Table 2.
Innovative techniques applied in the extraction of bio-active compounds using vegetable oils as solvents.
| Technique | Matrix | Experimental Remarks | Reference |
|---|---|---|---|
| Ultrasound | Olive leaves (Olea europaea L.) | Solid-liquid oil enrichment (10:1 a, 20 min, 25 °C) assisted by ultrasound (225 W, 50% amplitude, duty cycle 0.5 s) produced edible oils with better quality than non-ultrasonicated oils. | [113] |
| Basil leaves (Ocimum basilicum L.) | Ultrasound-assisted aromatisation of 1L of olive oil with fresh basil leaves of different amounts. The essential oil contained in the basil leaves was directly extracted into the olive oil without any intermediate stage, which led to an aromatised olive oil in few minutes compared to several hours required in the conventional maceration. | [114] | |
| Olive leaves (Olea europaea L.) | Olive oil enrichment with phenolic compounds (e.g., oleuropein) from olive leaves by ultrasonic maceration (60 W, 16 °C and 45 min). The highest total phenolic content (414.3 ± 3.2 mg of oleuropein equivalent/kg of oil), oleuropein (111.0 ± 2.2 mg/kg of oil) and α-tocopherol (55.0 ± 2.1 g/kg of oil) concentrations obtained by optimized ultrasound-assisted extraction proved its efficiency compared to the conventional solid-liquid extraction. | [115] | |
| Sea buckthorn pomace (Hippophae rhamnoides) | Ultrasound-assisted extraction (power 0.67 W/g oil and 35 °C) has been used to greatly improve the direct enrichment of edible oils (sunflower, rapeseed, olive, and soya) with carotenoids from sea buckthorn pomaces in terms of quantity and process time (from 33.83 mg/L extract in 90 min obtained by conventional extraction to 51.64 mg/L extract in only 20 min by ultrasound). | [116] | |
| Carrot (Daucus carota L.) | Ultrasound-assisted extraction (carrot/oil ratio 2:10, 22.5 W, 40 °C and 20 min) using sunflower as alternative solvent to hexane obtained highest β-carotene yield (334.75 mg/L) in 20 min, while conventional solvent extraction obtained a similar yield (321.35 mg/L) in 60 min. | [82] | |
| Carrot residue (obtained after juice extraction) (Daucus carota L.) | Extraction using ultrasonic horn (20:0.3 a, 100 W, 50 min, 50 °C), the maximum extraction yield of β-carotene was 83.32% while that was 64.66% when using ultrasonic bath. | [117] | |
| Pomegranate peels (Punica granatum L.) | Sunflower and soy oil were used as alternative solvents to study the effect of various parameters on the yield between ultrasound and conventional extraction, in which the optimal conditions for achieving maximum yield of carotenoids from pomegranate peels were 10:1 a, 30 min, 51.5 °C, 58.8% of amplitude level and sunflower oil solvent. | [118] | |
| Microwave coupling ultrasound | Vegetables, herbs, spices or fruits | Time-saving aromatizations of olive oil with different compounds from various plants were improved by ultrasound and microwave. The resulting flavoured oils are increasingly appreciated by European consumers. | [34] |
| Sweet Pepper (Capsicum annuum) | Compared to traditional infusion or maceration (10:1 a, 7 days), For the ultrasonic treatment, samples of olive oil were prepared by adding 10% and 20% dried chili pepper and subjected to ultrasound-extraction for 10 or 20 min. For microwave extraction, samples were added with 20% chili powder and treated for 10, 30 or 60 s. The production of flavored olive oils by using technologies such as microwave and ultrasound-extraction could allow the production of high quality oils, with fast and cost-effectively methods. | [119] | |
| Microwaves | Aromatic plants | A patented method for the extraction of aromas from aromatic plants using microwave is disclosed. | [83] |
| Olive leaf | Liquid-liquid enrichment with microwave phenolic extract (1:1 a, 15 min, 600 units/min). Olive oil was the most enriched. Enrich oils obtained a better taste quality. | [120] | |
