Last week, I made chocolate chip peanut putter cookies except that I substituted sunflower seed butter for peanut butter. It is one of my favorite cookie recipes, and I was looking for a way to use up the rest of my sunflower seed butter (see my post on the nut butter taste-cost tradeoff).
My kids and I ate a few cookies soon after the cookies came out of the oven. A few hours later when the cookies cooled, the insides of the cookies turned a brilliant shade of green. The cookies still tasted fresh and delicious.
An interesting discussion of chemistry ensued. A post on O Chef discusses the chemical reaction that turned my cookies green:
All plants contain chlorogenic acid, mostly in the stems and leaves, but sunflowers also have it in the seeds. A spokeswoman for Red River Commodities says that SunButter does indeed turn cookies and other baked products green as they cool. The solution, she says, is to reduce the amount of baking soda or baking powder in your recipe by almost half, which balances the acidity of the ingredients and keeps them from changing color.
My brother has a PhD in chemistry and offered some feedback. For full disclosure, he is not an expert on the chemistry of cookies, but he knows his stuff.
Well, I hate to disappoint, but I neither know the answer nor any food chemists who may. Luckily the ochef link gives some hints: chlorogenic acid (which is NOT chlorophyll – as on sunbutter’s FAQ section) was implicated and that the pH is important.
I think it is reasonable to assume that oxidation is the cause of the color change as this can be a slow process (thanks to the activation energies, which saves us from burning). Rates of oxidation can be affected by pH, which can explain the effects of adding baking powder, which contains sodium bicarbonate (a base) and lemon juice (an acidic solution) mitigate the color formation. However, lemon juice contains vitamin C, which in addition to being an acid is a strong reducing agent (anti-oxidant). Neither vitamin C nor its oxidation product will absorb light in the visible region and therefore aren’t expected to produce color. Chlorogenic acid will absorb light, but well into the UV region and not the visible region. It is possible that one of its oxidation products does.
But to be honest, I have no idea what all of the ingredients are in sunbutter or how it is processed so I cannot say exactly what is the source of the green color. Chlorogenic acid is a possibility, but there certainly are plenty of other chemicals in the sunbutter that could potentially produce the color as well.
My family and I survived eating the green cookies, so I am confident that we were exposed to an innocent chemical reaction, not botulism or flesh-eating bacteria.
Update on 12/9/2013 from my brother:
I am not an expert in food chemistry, but I can provide some insight. I will address some of your questions below:
Molecular oxygen (O2) is not a good oxidant at the temperatures that we typically encounter, which is great, otherwise we would all catch fire. The reason we don’t is because of the activation energy required for oxygen to burn materials. However, at elevated temperatures (like in a fire or an oven) oxygen will react with many materials, often uncontrollably.
Another way oxygen can react with materials at lower temperatures is by being activated. In the body, this is done by enzymes, which catalyze many reactions that otherwise wouldn’t occur under the conditions (in the case of in the body, often temperature is the limitation). In fact, oxygen is involved in many reduction-oxidation pathways (redox) necessary for life. However, there are some other pathways that can cause deleterious side-effects, namely by forming reactive oxygen species (ROS). Here are a few links, which explain it:
http://www.rndsystems.com/mini_review_detail_objectname_MR97_ROS.aspx
http://www.biotek.com/resources/articles/reactive-oxygen-species.html
As for what is happening in the cookie, I cannot say for sure. Oxidation is often attenuated by pH. Baking soda contains a weak base, sodium bicarbonate (NaHCO3).
Chlorogenic acid is also a reductant. So while heating in the presence of oxygen, it will likely be oxidized. In the wikipedia article, it mentions that it turns green when oxidized:
http://en.wikipedia.org/wiki/Chlorogenic_acid
It is possible that some oils, or certainly the seeds, which are not refined contain much of the chlorogenic acid (assuming that it is the source of the green color). Changing the pH (by adding acids like lemon juice, or bases like NaHCO3) could change the oxidation potential of the chlorogenic acid and give variable amounts of color in baked products.
Cargill is a major supplier of vegetable oils. They typically refine their oils:
https://cpo.cargill.com/processes/vegoil.shtml
I hope this information helps.
This entry was posted on Thursday, March 22nd, 2012 at 7:45 am and tagged with chemistry, cooking and posted in Uncategorized.You can follow any responses to this entry through the RSS 2.0 feed.
FAQs
The greening observed in the cookies results from the alkaline conditions caused by high pH ingredients (baking soda and maple syrup), favouring oxidation of CGA in the sunflower seed butter and subsequently reacting with amino acids (Bongartz et al., 2016).
Why did my cookies turn green? ›
The chlorogenic acid (chlorophyll) in sunflower seeds reacts with the baking soda/powder when baked, causing the green color when the cookies cool. This is completely harmless! Depending on the recipe, a splash of lemon juice may help. You can also check out our tried and tested SunButter recipes.
