Stability of black carrot anthocyanins in the turkish delight (LOKUM) during storage
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In this research, traditional Turkish delight (lokum) was colored with black carrot juice concentrate, and the variations in anthocyanin content, during storage at different temperatures (12, 20 and 30C) for 5-month periods, were observed by spectrophotometer and high-performance liquid chromatography. Analysis of kinetic data suggested a first-order reaction for the degradation of black carrot anthocyanins in Turkish delight. Degradation rates of anthocyanins of black carrot increased with increasing temperature. It was determined that the degradation rate of black carrot anthocyanins during the storage period at 12C increased faster than that of the other temperatures (20 and 30C). The k values for 12, 20 and 30C were found to be 6.91 × 10 -3, 4.21 × 10 -3and 9.21 × 10 -3/day, respectively. Effects of pH on the thermal stability of black carrot anthocyanins were also determined. Results showed that the stability of anthocyanins decreased as the pH value increased. Increase in pH values correlated well with the decrease in anthocyanin content of the samples during storage. In all of the samples, redness (a*) decreased during the storage at all temperatures; however, lightness (L*) increased. PRACTICAL APPLICATIONS Most of commercial anthocyanins used as a colorant in foods are obtained from fruits or vegetables such as: red grape, elderberry, blackcurrant, blackberry, raspberry, black chokeberry, red cabbage, black carrot, purple corn, red radish and purple sweet potato. Turkish delight (lokum), one of the most popular traditional food products in Turkey, is a famous Turkish desert known all over the world. Lokum is produced by using sugar, water, starch, citric acid, aromatic compounds, dried fruits and natural colorant. The color of foods, which is one of the initial properties noticed in foods, is one of the most important quality parameters affecting consumers. Because of consumer anxiety over the safety of synthetic food colorants, the demand for natural food colorants has increased. Particularly, there is an increasing request for natural red food colorants as alternatives to the most commonly used synthetic red colorant. Therefore, the availability and the suitability of black carrot juice concentrate as a natural colorant instead of synthetic colorants which are considered to have some negative properties for human health was investigated by this work. © 2009 Wiley Periodicals, Inc.