Date of Award
Master of Science (MS)
Dr. Lilian Were
Dr. Anuradha Prakash
Dr. Aftab Ahmed
Sunflower protein can be extracted at alkaline pH with sulfites or organic solvent de-phenolization of sunflower seed meals if greening is unwanted. This greening is promoted at alkaline pH when chlorogenic acid (CGA) oxidizes and reacts with free amine groups from amino acids, such as lysine. Thiol-containing dough conditioners: L-cysteine hydrochloride and reduced glutathione (GSH) were investigated as an alternative de-greening strategy to de-phenolization. Varying pH from 7 to 11 and concentration of 0.82 to 5.6 mM were randomly assigned by Response Surface Methodology (RSM) to evaluate the combined and additive greening inhibition effect of thiol and extraction pH. The powders with the highest greening were control (pH 8.93-9.3 and no added thiols) and pH 10.41 with 0.82 mM with thiols added. The powders with cysteine however had more browning than GSH. From RSM, the maximum greening inhibition was achieved with pH 8.71 and 4.23 mM cysteine and pH 8.51 and 3.78 mM GSH. Furthermore, fluorescence spectroscopy revealed that cysteine had a protective effect against alkaline denaturation, whereas GSH quenched fluorescence. Overall, the incorporation of thiol ingredients can be an alternative de-greening strategy for sunflower protein. These results could lead to extensive use of sunflower protein applications in non-allergenic and non-GMO plant-based meat alternatives or bakery products where greening is unwanted.
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Ishii, A.K. (2021). Color and structural modifications of alkaline extracted sunflower protein concentrates and isolates using L-cysteine and glutathione. Master's thesis, Chapman University. https://doi.org/10.36837/chapman.000228