processed foods | Chemistry on Your Table

Nearly seventy years ago, Swanson and Sons over-estimated the amount of turkey they would need for the upcoming Thanksgiving holidays, resulting in an excess amounting to 260 tons of frozen birds (1) sitting in refrigerated railroad cars and a quandary about what to do with it. According to the apocryphal story, when a Swanson company executive on a Pan Am flight was served dinner on a metal tray, he had an epiphany about how to distribute their turkey over-supply. Left-over frozen turkey was combined with peas, a dab of mashed potatoes and gravy, served on partitioned disposable aluminum trays, and marketed to American consumers. “Just heat and serve!”

Thus was born the classic TV dinner of the 1950s (2). Sales reached ten million in the first year alone. TV dinners may not have been the healthiest addition to the American dinner table, but they did help reduce meal preparation time for women who were increasingly seeking jobs outside their home.

In our busy lives, many of us continue to look for convenience in food preparation, turning to pre-prepared, ready-made, packaged or processed foods. Of course, the array of choices in frozen foods has vastly expanded since the early days of bland TV dinners. Indeed some options are relatively healthy, and quite a few are vegetarian, even vegan, such as the Healthy Choice Vegan Curry Bowls, and many do offer substantial protein and fiber.

Certainly, nutritionists widely advise to cut back on processed foods in our diets. Such foods (along with fast foods) have most likely played a significant role in the rise in obesity, cardiovascular disease and diabetes over the last few decades. Indeed, dietary factors appear to make the largest contribution to cardiovascular disease mortality (3). Research indicates that over-consumption of ultra-processed foods in childhood may be linked to weight gain in adulthood. And yet, for most of us, avoiding processed foods is challenging – or simply impossible.

The term processed foods includes a huge range of foods – and not all are unhealthy. Processed foods include anything that has been canned, cooked, frozen, dehydrated, pasteurized, fermented, dried, milled, fortified with vitamins, or combined with preservatives, colors or added flavor enhancers. Certainly canning, bottling and freezing many foods is essential to extending the shelf life of food and allows a wider range of foods to be transported without spoilage or bacterial growth. Pasteurization of milk and cheese has vastly reduced incidences of food poisoning. Breads and breakfast cereals may be fortified with vitamins and added fiber, while milk may have added vitamin D and calcium. In addition, minimally processed foods, such as canned beans, bagged spinach or packaged tofu have been packaged for convenience, without substantial alterations in nutritional content.

Indeed processing has been critical to making food safer and more widely available to an expanding population around the globe. The fact is that most of us do not live near agricultural areas – or have ready access to farmer’s markets.

However, many of the manufacturing procedures of the food industry do substantially alter the nutritional and vitamin content of the food. In addition, processing frequently involves the addition of ingredients such as preservatives, laboratory-created flavors, artificial colors, and emulsifiers, as well as unhealthy quantities of sugar, high fructose corn syrup, salt as well as fats, particularly trans fats. They are typically low in fiber, and provide an abundance of highly refined carbohydrates. Some researchers have further classified foods as “ultra-processed” if they have incorporate flavor-enhancing additives, dyes or stabilizers, in addition to added sugar, salt or oils.

Consumption of ultra-processed foods, such as hot dogs, pizza, chips, candy, soft drinks, energy drinks, starchy breakfast cereals, sweetened yogurt, canned soups, and frozen dinners (think chicken nuggets), has increased worldwide, and now make up 25 to 60% of food worldwide. Most of these foods are highly deficient in dietary fiber and vitamins. As much as 90% of the sugar in the diet of Americans comes from processed or ultra-processed foods. These processed foods are associated with a higher glycemic response. Trans fats can contribute to high cholesterol levels and inflammation. Such foods may also contribute to digestive problems, such as irritable bowel syndrome. There are some indications that even prenatal exposure to processed food may “impact a child’s subsequent risk of developing obesity, diabetes, and hypercholesterolemia.” Clinical trials suggest that people who regularly consume a diet rich in ultra-processed foods tend to eat an average of 500 extra calories a day – and gain more weight.

