The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Properties of 'young' or 'green' flour in finished sourdough loaf

perk's picture

Properties of 'young' or 'green' flour in finished sourdough loaf

Loaves will occasionally finish with a grassy smell and lighter color, not the full on rich coloring we typically get in the crust nor the full, nutty smell. Our head baker believes this is due to 'young' wheat.

Has anyone else experienced a similar occurrence when their flour varies? If so, can you elaborate on whether this is because the wheat was harvested too early or something was inconsistent in the milling process? 

My assumption: wheat harvested too early yields the grassy smell because the amino acid (or lactic acid?) content is too high. Total shot in the dark. But just thinking about the reaction that occurs between amino acids and sugars when browning foods. 

In my research, I've found a lot of commentary on smell as a result of harvesting methods, what the wheat was contained in, etc. Nothing on the actual age of the wheat or other wheat properties that might drive this aroma and smell. 

Any tips would be greatly appreciated!

Norcalbaker's picture

wheat flour. Physiological mature has to be reached for successful harvesting, drying, and storage. Farmers won't harvest if there's no indication of physiological maturity. Aside from visual inspection of the crop, farmers determine physiological maturity on moisture content.

As grain matures, it loses moisture. The high moisture level in immature grain makes it susceptible to spoilage; increases drying and storage costs; produces an inferior grain. There's really no incentive to harvest early. I think the only reason a farmer would harvest a bit early is if a heavy rain was forecast in the few days leading up to the harvest.  Even then, the harvest would be extremely close to the moisture  thresholds.

A late harvest isn't good either. Overly dry grain is very fragile, thus easily damaged during harvesting. So moisture less than 14% results in smaller yields.

The maturity moisture level for harvest is a very tight window: 20% - 14%. Most wheat is harvested between 20% - 18%.

I think the "grassy" aroma is due to the variety, region, and milling.

No doubt higher extraction flour has more flavor. But a study published by scientists at the University of Copenhagen found wheat variety determines aroma and final flavor. They found five aroma descriptors associated with the endosperm: maize, bean shoots, chamomile, umani, and fresh grass.  

Interestingly, they found five totally different set of descriptors associated the wheat bran.

 p.s. I believe the study was published in the journal of Food Science and Technolog.

perk's picture

Thanks for your insights @norcal. Very helpful (here's the report you reference in case others are interested  -

@norcal do you have any hunches on the lighter coloring? Aside from possible variations in steps from mixing to baking.

We did recently have a very significant rain event (cyclone), which could have prompted harvesting earlier than planned. But I also haven't checked when these bags were processed.

Norcalbaker's picture

Where just the flour is concerned, the two major factors in color are the carotenoid pigments in the endosperm and ash content.

The level of pigment in the endosperm is a genetic determination. But pigmentation is also altered to some degree crop by crop due to cultivation conditions and bleaching. Flour doesn't have to be bleached to lose some pigmentation. Unbleached flour will oxide and lose some pigmentation in storage. So the amount of pigment in any given lot will vary based on genetics, cultivation, and storage conditions.

Ash content also effects color. Ash is complex because it's not just the micro-region that effects the type and amount of minerals in the wheat, but the milling process. When we talk about ash content in flour, we focus on the mineral levels. But I think it's important to keep in mind that the ash is in non-endosperm parts of the wheat kernel.

So higher ash content also means a higher amount of contamination of non-endosperm parts in the flour. Too much contamination will adversely effect the performance of the flour. But too clean an extraction will give bread--or any baked good, a lighter color.  So you can start with a high ash kernel, but the ash can be reduced due to milling.

Protein, ash, and moisture are the three characteristics that are considered vital measures for flour quality. Moisture is the easier of the three to control. Protein and ash will vary greatly region by region, field by field, crop by crop.

Consistently in the quality of your bread, or ant baked good, depends in part on a designated supplier that maintains a relationship with mills and farmers committed to specific quality standards.  Example is Central Milling.  The farmers and mill have an unwavering commitment to their products and business relationship.  When the price of wheat skyrocketed the farmers could have sold for huge profits on the open market.  Instead, they chose to sell their grain to Central Milling in keeping with their business values and commitment.

pmccool's picture

In doing some reading recently on the topic of 'green' flour, I came across some interesting observations that the length of time in storage for the wheat, between harvest and milling, has an impact on flour performance in bread.  This was new information for me, since I don't ordinarily spend much time (essentially zero) looking at technical milling treatises.  Apparently the flour from wheat kernels that are several months removed from harvest is better in baked goods, performance-wise, than flour made from recently harvested wheat.  I didn't happen to find anything that talked about the 'why' behind this phenomenon although it is apparently not a function of moisture content.

Yet another variable in the whole process from field to table and one that a home baker really has no way to identify or control for.  This is the kind of thing that requires us to exercise the art of baking, as well as technical nastery.


drogon's picture

... if the loaves are just slightly underbaked. Variations on oven temperature or time?

I find tht the stoneground flour I buy almost always has a bit of a grass field smell about it (especially some of the hertitage varietys) but I've never noticed it in the finished loaves.

I will often leave my loaves in the oven for another minute or 2 if I think they're a bit beige.