The taste qualities of acidulants have not been studied in detail despite the fact that they are widely used by the food industry. Studies on characterizing the sensory properties of organic and inorganic acids are very limited. Reported studies are commonly on threshold, equi-sour and the time intensity values of sourness. A series of experiments were conducted to determine the sensory properties of selected acidulants by different sensory and multivariate methods. First, the technique of Free-Choice Profiling was applied in order to characterize the sensory profile of some selected acids (adipic, citric, fumaric, glucono-delta-lactone, hydrochloric, lactic, malic, phosphoric, quinic, succinic, tartaric, citric:fumaric, citric:malic and fumaric:malic) on a weight (0.08% w/v or v/v) basis. Results analyzed through Generalized Procrustes Analysis indicate that on a weight basis (w/v or v/v), acids differed in their flavor and taste dynamics. Likewise, acids were described differently by individual panelists. Second, the sourness power functions of the selected acidulants were generated from five molar concentrations by magnitude estimation involving 16 trained panelists. Equi-sour concentrations were determined by regressing the log of the rescaled response (sensory) on the log of the stimuli (physical). The calculated equi-sour levels ranged from 0.48 ml/L for HCl to 2.34 g/L for glucono-delta-lactone when citric add was set at 1.0 g/L. These theoretical equi-sourness were then tested by using an alternative sensory method, the directional difference from control test. Third, the sensory profile of the acidulants at their equi-sour levels was characterized using two sensory methods, free-choice profiling and the conventional descriptive analysis. The former was analyzed by Generalized Procrustes Analysis while the latter was analyzed by Principal Component Analysis. The two sensory methods gave similar patterns of information regarding the add samples. The similarities of several organic acids and their mixtures were very evident. Hydrochloric and phosphoric acids were astringent while succinic add was bitter and had a monosodium glutamate taste. It was concluded that adds had other sensory properties aside from sourness that must be considered in a given food application. / Graduation date: 1993

Response characteristics and tactile coding capacities of single neurons of the dorsal column nuclei (DCN), and the dorsal horn, in particular, neurons of the spinocervical tract (SCT), were investigated in anaesthetized cats. Purely dynamically-sensitive tactile neurons of the DCN could be divided into two classes, one associated with hair follicle afferent (HFA) input, the other with Pacinian corpuscle (PC) input. The HFA-related class was most sensitive to low-frequency (&lt50 Hz) vibration, had phaselocked responses to vibration frequencies up to ~75 Hz and had a graded response output as a function of vibrotactile intensity changes. PC-related neurons had broader vibrotactile sensitivity, extending to ~300 Hz with tightest phaselocking between 50 and 200 Hz. The SCT neurons in the lumbar dorsal horn had tactile receptive fields on the hairy skin of the hindlimb and a very limited capacity to signal, in a graded way, the intensity parameter of the vibrotactile stimulus. Furthermore, because of their inability to respond on a cycle-by-cycle pattern at vibration frequencies above 5-10 Hz, these neurons were unable to provide any useful signal of vibration frequency beyond ~5-10 Hz, in contrast to DCN neurons. In the parallel human psychophysical study, the capacity for vibrotactile frequency detection and discrimination was examined in five subjects in glabrous and hairy skin. The vibrotactile detection threshold values obtained at four standard frequencies of 20, 50, 100 and 200 Hz were markedly higher on the hairy skin than on the glabrous skin. The discrimination task was examined by means of a two-alternative, forced-choice psychophysical procedure. Measures of the discriminable frequency increment (?????) and the Weber Fraction (????? / ??), revealed similar capacities for frequency discrimination at the two different skin sites at the standard frequencies of 20, 100 and 200 Hz, but an equivocal difference at 50 Hz. Cutaneous local anaesthesia in the dorsal forearm produced a marked impairment in vibrotactile detection and discrimination at the low frequencies of 20 and 50 Hz but little effect at higher frequencies, confirming that vibrotactile detection and discrimination in hairy skin depend upon superficial receptors at low vibrotactile frequencies, but depend on deep, probably Pacinian corpuscle receptors for high frequencies.

Thesis (M.A.)--University of Toronto, 2006. / Source: Masters Abstracts International, Volume: 44-06, page: 2513. Includes bibliographical references (leaves 121-126).

Thesis (M.A.)--York University, 2006. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 70-73). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://proquest.umi.com/pqdweb?index=0&did=1240699451&SrchMode=1&sid=15&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1195058296&clientId=5220

Thesis (M. Sc.) (Hons.) -- University of Western Sydney, Hawkesbury, 1999. / Includes bibliographical references (leaves 167-186).

Thesis (Ph. D.)--University of Sydney, 2007. / Title from title screen (viewed May 1, 2007). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Kolling Institute of Medical Research. Includes bibliographical references. Also issued in print.

Thesis (Ph. D.)--Virginia Commonwealth University, 2007. / Prepared for: School of Allied Health Professions . Bibliography: leaves 96 - 114. Also available online via the Internet.

Thesis (M. Phil.)--University of Sydney, 2005. / Title from title screen (viewed 28 March 2008). Submitted in fulfilment of the requirements for the degree of Master of Philosophy to the Dept. of Indian Sub-Continental Studies, Faculty of Arts. Includes bibliographical references. Also available in print form.

Thesis (D. Min.)--Western Seminary, Portland, OR, 2006. / Abstract. Includes bibliographical references (leaves 187-193).

Thesis (Ph. D.)--University of Notre Dame, 2006. / Thesis directed by Michael Loux and Leopold Stubenberg for the Department of Philosophy. "April 2006." Includes bibliographical references (leaves 210-216).