Twin-screw extrusion technology for vegetable oil extraction: A review

Vegetable oils present a valuable class of bioresources with applications in both food and non-food industries and a production that has been steadily increasing over the past twenty years. Their extraction from oilseeds is a key process, as it exerts a strong impact on the resulting oil characteristics and quality. In view of the recent pressure towards sustainability, oilseed processing industries are taking renewed interest in thermomechanical pressing as a means to obtain high quality oils. This work focuses on twin-screw extrusion for vegetable oil extraction and reviews recent technological advancements and research challenges for the design and optimization of novel oil extraction processes. It comprises a critical analysis of the application of twin-screw extruders against their more conventional single-screw counterparts. Further, a comprehensive overview of the key parameters influencing the process performance is provided, while considerable attention is given to the development of innovative green extraction processes using twin-screw extrusion

Optimization of thermopressing conditions for the production of binderless boards from a coriander twin-screw extrusion cake

A deoiled press cake resulting from twin-screw extrusion of coriander fruits was used as a raw material for the production of self-bonded boards. The operating parameters for thermopressing were varied and include the applied pressure (19.6–39.2 MPa), molding time (60–300 s), and molding temperature (155–205 °C). The optimized process conditions (21.6 MPa, 300 s, 205 °C) resulted in a board with a density of 1323 kg/m3, a flexural strength of 23 MPa, a modulus of elasticity of 4.4 GPa, and a thickness swelling of 31%. The thickness swelling was effectively reduced to 20% through the application of a heat treatment at 200 °C after thermopressing. A variation of the moisture content of the press cake between 3 and 8% showed that increased moisture contents do not lead to improved mechanical properties of the resulting board and further induce internal fracturing of the board during thermopressing. The manufactured binderless boards may act as environmentally friendly alternatives to commercial wood-based boards such as oriented strand board and particleboard

Extraction of flavored coriander vegetable oil through extrusion technology

In an age where fossil resources are steadily depleting and environmental concerns have become an established subject of public and political discussions, the pursuit of sustainability is deeply entrenched in society. With regard to this and considering the consistently growing demand, the implementation of renewable resources in industrial processes could be a decisive solution. An interesting novel bioresource could be presented by Coriandrum sativum L., an annual herb from the family of Apiaceae and native to the eastern Mediterranean region. The coriander fruits are of particular interest, as they contain two distinct oil fractions. These comprise an essential oil with about 70% linalool and a vegetable oil, characterized by the presence of petroselinic acid, which constitutes over 70% of all fatty acids. Petroselinic acid, or cis-6-octadecenoic acid, presents a rare fatty acid common amongst the vegetable oils from Apiaceae crops. As a positional isomer of the more ubiquitous oleic acid, it may give rise to the synthesis of a series of novel, biobased compounds that could be of great interest to several industries. This renders the vegetable oil from coriander fruits particularly promising and as a consequence, the establishment of an efficient and economically favorable extraction process will constitute a major challenge for future research. Extrusion technology could present an attractive alternative to solvent extraction as it produces high quality vegetable oil that has not come into contact with any chemical substances. Further, the press cakes may find various profitable applications due to their essential oil content and antioxidant activity. Next to this, the extrusion cakes constitute natural biocomposites and could be transformed to value-added agromaterials through thermopressing. These biodegradable polymers could possibly replace less sustainable materials in automobile, building and furniture industries. The major disadvantage of mechanical pressing is considered its relatively low extraction yields and consequently a high residual oil content within the press cakes. A possible solution may lie within the application of seed pretreatments prior to the extrusion process. Therefore, the moisture content of coriander fruits was varied and the effect on the crushing behavior and extraction efficiency through single-screw, as well as twin-screw extrusion was assessed

In situ product recovery of bio-based industrial platform chemicals : a guideline to solvent selection

