With olive oil having been identified as the main source of improved cardiovascular health in the Mediterranean diet, the potential to develop a functional additive using this knowledge is clear. Bionap's HYDROVAS 10, a highly purified hydroxytyrosol extract from olives, is a promising candidate for functionality and food stabilisation.

HYDROVAS 10 is an ingredient, produced from olive fruits via a proprietary Bionap process, that contains highly purified active compounds and is standardised in 10-12% by mass of hydroxytyrosol and tyrosol (see figure, right).

Epidemiological studies have demonstrated that the benefits of the Mediterranean diet on general health, and cardiovascular health in particular, are mainly attributable to the consumption of olive fruits, usually in the form of olive oil. These beneficial effects are due not only to the specific fat composition of the oil but also to the phenolic compounds it contains.

Recently, the European Food Safety Authority (EFSA) confirmed results of research into olives, and issued a scientific statement describing a causal relationship between the intake of olive polyphenols (standardised by the content of hydroxytyrosol and its derivatives) and the protection of blood lipids from oxidative damage in the human body.

A new functional additive

In the past year, the strong antioxidant activity of hydroxytyrosol has attracted much attention from the food industry as a potential new functional food ingredient. In fact, hydroxytyrosol could be used as a 'functional additive' to preserve quality and improve the nutritional properties of food and foodstuffs.

Candidates for a natural antioxidant additive must meet basic safety, sensory and quality requirements. Moreover, they could offset the limits of current antioxidants, such as the cytotoxic effects of BHA and BHT, bitterness or astringency, or limitation in applicability due to hydrophilic or hydrophobic characteristics. Hydroxytyrosol possesses a strong antioxidant effect, and a radical-scavenging and metal-chelating capacity for the ortho-diphenolic group chemical structure. Moreover, hydroxytyrosol is a simple hydrophilic phenol and it can be easily incorporated into aqueous food systems where lipophilic additives cannot act efficiently. For these characteristics, hydroxytyrosol is considered one of the most interesting candidates as a natural additive for foodstuff stabilisation.

A recent study evaluated hydroxytyrosol and some derivatives (alkyl hydroxytyrosol ether derivatives) as potential functional food additives, with promising results.

Furthermore, hydroxytyrosol obtained from olive oil has been already used as an additive in tomato juice and in fish products. In-vitro assays – such as the ferric thiocyanate method – scavenging of DPPH and ABTS free radicals, and inhibition of oxygen consumption have proven that hydroxytyrosol is able to significantly increase the antioxidant capacity of the functionalised tomato juice. The addition of hydroxytyrosol didn't affect the sensory properties of the tomato juice, and it remained stable under extreme storage conditions (temperature and light exposure).

further interesting study has been carried out evaluating the capacity of hydroxytyrosol to prevent oxidative deterioration in fish-lipid (PUFA)-rich foodstuffs. Results showed that hydroxytyrosol was able to increase the oxidative stability in different food systems, such as bulk fish oil, oil-in-water emulsion and frozen minced fish muscle, when it was used at different optimal concentrations for each one, ranging from 10 to 100ppm, and its activity was similar to the synthetic propyl gallate in most of them.

In conclusion, hydroxytyrosol can be considered a good candidate as a natural functional additive not only to improve healthy properties but also to increase and preserve the stability of foods.

References available upon request.