Abstract

Roland Verhe Vera Van Hoed During the last decade, consumers have become aware that vegetable oils are important parts of a healthy diet due to the health promoting effects of essential fatty acids, and beneficial effects of minor components such as tocopherols, sterols, squalene, and carotenoids. In addition, the market and the demand for functional foods and nutraceuticals has been largely expanded. It is also forecasted that producers of health promoting bioactives from oils will continue to search for additional resources and for efficient and sustainable processing techniques. Although commodity oils are rich sources of fatty acids and bioactives, processing, and refining cause losses in the nutritional value of the oils. Nevertheless, important functional ingredients can be isolated from side-streams during the refining1. Very recently, due to the increasing interest in “organic oils,” and the biodiversity in vegetable and fruit oils, new sources for edible oils and raw materials for cosmetics, especially cosmeceuticals, have been evaluated. These specialty oils from various resources and obtained by advanced processing and refining techniques (e.g., supercritical extraction), are introduced on the market as gourmet and health promoting oils2. Next to the beneficial health properties, these oils are characterized by their specific aroma and taste due to the specific origin and their minimal processing and refining steps. The nutritional value of these oils can be very high due to the presence of ω3-fatty acids and other essential fatty acids, ω3/ω6 ratio, high content of tocopherols, tocotrienols, sterols, antioxidants (polyphenols, squalene, carotenoids, and chlorophyll) 3. The majority of specialty oils are obtained by cold pressing from seeds, nuts, and fruits. Sometimes, specialty oils are produced from waste products from processing of grapes and berries, which leads to a reduction of the waste volumes to be disposed of, and on the contrary, to a valorisation of those waste streams4. In this way, grape seed oils and berry seed oils (cranberry, raspberry, blackberry, kiwi, and other) are now commercially available. Other marketed oils include avocado, camellia, oat, rice bran (extremely rich in γ-oryzanol), hemp, and pumpkin seed oils2. The majority of these oils are sold in fashionable small packages—drawing attention by labeling health promoting properties—and at high prices. These oils are looking very attractive for consumers searching for new taste and for healthy products, and break down the traditional paradigm of commodity oils. Due to their high prices, specialty oils are vulnerable to be adulterated with much cheaper vegetable (commodity) oils, which implies a professional fraud and a danger for consumers' health. Therefore, analytical methodologies to assess their authenticity must be available before these products are marketed. However, specialty oils have a number of disadvantages such as problematic oxidative stability, which is shortening the shelf life. After isolation, a mild refining should be applied involving water washing to remove bitter tasting components (phenolic compounds), disturbing dark colored components (chlorophyll, carotenoids, etc.) and gum deposits followed by a very mild deodorization5. Especially exotic oils obtained from nuts, seeds, and fruits from tropical and subtropical areas should be subjected to careful investigation on the presence of toxic compounds, allergens, and anti-nutritional agents6. In the cosmetic industry, adding specialty oils to the products and advertising this fact on the label attracts the consumers' attention. However, if no scientific literature exists to prove the positive effects on health or skin, this advertising is merely a sales argument without sufficient fundamental background. This background includes first of all, chemical analysis of the composition, completed with in vitro and in vivo studies of the positive and possible adverse health effects of these oils or their components. Such data is well documented for some cases, such as jojoba oil7, and is currently a subject of intensive study for the fruit seed oils, which recently came under attention. Specialty and gourmet oils are excellent additional sources for health promoting food, functional foods, and nutraceuticals, provided that they are readily available at moderate prices, show a high stability with minimal processing, possess an excellent taste and flavor and that they are carefully analyzed for hazardous agents. The danger is that they can be used as a selling argument creating hypes in a rapidly changing market. Roland Verhe Vera Van Hoed

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