A unique functional food ingredient

Have you ever heard of sea buckthorn? Perhaps you have. You may even have a sea buckthorn shrub in your backyard but unsure of what it is. Unbeknownst to you, a goldmine in the form of sea buckthorn berries may be sitting on your land waiting for the right time to come to fruition. Sea buckthorn may not be native to Canada, but it has adapted remarkably well under our climate. Its berries are packed with antioxidant compounds carrying an outstanding therapeutic potential. But how much and what do we really know about the Canadian sea buckthorn? What is the best way to value sea buckthorn berries and help advance our functional food and nutraceutical industries?

The basics of sea buckthorn cultivation

Native to northwestern Europe and temperate zones of Asia, the sea buckthorn plant is a deciduous shrub that grows to a moderate height, ranging from 6 to 13 ft (2 to 4 m). Male and female plants are available, but only the female type can produce fruit. Thus, sea buckthorn orchards should have between seven and 12 per cent of female trees as pollinators. Moreover, shrubs should be spaced 3 ft apart from each other and 13 ft between rows. This nitrogen-fixing plant is relatively tolerant to draught but grows best in areas receiving 16 to 24 in. of precipitation. Sea buckthorn shrubs are also salt-tolerant and thrive in deep, well drained, sandy loam soil with high organic matter and between 6 and 7 pH. The plant is resistant to temperature fluctuations, tolerating from -43 to 40 C; one of the reasons for sea buckthorn to thrive in Canada.

The pollination of the female flowers generally happens in mid-May and after about 100 days (end of August/beginning of September), the fruits are ripe and ready to be harvested. Sea buckthorn berries are orange, oval-shaped, and have an acidic flavour note. Their yield is around 12 to15 lb (5 to 7 kg) per plant or 1.8 to 2.2 tonnes/acre. Fruits are difficult to harvest, making it the main drawback associated with this crop. Manual harvesting is estimated to take as long as 600 h/acre, so mechanical harvesting is the preferred option. Following harvest, sea buckthorn fruits should be immediately processed or destined to commercialization (if sold as fresh berries). If necessary, they can be stored at 4 C for up to two weeks or frozen for long-term preservation.

Sea buckthorn berries are packed with antioxidant compounds and have several application possibilities in the functional food sector. Photo © Angela Troke

Is it worth the effort?

For some, cultivating sea buckthorn may seem like too much effort for a relatively unknown fruit and one of the first questions to emerge is “what to do with sea buckthorn”? Selling the fresh fruit is one option, but segregating sea buckthorn into its many fractions may be more commercially feasible. These small berries can afford a multitude of products with high profit margins. As a starting point, berries can be pressed for juice extraction. With a simple centrifugation process, the juice can be clarified, affording an oil layer that corresponds to about eight to 12 per cent of the pulp’s volume. This premium oil is rich in omega-3 (alpha-linolenic acid, around 30 per cent) and omega-6 (linoleic acid, around 40 per cent) fatty acids, vitamin E, as well as carotenoids, natural pigments with vitamin A activity and antioxidant properties. Seed oil can also be obtained by pressing sea buckthorn seeds, yielding around 13 per cent oil, and commercialized as a high-value functional product for oral consumption or even incorporated into cosmetics due to its moisturizing properties and rich composition of anti-ageing molecules.

In the European and Asian countries where sea buckthorn industries are well-established, pulp and seed oils are the most valuable sea buckthorn products. Drinking sea buckthorn juice may take some adaptation as the berries are fairly sour, but the benefits rely on their high content of vitamin C and carotenoids. Alternative to juice extraction, the berries may either be manually or mechanically separated from the seeds. The pulp can then be frozen or dehydrated to afford a fruit powder to be sold as a functional ingredient for jams, yogurts, and desserts, among others, or even destined for direct consumption. The production of sea buckthorn wine, liqueurs, and spirits is also a promising alternative in light of the surge in fruit-based alcoholic beverages. Hence, sea buckthorn berries may be used in several other products with minimal adaptation for companies processing similar feedstocks. Besides, one of the most interesting aspects of sea buckthorn is that after obtaining its primary products (oil, juice, etc.), the residual fractions still hold considerable amounts of phytochemicals with health-promoting potential.

Sea buckthorn oil is rich in omega-3 and omega-6 fatty acids and vitamin E. Photo © Marina Moskalyuk / Getty

Nothing goes to waste

The scientific literature still lacks a robust database on the composition of sea buckthorn berries grown in North America. Climatic conditions and soil quality are determinant for the chemical composition of fruits and other plant materials. Therefore, each location will have its unique sea buckthorn berry, even within the same country. Our research team was the first to report on the polyphenol composition of sea buckthorn grown in Newfoundland. The defatted pomace (the pressing cake from juice extraction) and seeds were analyzed for their polyphenol content and profile to determine how our sea buckthorn cultivar compares to the ones grown elsewhere.

We found Newfoundland’s sea buckthorn is mainly composed of ellagitannins and gallotannins, which are complex polyphenols, also found in strawberries and blueberries. Besides, the seeds are particularly rich in catechin, the same flavonoid found in green tea. Many of these molecules are only found in the sea buckthorn cultivated in this region. Moreover, the seeds showed higher levels of polyphenols than the flesh, demonstrating promising nutraceutical properties and opening new possibilities for the repurposing of this residual material. After detecting such a wealth of antioxidant substances in sea buckthorn’s pomace and seeds, we set out to evaluate what type of health effects these soups of bioactive compounds could potentially hold. The polyphenols present have shown the ability to reduce the activity of enzymes involved in type 2 diabetes and obesity, while decreasing oxidative damage to LDL-cholesterol and supercoiled DNA, risk factors for heart disease and some types of cancer, respectively. Importantly, the evidence comes from in vitro studies, pending further experimentation involving animal models and humans to confirm such effects. Notwithstanding, the promising nutraceutical power of sea buckthorn berries, their derived products, and even their residues provide opportunities for cultivation and full use of sea buckthorn.

The take home message

Much work remains to be done with the Canadian cultivars of sea buckthorn. Investigating its composition was just a first step in understanding how we can embrace these small berries as a local product and make the most of them. Sea buckthorn has what it takes to be classified as a superfruit and share the same good reputation as blueberries, blackberries, and cranberries, among others. A joint effort between the functional food and nutraceutical industries and academia may lead to the popularization of sea buckthorn, increasing awareness of its health benefits, which would undoubtedly bump up consumer demand for sea buckthorn products.

Fereidoon Shahidi is a university research professor and distinguished scholar at the Department of Biochemistry, Memorial University of Newfoundland (MUN), St. John’s, and Renan Danielski is a postdoctoral fellow in Dr. Shahidi’s Nutraceutical and Functional Food laboratory at MUN. They can be reached via email at fshahidi@mun.ca and rdanielski@mun.ca, respectively.