Browsing by Author "Jaakkola, Jenni"

The aim of this master’s thesis was to study the effects of flaking conditions on the quality properties of oat flakes and to simulate the flaking process in laboratory conditions. The review of literature deals with oat processing focusing on oat flaking and oat flake quality properties. The flaking process includes groats steaming and tempering, which plasticizes the groats when moisture is absorbed. Then the groats are flattened by a flaking roller mill. Increasing tempering temperature and time results in higher water absorption. Increasing tempering time also increases the amount of fines. Flake breakage in the process reduces the flake yield resulting in more costs. There are no published studies that evaluate the impact of steaming on flake quality properties. The aim of the experimental part of this thesis was to study the effects of flaking moisture on flake strength and quality. Kilned and unkilned groats were flaked in a laboratory-scale flaking machine. Laboratory-scale flaking was carried out with a standardized flake thickness 0,7-0,8 mm. In addition, the properties of five commercial oat flakes were analyzed. There was significant variation between the different commercial oat flakes in their both water hydration capacities and amount of fines. The results implied that flaking conditions have an effect to these flake quality properties. Oat flakes were significantly thicker with higher flaking moisture. The roll gap was tightened to produce the same flake thickness. Both the bulk density and the amount of fines decreased with higher flaking moistures. There were no significant changes in the pasting properties of flakes made of kilned groats compared to kilned groats. Increasing flaking moisture reduces the amount of fines. In addition, water absorption increased with high flaking moistures. Even a three-percent increase in flaking moisture improved the quality of oat flakes. Increasing flaking moisture in between 12-20 % had a beneficial effect on quality properties of oat flakes.