Improved lycopene extraction from tomato peels using cell-wall degrading enzymes

Four commercial enzyme preparations with pectinolytic, cellulolytic and hemicellulolytic activities were tested for their ability to enhance lycopene extraction from tomato peels. Screening experiments were performed at 25 °C by subjecting the peels to a 4-h enzyme incubation followed by 1-h hexane extraction. Peclyve EP and LI were the most efficient, with an almost 20-fold increase in extraction yield. Peclyve LI was used to evaluate the influence of solvent type and enzyme incubation time on lycopene recovery. Hexane, ethyl acetate and the mixture hexane/acetone/ethanol 50:25:25 (v/v) were used as solvents. Under the best extraction conditions (1-h enzyme incubation followed by a 3-h solvent extraction at 40 °C) up to 440 mg of lycopene per 100 g of dry tomato peels were obtained. The percentage recoveries were in the range of 3–30%, for the untreated peels, and 77–98% for the enzymatically treated material.     

Recovery of colorants from red prickly pear peels and pulps enhanced by pulsed electric field and ultrasound

The aim of this work was to evaluate the potential of the non-conventional pre-treatments; pulsed electric fields (PEFs) and ultrasounds (USNs), to enhance the extraction of red colorants from red prickly pear (Opuntia stricta Haw.) peels and pulps. The overall goal was to valorize the thick part of the fruit, being discarded for fruit's consumption. PEF and USN treatments were first optimized using fruit slices, followed by a supplementary aqueous extraction (+ SAE) up to 1 h. The optimal conditions were then applied for peels and pulps, separately. Results showed that PEF + SAE and USN + SAE enhanced significantly the extraction of red colorants (betanin/isobetanin), compared to untreated tissues. Promising results for colorants recovery were obtained from fruit peels, using both pre-treatments, compared to that obtained from pulps, and without pre-treatment. Scanning electron microscopy revealed cell denaturation after PEF and USN pre-treatments, which can provide better recovery of the intracellular compounds with less impurity.Industrial relevanceWastes and by-products generated during fruit processing constitute a great source of high-added value compounds, which have the potential to be used as food additives and/or as nutraceuticals. Opuntia fruits constitute a great source of bioactive compounds. In particular, Opuntia fruit processing by-products are interesting as they contain a great amount of potential food additives, including food colorants (i.e. betanin/isobetanin), thus constituting an important alternative to replace synthetic colorants that have been restricted by governmental organizations. In this line, pulsed electric field and ultrasounds are proposed in this work as promising technologies for the enhancement of the extraction of colorants from red prickly pear peels and pulps.     

Recovery of carotenoids from tomato processing by-products – a review

Industrial tomato processing generates large amount of low-value by-products, primarily used as livestock feed or disposed of; however, being a rich source of natural carotenoids, tomato waste can be used to produce high value-added products for food, cosmetics, or pharmaceutical applications. The objective of this review is to summarize and give an overview of the extraction methods available for the recovery of carotenoids and, especially, lycopene from tomato processing by-products. Organic solvent extraction techniques are presented and the effect of extraction conditions on carotenoids recovery is evaluated. In particular, the use of Ultrasound Assisted (UAE), Microwave Assisted (MAE), Enzyme-Assisted (EAE) and Extraction at High Pressure (HPE) for the recovery of carotenoids is assessed. Also, this review examines the efficiency of Supercritical Fluid Extraction (SFE) and in particular the effect of process parameters on carotenoid recovery from industrial tomato waste.     

Improving the pressing extraction of polyphenols of orange peel by pulsed electric fields

