Understanding Processed Food

By Kathryn Haydon


            “Don’t eat processed food!”

This is a common piece of advice for people who want to eat healthier to prevent diet-induced obesity and heart disease. But food scientists understand this advice as an over-simplification of a complicated issue, and we want to help you understand what processed food really is so that you can make more informed decisions in the grocery store.

Processing is any change made to a raw agricultural product after harvest.

Farms produce food, it’s true, but straight from the farm that food is a raw, sometimes inedible product. Although whole fruits and some vegetables can be eaten as-is, most foods are processed before they reach our grocery stores, restaurants, and home kitchens. Processing can be physical, such as sorting, washing, shelling/dehulling, peeling, milling, and chopping; thermal, such as freezing, cooking, drying, sterilizing/retorting, and pasteurizing; chemical, such as fermentation, salting, sweetening, and adding nutrients or preservative compounds; or transformative, whereby multiple ingredients are combined in prepared foods that don’t closely resemble their individual ingredients. (Packaging is also a form of food processing, but won’t factor into this post as much.) Most foods are subjected to several processes in these different categories before consumption. And as the level of processing increases in a food, the convenience of that food also tends to increase.

Before most food processing was done in factories in the developed world, all of this food processing was done by someonemostly women—in home kitchens. This is really important to remember, because the more you base your diet on minimally processed foods, the more processing you have to do yourself before the food is ready to eat. Today, no one in developed countries needs to mill their own flour, bake their own bread, churn their own butter, culture their own yogurt, boil their own chicken stock, can their own fruits and vegetables, or shell their own fresh peas, unless they want to! Such activities are typically reserved for upscale restaurants and food hobbyists on weekends. As a home cook and food hobbyist myself I spend 1-2 hours each weekday and up to 5 hours each Saturday and Sunday preparing food, but I still rely on basic processed foods like canned tomatoes, beans, and chicken broth, prepared breads and pasta, and milled rice, flour, and starches.

Processing is just a tool, and therefore it can be used for good or for ill, whether in a home kitchen, a restaurant, or a factory. For example:

Processing can degrade nutritional value or create toxins: Most wheat flour and rice are consumed after milling has removed the fibrous, nutrient-filled bran layer. Fruit juice, though still full of vitamins, provides all the sugar of fruit without the fiber that slows down absorption of that sugar into the blood stream. Acrylamide is a possible human carcinogen that is produced when frying potatoes. Nitrites are added to cured meats as preservatives, but are also associated with negative health effects.

Processing can enhance nutritional value and eliminate toxins: Government-mandated fortification of refined flour is credited with greatly reducing neural tube defects in developing infants. Flash-freezing vegetables prevents the loss of nutrients that begins immediately after harvest. Canning tomatoes boosts bio-available lycopene content. Parboiling rice transfers nutrients from the bran and hull into the starchy endosperm so even after milling it retains these vitamins. Treating corn with an alkaline solution makes the essential B3 vitamin niacin bio-available. One of the primary purposes of food processing is preservation by preventing microbial growth, and thermal and chemical processing can also neutralize natural plant toxins (see our video for more info!).

Processing can be used as a vehicle for high loads of sugar, salt, and fat: Some of the most highly processed foods in grocery stores are also nutritionally unbalanced to an extreme degree. Chips, crackers, cookies, candy, sugar-sweetened beverages, boxed prepared foods, and yogurt sweeter than ice cream: these are just a few examples of foods that will give you a lot of Calories without a lot of micronutrients, or fiber to promote healthy digestion. Most of the time when people say you shouldn’t eat processed food, this is what they’re talking about!

Processing can be used to make nutrient-dense foods more convenient and accessible: Canned vegetables, particularly beans and tomatoes, are faster to prepare than their fresh counterparts. Baby carrots, which are really whittled-down version of large carrots, are a great ready-to-eat snack. And by processing fruits and vegetables into more shelf-stable products, we can enjoy year-round variation in our diets.

Why would we ever process foods in ways that lead to nutrient loss or imbalance? The answer to that question comes down to palatability, functionality, and shelf-life. Consumers prefer white rice to brown, and we’ve also developed a strong preference for sweet foods, such that even savory items like jarred tomato sauces and whole-wheat bread contain added sugar to moderate acid and bitter flavors. Processing can also enhance final products; for example, white flour produces softer, more high-rising breads and baked goods, and hydrogenating plant oils prevents unsightly oil separation. Fresh foods spoil quickly, and many processes that strip nutrients also promote better storage, which ultimately reduces food waste. Every process we apply to food has costs and benefits.

