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Tag: food chemistry (Page 1 of 2)

Canned Food is Fine


When I was a kid in the 1950s and 60s, my mother had the opinion that canned food was of low-quality and best avoided. I was young and took her word for it. I maintained this opinion myself into adulthood and sometimes shared it with others. But occasionally I wondered because my own observations and experience didn’t agree. In the late 1990s I became sufficiently curious and learned about it. But first some history.

A Real Short History of Modern Canning

The Dutch Navy were the first to seal foods like salmon in metal cans in 1772. For some reason, this process remained unknown outside of the Netherlands.

The rest of the story begins with French military logistics. In 1795, Napoleon offered a large reward to anyone who could develop a way to preserve foods so that armies could have better provisions when deployed, especially in summer temperatures. As you may know, logistics is what wins wars and availability of food was a major limiting factor in what armies could do.

Fifteen years later, Nicolas Appert won Napoleon’s prize after observing that food cooked inside a sealed jar did not spoil. The reason for this was unknown for another 50 years until Pasteur identified the role of microbes in the spoilage of food. The army worked on developing this process but advancement was slow and the wars were over before useful quantities could be produced.

Development of the canning process continued in Europe and the U.S.A. A process was developed for canning foods in hand-made wrought-iron cans, which worked. But the process was labor intensive and expensive. In 1824, Parry took canned beef along on his voyage to the Arctic. In 1829, James Ross took canned food to the Arctic as did John Franklin in 1845. Some of these provisions were found in 1857. One can was opened in 1939 and found to be edible and nutritious but was not tested for lead contamination from the lead solder used to make those cans.

By the mid-1800s, the wealthy began to see canned foods as a status symbol and novelty. By the 1860s, rising urban populations increased demand for canned food. Many inventions and machines were developed to fabricate cans rapidly. Improved processing methods reduced cooking time from six hours to 30 minutes.

Skipping ahead, a big step was the invention of the double-seam can in 1888. These provided a reliable perfect seal and were called Sanitary Cans. This is the type of can we use today. By World War 1, mass production of canned goods was perfected and large quantities of food, coffee, cigarettes, medications, and ammunition were packaged for the soldiers in cans by the British, French, and the U.S.A. At the end of the war, the companies equipped to make such foods like Nestle and Underwood turned to selling to the general public. Canned foods proliferated. It was now possible for European made foods to be sold in the U.S. and vice versa. Canned tomatoes and canned peaches were available year-round, regardless of the season. It was a whole new world.

Expiration Dates and Safety

I’m old so while I now expect expiration dates on foods, it still seems like a new thing for me. I remember when milk started to bear a date, then eggs, then meat. Before that you could write your own date with a grease pencil if you wanted to. And these were manufacturing or packaging dates, not expiration, best by, or use by dates. Food manufacturers soon realized that by putting “use by” dates on everything they could force supermarkets and consumers to donate or discard food that was past the date and sell a lot more product. Very quickly, manufacturers were all-in on putting dates. Customers began to expect dates.

Today, everything has a date. Even bottled water has a date and many consumers think dates are required by law. They are not. The only things in the U.S.A. required to have a date are pharmaceuticals and baby formula.

When use-by dates began to appear on cans, I just laughed. Cans are hermetically sealed and then heated to sterilization temperature or higher, as high as 130C. Most items are cooked in the sealed can itself. There’s no chance for microbial contamination unless the can leaks.

Modern double seam cans like we’ve used for the past 100 years almost never leak. When they do it’s usually visible. If a can isn’t damaged or bulging and passes the appearance and smell tests, it’s safe to eat.

In the 1970s, a trove of cans of freeze-dried food from 1865 was discovered and tested1. There was no trace of microbial contamination and the food was safe to eat. In the 2000s a trove of cans of various foods from the Depression Era (1930s) was discovered which were sent to a food lab for analysis. All of it was safe to eat. The worst case of degradation was the canned corn, which had lost 30 percent of its nutrient value, but was safe to eat.

Do canned foods last 20 years? USDA says “Most shelf-stable foods are safe indefinitely.”

Back to My Mother

In short, my mom’s opinion about canned food was false. But why did she have this opinion? Thinking back on the stories she told me as I was growing up provided the answer. My mom grew up in a big city in Northern Germany in the 1910s and 20s. By the 1920s, a lot of the food on the table was canned because that’s all that was available. Her mother was an early health-food proponent and went to great lengths to seek out fresh fruits and vegetables, gather wild berries and mushrooms. This made an impression on my mother.

When my mom came to the United States in the 1930s, she was astonished at the abundant fresh foods available in markets everywhere, even in big cities. And like most immigrants, she had the idea that everything was better in the U.S.A., which led to her deprecation of canned foods as inferior.

