Extraction and isolation of plant bioactives

Natural bioactive compounds derived from plant materials play an important role in human health. It is desirable to find the most suitable methods for extracting and isolating those compounds from plant matrices. Techniques for extraction and isolation of bioactive compounds have been developed over the years. This chapter presents a general overview of the techniques involved in extraction and isolation of bioactive compounds from plants. Particularly, traditional extraction methods (steam distillation and solid liquid extraction), novel extraction techniques (microwave assisted extraction, ultrasound assisted extraction, supercritical fluid extraction, and pressurised fluid extraction) and isolation techniques (ion-exchange and high performance liquid chromatography) are reviewed. Comparisons of different extraction techniques, various applications and recommendations with specific examples for each technique are also discussed. Furthermore, the different evaluation techniques in vitro and in vivo for bioactivities and antioxidant activities of crude extracts or isolated/purified compounds are also presented

Effects of pre-treatments on the yield and carotenoid content of Gac oil using supercritical carbon dioxide extraction

The effects of air-drying temperature, particle size and enzymatic pre-treatment on the oil yield and content of carotenoids in the resultant Gac oil using supercritical CO₂ extraction method were investigated. It was found that the highest oil yield was obtained when using the enzyme concentration at 0.1% (w/w) for pretreatment before air-drying. Furthermore, the content of carotenoids was also enhanced by suitable drying temperature and the particle size. High oil yield (34% g/g) and high content of β-carotene (83 mg/100 mL oil) and lycopene (508 mg/100 mL oil) were obtained using the drying temperature of 50°C and particle size of 0.45 mm as pre-treatments prior to SC-CO₂ extraction at pressure of 200 bar and extraction temperature of 50°C. Results also indicated that the most suitable extraction time was 120 min. It was concluded that Gac oil containing high amount of carotenoids could be extracted using the chosen air-drying temperature, particle size, enzymatic pre-treatment and extraction time

Effects of spray drying conditions on the physicochemical and antioxidant properties of the Gac (Momordica cochinchinensis) fruit aril powder

Gac fruit aril has an attractive orange red colour and very high level of carotenoids, giving it exceptional antioxidant properties. However, spray drying of this material has not been successful and malto dextrin is considered as a suitable drying aid to preserve its colour and antioxidant properties. This paper reports the effects of inlet drying air temperature (120, 140, 160, 180 and 200 °C) and maltodextrin addition (10%, 20% and 30%) on the physicochemical and antioxidant properties of the Gac aril powder. Moisture content and bulk density, colour characteristics, total carotenoid content (TCC), encapsulation efficiency and total antioxidant activity (TAA) were significantly affected by maltodextrin concentration and the inlet air temperatures. However, pH, aw and water solubility index were not significantly influenced by the spray drying conditions. Overall, a good quality Gac powder in terms of colour, TCC and TAA can be produced by spray-drying at inlet temperature of 120 °C and adding maltodextrin concentration at 10% w/v

Effects of formulations on Gac oil emulsion stability for microencapsulation

The objective of this study was to determine the most suitable formulations for a high stability Gac oil emulsion and a high retention within the oil of lycopene and β-carotene contents. We investigated the effects (i) of the concentration of the wall materials (WPC/GA, 7/3, w/w) (20, 30 and 40%, w/w), (ii) the ratios of Gac oil to wall material (2:1, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7 and 1:8, w/w) on the emulsion stability and retention of lycopene and β-carotene contents at different storage temperatures (4, 22 and 37 °C), as well as on viscosity, pH, mean particle size and particle size distribution. Results showed that emulsions obtained using the ratios of 1:5 up to 2:1 and a concentration of 30% remained highly stable for at least 24 h at the storage temperatures. Among these samples, the retention of carotenoids in the emulsions formulated with the ratios of 1:3, 1:4, and 1:5 was found to be the highest. At those formulations, emulsions had viscosity of < 30 cP, mean particle size of < 10 μm and pH of 5.7 to 5.8. It is concluded that emulsions with excellent stability, low viscosity, and small and uniform particle sizes can be formulated for microencapsulation

Microencapsulation of gac oil by spray drying: optimization of wall material concentration and oil load using response surface methodology

The objective of this study was to optimize the wall material concentration and the oil load on the encapsulation of Gac oil using spray drying by response surface methodology. Results showed that the quadratic polynomial model was sufficient to describe and predict encapsulation efficiencies in terms of oil, ß-carotene, lycopene, peroxide value (PV), moisture content (MC), and total color difference (ΔE) with R 2 values of 0.96, 0.95, 0.86, 0.89, 0.88, and 0.87, respectively. Under optimum conditions (wall concentration of 29.5 % and oil load of 0.2), the encapsulation efficiencies for oil, ß-carotene, lycopene, PV, MC, and ΔE were predicted and confirmed as 92 %, 80 %, 74 %, 3.91 meq/kg, 4.14 % and 12.38, respectively. The physical properties of the encapsulated oil powders obtained by different formulations were also determined. It was concluded that the protein-polysaccharide matrix as the wall material was effectively used for spray-drying encapsulation of Gac oil

