AMILASE PADA UBI JALAR UNGU (Ipomoea batatas) VARIETAS KOLAKAN: PENGARUH PH DAN SUHU TERHADAP AKTIVITAS DAN STABILITAS

Sweet potatoes is one of staple food among the other main food that has a great potential and has been developed in Indonesia. Sweet potatoes is the main source of carbohydrates and has a sweet taste. Purple-fleshed sweet potatoes is one of the popular variety among the other variety of sweet potatoes because it is known has a high amount of antioxidant. Purple-fleshed sweet potatoes that used in this research was Kolakan Variety. It will be developed to substitute the use of Sweet Potatoes Madu variety, that already popular as the roasted sweet potatoes. Endogenous amylase enzyme inside the sweet potatoes can breakdown the starch into reducing sugar especially maltose. Nature�s condition will influence the amylase enzyme activity and stability such as pH and temperature. The result of the research will be used to give the optimum pH and temperature for the sweet potatoes food processing in manufacture, café, or restaurant. The experiment of pH variation in amylase activity are using citrate buffer pH 3, acetate buffer pH 4, acetate buffer pH 5, citrate buffer pH 6, phosphate buffer pH 7, and phosphate buffer pH 8. The experiment of temperature variation in amylase activity are using 30, 40, 50, 60,70, 80, and 900C. The experiment of temperature variation in amylase stability are using the temperature around the optimum temperature. The assays using total amylase assay of DNS reducing sugar. The result of the experiment shows that the optimum pH is 6, the optimum temperature is 500C, and the temperature stability are 30, 40,dan 450C for 8 hours. Key words : Amylase enzyme, purple-fleshed sweet potatoes, optimum pH