| Olive waste (orujo) | Solid-liquid and liquid-liquid oil enrichments (1:1 a, 30 min) with dilutions of microwave phenolic extracts. The phenol distribution factor increases with high level of unsaturated fatty acids whereas high-saturated fatty acid content decreases this factor. | [121] | |
| Fresh vegetable materials | The present invention relates to a method for obtaining an oily extract of plants from plant material comprising the steps of mixing the plant material with a fat, heating (microwave at 0.1 to 5 W/g of oil and plant material mixture) said mixture and recovery of the oily extract. The present invention finds particular application in the field of the production of special extracts, scent extracts, extracts perfuming, supply of raw materials, olfactory raw materials, active ingredients, for example in cosmetics and/or dermatology. | [122] | |
| Daylily (Hemerocallis fulva) | The invention relates to the use of an oily composition comprising a lipophilic extract of daylily as an active ingredient for the preparation of a topical cosmetic composition intended to improve complexion radiance and/or to even skin tone, to a non-therapeutic cosmetic skin treatment method using such a cosmetic composition. The extract is obtained by the technique of heating by microwaves using avocado oil and rose hip oil. | [123] | |
| Supercritical fluids | Tomato (Solanum lycopersicum L.) | Extraction of lycopene from tomato using SC-CO2 extraction in the presence of vegetable oil as co-solvent. The pre-treatment of raw material (drying, grinding and screening) is necessary in order to obtain significative yields of the extractable lycopene. The operative parameters (flow, time, pressure, etc.) are also crucial for better yields and the best operative conditions found are the following: pressure 450 bar, temperature 65–70 °C, CO2 flow rate 18–20 kg CO2/h, average particle sizes of the material of about 1 mm, presence of a vegetable oil as co-solvent (about 10%). | [97] |
| Red pepper (Capsicum frutescens L.) | Enriched oils with supercritical CO2 extracts (0.5 wt %) at low pressure and velocity (40 °C, 10 min) performed stable. | [124] | |
| Carrot (Daucus carota L.) | Employing canola oil as a continuous co-solvent in SC-CO2 extraction is a novel and efficient technique for the recovery of carotenoids from natural materials. | [95] | |
| Microalgae (Haematococcus pluvialis) | Soybean oil and olive oil used as co-solvents were investigated for SC-CO2 extraction of astaxanthin from H. pluvialis. The result of the SC-CO2 extraction of astaxanthin with the presence of 10% by volume olive oil showed the higher increase in the amount of astaxanthin extracted. | [112] | |
| Marigold (Tagetes erecta L.) | SC-CO2 extraction of lutein esters from marigold with soybean oil as a co-solvent was performed. Results showed that the data could be well fitted to a second-order polynomial model with a R2-value of 0.9398. The model predicted that the optimal conditions were 35.5 MPa, 58.7 °C, CO2 flow rate of 19.9 L/h with 6.9% of soybean oil as a co-solvent, and under such conditions, the maximum yield of 1.04 g lutein/100 g marigold could be achieved. | [100] | |
| Marigold (Tagetes erecta L.) | Medium-chain triglycerides (MCTs), sunflower seed oil, soybean oil, rapeseed oil and n-hexane were used as co-solvents to promote supercritical carbon dioxide (SC-CO2) extraction of lutein esters from marigold (Tagetes erecta L.). The optimum extraction conditions within the experimental range were predicted to be: extraction pressure of 46.8 MPa, temperature of 65.9 °C and MCT concentration of 1.5% (w/w of CO2), with a CO2 flow rate of 10 kg/h and extraction time of 3 h. The maximum yield of lutein esters under these conditions was predicted to be 1.3 g/100 g marigold. | [101] |
a Oil to solid material ratio (mL/g); b Oil to liquid extracts ratio (mL/mL).