The influence of pulsed electric field (PEF) treatment on the extraction by pressing of total polyphenols and flavonoids (naringin and hesperin) from orange peel was investigated. A treatment time of 60 μs (20 pulses of 3 μs) achieved the highest cell disintegration index (Zp) at the different electric field strengths tested. After 30 min of pressurization at 5 bars, the total polyphenol extraction yield (TPEY) increased 20%, 129%, 153% and 159% for orange peel PEF treated at 1, 3, 5 and 7 kV/cm, respectively. A PEF treatment of 5 kV/cm to the orange peels increased the quantity of naringin and hesperidin in the extract of 100 g of orange peels from 1 to 3.1 mg/100 g of fresh weigh (fw) orange peel and from 1.3 to 4.6 mg100 g fw orange peel respectively. Compared to the untreated sample, PEF treatments of 1, 3, 5 and 7 kV/cm increased the antioxidant activity of the extract 51%, 94%, 148% and 192%, respectively.The results of this investigation demonstrate the potential of PEF as a gentle technology to improve the extraction by pressing of polyphenols from fresh orange peel. This procedure enhances the antioxidant capacity of the extracts, reduces extraction times and does not require using organic solvents.Industrial relevanceProcessing of orange fruits to obtain fresh juice or citrus-based drinks generates very large amounts of byproduct wastes, such as peels that are a rich source of polyphenols mainly flavonoids. Extraction of these compounds from orange peels is a crucial step for use of these compounds in the food and pharmaceutical industries as antioxidants. PEF-assisted extraction by pressing of polyphenols from fresh orange peels stands as an economical and environmentally friendly alternative to conventional extraction methods which require the product to be dried, use large amounts of organic solvents and need long extraction times.     

番茄果皮中番茄红素的超临界二氧化碳流体萃取

本项研究表明：超临界二氧化碳流体萃取能够作为传统的有机试剂萃取的替代方法有效地从番茄果皮组织中萃取番茄红素等类胡萝卜素。在本项研究中，多种有机试剂被用来对样品组织进行预处理。这种预处理可明显地提高超临界流体萃取的效率。用四氢呋喃对组织进行预处理后，超临界流体萃取物中总类胡萝卜素的含量比丙酮-乙醚萃取物的高31％，其中番茄红素占90％。这一流程可以考虑被应用到工业生产中去。     

The effect of Pulsed Electric Field as a pre-treatment step in Ultrasound Assisted Extraction of phenolic compounds from fresh rosemary and thyme by-products

Emerging extraction techniques, including pulsed electric field (PEF) and ultrasound (US), are attracting considerable interest in the recovery of bioactives. Though, limited work has focused on PEF application as pre-treatment for US assisted extraction to enhance the release of phenolics from herbs. Hence, the present study investigated the use of an optimized PEF pre-treatment to enhance the recovery of phenolics from fresh rosemary and thyme by-products in a subsequent US assisted extraction step. Total phenolic content (TPC), 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP) were assessed as an index of extraction efficacy. Qualitative and quantitative analyses were performed through liquid chromatography-mass spectrometry analyses to evaluate the influence of the methods on individual phenolic compounds and the formation of potential derivatives. The results indicated that in a number of cases PEF pre-treatment enhanced (p < 0.05) the recovery of phenolic compounds and antioxidant capacity compared to US individually.     

Extraction of anthocyanins from grape by-products assisted by ultrasonics,high hydrostatic pressure or pulsed electric fields: A comparison

Extracts from grape by-products contain bioactive substances such as anthocyanins which could be used as natural antioxidants or colourants. The effect of heat treatment at 70 °C combined with the effect of different emerging novel technologies such as ultrasonics (35 KHz), high hydrostatic pressure (600 MPa) (HHP) and pulsed electric fields (3 kV cm^− 1) (PEF) showed a great feasibility and selectivity for extraction purposes. After 1 h extraction, the total phenolic content of samples subjected to novel technologies was 50% higher than in the control samples. Therefore, the application of novel technologies increased the antioxidant activity of the extracts being the extractions carried out with PEF four-fold, with HHP three-fold and with ultrasonics two-fold higher than the control extraction. In addition, the extraction of individual anthocyanins was studied showing a selective extraction based on the glucose moieties linked to the anthocyanidins; anthocyanin monoglucosides were better extracted by PEF, whereas the acylated ones were extracted by HHP.Industrial relevanceThis study examines the feasibility of different emerging technologies such as high hydrostatic pressure, pulsed electric fields and ultrasonics as potential extraction methods for bioactive substances from grape by-products. Grape by-products represent a low-cost source of valuable bioactive compounds such as anthocyanins, with great industrial applications as colourants or nutraceuticals. The higher yields obtained in extractions carried out by high hydrostatic pressure and pulsed electric fields are of major interest from an industrial point of view, since solvent amounts were reduced and extraction times shortened. Thus, the combination of emerging technologies for extraction purposes and low-cost raw materials is an economical alternative to traditional extraction methods according to industry demands and a sustainable development.     