Unfortunately, the mentality that processed foods = bad hasn’t given us less processed food as much as it’s given us reformulated processed foods. We eat “multigrain” pasta that still lacks whole-grain nutrition, brightly-colored sugary cereals made with “natural” flavors rather than artificial ones, and fruit snacks made from apple puree concentrate—which looks better on a label than “sugar” even though that’s what it is! These lateral moves in food composition haven’t given us more nutritious options. As long as our diets are primarily composed of high-Calorie, low-nutrient convenience foods, we won’t make meaningful steps to reduce preventable diseases.

From a food scientists’ perspective, the proper response is not to shun all industrially processed foods, abandoning modern life to devote yourself to food preparation. Rather, we need to rely on other criteria—Calories, macronutrient and macronutrient composition, fiber, and servings of fruits of vegetables—to choose the best whole and processed foods for healthy diets.

Eat processed foods, don’t eat the pseudoscience.






Kathryn is a native Texan with a B.S. in Biology from the University of North Texas, and is currently finishing her M.S. in Food Science at the University of Arkansas, where she will be starting a Ph.D. in Plant Science in August! She studies impacts of post-harvest processing on rice quality now, and will be studying the genetic basis of rice quality in the future. She spends way too much time snuggling with her cat, watching Netflix with her husband, and tweeting (@kathrynhaydon!). You wish you could come to her house for dinner tonight, because she’s probably cooking something delicious.

20 thoughts on “Understanding Processed Food

  1. This article basically has no information in it, it’s a rude waste of readers time. Shame on the author.


    1. I’m sorry you feel this way, Sophia. Many readers have enjoyed the post and found its information valuable, but I understand that we can’t be all things to all people. Is there anything specifically you think I failed to address?

      Liked by 2 people

    2. Waste of time? Serioiusly Sophia? I learned more in one reading about legitimate concerns with processed food, than I have in years of reading Facebook posts by people starting out their rant with “As a nutritionist, I…”

      New favorite wordpress. Thanks donteatthepseudoscience!

      Liked by 2 people

    3. I have to respectfully disagree, Sophia. Far from a rude waste of readers time, I found the article to be a sensible, intelligent overview of food processing, its purpose and function. I, like some of the other commenters, are growing weary of the automatic condemnation and catering to distrust that typifies so many self appointed food police. I want truth, and although I do not fully accept major food makers explanations, I am equally, if not more, distrustful of advice of people like the Food Babe. I am not saying all processing choices made by food makers are without question, but this article points out that there are many valid and valuable purposes served by processing steps, and in most cases, processing preserves food nutritional values, avoids food safety issues and reduces waste.

      I am sorry if you want an autopilot condemnation of the food industry that validates and caters to fears and suspicions. I prefer articles that respect our intelligence. I feel far better informed by reading this article.

      Liked by 1 person

    4. The only thing I don’t like about this excellent article is that it’s too short. It would have been interesting to hear about some of the world’s traditional foods that are deadly poison unless processed. I particularly like the level-headed tone and scientific accuracy.


      1. I’ll take that criticism as a compliment! We didn’t want this post to be a TL;DR, but there is so much more I’d love to write about this topic. Maybe we can dedicate a future post to discussing the detoxifying effects of processing. We made a short video introducing that very idea, but I could go into more detail about it here. Thanks for reading!

        Liked by 1 person

  2. Thanks for the information in this article. When someone says they try to avoid processed food, most people know what they mean. To me it means eating foods as close as their natural origins as possible. I realize that when I chop a carrot or use whole wheat pastry flour I’m using a processed food. But I’m getting weary of skeptics (and I consider myself one!) scoffing and snickering knowingly at those who say the don’t eat processed food, when they really do know what type of processed food they’re referring to. Is there a better term we could use? If so, let’s start using it!

    Liked by 1 person

  3. Loved the article, just one tiny quibble: Where you say ” we’ve also developed a strong preference for sweet foods” and that is why bread and tomato sauce are sweetened. Sugar is required to activate the yeast when baking bread. If you don’t use, it, eventually you may get a rise but it will take ages, and during this long process fermentation can occur and that makes the bread have a sour taste that is not always desirable. Sugar also impedes gluten strands being formed and this makes the bread softer. Finally, sugar helps make a nice brown crust. If you look at the proportion of sugar compared to other ingredients in a bread recipe , you will see that the amount is so low it would not really provide much of a change in flavour, but the ease of preparation and the effect on texture is significant. Even a bit too much sugar in tomato sauce is revolting (as i have learned from experience lol). However, just a bit goes a long way to balancing the sauce so you can taste all the goodies in it and not have your taste-buds overwhelmed by the acidity of the tomato.

