Dry powder of red color from roselle calyces, which can be used as natural colorant and functional food ingredient, was produced using microencapsulation technique. Four different matrices, i.e., maltodextrin, gum Arabic, combination of maltodextrin and gum Arabic, and soluble starch were used for encapsulation study. Identification and measurement of anthocyanins in encapsulated roselle was made by high‐performance liquid chromatography. Encapsulation efficiencies were determined and compared with storage analysis data. The stability of encapsulated pigments was investigated during storage under three different storage temperatures (4, 25 and 37C) until 105 days. The four type of matrices largely increased the half‐life of the pigments during storage especially at 37C (P < 0.05) compared with the non‐encapsulated roselle extract. Storage temperature did not significantly (P > 0.05) effect the L*, a* and b* values. However, type of encapsulation agent and storage time significantly (P < 0.05) affected the color changes. The L* and a* values were decreased during storage whereas the b* value was increased. Combination of maltodextrin and gum Arabic showed the highest encapsulation efficiencies (99.87 ± 0.04%), lower degradation rate in 4C (3.7 ± 0.3) and had smaller changes in a* and b* values among the four matrices.
PRACTICAL APPLICATIONS
A spectrum of natural, red‐hue primer colorants derived from roselle plant extracts, substantially free of alkaloids, enzymes, aroma or solvent residuals, and microencapsulated to ensure good stability and shelf life. This study measures the storage stability and suitability of the microencapsulated natural colorants. The colorants are for functional use in the food, pharmaceuticals, cosmetics and other industries.
The stability of roselle anthocyanins was investigated under three different heat treatments (60, 80 and 98C). The dry red powder from roselle calyces was produced using spray-drying technique using four different encapsulating agents, i.e., maltodextrin, gum arabic, a combination of maltodextrin and gum arabic, and soluble starch. The four types of matrices increased the half-life of the pigments during heat treatment, especially at 98C (P < 0.05), compared with the roselle extract as the control. Heat treatment results showed that the combination of maltodextrin and gum arabic had the lowest degradation kinetic rates at 60 and 80C. Arrhenius parameters' results further confirmed that the degradation of anthocyanins was strongly dependent on the operating temperatures during heat treatment. In this study, all encapsulating agents, except the soluble starch, largely elongated the halflife of roselle anthocyanins compared with the nonencapsulated anthocyanins.
PRACTICAL APPLICATIONSA spectrum of natural, red-hue primer colorants is derived from roselle plant extracts, which is substantially free of alkaloids, enzymes, aroma or solvent residuals, and is microencapsulated to ensure good stability and shelf life. This study measured the thermal stability and suitability of the microencapsulated natural colorants. The colorants are for functional use in the food, pharmaceuticals, cosmetics and other industries.
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