Conclusion

The truth is it’s not a matter of inferior or superior, it’s a matter of cooked versus fresh. If you want raw or lightly steamed broccoli, that’s not going to happen with a can. On the other hand, the can of broccoli will be there waiting for you years into the future without power-consuming refrigeration or freezers. Canned foods tend to be cheaper not because they’re lower quality but because it’s usually prepared near the farm, doesn’t need refrigerated transport, and doesn’t have to be rushed to the market before it spoils. There’s also less waste that has to be refrigerated and rushed to the market. How much of a broccoli head’s mass amd volume do you actually use? A third? The rest goes in the trash but you paid for all of it to come to you fresh.

If you consider the can itself, it’s made of steel, which is cheap, abundant, and non-polluting in a landfill. Unlike plastics, steel is easily recycled but hardly anyone does because steel is so cheap. If you look at the big picture, canned foods make a lot of sense.

Waterproof Lipstick is Forever


Ever more frequently one sees “forever chemicals” mentioned in the news. They’ve become so pervasive they’re found in most water supplies, in the rainfall over Antarctica, and in the bloodstream of every person.

The forever chemicals being talked about are members of a large family of manmade chemicals called PFAS, PFOS, and PFOAS. The archtype of this family is perfluorooctanoic acid. These have been manufactured since the 1940s and do not occur in nature. More members of this family are developed each year.

Perfluoro- and polyfluoro- chemicals have become so widespread because they are so useful. Most of them repel both water and oils. They’re used to make Teflon and other non-stick coatings, stain resistant carpet, water-repellent clothes, fire-fighting foam, ski wax, waterproof cosmetics, and many other products.

These molecules are very stable so they don’t break down in the environment. As a result, they’ve found their way into almost everything — air, water, and soil all over the planet, and inside our bodies.

They are not harmless. In recent years, studies have shown possible causal connections with testicular and kidney cancer, fetal problems like low birth weight, early puberty, immune system problems, liver damage, thyroid disease, blood pressure problems during pregnancy, and colitis.

Study results thus far have been inconclusive but it’s a major concern because these chemicals are everywhere and we can’t effectively get rid of them. They become more abundant each year.

Waterproof Lipstick

Published in The Journal of Environmental Science & Technology on June 15, 2021 is a peer-reviewed study conducted by researchers at Notre Dame University. The study shows that roughly half of the 231 cosmetics tested contained PFAS. Most of these products did not show PFAS on their list of ingredients. About 60 percent of eyeliners, foundations, and liquid lipsticks, and 80 percent of waterproof mascaras contained PFAS. How much are you ingesting? There’s no solid data on this question but the answer is clearly not zero.

Another problem with waterproof lipstick is that it works really well. Too well. Lipstick prints on water and wine glasses are durable. Unlike conventional lipstick, waterproof lipstick is unaffected by the high pressure, heat, and chemicals used in commercial dishwashers. Nobody wants to receive a glass with somebody else’s lipstick print on it. This means that each glass must be inspected and lipstick scrubbed off by hand. A mini-industry has sprung up around this problem that offers special tools, rim scrubbers, and harsh chemicals to help restaurants and bars deal with the problem. This results in more labor and higher costs which will be passed on to the customer.

Please keep the above in mind when making a purchasing decision. You must decide for yourself if it’s worth it.

ADDENDUM:

On March 2, 2023 AP News reported that the EPA is going to start addressing the problem of PFAS in drinking water. However, the article makes no mention of PFAS in cosmetics.

I assume that PFAS in cosmetics has to be addressed by the FDA. Until this is dealt with, buildup of PFAS in the environment will continue.

https://apnews.com/article/pfas-epa-water-regulations-d2d5052c36a5a95f4e56866f028c9c4f

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.

Three common aldehydes

One thing aldehydes have in common is strong and distinctive odors. Another characteristic of aldehydes 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. Acetaldehyde has a strong suffocating odor but at low-concentrations smells pleasant and fruity. Humans can detect acetaldehyde at 0.05 ppm. Diacetyl at a concentration of about 2 ppm with acetaldehyde at about 0.5 ppm are what give cottage cheese its flavor.

Acetaldehyde4 is formed from the oxidation of ethanol. It forms in the bloodstream after drinking alcohol and is partly responsible for hangovers.

⊂•⊃

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

Cuminaldehyde

Cumin, also known as cumino, comino, comyn, cymen, and many other names has been used as a spice / flavoring for at least 8,000 years. It’s common in Indian and Middle Eastern cooking. It was brought to the Americas by the Spaniards where it became an important ingredient in Latin American cooking. The the dominant flavor of chili and “taco meat” is usually cumin. The flavor of cumin comes partly from cymene and several terpenoids, but primarily from, you guessed it, cuminaldehyde.11.

⊂•⊃

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.12

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)13 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.

Furfural14 is classed as acutely toxic, an irritant, and health hazard.15

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. Retinaldehyde16 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.17

Glycolaldehyde

This aldehyde is believed to play an important role in the formation of the chemical building blocks of life.18

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 aldehyde19 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,20 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 citral21 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.22

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. Citronella23 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.24

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.

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.

Plastic Wrap

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 molecule of oxygen that a given area of PVDC film lets through, polyethylene film lets through 3,000. The consequences of this are obvious. It 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 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.

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