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Category: Food (Page 1 of 6)

Foods and Cooking.

Our Favorite Things are Aldehydes


Aldehydes and Allergies

Aldehydes are so common and important in our lives that it’s good to know something about them. The flavor of vanilla, almond, cinnamon, and many others result from aldehydes. Aldehydes are a family of chemicals that are common in nature and foods, and important in industry. I knew that artificial vanilla and almond flavorings posed little danger to people with nut allergies. But the question came up in a discussion and I decided to find out if what I knew was, in fact, correct. (It is.) In the process of researching this, I fell down a rabbit hole of fascinating information, learned a number of interesting things related to chemistry and food chemistry, and collected it here in this article.

There is a family of chemicals called aldehydes that are extremely useful to plants and industry. It’s called a “family” because aldehydes have a common core molecular structure with an open bond to which various molecules can be attached that give various effects.

One thing aldehydes have in common is they have strong and distinctive odors. Another thing in common is that most of them are toxic in sufficient concentration. (Concentration is key here. At low concentrations, most of them are harmless.) I expect you are already familiar with or have heard of several of the aldehydes I’ll mention.

Formaldehyde

The one I’ll mention first is not closely related to foods but is one you’ve almost certainly heard of. Formaldehyde1 is a critically important chemical in many industries including plastics manufacturing, fibers, and adhesives. Some of the best and strongest waterproof glues are based on formaldehyde. Formaldehyde is a disinfectant and is used to preserve biological specimens. In biology class you may have seen specimens or body parts preserved in jars. Those were likely filled with formaldehyde as a preservative. Formaldehyde is toxic2 and carcinogenic in sufficient concentration. It’s produced in small amounts by most organisms, including humans.

You’ve all smelled it. It’s a key ingredient in “new car smell”, “new carpet smell”, and “newly constructed house smell”. Our noses are sensitive to aldehydes so very low concentrations are detectable.

Acetaldehyde

The next one is acetaldehyde.3

This one is produced by plants and occurs in bread, coffee, and ripe or overripe fruit, and is a component in the fragrance of wine and the smell of smoke. Acetaldehyde4 is formed from the oxidation of ethanol. It forms in the bloodstream after drinking alcohol and is partly responsible for hangovers.

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Plants discovered the value of aldehydes a long time ago. When nature discovers a chemical that provides two unrelated benefits for the price of one, it’s a definite keeper. Aldehydes are such chemicals. Some of the most important flavors in foods result from aldehydes.

Vanilla

Vanillin5 is a member of the benzaldehyde family of aldehydes and is the chemical responsible for the flavor and fragrance of vanilla. It makes the seed pod of the vanilla orchid attractive to birds and animals and is an insecticide. Two functions for the price of one. Unlike most aldehydes, vanillin has low toxicity and is classed as merely an irritant.6

Vanilla has been in use in the Americas for at least 4,000 years. It was brought to Europe by Spanish explorers in the 1500s.

Cinnamaldehyde

The odor and flavor of cinnamon comes from an aldehyde that’s found in the bark of the cinnamon tree and various others where it serves as an insecticide. Cinnamaldehyde7 is a pale viscous liquid that functions as an anti-bacterial, anti-fungal, and is a potent repellent and killer of Aedes mosquitos. Like vanillin, cinnamaldehyde has low toxicity and is classed as merely an irritant.8

At high humidity and temperature, cinnamaldehyde decomposes to styrene. This is why cinnamon always contains a small amount of styrene.

Benzaldehyde9

This is the aldehyde that gives almonds their flavor.

It also occurs in certain fruits and the pits of peaches, apricots, apples, and cherries. It makes the fruit more attractive to animals and is an insecticide. It’s frequently used by bee keepers as a bee repellent. The odor causes bees to leave the hive while honey is collected after which they return to the hive.

Benzaldehyde is the simplest of all the aldehydes consisting of a benzene ring attached to the open bond of the aldehyde molecule. Benzaldehyde is classed as an irritant.10

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Vanillin, cinnamaldehyde, and benzaldehyde are chemically classed as merely irritants. Technically all three are toxic in sufficient concentration, but so is water. To reach dangerous levels you’d have to consume absurdly large amounts. In the case of almond extract, you’d die of alcohol poisoning long before reaching dangerous levels of benzaldehyde.

