Olive leaf extract and butylated hydroxytoluene as antioxidants in refined versus whole wheat flour crackers: a physico-chemical characterization

BACKGROUND
This study investigated the physico-chemical properties of four cracker samples formulated with refined (RF) or whole wheat flour (WF), and enriched with olive leaf extract in either free form (OLE) or encapsulated form (MCR), as well as with butylated hydroxytoluene (BHT) antioxidant, in comparison with non-enriched control samples (CTR).

RESULTS
The MCR sample showed the highest total antioxidant capacity. Free OLE showed an intermediate value among all the tested samples and OLE reduced the peroxide value significantly in comparison with CTR. Encapsulated OLE was similar to the other formulations. The WF crackers showed lower moisture content, softer texture, and a lower impact of the natural antioxidant on color the parameters than the RF samples. The antioxidant type displayed little impact on the physical properties of crackers, with MCR showing the highest moisture content and texture consistency, and free OLE was comparable to CTR and BHT. Although free OLE revealed the greatest impact on the crackers' color, encapsulation significantly reduced this effect. Significant changes in proton nuclear magnetic resonance (1H NMR) parameters were mainly associated with the higher fiber and lower gluten content of WF in comparison with RF; the type of antioxidant used affected the size of its impact.

CONCLUSIONS
The results revealed the potential of encapsulated OLE as a natural antioxidant for the development of clean label snacks. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.