Thesis (M.S.)--University of Michigan, 1984.

Thesis (M.S.)--University of Michigan, 1984.

Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Sept. 2, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Materials Engineering, Department of Chemical and Materials Engineering, University of Alberta." Includes bibliographical references.

The properties of factors present in boiled yeast juice which stimulate the oxidative breakdown of citrate in baker's yeast have been investigated. The activity has been shown to reside predominantly in the nucleotide fractions (i.e., pyridine codehydrogenases) and to a lesser extent in the ammonium salts present in whole yeast cells. The activity of the Citrate Oxidation Factor (COF) concentrated from yeast extracts and described by Foulkes (Biochem. J. 54 323 (1953)) was attributable entirely to the ammonium content of COF preparations. This activating effect of ammonium ions is accompanied by their removal from the assay system and the simultaneous production of glutamic acid. Correlation of the uptake of ammonium ion with the increased citrate metabolism indicates that the activity of the ammonium salts lies in their ability to promote the reductive amination of α-oxoglutarate. The mechanism(s) whereby this serves to stimulate the further breakdown of citrate to oxoglutarate involves the mediation of the pyridine codehydrogenases (DPN, TPN). These findings are discussed in relation to the known functioning of individual stains of the tricarboxylic acid cycle and to possible alternative pathways for the oxidation of citrate in yeast.

No description available.

No description available.

Les solutions électro-activées (SEA) obtenues par excitation électrique de solutions aqueuses sont actuellement étudiées par leur haut potentiel de préservation des aliments en raison de leurs propriétés antimicrobiennes et sporicides. Ainsi, ce projet visait à électro-activer des solutions aqueuses de citrate (CS), de propionate (PS) et d’acétate de sodium (AS) pour les utiliser comme saumures dans un procédé de conservation de betterave rouge (BR). Dans ce projet, le taux d’acidité titrable (% AT), le pH et le potentiel oxydo-réduction (POR) des SEA générées ont été étudiées en fonction de la concentration du sel, de l’intensité de courant électrique (IC) appliquée et du temps de traitement qui s’est étalé sur une période de 75 minutes. Ensuite, trois SEA de chaque type de sel ont été sélectionnées selon le % d’AT : minimal (≈0,8), moyen (≈1,3) et maximale (≈1,5) et utilisées tant pour blanchir des morceaux de BR à 90 °C pendant 3 min comme que pour la mise en conserve du produit. La qualité microbiologique, chromatique et texturale a été évaluée en fonction du type de SEA utilisé pour la conservation du produit pendant un mois. Les résultats obtenus montrent que l’IC est le facteur qui influence significativement les propriétés des SEA. Des valeurs de pH de 1,5 à 4, de POR d’environ +500 mV pour le citrate et +1200 mV pour le propionate et l'acétate, et un % d’AT de 0,8 à 2 mmole/L (1.5 pour l’acétate de sodium) ont été obtenues. Les SEA de citrate de sodium et de propionate de sodium ont montré une très bonne activité antimicrobienne même à 0,8 % d’AT, tandis que pour l’acétate de sodium, cette activité était observée à 1,5% d’AT. La couleur est devenue plus pâle avec le temps de conservation et la force de mastication a été en général peu affectée. / Electro-activated solutions (EAS) obtained by electrical excitation of aqueous solutions are currently being studied for their high food preservation potential due to their antimicrobial and sporicidal properties. Thus, this project was aimed to electroactivate aqueous solutions of sodium citrate (CS), sodium propionate (PS) and sodium acetate (AS) to use them as brines in a conservation process of beetroot (BR). In this project, the electro-activated solutions titratable acidity (% TA), the pH and the oxidation-reduction potential (ORP) of the generated EAS were studied as a function of the salt concentration which was set for a total period of 75 minutes. Then, three EAS of each type of the used salts of organic acids were selected according to their % of TA: minimum (≈0.8), medium (≈1.3) and maximum (≈1.5), and were used in combination with a blanching process at temperature of 90 ° C for 3 min as a process for beetroot canning. The microbiological, chromatic and textural quality of the canned product was evaluated according to the type of ESA used for the preservation of the product during one month at ambient temperature (23 ± 1 °C). The results obtained showed that the CI is the factor which significantly (p < 0.001) influenced the properties of the ESA. The pH values of 1.5 to 4, ORP of around +500 mV for the electro-activated (EA) sodium citrate solution and +1200 mV for the EA sodium propionate and sodium acetate solutions, and %AT of 0.8 to 2 mmole/L (1.5 for EA sodium acetate solution) were obtained. The EAS of sodium citrate and sodium propionate showed very good antimicrobial activity even at 0.8% of TA, while for the EA sodium acetate solution, this activity was observed at 1.5% TA. The color of the canned beetroot became lighter over time and the corresponding chewing force calculated by textural profile analysis (TPA) analysis was generally slightly affected by the used preservation procedure.

Thesis (M.S.)--University of Michigan, 1983.

Thesis (M.S.)--University of Michigan, 1989.

Thesis (M.S.)--University of Michigan, 1984.