    Liked by 1 person

    1. You’re totally correct! I was pointing out that those foods often contain added sugar in amounts greater than what is needed for functionality, and those amounts are partially determined by tasting panels with sweet preferences. For example, a loaf of whole wheat sandwich bread may contain 1 tsp. of sugar per slice (and only a miniscule percentage of that comes from the wheat flour)–more than the homemade recipe I sometimes prepare that still keeps the yeast happy and produces a wonderful brown crust. Similarly, a homemade tomato sauce would add 1/4 tsp. of sugar per serving at most, but jarred sauces can contain 3/4-1 tsp. (or more) per serving in addition to the sugars in the tomatoes themselves. So I’d still suggest that, on average, savory convenience foods contain added sugar to appease palates as well as provide useful properties.

      Liked by 2 people

  4. When I say I avoid processed foods, I am talking about the crackers, cookies, etc that are far away from anything natural. If I want cookies, I bake them so I know what’s in them, and they don’t need a shelf life. 90% of baked goods I eat are 100% whole grain. I chop fresh onions, garlic, celery, and herbs into my dishes rather than using powdered flavorings from the spice aisle, because I can get the nutrients that way and it does taste better. I stay away from dairy products from cows treated with hormones. And forget stuff like hot dogs, chips, boxed prepared dinners, and prepared frozen meals and desserts. I’m not vegan and I don’t stick with all this if I’m invited to dinner by others.


    1. You and I probably have a lot in common with how we like to cook and eat, but I think it’s important to recognize that not all people in developed countries living busy lives can or want to prepare all their foods at home from less-processed ingredients. Having access to inexpensive, easy-to-prepare foods allows us to spend more time doing what we want or need to do and also spend a smaller percentage of our income on food. It’s important that home cooks such as myself remember that and not look down on people’s food choices. I’m glad you loosen up when eating with friends–I do too. Food isn’t just about nutrients! It’s about community and culture too.

      I would caution you about some of your statements about food: A homemade cookie is not really more “natural” than a packaged one, artificial hormones add mere nanograms to dairy or meat compared to what the animal naturally produced, and even nutritionally-imbalanced foods can be enjoyed in moderation. Buzz-words like “natural” and “hormones” are misused in food discourse and don’t actually help us understand food and nutrition, but they do promote putting food into good/bad categories that ultimately create harmful stigma. Part of what Don’t Eat the Pseudoscience is about is using evidence to evaluate the way we talk about food to create a healthier understanding.

      Liked by 3 people

  5. We need fewer Food Babes and more Food Nerds (in this case, the moniker is intended as a compliment). Thank you for an intelligent article.

    Liked by 2 people

  6. Great read! I often use the word processed when I’m referring to chips, crackers, junk food etc not realising that it also includes processing from a raw agriculture product like honey or maple syrup.


  7. the vernacular use of the word processed in this context is still important. We know the difference between chemical laced food and whole food, so who carest if ‘processed’ is the word we use to clarify this differnece.


    1. I don’t think the vernacular use of “processed” is as clear-cut as you suppose. For some people it just means high-salt, high-sugar, and/or high-fat convenience foods that should be consumed in moderation only, for others it means vilifying frozen, canned, or pre-cut fruits and vegetables, only deeming fresh, whole produce acceptable for consumption. The vernacular use of the term “processed” also ignores the fact that a lot of processing happens at home. A home-baked loaf of bread or batch of cookies may be very satisfying, but it is just as processed as anything made in a commercial facility and purchased in a store.

      You don’t strengthen your argument for using “processed food” when you equivocate it with “chemical laced food.” Your rhetorical choice of “laced,” a word most often used to mean “contaminated with a (usually harmful) substance,” indicates a preoccupation with additives in some processed foods. These additives are chemical compounds added in very small amounts to the more numerous natural chemicals in the food to enhance functionality, flavor, or shelf-life. Additives deserve their own post on this blog, but for the sake of this comment I will just say that these additives are present in such small dosages that they are inconsequential to the overall safety and nutrient value of foods. But because they are often identified with chemical names rather than common names, food bloggers use them to scare consumers into thinking their food is not safe, while selling an alternative.

      An incorrect understanding of “processed food” has allowed companies to take advantage of people and sell them the illusion of less processing with label claims like “natural” and “no high-fructose corn syrup.” So yes, I still think we need to be clear about what “processed” really means.


  8. Reblogged this on In Your Face Nutrition and commented:
    One of my personal pet peeves is hearing someone say “don’t eat processed foods”.
    Food processing has done wonders for our global and local food systems. If you eat frozen berries or canned tomatoes you eat processed foods!
    The foods we want to eat less of are ‘hyper’ or ‘ultra’ processed foods. These foods have been dramatically altered from their original state by adding sugars, fats, and other additives.
    Baked goods with an extended shelf life (Jos Louis and twinkies), potato chips, frozen meals and fruit drinks can all be considered ultra-processed. These are the foods we can try to eat less of by trying to get into the kitchen, one step at a time to make our own snacks and meals.


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