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UBC Theses and Dissertations

The application of cranberry in the production and quality of fresh dairy products Tomiuk, Stephen


The antioxidant activity of an ethanol extract prepared from cranberries was investigated using the oxygen radical absorbance capacity (ORAC) assay, as well as in a model food emulsion representative of dairy-based emulsions. The cranberry extract exhibited 348.31 ± 33.45 Trolox equivalents (TE)/g in the hydrophilic ORAC assay. In the model food emulsion consisting of 25% lipid stabilized by sodium caseinate, the extract was readily incorporated at the homogenization step until a pH of 5.6 was attained without causing emulsion destabilization. Under thermal conditions (50ºC), the lag phase prior to propagation of conjugated dienes (CD) in all cranberry emulsions at pH 5.6 was significantly extended relative to untreated controls (P < 0.05). The formation of secondary lipid oxidation products (hexanal and pentanal) in sunflower oil emulsions became significantly reduced (P < 0.05), but only after 64 hours of incubation. In contrast, the development of hexanal and pentanal in butterfat emulsions were significantly reduced (P < 0.05) over the entire incubation period. Increasing the level of cranberry extract in all emulsions beyond a final pH of 5.6 had an adverse effect on emulsion stability, and this was met with a drop in oxidative protection. The acidity of the cranberry extract made it well-suited for use in a fresh cream cheese product, which requires the production of acid during manufacture. The cranberry extract was homogenized into a cream cheese premix consisting of milk and cream until a pH of 5.6 was reached. Cheese produced from 1.18 g extract/100 g premix had a light pink color that remained stable over 50 days of storage at 4ºC. The cheese curd was found to retain over 98% of phenolics from the extract after separation of the whey. The level of CD and the peroxide value in the final product were significantly lower (P < 0.05) as compared to the untreated control cream cheese, after two weeks of storage at 4ºC. This research shows for the first time that a cranberry extract rich in bioactives can provide color and flavor to fresh dairy products while also acting as a useful preservation agent.

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