Antioxidant enhancement of anthocyanin pigment in purple fragrant rice ST during wine fermentation
Nguyen Phuoc Minh
Anthocyanins are of particular interest to the food colorant industry due to their ability to impart vibrant colors. They are the largest group of water-soluble pigments in the plants, which are responsible for the red, purple and blue hues. Anthocyanins have been incorporated into the human diet for centuries and have been used as traditional herbal medicines due to their diverse physiological abilities to treat conditions such as hypertension, pyrexia, liver disorders, dysentery and diarrhea, urinary problems and the common cold. Recently anthocyanin-containingmaterials are being incorporated into food products and such products require further research to demonstrate their physiological effects. Purple fragrant rice ST is a specific agriculture product in Mekong river delta, Vietnam containing a lot of nutritious elements such as amino acids, minerals and antioxidants. This purple fragrant rice contains about 75% of starch, with a very high mineral content, rich in amino acids that specifically contain large amounts of anthocyanins with the antioxidant effect good for the health of users. Purple fragrant rice wine is a traditional fermented product of ethnic minority people in Mekong river delta, Vietnam. However owing to poor knowledge of processing, this product can’t maintain its specific anthocyanin pigment. So it’s necessary to study the extraction method to enhance natural color of purple fragant rice. Our results show that temperature, ethanol concentration and extraction time have positive effect to pigment extraction. Specifically, optimal parameters of extraction include temperature 70 oC; ethanol 60% v/v. pH is nearly stable during wine preservation. Optical density of mixed wine has changed during preservation, high in the beginning and low after 1-2 weeks. Purple fragant rice wine mixed with the extracted pigment has the significantly improved appearance.