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Weak acids are commonly used in the food industry as food preservatives however a complete understanding of their mode of action is not available. This study aimed to gain an understanding of the inhibitory mechanisms of two weak acids: sodium acetate and sodium benzoate. The ability of these weak acids to perturb the internal pH of cells was determined, a phenomenon previously shown as a mode of action of weak acids. However, changes in pHi alone were not sufficient in explaining the growth inhibition observed with sodium acetate, suggesting that the weak acid anion may also contribute to growth inhibition. The effect of the accumulation of was weak acid anions was found to be a reduction of cellular amino acid pools, mainly glutamate. When cells were transferred from medium containing weak acid to acid-free medium, recovery of internal pH was shown to be dependent on glutamate synthesis. The relieving effects of methionine on weak acid inhibition were also investigated. The aim of this section of the study was to identify the mechanism by which methionine resulted in relief of weak acid inhibition. It was found that addition of weak acid resulted in a 16-fold increase of the intracellular concentrations of homocysteine. This methionine precursor has been shown to act as a competitive inhibitor of methionine for methyl-tRNA-synthetase. Addition of methionine is therefore proposed to reduce weak acid inhibition by reducing homocysteine pools by feedback inhibition and by out-competing the intermediate.

Call number: LD2668 .T4 1950 C73 / Master of Science

M.A. University of the Witwatersrand, Faculty of Humanities (Heritage), 2012 / This study is based on the Parktown Westcliff Heritage Trust (PWHT). The study focuses on the preservation, conservation and advocacy activities of the Trust in heritage management. It analyses how the Trust has managed to survive for over 40years and how it has adapted to the changes in legislation over time. Of particular salience, the study focuses on 3 historical moments in which the PWHT intervened to save buildings and landscapes from destruction. These moments span from 1965 to the present and they include the destruction of the Parktown Ridge from 1965 onwards, inner city-Newtown 1980 and the Beyers Naude Square in 2004. The moments selected for analysis, explore how the PWHT has managed to survive through two distinct political systems namely, apartheid and democracy. The analysis presented in this report draws attention to the application and interpretation of legislation and policy at both local and national levels in heritage management.

Digitized by Kansas Correctional Industries

Typescript, etc. / Digitized by Kansas Correctional Industries

Blueberries are well known for their high anthocyanin content and the health benefits. Fresh blueberries have limited shelf life and thus are kept frozen or processed. Since freezing is expensive, low cost processing methods, particularly drying are being devised. Various drying treatments were compared with regard to drying time and quality of the dried product in terms of anthocyanin and polyphenolic contents as well as antioxidant activity. The drying treatments involved high temperature in a cabinet dryer and low temperature in a heat pump dryer. Freeze drying was used as a reference treatment. Highbush (Vaccinium corymbosum L., cultivars Crunchie, Star, and Sharpe) and rabbiteye (Vaccinium ashei, cultivars Climax, Powderblue, and Brightwell) blueberries were used in this study. Pre-treatments included osmotic dehydration or skin abrasion. The temperature and concentration of the osmotic solution were the main parameters contributing to the reduction of drying time. Mechanical skin abrasion was more effective than osmotic dehydration in reducing drying time and minimising the loss of anthocyanin and phenolic contents of the blueberries in air drying treatments. The thickness of cuticle and the structure of epicuticular waxes affected the drying rate of different cultivars of blueberries. Liquid chromatography and mass spectrometry (LC/MS) was used to identify different anthocyanins in the blueberry samples. Delphinidin, petunidin, and malvidin were the main contributors to the total anthocyanin content of the fresh and dried samples. Degradation products of anthocyanins were observed in samples where the anthocyanin contents declined as a result of drying treatments. The anthocyanin content and profile, phenolic content, and antioxidant activity of mulberries (Morus nigra), and Makiang (Cleistocalyx nervosum), a Thai native fruit, were also analysed. There was no significant difference between total anthocyanin content of blueberries and mulberries. In contrast, the total phenolic content and antioxidant effect of mulberry were significantly higher than those of blueberries and Makiang. Skin abrasion and high temperature drying resulted in the fastest drying rate and highest anthocyanin retention. Anthocyanin profiles differed in various cultivars of blueberries. Within the same cultivar, amounts of each anthocyanin varied with pre-treatments and drying methods but the distribution of monomeric anthocyanins was similar.

This investigation was conducted to study the effects of blanching and storage temperatures on the color of strawberry juice and concentrate. Strawberry juice and concentrate (42°βrix) were prepared from blanched crushed Tioga strawberries. Crushed strawberries were blanched, in a steam-jacketed kettle, at 70°, 80°, and 90°C for 1 min. Ascorbic Acid (AA), at a level of 0.01%, was added to one batch and hoped to counteract polyphenol oxidase (PPO) activity in the early stages of processing. Samples were then stored at 1°, 21° and 38°C and the chemical composition as well as the color parameters were monitored throughout the study. Blanching at 70°C was found to heat-inactivate PPO in strawberries. Generally, blanching protected the compositional constituents, such as, anthocyanins (ACN), AA, leucoanthocyanins, flavanols and total phenolics. Initially, blanched samples contained higher concentrations of these chemicals than the unblanched (control) samples. Samples blanched at 80°C contained highest concentrations followed by those blanched at 90° and 70°C. This protective effect was markedly reduced in samples blanched with added AA. AA decomposition products seem to initiate other degradation reactions. There was a considerable decrease in the juice chemical constituents upon concentration. A particular striking decrease was observed with AA where samples lost more than 75% of their initial content. All samples experienced gradual losses of their chemical constituents accompanied by loss of the bright red color associated with freshly prepared juice and concentrate. The losses increased with increased storage temperatures. Storage at 38°C, as a result, was found to be a major factor in the loss of the chemical constituents and the rapid deterioration of the color. Concentrate samples developed burnt flavor by the third week and lost all ACN and AA contents by the end of the storage period. The loss was much less on storage at 21°C and least at 1°C. At any storage temperature, samples blanched at 80° and 90°C retained more of their constituents as well as better color quality parameters when compared to the control or those blanched at 70°C. Samples blanched with added AA experienced greater losses of their color values and chemical constituents, particularly ACN and AA, when compared to samples blanched without AA. ACN and AA degradation in samples stored at 1°C followed first order reaction kinetics, while browning formation in these samples and in juice samples stored at 21°C followed zero order reaction kinetics. Rate constants suggest a major role for AA in the deterioration of color. Moreover, they also suggest a protective effect on blanching on the overall quality of the juice and concentrate. Blanching at 80°C for 1 min was the optimum processing temperature investigated, while low storage temperatures are, naturally valuable in retaining better color quality strawberry juice and concentrate. / Graduation date: 1982

Thesis (M.S.H.P.)--Ball State University, 2009. / Title from PDF t.p. (viewed on Dec. 14, 2009). Includes bibliographical references (p. [83]-89).

6 pp. / The Dietary Guidelines for Americans recommend 2 to 3 cups of vegetables daily for adults. The USDA reports that more than half of our vegetable intake comes from potatoes and tomatoes, whereas only 10% comes from bright, colorful vegetables, including carrots. This article focuses on many ways to enjoy carrots, introducing different types of dishes that utilize carrots and methods of preserving them for later consumption. The nutritional value and health benefits of carrots are also explained.