Combined densification and pulsed electric field treatment for selective polyphenols recovery from fermented grape pomace

The aim of this study is to assess a new process for the valorization of fermented grape pomace using pulsed electric fields (PEF). The combination of densification and PEF treatment was applied on grape pomace of low relative humidity, without any addition of conductive liquid. The kinetics of extraction and the composition of polyphenols were evaluated throughout the subsequent hydro-alcoholic extraction at different temperatures.Optimal parameters of PEF treatment (field strength E = 1.2 kV·cm^− 1; energy input W = 18 kJ·kg^− 1; density ρ = 1.0 g·cm^− 3) increased the content of total polyphenols regardless of the temperature of extraction. The ratio of total anthocyanins to total flavan-3-ols at 20 °C was equal to 7.1 and 9.0 for control and PEF treated modalities, respectively. These results demonstrate the selective nature of PEF treatment in anthocyanin extraction, and thus reveal new possibilities to produce extracts with different biochemical compositions.Industrial relevanceThis study examines the feasibility of densification combined with PEF pre-treatment of relatively low humidity grape pomace for the enhancement of bioactive compounds extraction. The concentration of total phenolic compounds obtained after PEF treatment showed that the use of this technique is relevant for an industrial use, since solvent amount and extraction time can be reduced. Moreover, the selective nature of PEF opens the opportunity to produce extracts of different biochemical compositions. This process is an alternative to conventional pre-treatments of raw material (e.g. dehydration and grinding), which have impacts on product quality and are more energy consuming.     

Enzyme-Assisted Production of Tomato Seed Oil Enriched with Lycopene from Tomato Pomace

Large amounts of a waste known as tomato pomace and consisting mainly of the fruit peel and seeds are generated annually from the industrial processing of tomatoes. This material is rich in lycopene, a phytochemical with antioxidant and chemopreventive properties, and contains many valuable nutrients. In this study, we have investigated the possibility of using the whole waste to produce a lycopene-enriched seed oil. The oil was obtained by cold-pressing the seeds and was subsequently enriched in lycopene (up to 500 ppm) by incorporation of a tomato oleoresin derived from the peels. To increase lycopene recovery, the peels were pretreated with cell-wall-degrading enzymes and solvent extracted. This procedure allowed the production of about 25 kg/ton oleoresin with an average lycopene content of 6.8 wt.%. The compositional characteristics of the oil combined with the production of significant amounts of oleoresin strongly support the use of tomato pomace for producing lycopene-based functional products.     

Comparison of the application of high pressure and pulsed electric fields technologies on the selective inactivation of endogenous enzymes in tomato products

Application of novel technologies such as high pressure (HP) or pulsed electric fields (PEF) on the remaining activity of endogenous tomato pectinolytic enzymes such as Pectinmethylesterase (PME) and Polygalacturonase (PG), responsible for tomato products texture was studied. HP combined with temperature (200–800 MPa @ 55–75 °C), PEF (5.5–12.5 kV/cm, 0–12 ms treatment time) and thermally treated (55–75 °C) samples were studied. After thermal treatment, PG appeared to be more resistant than PME. Opposite behavior was observed for HP treated samples. For PME inactivation more intense P-T process conditions were necessary compared to PG. For PEF treatment, 98% inactivation was observed at 12.5 kV/cm and 6 ms for PME, and at 5.5 kV/cm and 11 ms for PG. PME appeared to be more HP and PEF resistant compared to PG. The results support the potential application of HP and PEF to selectively inactivate PG while partially retaining PME in tomato juices, aiming in improved tomato products' textural characteristics.Industrial relevanceThe aim of the tomato industry is to produce tomato products of desired textural and sensorial characteristics while increasing the yield by decreasing the evaporated water. This can be achieved by applying novel technologies such as high pressure (HP) processing or pulsed electric fields (PEF) that affect the remaining activity of the endogenous pectinolytic enzymes such as Pectinmethylesterase (PME) and Polygalacturonase (PG), responsible for the final texture leading to products with improved quality characteristics such as viscosity, color and consistency. However, HP treatment is a batch process and makes it difficult for the treatment of large quantities (production of small quantities of superior products could be the target of the application of HP technology), while PEF technology could be applied in line with the typical production flow of that kind of products before the cold break step.     