In addition, industrially processed vegetable oils – such as canola oil, soybean oil or corn oil – are typically high in omega-6 fatty acids, which are linked to increased incidence of cancer. Instead, you want to select oils high in the healthier omega-3 acids. Similarly, margarine is a processed food engineered through hydrogenation to mimic butter. This processing increases the trans fat content. Be careful that such products can be labeled as free of trans fats, as long as a single serving contains less than 0.5 grams of trans fats.

And the food selections specifically marketed to children are often particularly unhealthy. For a mid-day meal, selections such as Smucker’s “Uncrustables” offers a frozen, pre-made, individually packaged peanut butter and grape jelly sandwich, which is richer in sugar than fiber. Their advertising urges: “Snack anywhere, anytime with a grab-and-go Uncrustables sandwich.” When teaching, I often saw students pull out a package of “Lunchables” which is an easy convenience food for a busy parent to toss in the school lunchbox. Yet, it consists of nothing but salty crackers, processed meat and processed cheese.

However, rather than a fresh apple, orange or banana in the lunch box, there may also be a side of “Fruit Snacks”, which basically consist of fruit puree, combined with corn syrup, corn starch, gelatin, artificial colors and flavors, along with carnauba wax. Of course, an occasional snack is one thing, but consumption of such foods on a regular basis may train the taste buds of children to find healthier, more fiber-rich options less appealing.

For dinner, frozen fish sticks and breaded chicken nuggets are marketed as more appetizing to the taste buds of a picky child. Consider the frozen dinner, All Star Chicken Nuggets from Kid Cuisine, which consists of chicken nuggets, macaroni & cheese, combined with corn and a fudge brownie, packaged in kid-friendly colors, displaying a cartoon character. It contains 16 grams of fat (including 4 grams of saturated fat), 25% of the daily recommended allotment of sodium, and 17 grams of sugar. Another selection from Kid Cuisine is advertised as “All American Chicken Nuggets,” also combined with mac & cheese. Notice the consistent absence of any green vegetables. And – corn does not count as a vegetable (4). Unfortunately, these selections are all too similar to the offerings in many American elementary school lunches. It seems probable that a child raised on these salty, sugary, processed foods has a greater likelihood of selecting such (fast) foods as an adult.

For a more detailed analysis of the impact of processed foods on our diet, read Best Before: the Evolution and Future of Processed Food, by Nicola Temple, which also looks toward the future of lab-grown meat and 3D printed food.

It’s a matter of making common sense choices and checking the ingredient list. In particular check the grams of added sugar, as well as high fructose corn syrup. Sugar may also be listed as honey, agave, dextrose, fructose, malt syrup, coconut sugar, or molasses. In addition, look for refined carbohydrates and trans fats. Ultra-processed foods are generally low in fiber and often have unhealthy fats.

Most selections are common sense:

-Yogurts: try to choose one with little added sugar. Be careful when selecting low-fat yogurt, as the fat has often been replaced with added sugar.

-Breakfast cereals: choose one with whole grains and little added sugar. Do we really need artificial colors, such as the vividly dyed Fruit Loops?

-Bread: choose one with whole grain as the first ingredient and little added sugar.

-Crackers: choose ones made from whole grain.

-Peanut butter: choose one that doesn’t have added oils or added sugar.

-Orange juice: choose one with little added sugar. Why choose pulp-free when the pulp adds fiber to your diet?

-Pizza: one slice can give you your daily suggested allotment of salt. They are typically made with refined flour and processed cheese and meats, with few vegetables.

-Canned soups: check the salt content.

In general, some processed foods to limit or eliminate altogether include microwavable popcorn, fruit snacks, instant ramen noodles, granola bars, flavored nuts, and processed meats (5).

As a consumer, you have an over-abundance of choices, however many of the processed options have been specifically engineered to appeal to our taste buds and our natural desire for foods rich in sugar, salt and fat. All of which our cavemen ancestors specifically craved due to their rarity. Some of these junk foods appear to hijack the pleasure centers of our brain (6).

Of course, it takes time and effort to do due diligence on the nutritional content. But it is certainly worth the effort, as the food industry is doing their utmost to sway your choices.

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