Effects of Gac aril microwave processing conditions on oil extraction efficiency, and β-carotene and Lycopene contents

The effects of Gac oil extraction conditions including microwave power, microwave time, steaming time and hydraulic pressure on extraction efficiency (EE), and β-carotene and lycopene contents were studied. It was found that the EE, and β-carotene and lycopene contents could be enhanced by suitable extraction conditions. Microwave drying was found to be better than air drying for pretreatment. Moisture content after drying and steaming between 8 and 11% (wt/wt) were best for pressing. Results showed that the most suitable conditions for Gac oil extraction from 900 g samples were microwave power of 630 W, microwave time of 65 min, steaming time of 20 min and hydraulic pressure of 170 kg/cm2. Under these conditions, the highest EE of 93% was achieved while Gac oil contained the highest content of β-carotene and lycopene at 140 and 414 mg/ 100g, respectively

A storage study of encapsulated gac (Momordica cochinchinensis) oil powder and its fortification into foods

This study investigated the effects of different storage conditions, temperatures of -20, 10, room temperature (RT), 40 and 63°C for up to 12 months in the presence or absence of air and light, on the stability of an encapsulated gac (Momordica cochinchinensis) oil powder. A stability trial of the encapsulated oil powder incorporated into yoghurt, pasteurised milk and cake mix stored at 4 ± 0.5°C and RT for different storage times was also carried out. The results showed that a progressive degradation of colour, β-carotene and lycopene, and a progressive increase in surface oil content and peroxide value (PV) occurred in the encapsulated powders with increasing storage temperatures and storage times. However, the degradation was much less when the encapsulated powder was stored at low temperature in the absence of air and light. The degradation of β-carotene and lycopene in all samples during storage fitted a first-order reaction. The sorption curves of the encapsulated powders at 10, 30 and 40°C were fitted with BET and GAB models. The results also showed that the encapsulated gac oil powder could be successfully incorporated into food products in terms of retention of colour, β-carotene and lycopene, and low PV

Effect of drying pre-treatments on the yield and bioactive content of oil extracted from Gac Aril

Gac fruit (Momordica cochinchinensis Spreng) aril contains high levels of bioactive compounds including β-carotene, lycopene and fatty acids. Therefore, it is important to find an extraction method of Gac oil resulting in the highest content of bioactive compounds. The effects of microwave and air-drying pre-treatments of Gac aril prior to hydraulic pressing and Soxhlet extraction on the oil yield, nutrients and chemical properties of the oil were compared. Results showed that the highest oil yield could be obtained when the aril was microwave-dried before Soxhlet extraction. This finding was explained by microstructural changes of the dried arils. Microwave-drying prior to pressing resulted in the highest content of β-carotene (174 mg/100 mL) and lycopene (511 mg/100 mL) in the oil extract. Oleic acid (48%) and linoleic acid (18%) were found to be the dominant fatty acids in the oil extracts. Gac oil with the lowest acid (0.69 mg KOH/g) and peroxide values (1.80 meq O2/kg) was extracted when microwave-drying was applied prior to pressing. It can be concluded that the microwave drying pre-treatment before pressing was better than the air-drying pre-treatment for extracting Gac oil of high quality

Ultrasound-assisted aqueous extraction of oil and carotenoids from microwave-dried Gac (Momordica cochinchinensis spreng) aril

The study aimed to optimise the ultrasound-assisted aqueous extraction of oil, β-carotene and lycopene from powdered microwave-dried gac arils. Ultrasound power, extraction time, powder particle size and the ratio of water to gac powder during the extraction, the centrifugal force used to recover the extracted components were investigated. Microwave-drying followed by aqueous extraction without ultrasound-assistance and air-drying followed by aqueous extraction with or without ultrasound-assistance was also carried out for comparisons. The gac material left behind after the extractions was also investigated using scanning electron microscopy (SEM). The results showed that ultrasound power of 32 W/g of aril powder, extraction time of 20 min, powder particle sizes of 0.3-0.5 mm, a ratio of water to powder of 9 g/g and a centrifugal force of 6,750Ãg gave optimal extraction efficiencies for oil (90%), β-carotene (84%) and lycopene (83%), and the oil had a low peroxide value (PV) of 2.2 meq/kg. The SEM analysis confirmed that the combination of microwave-drying followed by ultrasound-assisted aqueous extraction caused strong disruption of the gac aril cellular structures, which was consistent with the high extraction of oil, β-carotene and lycopene obtained with the combination. It was concluded that gac oil containing high amounts of β-carotene and lycopene and having a low PV could be extracted using microwave-drying and ultrasound-assisted aqueous extraction