The key here is concentration. Human noses are quite sensitive to aldehydes so for flavoring only a tiny amount is needed. Since most kitchens lack the ability to measure microgram quantities, these extracts are heavily diluted with alcohol so useful amounts can be measured with a teaspoon. At levels used for food flavoring there is some evidence these compounds provide anticarcinogenic effects.11

These aldehydes can all be synthesized in the laboratory or made inexpensively at industrial scale. There is no difference between vanillin made by an orchid and chemically produced vanillin. The same is true for benzaldehyde. If anything, the synthetic version gives a purer more consistent flavor note because it’s pure and not complicated by myriad other chemicals that vary from plant to plant.

Cilantro

The flavor of cilantro derives from several substances, some of which are aldehydes. Some people perceive the flavor of cilantro as a refreshing lemony-lime but some perceive it as tasting like soap or something rotten. It was found that 80 percent of identical twins had the same perception of cilantro but only 50 percent of fraternal twins did. This implied a genetic cause. Today the gene(s)12 have been identified. It’s believed that those who like cilantro are unable to detect one or more of the aldehydes in cilantro.

Furfural

Furfural is an aldehyde that results from the dehydration of sugars. It occurs in agricultural by-products like corncobs, oat bran, oat hulls, wheat bran, and sugarcane bagasse. It’s a common ingredient in processed foods and beverages. It commonly appears in many cooked or heated foods.

Furfural13 is classed as acutely toxic, an irritant, and health hazard.14

It’s dangerous to the skin. NIOSH permissible level is 5 ppm. 100 ppm is considered an immediate danger. Furfural is lethal to rats and dogs at concentrations of 200 to 1000 ppm. It’s flammable and explosive when mixed with air. It has a penetrating odor reminiscent of almonds. There is no data on human subjects.

Retinaldehyde

The importance of aldehydes cannot be overstated. Retinaldehyde15 is found in meats and is the chemical basis of our eye’s ability to sense light. Another name for it is Vitamin A aldehyde. Vertebrates acquire it directly from eating meat or can also synthesize it from carotenoids. In higher concentrations it’s classed as an irritant and a health hazard.16

Glycolaldehyde

This aldehyde is believed to play an important role in the formation of the chemical building blocks of life.17

Interestingly, radio astronomy has detected glycolaldehyde in interstellar space. It’s also been identified in Comet Lovejoy, along with ethanol. This aldehyde is classed as an irritant, highly reactive, and is a common metabolite produced by living things ranging from bacteria to humans.

Lily Aldehyde / Lysmeral / Lilial

Lily aldehyde18 has a strong floral odor reminiscent of lily of the valley. Thousands of tons are produced each year for use in perfumes and detergents.

It’s classed as a health hazard,19 found to be harmful to fertility, and is banned in the EU since March 2022.

Citral

If you’ve made it this far in this article, you can probably guess from the name that citral20 is the aldehyde primarily responsible for the fragrance of citrus fruits like lemon, lime, etc.

Citral is found to have a pheromonal effect on acari and insects. Chemically, it’s classified as an irritant.21

It’s a component in the oils of several plants, as follows.

Lemon myrtle (90–98%)
Litsea citrata (90%)
Litsea cubeba (70–85%)
Lemongrass (65–85%)
Lemon tea-tree (70–80%)
Ocimum gratissimum (66.5%)
Lindera citriodora (about 65%)
Calypranthes parriculata (about 62%)
Australian ginger (51-71%)
Petitgrain (36%)
Lemon verbena (30–35%)
Lemon ironbark (26%)
Lemon balm (11%)
Lime (6–9%)
Lemon (2–5%)

Citronellal

Citronellal is the aldehyde that gives citronella its lemony scent. Citronella22 is an insect repellent. Research has shown it to be highly effective at repelling mosquitos and is a strong antifungal.

Chemically, it’s classed as corrosive, an irritant, a health hazard, and environmental hazard.23

Allergies

Lastly, we come to allergies, specifically allergies to benzaldehyde or vanillin. It’s possible for a human to develop an allergy to almost anything, even metals like nickel. The good news is that it’s rare for someone to be allergic to these two aldehydes that are such important flavors.