In situ product recovery (ISPR), in the form of an extractive fermentation process, can increase productivity and product titers in the sustainable production of platform chemicals. To establish a guideline for the development of industrially relevant production processes for such bio-based compounds, a wide screening was performed, mapping the potential of an extensive range of solvents and solvent mixtures. Besides solvent biocompatibility with Saccharomyces cerevisiae, distribution coefficients of three organic acids (protocatechuic acid, adipic acid and para-aminobenzoic acid) and four fragrance compounds (2-phenylethanol, geraniol, trans-cinnamaldehyde and β-ionone) were determined. While for highly hydrophobic fragrance compounds, multiple pure solvents were identified that were able to extract more than 98%, reactive extraction mixtures were proven effective for more challenging compounds including organic acids and hydrophilic alcohols. For example, a reactive mixture consisting of 12.5% of the extractant CYTOP 503 in canola oil was found to be biocompatible and showed superior extraction efficiency for the challenging compounds as compared to any biocompatible single solvent. This mapping of biocompatible solvents and solvent mixtures for the extraction of various classes of industrial platform chemicals can be a tremendous step forward in the development of extractive fermentations

Extraction of Coriander Oil Using Twin‑Screw Extrusion: Feasibility Study and Potential Press Cake Applications

This study presents an assessment of the vegetable oil extraction from coriander fruits through mechanical pressing, more specifically twin-screw extrusion. This comprises an evaluation of the oil recovery obtained and its respective quality, as well as the specific mechanical energy, representing an economical point of view. With regard to the extrusion optimization, the screw configuration, the device’s filling coefficient and the pressing temperature were varied. The screw configuration was shown to exhibit a key influence on the extraction efficiency and oil recoveries of at least 40 % were reached when the pressing zone was positioned immediately after the filter and consisted of 50 mm long, reverse screws with a -33 mm pitch. Furthermore, with a device’s filling coefficient of 39.4 g/h rpm and a pressing temperature of 120 °C, an oil recovery of 47 %, the highest of this study, was reached with concurrent low energy consumption. Next to this, operating parameters of 47.1 g/h rpm and 80 °C resulted in the production of a press cake with the lowest residual oil content (15 %) in this study, although this also involved a significant increase in the filtrate’s foot content. All the produced oils were of acceptable quality (<1.5 % acidity), showed high petroselinic acid content (73 %), and were pleasantly scented

Petroselinic acid purification and its use for the fermentation of new sophorolipids

Petroselinic acid, a positional isomer of oleic acid, was isolated from the vegetable oil of Coriandrum sativum fruits. This uncommon fatty acid was subsequently used as substrate for sophorolipid fermentation with a Starmerella bombicola lactone esterase overexpression (oe sble) strain. A petroselinic acid based diacetylated sophorolipid lactone was obtained in high purity without incorporation of de novo synthesized fatty acids such as oleic acid. A total production of 40 g/L was obtained. The petroselinic acid based sophorolipid lactone was subsequently hydrolyzed towards the petroselinic acid based sophorolipid acid. For both compounds, their critical micelle concentration (CMC) and corresponding surface tension were compared to their oleic acid based counterparts. Both petroselinic acid based sophorolipids displayed a much lower CMC value than their oleic acid based counterparts, although their minimal surface tension was the same. Besides, the sophorolipid fermentation product was chemically modified towards a novel C12 sophorolipid aldehyde. This derivative constitutes an interesting building block for further modification towards new-to-nature sophorolipids with high potential for self-assembly applications

Biorefinery of coriander seeds cultivated in France

Coriander (Coriandrum sativum L.) is an annual crop belonging to the Apiaceae family and is commonly used as a condiment or a spice in the Mediterranean area. The seeds are characterized by their potential to provide both an essential and a vegetable oil. While the former fraction is traditionally obtained through hydrodistillation, the latter may be extracted by twin-screw extrusion. This further renders a press cake which could be valorized through its transformation into agromaterials. The main objectives of this study were to determine the chemical composition of hydrodistilled essential oil from coriander seeds cultivated in France and to evaluate VOC emission rates from two types of agromaterials generated from delipidated or non-delipidated coriander cake. The main components of the essential oil were linalool, g-terpinene, camphor and limonene. Enantiomeric distribution of linalool showed an enantiomeric excess of (S)-linalool (75.2%). VOC emissions of agromaterials were mainly due to the presence of essential oil in the press cake. Linalool was the most abundant compound with an emission rate of about 140 μg/m² h for the non-delipidated material. This value was lower than 2 μg/m² h for the delipidated material. Next to this, a substantial emission of the solvent used for lipid extraction was detected

