An Analytical Method for the Biomonitoring of Mercury in Bees and Beehive Products by Cold Vapor Atomic Fluorescence Spectrometry.

Bees and their products are useful bioindicators of anthropogenic activities and could overcome the deficiencies of air quality networks. Among the environmental contaminants, mercury (Hg) is a toxic metal that can accumulate in living organisms. The first aim of this study was to develop a simple analytical method to determine Hg in small mass samples of bees and beehive products by cold vapor atomic fluorescence spectrometry. The proposed method was optimized for about 0.02 g bee, pollen, propolis, and royal jelly, 0.05 g beeswax and honey, or 0.1 g honeydew with 0.5 mL HCl, 0.2 mL HNO3, and 0.1 mL H2O2 in a water bath (95 °C, 30 min); samples were made up to a final volume of 5 mL deionized water. The method limits sample manipulation and the reagent mixture volume used. Detection limits were lower than 3 µg kg-1 for a sample mass of 0.02 g, and recoveries and precision were within 20% of the expected value and less than 10%, respectively, for many matrices. The second aim of the present study was to evaluate the proposed method's performances on real samples collected in six areas of the Lazio region in Italy.

Formation, structural characteristics and physicochemical properties of beeswax oleogels prepared with tea polyphenol loaded gelators.

In this study, a tea polyphenol (TP) loaded beeswax gelator (TP gelator) was constructed and incorporated into soybean oil to improve the oxidative stability of oleogels. The effects of TP on the structure and storage stability of oleogels were investigated. The TP gelator prepared by embedding TP into beeswax improved the dispersity of TP in lipids. The thermal characteristics and X-ray diffraction analysis showed that the components of the TP gelator coexisted homogeneously and TP was well dispersed in beeswax. The Fourier-transform infrared spectra indicated that the phenolic hydroxyl group of TP had intermolecular force with the quaternary ammonium nitrogen in the choline portion of soybean lecithin. The formation of needle-like crystals by beeswax restricted the flow of liquid oil, and TP did not participate in the construction of the internal network structure of the oleogel. In the accelerated storage experiment at 60 °C, the peroxide value of the TP loaded oleogel decreased by 60.6% at the end of the storage period compared with soybean oil. TP was successfully embedded in the oleogel without changing its structure, which not only solved the problem of poor dispersion of TP in oil, but also showed a significant inhibitory effect on lipid oxidation.

Comprehensive two-dimensional gas chromatography-high resolution mass spectrometry with complementary ionization methods in the study of 5000-year-old mummy.

RATIONALE: Mummification is one of the defining customs of ancient Egypt. The nuances of the embalming procedure and the composition of the embalming mixtures have attracted the attention of scientists and laypeople for a long time. Modern analytical tools make mummy studies more efficient. METHODS: Comprehensive two-dimensional gas chromatography-high resolution mass spectrometry (GCxGC/HRMS) with complementary ionization methods (electron ionization, positive chemical ionization, and electron capture negative ionization [ECNI]) with a Pegasus GC-HRT+4D instrument was used to identify embalming components in the mummy from the Pushkin Museum of Fine Arts acquired in 1913 in London at the de Rustafjaell sale. The mummy dates back to the late Predynastic period (direct accelerator mass spectrometry-dating 3356-3098 bc), being one of the oldest in the world. RESULTS: The results showed the complexity of the embalming mixtures that were already in use 5000 years ago. Several hundred organic compounds were identified in the mummy samples. Various types of hydrocarbons (triterpanes, steranes, isoprenoid, and polycyclic aromatic hydrocarbons) prove the presence of petroleum products. Iodinated compounds detected using ECNI define oils of marine origin, whereas esters of palmitic acid indicate the use of beeswax. The nature of the discovered components of conifer tar proves that the preliminary processing of conifer resins involved heating. GCxGC/HRMS also allowed a number of modern contaminants (phthalates, organophosphates, and even DDT) to be identified. CONCLUSIONS: Application of a powerful GCxGC/HRMS technique with complementary ionization methods allowed significant widening of the range of organic compounds used for mummification that could be identified. The complexity of the embalming mixtures supports the hypothesis of the high social status of the child made on the basis of the preliminary study of the mummy.

Fossil leaf wax hydrogen isotopes reveal variability of Atlantic and Mediterranean climate forcing on the southeast Iberian Peninsula between 6000 to 3000 cal. BP.

Many recently published papers have investigated the spatial and temporal manifestation of the 4.2 ka BP climate event at regional and global scales. However, questions with regard to the potential drivers of the associated climate change remain open. Here, we investigate the interaction between Atlantic and Mediterranean climate forcing on the south-eastern Iberian Peninsula during the mid- to late Holocene using compound-specific hydrogen isotopes from fossil leaf waxes preserved in marine sediments. Variability of hydrogen isotope values in the study area is primarily related to changes in the precipitation source and indicates three phases of increased Mediterranean sourced precipitation from 5450 to 5350 cal. BP, from 5150 to 4300 cal. BP including a short-term interruption around 4800 cal. BP, and from 3400 to 3000 cal. BP interrupted around 3200 cal. BP. These phases are in good agreement with times of prevailing positive modes of the North Atlantic Oscillation (NAO) and reduced storm activity in the Western Mediterranean suggesting that the NAO was the dominant modulator of relative variability in precipitation sources. However, as previously suggested other modes such as the Western Mediterranean Oscillation (WeMO) may have altered this overall relationship. In this regard, a decrease in Mediterranean moisture source coincident with a rapid reduction in warm season precipitation during the 4.2 ka BP event at the south-eastern Iberian Peninsula might have been related to negative WeMO conditions.

Properties of margarines prepared from soybean oil oleogels with mixtures of candelilla wax and beeswax.

The aim of this study was to examine the physical properties of margarines prepared from oleogels with binary mixtures of candelilla wax (CDW) and beeswax (BW) in soybean oil. Some of the margarines made from oleogels with mixtures of CDW and BW had higher firmness than those made with one wax. For example, a 3% wax margarine made with 25% CDW and 75% BW had significantly higher firmness (0.97 N) than those with 100% CDW (0.59 N) and with 100% BW (0.11 N). Differential scanning calorimetry (DSC) and solid fat content (SFC) analyses revealed eutectic melting properties for binary wax margarines, which may be desirable since wax oleogel-based margarines often have higher melting points than conventional margarines. For example, the major melting point of 3% wax margarine made with 50% CDW and 50% BW was 43.85 °C, while for margarines made with 100% CDW or 100% BW, the melting points were at 46.00% and 47.61 °C, respectively. SFC was lowest for margarines with 50 or 75% BW; for example, 3% wax margarine with 25% CDW and 75% BW had 0.72% SFC at 40 °C while those with 100% CDW and 100% BW had 1.19 and 1.13% SFC, respectively. However, dropping point constantly decreased with increasing BW ratios. This study demonstrated that by mixing two waxes, the firmness of oleogel-based margarines could be increased, and the melting point could be tailored by the ratio of two waxes. PRACTICAL APPLICATION: This study demonstrated that firmness and melting properties of margarines prepared from wax-oleogels can be improved by mixing two waxes, making their practical application more feasible. Firmness of margarines prepared with oleogels of binary mixtures of candelilla wax and beeswax were higher than those with pure waxes. The melting point of wax oleogel-based margarines was decreased by use of binary mixtures of candelilla wax and beeswax.

Stabilization of peanut butter by rice bran wax.

To improve stability of peanut butter, rice bran wax (RBX) was added into peanut butter as a stabilizer by formation of organogel. Effects of addition of RBX, heating temperature, and cooling temperature on stabilization effect of peanut butter by RBX were investigated. The optimum conditions were as follow: addition of RBX at 4.0 wt%; heating temperature at 85 °C, and cooling temperature at 20 °C. Under the optimum conditions, the oil loss of peanut butter decreased from 12.19% to 4.04%, and the adhesiveness of peanut butter increased from 23.5 to 165.9 g·s. After storage for 25 weeks, the acid value (AV) of peanut butter prepared under the optimum conditions increased from 0.65  to 0.80 mg/g, and the peroxide value (PV) increased from 0.116 to 0.127 meq/kg. However, the AV of natural peanut butter increased to 1.73 mg/g, and PV increased to 0.178 meq/kg. The confocal laser scanning microscope images showed that the cooling temperature significantly affected crystallization of RBX and distribution of solid particles. When RBX formed needle-like crystals and peanut solid particles were evenly distributed in the oil phase, stable peanut butter was obtained. These results suggested that the RBX was an effective stabilizer for peanut butter. PRACTICAL APPLICATION: Oil separation often occurred to peanut butter during storage, which reduced the sensory quality of peanut butter and shortened its shelf life. This study stabilized peanut butter by addition of RBX based on the formation of organogel, which was of great practical significance to improve the shelf life of peanut butter.

Structure and morphology of cellulose fibers in garlic skin.

The knowledge of the texture and morphology of cellulose is essential for reliable modelling of cell growth and mechanical resistance of vegetal systems. Microscopic observations on thin layers of the skin of Allium sativum have shown elongated structures (i.e. cellulose fibers) imbedded in a matrix of more or less rounded cells. Examination by an optical polarizing microscope (OPM) has shown an intermittent high and low birefringence along fibers. Transversal regions with a reduced brightness along fibers are expected to contain a higher amount of amorphous lignin, hemicelluloses and waxes, some of which might also be birefringent, but at a much lower degree than cellulose. Scanning electron microscopy (SEM) has also evidenced an alternating growth of the fibers. Moreover, the negative sign of birefringence suggests a parallel orientation of cellulose nanofibrils transversally to the fiber axis. The characteristic modulation of intensity along lignocellulosic fibers can be due to variation of the cellulose concentration or orientation, perhaps caused by circadian cycles of temperature and light during growth. Indeed, imperfect orthogonal light can be totally reflected at the interface between regions with different values of the refractive index, contributing to the optical effect of banding.

Comparative analysis of the chemical composition and water permeability of the cuticular wax barrier in Welsh onion (Allium fistulosum L.).

Cuticular wax is a hydrophobic barrier between the plant surface and the environment that effectively reduces the loss of water. The surface of Welsh onion leaves is covered with wax. To explain the relationship between wax composition and water loss, we conducted this experiment. The water permeability and wax composition of leaves were determined by chemical and GC-MS methods. We performed a comparative analysis of the differences between the two cultivars and analyzed the relationship between water permeability and waxy components. Overall, the permeability to water was higher in 'Zhangqiu' than in 'Tenko'. The wax amount of 'Tenko' was 1.28-fold higher than that of 'Zhangqiu' and was primarily explained by the much larger amounts of ketones and alcohols in the former. Among the waxy components, C29 ketones were most abundant. There were substantial discrepancies in wax composition, total wax content, and water permeability between the two cultivars. The main reason for the discrepancy in water permeability may be the significantly lower aliphatic fraction in 'Zhangqiu' than in 'Tenko'. This study makes a vital contribution to drought resistance research on allium plants.

Canola oil/candelilla wax oleogel improves texture, retards staling and reduces in vitro starch digestibility of maize tortillas.

BACKGROUND: Maize tortilla staling is a major drawback that affects its commercialization and consumption, and so novel methods for retarding staling are continuously being explored. The present study evaluated the effect of adding a canola oil/candelilla wax oleogel (CWO; 0. 2, 4 and 6 g 100 g-1 ) to a basic masa formulation (water, 60 g 100 g-1 ; nixtamalized maize flour, 40 g 100 g-1 ) on the texture, staling and in vitro starch digestibility of maize tortillas made using a hot plate (200 °C). RESULTS: Textural analysis showed that CWO reduced hardness and increased the tensile strength of tortillas. Fourier transform infrared analysis indicated that the retrogradation of starch chains, quantified in terms of the intensity ratio 1047/1022, was reduced by oleogel incorporation. In vitro starch digestibility tests showed that tortillas containing CWO had lower readily digestible and slowly digestible starch fractions compared to the control tortilla without oleogel. CONCLUSION: The formation of amylose-lipid inclusion complexes and the formation of an oily physical barrier around starch granules were postulated as mechanisms underlying the reduced starch digestibility. © 2019 Society of Chemical Industry.

Compositional and morphological analyses of wax in northern wild berry species.

Aerial surfaces of plants are covered by a waxy cuticle protecting plants from excessive water loss and UV light. In the present study, composition and morphology of cuticular waxes of northern wild berry species bilberry (Vaccinium myrtillus L.), lingonberry (V. vitis-idaea L.), bog bilberry (V. uliginosum L.) and crowberry (Empetrum nigrum L.) were investigated. Scanning electron microscopy (SEM) revealed differences in epicuticular wax morphology, and gas chromatography-mass spectrometry (GC-MS) analysis confirmed variation in chemical composition of cuticular waxes between the berry species. The dominant compounds in bilberry and lingonberry cuticular waxes were triterpenoids, while fatty acids and alkanes were the dominant ones in bog bilberry and crowberry, respectively. Wax extracted by supercritical fluid extraction (SFE) from industrial press cakes of bilberry and lingonberry contained linoleic acid and γ-linolenic acid as the dominant compounds. Furthermore, in vitro sun protection factor (SPF) of berry waxes depicted good UV-B absorbing capacities.

The potential application of plant wax markers from alfalfa for estimating the total feed intake of sheep.

Estimating the feed intake of grazing herbivores is critical for determining their nutrition, overall productivity and utilization of grassland resources. A 17-day indoor feeding experiment was conducted to evaluate the potential use of Medicago sativa as a natural supplement for estimating the total feed intake of sheep. A total of 16 sheep were randomly assigned to four diets (four sheep per diet) containing a known amount of M. sativa together with up to seven forages common to typical steppes. The diets were: diet 1, M. sativa + Leymus chinensis + Puccinellia distans; diet 2, species in diet 1 + Phragmites australis; diet 3, species in diet 2 + Chenopodium album + Elymus sibiricus; and diet 4, species in diet 3 + Artemisia scoparia + Artemisia tanacetifolia. After faecal marker concentrations were corrected by individual sheep recovery, treatment mean recovery or overall recovery, the proportions of M. sativa and other dietary forages were estimated from a combination of alkanes and long-chain alcohols using a least-square procedure. Total intake was the ratio of the known intake of M. sativa to its estimated dietary proportion. Each dietary component intake was obtained using total intake and the corresponding dietary proportions. The estimated values were compared with actual values to assess the estimation accuracy. The results showed that M. sativa exhibited a distinguishable marker pattern in comparison to the other dietary forage species. The accuracy of the dietary composition estimates was significantly (P < 0.001) affected by both diet diversity and the faecal recovery method. The proportion of M. sativa and total intake across all diets could be accurately estimated using the individual sheep or the treatment mean recovery methods. The largest differences between the estimated and observed total intake were 2.6 g and 19.2 g, respectively, representing only 0.4% and 2.6% of the total intake. However, they were significantly (P < 0.05) biased for most diets when using the overall recovery method. Due to the difficulty in obtaining individual sheep recovery under field conditions, treatment mean recovery is recommended. This study suggests that M. sativa, a natural roughage instead of a labelled concentrate, can be utilized as a dietary supplement to accurately estimate the total feed intake of sheep indoors and further indicates that it has potential to be used in steppe grassland of northern China, where the marker patterns of M. sativa differ markedly from commonly occurring plant species.

Carnauba wax uses in food - A review.

Carnauba wax is widely used in food, due to its physico-chemical characteristics with a predominance of esters and inert and stable components. Even with so many possibilities for the use of carnauba wax in food, there are still a large number of researchers around the world searching for new applications and a demand for new products with new technologies to improve existing ones. Recently, many parts of research which focus on the use of this wax in conservation and food processing have been carried out, some of which highlight the role of this wax in the microencapsulation of flavours, in preparing edible films and super hydrophobic and biodegradable packaging. This paper discusses the use of carnauba wax in food, including the extraction process of the wax, its chemical and physical characteristics, safety aspects, national and international law and permitted uses, along with the presentation of the main scientific research conducted.

An assessment of pesticide exposures and land use of honey bees in Virginia.

Large-scale honey bee colony loss threatens pollination services throughout the United States. An increase in anthropogenic pressure may influence the exposure of hives to household and agricultural pesticides. The objective of this survey was to provide an assessment of the risk of exposure to commonly used pesticides to honey bee colonies in Virginia in relation to land use. Adult honey bee, pollen, and wax samples from colonies throughout Virginia were evaluated for pyrethroid, organophosphate, organochlorine, and triazine pesticides using gas chromatography-mass spectrometry analysis. Of the 11 pesticides analyzed, nine were detected in one or more hive matrices. The probability of detecting a pesticide in pollen was less in forests than in pasture, agriculture, or urban landscapes. Coumaphos and fluvalinate were significantly more likely to be detected across all matrices with concentrations in wax as high as 15500 and 6970 ng/g (dry weight), respectively, indicating the need for further research on the potential effects of miticide accumulation in wax to larval and adult bees.

Neonicotinoids transference from the field to the hive by honey bees: Towards a pesticide residues biomonitor.

The beehive as a quantitative monitor of pesticide residues applied over a soybean crop was studied through a semi field experiment of controlled exposure of honey bees to pesticides in macro tunnels. The distribution within exposed beehives of pesticides commonly used in soybean plantation, was assessed. Residue levels of insecticides in soybean leaves, honey bees, wax, honey and pollen were analyzed. The transference from pesticides present in the environment into the beehive was evidenced. The obtained results allow relating pesticide concentrations present in the environment with traces found in foraging bees. Therefore, pesticide transference ratios could be calculated for each detected compound (acetamiprid, imidacloprid and thiamethoxam) which showed a linear inverse trend with their 1-octanol/water partition coefficient (Kow). The least transferred pesticide to the hive (acetamiprid) has the highest vapor pressure (Vp). This study gives new insights on the usefulness of monitoring the environment through beehives aiming to evaluate if agroecosystems remain sustainable. It also contributes to generate valuable information for model building aiming to predict environmental quality through beehive's analysis.

Boron and Coumaphos Residues in Hive Materials Following Treatments for the Control of Aethina tumida Murray.

In the search of alternatives for controlling Aethina tumida Murray, we recently proposed the BAA trap which uses boric acid and an attractant which mimics the process of fermentation caused by Kodamaea ohmeri in the hive. This yeast is excreted in the feces of A. tumida causing the fermentation of pollen and honey of infested hives and releasing compounds that function as aggregation pheromones to A. tumida. Since the boron is the toxic element in boric acid, the aim of this article is to assess the amount of boron residues in honey and beeswax from hives treated with the BAA trap. For this aim, the amount of bioaccumulated boron in products of untreated hives was first determined and then compared with the amount of boron of products from hives treated with the BAA trap in two distinct climatic and soil conditions. The study was conducted in the cities of Padilla, Tamaulipas, and Valladolid, Yucatan (Mexico) from August 2014 to March 2015. The quantity of boron in honey was significantly less in Yucatan than in Tamaulipas; this agrees with the boron deficiency among Luvisol and Leptosol soils found in Yucatan compared to the Vertisol soil found in Tamaulipas. In fact, the honey from Yucatan has lower boron levels than those reported in the literature. The BAA treatment was applied for four months, results show that the BAA trap does not have any residual effect in either honey or wax; i.e., there is no significant difference in boron content before and after treatment. On the other hand, the organophosphate pesticide coumaphos was found in 100% of wax samples and in 64% of honey samples collected from Yucatan. The concentration of coumaphos in honey ranges from 0.005 to 0.040 mg/kg, which are below Maximum Residue Limit (MRL) allowed in the European Union (0.1 mg/kg) but 7.14% of samples exceeded the MRL allowed in Canada (0.02 mg/kg).

Widespread exploitation of the honeybee by early Neolithic farmers.

The pressures on honeybee (Apis mellifera) populations, resulting from threats by modern pesticides, parasites, predators and diseases, have raised awareness of the economic importance and critical role this insect plays in agricultural societies across the globe. However, the association of humans with A. mellifera predates post-industrial-revolution agriculture, as evidenced by the widespread presence of ancient Egyptian bee iconography dating to the Old Kingdom (approximately 2400 BC). There are also indications of Stone Age people harvesting bee products; for example, honey hunting is interpreted from rock art in a prehistoric Holocene context and a beeswax find in a pre-agriculturalist site. However, when and where the regular association of A. mellifera with agriculturalists emerged is unknown. One of the major products of A. mellifera is beeswax, which is composed of a complex suite of lipids including n-alkanes, n-alkanoic acids and fatty acyl wax esters. The composition is highly constant as it is determined genetically through the insect's biochemistry. Thus, the chemical 'fingerprint' of beeswax provides a reliable basis for detecting this commodity in organic residues preserved at archaeological sites, which we now use to trace the exploitation by humans of A. mellifera temporally and spatially. Here we present secure identifications of beeswax in lipid residues preserved in pottery vessels of Neolithic Old World farmers. The geographical range of bee product exploitation is traced in Neolithic Europe, the Near East and North Africa, providing the palaeoecological range of honeybees during prehistory. Temporally, we demonstrate that bee products were exploited continuously, and probably extensively in some regions, at least from the seventh millennium cal BC, likely fulfilling a variety of technological and cultural functions. The close association of A. mellifera with Neolithic farming communities dates to the early onset of agriculture and may provide evidence for the beginnings of a domestication process.

Direct surface analysis coupled to high-resolution mass spectrometry reveals heterogeneous composition of the cuticle of Hibiscus trionum petals.

