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September 23, 2004 Delayed Harvest of Small Grains and Quality Concerns
The small grain harvest has been delayed beyond the optimum this year due to the cool wet weather of August and September. In addition to concerns about losses due to shattering and lodging, there are also concerns about grain quality as harvesting is delayed. Sprouting, low falling numbers and bleaching can significantly diminish the value of a standing grain crop. Several elevators have reported receiving sprout damaged wheat and some elevators have started to routinely test falling numbers for the wheat that is being delivered. Sprout damaged wheat and barley pose real problems for the industry and, because of these problems, local elevators will steeply discount sprouted grain. The potential for sprout damage is influenced by the age of the crop, the environment and the variety grown. Pre-harvest sprouting does not occur until the kernels have fully matured and have undergone a period of “ripening,” after which repeated rains and prolonged periods of dew can initiate germination. Varieties differ in their propensity to sprout with varieties like Hanna, Norpro, Dapps, Parshall and Alsen being the most resistant to pre-harvest sprouting and Dandy, Mercury and Ingot being the most susceptible (see Wiersma, 2004 http://www.extension.umn.edu/cropenews/2004/04MNCN18.htm for more details on varietal difference). The process of germination begins when enzymes in the kernel become active and degrade it into simpler molecules used for seedling growth. The grain industry uses the falling number test to determine sprout damage in cereal grains. This test gives an indication of the level of alpha-amylase (starch degrading) enzyme activity in a sample of grain or flour. The wheat industry typically considers falling number values over 300 seconds to be a sound crop, while values below 300 are often discounted. Low falling number values are possible even if there are no visible signs of germination, due to the presence of these enzymes. For more detail on the falling number test see the article in the NDSU Small Grains Web site at http://www.ag.ndsu.nodak.edu/aginfo/smgrains/. Preharvest sprouting lowers test weight and flour yield, lowering the grade and value to the processor. The impact on baking quality is observed by lower absorption (water added in baking, which reduces bread yield), reduced mixing strength and tolerance, and sticky dough. It can also affect loaf volume, crust strength and crumb texture, whereas a wet and gummy crumb causes problems with slicing and shelf life. It also reduces the quality of Asian noodles. The effects on durum are lower test weight, reduced semolina yield and what color. In the processing of semolina and pasta, sprouting increases semolina speck counts, reduces shelf life of dried pasta (due to checking or cracking), increases cooking loss, and produces softer cooked pasta. ### Source:
Brian Sorenson, (701) 231-6048, brian.sorenson@ndsu.nodak.edu
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North Dakota State University |
