher levels of OP substitution negatively affected the above-cited parameters, due to the dilution of the gluten content and the resulting disruption of the gluten-starch matrix which weakens the dough’s structure. Bread loaves, on the other hand, showed improvements in the antioxidant activity, and nutritional quality with increasing OP levels. Technological parameters were significantly worsened, especially at levels equal to or higher than 2%, decreasing specific volume, hardening and darkening of the crumb, cell porosity, and enhancing bread staling. Substitution levels of 1% did not show, for most parameters, any differences from the control. Among samples, breads fortified with 1% OP of both cultivars were the most liked by consumers; however, they had an appealing tendency and a higher acceptance for that fortified with 1% Bosana’s OP. In conclusion, the substitution of wheat flour with 1% OP powder serves as the optimal formulation for an optimal combination of all quality factors. Keywords: bread, by-products, fortification, functional food, olive pomace.

Agri-food industry is facing a major problem from the issuing of enormous quantities of wastes also known as by-products. The olive oil industry generates yearly tons of such byproducts among which, olive pomace (OP) is the most important one. OP has a negative effect on the environment, due to its high salinity and acidity, yet it is rich in fibers, polyphenols, proteins, and many other functional compounds, and can serve as a healthy functional ingredient, if incorporated into food. The consumer’s awareness about health is increasing, and is more interested in consuming healthier products. Bread is one of the most consumed staple foods, but it is associated with several diseases. Thus, the incorporation of OP into bread would reduce its disposal, and exploit its health benefits on the human body. OP of two Sardinian cultivars, Bosana and Semidana, underwent freeze-drying and grounding, and substituted wheat flour at 1%, 2%, and 3% (w/w) in the bread formula. OP’s proximate composition proved its importance due to the prominent polyphenols, fibers, macro and micronutrients content. Upon its incorporation into bread dough, the latter was studied for its rheological parameters, pasting profile, and dough fermentation. The parameters showed significant differences between formulae compared to the control not containing any OP. Doughs fortified with 1% Bosana, 1% and 2% Semidana showed improvements in the stability, viscoelastic properties, elasticity, stickiness, water absorption, probably due to the presence of fibers and polyphenols. Higher levels of OP substitution negatively affected the above-cited parameters, due to the dilution of the gluten content and the resulting disruption of the gluten-starch matrix which weakens the dough’s structure. Bread loaves, on the other hand, showed improvements in the antioxidant activity, and nutritional quality with increasing OP levels. Technological parameters were significantly worsened, especially at levels equal to or higher than 2%, decreasing specific volume, hardening and darkening of the crumb, cell porosity, and enhancing bread staling. Substitution levels of 1% did not show, for most parameters, any differences from the control. Among samples, breads fortified with 1% OP of both cultivars were the most liked by consumers; however, they had an appealing tendency and a higher acceptance for that fortified with 1% Bosana’s OP