Sensory and Chemical Stability of Vacuum Packaged Wagashie

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Wagashie samples from unpasteurized full-fat milk (UFFM), pasteurized partially skimmed milk (PPSM) and pasteurized full-fat milk (PFFM) were prepared and a fourth (control termed as ‘D’) was purchased from the market. The study was to provide descriptive vocabulary for Wagashie, determine sensory and chemical changes during storage, and to establish relationships between sensory attributes and chemical parameters. Vocabulary was generated by twenty panelists using quantitative descriptive analysis. All the four Wagashie samples were vacuum-packaged and stored for four weeks at 12 oC. Sensory evaluation was carried out on zero and four week old samples using a line scale of 0 (strong) to 10 (weak). Chemical tests (moisture, crude protein, fat, free fatty acid and pH) were conducted on week zero, one, two and four. In all twenty attributes (eleven for the cooked and nine for fried Wagashie forms) were generated. However, fried Wagashie samples were considered for the rest of the research because preliminary survey showed that Wagashie is mostly consumed in the fried form. The fried Wagashie attributes were golden brown, rough and compact, firm, soggy, chewable and friable, typical of Wagashie aroma and flat taste. Four week old samples compared with zero week old ones showed significant differences (P< 0.05) for some attributes and insignificant differences (P> 0.05) for other attributes. However, they were all within the same region of the scale (either 1 to 5, or 6 to 10). For attribute flat, week zero old samples compared with their respective four week old samples showed significant differences (P< 0.05) and fell within different regions of the line scale except sample PFFM. In terms of chemical tests after the storage period, percentage moisture and FFA reduced and increased (P< 0.05) respectively. Protein remained unchanged (P> 0.05) in sample PPSM and PFFM but increased (P< 0.05) in the other two. Fat increased in PPSM and D but reduced in the other two samples (P< 0.05). pH of all the Wagashie samples reduced at the end of storage. Correlation analysis showed that a reduction in the percentage fat increased the friability of UFFM sample. Also, increase in FFA altered the taste of all the samples except PFFM. The study showed that the least and greatest change occurred in PFFM and D respectively after storage.
A thesis submitted to the Department of Biochemistry, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the award of the degree of Master of Science (MSc) in Food Science and Technology.