Canadian “Super Fruits”:
Are they real?

H.P. Vasantha Rupasinghe

Overview
Canadian fruit crops are worth over $700 million annually post-farm gate to the food industry. Apples, blueberries, grapes, cranberries and strawberries represent the major fruit crops grown in Canada. However, recently market trends are shifting towards newer varieties, imported exotic fruits, and value-added fruit products as consumer demand is growing for healthier antioxidants-rich foods1. Emerging imported fruits within Canadian markets includes hascap, chokecherries, black currents, pomegranate, dragon fruit, star fruit, papaya, goji, passion fruit and mangosteen. Evolving value-added fruit products includes juice blends, energy drinks, meal-replacement beverages, smoothies and shakes, bakery ingredients, specialty teas, and various snacks. Recently, some manufacturers have started to identify specific fruits and their products as “super fruits” as a marketing strategy. However, these products have neither received proper scientific assessment nor endorsement by Health Canada. Nevertheless, it seems that as the science-based health benefits associated with antioxidants become more prevalent, existing and newly introduced fruits rich in antioxidants are expanding market opportunities for Canadian fruit producers and processing industries. The overall aim of this article is to discuss the significance and future potential of Canadian fruit crops and their products.

Physiological benefits of fruit bioactives
Canadian fruits (those grown in cooler climates) tend to have high levels of natural polyphenols which are known for their high antioxidant properties². Typically, fruits contain complex mixtures of these compounds³, which include flavonoids (anthocyanins, flavonols, catechins, flavanones, quercetin glycosides), stilbenes, and chlorogenic acid, as well as triterpenes, such as ursolic and oleanoic acids. Flavonoids, in particular, have attracted a great deal of interest during the last two decades due to growing evidence of their beneficial effects on human health which is beyond their direct role as antioxidants². The interest was stimulated mainly by in vitro, animal model and epidemiological studies indicating an inverse association between the intake of flavonoid-rich fruits and the incidence of chronic diseases such as cardiovascular disease, various cancers and neurodegenerative disorders^2,7. The profile and content of flavonoids varies among different fruits, which is one of the reasons for identifying some fruits as “super fruits”. Fruit flavonoids have shown to be positively associated with vasodilator, anti-atherosclerotic, cholesterol lowering and antithrombotic effects against cardiovascular diseases^9-11. Polyphenols present in berries are thought to be potent anti-cancer agents that act on several sites along the carcinogenic pathway such as in the modulation of carcinogen activation and detoxification, inhibition of oxidative DNA damage, alteration in cell signaling, and inhibition of cell invasiveness and metastasis^12-14. Research shows that resveratrol (found in grapes) can extend the life span¹⁵ and reduce blood glucose¹⁶ of experimental animals. Moreover, fruit flavonoids exhibit various other health benefits including neuroprotective and anti-inflammatory effects^17-19.

In spite of scientific advancements, there are no defined scientific criteria that allows for an objective assessment of nutrients, bioactives and potential health benefits to classify fruits as “super fruits”. Some manufacturers have attempted to display ORAC values (oxygen radical absorbance capacity) as a marketing tool. ORAC measures the ability of food antioxidants to scavenge peroxyl radicals under experimental conditions in a test tube⁴. One could argue that ORAC values represent the antioxidant benefits of free radical scavenging to protect biological tissues from oxidative stress, which is linked to almost all chronic diseases and aging. Although ORAC values may provide some basis to biological affects, the true effects of antioxidant constituents from fruits within the human body are much more complex.

What makes a fruit ‘super’?
The health benefits of fruit polyphenols are largely governed by their bioavailability, which differs greatly depending on which bioactive compound is present, and may not be the ones that are dominant within the fruit^20,21. As a result, marketing of foods based on the content of specific bioactive compounds, ORAC values or an in vitro assay can be misleading to the consumer if the bioactive is poorly absorbed and subject to excessive bio-transformation. It is important to understand that disease prevention is based on complex factors including cellular uptake of bioactives, their metabolism and interactions with cellular signaling molecules and many more^20,21. Thus, to establish conclusive evidence for recognizing “super fruits” for specific disease prevention and health benefits, it is essential not only to determine their bioactive profile and content but also the health effects in the context of disease prevention or reduction of the risk²². Carefully designed in vitro studies however still can be useful for initial testing, which then need to be followed-up by the appropriate pre-clinical animal models for specific disease. Though it is costly, confirmation of health benefits need to be supported by well-conducted clinical studies. Despite growing scientific evidence, under the current regulatory framework Health Canada does not allow any health claim to be made for fruits or their isolated bioactives to treat serious life-threatening diseases (Schedule A disease) such as cancers and Alzheimer’s disease (the revised Canadian Food and Drugs Act – amended 26th October 2012). However, the newly introduced Canadian Food Health Claim Roadmap provides the food industry with marketing and promotion strategies, through quantitative declaration of non-nutrients such as polyphenols and specific food health claims such as maintenance of good health, reducing disease risk, and restoring a body function23.