The selected quality aspects of infrared-dried black soldier fly (Hermetia illucens) and yellow mealworm (Tenebrio molitor) larvae pre-treated by pulsed electric field

Drying is one of the most important steps in processing of edible insects biomass for their potential utilisation in food applications. In this study, the impact of pulsed electric field (PEF) pre-treatment (at E = 1.07 kV/cm and W_spec = 5 and 20 kJ/kg) on infrared-assisted air drying kinetics of black soldier fly (Hermetia illucens) and yellow mealworm (Tenebrio molitor) larvae has been evaluated. Moreover, microbial load and physical quality parameters of dried matter have been analyzed. The results show that PEF enhances the kinetics of water evaporation from insects biomass, especially in the range of the moisture ratio (MR) from 1.0 to 0.2. For instance, in the case of having been drying H. illucens larvae for 20 min, MR equalled 0.86, 0.75, and 0.72 for the untreated sample, 5 kJ/kg PEF-treated and 20 kJ/kg PEF-treated one, respectively. The effect of the PEF treatment was less visible in the case of H. illucens larvae and for low MR values. The PEF pre-treatment did not affect the water binding properties of dried insect biomass, regardless of species. However, the PEF pre-treated matter exhibited the same or even higher hygroscopic properties than the untreated ones. The difference in optical properties between untreated and PEF-treated samples was marginal. Nevertheless, for microbial contamination, 20 kJ/kg PEF treatment reduced the total number of microorganisms by 0.5–1.0 log cycle in comparison to the dried matter that had not been pre-treated. Nevertheless, the total number of microorganisms was too high to be feasible for food production purposes which would require additional operations to ensure food safety.Industrial relevanceThe interest in utilisation of insects as an alternative source of macronutrients for food and feed is growing tremendously. Drying is one of the most popular first steps in further processing technology applicable to insect biomass. Since air drying is one of the longest and the most energy consuming unit operation, there is a need to seek alternative methods that can be coupled with pre-treatment to enhance the process kinetics. In this paper, the combination of infrared drying of two species of insects preceded by pulsed electric field treatment has been discussed.     

溶液pH对番茄红素稳定性及其降解动力学研究

番茄红素易受溶剂环境的影响造成损失。为揭示溶液环境对番茄红素稳定性的影响规律,本文基于紫外可见吸收光谱的变化研究了二甲基亚砜、四氢呋喃、丙酮等不同溶剂种类、比例及酸碱度对番茄红素紫外可见吸收光谱及其吸收强度的影响,并进行降解动力学研究。结果显示:番茄红素在四氢呋喃和二甲基亚砜溶剂中的特征吸收波长与其在丙酮溶剂相比红移,吸收峰3的波长由505 nm分别红移至511 nm和523 nm;番茄红素在有机溶剂水溶液体系中均呈H型聚集,光谱表现为吸收波长蓝移;番茄红素在有机溶剂中的降解均符合一级反应动力学,其在丙酮水溶剂中的半衰期为25.48 h;番茄红素在弱酸和弱碱性条件下更稳定。结果表明:弱酸性或弱碱性的丙酮和四氢呋喃水溶液可作为番茄红素的良好溶剂,本研究为番茄类食品的储藏、加工及开发应用奠定理论基础。     

Bio-refinery of insects with Pulsed electric field pre-treatment

Insect production for food and feed purposes is rapidly emerging in Europe, in many cases relying on existing processing methods for blanching, freezing, drying, fractionating, but also seeking for more efficient and beneficial biomass treatment methods. Current study is aimed to explore the application of Pulsed electric fields (PEF) pretreatment of insect biomass (Hermetia illucens) for drying and oil extraction enhancement. The study demonstrates an increase in the drying rate of larvae pre-treated with PEF at 2 and 3 kV/cm; 5, 10 and 20 kJ/kg wet basis. No effect on fatty indices and amino acids profile were determined, but more free total amino acids especially at PEF with E = 2 kV/cm and 20 kJ/kg, were identified in press cake after pressing. Results from this study show, that PEF could be used as a pre-treatment before drying of insect mass to increase the drying rate or to decrease the drying time and the content of functional ingredients under gentle conditions. Slight increase in the oil yield after PEF treatment allows to propose this technique for oil extraction improvement.     

