عنوان مقاله [English]
Nature provides a variety of brilliant pigments which a number of them are of commercial value for use as color in foods, e.g. water-soluble natural colorants such as anthocyanins and betalains and oil soluble colorants such as carotenoids, curcumin, etc.
Betanins (CI Natural Red 33, E-number E162, betanidin 5-Ob- glucoside) are nitrogen-containing plant pigments whose colors range from red-violet betacyanins to yellow betaxanthins. They are used for coloring dairy products, meat and frozen desserts. Betalains have attracted additional interest because of their antioxidative, anti-inflammatory and anticarcinogenic properties. Betanine content in beetroot varies from 100 mg/100 g fresh product to 16– 38 mg/100 g dried vegetable product, i.e average amount of betalains in red beet has been estimated as 1000 mg/100 g of total solids, or 120 mg/100 g of fresh fruit. It has been reported that average amount of betanine in Cactus pears is 66-100 mg/100g of fresh fruit.
Betalain, extracted from red beet and Cactus pears is water soluble with high tinctorial strength. Betalain absorbs the visible radiation over the range of 476–600 nm with a maximum at 537 nm at pH 5.0. The color intensity is relatively unchanged from pH 3 to 7 but at pH values lower than 3 it turns more violet. At pH values higher than 7 the color becomes more yellowish-brown because of the loss of betanin. The present study was carried out to produce a dry powder of red color from bee root as a food colorants using microencapsulation technique. The red beetroots were purchased from the local market, washed in running water and manually peeled and cut in slices and homogenized in a centrifugal juice extractor. The homogenate was centrifuged, filtered, mixed with maltodextrin and ascorbic acid and finally spray dried. A factorial study also was carried out in order to assess the influence of operating parameters-temperature, solid/liquid ratio and pH, on the process’s performance. The analysis of beet juice colorant was performed using spectrophotometry and HPLC techniques. The results showed that using water as extracting medium with a ratio of 1:1 at 100 0C had the optimum efficiency in extracting betalain pigment followed by addition of 1% maltodextrin and ascorbic acid for encapsulation and finally spray drying.
Cactus pears (Opuntia) have been identified to be a promising betalainic crop, covering a wide colored spectrum from yellow to purple pigments, with potential application as natural colorant in food industry. In contrast to red beetroot, cactus fruits do not contain geosmin and pyrazines that are responsible for the unpleasant pettiness of the former, represents lower risk for microbiological contamination, are highly flavored, show adequate nutritional properties and contains interesting functional compound.