Milling Journal - Q4 2008 - (Page 12) effects of the treatment are much more important than interactions between treatments, and final moisture far and away had the biggest effect on yield. Table 2 on page 10 shows a very different result, however, when looking at the effect of various tempering factors on starch damage and gluten strength. (Starch damage was measured using a sodium carbonate solvent retention capacity test.) Here, the interactions between treatments were more important in determining starch damage and gluten strength than individual treatments. Table 3 above looks more closely at the changes in flour yield and quality as tempering moisture increases. Increasing the initial tempering moisture reduced flour yield and starch damage, but increased flour gluten strength and pentosan content. (Pentosans, found in plant cell walls, are one of the main compounds influencing how much water needs to be added to a flour to form a dough.) Reducing tempering time, reducing the initial grain moisture, or increasing tempering temperature also reduced flour yield and changed flour quality in a similar pattern to changing the final tempering moisture. Reducing initial tempering moisture increased flour yield while increasing starch damage. Increasing the final tempering moisture reduced both flour yield and starch damage. Other combinations of tempering with 15% final moisture improved yield with a minimal increase in starch damage. Reducing the initial tempering moisture also increased flour yield while reducing gluten strength. Increasing the final tempering moisture in this test reduced flour yield while increasing gluten strength. Other combinations of tempering with 15% final moisture improved yield with a minimal reduction in gluten strength. Finally, in comparisons between flour yield and pentosan content, reducing initial tempering moisture increased flour moisture while reducing flour pentosan content. The different response of total flour yield and flour quality, especially at 15% final grain moisture, may provide millers an opportunity to adjust flour quality through tempering. Edward Souza Research Director USDA Agricultural Research Service Conclusions The researchers concluded that total flour yield is very responsive to tempering treatments. The different response of total flour yield and flour quality, especially at 15% final grain moisture, may provide millers an opportunity to adjust flour quality through tempering. A question remaining to be answered is why starch damage and pentosan content respond differently to tempering. The studies also noted that changing cultivars changed flour yield to a much larger extent than changing tempering practices. Research remains to be done to determine whether there are better ways to capture advantages from these differences. Ed Zdrojewski, senior editor 12 Fourth Quarter 2008 Response No. 121 MILLING JOURNAL
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