THE EFFECT OF PREPARATION BEFORE DRYING ON CHEMICAL AND FUNCTIONAL PROPERTIES OF PURPLE YAM FLOUR (Dioscorea alata L.)
Siti Tamaroh (a), Tyastuti Purwani (b)

1.Faculty Agroindustry,
Universitas Mercu Buana Yogyakarta

2. Jln. Wates Km 10, Yogyakarta, 55753

Abstract

Purple yam (Dioscorea alata L) is a carbohydrate source tuber that contains natural anthocyanin dyes. Anthocyanins found in purple yam are useful as natural antioxidants, anticancer, antihypertensive. Purple yam is easily damaged, it needs processing efforts to become a material that is resistant to storage and easy to use as food, that is flour. In the manufacture of flour, there is a drying process. The drying process takes a long time, which allows damage to the nutritional components of the material. Pretreatment with maltodextrin can protect nutritional components, color, flavor, and storage during drying. The degree of oxidation was carried out to determine the browning index. The low browning index of purple yam tubers can be done by soaking in citric acid. This study aims to produce purple yam flour with high antioxidant activity and not brown. In this study, purple yam flour was made by immersing 0.5 and 1% (v/v) citric acid for 10 minutes and soaking in 10, 20, 30% (w/v) maltodextrin solution for 5 minutes and dried at 55 oC, after drying sieved through an 80 mesh. The resulting purple yam flour was tested for antioxidant activity, phenolic total content, and anthocyanin levels and water content. The purple yam flour with the highest antioxidant activity was tested for protein content, ash content, fat content and carbohydrate content by difference. The data obtained were carried out in duplicate. The data obtained were tested statistically by the SPSS method and if significantly different, then continued with the ^Duncan New Multiple Range Test^ (DMRT) at the 5% degree of confidence. The research results show that immersion treatment in 1% v/v citric acid and 30% w/v maltodextrin can produce purple yam flour with highest antioxidant activity 88.30%, with anthocyanin content 16.64 mg/100 g db and phenolic total content of 473.63 mg GAE/100 g db. The physical properties of the flour are as follows: browning index (BI) = 0.28, swelling power (SP) = 15.3

Keywords: purple yam flour, citric acid, maltodextrin

Topic: Food Processing and Packaging