Why are there green spots on my cookies? ›
THE BOTTOM LINE: Sunflower butter may sometimes create a green color in baked goods. The baked goods taste fine and are perfectly safe to eat—the color comes from the chlorophyll present in sunflower butter.
What turns green when baked? ›
Something weird happens when you take sunflower seeds and heat them with some baking soda. sunflower seeds contain all kinds of healthy fats, proteins and anti-oxidants. and they also contain chlorogenic acid. which reacts with the baking soda and air to form a brilliant blue green pigment.
Why do my cookies have a chemical taste? ›
Remember also that too much baking soda in a recipe and not enough acid will still result in a soapy, metallic taste in the baked good. Thus, getting the right amount of baking soda in your baking is important, we don't want soapy tasting cakes!
Why do cookies change color? ›
Sugar caramelizes.
The edges and bottom of the cookie, the hottest areas of the cookie, begin to brown as sugar granules melt together and caramelize.
Does baking soda turn things green? ›
Our answer. The green flecks are carrot but the colour has been changed by the bicarbonate of soda (baking soda) in the mixture. Some pigments are sensitive to pH balances and will change colour if they are in a very acid or very alkaline environment.
Why did my banana muffins turn green? ›
Low and behold the acidic component is in bananas, so any excess baking soda that doesn't help the banana bread rise will react, hence green or blue banana bread slices the next day. Oh and too much baking soda leaves a metallic aftertaste.
What do overcooked cookies look like? ›
If the edges are dark brown or black, you've overcooked them. On the other hand, if they're pale without a honey-brown tinge, they're not ready yet. A set surface - A well-done chocolate chip cookie will have a set, slightly firm upper surface. If the surface is rock-hard, the biscuit is overcooked.
What does it mean when bread turns green? ›
Green mold is an umbrella term that refers to different species of fungi that grow in shades of green. It appears soft and fuzzy or powdery and can have different hues of green. You may have seen green mold on fruits, bread, and many other foods. However, green mold can also grow in wet areas of a home.
When blue food coloring is added to this yellow base, the batter turns green. Moreover, food coloring is known to darken. This means that as the cake bakes, its emerald tinge will become even more apparent. Thankfully, there are measures you can take in order to avoid green baked goods.
Why did my blueberry muffins turn green? ›
Blueberry Baking Chemistry
Blueberries turn greenish-blue in a batter that has too much baking soda (or grey in a smoothie with a lot of dairy), which creates an alkaline environment. That's why mixing a little lemon juice into your batter or smoothie will give you a more vibrant color.
Why does food turn green? ›
In raw form, the green chloroplasts in vegetables are clouded by pockets of gas filling the space between the plant's cells. When the vegetable starts to heat up, those air pockets expand and break away – leaving the way clear for us to see the pure, unfiltered green!
What happens to cookies with too much baking soda? ›
Using too much baking soda or baking powder can really mess up a recipe, causing it to rise uncontrollably and taste terrible. But don't freak out if you accidentally poured too much baking soda in cookie dough or added too much baking powder to cake batter. Depending on the situation, you might be able to fix it.
What happens if you put too much baking powder? ›
Too much baking powder can cause the batter to be bitter tasting. It can also cause the batter to rise rapidly and then collapse. (i.e. The air bubbles in the batter grow too large and break causing the batter to fall.) Cakes will have a coarse, fragile crumb with a fallen center.
How do you get rid of chemical taste in food? ›
Regularly brushing and flossing your teeth may help with dysgeusia or keep it from happening. Rinse your mouth before meals. Rinsing your mouth with a solution of baking soda and water neutralizes acid in your mouth so what you eat tastes like it should.
How do you know if cookies have gone bad? ›
Off Smell or Taste: Any rancid, sour, or just "off" smell or taste is a clear indicator that cookies have gone bad. Mold: This is a definite sign of spoilage. If you see any mold, the cookies should be discarded immediately.
Can cookies become moldy? ›
When cookies are exposed to humid environments or stored improperly, moisture can accumulate, creating an ideal breeding ground for mold. Additionally, airborne mold spores can settle on the surface of cookies, initiating mold growth under favorable conditions.
Can cookies be spoiled? ›
Signs Your Cookies Have Gone Bad
While cookies can last quite a while, it's essential to know the signs that indicate they may have gone bad. Here are some common indicators: Off Odor: If your cookies emit an unpleasant or rancid odor, it's a clear sign that they have spoiled.
Can bacteria grow on cookies? ›
Beuchat and study co-author David Mann, a research professional in the center, found that not only can harmful bacteria survive in dry foods, like cookie and cracker sandwiches, but they can also live for long periods of time.