The vast majority of allergies, whether it’s to pollen, animal dander, fish, shellfish, bee stings, whatever, are allergic reactions to proteins found in those things.

Natural almond extract is made by steaming almonds in a pressurized vat, then extracting the almond oil. This liquid includes not just benzaldehyde but many other chemicals including proteins. These proteins are usually what a person with a nut allergy reacts to.

Genuine vanilla also contains many chemicals from the plant besides vanillin.

Artificial almond extract consists of a small amount of synthetic benzaldehyde diluted with ethanol. Neither has been anywhere near an almond tree and it contains no proteins or anything else. The same is true for artificial vanilla.

The concentration is chosen to match the flavoring power of genuine almond or genuine vanilla extract so the artificial is interchangeable with the genuine in recipes.

Fortunately, this means that those with nut allergies are almost sure to be safe with artificial almond or vanilla flavoring. Even so, if you have a nut allergy, especially a bad case, you should check with your doctor / allergist. They will be able to specifically test whether you are allergic to benzaldehyde (unlikely) or to the dozens of other compounds in nuts.

As a final note, a significant number of children and adults test positive for allergy to cilantro but only a few exhibit symptoms. For those who do, the symptoms can be severe.

Provisioning for Thanksgiving


Are you planning to host a Thanksgiving dinner? Do you know how much food to buy? Planning out a Thanksgiving dinner can be challenging. Since the Thanksgiving holiday is about plenty, you want to avoid running short. This can lead to making way too much food and eating leftovers for two weeks. Below are a few tips to help you.

I’m a retired engineer. I switched to the food preparation business ten years ago and can’t help but bring my engineering mindset with me. I study and learn every technique I can and study the chemistry of cooking. While I frequently cook things that I make up on the spot, for anything serious I like to have numbers and measurements. Below are some numbers you can use.

A Thanksgiving Spread

Turkey: 1 pound of bird (uncooked) per person, and you will have leftovers.

Dry mix stuffing like Stove-Top: 1 ounce dry mix per person

Potatoes for mashing: 6 oz (raw) per person or 3/4 of a large potato

Sweet potatoes: 6 oz (raw) per person

Canned cranberry sauce: 4 oz per person

Pie: 1 piece per person

Butternut squash: 7 oz (raw whole squash) per person

Brussels sprouts: 2.5 oz (raw) per person

Green beans: 4 oz (canned) per person

Extending the Above to 40 Persons

To extend the above numbers, multiply by the number of guests and round up to the next package size. Thanksgiving usually involves a lot of baking. If you try to prepare all the food on Thanksgiving day, you’ll need several ovens. Remember that cooking the turkeys will occupy your oven(s) for much of the day. Prepare as much as you can the day(s) before and reheat it.

Of course, you don’t have to do all of the items below. Just pick the items you think your guests will like. You don’t have to do squash and sweet potatoes, or offer three different vegetables. These are just examples.

Turkey: 40 pounds. So four 10 pounders, three 14 pounders, etc.

Dry mix stuffing: 40 ounces dry, so seven boxes. A lot of people go heavy on stuffing and it’s cheap and easy, so having extra won’t hurt. I’ve found the in-house brands like Walmart are just as good as the big name product and cost half as much.

Potatoes for mashing: 240 ounces raw. So 15 pounds of russets, peeled, cooked, mashed, and prepared as you like with milk, butter, salt, pepper, garlic, etc.

Sweet potatoes: 240 raw ounces. So 15 pounds prepared as you prefer.

Canned cranberry sauce: 160 ounces, so ten or twelve 14 oz cans. These could be split between cranberry jelly and whole cranberry sauce. Some people like one and not the other.

Pie: 40 pieces. For big pieces you’ll need seven pies, smaller pieces, 5 pies.

Butternut squash: 280 oz raw whole squash (17 pounds)

Brussels sprouts: 100 oz raw (6-1/4 pounds)

Green beans: 160 oz (canned), so ten or twelve 14 oz cans. When cooking raw whole beans, I figure six beans per person. A pound of raw beans is 35 to 40 beans. For 40 guests you need to cook about six pounds.

Conclusion

You can save money by buying larger cans. In supermarkets, verify that the larger container is actually cheaper. Many times I’ve seen a gallon jar of mayonnaise or other product priced higher than buying the same amount in several smaller jars.

