M.A. Thesis:

Physicochemical and Sensory Properties of Black Prune Skin Marmalade

In this research, the effect of different levels of black prune skin (40 to 60 percent) and pectin (0.3 to 0.6 percent) on the chemical properties (brix, pH, acidity, total solids, insoluble solids and total ash), sensory characteristics (color, consistency, taste, firmness, adhesiveness, spreadability, overal acceptability) , independent rheological behavior (flow behavior index, consistency coefficient and apparent viscosity), texture properties (firmness, cohesiveness, consistency and index of viscosity) of black prune skin marmalade was investigated. The results of chemical and sensorial properties showed that adding the black prune skin caused add in acidity, while decreased color, flavor, adhesiveness, spreadability and overal acceptability (P<0.05). The increase of pectin led to decrease of acidity, flavor and spreadability scores (P<0.05). Increasing the percent of black prune skin and pectin in other characteristics were not significant (P>0.05). the black prune skin marmalade showed a pseudoplastic behavior well described by the power – law model. Increasing the pectin and prune skin caused the marmalade more harden and thicken and higher viscosity. In the study of textural properties, adding the percentage of black prune skin increased the firmness, cohesiveness, consistency and index of viscosity. Increasing the pectin percentage caused to increase the firmness and consistency.

Keywords: Black prune, Sensory poperties, Rheology, Texture, Marmalade.