Table 1.
Sources of natural bioactive ingredients and extraction conditions for the development of novel functional virgin olive oil (VOOs).
| Source/Ingredient | Extraction Method and Conditions | Observed Functional Effect in Enriched Olive Oil | Reference |
|---|---|---|---|
| Olive leaves | SLE: directly in the oil (organic-solvent free), dynamic extraction chamber, USAE (25 °C, 20 min) | Increased oxidative stability | [40] |
| SLE and LLE with ethanol, MAE (8–10 min, 200–400 W) | Increased oxidative stability | [41,42,43] | |
| Olive pomace | SLE: ethanol/water (70:30), overnight stirring | Increased oxidative stability | [44] |
| SLE: methanol and 1,2-propanediol, hydrolyzate (HCl 2 M, 100 °C for 1 h) | Increased phenolic content in fried foodstuffs | [45] | |
| LLE with ethyl acetate (for vegetative water) and SLE with ethanol/water (80:20; for solid residue) | Increased oxidative stability and antioxidant capacity | [38] | |
| ASE with ethanol/water (80:20 at 80 °C) | Increased oxidative stability and antioxidant capacity | [42] | |
| ASE with ethanol/water (80:20 at 80 °C), enrichment with 0.3% of emulsifier (lecithin or monoglycerides) and USAE | Lecithin is more effective increasing oxidative stability and antioxidant capacity | [47] | |
| Olive leaf and pomace | Aqueous extracts with or without the use of lecithin | Increased oxidative stability | [48] |
| Olive oil | Semi-preparative HPLC | Increased antioxidant capacity | [49] |
| Technological conditions during crushing (milling intensity) and malaxation (temperature and time) | Increased oxidative stability and antioxidant capacity | [50] | |
| Red pepper | Infusion: 10%–20% up to 30 days | Reduced oxidative stability | [51] |
| SFE at 40 °C and 15–23 MPa | Reduced oxidative stability | [52] | |
| Hot pepper, garlic, oregano and rosemary | Infusion: 20–40 g/L up to 7 months | Increased oxidative stability | [53] |
| Rosemary, lavender, sage, menthe, basil, lemon and thyme | Infusion: 5% for 15 days | Increased oxidative stability for rosemary > thyme and > lemon | [54] |
| Garlic, lemon, oregano, hot pepper, and rosemary | Co-processing (pressing, crushing and malaxation): 3%–20% into olives | Reduced stability, expect garlic Higher antioxidant activity (rosemary) |
[55] |
| Basil | Infusion: 15% with USAE (1 W/cm2) for 15 min | Not determined | [56] |
| Lemon and thyme | Infusion: 20% during 2 months | Unchanged oxidative stability | [57] |
| Thyme and olive pomace | ASE: ethanol/water (80:20) at 80 °C and up to 1500 psi | Increased antioxidant capacity | [36] |
| Oregano | Addition of 0.05% of essential oil | Increased oxidative stability | [58] |
| Infusion by stirring at 1000 rpm for 3 h | Increased oxidative stability | [59] | |
| Thyme | Addition of 200 mg/L of essential oil | Not clear effect on oxidative stability | [60] |
| Garlic, hot chili peppers, laurel, oregano and pepper | Infusion: 10 g/L during three months at room temperature | Increased oxidative stability | [61] |
| Sweet lemon and sweet orange peels | Infusion: 1%–5% at 60 °C for 40 days | Increased antioxidant capacity. Reduced oxidative stability | [62] |
| Basil, chili and garlic | Infusion: 10%–20%, 7 days stirring at 15–18 °C vs. combined malaxation | Antioxidant activity was significantly lower in the oils obtained by infusion | [63] |
| Caraway | 1.5% at room temperature, infusion for 6 h vs. USAE for 30 min | Increased oxidative stability (OSI, but not for PV or Ks) | [64] |
| Thyme and oregano | Infusion (10 g/L for 15 days at room temperature) vs. co-malaxation (10 g/kg with or without 6 min USAE, before kneading) | Increased antioxidant capacity (especially with thyme) | [65] |
| Citrus fruits or peel | 0.5%–5% by co-processing (milling and/or malaxation) | Increased antioxidant capacity | [66,67] |
| Fruits (apple, lemon and orange), spices (rosemary, thyme, basil and oregano) and leaves (rocket) | 0.5%–5% by co-processing (milling and/or malaxation) | Statistically significant differences in sensory testing, except in apple and rocket | [68] |
| Lycopene | SLE with tomato pulp and VOO at high mechanical mixing (patented) | Enhanced antioxidant status in humans | [35,69] |
| Co-milling of tomato seed or skin and olives | Significant enrichment in carotenoids, especially in lycopene | [70] |
Oxidative stability or shelf-life, determined by peroxide value (PV), Ks or oxidative stability index (OSI/Rancimat). Antioxidant capacity, determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH), oxygen radical antioxidant capacity (ORAC) or 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. ASE: Accelerated extraction system; HPLC: High-performance liquid chromatography; LLE: Liquid–liquid extraction; MAE: Microwave assisted extraction; SFE: Supercritical fluid extraction; SLE: Solid–liquid extraction; USAE: Ultrasound assisted extraction.