Kontinuierliche Mengen- und Dichtemessung von Stärkesuspensionen

Continuous Volume and Density Measurement of Starch Suspensions. This contribution deals with continuous volume and density measurements of starch suspensions. After a foreword as introduction and presentation of the problem range the inductive volume, radiometric density and gravimetric density measurements are discussed in three different chapters. In each of these chapters first the principal of the measuring system as well as the construction and operation of the measurement unit tested are described. A detailed report on the performance of the tests finally is followed by the discussion of the results which can be summarized as follows: Apart from restrictions and difficulties demonstrated in detail no apparatus trouble did occur. Refered to the obtained test data all measurement units are to be evaluated as absolutely suitable for continuous volume and density measurements as absolute measurements. With regard to the inductive volume measurements the sediments amounted on the average less than 1,0% thus remaining within the measuring tolerance of ±1,25% as indicated by the manufacturing company. Also the radiometric density measurements on the average resulted in maximum divergences of only ±0,10% with the radiometric density measurement unit I and of likewise only ±0,15% with the radiometric density measurement unit II, thus again remaining within the measuring tolerance of ±1,0% of the measuring result as given by the two manufacturers. The observed divergences of the gravimetric density measurements as result of sediments in the measuring section stayed after one-week test period within the error limit of ±1,0% as limited by the manufacturing company. The determined measuring accuracy, therefore also was fully sufficient provided that the measuring divice was carefully rinsed once a week.     

Inactivation Kinetics of Enzymes by Using Continuous Treatment with Microbubbles of Supercritical Carbon Dioxide

ABSTRACT Enzyme inactivation using a new apparatus for continuous treatment with microbubbles supercritical carbon dioxide (SC-CO₂) was investigated. D value of a-amylase (5.0±1.2 min) subjected to microbubbles of SC-CO₂ treatment (microbubbles-SCT) at 35 °C, 30 MPa was lower than that (227 ± 15.9 min) subjected to heat treatment (HT) at 70 °C. D value of acid protease was reduced by microbubbles-SCT at 50 °C, 30 MPa (15.4 ± 4.1 min), compared to HT at 50 °C (233 ± 15.2 min). The activation energy for the inactivation of acid protease (135 ± 8.3 kJ mol^-1) by microbubbles-SCT was 1 half of that (259 ± 9.0 kJ mol^-1) by HT. These results indicated that continuous treatment with microbubbles of SC-CO₂ was effective for enzyme inactivation.     

Dimensional changes of extracted and non-extracted small wood specimens of black locust ( Robinia pseudoacacia L.)

From straight grained heartwood of black locust (Robinia pseudoacacia L.), specimens, 3 cm×3 cm in cross section and 0.5 mm (or 10 mm) in axial direction, were cut and used for the determination of dimensional changes and the rate of tangential swelling. Mean radial, tangential and axial shrinkage was 5.30%, 6.67% and 0.16%, respectively, while the coefficient of anisotropy was 1.26. Half of the specimens for the determination of the rate of tangential swelling were extracted for 48 h with distilled hot water. The tangential dimensional change and the time taken to attain half maximum swelling in air-dry and oven-dry specimens were assessed according to a common technique. Extractive removal resulted in an increase of the total magnitude of tangential swelling in both air-dry and oven-dry specimens. However, no significant differences in time taken to attain half maximum swelling between air-dry and oven-dry specimens were observed after extraction. The rate of tangential swelling was lower in air-dry specimens than in oven-dry specimens after 30 min of immersion in water when were non-extracted and after 5 min of immersion in water when were extracted. Extracted air-dry specimens had a greater rate of tangential swelling than non-extracted air-dry specimens and the same occurred for oven-dry specimens. Extraction resulted in a higher diffusion coefficient for air-dry specimens. The diffusion coefficient calculated for non-extracted air-dry specimens (0.901×10^–4 cm²/min) showed that black locust is a difficult species to impregnate.     

A simple method for determining the shear modulus of food dispersions and gels

The application of a simple commercially available apparatus to the measurement of the dynamic shear modulus for viscoelastic food dispersions and gels is described. For vibrant gels the shear modulus can be determined to a precision of ±5% in the range 50 to 5 × 10⁵ Nm^?2 and the value is independent of the frequency as the gel behaves like a simple elastic solid. The measurement causes minimal mechanical disturbance to a gel or dispersion and is thus ideally suited for monitoring weak network structures. With weak or “dead” gels, or pastes, the dynamic modulus at just one frequency, 200 Hz, is found.     

Transmembrane Mass Transfer in Carrot Protoplasts during Osmotic Treatment

Minimized experiments with Confocal Scanning Laser Microscopy were used to describe mass transfer of isolated carrot protoplasts from at the usual conditions of the Osmotic Treatments (OT). Carrot protoplasts during OT with 30, 40 and 50% sucrose solutions were monitored. The ratio of cellular volume before and after OT with 30, 40 and 50% sucrose solutions was 0.86 ± 0.12, 0.41 ± 0.04 and 0.17 ± 0.02, respectively. Trans‐membrane water flux was determined from cellular shrinkage, and the coefficient for water membrane permeability was (5.2 ± 0.9) 10^‐6 mol²/Jm²s. To describe water transport in protoplasts at transient conditions, the diffusional approach was used. The effective water diffusivity during OT with 50% sucrose solutions was in the (0.8‐1.8) 10^‐12 m²/s range.     

Measurement of Gelpoint Temperature and Modulus of Pectin Gels

Methods which permit the measurement of gelpoint (setting) temperature (T_gel) and rigidity modulus (G) of pectin gels were improved. Gel development on cooling was determined with an oscillatory pressure testing device capable of detecting a modulus as low as 3 Pa and strain values no greater than 5∞10^?3. Sample was set in a glass “U” tube during pressure oscillatory assay for T_gel determination, and transferred after gelling in the same tube for G modulus determination with modified Saunders-Ward apparatus. Results confirmed rheological behavior reported for these kinds of gels and compared favorably with small amplitude oscillatory measurements performed with a stress controlled rheometer using cone and plate (4°, dia = 4 cm) geometry at different frequencies (0.5 to 1.5 Hz) and cooling rates (1 to 3°C/min).     

Effect of osmotic stress on microstructure and mass transfer in onion and strawberry tissue

We investigated the structural changes in onion epidermis and strawberry cortex tissue due to osmotic stress during osmotic treatment (OT) with sucrose solutions of concentrations ranging from 300 to 600 g kg^?1. We used miniaturised experiments with confocal scanning laser microscopy (CSLM) to monitor microstructural changes—cellular shrinkage and viability—during OT. The overall cellular shrinkage of these plant tissues was not significantly different under the same conditions of osmotic stress. For onion epidermis we determined the transmembrane water flux from the cellular shrinkage and found that the coefficient of water membrane permeability was (1.0 ± 0.39) × 10^?6 mol² J^?1 m^?2 s^?1. Osmotic stress did not affect the cellular viability of onion epidermis but significantly reduced the viability of protoplasts of strawberry in the whole range of solution concentrations. We used Fick's unsteady state second‐order diffusion equation to describe cellular water transport under transient conditions. The pseudo‐diffusional approximation led to water diffusivity values in the range (3–10) × 10^?12 m² s^?1 for both onion epidermis and strawberry cortex tissue. The concentration of the solution did not significantly affect the values of effective water diffusivity, which indicated the primary role of the plasma membrane during the initial stages of OT. Copyright © 2003 Society of Chemical Industry     

Distortion of Norway spruce timber Part 1. Variation of relevant wood properties Part 1. Variation of relevant wood properties

) trees from one fast-grown and one slow-grown stand in southern Sweden. From the trees 240 studs (45 × 70 × 2500 mm) were taken for measurement of distortion. Wood properties were measured on small specimens (13 × 13 × 200 mm) cut from the studs. Spiral grain angle was found to vary from approximately +3° (left-handed) close to pith to zero 150 mm from pith with a strong individual variation. The material from the fast-grown stand had a larger spiral grain angle compared with the slow-grown material. Spiral grain was poorly correlated to other parameters. Presence of knots had a substantial influence on longitudinal shrinkage (α_l) measurements. Specimens with large knots (KAR > 33%) had almost 100% higher longitudinal shrinkage than specimens without knots. It should be pointed out, however, that measuring shrinkage in small specimens containing even small knots can create a problem with regards to the obtained results, especially results of α_l. It was found that presence of compression wood in several growth rings more than doubled the longitudinal shrinkage. For the radial and tangential direction the presence of compression wood decreased shrinkage with about 30%. The ratio between tangential and longitudinal shrinkage was 49 for normal wood whereas for compression wood the ratio was 13. These results confirm the theory that the microfibril angle governs shrinkage. Longitudinal shrinkage decreased slightly with increased distance from pith whereas radial and tangential shrinkage did not display any substantial radial variation. The fast-grown material had generally a higher longitudinal shrinkage and lower transverse shrinkage than the material from the slow-grown stand. About 50% of the variation in longitudinal shrinkage was explained by radial position, density and ring width. Density and ring width did explain 60% of the variation in radial shrinkage but only 30% of the variation in tangential shrinkage.     

Effect of Process Parameters on Work Index, Milling Efficiency and Some Technological Properties of Yam Flour Using Attrition Mill

The effect of process parameters on work index, efficiency of milling, bulk density, swelling capacity and water absorption capacity of yam flour using attrition mill was studied. Independent variables were: moisture content (8, 12, 16, 20 and 24 % w.b.), speed (288, 346, 432, 576 and 864 rpm) and inlet opening (1,300, 2,600, 3,900, 5,200 and 6,500 mm²). The responses were work index, milling efficiency, bulk density, water absorption and swelling capacities of the flour. Work indexes for milling yam flour, meal and grit were found to be 0.25?±?0.13, 0.49?±?0.14 and 1.8?±?0.56, respectively. Flour fraction, bulk density, water absorption capacity and swelling capacity ranged from 42.2 to 56.6 %, 0.54 to 0.66 g/m³, 200 to 400 % and 13 to 23 ml, respectively. The treatments were found to influence the responses significantly (p?<?0.05). Optimum process condition was achieved at 12 % moisture content of feed, 506 rpm shaft speed and 5,200 mm² feed opening giving 19.1 % grit, 23.6 % meal and 54.2 % flour. The desirability of the optimisation process was 0.78. Validation of predicted optimal moisture content, worm shaft speed and feed inlet opening gave errors of 19, 14.4 and 6.1 % for grit, meal and flour, respectively.     

Simultaneous measurement of oxygen and carbon dioxide diffusivities in pear fruit tissue using optical sensors

Gas diffusion properties of pear tissue are important in relation to gas exchange of the fruit with its environment during storage. In this contribution, a set‐up for measuring tissue diffusivity using fluorescent optical probes was developed. O₂ and CO₂ diffusivities were determined simultaneously based on a finite element model describing simultaneous O₂ and CO₂ gas transport as well as respiration in the tissue. The effect of variations on the diffusion set‐up conditions such as the volume of the measurement chamber and thickness of the sample on the accuracy of the estimated diffusivities was investigated using a sensitivity analysis on simulated data. The optical sensors produced good informative O₂ and CO₂ partial pressure versus time profiles. The average O₂ and CO₂ diffusivity of pear cortex tissue was (2.56 ± 0.48) × 10^?10 m² s^?1 and (3.8 ± 1.1) × 10^?9 m² s^?1, respectively. The coefficient of variation of diffusivity of O₂ and CO₂ in pear tissue due to bias, variation of the sample thickness and volume of the measurement chamber was 2.0–2.3% and 2.1–2.4% for a measurement chamber volume between 7.5 and 15 mL and a tissue thickness of 1–2.5 mm, respectively. The variability of estimated diffusivities due to measurement errors was eight times smaller than the biological variability. Copyright © 2007 Society of Chemical Industry     

Laboratory apparatuses measuring 3D displacement fields involved in distortion of commercial size wood products due to moisture content change.

Two apparatuses developed in our laboratory and based on the same principle are described and tested. They semi-automatically acquire the 3D location of dots making up a network at the surface of wood-products in order to measure the resulting displacement field. The location of each dot is achieved by means of an image analyser coupled with a 2-axis robot to determine the location of the barycentre in the corresponding plan. The third co-ordinate is obtained through a displacement sensor. The accuracy of each device is studied and discussed through the analysis of repeated measurements performed on three products such as: small oak plank (150×120×27 mm), commercial size oak plank (1930×150×30 mm), 3ply cross-laminated douglas fir panel (390×390×6 mm). Two kinds of testing are performed: A-Test without motion of the sample to assess the accuracy in dot detection, and B-Test corresponding to a real measurement where no variation of moisture content has occurred and which theoretically leads to displacements equal to zero.     

The effect of pregnancy on tear osmolarity

ObjectiveTo examine the effect of pregnancy on the lacrimal system through tear osmolarity measurement and the Schirmer test.Material and MethodThe study consisted of two groups of 30 women between 20 and 40 years old; the women in the study group were in their first trimester of pregnancy, and the women in the control group were not pregnant and did not have any diseases other than refractive error. Tear osmolarity measurement with the TearLab osmolarity system and tear function test Schirmer 1 were carried out on one, randomly chosen eye of each participant. The pregnant women’s measurements were repeated on the same eye in their last trimester.ResultsThe study group’s first trimester tear osmolarity measurement was 304.9 ± 8.0 mOsm/L, while their last trimester tear osmolarity measurement was 300.2 ± 7.1mOsm/L and the control group’s was 306.3 ± 6.2 mOsm/L. There was a statistical difference between the study group’s first and last trimester results and between the study group’s last trimester and the control group’s results (p < 0.05). The Schirmer test results were 18.1 ± 6.3 mm for the study group’s first trimester, 16.6 ± 6.9 mm for the last trimester and 21.3 ± 9.0 mm for the control group. There was a statistically significant difference between the study group’s last trimester results and the control group’s Schirmer test results (p < 0.05).ConclusionBoth the tear osmolarity values and Schirmer values were found to decrease significantly towards the end of pregnancy. These results suggest that decrease in both test results may play a protective role in the ocular surface during pregnancy.     

Modeling some thermal and physical characteristics of terebinth fruit under semi industrial continuous drying

In this research, the effect of different drying conditions on thermal and physical properties of terebinth fruit was studied. Experiments were conducted with a semi industrial continuous dryer in air temperature levels of 45, 60, 75 °C, air velocity levels of 1, 1.5 and 2 m/s and belt linear speeds of 2.5, 6.5, 10.5 mm/s. Results showed that the Midilli model had the best performance in predicting the moisture ratio. Effective moisture diffusivity of terebinth fruit during experiments was 6.48 × 10^?11–2.34 × 10^?10 m²/s achieved. Activation energy of the samples between 25.45 and 35.16 kJ/mol was obtained. The highest and lowest values of specific energy consumption 65.2 and 10.5 GJ/kg were calculated. Maximum value of shrinkage (16.70 %) was calculated at air temperatures of 75 °C and minimum value (12.34 %) was achieved at air temperature of 45 °C. After drying, total color difference was increased, and hue angle and chroma were decreased. Rupture force for dried terebinth between 80.15 and 112.68 N mm were calculated.     

Chocolate Swelling during Storage Caused by Fat or Moisture Migration

Abstract: Quantification of swelling in dark chocolate subjected to fat or moisture migration was conducted using a new method based on confocal chromatic displacement sensor. The nondestructive method allowed for the height profile of dark chocolate samples to be scanned with a sensitivity of ± 2.8 μm. By performing multiple scans on each sample prior to and after being subjected to fat or moisture migration, the induced swelling could be quantified. Applying the new method on confectionery systems revealed that fat and moisture migration generate different swelling behavior/kinetics in dark chocolate during storage. Moisture migration resulted in a rapid swelling once a water activity of 0.8 was reached in the chocolate, probably by interaction and absorption of moisture by the particulate solids. Fat migration also affected the swelling behavior in chocolate, possibly by inducing phase transitions in the continuous cocoa butter phase. Migrating fat also proved to induce a more pronounced swelling than the same amount of absorbed moisture which further consolidated that the observed swelling caused by fat or moisture migration is a result of significant different mechanisms.     

The Dyeing of Polyolefin Fibers in Supercritical Carbon Dioxide. Part I: Thermo-mechanical Properties of Polyolefin Fibers after Treatment in CO2 under Dyeing Conditions

The viscoelastic properties of gel-spun polyethylene (PE) and polypropylene (PP) fibers after treatment in supercritical CO₂, at 280 bar were examined to determine the optimum conditions for dyeing without causing fiber damage. Above 100°C, a greater amount of shrinkage, mainly of PP fiber, is observed in CO₂, than in air at 1 bar. Under isothermal conditions at 100°C, pressure-dependent on-line measurements of a PP-fiber monofli up to 280 bar show that shrinkage becomes very considerable at low pressures of only 10 bar. In comparison with isobaric conditions at 280 bar, shrinkage starts at temperatures above 60°C and is greatest between 90 and 100°C. In both cases, the degree of shrinkage is 11–12%. The value of F._max on the stress—strain diagrams of all fibers tested is not influenced by the treatment in CO₂, up to 120°C. However, the elongation increases only for polyolefins with a lower degree of crystallinity to the extent of about 15% for the PP monofil and 13% for the LM-PE fiber. Furthermore, CO₂, is able to penetrate into the hydrophobic PE and PP fibers and acts as a quasi-impurity, reducing the melting point (mp) of LM-PE fibers by between 5 and 7^°C and that of PP monofli by 9 and 22°C at 50 and 280 bar, respectively. This was observed by differential-dynamic-heat-flow calorimetric measurements in CO₂. The decrease in mp of the highly crystalline HM-PE fiber is only 2°C because the diffusion of CO₂ into the fiber is extremely slow.     

Dimensional changes of extracted and non-extracted small wood specimens of black locust (<Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> L.)

From straight grained heartwood of black locust (Robinia pseudoacacia L.), specimens, 3 cm×3 cm in cross section and 0.5 mm (or 10 mm) in axial direction, were cut and used for the determination of dimensional changes and the rate of tangential swelling. Mean radial, tangential and axial shrinkage was 5.30%, 6.67% and 0.16%, respectively, while the coefficient of anisotropy was 1.26. Half of the specimens for the determination of the rate of tangential swelling were extracted for 48 h with distilled hot water. The tangential dimensional change and the time taken to attain half maximum swelling in air-dry and oven-dry specimens were assessed according to a common technique. Extractive removal resulted in an increase of the total magnitude of tangential swelling in both air-dry and oven-dry specimens. However, no significant differences in time taken to attain half maximum swelling between air-dry and oven-dry specimens were observed after extraction. The rate of tangential swelling was lower in air-dry specimens than in oven-dry specimens after 30 min of immersion in water when were non-extracted and after 5 min of immersion in water when were extracted. Extracted air-dry specimens had a greater rate of tangential swelling than non-extracted air-dry specimens and the same occurred for oven-dry specimens. Extraction resulted in a higher diffusion coefficient for air-dry specimens. The diffusion coefficient calculated for non-extracted air-dry specimens (0.901×10^–4 cm²/min) showed that black locust is a difficult species to impregnate.

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Dimensionsveränderungen extrahierter und nicht-extrahierter kleiner Holzproben von Robinie (Robinia pseudoacacia L.)

Zusammenfassung Von Robinienkernholz (Robinia pseudoacacia L.) mit senkrecht verlaufenden Fasern, wurden Proben 3 cm×3 cm im Querschnitt und 0,5 mm (oder 10 mm) in axialer Richtung geschnitten und zur Bestimmung dimensionaler Veränderungen und der tangentialen Quellenrate verwendet. Die mittlere radiale, tangentiale und axiale Schrumpfung betrug 5,30%. 6,67% und 0,16%, wobei der Anisotropie-Koeffizient 1,26 betrug. Die Hälfte der Proben zur Bestimmung der radialen Quellung wurde 48 Stunden lang mit heißem destillierten Wasser extrahiert. Die tangentiale dimensionale Veränderung und die benötigte Zeit, um ein halb-maximales Quellen bei Luft- und Ofentrocknung zu erreichen wurde gemäß einer bekannten Methode geschätzt. Die Entfernung der Extraktstoffe führte zu einer Zunahme der Gesamtgröße der tangentiellen Schwellung sowohl der luft- als auch der ofengetrockneten Proben. Es wurden jedoch keine signifikanten Unterschiede in der Zeit nach der Extraktion beobachtet, die benötigt wurde, um die halb-maximale Schwellung zwischen luft- und ofengetrockneten Proben zu erreichen. Die Rate der tangentiellen Schwellung war bei luftgetrockneten Proben niedriger als bei ofengetrockneten Proben nach 30-minütigem Eintauchen in Wasser. Extrahierte luftgetrocknete Proben hatten eine größere Rate tangentieller Schwellung als nicht-extrahierte luftgetrocknete Proben, das gleiche gilt für ofengetrocknete Proben. Die Extraktion führte zu einem höheren Diffusionskoeffizienten bei luftgetrockneten Proben. Der berechnete Diffusionskoeffizient von nicht-extrahierten luftgetrockneten Proben (0,901×10^–4 cm²/min) zeigte, dass Robinien eine schwierig zu imprägnierende Spezies sind.

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Part of Doctoral thesis of Mr. Stergios Adamopoulos titled: "Anatomical characteristics and technical properties of black locust wood (Robinia pseudoacacia L.)". Aristotelian University, Thessaloniki, 2001.     

The relationship between anogenital distance and fertility,and genome-wide associations for anogenital distance in Irish Holstein-Friesian cows

The evaluation of anogenital distance (AGD), the distance from the center of the anus to base of the clitoris, as a potential fertility trait for genetic selection in dairy cows has generated recent interest. The objectives of this cross-sectional observational study were to (1) characterize the distribution and variability of AGD, (2) determine factors associated with AGD, (3) estimate heritability for AGD, (4) identify single nucleotide polymorphisms (SNP) associated with phenotypic variation of AGD, and (5) validate the relationship between categories of AGD and fertility in Irish Holstein-Friesian cows. Anogenital distance was measured using digital calipers in 1,180 Holstein cows (mean ± standard deviation: 225 ± 79 d in milk) from 10 dairy herds located in Munster, Ireland. In addition, age (yr), weight (kg), height at hip (cm), and body condition score (BCS) at the time of AGD measurement were determined in a subset of 281 cows. Genotype information available from 908 cows was subsequently imputed to the Illumina Bovine High Density BeadChip (Illumina Inc., San Diego, CA) for genome-wide association analysis of phenotypic variation in AGD. Overall, AGD had a normal distribution and high variability (mean ± standard deviation; 119.2 ± 11.6 mm). Anogenital distance was weakly but positively associated with cow age, hip height, and body weight, and negatively associated with BCS; the phenotypic variation in AGD that was explainable by these variables was small (coefficient of determination; R² = 0.09, 0.06, 0.10, and 0.02, respectively). The estimated heritability for AGD was 0.37 (standard error of mean ± 0.08). Six SNP of suggestive significance were identified on Bos taurus autosomes 6, 15, 20, and 26; however, none of these SNP was related to previously identified candidate genes for fertility. Cows were categorized into quartiles (Q1; 86 to 111 mm; n = 311, Q2; 112 to 120 mm; n = 330; Q3; 121 to 127 mm; n = 265, and Q4; 128 to 160 mm; n = 274) based on AGD and the association with reproductive outcomes examined (21-d submission rate, pregnancy to first AI, pregnancy rate within 21, 42 and 84-d after the farm mating start date, and number of times bred). None of the reproductive variables differed significantly between AGD categories. In summary, despite identification of high variability and moderate heritability for AGD in Irish Holstein-Friesian cows, reproductive outcomes did not differ between categories of AGD. This latter result differs from our previous finding of an inverse relationship between AGD and pregnancy outcomes in first- and second-parity Canadian Holstein cows, emphasizing the need to test and validate this new phenotype in diverse cow populations.     

Emissions of volatile organic compounds originating from UK livestock agriculture

In this paper we estimate the quantity of non‐methane volatile organic compounds (NMVOCs) emitted from UK livestock. The final estimate is derived from published values and from direct measurements of NMVOC emissions from dairy cattle slurry and laying hen manure. Emission rates of NMVOCs were determined for fresh dairy cattle slurry and laying hen manure using a 40 m³ emissions chamber. Dimethyl sulphides dominated emissions from laying hen manure at 753 ± 263 g m^?3 day^?1. Emissions from dairy cattle slurry were dominated by volatile fatty acids (C₂? C₅, 6.3 ± 3.1 g m^?3 day^?1) and phenols (2.4 ± 1.2 g m^?3 day^?1). Many of these NMVOCs are decomposition products from protein sources from which ammonia is also a by‐product. There is a close association between ammonia and NMVOC production from manure, and on this basis we estimated the annual NMVOC emissions from UK livestock as 165 ± 56 kt for 2002. These emissions compare to those from the larger industrial and transport sectors and exceed the 50–100 kt C year^?1 currently determined as originating from biogenic sources including agriculture. These findings have implications for air quality, and these NMVOCs may affect the cleansing capacity of the troposphere. Copyright © 2004 Society of Chemical Industry     

Lemon (Citrus limon, Burm.f.) essential oil enhances the trans-epidermal release of lipid-(A, E) and water-(B6, C) soluble vitamins from topical emulsions in reconstructed human epidermis

Topical bioavailability of lipid‐ and water‐soluble vitamins is a critical issue for protecting or anti‐ageing formulations. Using 17‐day‐old SkinEthic^® reconstructed human epidermis, we investigated (at 34°C) the role of lemon EO in enhancing the penetration of α‐tocopherol (E) and retinyl acetate (A), pyridoxine (B₆) and ascorbic acid (C), released from O/W or W/O emulsions. D‐limonene, α‐pinene and p‐cymene (65.9, 2.2 and 0.5%w/w of the oil) had skin permeability coefficients Ps (10^?3 cm h^?1) of 0.56 ± 0.03 (or 0.73 ± 0.02), 0.72 ± 0.05 (or 0.98 ± 0.05) and 0.84 ± 0.04 (or 1.14 ± 0.04), respectively, when incorporated in a W/O (or O/W) emulsion. Vitamins B6, C and A had Ps values of (3.0 ± 0.4) × 10^?3, (7.9 ± 0.6) × 10^?3 and (0.37 ± 0.02) × 10^?5 cm h^?1, respectively, and their flux through the skin was enhanced by a factor of 4.1, 3.4 and 5.8, respectively, in the presence of lemon EO. The penetration of vitamin E was nine‐fold enhanced. Lemon EO produced only reversible modification of TEWL, and it is a safe and effective penetration enhancer for topical administration of lipid‐ and water‐soluble vitamins.     

‘Best before period once opened’ for honey samples from oceanic climates on the basis of their acidity types

Stability of food is of particular interest, as we should know the period for which a given food maintains its original quality. Acidity is a very important parameter as regards honey quality control. In this study we analysed a possible ‘best before period once opened’, regarding the evolution of acidity in honey throughout 30 months in samples from regions with oceanic climates. The study was carried out at room temperature (between 15 and 25 °C) by analysing all samples in duplicate each 5 months. We also researched the possible influence of induced granulation on the acidity evolution of honey samples, observing that as the analysis of variance showed significant differences at P‐value <0.05, this process had a significant influence on free acid and total acidity. All samples fulfilled the European Regulations regarding free acid, because no honey sample showed a free acid value higher than the limit of 50 meq kg^?1. Nevertheless, all honey samples suffered a continuous decrease of pH from 20 months on (averages: from 4.1 ± 0.25 at 20 months to 4.0 ± 0.23 at 30 months), and a continuous increase of both free acid (averages: from 27.6 ± 6.22 meq kg^?1 at 20 months to 33.5 ± 6.44 meq kg^?1 at 30 months) and total acidity (averages: from 42.5 ± 7.60 meq kg^?1 at 20 months to 44.7 ± 7.60 meq kg^?1 at 30 months). On the basis of acidity types, 20 months should be considered the ‘best before period once opened’ for honey from regions with oceanic climates.