Year: 2017 | Month: December | Volume 7 | Issue 2
Anthocyanins: Chemistry, Extraction, Stability, Significance and Application as a Biocolour
Abstract:
Colour is a vital constituent of food and its preferences are influenced by the geographical, sociological and cultural aspects of the populations. The food industry have a vast array of synthetic colours made available in the late 1800s and are used very extensively in various food products. In the last twenty years however, consumers have become increasingly aware of the ingredients in their foods and as such they require foods to be as ‘natural’ as possible. Natural colours, extracted from fruits, vegetables, seed, roots and microorganisms are often called “biocolours” due to their biological origin. These colors are chlorophyll, carotene, lycopene, anthocyanins, flavonoids and anthoxanthins. To identify the active health-promoting ingredients, focus is being made on the properties of the flavonoids, a large class of phenolic compounds that is abundant in fruits and vegetables. Anthocyanins (Greek anthos, flower and Greek kyanose, blue) are the largest group of water-soluble pigments in the plant kingdom known as flavonoids and a larger group of compounds known as polyphenols. Anthocyanins are responsible for the red, purple and blue hues in fruits, vegetables, flowers and grains. Different types of anthocyanin found in naturally are cyanidin, delphinidin, peonidin, malvidine and palargonidin. These are responsible for the attractive colour of Black currant nectar and they have been hypothesized as important antioxidant. Anthocyanin rich mixtures and extracts (not purified compounds) have been used historically to treat? An anthocyanin pigment is composed of an aglycone (an anthocyanidin) esterified to one or more sugars, and have four different structures, which are in equilibrium with one another but the relative amount of these structures,are varied and dependent on the pH and anthocyanin structure, Waste from industrial processes, such as wine or juice production is an excellent source of anthocyanin pigment with potential as a food colourant. An alcohol i.e. methanol or ethanol at different concentrations in combination with an acid i.e. hydrochloric acid or acetic acid or citric acid can be used for the extraction of anthocyanin. But the natural colours have lesser stability than synthetic or artificial colours. Due to highly reactive nature of anthocyanins, they degrade or react with other constituents in the medium, to form colourless or brown coloured compounds. The intensity and stability of the anthocyanin pigments is dependent on different factors. Various methods have been used to evaluate the degradation of anthocyanin i.e. pH differential method and substractive methods. Applications of anthocyanin extracts include coloration of acid fruit preparations, jams and preserves. However, relatively little is known about absorption of anthocyanin compounds after consumption in our body and of the mechanisms by which they exert their beneficial health effects. Increased knowledge of their bioavailability and therapeutic will result in better adoption of anthocyanin-based products as functional foods.
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