Milking chocolate for its health benefits | Science News for Students

Milking chocolate for its health benefits

Researchers find a way to give milk chocolate the same nutritional punch as dark chocolate.
Nov 28, 2016 — 7:00 am EST
milk chocolate

The process for making milk chocolate removes most of its natural — and healthy — antioxidants. Scientists have now found a way to add antioxidants back in without adding any bitterness.


You may have heard that dark chocolate is healthier than milk chocolate. If you are like many people, though, you prefer the sweeter, less bitter type. That means you’re missing out on dark chocolate’s heart benefits. But you may not have to accept this limitation much longer. Researchers have just figured out how to give milk chocolate the same nutritional punch as the dark stuff. And they did it by adding a surprising ingredient. Even better news: The process doesn't change the treat’s flavor.

No one should eat lots of chocolate thinking that it will make them healthier. Chocolate, after all, usually contains fat and sugar. But dark chocolate does have some chemicals that research has linked to heart health. Known as antioxidants, these chemicals show up in many fruits, vegetables and nuts.

Antioxidants can stop a chemical reaction in the body known as oxidation. Too much oxidation can damage cells. Research has shown that oxidation underlies a host of illnesses, including cancer and heart disease.

All chocolate is made from cocoa beans, which contain antioxidants. To produce chocolate, the beans are broken down into cocoa solids and a type of fat called cocoa butter. Put those two parts back together and you have unsweetened chocolate, which doesn’t taste very good. Adding sugar produces the tastier, though still somewhat bitter, dark chocolate.

Milk chocolate contains cocoa solids and cocoa butter. It, however, has more sugar than dark chocolate. It also has milk or cream. This makes the candy lighter in color and smoother in taste. But gram for gram (or ounce for ounce), milk chocolate contains less cocoa than dark chocolate. That means it also has fewer antioxidants. 

Yet scientists can't just add antioxidants to make milk chocolate healthier — without affecting its taste, anyway. After all, these chemicals tend to taste bitter. "It gives you that mouth-puckering feeling," explains Lisa L. Dean. This food scientist is an author of the new study. Dean works for the U.S. Department of Agriculture at North Carolina State University in Raleigh.

Dean and her team now report having found a way to top up the antioxidants in milk chocolate — without making it bitter. Their secret ingredient? Peanut skin extract. (An extract is a substance, often in concentrated form, that has been removed from its natural source.) She and her colleagues described their new chocolate recipe in the November Journal of Food Science.

Not such a nutty idea

The researchers weren't actually trying to make a healthier milk chocolate.  They were merely looking for a way to use up peanut skins. Most peanuts in the United States go to make peanut butter. Their skins end up buried as wastes in landfills.

Recalls Dean: "We thought, what can we do with this food waste?" She and her team decided to extract antioxidants from the skins. Then, to mask the bitter taste of the antioxidant, they mixed the peanut-skin extracts with an edible powder called maltodextrin. It’s made from starchy foods such as potatoes, rice or wheat. With a slightly sweet taste, maltodextrin is a common ingredient in processed foods such as potato chips and salad dressings.

Next, the team added the mixture to milk chocolate. This gave the chocolate antioxidant the levels typical of dark chocolate. Best of all, there was no change in the candy’s taste.

Just to be sure, the team asked 100 volunteers to sample three pieces of milk chocolate. Only one piece in the three contained the peanut-skin extract and maltodextrin.

Eight in every 10 volunteers tasted no difference between the regular milk chocolate and doctored sweet. The other 20 percent picked up on some extra bitterness. These volunteers are what scientists call supertasters. They are particularly sensitive to bitter tastes. Dean says about 20 percent of people are supertasters. That means that few people should notice whether antioxidants had been added  to milk chocolate.

Some candy makers are experimenting with adding antioxidants to their milk chocolate. But Dean says she hasn't heard of any who have used peanut extracts.

"By using an extract, you can put in tiny amounts so it doesn't affect flavor," she says. Dean cautions that milk chocolate containing peanut extracts would need clear labels so that people with peanut allergies could avoid it.

Suzanne Johanningsmeier studies food science for USDA at North Carolina State, but was not involved in this study. Roughly 100 million pounds of peanut skins are thrown out every year, she notes. The new research, she observes, could “reduce food waste by using peanut skins to create a new, health-boosting food ingredient."

