Thesis (M.S.)--Wisconsin. / Includes bibliographical references (leaves 69-72).

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 190-191).

A study of changes in bananas during ripening at 16 ± 1°C and 25 ± 1°C is described. Peel color was evaluated subjectively and by reflectance spectrophotometry; rheological properties by parallel plate compression and viscometry; selected chemical properties by appropriate tests and histochemical and histological properties by light microscopy. The rate of peel color change at the higher temperature was roughly twice that at the lower. Higher temperature-ripened fruits did not develop a full yellow color due to chlorophyll retention in the peel. Also pulp-to-peel ratio for such fruits tended to be lower than that of fruits ripened at the lower temperature. The pulp of high temperature-ripened fruits became progressively softer and was reflected by a linear increase of deformation under 1 kg force. For a given peel color index, maximum force and linear limit of the tissue as well as a power-law consistency coefficient of the puree were generally lower during ripening at the higher temperature. Reducing sugars increased linearly throughout ripening at the higher temperature while at the lower temperature the reducing sugar content was essentially constant beyond color index 6. On the basis of peel color index, total sugar and moisture content were higher while starch and AIS levels were lower in fruits ripened at the higher temperature. Ripening temperature therefore influences the relations of color index to mechanical and chemical properties. Ripening was characterized by a gradual loss of rigidity as well as an apparent thickening of the cell wall in over-ripe pulp tissue. Tannins decreased during ripening but did not disappear completely. Esterified pectins were not detected in hard green fruit; however, substantial amounts appeared at peel color index 3, then decreased steadily during ripening. Peel color was the best overall index of stage of ripeness for both ripening temperatures. Although rheological and chemical properties at a given color index differed for the two ripening temperatures, these intercorrelations remained higher (P ≤ 0.01). It is recommended, that ripening temperatures be taken into account when the color index chart is used to estimate the stage of ripeness of bananas. / Land and Food Systems, Faculty of / Graduate

Thesis (Ph. D.)--University of Adelaide, Dept. of Horticulture, Viticulture and Oenology, 2002. / "November 2002." Includes bibliographical references (leaves 150-172).

Thesis (Ph.D.) - University of Queensland, 2002. / Includes bibliography.

Activity of polyphenol oxidase, concentration of 3, 4- dihydroxyphenylethylamine (dopamine), and concentration of ascorbic acid in the pulp of bananas as they ripened were measured and relationships between these factors and both the extent of browning and the susceptibility to discoloration of the fruit during a 30-minute holding period were studied. Moisture and protein content were determined also. Bananas from three lots were analyzed as purchased and after either two or four days of additional ripening. Initial browning of the filtrates of bananas and the increase in browning upon standing were greater as the fruit ripened. Protein content also increased with ripening. Moisture content of bananas increased significantly in those bananas held for four additional days. The specific activity of polyphenol oxidase (units of activity/mg protein) in bananas decreased with ripening, but when the activity was calculated on a basis of dry weight of banana no significant change was observed. Both the dopamine and ascorbic acid contents decreased in individual bananas with ripening. Decrease in the concentration of dopamine was the variable with the highest correlation to the increase in browning in ripening bananas. Both the increase in browning and the decrease in dopamine in ripening bananas were associated with a decrease in ascorbic acid content. Thus, the concentration of dopamine as influenced in part by concentration of ascorbic acid appears to be the limiting factor in the browning of bananas. The specific activity of polyphenol oxidase did not appear to be a limiting factor in the browning of bananas. Dopamine was located histochemically in the vacuoles of the latex vessels and in a few isolated parenchyma cells of banana. Polyphenol oxidase appeared to occur throughout the pulp. / Graduation date: 1974

The purpose of this study was to determine the proanthocyanidin content of bananas at the green, the ripe, and the overripe stages. Three bananas from each of three hands at each stage of ripeness, making a total of 27 bananas, were freeze-dried. The ground tissue was dispersed in methanol and the proanthocyanidin in the slurry was converted to anthocyanidin by heating in 0.8 N HCl-n-butanol containing iron (FeSO₄ . 7H₂0). The major anthocyanidin was identified as delphinidin with a minor pigment as cyanidin. Two sub-samples of each banana were analyzed in triplicate and the absorbance of anthocyanidin was read at a wavelength of 545 mμ. The proanthocyanidin content, expressed as milligrams of delphinidin chloride per gram of dried banana, averaged 19.7 for the green, 16.0 for the ripe, and 13.7 for the overripe. Differences in the proanthocyanidin content of the bananas due to ripeness were statistically significant. Moisture content averaged 71.3% for the green, 73.0% for the ripe, and 74.9% for the overripe. Proanthocyanidin content on a fresh weight basis, expressed as milligrams of delphinidin chloride per gram of banana, averaged 5.63, 4.33, and 3.44 for the green, ripe and overripe, respectively. The proanthocyanidin content of the bananas in this study was considerably higher than values previously reported. Analysis of the pulp rather than the extractable proanthocyanidin and a more acidic developer and one which contained iron were major factors contributing to the higher values. While the proanthocyanidin content decreased significantly with ripeness of the bananas, two other groups of workers reported decreases that were proportionately greater. Their data was based on extractable proanthocyanidin and polymerization of these compounds as the fruit ripens could account for their lower values. Conversion of unextractable polymers in the pulp to soluble anthocyanidin could account for the higher values in the present study. A high proportion of the variance for treatment mean was due to hand and relatively little due to banana on the hand, suggesting that fewer bananas from more hands could have been analyzed. A better method than skin color for assessing ripeness is suggested. / Graduation date: 1969

Title page, summary and table of contents only. The complete thesis in print form is available from the University of Adelaide Library. / "This study examined how the efficacy of 1-MCP varies throughout the year; the effect of concentration, duration and timing of ethylene application; the effect of hand position on the bunch; the timing of 1-MCP application in relation to ripening and harvest time; and the effect of ripening storage temperatures and chilling storage .. The findings of this study allow 1-MCP to be used in a more commercially reliable manner" -- from Abstract. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1256621 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2006

Title page, summary and table of contents only. The complete thesis in print form is available from the University of Adelaide Library. / "This study examined how the efficacy of 1-MCP varies throughout the year; the effect of concentration, duration and timing of ethylene application; the effect of hand position on the bunch; the timing of 1-MCP application in relation to ripening and harvest time; and the effect of ripening storage temperatures and chilling storage .. The findings of this study allow 1-MCP to be used in a more commercially reliable manner" -- from Abstract. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1256621 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2006

Title page, summary and table of contents only. The complete thesis in print form is available from the University of Adelaide Library. / "This study examined how the efficacy of 1-MCP varies throughout the year; the effect of concentration, duration and timing of ethylene application; the effect of hand position on the bunch; the timing of 1-MCP application in relation to ripening and harvest time; and the effect of ripening storage temperatures and chilling storage .. The findings of this study allow 1-MCP to be used in a more commercially reliable manner" -- from Abstract. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1256621 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2006