Affect of Flaxseed Particle Size on Bread Quality

Clifford A. Hall III*, Mary Niehaus, Scott Meyers

North Dakota State University

Mehmet Tulbek, Bonnie Jacobson

Northern Crops Institute

*Corresponding author: 210 Harris Hall, Dept. Cereal Food Sciences, NDSU, Fargo, ND 58105. clifford.hall@ndsu.edu, 701-231-6359.

ABSTRACT

Flaxseed has been widely accepted as an ingredient in breads. The level of flaxseed addition to breads and bakery products has been investigated extensively; however, limited research on the impact of particle size on bread quality has been reported. Thus, the objective of this research was to determine the effect of milled flaxseed particle size on bread quality. Yellow Omega flaxseed was ground using an Urschel type mill and then separated on a Roto-Tap device according to mesh size. The particle sizes separated were grouped into the following based on retention on the appropriate sieve:  20 (850 µm), 30 (600 µm), and 30-60 (<600 µm) mesh. A milled sample containing all particles was used in the production of control breads. The milled flaxseed or separated particles then were added to flour at a 15% level. Bread volume, firmness, cell structures, fatty acid profile, and sensory characteristics were evaluated at days 1, 4 and 7 after baking. The loaf volume of bread made with the 850 µm and 600 µm flaxseed particles were greater than control bread and bread made with flaxseed particles <600 µm. The smaller particles also created more dense bread as observed by the imaging of the crumb. A general trend upwards in firmness was observed in breads made with decreasing flaxseed particles. However, sensory panelists were not able to detect differences in firmness. Similar trends were observed for staleness. Breads made with the flaxseed 850 µm and 600 µm flaxseed particles had lower lipid and α-linolenic acid contents than the breads made with the <600 µm particle flaxseed. In contrast, the hexanal and rancid sensory scores were higher in breads made with the <600 µm particle flaxseed. Overall, the breads made with the 850 µm and 600 µm flaxseed particles had slightly better quality than breads made with the mixed particles and <600 µm particle flaxseed during the 7 day storage. We recommend that 850 µm or 600 µm flaxseed particles be used in breads based on bread quality parameters.