Power Words

(more about Power Words)

agriculture     The growth of plants, animals or fungi for human needs, including food, fuel, chemicals and medicine.

antioxidant     Any of many chemicals that can shut down oxidation — a biologically damaging reaction. They do this by donating an electron to a free radical (a reactive molecular fragment) without becoming unstable. Many plant-based foods are good sources of natural antioxidants, including vitamins C and E.

cancer     Any of more than 100 different diseases, each characterized by the rapid, uncontrolled growth of abnormal cells. The development and growth of cancers, also known as malignancies, can lead to tumors, pain and death.

cell     The smallest structural and functional unit of an organism. Typically too small to see with the naked eye, it consists of watery fluid surrounded by a membrane or wall. Animals are made of anywhere from thousands to trillions of cells, depending on their size. Some organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.

chemical     A substance formed from two or more atoms that unite (become bonded together) in a fixed proportion and structure. For example, water is a chemical made of two hydrogen atoms bonded to one oxygen atom. Its chemical symbol is H2O. Chemical can also be an adjective that describes properties of materials that are the result of various reactions between different compounds.

chemical reaction     A process that involves the rearrangement of the molecules or structure of a substance, as opposed to a change in physical form (as from a solid to a gas).

cocoa     A powder derived from the solids (not the fats) in beans that grow on the Theobroma cacao plant, also known as the cocoa tree. Cocoa is also the name of a hot beverage made from cocoa powder (and sometimes other materials) mixed with water or milk.

colleague     Someone who works with another; a co-worker or team member.

edible     Something that can be eaten safely.

extract     (v.) To separate one chemical (or component of something) from a complex mix. (noun) A substance, often in concentrated form, that has been removed from its natural source. Extracts are often taken from plants (such as spearmint or lavender), flowers and buds (such as roses and cloves), fruit (such as lemons and oranges) or seeds and nuts (such as almonds and pistachios). Such extracts, sometimes used in cooking, often have very strong scents or flavors.

fat     A natural oily or greasy substance occurring in animal bodies, especially when deposited as a layer under the skin or around certain organs. Fat’s primary role is as an energy reserve. Fat is also a vital nutrient, though it can be harmful to one’s health if consumed in excess amounts.

fruit     A seed-containing reproductive organ in a plant.

journal     (in science) A publication in which scientists share their research findings with the public. Some journals publish papers from all fields of science, technology, engineering and math, while others are specific to a single subject. The best journals are peer-reviewed: They send out all submitted articles to outside experts to be read and critiqued. The goal, here, is to prevent the publication of mistakes, fraud or sloppy work.

landfill     A site where trash is dumped and then covered with dirt to reduce smells. If they are not lined with impermeable materials, rains washing through these waste sites can leach out toxic materials and carry them downstream or into groundwater. Because trash in these facilities is covered by dirt, the wastes do not get ready access to sunlight and microbes to aid in their breakdown. As a result, even newspaper sent to landfill may resist breakdown for many decades.

nut     (in biology) The edible seed of a plant, which is usually encased in a hard protective shell. (in construction) A fastener with a threaded hole. They typically are used along with a bolt to securely hold the surfaces of two things together.

oxidation     A process that involves one molecule’s theft of an electron from another. The victim of that reaction is said to have been “oxidized,” and the oxidizing agent (the thief) is “reduced.” The oxidized molecule makes itself whole again by robbing an electron from another molecule. Oxidation reactions with molecules in living cells are so violent that they can cause cell death. Oxidation often involves oxygen atoms — but not always.

peanut     Not a true nut (which grow on trees), these protein-rich seeds are actually legumes. They’re in the pea and bean family of plants and grow in pods underground.

processed foods     Foods purchased from a grocery story that are substantially different from the raw materials that went into them. Examples include most foods that come in cans, bottles, boxes or bags. Examples include breakfast cereals, frozen pizzas, canned tuna, jars of spaghetti sauce and dill pickles.

solid     Firm and stable in shape; not liquid or gaseous.

taste     One of the basic ways the body senses its environment, especially our food, using receptors (taste buds) on the tongue (and some other organs).

waste     Any materials that are left over from biological or other systems that have no value, so they can be disposed of as trash or recycled for some new use.


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Journal:​ ​​L.L. Dean ​et​ ​al.​ ​Minimizing the negative flavor attributes and evaluating consumer acceptance of chocolate fortified with peanut skin extracts.​ ​​Journal of Food Science.​ ​​Vol.​ ​81, ​November 2016, p. S2824-S2830. doi:​ ​10.1111/1750-3841.13533.