Antioxidant Overview

The chemical compounds present in plants are generally called phytochemicals. Thousands and thousands of these compounds are naturally found in the leaves, fruits and seeds of plants. These phytochemicals normally are present in the plants for specific reasons.

They can help plants grow, help plants fight diseases caused by different pathogenic microorganisms, or simply be present for other functions of which we are not yet aware.

Some of these phytochemicals may be poisonous to humans and animals, but many provide health benefits to us through our diets. The many known phytochemicals are categorized under different chemical groups such as phytosterols, terpenoids, polyphenols and lignans, as well as many other categories.

Antioxidants are chemical compounds that prevent oxidation of other compounds. Synthetic and natural antioxidants are widely used in the food industry to prevent oxidation of fats and oils, and thus eliminate rancidity. The term “antioxidant” has also come to refer to phytochemicals that are grouped together based on their ability to provide health benefits to humans and animals. They prevent the oxidation of different compounds in the human body, reducing or eliminating the formation of harmful radicals that are responsible for the initiation of chronic diseases such as cancer, cardiovascular disease, diabetes, Alzheimer’s disease and many others. Antioxidant compounds are found in many fruits, vegetables and grains. They are categorized into groups according to their chemical composition. Some examples of these groups are: phenolic compounds, flavonoides, carotenoids, terpenes and many others.

The different antioxidants in grains have been known for a long time. However, in the past – due to the demand of baked goods made from refined flours – their health benefits did not reach the consumer. Almost all of these compounds are present in the outer parts of the kernel and are removed during milling of the flour as bran and germ. Bran and germ contain high amounts of antioxidants. Specifically, the bran contains many phenolic compounds, flavonoides, ferulic acid and carotenoids, while germ contains high amounts of tocopherols (vitamin E). We are now more health conscious and better understand the relationship between diet and health. Because of consumer demand, attempts are being made to produce food products with whole-grain flours.  Indeed, phytochemicals in grains such as phenolics, flavonoides and carotenoids, which are responsible for many health benefits, are tightly bound in other components of the grains such as fibre, which is mainly found in the outer layers of the seed.

The hunt for new sources of powerful antioxidants that can be used in our foods led to many obscure fruits and berries becoming popular in North America and Europe. The pomegranate – a fruit little known in North America a few years ago – is now popular in the minds of consumers due to its high antioxidant activity. Other fruits, such as coffeeberry and acai, also gained popularity due to their high antioxidant content. Indeed acai – the berry from a palm tree species from the Amazon – is touted as providing many more times the amount of anthocyanins as red wine. Many other fruits and vegetables cultivated much closer to home than these exotic types contain powerful antioxidants. Blueberries contain high amounts of anthocyanins. Asparagus contains the powerful antioxidant rutin, while grapes produce resveratrol, which some claim provides protection against cardiovascular disease and cancer.

There are many methods used for the determination of the antioxidant activity of the different grains, fruits and vegetables. Some are more specific or more effective than others. One of the methods that has been quite popular recently, and is becoming well recognized, is the oxygen radical absorbance capacity (ORAC) value, which measures the total antioxidant activity of the sample, providing an overall value without identifying the source.  

The majority of antioxidants in fruits are found on the skins, which are – in many cases during processing – discarded or diverted into animal feed. Realizing the added value of antioxidants in these by-products, researchers in many parts of the world are investigating fruit peelings, pulp, seeds, skins and many others for their antioxidant capacity and the production of ingredients from these byproducts. Specifically, skins of tomatoes, apples, peaches, pears, grapes, plums and other fruits are found to often contain more antioxidants than the whole fruit. But commercial production processes for stable ingredients from these antioxidant rich by-products must be carefully considered.

Ingredients for the food processing industry usually take the form of a powder. The production of powders from these products requires dehydration, which is normally done with exposure to heat. The exposure to heat reduces and sometimes completely eliminates the antioxidant activity, but new, gentler processing technologies have emerged to counteract this tendency. These technologies are capable of dehydrating fruits, vegetables and their processing by-products to shelf-stable powders, and at the same time, preserving their antioxidant activity. In addition to preserving the antioxidant activity of ingredients, this exercise will be meaningless if the antioxidants cannot reach the consumer. It is therefore important that the processing of food products containing antioxidants is not so severe as to destroy them or reduce their activity.

However, it is also very important that the food processing is adequate to safeguard the consumer from the danger of food pathogens and provide the quality parameters the food product requires.

The addition of antioxidants in baked goods could be achieved by various methods.

Incorporating whole grains or other antioxidant rich parts of grains such as bran and germ or fruits will boost their content in the finished product. Choosing this method of incorporating wholesome ingredients containing antioxidants is advisable because they are in their natural state, but doing so could have its drawbacks. There is a limit to the amounts of antioxidants that you can deliver in the final product. Alternatively, extracted antioxidants from many sources are available from many suppliers. They can be incorporated into foods at higher levels.

Regardless of the method of incorporation or the source, food producers must make sure that the finished product delivers the functional antioxidant to the consumer because many of these compounds can be damaged by the processing methods used in food production.

For more information, or fee-for-service help with food technical and processing issues and needs, contact Dr. John Michaelides at John Michaelides Consulting at 519-743-8956 or j.jmichaelides@gmail.com, or at Bioenterprise by calling 519-821-2960. Bioenterprise is a company made up of experienced professionals who coach and mentor emerging agri-technology companies from planning to start-up to profitability and beyond.