Presentation Details
| Salivary Proteins in Bitterness Perception in Humans Yashmita Grover1, John N.Coupland1, John E.Hayes1, 2, Neela H.Yennawar3. 1Department of Food Science, The Pennsylvania State University, University Park, PA, USA.2Sensory Evaluation Center, The Pennsylvania State University, University Park, PA, USA.3Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA |
Abstract
Bitterness is an aversive taste that can limit the acceptance of nutritionally beneficial foods like vegetables. Its perception begins with the dissolution of bitterants in saliva before they can activate taste receptors. Saliva is composed of water, ions, and critically, proteins, which may interact with bitterants in the oral cavity. Salivary proteins could influence taste by interacting with either taste receptors or chemical stimuli; to date, most evidence comes from animal studies, leaving the contribution of salivary proteins to bitterness perception in humans incompletely understood. Here, we explored binding interactions between human salivary proteins and quinine as a step toward understanding their potential role in bitterness perception. Saliva from 46 healthy volunteers was pooled and separated (3 kDa filter) into low and high molecular weight protein fractions. Protein-unbound quinine was quantified in whole and fractionated saliva using fluorescence spectroscopy, and binding was further characterized using isothermal titration calorimetry and analytical ultracentrifugation. The proportion of unbound quinine decreased with increasing protein concentration (to 59% at 0.6 mg/mL protein). Salivary proteins showed higher binding coefficient and reaction enthalpy, binding quinine comparably at 4.3X lower protein concentration than sodium caseinate, a food-grade protein previously studied by our team. Low molecular weight salivary proteins and peptides were particularly active, displaying the highest binding coefficient and enthalpy. This was further supported by the presence of protein-quinine complexes at higher sedimentation coefficients. This study demonstrates that human salivary proteins bind quinine, providing a foundation for future research into their role in bitterness perception.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.
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