Larger towns have stores that sell wholesale foods to churches and other organizations, and sometimes to the public. Here you can buy Number 10 cans (institutional size) that contain around 115 ounces, and save even more money.

Saran Wrap Isn’t What It Used To Be

In the 1960s, I used to help my mother in the kitchen and learned how to cook. I used Saran Wrap to cover plates and bowls, and I noticed that this material was sort of magical. It stuck to what I wanted it to stick to and wasn’t much inclined to stick to itself. What is this sorcery? You could pull it back to access something in a bowl, then seal it back up again. I was fascinated because it seemed like it was intelligent. I had studied some chemistry but not yet enough to guess the cause for this marvelous behavior.

So what was this wonderful material I was working with? In 1933 a chemist at Dow Chemical was trying to develop a new dry cleaning solvent. He noticed that certain beakers and glassware were hard to clean. They had a residue that was hard to scrub off. Investigation revealed a new substance, a new polymer that was named polyvinylidene chloride or PVDC.

It was found that, among other things, PVDC made a tough and durable clear coating. During World War 2, virtually every U.S. aircraft was coated with PVDC to help protect it from the elements. At the end of the war, hundreds of companies in the U.S. got busy looking for commercial applications for the countless marvelous things they had developed for the war effort. Somebody at Dow realized that PVDC would make an excellent food wrap. And excellent it was, as you will see later. Production methods for forming PVDC into a very-thin film were developed. The CEO of Dow decided to name it after his wife and daughter, Sarah and Ann: Saran.

The product was introduced in 1949 and was an almost overnight success. This is the stuff I was using in the 1960s. Towards the end of the 1960s, Dow’s patents expired and other companies began producing PVDC food wrap, like Glad Wrap. They were all just copies of Saran Wrap.

From the 1990s forward, I didn’t use much plastic food wrap until I began to work in a restaurant in 2012. There, I used plastic food wrap all the time and immediately noticed that it behaved differently from what I remembered. Sure, it worked, but it frequently refused to stick to some things and it was eager to stick to itself. This is not what I remembered. After opening and closing a covered bowl, the plastic wrap would become wrinkly and refused to stick to anything. I covered a mixing bowl full of diced onions with this plastic wrap and placed it in the cooler. Soon, the cooler smelled strongly of onions. What? That’s not supposed to happen. What is this stuff? Maybe some kind of cheap imitation of Saran Wrap?

Time passed, I finally did some digging on the Internet, and immediately found the answer. Through the 1990s, chlorinated polymers like PVDC became an increasing environmental concern. In 2004, all the makers of PVDC plastic wrap switched to ordinary low-density polyethylene (LDPE). Polyethylene is cheap and easy to make into a thin film. But there are problems. Big problems.

First of all, polyethylene is a low-friction, non-stick kind of polymer. This is why milk bottles are made from it. Polyethylene film doesn’t stick to anything, nor itself. Today’s polyethylene plastic food wrap is coated with a moisture-activated adhesive to make it “cling”. At best it clings to certain things but not others, and it eagerly sticks to itself, making it hard to work with.

Secondly, the adhesive quickly wears out so opening and reclosing a bowl covered with modern plastic wrap is something you might be able to do once but not repeatedly, like you can with PVDC film.

Thirdly, polyethylene film is around 3,000 to 4,000 times more permeable than PVDC film. Oxygen is the main culprit that causes food spoilage. For every one molecule of oxygen that a given area of PVDC film lets through, polyethylene film lets through 3,000. The consequences of this are obvious. This also explains the experience I had with onions stinking up the cooler. That wouldn’t have happened with PVDC film. In fact, certain meats are still packed with PVDC film because polyethylene film can’t do the job.

The bottom line for me is that I was pleased to discover that my memories from the 1960s were pretty accurate. However, I was not pleased to discover that the plastic film I use today is inferior in terms of performance and user friendliness, and there’s no way to fix it.

Today’s plastic wrap looks like classic Saran Wrap, but it ain’t. It’s not even close.

Mayhem At Walmart

I took a few photos of the mayhem left by the hoarders. Paper goods, milk and dairy, disinfectants like Lysol, wipes, and hand sanitizers were all stripped bare. Below are some photos.

Toilet paper and paper towels gone

Milk section, stripped

Dairy stripped

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