Plant cuticle, which is the outermost layer covering the aerial parts of all plants including petals and leaves, can present a wide range of patterns that, combined with cell shape, can generate unique physical, mechanical, or optical properties. For example, arrays of regularly spaced nanoridges have been found on the dark (anthocyanin-rich) portion at the base of the petals of Hibiscus trionum. Those ridges act as a diffraction grating, producing an iridescent effect. Because the surface of the distal white region of the petals is smooth and noniridescent, a selective chemical characterization of the surface of the petals on different portions (i.e., ridged vs smooth) is needed to understand whether distinct cuticular patterns correlate with distinct chemical compositions of the cuticle. In the present study, a rapid screening method has been developed for the direct surface analysis of Hibiscus trionum petals using liquid extraction surface analysis (LESA) coupled with high-resolution mass spectrometry. The optimized method was used to characterize a wide range of plant metabolites and cuticle monomers on the upper (adaxial) surface of the petals on both the white/smooth and anthocyanic/ridged regions, and on the lower (abaxial) surface, which is entirely smooth. The main components detected on the surface of the petals are low-molecular-weight organic acids, sugars, and flavonoids. The ridged portion on the upper surface of the petal is enriched in long-chain fatty acids, which are constituents of the wax fraction of the cuticle. These compounds were not detected on the white/smooth region of the upper petal surface or on the smooth lower surface.

QuEChERS Adaptability for the Analysis of Pesticide Residues in Beehive Products Seeking the Development of an Agroecosystem Sustainability Monitor.

Beehive products could be powerful monitors of pesticide residues originating in agroecosystems during production cycles. Their ready availability provides enough samples to perform analytical determinations, but their chemical complexity makes residue analysis a real challenge. Taking advantage of the plasticity of QuEChERS coupled to LC-MS/MS, validated methodologies were developed for bees, honey, beeswax, and pollen and applied to real samples for the simultaneous determination of 19 of the most employed pesticides in intensive cropping fields. Beehives placed in Uruguayan agroecosystems accumulated the pesticides thiacloprid, imidacloprid, methomyl, carbaryl, hexythiazox, azoxystrobin, pyraclostrobin, tebuconazole, and haloxyfop-methyl at 0.0001-0.01 mg/kg levels. The oscillations on the amount and occurrence of residue findings for specific apiaries were correlated statistically with the sampling season and the agroecosystem where the beehives were located, showing the potential of bees and bee products to record relevant information to survey the chemicals applied in their surroundings.

Drought, agricultural adaptation, and sociopolitical collapse in the Maya Lowlands.

Paleoclimate records indicate a series of severe droughts was associated with societal collapse of the Classic Maya during the Terminal Classic period (∼800-950 C.E.). Evidence for drought largely derives from the drier, less populated northern Maya Lowlands but does not explain more pronounced and earlier societal disruption in the relatively humid southern Maya Lowlands. Here we apply hydrogen and carbon isotope compositions of plant wax lipids in two lake sediment cores to assess changes in water availability and land use in both the northern and southern Maya lowlands. We show that relatively more intense drying occurred in the southern lowlands than in the northern lowlands during the Terminal Classic period, consistent with earlier and more persistent societal decline in the south. Our results also indicate a period of substantial drying in the southern Maya Lowlands from ∼200 C.E. to 500 C.E., during the Terminal Preclassic and Early Classic periods. Plant wax carbon isotope records indicate a decline in C4 plants in both lake catchments during the Early Classic period, interpreted to reflect a shift from extensive agriculture to intensive, water-conservative maize cultivation that was motivated by a drying climate. Our results imply that agricultural adaptations developed in response to earlier droughts were initially successful, but failed under the more severe droughts of the Terminal Classic period.

Effect of processing systems on the quality and stability of Chemlali olive oils.

The present work has been carried out to ascertain the influence of different processing systems employed in olive process on the chemical composition, quality and stability of three Chemlali olive oils. Among these oils, two were classified as extra-virgin olive oils and the third named repassed olive oil was classified as an ordinary virgin olive oil. The analysis of the effect of the processing (two- and three-phases) on the analytical determinations values, revealed statistically significant differences (p<0.05) in some parameters, mainly in oxidative stability, antioxidant activity, total waxes, total phenols, o-diphenols and α-tocopherol contents as well as phenolic composition. The phenolic composition values were higher in the extra-virgin olive oil obtained from the two-phase system than in that obtained from the three-phase processing because it does not require the addition of water to the olive paste. Nevertheless, they were lower in the ordinary virgin olive oil (repassed olive oil) which was obtained by introducing hot water to the wet residues into the centrifugation processing at two-phases, than those in the extra-virgin olive oils obtained from the two- and three-phase processing.