Water extraction of pigments in dragon fruit peel (Hylocereus sp.) and its stability

Dragon fruit known as pitaya or pithaya is one of the tropical fruits. Dragon fruit is popular for its attractive colour, juicy and sweet taste. Therefore, the skin of dragon fruit and seeds is often regarded as residual. Dragon fruit peel contains anthocyanin can act as natural food dye in order to replace the synthetic dye that has been commonly used in food industry. The objectives of this study are to investigate the extractive of dragon fruit peel using water extraction method and to study its stability since there are limited studies about the extraction of anthocyanin pigment using water extraction. The extraction was conducted using different water temperature to observe the yield of pigments produced and its storage ability in different condition. The results showed that total anthocyanin pigments extracted in 20°C was 0.224 mg L-1 showed the highest than other temperature. The stability of the extract in different condition presented that samples stored in pH 4; dark; 4°C and pH 4; light; 4°C showed the most stable. Colour stability was observed and resulted in decreasing of colour in redness. All samples stored in various factors resulted in changes of red colour to yellow colour except for samples stored in pH 4; dark; 4°C and pH 4; light; 4°C. The colour difference, AE between sample and standard was calculated to see how far storage affected on the colour samples. The statistical analysis shows that the temperature factor shows significant different p<0.05 meaning that different temperature is the one that influence on the colour stability.