Natural Origin Lycopene and Its “Green” Downstream Processing

Lycopene is an abundant natural carotenoid pigment with several biological functions (well-known for its antioxidant properties) which is under intensive investigation in recent years. Lycopene chemistry, its natural distribution, bioavailability, biological significance, and toxicological effects are briefly outlined in the first part of this review. The second, major part, deals with various modern downstream processing techniques, which are assessed in order to identify promising approaches for the recovery of lycopene and of similar lipophilic compounds. Natural lycopene is synthesized in plants and by microorganisms, with main representatives of these two categories (for industrial production) tomato and its by-products and the fungus Blakeslea trispora, respectively. Currently, there is a great deal of effort to develop efficient downstream processing for large scale production of natural-origin lycopene, with trends strongly indicating the necessity for “green” and mild extraction conditions. In this review, emphasis is placed on final product safety and ecofriendly processing, which are expected to totally dominate in the field of natural-origin lycopene extraction and purification.     

Application of electrical treatments in alcoholic solvent for polyphenols extraction from grape seeds

The polyphenols extraction from grape seeds was studied. In order to increase the polyphenols yield and the extraction kinetics, three different pre-treatments were applied on grape seeds: pulsed electric fields (PEF) (8–20 kV/cm, 0–20 ms), high-voltage electrical discharges (HVED) (10 kA/40 kV, 1 ms) and grinding (180 W, 40 s). These electrical treatments can damage cell membranes (PEF/HVED) and cell walls (HVED) thus accelerating the compounds extraction but have different effects on the product fragmentation. The diffusion was then performed after pre-treatment with a mixture of water and ethanol. The PEF efficiency was improved when the treatment was performed at 50 °C in the presence of ethanol. PEF-assisted diffusion was then compared to HVED-assisted diffusion and to diffusion of ground grape seeds. These two pre-treatments increased both the extraction kinetics and the maximum polyphenols yield. For both cases, the final polyphenols content was 9 g GAE/100 g DM after 15 min of extraction with grinding and after 60 min with HVED. When PEF were applied in a suspension containing ethanol, the maximum polyphenols yield was also reached after 60 min. The subsequent solid–liquid separation was faster with PEF as compared to ground and HVED-treatments.     

Effect of pulsed electric field pre-treatment on the debittering process of cherry kernels

Cherry kernels occur in significant amounts as waste material during the processing of fruits. However, their subsequent use is limited due to the presence of cyanogenic glycosides, which are potentially dangerous to human health. In this study, the application of pulsed electric fields (PEF) was investigated as pre-treatment to improve the debittering process and to facilitate the degradation of cyanide precursors, naturally present in cherry kernels. Diverse PEF treatments were carried out at constant electric field strength of E = 2.2 kV/cm and specific energy input was varied between 10 and 50 kJ/kg, varying the number of pulses. Two different debittering procedures were performed with a common incubation time 0–20 h at 40 °C: a) incubation of whole kernels in deionized water; b) incubation of whole kernels without water stored in air at 80% relative humidity. HPLC analysis was used to examine the kinetics of the amygdalin and HCN contents. In both debittering methods, the PEF-treated samples with the highest intensity (2.2 kV/cm, 50 kJ/kg) showed higher and faster detoxification efficiency for the investigated compounds as compared to the untreated sample. In particular, the PEF treated samples incubated with water showed a reduction in the amygdalin and HCN contents of up to 86% (up to 72% of the raw material content.). Moreover, the PEF pre-treatment led to comparable efficiency in amygdalin reduction in both debittering processes: 86% reduction for the incubation with water and 81% for the incubation without water. Consequently, the combined application of PEF and the debittering process including incubation without water has remarkable potential as an industrial application due to its inherent reduced water consumption, and therefore, diminished wastewater management issues. A further advantage of this process is the minimizing of sugar loss typically occurring during the debittering through soaking.     

Pulsed Electric Field Assisted Extraction of Bioactive Compounds from Cocoa Bean Shell and Coffee Silverskin

The present study focused on the application of pulsed electric fields (PEF) as an innovative pre-treatment technique to improve the recovery of polyphenols from two food by-products, cocoa bean shell (CBS) and coffee silver skin (CS). The effect of the different operating parameters on the extraction of polyphenols was optimised using the response surface methodology statistical approach. The optimised methodology was compared with conventional extraction and applied to several CBS and CS samples to classify the samples according to origin, variety and industrial treatment. PEF-assisted extraction had higher (approximately 20%) recovery yields of polyphenols and methylxanthines than conventional extraction. Finally, the results highlighted that the composition of bioactive compounds from different extracts of CBS and CS and their antioxidant properties depended on the origin, variety and industrial processing of the raw material. These by-products may be a promising source of natural compounds, with potential applications on food and health sectors.     

