14B-12 |
Quality changes in chocolate during controlled atmosphere storage |
L. M. ANDRAE and N. J. Engeseth. Dept. of Food Science & Human Nutrition, Univ. of Illinois, Urbana-Champaign, 259 ERML, MC-051, 1201 W. Gregory Dr., Urbana, IL 61801 Bloom is the main cause of quality loss in the chocolate industry, compromising both visual and textural quality. Fat bloom forms when stored at elevated temperatures due to polymorphic transformation from unstable fat crystals to more stable forms. Sugar bloom forms at higher relative humidity due to deposition of water from the air onto the chocolate, dissolving the sugar on the surface before diffusing back into the air, allowing the sugar to recrystallize on the surface. Part of the appeal of chocolate is the smooth mouthfeel; as bloom forms a textural change is perceived. The objective was to analyze texture and color changes in dark chocolate and milk chocolate stored under various conditions. Chocolate was stored in incubators at 30°C and 32.2°C, desiccators at 25°C and 84.7% and 93.6% relative humidity, refrigerator (4°C), freezer (-20°C), and a temperature controlled storage room (22°C). Texture was measured using the TA-XT2 Texture Analyser with a two-bite compression test (25% compression with force of 20g). Color changes were measured on the Hunter Lab Colorimeter. Samples were analyzed, in triplicate, at 1, 3, and 5 weeks of storage. Large variation was observed initially, but during storage equilibration occurred and textural changes were detected. Milk chocolate samples stored at elevated temperatures exhibited a large decrease in springiness (40%) and cohesiveness (54%), indicating that these samples were easier to deform, possibly due to loss of fat in the chocolate matrix. Chocolates with sugar bloom were 12-15% lighter in color, while samples with fat bloom were 25-30% more yellow in color. Samples stored in the refrigerator and freezer had the least textural change, but were the most visually compromised. These results indicate that there may not be a storage condition that does not compromise either the textural and/or visual quality of chocolate.
Session 14B, Food Chemistry: Physicochemical properties
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