@article{neta_johanningsmeier_drake_mcfeeters_2009, title={Effects of pH Adjustment and Sodium Ions on Sour Taste Intensity of Organic Acids}, volume={74}, ISSN={["1750-3841"]}, DOI={10.1111/j.1750-3841.2009.01127.x}, abstractNote={Protonated organic acid species have been shown to be the primary stimuli responsible for sour taste of organic acids. However, we have observed that sour taste may be modulated when the pH of acid solutions is raised using sodium hydroxide. Objectives were to evaluate the effect of pH adjustment on sour taste of equimolar protonated organic acid solutions and to investigate the potential roles of organic anions and sodium ions on sour taste perception. Despite equal concentrations of protonated acid species, sour taste intensity decreased significantly with increased pH for acetic, lactic, malic, and citric acids (P < 0.05). Total organic anion concentration did not explain the suppression of sour taste in solutions containing a blend of 3 organic acids with constant concentration of protonated organic acid species and hydrogen ions and variable organic anion concentrations (R(2)= 0.480, P = 0.12). Sour taste suppression in these solutions seemed to be more closely related to sodium ions added in the form of NaOH (R(2)= 0.861, P = 0.007). Addition of 20 mM NaCl to acid solutions resulted in significant suppression of sour taste (P = 0.016). However, sour taste did not decrease with further addition of NaCl up to 80 mM. Presence of sodium ions was clearly shown to decrease sour taste of organic acid solutions. Nonetheless, suppression of sour taste in pH adjusted single acid solutions was greater than what would be expected based on the sodium ion concentration alone, indicating an additional suppression mechanism may be involved.}, number={4}, journal={JOURNAL OF FOOD SCIENCE}, author={Neta, E. R. D. and Johanningsmeier, S. D. and Drake, M. A. and McFeeters, R. F.}, year={2009}, month={May}, pages={S165–S169} }
 @article{neta_miracle_sanders_drake_2008, title={Characterization of Alkylmethoxypyrazines Contributing to Earthy/Bell Pepper Flavor in Farmstead Cheddar Cheese}, volume={73}, ISSN={["1750-3841"]}, DOI={10.1111/j.1750-3841.2008.00948.x}, abstractNote={Farmstead Cheddar cheeses with natural bandage wrappings have a distinctive flavor profile that is appealing to many consumers. An earthy/bell pepper (EBP) flavor has been previously recognized in some of these cheeses. This study characterized the alkylmethoxypyrazine compounds causing EBP flavor in Farmstead Cheddar cheeses. Eight cheeses were divided into inner, outer, rind, and wrapper sections, and tested for descriptive sensory and instrumental analyses. To assess reproducibility of EBP flavor, cheeses from the same facilities were purchased and tested after 6 and 12 mo. EBP flavor was detected in four out of 8 Farmstead Cheddar cheeses by a trained sensory panel. 2-sec-butyl-3-methoxypyrazine and 2-isopropyl-3-methoxypyrazine were identified as the main sources of EBP flavor in these cheeses by GC/O and GC/MS. In general, those alkylmethoxypyrazines were prevalent in the wrapper (106 to 730 ppb) and rind (39 to 444 ppb) sections of the cheeses. They were either not detected in inner and outer sections of the cheeses or were present at low concentrations. These results suggest that 2-sec-butyl-3-methoxypyrazine and 2-isopropyl-3-methoxypyrazine are formed near the surface of the cheeses and migrate into the cheese during ripening. Threshold values in water and whole milk were 1 and 16 ppt for 2-sec-butyl-3-methoxypyrazine, and 0.4 and 2.3 ppt for 2-isopropyl-3-methoxypyrazine, respectively. Sensory analysis of mild Cheddar cheese model systems confirmed that direct addition of those individual alkylmethoxypyrazines (0.4 to 20 ppb) resulted in EBP flavor.}, number={9}, journal={JOURNAL OF FOOD SCIENCE}, author={Neta, E. R. D. and Miracle, R. E. and Sanders, T. H. and Drake, M. A.}, year={2008}, pages={C632–C638} }