Advances in fruit-based innovations and future directions
The consumer interest in “super fruit” products has recently increased as the food industries are continually developing new innovative products. Canadian horticulturalists are required to continuously select, breed and assess new fruit crops and verities to meet the rapidly changing consumer preference due to changing demography and health consciousness in food selection. For example, Haskap is a recently introduced new fruit crop with higher ORAC values and potential to use for value-added product development²⁴. However, one of the challenges is to understand the adaptability of new fruit crops to Canadian climate and establishing required horticultural practices. Ambrosia, Honeycrisp, Gala, SweeTango, Creston, Sonya, Salish are examples of new apple cultivars that have recently become popular in Canada. Breeding fruit crops for enhanced quality attributes as well as health promoting bioactive profiles should be a future direction. Opportunities also exist to promote unique Canadian fruit crops such as blueberry, Saskatoon berry, hascap, cloudberry, partridgeberry, cowberry, sea buckthorn, aronia berry, mulberry, black raspberry, black currant and elderberry for functional food development. Commercialization of value-added products of Canadian fruit crops could also elude issues related to pesticide residues and allergens associated with imported exotic fruits. Marketing such healthier food products with established clinical evidence will also help in mitigating rising Canadian health care costs due to obesity and metabolic syndrome associated chronic disorders. Innovative and cost-effective technologies need to be further developed for promoting minimally-processed fruits, fruit-based snacks and healthier ingredients.

Processing challenges for the fruit industry
Processing of fruits subject natural bioactives to degradation and/or alteration²⁵. Loss of bioactives of processed fruit products such as juice even when refrigerated or frozen is more rapid than in fresh produce26. Thermal processing steps such as pasteurization of fruit juices, baking or cooking, and heat-based drying cause rapid degradation of bioactives such as anthocyanins^27-29. Therefore, applications of ‘mild’ processing technologies such as vacuum-dehydration, high hydrostatic pressure, membrane filtration and UV exposure have better applications in fruit processing. For example, when compared to the deep-fried apple chips, apple snacks produced through dehydration retained significantly higher antioxidants^30,31. Food matrix and formulations such as mixing fruits with proteins in shakes and dairy-based protein drinks could reduce the bioavailability of fruit polyphenols due to their interactions with proteins^32,33. Strategies to preserve the bioactives during processing and improvement of their bioavailability need to be developed. Fruits and their processing by-products also provide candidate molecules for developing food additives such as antioxidants, colorings, fiber, pectin, organic acids, edible coatings and preservatives/anti-microbial agents³⁴. Established standardized methods of testing for fruit bioactives and assessment of their safety levels when consumed as isolated ingredients or nutraceuticals are required. Understanding of the interaction of some fruit bioactives with prescribed drugs such as statins and chemotherapy drugs need to be better understood. Success of fruit-based natural health products (NHP) in the format of medicine seems to be hindered by the stringent regulatory requirements by Health Canada as well as consumer desire to go for more natural forms of food rather than a pill. To address above challenges and advance fruit processing practices, our food industry, and government and university researchers must work collaboratively in their research efforts.

Conclusion
In conclusion, key value propositions in successful “super fruit” product marketing include selection of a unique fruit, scientific evidence supporting a potential health benefit, protection of intellectual property and innovative branding to attract consumers. It can be speculated that fruit flavonoids could become another mainstream “omega-3” within the functional foods industry. Further understanding of the physiological role of the bioactives of Canadian fruits will expand our food choices and influence our health and overall well-being.

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Canada Research Chair in Fruit Bioactives & Bioproducts, Faculty of Agriculture,
Dalhousie University, Truro, NS, Canada
(*Corresponding author: E-mail: vrupasinghe@dal.ca))