Oleuropein (OLE) and hydroxytyrosol (HT) are olive-derived phenols recognised as health-promoting agents with antioxidant, anti-inflammatory, cardioprotective, antifungal, antimicrobial, and antitumor activities, providing a wide range of applications as functional food ingredients. HT is Generally Recognised as Safe (GRAS) by the European Food Safety Authority (EFSA) and the Food and Drug Administration (FDA), whereas OLE is included in EFSA daily consumptions recommendations, albeit there is no official GRAS status for its pure form.
Formulation | Application | Main Findings | Ref. |
---|---|---|---|
Liposomes | |||
Liposomes with OLE, HT and TYR | Drug-delivery system | ↑ EE% for OLE No cytotoxic effects on human chondrocyte cells |
[30] |
DPPC liposomes with OLE | Beverages | EE: 34% Particle size: 405 nm Stable in commercial lemonade drink over 47 days at 5 °C |
[33] |
Ufasomes with OLE | Claim for food application | ↑ antioxidant activity of encapsulated OLE against oxidative stress induced by H2O2 on CaCo-2 cells | [34] |
Liposomes with phosphatidyl-HT | Claim for food application | Particle size 85 nm; Surface charge: <−25 mV (stable liposomes) | [32] |
Nanostructured lipid carriers | |||
OLE-loaded NLC | Claim for food application | OLE leakage was not observed in the nanocarriers within the 3 months of storage Good stability of OLE-loaded NLC |
[35] |
Emulsions | |||
Lipid emulsions and microemulsions | Claim for food application | Digestibility assay: ↓ Gastric lipolysis of microemulsion compared to emulsions. ↓ Effect of duodenal lipolysis by the dispersion type. | [36][37][36,37] |
OLE-loaded W/O/W | Claim for food application | Emulsions were stabilised for + than 40 days of storage with ↑ hydrophobic emulsifier concentration and ↓ OLE concentration | [38] |
OLE-loaded O/W | Claim for food application | Stable monodisperse oil-in-water O/W was produced when higher hydrophobic triglyceride oils are used | [39] |
OLE-loaded O/W | Claim for food application | ↑ stability due to the surface activity of OLE | [40] |
Nano OLE-loaded W/O/W | Claim for food application | Optimum conditions for formulation: 8% WPC, 1.97% pectin and 8.74% Span 80 EE: 91%; Droplet size: 191 nm; Surface charge: −26.8 mV |
[41] |
O/W, W/O/W and GDE with HT and perilla oil | Claim for food applications | Emulsions structurally stable at 4 °C up to 22 days. HT losses up to 24% throughout the storage of GDE → ↓ antioxidant activity of the emulsion. No lipid oxidation during storage. |
[42] |
GDE with HT | Animal fat replacing | Physical properties: ↑ formation of weaker gels; no significant loss levels until 30 days; minimal changes in colour and pH of W/O/W during storage. Oxidation: systems little prone to oxidation even at 30 days. Biological activity: ↑ antioxidant and ↑ antimicrobial activity |
[43] |
HT in W/O/W enriched in chia oil | Meat supplementation | Presence of HT: ↑ oxidative stability: ↑ DPPH free radicals scavenging; ↑ FRAP; ↓ TBARS | [44] |
Formulation | Application | Main Findings | Ref. |
Cellulose microcapsules with HT | Claim for food application | EE: 82.4–88.1% Particle size: 156.6–304.0 µm Microcapsules with HT are gastro-resistant and retain > 50% of their antioxidant capacity in simulated GI fluids. |
[53] |
Starch granules with HT and probiotics | Nutraceuticals | Resistant against GI tract conditions and stable up to 6 months of storage under refrigeration. ↓ HT bioavailability by the administration of live L. plantarum bacteria with the olive phenol-containing extract, compared to the extract alone. |
[54] |
Starch nanocrystals or nanoparticles in a PVA film with HT | Active packaging | HT migrated values for all formulations ≤ migration limits for food contact materials. Gradual release of HT during 21 days. Highest gradual release for films with starch nanoparticles. ↑ antioxidant activity for all ternary formulations over time. |
[55] |
Poly(ε-caprolactone)-based NC and montmorillonite, Cloisite30B films with HT | Active packaging | HT ↑ poly(ε-caprolactone) crystallinity, ↓ thermal stability and plasticizing effect. Interaction of HT-Cloisite30B led to a prolonged release of the HT. |
[56] |
Pectin plus fish gelatin composite films with HT and DHPG | Strawberry preservation | ↑ stretching capacity and resistance to breakage. The edible film preserved strawberries with a significant delay in visible decay. | [57] |
Meat preservation | ↓ lipid oxidation in raw beef meat during refrigerated storage. Film with adequate mechanical and oxygen barrier properties. Film with beeswax ↓ lipid oxidation and ↓ the oxygen barrier capacity. | [58] | |
MD-OLE and IN-OLE | Claim for food application | Protection of OLE from GI conditions. | [59] |
Eudraguard® protect with HT | Claim for food application | Spherical non-aggregate particle (particle size: 230 nm) Loading capacity of HT: 38% |
[60] |
Formulation | Application | Results | Ref. |
---|---|---|---|
Oleuropein | |||
α-CD·OLE, β-CD·OLE and Ɣ-CD·OLE | Claim for food application | OLE form binary complexes (1:1) with the three types of CDs β-CD is the most effective for complexation. |
[71] |
β-LG·OLE | Claim for food application | ↑ stability of formed complexes and validity of docking results for β-LG·OLE. | [72] |
OLE·ALA | Claim for food application | OLE binds to ALA mainly via electrostatic, van der Waals and hydrogen bonds. | [73] |
Hydroxytyrosol and Oleuropein | |||
β-CD·HT, β-CD·OLE and β-CD·TYR | Claim for food application | No OH group of HT and OLE is shielded in the β-CD cavity Antioxidant activity: β-CD·HT > β-CD·OLE > β-CD·TYR. |
[74] |
Hydroxytyrosol | |||
β-CD·olive biophenols | Claim for food application | ↓ bitter taste and preserves them against chemical and physical decomposition reactions during storage. | [75] |
β-CD·HT, HP-β-CD·HT |
Claim for food application | Insertion of the HT through the narrower face of the CDs. ↑ antioxidant capacity and photoprotection of HT. |
[76] |
β-CD·HT | Food industry | ↓ HT bioaccessibility (−20%) and absorption (−10%) in presence of foods (7 mg of HT in the meal). β-CD did not affect bioaccessibility and absorption. |
[77] |
β-CD·HT | Claim for food application | β-CD and drying processes do not affect the efficiency of HT to reduce the DPPH radical. | [78] |
HT/DHPG-soluble and insoluble dietary fiber of apple cell wall | Dietary fiber | Non-covalent interaction between phenols and the apple cell wall fibers. Antioxidant activity of HT/DHPG was not altered after complexation with apple cell wall fibers and after a simulated gastrointestinal digestion. | [79] |