Pure Olive Oil Research Articles

Prepared of Olive Oil Doped SiO<sub>2</sub> via Sol-Gel Technique

Olive oil doped Nanosilica is successfully prepared by wet chemical synthesis method. Samples were analyzed by a variety of techniques, including X-ray diffraction, FTIR, absorption and emission spectrometers to report the capability of Sol-Gel technology on preparing of silica monolith as a host material for Olive oil, and investigate the effect of converting Olive oil to a solid state on its optical properties. Some absorption bands of Olive oil are disappearing from absorption spectrum of doped silica. Only single strong fluorescence peak was appearing in fluorescence spectrum of pure Olive oil at wavelength around 678 nm which attributed to chlorophylls, while fluorescence spectrum to doped sample shows two strong fluorescence peaks at the wavelength 681 nm and 585 nm which attributed to chlorophylls and Vitamin E respectively. The doping process enhances fluorescence activity of Olive oil through enhancing intensity of the fluorescence peak corresponding to Vitamin E. Absorption and fluorescence spectrums to doped silica sample give a good indication in direction of using Sol-Gel technique to prepare for Olive oil doped SiO2 as an optical active material.

Applied Study of Pattern Recognition and Near Infrared Spectroscopy

According to the status of lacking fast detection technology to adulteration olive oil, the paper presented a new method based on near infrared spectroscopy technology and pattern recognition. 10 samples of pure olive oil were collected. 2 kinds of adulteration samples were respectively made up with soybean oil and rapeseed oil. The Identification models were build respectively by support vector machines and hierarchial clustering. The result showed that the model’s performance built by SVM was better than the model by hierarchial clustering. The recognition ratio and prediction ratio of SVM were 100%.The experiments shown that the fast detection technology based on NIR and pattern recognition had better feasibility and practicability in identifying adulteration olive oil.

Isomerisation of carrot β-carotene in presence of oil during thermal and combined thermal/high pressure processing

The effect of thermal processing (85–130°C) and combined thermal/high pressure processing (100°C combined with 0.1 to 700MPa and 700MPa combined with 85–115°C) on β-carotene isomerisation in an olive oil/carrot emulsion and pure olive oil phase enriched with carrot β-carotene was investigated. Thermal processing always resulted in an increase in the contribution of the cis-isomers, with the increase being more pronounced at higher temperatures. In the oil/carrot emulsion, less β-carotene isomerisation was observed during combined thermal/high pressure processing compared to thermal processing. This effect was attributed to strengthening of the carrot cell walls under high pressure, thereby hindering the transfer of β-carotene to the oil phase and lowering its susceptibility to isomerisation. In an oil phase enriched with β-carotene, β-carotene isomerisation was not influenced by the applied pressure at 100°C and became almost temperature insensitive at 700MPa.

Development of an indirect method of microalgal lipid quantification using a lysochrome dye, Nile red

Earlier studies showed that the lipophilic dye, Nile red (9-diethylamino 5H-benzo[α]phenoxazine-5-one) can be used to measure the lipid content of microalgae by cellular in vivo fluorescence. It was observed that a higher amount of lipid present in lipid droplets of microalgal cells would result in higher degree of emitted fluorescent light. In this present study, the feasibility of using Nile red, a fluorescent dye specific for intracellular lipid droplets, as an indirect method of lipid quantifications was investigated. Following cellular staining of different microalgal species with nile red, the in vivo fluorescence of the whole cell was visualized by fluorescence microscopy (excitation: 450 to 590 nm and emission: 520 nm). Intensity of the relative in vivo fluorescence was measured using a fluorescence spectrophotometer at excitation and emission wavelengths of 485 and 590 nm, respectively. Lipid content was determined gravimetrically and the fluorescence of the extract was measured using the microemulsion method at emission and excitation wavelengths of 540 and 617 nm. The equivalent oil content of the extracted lipid was correlated to the fluorescence of pure olive oil using the microemulsion method. Cellular in vivo fluorescence of stained cells (ex: 485 nm and em: 590 nm), fluorescence of extracted lipid (ex: 540 nm and em: 617 nm) and gravimetrically determined lipid were linearly correlated. This suggests that Nile red can serve as a vital stain which allows a relatively rapid method of determining the lipid content of microalgal samples and is as good as the gravimetric method used for lipid determination, eliminating the requirement for the toxic solvents and timeconsuming manipulations. Keywords: Nile red, microalgae, lipid, fluorescence

Anti-Influenza Virus Activities of Commercial Oregano oils and their Carriers

Commercial Oregano oils with high concentrations of carvacrol have been vigorously promoted as antiviral agents effective against colds and ‘flu, including the pandemic H1N1 virus. However there seems to be no evidence to support these claims. Furthermore, since carvacrol itself is known to be toxic, so-called “carrier oils”, such as olive oil, have been included in formulations to ameliorate the potential toxic effects. We compared the antiinfluenza virus activity of several preparations, with and without “carriers”, and pure olive oil and carvacrol, by means of quantitative assays for H1N1 influenza virus, and for cytotoxicity in human lung epithelial cells. A range of concentrations was evaluated, including those relevant to consumer applications. All five Oregano oils showed significant antiviral activity, as did olive oil by itself, although their potencies were not comparable to a standardized preparation of Echinacea purpurea. Carvacrol was also very active, but it was also strongly cytotoxic. In addition all the Oregano oils were more cytotoxic than Echinacea purpurea. Thus certain commercial Oregano oils do possess anti-influenza virus activities, although these are less than a potent standardized Echinacea preparation, and furthermore the toxicity of the oils to lung epithelial cells, at doses relevant to consumer applications, is a limiting factor in their usefulness for oral applications.

가정에서의 튀김유지 재사용과 보관에 따른 산패도 및 관능적 특성 평가

The purpose of this study was to determine the effects of the duration of frying and storage periods on physicochemical characteristics of various oils using at home. The materials used for the study consisted of four kinds of vegetable oils: soybean, canola, extra virgin olive and pure olive oils, and shortening. Chicken breasts were fried in oils heated at <TEX>$180^{\circ}C$</TEX>. The oils were stored with or without filtering and reused 3 times, during the 10 day period. The extra virgin and pure olive oils showed higher acid, peroxide value and yellowness than the other oils (p<0.05), but soybean oil showed the highest increase in acid, peroxide value and yellowness with reusing and storage. In sensory evaluation, the chicken breast fried with soybean oils remarkably decreased the overall acceptance. These results suggested that all frying oils are available because acid and peroxide values of the oils are lower than the standard level. However, reusing soybean oil should be noted with caution in that it is very easy to reduce rancidity, and extra virgin olive oil is not appropriate for frying.

In-vial liquid–liquid microextraction-capillary electrophoresis method for the determination of phenolic acids in vegetable oils

An in-vial liquid–liquid microextraction method was developed for the selective extraction of the phenolic acids (caffeic, gallic, cinnamic, ferulic, chlorogenic, syringic, vanillic, benzoic, p-hydroxybenzoic, 2,4-dihydroxybenzoic, o-coumaric, m-coumaric and p-coumaric) in vegetable oil samples. The optimised extraction conditions for 20g sample were: volume of diluent (n-hexane), 2mL; extractant, methanol: 5mM sodium hydroxide (60:40; v/v); volume of extractant, 300μL (twice); vortex, 1min; centrifugation, 5min. Recoveries for the studied phenolic acids were 80.1–119.5%. The simultaneous determination of the phenolic acid extracts was investigated by capillary electrophoresis (CE). Separations were carried out on a bare fused-silica capillary (50μm i.d.×40cm length) involving 25mM sodium tetraborate (pH 9.15) and 5% methanol as CE background electrolyte in the normal polarity mode, voltage of 30kV, temperature of 25°C, injection time of 4s (50mbar) and electropherograms were recorded at 200nm. The phenolic acids were successfully separated in less than 10min. The validated in-vial LLME-CE method was applied to the determination of phenolic acids in vegetable oil samples (extra virgin olive oil, virgin olive oil, pure olive oil, walnut oil and grapeseed oil). The developed method shows significant advantages over the current methods as lengthy evaporation step is not required.

The effects of dietary long-chain essential fatty acids on growth and stress tolerance in pikeperch larvae (Sander lucioperca L.)

The nutritional requirements of pikeperch larvae have been sparsely examined. Dietary polyunsaturated fatty acids, arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may affect growth and physiological stress response in marine fish larvae, but these mechanisms have not received as much attention in freshwater fish. Pikeperch larvae were reared on Artemia from day 3 until 21 days posthatch. Artemia were enriched with six formulated emulsions, with inclusion of either fish oil, pure olive oil (POO) or olive oil supplemented with various combinations of ARA, EPA and DHA. Larval tissue FA was significantly related to the content in the diets, but larval growth was similar for all treatments. When exposed to stress by confinement in small tanks with culture tank water or saline water (15 g L−1.), mortality in larvae treated with POO was significantly higher than in the remaining treatments while tissue cortisol contents in these fish seemed lower. The findings of a lower stress response in larvae fed POO may be related to the lower tissue content in these larvae of essential fatty acids especially DHA but also EPA and ARA.

Updating a Synchronous Fluorescence Spectroscopic Virgin Olive Oil Adulteration Calibration to a New Geographical Region

Detecting and quantifying extra virgin olive adulteration is of great importance to the olive oil industry. Many spectroscopic methods in conjunction with multivariate analysis have been used to solve these issues. However, successes to date are limited as calibration models are built to a specific set of geographical regions, growing seasons, cultivars, and oil extraction methods (the composite primary condition). Samples from new geographical regions, growing seasons, etc. (secondary conditions) are not always correctly predicted by the primary model due to different olive oil and/or adulterant compositions stemming from secondary conditions not matching the primary conditions. Three Tikhonov regularization (TR) variants are used in this paper to allow adulterant (sunflower oil) concentration predictions in samples from geographical regions not part of the original primary calibration domain. Of the three TR variants, ridge regression with an additional 2-norm penalty provides the smallest validation sample prediction errors. Although the paper reports on using TR for model updating to predict adulterant oil concentration, the methods should also be applicable to updating models distinguishing adulterated samples from pure extra virgin olive oil. Additionally, the approaches are general and can be used with other spectroscopic methods and adulterants as well as with other agriculture products.

Effects of Hexachlorocyclohexane (HCH-γ-Isomer, Lindane) Intoxication on the Proliferation and Apoptosis in Rat Testes

In this study, experimentally lindane-induced histopathological changes and proliferation and/or apoptosis in germ cells in the rat testes were investigated. A total of 40 healthy fertile 3-month-old male rats were used. Animals were divided into 4 groups, each containing 10 rats. Group 1 (control) was given only pure olive oil, Groups 2, 3 and 4 were administered lindane at 10, 20 and 40 mg/kg/bw, respectively, by gastric gavage for 30 days. Microscopically, degenerative changes were observed in the lindane-treated groups. For proliferative activity PCNA immunolabelling and for germ cells apoptosis TUNEL methods were performed. Although a strong PCNA positivity in the control group was observed, a gradual decrease was noted in the lindane-treated groups especially at higher doses. Significant increases of apoptosis were seen in the lindane-treated groups compared to the control group. A decrease in testosterone concentrations was observed in lindane-treated groups compared to the control group. The study indicates that high-dose lindane intoxication contributes to the suppression of spermatogenesis through a reduction of germ cell proliferation and an increase of germ cell death in rat testes.

Therapeutic Effects of Topical Application of Ozone on Acute Cutaneous Wound Healing

This study was undertaken to evaluate the therapeutic effects of topical ozonated olive oil on acute cutaneous wound healing in a guinea pig model and also to elucidate its therapeutic mechanism. After creating full-thickness skin wounds on the backs of guinea pigs by using a 6 mm punch biopsy, we examined the wound healing effect of topically applied ozonated olive oil (ozone group), as compared to the pure olive oil (oil group) and non-treatment (control group). The ozone group of guinea pig had a significantly smaller wound size and a residual wound area than the oil group, on days 5 (P<0.05) and 7 (P<0.01 and P<0.05) after wound surgery, respectively. Both hematoxylin-eosin staining and Masson-trichrome staining revealed an increased intensity of collagen fibers and a greater number of fibroblasts in the ozone group than that in the oil group on day 7. Immunohistochemical staining demonstrated upregulation of platelet derived growth factor (PDGF), transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF) expressions, but not fibroblast growth factor expression in the ozone group on day 7, as compared with the oil group. In conclusion, these results demonstrate that topical application of ozonated olive oil can accelerate acute cutaneous wound repair in a guinea pig in association with the increased expression of PDGF, TGF-β, and VEGF.

Radical Scavenging‐Linked Antioxidant Activity of Ethanolic Extracts of Diverse Types of Extra Virgin Olive Oils

The present study evaluated the radical scavenging-linked antioxidant activity of hexane/80% ethanol extracts from several types of extra virgin olive oils (EVOOs) derived from varieties arbequina, hojiblanca, picual, their blends, and pure olive oil (POO). The antioxidant potential of the olive oil extracts was assessed by radical scavenging assays using DPPH (2, 2-diphenyl-1-picrylhydrazyl), ABTS (2, 2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid), and hydroxyl radical, as well as hydrogen peroxide and superoxide anion inhibitory activities. Electron donating ability (EDA) using DPPH assay of 80% ethanol extracts from EVOOs, except arbequina oil, was significantly higher than POO. EDA was markedly higher in blended and picual EVOOs than the extracts from arbequina and hojiblanca EVOOs (P < 0.05). Similarly, ABTS radical scavenging activity of the extracts from the EVOOs was in order of picual EVOO > blended EVOO > hojiblanca EVOO >or= POO >or= arbequina EVOO. Further, the superoxide anion scavenging activity of blended, picual, and arbequina EVOOs was significantly higher than that of hojiblanca EVOO and POO, which were barely detectable. Hydroxyl radical scavenging activity of arbequina and hojiblanca was higher than that of blended, picual EVOOs, and POO. In addition, hydrogen peroxide scavenging activity of the extracts from blended, arbequina, hojiblanca, picual EVOOs, and POO was 63.1 +/- 3.1%, 44.4 +/- 10.2%, 52.0 +/- 2.7%, 71.8 +/- 2.5%, and 35.7 +/- 10.0%, respectively. Our results indicate that ethanol extracts of several EVOOs contained higher radical scavenging and antioxidant activity than the POO. This antioxidant potential is partly due to the phenolic compounds present in different olive oil grade and is influenced by cultivar type.

Effects of Retinoic Acid on the Expressions of Vangl1 and Vangl2 in Mouse Fetuses

This study reports the effects of retinoic acid on the spatiotemporal expressions of Vangl1 and Vangl2 in mouse fetuses. A single dose of 120 mg/kg body weight of all-trans-retinoic acid suspended in olive oil was administered intragastrically to each pregnant BALB/C mice on embryonic day (E) 9.5 (group 1, G1) or E10.5 (group 2, G2); mice treated with pure olive oil on E9.5 or E10.5 served as control groups. The expression of Vangl1 and Vangl2 in fetuses was investigated by reverse transcriptase PCR (RT-PCR) and their spatial and temporal expression was detected by whole-mount in situ hybridization (WISH) on E10.5, E11.5, E13.5, E15.5, E17.5, and E19.5, respectively. The study indicated that the incidence of neural tube defects (NTDs) in live birth and craniofacial NTD rate were significantly higher in G1 (100% and 25.6%) than that in G2 (78.2% and 5.7%), both P<0.01. Vangl1 and Vangl2 were strongly expressed throughout neurulation in embryos of control groups. G1 embryos exhibited a dramatic downregulation of Vangl1 and Vangl2 expression from cranial regions to posterior neuropore compared with the control group of G1 (all P<0.01). In contrast, both transcripts in G2 embryos were significantly downregulated and weakly expressed in whole embryos on E11.5 and in the spinal region of the neural tube from E15.5 to E19.5, but moderately downregulated in the cranial region of the neural tube from E15.5 to E19.5 (all P<0.01). In conclusion, Vangl1 and Vangl2 transcript downregulation might be implicated in the occurrence of mouse NTDs induced by retinoic acid.

국내 유통되는 퓨어 및 정제 올리브유의 이화학적 특성 및 향기 분석

국내 시중에서 유통되는 국내외 브랜드의 퓨어 및 정제 올리브유에 대한 이화학적 특성 및 이들의 향기 성분을 비교 분석하였다. 총 7종의 퓨어 및 정제 올리브유의 지방산 조성을 비교한 결과 palmitic(16:0, 10.2~16.8 mole%), palmitoleic(16:1, 0.7~2.4 mole%), stearic(18:0, 1.9~3.0 mole%), oleic(18:1, 61.2~74.7 mole%), linoleic(18:2, 9.4~18.0 mole%) 및 linolenic acid(18:3, 0.5~0.9 mole%)로 분석되었다. 색도 분석에서 퓨어 및 정제 올리브유의 L*값은 92.2~99.0, a*값은 -22.2~-3.2, b*값은 18.5~55.0을 나타내었다. 이들의 총 페놀 함량 측정 결과 국내 브랜드 퓨어 올리브유에서는 2.2~13.3 ㎎/100 g, 수입 브랜드 퓨어 및 정제 올리브유에서는 1.9~5.1 ㎎/100 g으로 나타났고, α-토코페롤함량은 7.91~13.88 ㎎/100 g로 조사되었다. 퓨어 및 정제 올리브유 시료들의 초기 POV는 6.83~20.31 meq/kg의 수치를 보였고, 이들의 induction period time은 17.37~34.72 hr로 나타났다. 주요 향 성분의 구별을 위해 SPME-GC/MS 분석을 실시한 결과, 올리브유의 주요 향 성분으로 acetic acid, hexanal, heptanal, 2,4-dimethyl-heptane 등이 동정되었고, MOS 유형의 전자코를 이용하여 퓨어 및 정제 올리브유 향기패턴에 대한 주성분분석을 한 결과, 이들의 원산지별과 국내ㆍ수입 브랜드 및 혼합율에 의한 향기 성분 패턴 경향성을 찾아보기 어려웠다.

Hydrolysis of olive oil catalyzed by surfactant-coatedCandida rugosa lipase in a hollow fiber membrane reactor

In this study, we invetigated the hydrolysis of olive oil catalyzed by a surfactant-coatedCandida rugosa lipase in a hydrophilic polyacrylonitrile hollow fiber membrane reactor and then compared the results to those using the native lipase. The organic phase was passed through the hollow inner fibers of the reactor and consisted of either the coated lipase and olive oil dissolved in isooctane or the coated lipase dissolved in pure olive oil. The aqueous phase was pumped through the outer space. After 12 h and with conditions of 30°C, 0.12 mg enzyme/mL and 0.62 M olive oil, the substrate conversion of the coated lipase reached 60%. This was twice the conversion for the same amount of native lipase that was pre-immobilized on the membrane surface. When using pure olive oil, after 12 h the substrate conversion of the coated lipase was 50%. which was 1.4 times higher than that of the native lipase.

Effects ofPicrorrhizaRhizoma Water Extracts on the Subacute Liver Damages Induced by Carbon Tetrachloride

The hepatoprotective activity of Picrorrhiza rhizoma (PR) water extract was evaluated on carbon tetrachloride (CCl(4))-induced subacute hepatic damage, induced by subcutaneous injection of CCl(4) (0.15 mL/kg of body weight) in pure olive oil (7.92%, vol/vol) three times a week for 10 weeks. Animals were sacrificed 10 weeks after oral administration of PR extracts at 50, 100, or 200 mg/kg or silymarin at 100 mg/kg, which were administered simultaneously with CCl(4); changes in body weight, liver weight, and serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were observed along with differences in liver histopathology and histomorphometry. In addition, liver malondialdehyde as an index for lipid peroxidation, hydoxyproline as an index for collagen synthesis, and protein content were determined. Ten weeks of CCl(4) injections caused subacute hepatic damage, featuring significantly less body weight gain and hepatic protein contents and higher liver weight, serum AST and ALT levels, and hepatic malondialdehyde and hydroxyproline contents with subacute hepatic damage-related histopathology of the liver. However, the CCl(4)-induced toxic effects were dramatically and dose-dependently inhibited by PR extract treatment. Thus oral administration of PR extracts significantly reduced CCl(4)-induced subacute hepatic damage in rats, probably by exerting a protective effect against hepatocellular necrosis via its free radical scavenging ability.

Partial Least Squares Processing of Near‐Infrared Spectra for Discrimination and Quantification of Adulterated Olive Oils

Abstract A new processing based on partial least squares (PLS) algorithm for the discrimination and determination of adulterants in pure olive oil using near‐infrared (NIR) spectroscopy has been introduced. The 280 adulterations of olive oil with corn oil (n=70), hazelnut oil (n=70), soya oil (n=70), and sunflower oil (n=70) were prepared, and their NIR spectra in the region 12,000–4550 cm−1 were collected. The 70 spectra of each adulteration of olive oil were divided into two sets, 50 spectra for a calibration set and 20 spectra for a prediction set. The spectra of a total calibration set (n=200) were separated into individual adulterant calibration sets (ni=50, i=corn, hazelnut, soya, sunflower) by using discriminant PLS (DPLS) analysis, and PLS calibration models for the quantification of adulterants with corn oil, hazelnut oil, soya oil, or sunflower oil were developed separately. A variety of wavelength ranges and data pretreatments were examined for obtaining optimal results for the discrimination and quantification objects. Four PLS models for differentiating the adulterant types were evaluated by classifying the NIR spectra of a total prediction set (n=80) into known adulterant types. Then, these known adulterant spectra were analyzed by the PLS calibration models developed for each type to determine the content of an adulterant in pure olive oil. The results of evaluation revealed that the processing reported in this article works excellently for the discrimination and quantification of the adulterations of olive oil.

Excitation−Emission Fluorescence Spectroscopy Combined with Three-Way Methods of Analysis as a Complementary Technique for Olive Oil Characterization

This paper shows the potential of excitation-emission fluorescence spectroscopy (EEFS) and three-way methods of analysis [parallel factor analysis (PARAFAC) and multiway partial least-squares (N-PLS) regression] as a complementary technique for olive oil characterization. The fluorescence excitation-emission matrices of a set of Spanish extra virgin, virgin, pure, and olive pomace oils were measured, and the relationship between them and some of the quality parameters of olive oils (peroxide value, K232, and K270) was studied. N-PLS was found to be more suitable than PARAFAC combined with multiple linear regression for correlating fluorescence and quality parameters, yielding better fits and lower prediction errors. The best results were obtained for predicting K270. EEFS allowed detection of extra virgin olive oils highly degraded at early stages (with high peroxide value) and little oxidized pure olive oils (with low K270). The proposed methodology may be used as an aid to analyze doubtful samples.

Caffeic acid phenethyl ester protects kidneys against carbon tetrachloride toxicity in rats

Caffeic acid phenethyl ester (CAPE), an active component of propolis produced by honeybees, exhibits antioxidant and anti-inflammatory properties. The aim of this study was to investigate possible protective effects of CAPE on carbon tetrachloride (CCl 4)-induced renal damage in rats. A total of 24 animals were divided into three equal groups: the control rats received pure olive oil subcutaneously, rats in the second group were injected with CCl 4 (0.5 ml/kg, s.c. in olive oil) and rats in the third group were injected with CCl 4 (0.5 ml/kg) plus CAPE (10 μmol/kg, i.p.) every other day for one month. At the end of the experimental period, the animals were sacrificed and blood samples were collected. Serum urea and creatinine levels and renal malondialdehyde (MDA) contents were determined. Histopathological examination of the kidney was also performed using light microscopic methods. It was found that kidney MDA levels were increased significantly following CCl 4 exposure and this increase was significantly inhibited by CAPE treatment, while no significant changes were observed in serum urea and creatinine levels. CCl 4 administration alone also caused histopathologically prominent damage in the kidney compared to the control group. Glomerular and tubular degeneration, interstitial mononuclear cell infiltration and fibrosis, and vascular congestion in the peritubular blood vessels were observed in the renal cortex. With exception of rare vascular congestions, these histopathological changes were disappeared in rats treated with CCl 4 plus CAPE. In view of the present findings, it is suggested that CAPE protects kidneys against CCl 4 toxicity.

Cluster Analysis Applied to the Exploratory Analysis of Commercial Spanish Olive Oils by Means of Excitation−Emission Fluorescence Spectroscopy

Olive oil fluorescence is related to oil composition. Here it is shown that the natural clustering of different types of commercial Spanish olive oils depends on their fluorescence excitation-emission matrices (EEMs). Fifty-six commercial samples of olive oil (29 virgin olive oils, 20 pure olive oils, and 7 olive-pomace oils) were used. The clustering method was hierarchical agglomerative clustering using the Euclidean distance as a similarity measure and the average linkage. Two spectral ranges were considered (which either contained the fluorescence peak of the chlorophylls or did not), and various methods for preprocessing the fluorescence spectra were compared. The oils were clearly distinguished using the unfolded EEMs measured between lambda(ex) = 300-400 nm and lambda(em) = 400-600 nm. The optimal preprocessing was normalization of the unfolded spectra followed by column autoscaling. Also shown are the advantages of using second-order data (EEMs) instead of first-order data (a single fluorescence spectrum) for each sample.