175 Determination of optimum milling conditions for the Chopin CD-1 mill.

B. PASZCZYNSKA, Z. Czuchajowska, and B.-K. Baik. Department of Food Science and Human Nutrition, Washington State University, Pullman, WA 99164-6376.

Milling conditions for the Chopin CD-1 mill, with which a minimum of 25g wheat can be milled, were optimized using one hard red spring (HRS) and one soft white winter (SWW) wheat grown in the Pacific Northwest. Effects of milling frequency on roll temperature and flour yield, as well as effects of tempering time, moisture and sample size on flour yield, ash content, protein content and starch damage were evaluated. Using 500g wheat samples, both roll temperature and flour yield were stabilized with 6 times of milling. With 17.5% tempering moisture, increasing tempering time from 24 hr to 48 hr resulted in no change in flour yield in either hard or soft wheat. No changes in ash content of hard wheat was observed, but in soft wheat ash content decreased from 0.632% to 0.601%. Total flour protein content in both hard and soft wheat increased. Starch damage in hard wheat was less, but in soft wheat starch damage was more severe. When tempering moisture was raised from 16.0% to 17.5% in hard wheat and from 14.0% to 16.5% in soft wheat, flour yield increased from 57.9 to 60.5% in hard wheat and from 65.4 to 67.4% in soft wheat. Lower flour ash content (0.59 to 0.58% in hard and 0.57 to 0.55% in soft wheat) were observed. In addition, there was a lower protein content in hard wheat. Sample size for milling also has a large effect on yield, ash and protein content of flours. Lowering the sample size from 500 to 50g resulted in less than 4% decrease in flour yield in both soft and hard wheat.