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KMID : 1011620190350020159
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Korean Journal of Food and Cookey Science
2019 Volume.35 No. 2 p.159 ~ p.168
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Influences of the Alginate-Calcium Ratio and Reaction Time on the Quality of Coffee Beads Prepared by Basic Spherification
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Surh Jeong-Hee
Yang Hee-Wan
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Abstract
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Purpose: This study examined the factors influencing the preparation of coffee beads by spherification for a novel application of coffee. The factors were as follows; alginate-calcium ratio (R) and reaction time between the two reactants.
Methods: Based on the fact that negatively-charged alginate molecules are bridged by calcium divalent cations (Ca2+) through electrostatic attractions and a calcium-alginate gel is formed, coffee beads were prepared at different R (0.38 to 1.13) and reaction times (30 to 210 sec). The texture and sensory attributes of the beads were then characterized.
Results: At a relatively lower R, the sphericity and hardness of the beads increased with increasing R, showing that the alginate concentration was a critical factor for bead formation. Coffee beads formed at relatively higher R had lower cohesiveness and springiness. This was attributed to the densely cross-linking gel structure surrounding the bead surface that could block the inward diffusion of Ca2+. The phenomenon appeared to improve the sensory preference, presumably due to the loss of less coffee flavor components through the compact bead surface. The coffee beads prepared at R=0.63 showed an increase in sphericity and hardness with increasing reaction time, without any change in cohesiveness. This indicates that Ca2+ ions were used to form a Ca-alginate membrane around the bead surface to increase the gel strength, instead of further diffusing inward. The sensory evaluation showed that the textural properties related to gelation and to the density of the Ca-alginate membrane were the determining factors for preference.
Conclusion: These results suggest that the R and reaction time in preparing coffee beads by spherification affect the textural and sensory properties of the coffee beads, which could be due to the possible changes in the structure of the Ca-alginate membrane. This study provides valuable basic information for the production of coffee beads.
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KEYWORD
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coffee bead, spherification, alginate, calcium, gel
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