High-humidity hot air impingement blanching (HHAIB): An emerging technology for tomato peeling

Peeling is an essential operation for tomato processing. A new peeling method, high-humidity hot air impingement blanching (HHAIB) heating technology, was developed as an alternative to the conventional lye and hot-water peeling to eliminate the use of chemicals and the discharge of wastewater. The current work explored the feasibility of HHAIB for tomato peeling. The effects of heating temperature (100–120 °C), relative humidity (20%–40%) and heating time (0–180 s) on the peeling performance were investigated. The optimum treatment was found to be 110 °C heating temperature in combination with 40% of relative humidity and 75 s treatment time, which resulted in lower peeling loss, firmness loss and color deterioration compared with other HHAIB conditions that achieved 100% peelability. The comparative study of optimized HHAIB peeling with conventional lye and hot-water peeling showed that HHAIB peeled tomato obtained lower peeling loss and firmness loss, and higher preservation of phytochemicals, antioxidant capacity and color. In addition, compared with fresh tomatoes, HHAIB processing increased the antioxidant activity, lycopene, and total phenolic content in peeled tomatoes by 16.01%, 10.46%, 12.80%, respectively. The laser scanning confocal microscopy image of fresh tomato skin surface and the scanning electron microscope images of peels and flesh showed that HHAIB caused cracking of the epidermis and melting of the cuticular membrane while reduced the serious damage of flesh.Industrial practicePeeling is a necessary step in tomato processing, which impacts subsequent processing efficiency and product quality. At present, the most common used peeling methods in the industry are hot water or/and alkali peeling, but it induces the loss of water-soluble nutrients, chemical residues and waste liquid treatment. Therefore, the industry urgently needs an alternative peeling technology. The current work shows that HHAIB is a very promising peeling technology as it not only has an excellent peeling performance, but also enhances the preservation of phytochemicals, antioxidant capacity and quality attributes compared to conventional lye and hot-water peeling.     

番茄深加工及其副产物利用研究现状

对国内外已报道的番茄皮、籽、残渣中有效成分的种类与特点,以及与之适应的综合加工利用技术进行归纳总结与对比分析,阐明了番茄加工副产物中番茄红素、膳食纤维、油脂、蛋白质等番茄副产物中主要营养成分的加工特性,以及不同方法与技术的适用性、特点及优缺点,提出了番茄加工副产物综合加工利用的问题与展望。     

Enhanced lycopene extraction from tomato industrial waste using microemulsion technique: Optimization of enzymatic and ultrasound pre-treatments

Microemulsion technique (MET) is a green scalable method allowing selective extraction of components of biological interest. This report deals with application of MET using natural surfactant, saponin, for lycopene extraction from industrial waste of tomato paste plants where the effects of ultrasound and enzyme treatments, surfactant:lycopene and surfactant:co-surfactant ratios as well as waste powder particle size on extraction efficiency were examined. Based on the results, a multi-step extraction scheme including ultrasound pre-treatment followed by enzymatic hydrolysis and then microemulsion extraction of tomato waste was led to an extended separation of the lycopene with minor surfactant use (mass ratio of saponin to lycopene 20:1). Under the optimized conditions, the efficiency showed an increase of just over 100% compared to initial experiment outcome. MET using saponin along with mild pre-treatments can be a simple, rapid, green and low-priced technique for lycopene extraction from tomato industrial waste and possibly other vegetable sources.Significance of the research data presented towards potential industrial applicationsSaponin is a renewable natural glycoside distributed in a wide variety of plants, low-priced to produce, stable over a wide range of pH values (from 2 to 11), already recognized as safe for use in foods and drinks by the FDA and therefore promising for its large scale industrial use in extracting applications as an appropriate alternative for synthetic surfactants. On the whole, simplicity and low energy requirements of the microemulsion technique as well as the low price of commercial saponin compared to biosurfactants and synthetic surfactants, make microemulsion technique a very promising technique to be scaled up.