 @article{neta_johanningsmeier_drake_mcfeeters_2007, title={A chemical basis for sour taste perception of acid solutions and fresh-pack dill pickles}, volume={72}, ISSN={["1750-3841"]}, DOI={10.1111/j.1750-3841.2007.00400.x}, abstractNote={Sour taste is influenced by pH and acids present in foods. It is not currently possible, however, to accurately predict and modify sour taste intensity in foods containing organic acids. The objective of this study was to investigate the roles of protonated (undissociated) organic acid species and hydrogen ions in evoking sour taste. Sour taste intensity increased linearly with hydrogen ion concentration (R(2)= 0.995), and with the concentration of protonated organic acid species at pH 3.5 (R(2)= 0.884), 4.0 (R(2)= 0.929), and 4.5 (R(2)= 0.975). The structures of organic acid molecules did not affect sour taste after adjusting for the effects of protonated organic acid species and hydrogen ions. Sour taste intensity was also linearly related to the total concentration of protonated organic acid species in fresh-pack dill pickles (R(2)= 0.957). This study showed that the sour taste of organic acids was directly related to the number of molecules with at least 1 protonated carboxyl group plus the hydrogen ions in solution. Conclusions from these results are that all protonated organic acids are equally sour on a molar basis, that all protonated species of a given organic acid are equally sour, and that hydrogen ions and protonated organic acids are approximately equal in sour taste on a molar basis. This study provides a new understanding of the chemical species that are able to elicit sour taste and reveals a basis for predicting sour taste intensity in the formulation of acidified foods.}, number={6}, journal={JOURNAL OF FOOD SCIENCE}, author={Neta, E. R. Da Concetcao and Johanningsmeier, S. D. and Drake, M. A. and McFeeters, R. F.}, year={2007}, month={Aug}, pages={S352–S359} }
 @misc{neta_johanningsmeier_mcfeeters_2007, title={The chemistry and physiology of sour taste - A review}, volume={72}, ISSN={["1750-3841"]}, DOI={10.1111/j.1750-3841.2007.00282.x}, abstractNote={Sour taste is the key element in the flavor profile of food acidulants. Understanding the chemistry and physiology of sour taste is critical for efficient control of flavor in the formulation of acid and acidified foods. After a brief introduction to the main applications of food acidulants, several chemical parameters associated with sour taste are discussed. Special emphasis is given to hydrogen ions, protonated (undissociated) acid species, titratable acidity, anions, molar concentration, and physical and chemical properties of organic acids. This article also presents an overview of the physiology of sour taste and proposed theories for the transduction mechanisms for sour taste. The physiology of sour taste perception remains controversial and significant diversity exists among species with regard to cellular schemes used for detection of stimuli. The variety of mechanisms proposed, even within individual species, highlights the complexity of elucidating sour taste transduction. However, recent evidence suggests that at least one specific sour taste receptor protein has been identified.}, number={2}, journal={JOURNAL OF FOOD SCIENCE}, author={Neta, Edith Ramos Da Conceicao and Johanningsmeier, Suzanne D. and McFeeters, Roger F.}, year={2007}, month={Mar}, pages={R33–R38} }
 @article{dougherty_ramos da conceicao neta_mcfeeters_lubkin_breidt_2006, title={Semi-mechanistic partial buffer approach to modeling pH, the buffer properties, and the distribution of ionic species in complex solutions}, volume={54}, ISSN={["1520-5118"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000239454700045&KeyUID=WOS:000239454700045}, DOI={10.1021/jf0531508}, abstractNote={In many biological science and food processing applications, it is very important to control or modify pH. However, the complex, unknown composition of biological media and foods often limits the utility of purely theoretical approaches to modeling pH and calculating the distributions of ionizable species. This paper provides general formulas and efficient algorithms for predicting the pH, titration, ionic species concentrations, buffer capacity, and ionic strength of buffer solutions containing both defined and undefined components. A flexible, semi-mechanistic, partial buffering (SMPB) approach is presented that uses local polynomial regression to model the buffering influence of complex or undefined components in a solution, while identified components of known concentration are modeled using expressions based on extensions of the standard acid-base theory. The SMPB method is implemented in a freeware package, (pH)Tools, for use with Matlab. We validated the predictive accuracy of these methods by using strong acid titrations of cucumber slurries to predict the amount of a weak acid required to adjust pH to selected target values.}, number={16}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Dougherty, Daniel P. and Ramos Da Conceicao Neta, Edith and McFeeters, Roger F. and Lubkin, Sharon R. and Breidt, Frederick, Jr.}, year={2006}, month={Aug}, pages={6021–6029} }