Blueberries: Home-Grown Superfruit

By Lynn A. Kuntz, Editor in Chief

After scouring the far corners of the Earth for exotic superfruits, it seems all this time weve had one of the best right in our own backyardthe blueberry.

Blueberries are native to North America. Native Americans were using them long before Europeans arrived, not only as food, but as medicine. For example, they used blueberry-leaf tea as a blood tonic, and blueberry juice as a cough medicine. They ate fresh berries, and added blueberries to stews, soups and meats.

The interest in blueberries keeps on rolling to this day; theyre found in everything from pastries to yogurt to premium pet food. According to Mintel, Chicago, more than 1,200 new products containing blueberries were introduced in 2010.

Blueberries have always been popular because of their natural deliciousness, but their popularity soared with the advent of antioxidant-awareness," says Tom Payne, industry specialist, U. S. Highbush Blueberry Council, Folsom, CA. Blueberries are especially successful because they are both an easy snack, eaten fresh, and an easy-to-formulate ingredient for product development in all categories, from dairy and baked goods to beverages, cereals and snacks."

Beating around the blueberry bush

Blueberries are members of the genus Vaccinium, the same family of plants as cranberries. Among the many types, three predominate: highbush (cultivated" northern and southern varieties), lowbush (wild") and rabbiteye (native to the South). Cultivated, or highbush, berries make up approximately 2/3 of the blueberries grown in North America. Their large berries are more than 1/2 inch (12 mm) in diameter, but this varies from smaller (1.0 to 1.5 gram) fruits to large (greater than 2.5 grams), depending on growing conditions and cultivar.

Lowbush blueberries are smaller than highbush varieties (3/8 inch, or 10 mm), so wild blueberries deliver more than twice the number of berries per pound than the larger cultivated blueberries, about 1,300 to 1,500 berries per pound, says Mike Collins, vice president, Food & Wellness Group, Portland, ME, and spokesperson for the Wild Blueberry Association of North America, Old Town, ME.

While some have similar characteristics to highbush varieties, in general, rabbiteye blueberries tend to have darker fruit, more noticeable seeds, thicker skins and have a somewhat gritty texture (similar to pears). One study found rabbiteye fruit to have a higher pulp pH, percent soluble solids, sugar:acid ratio and firmness compared to highbush berries.

Wild blueberries also have a sweet and tangy" flavor compared to the typically more mellow cultivated berries, according to Collins. The technical explanation lies in the different composition. The sugars in lowbush blueberries include glucose and fructose, while highbush blueberries contain fructose, glucose and low levels of sucrose, and the profile of major acids also differs between lowbush blueberries and highbush and rabbiteye blueberries. Lowbush blueberries aroma is produced predominately by esters and alcohols. Highbush volatiles are aromatic hydrocarbons, esters, terpenes and long-chain alcohols. In all types, flavor and composition is affected by cultivar, fruit maturity and storage conditions.

Superfruit antioxidants

Blueberries claim to superfruit status is owed in large measure to their antioxidant content. Research shows that dietary antioxidants may have a role in reducing oxidative stress, and therefore might slow aging and reduce the risk of many chronic and degenerative diseases, such as cancer, heart disease and Alzheimer's. Oxygen Radical Absorbance Capacity (ORAC) of a food measures its total antioxidant activity.

Depending on the research used, the original fruit using the superfruit title, pomegranate, has an ORAC of about 4,500. (Açaí seems to have an ORAC higher than 10,000, but its not a fruit eaten out of hand.) According to the "USDA Database for Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods (Release 2)," that compares to cultivated blueberries' ORAC of 4,669 (total phenolics 311) and wild blueberries' ORAC of 9,621 (total phenolics 429). For additional antioxidant content, Collins also cites the "USDA Database for the Flavonoid Content of Selected Foods (Release 2.1)," saying, this measurement indicates wild blueberries have nearly two times the anthocyanidin content of cultivated blueberries." Anthocyanin compounds also give the fruit its characteristic blue color. The flavonoids quercetin, ellagic acid and chlorogenic acid add to the antioxidant power.

Healthberries

In 100 grams of blueberries youll find 57 calories, 2.4 grams of fiber and 9.7 grams vitamin C. They also contain minerals such as calcium, selenium and zinc, resveratrol, and the aforementioned antioxidants. While no one has been able to exactly pinpoint what an ORAC score means in terms of specific benefits, research is teasing out the health benefits of blueberry consumption. Studies have been performed on blueberries effects on cancers, inflammation, heart health, digestive health and more.

Payne highlights the potential for blueberries to boost brain health: In one study, Jim Joseph, director of the neuroscience laboratory in the USDA Human Nutrition Research Center (HNRC), fed an amount of blueberries equivalent to a human eating 1 cup of blueberries a day to mice, and then ran them through a series of motor skills tests. He found that the blueberry-fed mice performed better than their control group counterparts in motor behavioral learning and memory, and he noticed an increase in exploratory behavior. When he examined their brains, he found a marked decrease in oxidative stress in two regions of the brain and better retention of signal-transmitting neurons compared with the control mice."

Payne believes these findings could become increasingly important as the U.S. population ages. It is projected that by 2050, more than 30% of Americans will be over 65 and will have the decreased cognitive and motor function that accompanies advanced age," he says. Joseph is currently testing the effects of blueberries on humans. Preliminary results show that people who ate a cup of blueberries a day have performed 5% to 6% better on motor skills tests than the control group."

