71A-20 |
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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 J. A. Rivas-Badillo, Chemical and Food Engineering, Universidad de las Américas, Puebla, Ex-Hda. Sta. Catarina Mártir, Cholula, Pue., 72820, Mexico. Custards, or “natillas,” a semisolid dairy dessert of wide consumption in some countries, is increasing its importance in Mexico. They are dairy products composed of milk, starch, hydrocolloids, sugar, colorants, and aromas. Even though there is commercial significance of custard products containing starch, there is limited fundamental information available on the flow and physicochemical characteristics of these complex dairy systems. Thus, the objective of this research was to study the properties of some custard model systems formulated with skim and whole milk, including two levels of starch and two levels of carrageenan gum. The formulated eight custard models were analyzed through three weeks of storage at 4 °C, in which the flow and physicochemical properties were measured. The obtained results indicated that moisture and density, as expected, were constant through the storage time, as was the pH and acidity. These (pH and acidity) showed some changes during storage, but there was not significant difference (Α=0.05) between means. Percentage of syneresis augmented significantly, from 20% or less at the zero day up to 30 to 60% at the fourth week of storage. Net color differences did not show a defined trend, they were low in magnitude (2 to 7). Both flow and texture properties changed importantly as a function of the composition; some systems exhibited yield stress and were fitted by the Herschel-Bulkley, and the rest of the systems were of Power Law type. All the systems behaved as non-Newtonian fluids. in which the starch influenced the rheological response. The flow behavior index did not change significantly with the storage, contrary to the consistency coefficient and yield stress in which a decreasing trend was observed during the storage time. The texture, expressed as adhesion force, also exhibited a decreasing pattern, reflecting some structural changes of the custard system.
Session 71A, Dairy Foods: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |