Volume 2 Special Issue 1 2008
How to reference: Arce A, Soto A (2008) Citrus Essential Oils: Extraction and Deterpenation. In: Benkeblia N, Tennant P (Eds) Citrus I. Tree and Forestry Science and Biotechnology 2 (Special Issue 1), 1-9
Noureddine Benkeblia, Paula Tennant
University of the West Indies, Jamaica
CONTENTS AND ABSTRACTS
Alberto Arce, Ana Soto (Spain) Citrus Essential Oils: Extraction and Deterpenation (pp 1-9)
Invited Mini-Review: The essential oils of citrus fruits are valuable raw materials in the scent and flavouring industries. As extracted, they are complex mixtures with large proportions of terpene hydrocarbons that make them easily oxidizable and insoluble in aqueous and alcoholic solutions. This mini-review surveys the main processes by which these essential oils are currently extracted and deterpenated, and also the current state of research into their deterpenation by means of ionic liquids.
Leandro Danielski (Germany), Sandra R. S. Ferreira, Haiko Hense, Julian Martínez (Brazil), Gerd Brunner (Germany) Deterpenation of Citrus Peel Oils with Supercritical Carbon Dioxide – A Review (pp 10-22)
Invited Review: Citrus oils are used worldwide as raw materials for the food, flavor, cosmetic, pharmaceutical and chemical industries. Basically, citrus oils are a mixture of oxygenated, high-volatile and low-volatile compounds. The high-volatile fraction is mostly composed of terpenes, whereas the most important contribution to the oil’s distinct flavor and fragrance comes from oxygenated compounds. Since terpenes can degrade and produce undesirable off-flavors, they must be removed in order to stabilize the final product by a process called deterpenation. Traditionally, the removal of terpenes is by distillation. In order to avoid the drawbacks presented by the conventional processes, including high operational temperatures, supercritical extraction techniques have been extensively investigated in the last few decades. This present review focuses on the deterpenation of citrus peel oils using supercritical carbon dioxide (SC-CO2) as solvent. To date, two different deterpenation techniques employing SC-CO2 have gained relevance: supercritical ad-/desorption and countercurrent multistage fractionation. An overview of these processes is presented. In general, both processes have shown the capacity of concentrating oxygenated compounds from citrus oils at relatively mild temperatures (not higher than 70°C). Deterpenation in a countercurrent column has proved to be more suitable for obtaining folded extracts, whereas supercritical ad-/desorption are more appropriate when higher purification is required.
Berta Alquézar, María Jesús Rodrigo, Lorenzo Zacarías (Spain) Carotenoid Biosynthesis and their Regulation in Citrus Fruits (pp 23-35)
Invited Review: Carotenoids are the main pigments responsible for the attractive color of the peel and pulp of citrus fruits and greatly contribute to their nutritional and antioxidant value. Fruits of different Citrus species display a broad array of color singularities and in many cultivars the peel and the pulp also exhibit different color, envisaging specie- and tissue- specific regulation of the carotenoid content and composition. In addition, citrus mutants affected in fruit color are a useful experimental system to identify molecular mechanisms regulating carotenoid biosynthesis. Citrus is, therefore, an excellent model to study fruit carotenoid accumulation and their regulation. In this review, we summarize and update information on carotenoid content and composition in fruits of agronomically important Citrus species. Current understanding of carotenoids biosynthesis in citrus, highlighting the main regulatory steps of the pathway and how may be related to carotenoid content and complement in peel and pulp of Citrus fruits are discussed. Finally, the effect of environmental and endogenous factors on citrus fruits carotenoids is also evaluated.
Shiming Li (USA), Min-Hsiung Pan (Taiwan), Zhenyu Wang, Ted Lambros, Chi-Tang Ho (USA) Biological Activity, Metabolism and Separation of Polymethoxyflavonoids from Citrus Peels (pp 36-51)
Invited Review: Polymethoxyflavonoids (PMFs) almost exclusively exist in citrus plants. In recent years, there has been increasing and particular interests in the exploration of the health benefits associated with PMFs. PMFs are reported to exhibit a broad spectrum of biological activities, such as anti-inflammatory, anti-carcinogenic, anti-tumor, anti-viral, anti-thrombogenic and anti-atherogenic properties. Metabolic studies, especially the identification of in vivo biotransformation products of PMFs, have revealed that the major metabolites are desmethylated or hydroxylated PMFs. Biological screening of some of these metabolites has revealed that they may possess more potent bioactivities such as anti-inflammatory and anti-cancer properties. Elucidation and biological activity study of PMF metabolites may lead to further exploration and understanding of PMFs’ health benefits and the mechanism along with the beneficial properties in human beings. The increased demand of PMFs for efficacy and clinical trial studies has resulted in a demanding supply for pure PMFs in large quantities. Consequently, separation and characterization of PMFs have attracted increasing attention and new techniques have evolved dramatically in recent studies. However, the development of an efficient large-scale separation method(s) as well as robust and reliable analysis method(s) for PMFs and their metabolites are needed and eventually will be developed in the near future because of the significance and urgency. This review describes the occurrence, bioactivity, bioavailability, metabolism and chemistry of PMFs from citrus genus, especially the peels of citrus fruits.
María Teresa Pretel, Paloma Sanchez-Bel, Isabel Egea, Félix Romojaro (Spain) Enzymatic Peeling of Citrus Fruits. Factors Affecting Degradation of the Albedo (pp 52-59)
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Invited Mini-Review: The environmental problems caused by chemical peeling of citrus, together with the establishment of new applications for enzymatic preparations with degradative activities led several investigators to study enzymatic peeling as an alternative to traditional chemical peeling. The principle of enzymatic peeling is based on the digestion, through an enzymatic preparation, of the pectic substances existing in the cell wall of plants. The efficiency rate of enzymatic peeling is influenced by the morphological characteristics of citrus fruits, the correct vacuum application and the incubation time, as well as by the type and concentration of enzymatic solution, and temperature, among others. For the enzymatic peeling of citrus, it is important to take into account the ripening stage of the fruits, since variations this parameter modify the concentrations of enzymatic preparation necessary for the peeling process and, probably, the optimum conditions of vacuum. Optimum conditions for enzymatic peeling may not depend on the composition of the albedo in different citrus species. A temperature range between 35 and 40°C, besides being within the optimum range of peeling, would become economically profitable for the industry since a minimum addition of energy is required. For enzymatic peeling the pH range could be wider, between 3.5 and 4.5. The optimum concentration for obtaining a quality product with Peelzym® II is 1 ml L-1, but depends on the composition of the enzymatic solution. The aim of this paper is to update information about the most important parameters implied in enzymatic peeling of citrus fruits, especially factors affecting degradation of the albedo.
Abrisham Tanhatan Nasseri (Iran), Jean-François Thibault, Marie-Christine Ralet (France) Citrus Pectin: Structure and Application in Acid Dairy Drinks (pp 60-70)
Invited Review: Pectin, a plant cell wall polysaccharide, is mainly used in food industries for its gelling and stabilizing properties. In industrial applications, pectin is usually widely extracted from citrus peels, and in some intances, apple pomace is also used. Lime and lemon are the preferred citrus species used in the extraction of pectin, while orange and grapefruit are used less often. In the food industry, pectin is widely employed in the production of jams and jellies, confectionary products and bakery fillings. The fine structure of pectin is affected by many parameters, such as the origin of raw material and extraction conditions. This structural variability impacts greatly on pectin functional properties. The other major use of pectin concerns the stabilization of acidified milk drinks and yogurts. With their refreshing natural taste and high nutritional value, acidified milk drinks enjoy great popularity. A large selection of different sour milk drinks, which vary according to the manufacturing process, ingredients and consistency, is available to meet the needs of every consumer. In all cases, protein flocculation and whey separation occur in the absence of stabilizers in acidified milk drinks. To prevent this behaviour and to stabilize milk drinks, citrus pectin can be added as a protecting colloid. This review presents the structure of citrus pectin and functionality, with a special emphasis on acid dairy drinks.
Ron Porat (Israel) Degreening of Citrus Fruit (pp 71-76)
Invited Mini-Review: The practice of postharvest degreening of green but otherwise mature and edible citrus fruit has developed in order to promote external color development, i.e., destruction of the green chlorophyll pigments and accumulation of orange/yellow carotenoid pigments. The degreening process is complicated, since it depends on various endogenous and exogenous factors, such as fruit maturity at harvest and sensitivity of the fruit to ethylene, and is influenced by ethylene concentrations and the duration of the degreening process, the temperature and relative humidity used, efficacy of air circulation and ventilation, etc. Although the commercial beneficial effect of ethylene on color development is well known, packers and exporters must be aware of the detrimental effects of ethylene, and pay special attention to its effects of enhancing decay development and stimulating senescence, which result in the appearance of various peel disorders. Overall, for efficient degreening, it is recommended to harvest the fruit at the onset of natural color development or later, and to use the lowest ethylene concentration and shortest exposure time possible. In addition, it is proposed to degreen the fruit under moderate temperatures of 20-25°C and high humidity of 95% RH, and to be sure to have appropriate air circulation and ventilation. Further details and recommendations regarding minimizing of decay development and appearance of peel disorders are discussed.
José A. Cayuela Sánchez (Spain) Citrus Internal Quality Predictions by NIR Spectroscopy (pp 77-82)
Invited Mini-Review: Consumer perception and satisfaction regarding fruit quality is an important issue in marketing. However, there is a lack of objective information that will allow consumers to choose fruit of a desired quality. Good correlations, well established in the literature, exist between soluble solid content and consumer acceptance of several fruit. Commercial application of near infrared spectroscopy (NIR) to fruit sorting by soluble solids was first initiated in Japan in 1990, and this technology has been applied to pack-house fruit sorting lines for sweetness of citrus, apples, pears and peaches, since the mid 1990s in Japan, and more recently in other countries. At present, NIR technology applied to nondestructive measurement of fruit quality is in development. Commercially available instruments for these applications are few and scientific evaluation of calibration models for the measurement of the most important fruit internal quality parameters is needed. NIR technology has the potential to become a suitable instrument, not only to sorting citrus fruit by some quality parameters but also to develop ‘electronic tasters’ based on the correlation among NIR measuring and sensory analysis. As well, the direct use of portable instruments by consumers for purchasing decision, could become of interest. A brief review is done in this work on the state of the art of NIR applied to citrus quality prediction.
Diomi Mamma, Paul Christakopoulos (Greece) Citrus Peels: An Excellent Raw Material for the Bioconversion into Value-added Products (pp 83-97)
Invited Review: Citrus by-products are the processing wastes generated after citrus juice extraction and constitute about 50% of fresh fruit weight. This solid residue is comprised of the peel (flavedo and albedo), pulp (juice sac residue), rag (membranes and cores) and seeds. The disposal of fresh peels is becoming a major problem for many factories. Usually, citrus juice industries dry the residue and it is either sold as raw material for pectin extraction or pelletized for animal feeding, though none of these processes is very profitable. This residual material is a poor animal feed supplement because of its extremely low protein content and high amount of sugar. The application of agroindustrial by-products in bioprocesses offers a wide range of alternative substrates, thus helping to solve pollution problems related to their disposal. Attempts have been made to use citrus by-products to generate several value-added products, such as enzymes, single cell protein, natural antioxidants, ethanol, organic acids, polysaccharides and prebiotics. This article reviews developments regarding processes and products that have employed citrus peels as a substrate for biotechnological applications.
Pantelis E. Zoiopoulos, Manousos Volanis, Pantelis I. Natskoulis (Greece) Investigation into the Use of Citrus By-Products as Animal Feeds in Greece (pp 98-101)
Invited Mini-Review: Citrus, orange in particular, is an important crop grown in Greece. Part of the fruit yield is used for making juice in canning industry, leaving citrus pulp as the main by-product. On the other hand sheep keeping is the main animal production activity in the area. Therefore the utilisation of citrus industry by-products as animal feeds for this sector suggests itself. Attempts have been made over the years in Greece to study the nutritive value of various types of citrus by-products as feeds for sheep. Firstly, a citrus canning industry by-product, namely Dried Citrus Pulp, has been studied in sheep nutrition. In addition, ensiling of fresh citrus pulp has been tried and characteristics of fermentation have been recorded. Ensiled Citrus Pulp was fed to small ruminants and performance of lactating animals, as well as, quantitative and qualitative traits of milk were assessed. Furthermore, the use of Ensiled Surplus Oranges was studied with lactating dairy sheep. Finally, the biotechnological upgrading of citrus pulp, protein enrichment in particular has been also attempted. Some sensible results emerged from these studies, among them, that ewes fed ensiled citrus feed tended to have higher fat content in milk. Results show that the inclusion of citrus by-products in diets of lactating sheep is a viable proposition, particularly for the dairy breed of sheep whose milk is used for cheese manufacturing industry in countries round the Mediterranean basin but also elsewhere.
Siok-Lam Lim (USA/Singapore), Theresa May-Chin Tan (Singapore), Lee-Yong Lim (Australia) Effects of Citrus Fruit Juices on P-glycoprotein-mediated Transport in L-MDR1 Cells and CYP3A4-mediated Metabolism in Human Intestinal Microsomes (pp 102-111)
Original Research Paper: Fruit juice-drug interactions involving drug transporters and metabolic enzymes have been studied with various citrus fruit juices. The collective data led us to hypothesize that the modulating activity of citrus fruit juices on cellular transport and metabolic pathways is dependent on the dominant flavonoid pattern and taxonomy of the citrus fruits. This hypothesis has important implications given the difficult task of compiling complete constituent profiles for fruit juice, and the limited success in identifying the active modulating component(s) in the juice. Grapefruit and pummelo are classified under the neohesperidosyl species based on a dominant flavonoid pattern, while lime and lemon belong to the rutinosyl species. Classification of these fruits based on taxonomy yielded parallel groupings. Orange belongs to the same taxonomic family as grapefruit and pummelo, but is classified as a rutinosyl species, with lime and lemon, based on a dominant flavonoid pattern. In the present study, the citrus fruit juices were found to modulate bi-directional digoxin transport across the MDR1-transfected L-MDR1 cells in a manner consistent with the proposed hypothesis. Orange juice, like grapefruit and pummelo juices, inhibited P-gp-mediated transport of digoxin by 60-70% when applied at 50% concentration. Lime and lemon juices, however, did not modulate the digoxin transport profile characteristically of a P-gp inhibitor. Data for orange juice thus suggested that taxonomy, rather than dominant flavonoid pattern, had a greater influence on its capacity to modulate cellular permeation. The hypothesis could not, however, be applied to predict the effects of the citrus fruit juices on P-glycoprotein expression in the L-MDR1 cells. Neither could it be applied to the effects of the fruit juices on cytochrome P450 3A4-mediated metabolism of midazolam, which appeared to be predominantly influenced by the furanocoumarins content of the juices.
Siok-Lam Lim (USA/Singapore), Lee-Yong Lim (Australia) Effects of Citrus Fruit Juices on Organic Cation Transporter 2 Function and Expression in Vitro (pp 112-120)
Original Research Paper: Organic cation transporter 2 (OCT2) plays an important role in the renal clearance of endogenous and exogenous organic cations, including drugs and their metabolites. Citrus fruit juice interactions with the P-gp efflux transporter are well-established, but there is to date no study on the effects of citrus fruit juice on OCT2 function and expression. This paper evaluates the modulating activities of grapefruit, pummelo, orange, lime and lemon juices on porcine OCT2 (pOCT2) in LLC-PK1 cells. pOCT2-mediated transport of rhodamine-123 (R-123) across confluent LLC-PK1 cell monolayers in the apical-to-basal direction was confirmed by transport and uptake data in the presence of tetraethylammonium (TEA) and verapamil (OCT2 and P-gp inhibitors, respectively). Grapefruit juice at 10%, and pummelo and orange juices at 10 to 30%, produced R-123 transport and cellular accumulation profiles consistent with the OCT2-inhibitory effects of TEA. Cellular pOCT2 expression was up-regulated by pummelo, orange and lime juices at 5, 30 and 10%, respectively. The effect of lime juice on pOCT2 transport activity could not be verified due to its overriding influence on the paracellular transport pathway, while lemon juice at 10 to 30% did not appear to affect the function and expression of the pOCT2 transporter. Given that grapefruit, pummelo and orange share the same taxonomic classification, it may well be that common components in these citrus fruit juices are potent modulators of the function and/or expression of the OCT2 transporter.
André Costa Gargano, Celso A. R. Almeida Costa, Mirtes Costa (Brazil) Essential Oils from Citrus latifolia and Citrus reticulata Reduce Anxiety and Prolong Ether Sleeping Time in Mice (pp 121-124)
Original Research Paper: Essential oils (EO) from Citrus reticulata and Citrus latifolia were submitted to classical experimental procedures, such as light-dark box and marble-burying tests with male Swiss mice, to evaluate anxiolytic activity. Sedative activity was also investigated with EO from C. aurantium using the sleeping time induced by ether inhalation. EOs were administered 30 min before the experiments in doses ranging from 0.5 to 2.0 g/kg (w/v). EO from C. latifolia showed a positive effect on light-dark box parameters, and those from both C. reticulata and C. latifolia were able to reduce the number of buried marbles. Positive results were obtained using experimental procedures related to generalized anxiety (light-dark box) and obsessive-compulsive disorders (marble-burying), suggesting some differences in the spectrum of anxiolytic activity. EO from all citrus species significantly increased the duration of sleep induced by ether inhalation, disregarding the potential interaction with hepatic enzymes, which is a limitation of barbiturate sleeping time. On the other hand, this effect was detected only with higher doses, emphasizing that specificity of this action should be investigated. Results obtained with EOs from C. reticulata and C. latifolia confirm the central nervous system activity previously described for C. aurantium. Further investigation is warranted to guarantee the safe use of EOs by the population.