Research on the antimicrobial properties of blueberries is being conducted by Amy Howell, Ph.D.,  associate research scientist, Marucci Center for Blueberry and Cranberry Research and Extension, Rutgers University, Chatsworth, NJ.  Blueberries have a broad array of nutraceutical compounds that have demonstrated antimicrobial benefits," she says. The flavonoids, including the anthocyanins, flavonol glycosides and proanthocyanidins all have been investigated for their antimicrobial activities. The proanthocyanidins are defense compounds that are produced by the plant under times of stress, including microbial infection. They are responsible for the astringency of blueberriesand cranberriesand most unripe fruit.  Proanthocyanidins are known to provide antibacterial, antiviral and antifungal activities to humans. 

Research indicates that blueberry proanthocyanidins can aid in gastrointestinal health by inhibiting certain foodborne pathogens which cause diarrhea and other GI issues," Howell  continues. They do not appear to harm probiotic organisms, which are important for establishing a health gut microflora. Blueberry proanthocyanidins also prevent E. coli bacteria that cause urinary tract infections from adhering to bladder cells." 

How blue can you get?

Of course, the many types of fresh berries provide a long season of availability, but blueberries come in a number of different formats that can facilitate formulation and production.

Frozen ingredients allow year-round use. Bulk frozen IQF (individually quick frozen) blueberries work best for applications where fruit identity matters. A more economical frozen whole-blueberry choice is straight pack (or sugar-added) flash frozen. These can be used as a base ingredient for toppings, syrups, fillings and soups that need a chunky texture.

Purées and juice are other useful ingredients when piece identity isnt necessary. Formulas for sauces, flavorings and fillings can incorporate pasteurized or cold-filled single strength purées (8.0 to 13.0Brix, 2.8 to 3.5 pH).

Frozen purée concentrate (Brix ranges: from 20 to 40; pH: 2.8 to 3.4) made of fresh crushed blueberries that are heat- or  enzyme-treated, vacuum-concentrated and pasteurized, are another choice for juices and sauces. Single-strength juice (Brix: 8 to 12; pH: 2.8 to 3.4) and juice concentrate (Brix: 45 to 65; pH: 2.1 to 2.7) can be used for fruit juices and to flavor sauce.

Blueberry essence (volatile flavor components distilled off from juice) provides a natural intensive blueberry flavor that can boost blueberry flavor or be used in brewing flavor.

There are also multiple shelf-stable ingredients. Fresh or frozen blueberries canned with light or heavy syrup or with water is a popular choice for fruit filling. For low-moisture applications, like cereals and cake mixes, air-dried (dehydrated fresh or frozen blueberries with 11% to18% moisture; Aw: 0.5 to 0.6) can be made to specific requirementssuch as oil coated, diced etc. Freeze-dried are available in unsweetened (0% to 2% moisture level) and sweetened (9% to 14% moisture). Syrup infusion  stabilizes color and flavor of blueberries for a softer ingredient with an Aw of 0.50 to 0.87 and a moisture up to 40%.

Drum-dried berries ground into powder or flakes (moisture content: 3% to 5%; and various screen sizes and granule consistency) can supply natural color and nutrition. In addition, real fruit bits and chips with fruit contents of 30% to 40% can be formulated from a blend of purée and other ingredients to provide low-cost blueberry piece identity to cookies and other baking and snack applications.

Yum berries

This variety of formats gives product designers innumerable opportunities to develop blueberry products. Beverages are one growing category for blueberries. Payne suggests unique blueberry beverage ideas, including a drinkable ice cream, culinary" cocktails, punch, breakfast beverages, a drinkable crème brûlée shake,  drinkable gelato, or a blueberry cobbler shake. 

The drinkable dessert category is very big now, with product developers whipping drinkability into classics like blueberry cheesecake, blueberry pies and even blueberry muffins," Payne continues.

Desserts are an obvious category, with nostalgic blueberry pies and cobblers keeping company with neo nostalgia" constructs like blueberry millionaire pie, a froth of whipped topping plus sweetened condensed milk and blueberries. Also finding a place in the current bluetopia are frozen cake pops, frozen cream cakes and blueberry ice cream cake," says Payne.

One new category takes advantage of blueberries abundant antioxidantscosmeceuticals. Payne says blueberries are already an ingredient in a realm of products that make the claim for antioxidants. New niche opportunities exist for pairing shelf-stable beauty food concepts with cosmetic brands in department stores where food is not traditionally sold."

Blueberries are also being highlighted in premium pet foods, another application that takes advantage of their antioxidant power. And they can move beyond the kibble mix. The trend toward the humanization of the pet industry is a good fit for blueberry pet-bar formulations in which the blueberry identity reinforces goodness and safety," suggests Payne. 

Blueberries can stand alone, but their flavor also plays well with others. Blueberry works well in  combination with spices, as well as  botanical, floral, citrus and herbal flavors because blueberries complement, enhance and balance these flavors. Blueberrys sweetness blends well with the smoky qualities of sauces and salsas, and the berries fruitiness enhances chocolate-based desserts, candies and confections of all kinds.

As Payne says, With the good news about antioxidants and health benefits in the media, positive consumer attitudes, good availability and a range of formats, blueberries are well positioned to meet development needs.  Blueberries clearly provide many benefits."