Date of Award

Spring 5-2021

Document Type


Degree Name

Master of Science (MS)


Food Science

First Advisor

Dr. Lilian Were

Second Advisor

Dr. Anuradha Prakash

Third Advisor

Dr. Aftab Ahmed

Fourth Advisor

Gemma Velayos


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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Creative Commons License
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