Characterization of french coriander oil as source of petroselinic acid

Coriander vegetable oil was extracted from fruits of French origin in a 23% yield. The oil was of good quality, with a low amount of free fatty acids (1.8%) and a concurrently high amount of triacylglycerols (98%). It is a rich source of petroselinic acid (C18:1n-12), an important renewable building block, making up 73% of all fatty acids, with also significant amounts of linoleic acid (14%), oleic acid (6%), and palmitic acid (3%). The oil was characterized by a high unsaponifiable fraction, comprising a substantial amount of phytosterols (6.70 g/kg). The main sterol markers were β-sitosterol (35% of total sterols), stigmasterol (24%), and Δ7-stigmastenol (18%). Squalene was detected at an amount of 0.2 g/kg. A considerable amount of tocols were identified (500 mg/kg) and consisted mainly of tocotrienols, with γ-tocotrienol as the major compound. The phospholipid content was low at 0.3%, of which the main phospholipid classes were phosphatidic acid (33%), phosphatidylcholine (25%), phosphatidylinositol (17%), and phosphatidylethanolamine (17%). About 50% of all phospholipids were non-hydratable. The β-carotene content was low at 10 mg/kg, while a significant amount of chlorophyll was detected at about 11 mg/kg. An iron content of 1.4 mg/kg was determined through element analysis of the vegetable oil. The influence of fruit origin on the vegetable oil composition was shown to be very important, particularly in terms of the phospholipids, sterols, and tocols composition21

The coriander straw, an original agricultural by-product for the production of building insulation materials

Straw represents 60-80% of the aerial part of coriander. It is cheap (90 €/ton including harvesting, bunching and transportation) and has an availability of 250 tons/year. However, the latter will grow strongly in the next five years due to the increasing use of vegetable oil from the fruits for food, cosmetics or the chemical industry. Due to its high lignocellulose content (62%), coriander straw is an interesting crop by-product for the production of bio-based building materials. Two types of insulating materials are presented here. Firstly, it is possible to produce bulk materials by thermo-mechano-chemical refining of straw with water using a twin-screw reactor. According to the applied liquid/solid ratio (0.4-1.0), it is possible to control the fiber aspect ratio of the refined straw (22.9-26.5) and thus the tapped density of the resulting bulk material (110-61 kg/m3). For the lowest density, the thermal conductivity was 47.3 mW/m K, corresponding to a 1.06 m2 K/W resistance for a 5 cm thickness of extrusion-refined straw. Twin-screw refining was also successfully conducted with an aqueous borax solution, allowing fire-proofing of the straw. When used as loose fill in housing, refined coriander straw is a promising solution for building insulation. Medium-density insulation blocks can also be manufactured using compression molding by combining coriander straw (milled or extrusion-refined) and a starch-based binder. The use of a milled straw (7.5 mm sieve) mixed with 15% binder, cold pressed (87 kPa, 30 s) and then dried, resulted in cohesive blocks with a 155 kg/m3 density and a 55.6 mW/m K thermal conductivity, corresponding to a 0.90 m2 K/W resistance for a 5 cm thickness. Similarly, such blocks could be used for the thermal insulation of buildings, including the filling of walls, interior partitions, etc

Impact of thermomechanical fiber pre-treatment using twin-screw extrusion on the production and properties of renewable binderless coriander fiberboards

The aim of this study consisted of manufacturing renewable binderless fiberboards from coriander straw and a deoiled coriander press cake, thus at the same time ensuring the valorization of crop residues and process by-products. The press cake acted as a natural binder inside the boards owing to the thermoplastic behavior of its protein fraction during thermopressing. The influence of different fiber-refining methods was evaluated and it was shown that a twin-screw extrusion treatment effectively improved fiber morphology and resulted in fiberboards with enhanced performance as compared to a conventional grinding process. The best fiberboard was produced with extrusion-refined straw using a 0.4 liquid/solid (L/S) ratio and with 40% press cake addition. The water sensitivity of the boards was effectively reduced by 63% through the addition of an extrusion raw material premixing operation and thermal treatment of the panels at 200 °C, resulting in materials with good performance showing a flexural strength of 29 MPa and a thickness swelling of 24%. Produced without the use of any chemical adhesives, these fiberboards could thus present viable, sustainable alternatives for current commercial wood-based materials such as oriented strand board, particleboard and medium-density fiberboard, with high cost-effectiveness