21.3: Does Processing Affect Nutritive Value?

There’s no question that the preparation of food for consumption or storage has some effect on nutritive value. Food begins to change as soon as we take it from the plant. Some vitamin values fall as it goes from farm to store to home. In the cook’s domain, cooking time, the amount of water used, and the temperature of the water all affect nutritive value.

In general, the commercial processor has tight controls over all these factors and takes pains to minimize the lag at each step—from the field, to the production line, to the final product available to the consumer. Very few home cooks have direct access to a crop. If they do, they may or may not be so quick or scrupulous with the harvesting, cooking, or preserving.

So the nutrient loss with home processing is often greater than that of commercial processing. The consumer can minimize nutrient losses at home by storing fresh foods in the cold (to inhibit the chemistry of vitamin deterioration), cooking in minimal amounts of water if the water is to be discarded (to lessen the loss of water-soluble vitamins), and not over-cooking (to lessen the heat-destruction of some vitamins).

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Nutrient losses during home storage and preparation mostly involve vitamins. Minerals aren’t destroyed by light or heat.

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Today’s questions of processing and nutritive value are much more than a matter of concern for nutrient losses. With the nutrient fortification of so many foods (e.g., vitamin D-fortified milk, iodized salt, vitamin and mineral fortified breakfast cereals), modern food processing has, ironically, done more to prevent vitamin and mineral deficiencies than cause them. Some refined foods may even have more vitamins and minerals than the unrefined. Iron and some B-vitamins, for example, are routinely added to white flour in this country, making white flour a richer source of some of these nutrients than whole-wheat flour.

But does this make white flour more nutritious than whole wheat flour? The answer could be yes, because many children and women don’t get enough iron, and enriched white flour is a little better source of iron than whole wheat flour. But the answer could also be no, because many people don’t get enough fiber in their diet, and whole wheat is a richer source of fiber. Also, other nutrients lost in the refining process (e.g., potassium, zinc) are not replaced in enriched white flour. (Nutritionists encourage whole grains in the diet.)

Complicating the processing/nutritive-value evaluation even further, there are food components that have nutritive value, but that consumers want removed by food processing, to make them more “healthful.” Just think of the array of “diet foods” available at the supermarket.

Loss of Taste Versus Nutrient Loss

Why do many consumers believe that processed foods are nutritionally lacking? One reason is certainly taste, the idea being that taste and nutrition go hand in hand. The truth is that, although a food gone bad suffers in both nutrient quality and taste, one can’t judge nutrition by whether the food is tasteless, moderately tasty, or exquisitely delicious.

Crops are often chosen for their ability to survive processing or for their uniformity of size and color—at a sacrifice of flavor or texture. Also, it’s easier to preserve the nutrients than to preserve taste and texture. Frozen berries may seem like a distant relative of the fresh berries you pull off a wild vine along the mountain stream. The frozen berries may leave you wistful, but their nutrients are well-preserved.

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A popular comment—made only half in jest—is, “It tastes so good, it surely can’t be good for us” or “It tastes so bad, it must be good for us.”

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Part of the doubt about the nutritiousness of processed food can be blamed on unrealistic advertising. Advertisers often go too far when they try to convince us their cookies, soups, or frozen entrees are “just like grandma used to make” (unless, of course, she was a dreadful cook). When the product fails to live up to the billing, we feel swindled. After all, why should we be expected to accept industry’s claims for nutritive concern and care and quality, when its advertising for a dismal, frozen meatball has implied that the poor thing would delight the senses of a Florentine chef?

Processors are constantly striving to improve flavor and texture. The biotech-produced Flavr Savr tomato, mentioned in the last chapter, is but one example. Anyone who thinks that processors don’t leap to seize any advantage in flavor or food value grossly underestimates their business sense.

If we want to fix a hot dinner in five minutes, we can have it, and it will be good and safe for survival, but there’s often a price in pleasure. The use of convenience foods is a personal choice.

It’s perhaps what and how much we choose to eat because of convenience that causes people to associate processed foods with nutritional emptiness. If there’s anything “unhealthful” about the advances in food processing, it’s that it has brought us an extremely handy variety of food—so attractively packaged, so easily stored, and so convenient to eat, that it is easy to overeat. How often would you eat potato chips if you had to make them yourself from a fresh potato?

What’s “Natural” Food?

Consumers often put considerable emphasis on distinctions between “processed” and “natural” foods. The terms are widely used without question. The world “natural” is a powerful stimulus for consumers, who seem to feel that “natural” food is much more healthful, and that “processed” means degraded, at least in terms of healthfulness.

Post’s Grape Nuts are billed as a “Natural Wheat and Barley Cereal.” But its long list of ingredients include malted barley (meaning that starch in the barley has been broken down to the sugar maltose) and eight added vitamins.

Kellogg’s All-Bran is sold as “A Natural Food Fiber Cereal.” It’s so-called, presumably, because its first listed ingredient is wheat bran. Wheat bran does contain substantial fiber, and it’s part of a plant’s natural growth. But how natural is it after machines take the bran part of the wheat kernel, mix it into a secret recipe, shape and bake the dough into tiny crunchy cylinders, and package it all into a double wrapper of bag and box? Other “natural” breakfast cereals include corn syrup or nonfat dried milk, which certainly don’t come directly from cornstalks and cows.

But, clearly, the intent of the consumer is to get food which is as close to its original state as possible. And equally clear is the belief that such food is more healthful. We have seen that this isn’t necessarily true in terms of nutrient content, but it’s generally true that minimally processed foods tend to be more nutritious. A diet centered around these foods is recommended by nutritionists.