Ag Instructor Vic Martin: What’s In a Kernel of Wheat?

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June 13, 2021

As of June 8, the Drought Monitor reports no changes from last week with only abnormally dry conditions in small patches in NE and SE Kansas.  However, this hot spell will start to deplete soil moisture a bit.  On the positive side, while uncomfortable for us, the high humidity helps decrease plant water usage.  The six to ten-day outlook (June 15 to 19) indicates well above normal temperatures and below-normal precipitation.  The eight to 14-day outlook (June 17 to June 23) indicates more of the same.  This will speed up wheat maturation and allow for remaining full-season crops to be planted. 

Wheat harvest will be later than normal this year which isn’t a bad thing as the wheat crops had a good opportunity to develop and ripen normally.  But, how many really know what makes up a wheat kernel, or berry?

  • First there are six classes of wheat: hard red winter wheat, hard red spring wheat, soft red winter wheat, soft white, hard white, and durum.  All seeds are composed of the same three main parts with the differences being things like protein content and in the case of red vs, white wheat it’s the presence (red) or the absence (white) of tannins.
  • All wheat kernels are composed of the endosperm, the germ, and the bran.  So what composes each of these components?
  • The endosperm typically makes up about 80% of the kernel and makes up the biggest part of flour.  The endosperm is composed of protein and carbohydrates (starch). 
  • The germ is only around two percent of the seed weight and is the fertilized egg, the embryo that will produce a wheat plant.  It is often removed when producing flour as the fat content can reduce shelf life.
  • The bran typically makes up around fifteen percent of the kernel.  It is included in whole wheat flours but removed for short patent flours. The bran is essentially the seed coat and is what gives our red wheat its color and is composed of tannins. These tannins give whole wheat flour a different flavor that many cultures don’t prefer. 
  • As already stated there are six classes of wheat.  The ones that matter most to you the consumer are red vs. white and hard vs. soft.
  • Red vs. white – as stated previously the red in the bran is from tannins.  The same compounds that give red wine its more acidic, tart flavor.  Unless you use whole wheat flour, the bran is removed.  Red whole wheat flour has a much different flavor many don’t like in the US and around the world.  That is where white wheat comes in as its lack of tannins makes a “better tasting” whole wheat flour and much of the world uses whole wheat flour.  The Pacific Northwest and Australia produce white wheat almost exclusively for the Asian flour market.
  • Hard vs. soft – this has to do with gluten.  Gluten is a type of protein found in cereal grains, especially wheat.  High gluten levels make the dough elastic.  Hard wheats have a higher gluten (protein) content and soft wheats a lower content.  This changes what they are best for.  All-purpose flour is a mixture of the two types.  Soft wheats are typically used in cakes and pastries.  Hard wheats are used in bread, buns, hard rolls, etc.
  • One last thing, durum wheat is the highest in protein and used here in pasta and some breads, including flatbreads.