Lowering greening of cookies made from sunflower butter using acidic ingredients and effect on reducing capacity, tryptophan and protein oxidation

Lowering of greening formed from oxidized chlorogenic acid (CGA) and amino groups, and favoured at alkaline pH, was investigated using acidic ingredients (sour cream, buttermilk, yoghurt, and honey) in sunflower butter cookies. Cookies with maple syrup added were used as a positive control. Changes in greening intensity, greening reactants (total phenols, CGA, protein), antioxidant capacity, tryptophan and Schiff base fluorescence were measured. Percentage greening, pH and aw of cookies followed the same order: maple syrup > sour cream ≥ buttermilk > yoghurt > honey. pH was positively correlated with greening intensity (r = 0.77) and negatively correlated with CGA (r = −0.96). Total phenolic content, antioxidant capacity, tryptophan and Schiff bases were similar among cookies. The results suggest it is possible to decrease greening by minimizing storage time and using acidic ingredients. Minimal greening with acidic ingredients can extend the application of sunflower butter as a baking ingredient without loss of free radical-scavenging capacity, or higher protein oxidation.