WASHINGTON — Flour production by U.S. mills in the second quarter of 2010 totaled 100,630,000 cwts, down 2.2% from 102,926,000 cwts in the same quarter of the preceding year, according to preliminary data compiled by the U.S. Commerce Department’s Bureau of the Census. April-June production also was down 1.7% from the 102,319,000 cwts recorded in January-March, reversing the usual rise from the first to second quarter. Rate of grind in the second quarter fell to 84.9% of six-day grind, the lowest in four years, or since April-June 2006 when it was also 84.9%. In the second quarter of 2009, mills ran at 87.2%. The 24-hour capacity of U.S. mills was 1,540,000 cwts, up 4,000 from the first quarter and 6,000 over a year back. A major contributor to the overall flour production decrease was semolina output, totaling 7,542,000 cwts, down 6.1% from 8,030,000 a year ago. U.S. flour output in the first six months, or January-June 2010, aggregated 202,949,000 cwts, down 0.3% from 203,588,000 in the same period of 2009.