Rheology of Prebiotic Chocolate
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Date
2011-06
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The Ohio State University
Abstract
Galactooligosaccharide (GOS) is a carbohydrate that has been identified as a prebiotic and is being investigated to have health benefits. Prebiotics are poorly digested ingredients that selectively increase the limited number of beneficial bacterial species in the colon. Unfortunately, in chocolate, textural changes occur due to addition of GOS and/or replacement of sugar. The goals of this study were to characterize the rheological behavior of various levels of GOS in chocolate (9.75%, 40%, and 80%) compared to the control formula (no GOS added) and to investigate whether replacing 80% of sugar with GOS would affect the texture of chocolate. Raw materials were purchased from vendors and local grocery stores. During the refining process, sucrose and GOS were added to the melted chocolate and cocoa butter and soy lecithin were added to the refined chocolate during conching. Once tempering was done, tempered chocolate was poured into a plastic mold. A rheometer with a concentric cylinder attachment was adapted to analyze the texture of the chocolate bar. Yield stress, apparent viscosity, and thixotropy of the four samples were measured using the steady state shear measurement in a shear-rate controlled rheometer. The averaged values were calculated for each attribute and analyzed for statistical differences (ANOVA, α = 0.05). There were statistical differences in yield stress and apparent viscosity. However, there were no statistical differences between each variable and the control for thixotropy (p>0.061). In addition, the sensory results showed that there were no statistical differences between the control and chocolate with GOS at low concentration. The rheological differences between the control and chocolate with low concentration of GOS should not have a large effect in relation to their parameters when fat and emulsifier contents are controlled. Therefore, the study suggested that under the same conditions, GOS could have great potential as a sucrose replacement in chocolate.
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Rheology of Prebiotic Chocolate