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dc.contributor.advisorPatil, Bhimu
dc.contributor.advisorCobb, Greg
dc.creatorVanamala, Jairam Krishna Prasad
dc.date.accessioned2005-11-01T15:51:36Z
dc.date.available2005-11-01T15:51:36Z
dc.date.created2004-08
dc.date.issued2005-11-01
dc.identifier.urihttp://hdl.handle.net/1969.1/2774
dc.description.abstractThis dissertation examines the effects of postharvest treatment and processing on biologically active compounds of orange juice, and ??Rio Red?? grapefruit and their ability to prevent chemically induced colon cancer in rat model. The first study evaluated the differences in flavonoid content of commercial ??made from concentrate?? (MFC) orange juices and ??not from concentrate?? (NFC) orange and grapefruit juices. Total flavonoid content of MFC orange juices (53 mg/100 mL; n = 12) was significantly (P ≤ 0.05) higher than NFC orange juices (36.5 mg/100 mL; n = 14). The second study investigated the ionizing radiation and storage effects on bioactive compounds and quality of ??Rio Red?? grapefruit. Results showed that storage and irradiation significantly (P ≤ 0.05) affected the bioactive compounds in grapefruit, however, the effect of storage was prominent. The third study examined the influence of irradiation and freeze drying on bioactive compounds of grapefruit. Irradiation of grapefruit prior to freeze drying resulted in enhanced (P ≤ 0.05) flavonoid content (naringin and narirutin). Freeze drying markedly reduced (P ≤ 0.05) lycopene content. Freeze drying and irradiation reduced (P ≤ 0.05) volatile compounds (d-limonene and myrcene), with the exception of ethanol. In the fourth study suppression of colon cancer development in Sprague Dawley rats by natural and irradiated grapefruits and their functional compounds, naringin and limonin, were evaluated.The total number of aberrant crypts (AC; P = 0.02), number of high multiplicity AC foci (ACF; P = 0.01), and proliferative index (P = 0.02) were lower and apoptosis (P = 0.02) was higher in azoxymethane (AOM) injected rats on experimental diets. However, only natural grapefruit and limonin only suppressed AOM induced expansion (P = 0.008) of proliferative zone and also enhanced apoptosis more effectively than other experimental diets indicating that natural grapefruit and limonin may serve as better chemopreventive agents compared to IGFPP and naringin. The present study indicates that postharvest quarantine doses of irradiation slightly alter composition of bioactive compounds and in turn marginally reduce the chemopreventive ability of grapefruit against the promotion stage of colon cancer. These results warrant the necessity of testing the impact of post harvest treatments on fruits and vegetables chemopreventive ability.en
dc.format.extent710186 bytesen
dc.format.mediumelectronicen
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.publisherTexas A&M University
dc.subjectgrapefruiten
dc.subjectcolon canceren
dc.subjectirradiationen
dc.subjectflavonoidsen
dc.subjectlimonoiden
dc.subjectterpernoiden
dc.subjectACFen
dc.subjectproliferationen
dc.subjectapoptosisen
dc.subjectcitrus juicesen
dc.titlePostharvest irradiation treatment effect on grapefruit functional components and their role in prevention of colon canceren
dc.typeBooken
dc.typeThesisen
thesis.degree.departmentHorticultural Sciencesen
thesis.degree.disciplineHorticultureen
thesis.degree.grantorTexas A&M Universityen
thesis.degree.nameDoctor of Philosophyen
thesis.degree.levelDoctoralen
dc.contributor.committeeMemberLupton, Joanne
dc.contributor.committeeMemberPike, Leonard M.
dc.contributor.committeeMemberTurner, Nancy
dc.type.genreElectronic Dissertationen
dc.type.materialtexten
dc.format.digitalOriginborn digitalen


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