When manufacturing fruit juice, the food industry produces large amounts of press cakes  containing a range of useful compounds for the skin, such as polyphenols known for their antimicrobial and antioxidant properties. Until now, the industry has largely confined itself to extracting seed oil from press cakes. Despite the potential for new product concepts, no other high-value-added products are currently made from these press cakes. This is why VTT has been searching the best way to extract actives from fruit by-products, and more particularly from Nordic berry seeds.
Actually, VTT has developed various methods to extract and enrich these actives.
For berries with large seeds and various fruits, a specific sanding method can be used. For example, 20% of a cloudberry seed’s weight can be sanded using this method to recover the husk. “One kilogramme of berries yields 10 grammes of seed husk fractions, but a small amount suffices for cosmetics products,” explains the centre.
Then, active substances from seed husk fractions are extracted using the so-called hydrothermal extraction technology. “The whole process is free from no toxic agents or solvents,” claims VTT. The final product tends to be light-coloured, powdery, water-soluble, food-grade fractions. After sanding, seed oil can be extracted from the remaining seeds. VTT has optimised and patented the process for a variety of berry seeds.
As far as small-seed berries such as blueberries are concerned, their useful compounds can be extracted using a wet milling method developed by VTT.
Natural anti-microbial actives
One of the most interesting properties of the substances extracted from the husks of berry seeds is their ability to prevent the growth of harmful microbes. Indeed, research conducted by VTT show the new actives may have selected effects on the numerous microbes inhabiting the human skin.
“Berry seed husks contain large amounts of antimicrobial compounds which can help to maintain a natural microbial balance in the skin, by suppressing the growth of harmful microbes while beneficial ones flourish. This is based on nature’s way of protecting seeds from threats such as fungi,“explains Riitta Puupponen-Pimiä, Principal Scientist at VTT.”We have investigated how the microbes typically found in human skin and those that hide in cosmetic products react to polyphenols contained in berries. At a general level, you could say that seed husk fractions and the resulting extracts prevent harmful microbial growth in the skin, but do not suppress the growth of good microbes," she adds.
These findings could be of high interest for the cosmetics industry which is looking for natural alternatives to synthetic preservatives as well as for innovative methods to protect the skin’s microbiota.
"The maintenance of healthy skin and the replacement of synthetic preservatives by natural compounds is one of the major trends in the cosmetics market,” confirms Riitta Puupponen-Pimiä.
Cloudberries and Arctic brambles
VTT investigated the properties of a large array of Finnish and Nordic berries and found cloudberries and Arctic brambles to produce the most efficient seed fraction extracts to inhibit the growth of harmful microbes. These berries, which belong to the Rubus genus, contain high levels of polyphenols called ellagitannins, which are known for their anti-microbial effects.
Extract from sea buckthorn seed fractions has also proven effective. Sea buckthorn seed husks are also rich in polyphenols known as procyanidins, a kind of tannin.
VTT’s research has shown that, in addition to polyphenols, seed press cakes contain many other health-promoting compounds making them a very interesting and sustainable source of active ingredients for the food and cosmetic markets. “Most of the thousands of kilogrammes of seed cake produced could be used for purposes other than feed,” concludes the research centre.