Technical Session 05: Malts and Grain Session
Mekonnen M Gebremariam, Institute for Brewing and Beverage Technology, Technische Universität München, Freising, Germany
Co-author(s): Martin Zarnkow and Thomas Becker, Institute for Brewing and Beverage Technology, Technische Universität München, Freising, Germany
ABSTRACT: Teff is a gluten free cereal with an attractive nutritional profile, making it a suitable substitute for barley, wheat, and other cereals in their food applications and foods for people with celiac disease. The demand for gluten free foods is certainly increasing. The aim of this research was to study the influence of kilning on enzyme activities and DMS level of teff variety DZ-Cr-387 and suggest a kilning condition that yields teff malt with low level of DMS with no or little damage on its enzyme activities. The teff samples were steeped for 5 hr on the first day, and 4 hr on the second day at 24°C and germinated for 4 days at 24°C in a temperature controlled chamber with 95% relative humidity. The green malts were dried using isothermal conditions at 30, 40, 50, 60, and 70°C for 40 hr with sampling at certain time intervals. To set up optimum kilning conditions, two temperature regimens were selected based on the results of the isothermal kilning and some other trial experiments: 18 hr at 30°C + 1 hr at 60°C + (3 and 5) hr at 65°C (R1), and 18 hr at 30°C + 1 hr at 60°C + (3 and 5) hr at 80°C (R2). The results from the isothermal kilning indicate that enzyme activities of teff malt decreased as the kilning time and temperature increased. At lower temperatures, there was an increase in the enzyme activities as the kilning time increased. The DMS contents decreased with an increase in temperature and time. The first kilning regimen (R1) with 3 hr curing at 65°C resulted in teff malt with alpha-amylase, beta-amylase, and limit dextrinase activities and DMS content of 68 U/g, 440 U/g, 1,072 U/kg, and 3.3 mg/kg, respectively. The same kilning regimen (R1) with 5 hr curing at 65°C yields teff malt with alpha-amylase, beta-amylase, and limit dextrinase activities and DMS content of 60 U/g, 421 U/g, 780 U/kg, and 2.5 mg/kg, respectively. Whereas the second kilning regimen (R2) with 3 hr curing at 80°C resulted in teff malt with alpha-amylase, beta-amylase, and limit dextrinase activities of 42 U/g, 406 U/g, and 736 U/kg, respectively, and DMS content of 2.15 mg/kg. The same kilning regimen (R2) with 5 hr curing at 80°C yields teff malt with alpha-amylase, beta-amylase, and limit dextrinase activities of 37 U/g, 395 U/g, and 594 U/kg, respectively, and DMS level of 1.7 mg/kg. The results in general show that the teff malt, which was kilned using the first kilning regimen with shorter curing time at 65°C, contained the highest level of amylolytic enzymes. The DMS values in all teff malts were below the threshold level (5 mg/kg) that good quality malt should contain. It can be concluded that the first kilning regimen (R1) with shorter curing time is the best kilning condition that yields a good quality teff malt. The levels of enzyme activities and DMS show that teff can be a suitable alternative raw material for production of good quality gluten free beer.
Mekonnen Melaku Gebremariam received his B.S. degree in chemistry from Debub University, Ethiopia. He began employment with the Ethiopian Ministry of Education in July 2000 as a chemistry teacher in the South Nations and Nationality People Region. He terminated his contract agreement with the Ministry of Education after four years. He next was employed as a chemist in the Federal Micro and Small Enterprises Development Authority. After 18 months with this company, he terminated the contract agreement and joined Addis Ababa University for further studies. He graduated from Addis Ababa University, Ethiopia, in 2007 with an M.S. degree (with great distinction) in food engineering. Immediately after graduation he was employed as a lecturer and researcher by Hawassa University, Ethiopia. After about two-and-a-half years of work at Hawassa University, he went to Germany for his Ph.D. studies with the support of his employer, Hawassa University. Currently he is pursuing his doctoral studies at the Technical University of Munich, Germany.