Lorenzo Camarda, Vita Di Stefano, Rosa Pitonzo, Domenico Schillaci (Italy) In Vitro Antiproliferative Properties and Flavanone Profiles of Six Grapefruit (Citrus paradisi Macf.) Cultivars (pp 125-127)
Short Communication: Recent studies suggest an inverse relationship between the intake of Citrus fruits and the incidence of cardiovascular diseases, stroke and different cancer types. Protective effects shown could be ascribed to the flavonoid content of Citrus fruits. A reversed-phase high-performance liquid chromatographic method was developed to determine the content of flavanone glycosides, which are the main flavonoids present in Citrus fruits. Fresh squeezed juices of six different grapefruit cultivars (Citrus paradisi Macf.) were analysed. In all grapefruit juices tested, we found total flavanone glycoside contents in the range from 33.93 to 44.97 mg/100 ml of juice; naringin was the main flavanone component (16.37-26.14 mg/100 ml of juice). To evaluate pharmacological activity and, in particular, inhibitory effects in vitro on proliferation and growth of cancer cells, the six freshly squeezed grapefruit juices were tested against K562 (human chronic myelogenous leukemia), NCI-H460 (human lung cancer) and MCF-7 (human breast adenocarcinoma) cell lines. Most of the tested grapefruit juices showed distinct antiproliferative activity against all three cancer cell lines; in particular ‘Ruby Red’ and ‘Foster’ grapefruit juices showed the best activity in inhibiting the growth of NCI-H460 and MCF-7 cell lines at 3% v/v (fresh juice volume diluted in cell culture medium).
Maria J. Esteve, Ana Frigola (Spain) The Effects of Thermal and Non-thermal Processing on Vitamin C, Carotenoids, Phenolic Compounds and Total Antioxidant Capacity in Orange Juice (pp 128-134)
Original Research Paper: The abundance of fresh drinks based on fruit juices, especially citrus juices, and minimally processed products allow consumers to ingest a wide variety of antioxidants in the diet, such as vitamin C, carotenoids, flavonoids and other phenolic compounds. Pulsed electric fields (PEF) and high hydrostatic pressure (HHP) are emerging technologies in the field of food preservation. They have the potential to pasteurize various foods non-thermally, and it has been verified that these new technologies guarantee the safety (death of microorganisms) and stability (PME) of juices, with less quality loss in the final product. The effect of non-thermal processing (PEF, HHP) and pasteurization on total phenolic compounds, total antioxidant activity, vitamin C and carotenoids of orange juice was studied. There was a statistically significant reduction (p<0.05) in Trolox equivalent antioxidant capacity (TEAC) when juice was processed by either of these treatments, but the decrease was higher after pasteurization. TEAC decreased during refrigerated storage (4°C) of the samples analysed. Vitamin C concentration did not change significantly after pasteurization and non-thermal treatment; during refrigerated storage. However, vitamin C decreased more in pasteurized juice than in juice treated by PEF and HHP. The vitamin A concentration in the refrigerated orange juice was affected less by non-thermal treatments than by conventional thermal treatments. Total phenolic compounds were always higher in the untreated orange juice, followed by juice treated by PEF and HHP and finally by pasteurized juice, although the differences were not statistically significant (p>0.05), and during refrigerated storage they remained practically constant in all samples. Furthermore, a juice with similar characteristics as fresh juice, while preserving the bioactive compounds which provide it with its wealthy properties, is obtained.
Diomi Mamma, Paul Christakopoulos (Greece) Citrus Peels: A Potential Feedstock for Bioethanol Production (pp 135-140)
Original Research Paper: Orange peels (OPs) and water unextractable orange peels (WUOPs) were evaluated as feedstocks for bioethanol production, applying simultaneous saccharification and co-fermentation (SSCF). Τhe fungi, Fusarium oxysporum F3 and Neurospora crassa DSM 1129, were grown aerobically under solid state cultivation (SSC) in order to produce the necessary enzymes for hydrolyzing the polysaccharides present in OPs. Following aerated growth and production of hydrolytic enzymes, OPs and WUOPs were fermented to bioethanol. Factors affecting bioethanol production such as, OP and WUOP concentration and the use of single fungal or mixed culture with S. cerevisiae, were investigated. Both microorganisms were capable of producing bioethanol in single or mixed cultures with S. cerevisiae. F. oxysporum F3 was a better ethanol producer than N. crassa in single or mixed cultures. Yields as high as 23 g of ethanol/100 g of added OPs and 19.98 g of ethanol/100 g of added WUOPs corresponding to 65% and 74%, respectively, of the theoretical yield based on total carbohydrate content of OPs or WUOPs, were achieved with F. oxysporum F3.