DYNAMIC CHANGES IN POLYPHENOLS, FREE CARBOHYDRATES, AND ANTIOXIDANT ACTIVITY DURING GERMINATION OF WHEAT AND BARLEY FOR PREPARATION OF MALT FLOUR
YORDAN GEORGIEV 1, 2, MANOL OGNYANOV 1, MISHELA TEMKOV 3, GJORE NAKOV 4, 5* 1. Bulgarian Academy of Sciences, Institute of Organic Chemistry with Centre of Phytochemistry, Laboratory of Biologically Active Substances, 139 Ruski Blvd., 4000 Plovdiv, Bulgaria
2. Prof. Dr. Assen Zlatarov University, Faculty of Medicine, Department of Physiology, Pathophysiology, Chemistry and Biochemistry, 1 Prof. Yakim Yakimov Blvd., 8010 Burgas, Bulgaria
3. âSt. Cyril and Methodiusâ University in Skopje, Faculty of Technology and Metallurgy, Department of Food Technology and Biotechnology, 16 Ruger Boskovic Str., 1000 Skopje,
N. Macedonia
4. Technical University of Sofia, College of Sliven, 59A Burgasko Shose Blvd, 8800 Mladost, Sliven, Bulgaria
5. Agricultural Academy-Sofia, Institute of Cryobiology and Food Technologies, 53 Cherni Vrah Blvd., 1407 Sofia, Bulgaria
*Corresponding author: gnakov@tu-sofia.bg
The study aimed to determine the free sugar and total phenolic contents (TPC), and in vitro antioxidant activity in different wheat and barley malt flour. Thirty malt flour samples were prepared from wheat cultivars Lorena and SnaĆĄa, and malting barley Tristan, feed barley Zlatko, hull-less barley Osvit, and Mandatar, during different periods of germination from 1 to 4 days. The identified sugars in the samples were maltose, glucose (Glc), and sucrose, but fructose (Fru) and isomaltose were found in trace amounts. The maltose content was the highest, reaching up to 8.6 % among the detected sugars. The Glc content ranged between 1.0 % and 4.4 %, and sucrose was from 0.6 to 4.3 %. The samples Tristan (14.9 %) and Osvit (13.5 %) were characterized by the highest total free sugar content. SnaĆĄa flour contained high comparable amounts of soluble sugars (11.6 - 8.1 %) at 0 - 96 h of germination. The TPC and in vitro DPPH radical scavenging activity increased during germination, as they were higher in barley varieties than in wheat ones. Wheat and barley malt flour can be combined to increase the amounts of fermentable sugars and antioxidants to create bakery products, sourdoughs, craft beers, functional and dietary foods, and fermented drinks.
