Tuesday, June 4, 2013

that simple loaf of bread?

Wheat harvest is upon us and in this moment-- pre harvest-- if feels as if the dice are suspended in the air and we-- the farmer, miller, and baker-- are simply waiting for them to land. 

What do we millers and bakers hope for? Quality wheat with good baking performance! 

But what quality characteristics equate to good baking performance and how is the miller to determine if a lot of wheat deems worthy of purchasing from a farmer?

To begin with, on the farmer’s end-- beyond yield-- the first measure of his/or her grain is test weight. Test weight is a good overall indicator to both farmer and miller as to the quality of the wheat, as it measures the density-- or how filled out the grain kernel is. It also may indicate-- if low test weight is detected-- the presence of diseased kernels. Grain is accounted for in bushels, which is a volume measurement, and a bushel of wheat is about 60 lbs (though this may vary a bit with the variety). In general, 56 lb. test weight of unclean grain is the minimum acceptable test weight for a miller. Low test weight can be caused by poor growing conditions, disease, or sprout damage. Cleaning grain, especially running it over a gravity table, can increase test weight by vetting damaged and diseased kernels.

The next test a farmer’s grain must undergo is testing for mycotoxin deoxinivalenol (DON), also known as vomitoxin. DON (or vomitoxin) is caused by the Fusarium fungus commonly known as head blight. Cool wet weather around flowering time can threaten even an extraordinary stand of wheat. High levels of vomitoxin can be visibly detected in a field by a pink hue over the crop. When ingested, high levels can cause vomiting and diarrhea in humans and livestock. The FDA has set a maximum DON guideline of 1ppm for human consumption, but to many a miller the acceptable threshold for organic human food grains is essentially zero. On the farm end, if Fusarium is identified, the grower can reduce levels in a crop by turning the air up on his or/her combine at harvest to blow out the lighter, diseased kernels. Post harvest, the grain should be cleaned well, especially run over a gravity table. Good crop rotations and seeking resistant varieties of wheat can also help alleviate future disease pressure. And of course, hopes and prayers for good weather never hurt.

Yet another test wheat is subjected to if said crop hopes to land with a miller (and into a loaf of bread) is falling numbers. A falling numbers test determines the level of enzymatic activity in a lot of grain, and in doing so indicates whether there has been (pre harvest) sprout damage to the crop. Heavy sprout damage can be extremely problematic to the baker, as flour made with this grain will have reduced mixing strength, produce sticky dough, and affect a loaf’s volume and shelf life. A small amount of heavily sprouted grain-- as low as 5%-- mixed with a lot of sound grain may deem the whole lot unacceptable for a baker. 
On the farm end, sprout damage becomes a threat with the onset of wet weather around harvest. Certain varieties of wheat are more susceptible than others, with white wheats being more susceptible than red wheats. 
The falling numbers test measures the number of seconds a plunger takes to fall through a slurry of flour. The less viscous the slurry, the greater the enzymatic activity (the enzyme-- alpha-amylase-- is starch degrading) and the quicker the plunger will fall. (High enzymatic activity is the indicator of the sprouting process, btw.) The falling number is the number of seconds the plunger takes to fall. Falling numbers of 300 and above are deemed sound wheat. 200 and below are unacceptable for a mill.  Somewhere in the range of 250 to 300 are usually the minimums set by flour mills. 

And still more tests! The baker needs quality protein. Gliadins and glutenins are the gluten-forming proteins in wheat that enable the baker to make a leavened, lofty, loaf of bread. These proteins provide the extensibility and elasticity to dough. While testing for protein in wheat does provide a measurement of wheat’s quality, it is still quite possible to have a high protein number and yet poor quality wheat or the other way around-- a low pro number with high quality performance. The protein number is somewhat one dimensional and so without a bake test and/or the use of a farinograph (lab equipment which measures extensibility, elasticity, and water absorption of dough) it is difficult to fully determine the quality of wheat. Although diverse crop rotations aimed at building soil fertility, well timed field application of nutrients, seed variety choice, and good weather all factor in when it comes to producing a quality crop of wheat.

And lest we forget the quality of the baker. From the miller's end, we can convey part of the story--what we received from the grower (the falling numbers, protein, test weight, hardness), the variety that was planted, who grew it and where-- and how and when it was milled. But we leave it to the baker to engage with their flour. Each baker will approach his or her dough differently-- fermentation times vary as do mix times, leavenings, and ovens. The baker too will interact with the weather-- ambient humidity, heat, cold -- and with each season, a new crop. 

And so that simple loaf of bread-- of wheat, water, and sea salt; sun, soil, and rain-- is not so simple after all. 

from the ground up,
jennifer lapidus