71A-18 |
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J. F. VÉLEZ-RUIZ, Chemical and Food Engineering, Universidad de las Américas - Puebla, Ex-Hda. Sta. Catarina Mártir, Cholula, Puebla, 72820, Mexico, M. E. Sosa-Morales, Food Engineering Dept., Universidad de las Américas, Puebla, Ex-Hda. Sta. Catarina Mártir, Cholula, Pue., 72820, Mexico, and P. Hernández-Carranza, Chemical and Food Engineering, Universidad de las Américas, Puebla, Ex-Hda. Sta. Catarina Mártir, Cholula, Pue., 72820, Mexico. Food fortification with fiber and calcium has recently received great attention because of its role in human nutrition; additionally, fat reduction in foods is a consumer concern. Fiber and calcium presence with fat reduction modifies the structure, and consequently some yogurt properties are modified. Therefore, the aim of this study was to manufacture yogurt at different levels of fiber and calcium fortification with fat decreasing, and to analyze the influence of these factors on their properties. Twenty four yogurt systems were elaborated, with two contents: 0.5 and 1.0 g of fiber from two sources; two levels of salt: 50 and 100 mg of salt; and three percentages of fat: 1, 2, and 3. The yogurt was prepared from standardized milk, and all samples were characterized at the beginning and during three weeks of storage. In comparison with a control, the first observable effect of the yogurt formulation was detected in a longer fermentation time to reach a pH of 4.5. The overall yogurt changes of the studied factors were: pHs augment, syneresis increasing, luminosity diminution and viscosity increasing, but with different trends as a function of the specific one. Furthermore, two of the most affected yogurt characteristics were the syneresis and the consistency; thus, due to the fat decreasing, some settled yogurts behaved as stirred ones. Syneresis degree augmented with the fat content. Higher apparent viscosities were correlated with higher fiber/calcium levels and major fat content. All formulations behaved as non-Newtonian fluids in which the Power Law model fitted very well (R2 > 0.90) the ascendant flow curve. Storage time influenced the rheological properties of the formulated yogurts—increasing in the flow behavior index and decreasing in the consistency coefficient were observed. The formulated yogurt systems were sensory evaluated by a nontrained panel showing good scores in their attributes.
Session 71A, Dairy Foods: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |