Beet Slices Research Articles

Hydrogen-Rich Water Can Restrict the Formation of Biogenic Amines in Red Beet Pickles

Fermented foods are considered the main sources of biogenic amines (BAs) in the human diet while lactic acid bacteria (LAB) are the main producers of BAs. Normal water (NW) and hydrogen-rich water (HRW) were used for preparing red beet pickles, i.e., NWP and HRWP, respectively. The formation of BAs, i.e., aromatic amines (tyramine, 2-phenylethylamine), heterocyclic amines (histamine, tryptamine), and aliphatic di-amines (putrescine), was analyzed in both beet slices and brine of NWPs and HRWPs throughout the fermentation stages. Significant differences in redox value (Eh7) between NWP and HRWP brine samples were noticed during the first and last fermentation stages with lower values found for HRWPs. Total mesophilic aerobic bacteria (TMAB), yeast–mold, and LAB counts were higher for HRWPs than NWPs for all fermentation stages. Throughout fermentation stages, the levels of all BAs were lower in HRWPs than those of NWPs, and their levels in brines were higher than those of beets. At the end of fermentation, the levels (mg/kg) of BAs in NWPs and HRWPs were, respectively: tyramine, 72.76 and 61.74 (beet) and 113.49 and 92.67 (brine), 2-phenylethylamine, 48.00 and 40.00 (beet) and 58.01 and 50.19 (brine), histamine, 67.89 and 49.12 (beet) and 91.74 and 70.92 (brine), tryptamine, 93.14 and 77.23 (beet) and 119.00 and 93.11 (brine), putrescine, 81.11 and 63.56 (beet) and 106.75 and 85.93 (brine). Levels of BAs decreased by (%): 15.15 and 18.35 (tyramine), 16.67 and 13.44 (2-phenylethylamine), 27.65 and 22.7 (histamine), 17.09 and 21.76 (tryptamine), and 21.64 and 19.5 (putrescine) for beet and brine, respectively, when HRW was used in pickle preparation instead of NW. The results of this study suggest that the best method for limiting the formation of BAs in pickles is to use HRW in the fermentation phase then replace the fermentation medium with a new acidified and brined HRW followed by a pasteurization process.

Influência da espessura na cinética de secagem de fatias de beterraba

O presente trabalho tem como objetivo avaliar a influência da espessura na cinética de secagem de fatias de beterraba e ajustar modelos matemáticos (empíricos e difusivos) aos dados experimentais. As beterrabas foram fatiadas em três diferentes espessuras (4; 6 e 8 mm) e a cinética de secagem foi realizada em estufa de circulção de ar com velocidade do ar de 1,5 m.s-1, na temperatura de 60 ºC. Os modelos matemáticos empíricos (Lewis, Page e Handerson e Pabis) e difusivos considerando a geometria de parede infinita e a condição de contorno do terceiro tipo foram ajustados aos dados experimentais. O modelo de Page apresentou como o de melhor ajuste quando comparado aos demais por apresentar valores superiores de R2 (R2 > 0,99) e valores inferiores da função qui-quadrado. A solução analítica da equação de difusão com geometria de parede infinita, apresentou aumento da difusividade e do coeficiente convectivo de transferência de calor com incremento da espessura das fatias e os baixos valores do número de biot indicam que a condição de contorno utilizada (terceiro tipo) descreveu de forma satisfatória o processo. No entanto, quando se teve aumento da espessura das fatias, menores foram as variações de umidade em seu interior no decorrer do tempo.

Evaluation of the combined effect of osmotic and Refractance Window drying on the drying kinetics, physical, and phytochemical properties of beet

The effect of osmotic dehydration (OD) with different sucrose concentrations and temperatures was studied in combination with drying by Refractance WindowTM (RW) in beet slices with thicknesses of 1 and 5 mm. The color, texture, total polyphenol content (TPC), total flavonoid content (TFC), and antioxidant capacity (AC) of the beet with OD, RW, and OD-RW combined drying were evaluated. The best results of water loss (WL) and solid gain (SG) with OD were obtained with 65% sucrose solution at 60 °C. OD partially reduced the water content of the slices, decreasing the drying time with RW at 85 °C. However, the retention of qualities such as color, texture, TPC, TFC, and AC in beet was obtained with combined drying by OD-RW at 60 °C under OD conditions of 65% sucrose at 45 °C. These conditions afforded a stable product retaining its physical and chemical properties.

Effect of the Architecture of Fiber-Optic Probes Designed for Soluble Solid Content Prediction in Intact Sugar Beet Slices.

Sugar beet is the second biggest world contributor to sugar production and the only one grown in Europe. One of the main limitations for its competitiveness is the lack of effective tools for assessing sugar content in unprocessed sugar beet roots, especially in breeding programs. In this context, a dedicated near infrared (NIR) fiber-optic probe based approach is proposed. NIR technology is widely used for the estimation of sugar content in vegetable products, while optic fibers allow a wide choice of technical properties and configurations. The objective of this research was to study the best architecture through different technical choices for the estimation of sugar content in intact sugar beet roots. NIR spectral measurements were taken on unprocessed sugar beet samples using two types of geometries, single and multiple fiber-probes. Sugar content estimates were more accurate when using multiple fiber-probes (up to R2 = 0.93) due to a lesser disruption of light specular reflection. In turn, on this configuration, the best estimations were observed for the smallest distances between emitting and collecting fibers, reducing the proportion of multiply scattered light in the spectra. Error of prediction (RPD) values of 3.95, 3.27 and 3.09 were obtained for distances between emitting and collecting fibers of 0.6, 1.2 and 1.8 µm respectively. These high RPD values highlight the good predictions capacities of the multi-fiber probes. Finally, this study contributes to a better understanding of the effects of the technical properties of optical fiber-probes on the quality of spectral models. In addition, and beyond this specificity related to sugar beet, these findings could be extended to other turbid media for quantitative optical spectroscopy and eventually to validate considered fiber-optic probe design obtained in this experimental study.

Dead end ultra-filtration of sugar beet juice expressed from cold electrically pre-treated slices: Effect of membrane polymer on fouling mechanism and permeate quality

Abstract Purification of raw sugar beet juice expressed at ambient temperature (20 °C) from pretreated sugar beet slices by pulsed electric field (E = 600 V·cm− 1, tPEF = 10 ms, T = 20 °C) was studied on the laboratory scale by dead-end ultrafiltration tests. Polyethersulfone (PES) and Regenerated Cellulose (RC) membranes with the same nominal molecular weight cut-off of 30 kDa were used. Experiments were carried out in unstirred and stirred (at rotation speed of 500 rpm) mode at constant trans-membrane pressure of 2 bar. The effects of the membrane polymer (Polyethersulfone and Regenerate Cellulose) on the filtration flux and the permeate quality were studied. In order to identify the fouling mechanism, the filtration kinetics was modeled using combined fouling models. Results showed that the filtration productivity (filtration flux) and selectivity (rejection ratio of impurities) depended on the membrane polymer. The juice filterability was better with Regenerated Cellulose (RC) membrane while the polyethersulfone (PES) membrane ensured a better retention of impurities (colorants, proteins and colloids), leading to a higher juice purity. Experimental and models data adjustment showed that combined models were preferable to investigate the fouling mechanism for both unstirred and stirred filtration. The desirable sugar purity (95–96%) of filtrate implies the potential application of a novel process (PEF treatment-cold pressing-ultrafiltration) for sugar industrial production. Industrial relevance Pre-treatment by pulsed electric field PEF allowed cold or mild extraction of sucrose from sugar beet roots. The combination of PEF and ultra-filtration allowed high yield sucrose extraction and purification with less energy consumption. Membrane fouling analysis led to better filtration producibility. The obtained data can be useful for optimization of the sucrose production with high yield in industrial extraction processes.

Several-staged alkaline pressing-soaking of electroporated sugar beet slices for minimization of sucrose loss

Abstract In this work, a new process of several-staged alkaline pressing-soaking of electroporated sugar beet slices is proposed and analyzed to minimize the sucrose loss. For this purpose, sugar beet roots were first sliced and electroporated by pulsed electric field (PEF) at ambient temperature with electric field strength of E = 600 V/cm and effective duration of t PEF = 10 ms. The PEF treated slices were then subjected to a double pressing with an intermediate lime milk soaking (using 0.6 g CaO/100 g fresh slices). The obtained limed press-cake was again pressed one or two times with an intermediate water soaking to recover the residual sucrose. The degree of the first pressing U was fixed at 50 or 75%, the expression pressure was varied from 1 to 50 bar, the soaking degree of lime milk α was varied from 0 to 20% and the soaking degree of water β was fixed at 5 or 10%. The total yield of solutes in an optimized four-staged pressing-soaking was 99.53%, the sucrose loss in pulp was 0.23% and the dryness of pulp was 39%. The quality of mixed expressed juice was better that that of the traditional diffusion juice obtained by hot water extraction. Expressed juice was more concentrated (18 vs. 14.5%), had higher purity (93.16 vs. 91.62%), and lower coloration (2619 vs. 9842 IU) than the juice obtained by hot water extraction. The proposed process presents major advantages including cold processing, high pulp dryness, lower quantity of water addition and shorter extraction duration. It seems to be very promising for energy save, environmental protection and bioeconomy in future sugar beet industry. Industrial relevance Conventional sugar beet extraction by hot water is energy costly and produces impure extracts of high coloration. Application of pulsed electric field and following pressing of electroporated sugar beet slices improve juice quality and decrease energy consumption. However, the sucrose losses in pulp remain high. Staged alkaline pressing-soaking of electroporated sugar beet slices investigated and optimized in this study permits minimizing of sucrose losses in pulp, improvement of juice quality and production of the pulp of high dryness.

Predict Compositions and Mechanical Properties of Sugar Beet Using Hyperspectral Scattering

Sucrose, soluble solids, and moisture content and mechanical properties are important quality/property attributes of sugar beet. In this study, hyperspectral scattering images for the spectral region of 500–1000 nm were acquired, from which relative mean spectra were calculated. Prediction models were developed using partial least squares regression for both full spectra and selected wavelengths. The results showed that using relative mean spectra gave good predictions for the moisture, soluble solids, and sucrose content of beet slices with the correlations of 0.75–0.88 and the standard errors of prediction of 0.95–1.08 based on full-spectrum partial least squares regression (PLSR) models. PLSR models using wavelength selection with the uninformative variable elimination (UVE) method produced similar prediction accuracy. However, both modeling approaches gave poor predictions for the mechanical properties of beets with the correlation values of 0.46–0.63. The research demonstrated the potential of hyperspectral scattering imaging for measuring quality attributes of sugar beet.

Captures ofProtaphorura fimata(Collembola: Poduromorpha: Onychiuridae) on Beet and Potato Baits in the Salinas Valley of California

Abstract Protaphorura fimata Gisin (Collembola: Poduromorpha: Onychiuridae) feeds on the germinating seeds of lettuce (Lactuca sativa L.), causing severe stand losses in the northern Salinas Valley of California. Because there is no grower-friendly tool available to monitor P. fimata in the commercial lettuce fields to guide management decisions, we examined the potential utility of potato slices (Solanum tuberosum L.), typically used to monitor garden symphylan, Scutigerella immaculata Newport, and beet slices (Beta vulgaris L.) as baits for P. fimata capture and compared them with P. fimata extracted from the soil using the Berlese funnel method. Results suggest that both potato and beet slices were attractive to P. fimata as they captured greater numbers of P. fimata when deployed in the soil than were extracted using a Berlese funnel. Between beet and potato, beet slices captured significantly greater numbers of P. fimata than potato slices in both years. In addition, two experiments were conducted t...

Measurement of moisture, soluble solids, sucrose content and mechanical properties in sugar beet using portable visible and near-infrared spectroscopy

Visible and near-infrared spectroscopy, coupled with partial least squares regression, was used to predict the moisture, soluble solids and sucrose content and mechanical properties of sugar beet. Interactance spectra were acquired from both intact and sliced beets, using two portable spectrometers covering the spectral regions of 400–1100nm and 900–1600nm, respectively. Both visible and short-wave near-infrared (400–1100nm) and near-infrared (900–1600nm) spectrometers gave excellent predictions for the moisture, soluble solids and sucrose content of beet slices with the correlations (rp) of 0.89–0.95 and the standard errors of prediction (SEP) of 0.60–0.85. Lower prediction accuracies were obtained for intact beets, with the rp values of 0.75–0.85 and the SEPs of 0.88–1.23. However, the two spectrometers showed a poor ability of predicting the compressive mechanical properties (i.e., maximum force, area and the slope for the force/displacement curve) of both beet slices and intact beets. Using simple correlation analysis, we also identified wavelengths that had strong correlation with the measured compositions of sugar beets. The portable visible and near-infrared spectrometry is potentially useful for rapid assessment of the moisture, soluble solids and sucrose content of sugar beet at harvest and during postharvest handling and processing.

Determination of sucrose content in sugar beet by portable visible and near-infrared spectroscopy

Visible and near-infrared spectra in interactance mode were acquired for intact and sliced beet samples, using two portable spectrometers for the spectral regions of 400–1100nm and 900–1600nm, respectively. Sucrose prediction models for intact and sliced beets were developed and then validated. The spectrometer for 400–1100nm was able to predict the sucrose content with correlations of prediction (rp) of 0.80 and 0.88 and standard errors of prediction (SEPs) of 0.89% and 0.70%, for intact beets and beet slices, respectively. The spectrometer for 900–1600nm had rp values of 0.74 and 0.88 and SEPs of 1.02% and 0.69% for intact beets and beet slices. These results showed the feasibility of using the portable spectrometer to predict the sucrose content of beet slices. Using simple correlation analysis, the study also identified important wavelengths that had strong correlation with the sucrose content.

Performance Enhancement of Sugar Mill by Alternate Cooling System for Condenser

Agro industry plays a crucial role in the industrialization process of developing countries. Sugar industry is second largest agro industry in the world. In sugar manufacturing plants there are various processes for production of sugar i.e. extraction of juice, clarification, evaporation, concentration of juice, forming and separating crystals etc. These processes consumed energies in the form of mechanical energy, electrical energy and heat energy. So there are various sources of heat in sugar factory i.e. heat from hot flue gasses, hot water from evaporative body and boiler blow down. The large amount of heat passes from various devices of sugar factory causes decrease in the efficiency of sugar plants, and also increase the Global Warming which is very dangerous for our environment. The present cooling system for condenser is inappropriate & hence decrease vacuum in evaporators and pans. This will increase the boiling point temperature of juice. The proposed cooling system gives solution of both problems. The most important source of heat i.e. hot flue gases are use to run absorption chiller. The absorption chiller gives better cooling system for condenser. There will be improvement in condensation of vapour in condenser which will cause increase vacuum in evaporators and pans thereby reducing boiling point temperature of juice. This reduced boiling point temperature of juice requires less amount of steam for boiling, ultimately saving of bagasse and fuel economy can be attained. Thus this arrangement can be treated as the efficient method of utilization of heat for cooling condenser water in sugar factory thus saving further depletion of natural resources like coal, petroleum or else increasing its availability to other important processes and one can hope that the waste heat recovery may play an even greater role in the industrial development in this new millennium. Key word: Boiling of juice, bagasse yields, crushing, scrubbing system, vacuum measurement, gur. Introduction: The sugar industry processes sugar cane and sugar beet to manufacture edible sugar. More than 60% of the worlds sugar production is from sugar cane, the balance is from sugar beet. Sugar manufacturing is a highly seasonal industry, with season lengths of about 6 to 18 weeks for beets and 20 to 32 weeks for cane. Approximately 10% of the sugar cane can be processed to commercial sugar, using approximately 20 cubic meters of water per metric ton (m3/t) of cane processed. Sugar cane contains 70% water; 14% fiber; 13.3% saccharose (about 10 to 15% sucrose), and 2.7% soluble impurities. Sugar canes are generally washed, after which juice is extracted from them. The juice is clarified to remove mud, evaporated to prepare syrup, crystallized to separate out the liquor, and centrifuged to separate molasses from the crystals. Sugar crystals are then dried and may be further refined before bagging for shipment. In some places juice is extracted by a diffusion process that can give higher rates of extraction with lower energy consumption and reduced operating and maintenance costs. For processing sugar beet (water, 75%; sugar, 17%), only the washing, preparation, and extraction processes are different. After washing, the beet is sliced, and the slices are drawn into a slowly rotating diffuser where a countercurrent flow of water is used to remove sugar from the beet slices. Approximately 15 cubic meters (m 3 ) of water and 28 kilowatt-hours (kWh) of energy are consumed per metric ton of beet processed. Sugar refining involves removal of impurities and decolonization. The steps generally followed include, affixation, melting, clarification, decolonization, evaporation, crystallization, and finishing. Decolonization methods use granular activated carbon, powdered activated carbon, ion exchange resins, and other materials. 1 Methodology

Features of pigment complex of red beet and patterns of its color changes

Red beet contains many biologically active substances, including such anthocyanins as betaine and betanin, which provide medical properties, and has a high content of catechins, flavonol glycosides, vitamins and minerals. Quantitative analysis of identified phenolic compounds indicates the varietal effect. Varietal incision contains from 218,4 • 10-3% (Single sprout) to 607,8-3% (Crimson) of anthocyanins. along with this, the content of betaine is between 19.7% (Delicious) to 42.9% (Bordeaux Kharkov) of the total content of anthocyanins, and betanin - from 57.1% (Bordeaux Kharkov) to 80.3% (Delicious). Varietal effect on the content in red beet of such low phenolic compounds as catechins (17.4 - 31.1%), flavonol glycosides (66.3 - 84.7%) and in some varieties of oxycinnamic acids (3.3 -13,0%) is also noticeable. Taking into account the achievements of other scientists, which state the lability of anthocyanins and dependence of their changes from the heat treatment duration, pH and other factors, as well as achieving the pigment stabilization by various protectors, we selected the following parameters of beet treatment: heat treatment (cooking) - 20 minutes; pH - 3.6; Melissa concentration in solution - 1%; size of beet slices - 15 mm. This method allows the preservation of 91 - 95% of beet pigment complex, and color features of the treated sample coincide with control features. Taking into account the achievements of other scientists, which state the lability of anthocyanins and dependence of their changes from the heat treatment duration, pH and other factors, as well as achieving the pigment stabilization by various protectors, we selected the following parameters of beet treatment: heat treatment (cooking) - 20 minutes; pH - 3.6; Melissa concentration in solution - 1%; size of beet slices - 15mm. This method allows the preservation of 91 - 95% of beet pigment complex, color characteristics of the treated sample coincide with control characteristics.

Filtration diffusivity and expression behaviour of thermally and electrically pretreated sugar beet tissue and press-cake

The expression behaviour of a sugar beet tissue pre-treated thermally (at 50 and 70°C) and electrically (by pulsed electric fields applied at 20°C and after preheating at 50 and 70°C) was studied at constant pressure (5bar). The filtration–consolidation behaviour of slices’ assemblies (press-cake of sugar beet slices) was studied and compared to that of disk sample. The application of a pulsed electric field (PEF) treatment (600Vcm−1 during 10ms) induces the electroporation of cell membranes and facilitates the expression process. It was demonstrated that after treatment of sugar beet tissue by heat (at 70°C), PEF, and combined (heat and PEF) pre-treatments, the solid–liquid expression followed the filtration–consolidation behaviour for both disk sample and slices’. The computational semi-empirical model employed in this paper allows the determination of the consolidation coefficient, which characterizes filtration diffusivity. Adjustment of experimental and model data showed that the filtration–consolidation behaviour of the disk sample was similar to that of slices’ assemblies. Model adjustment showed that experimental data reasonably well coincide with the model, which permits a good prediction of the compression behaviour of thermally and electrically treated tissue and press-cake.

Processamento de produto farináceo a partir de beterrabas submetidas à secagem estacionária

Processing flour product obtained from stationary beet drying. The consumption of dehydrated vegetables has been stimulated for their practical use, higher conservation time compared to in natura varieties, and the possibility of using surplus production, thus reducing the effects of seasonality. This research proposed the production of beet flour, using simple technology and procedures available for the majority of small producers. Different beet slices were compared: longitudinal (long 2; 4.5 and 9 mm) and cross-section (cross 2, 4.5 and 9 mm), about drying and grinding times, drying rates, dry flour yields, and particle size. Considering that the drying rate was low, that the length of time of the product in the dryer was low, that the flour had low particle size, and the ease of preparing slices, the treatments of 4.5 mm slices were recommended for the production of beet flour. The flour presented high dietary fiber, carbohydrate, protein and total mineral contents, and reduced lipid content.

Land substitution effects of biofuel side products and implications on the land area requirement for EU 2020 biofuel targets

The provision of biofuels today is based on energy crops rather than residual biomass, which results in the requirement of agricultural land area. The side products may serve as animal feed and thus prevent cultivation of other feedstock and the use of corresponding land area. These effects of biofuel provision have to be taken into account for a comprising assessment of land area requirement for biofuel provision. Between 18.5 and 21.1 Mio. hectares (ha) of land area is needed to meet the EU 2020 biofuel target depending on the biofuel portfolio when substitution effects are neglected. The utilization of the bioethanol side products distiller′s dried grain and solubles (DDGS) and pressed beet slices may save up to 0.7 Mio. ha of maize cultivation area in the EU. The substitution effect due to the utilization of biodiesel side products (oil cakes of rape, palm and soy) as animal feed may account for up to 7.1 Mio. ha of soy cultivation area in Brazil. The results show that the substitution of land area due to use of side products might ease the pressures on land area requirement considerably and should therefore not be neglected in assessing the impacts of biofuel provision worldwide.

Pulsed Electric Field Assisted Pressing of Sugar Beet Slices: towards a Novel Process of Cold Juice Extraction

The use of pulsed electric fields (PEF) as an intermediate treatment for the cold juice extraction from sugar beet ‘cossettes’ (i.e. long grated particles) has been investigated using a pilot scale multi-plate and frame pressing equipment (pressure of 5–15 bar; particles filling of 4·5–15 kg) and a pulse generator (1000 V–1000 A). It has been possible to validate laboratory-scale results (40 g of particles) by studying the feasibility and advantages of a PEF-assisted cold pressing of sugar beet cossettes on a much larger scale (4·5–15 kg). A best scheme scenario for an adequate PEF-assisted cold pressing of sugar beet cossettes consists of two initial pressing steps with an intermediate PEF treatment, followed by one or more washing steps and a final pulp pressing. A yield of about 80% in juice per initial mass of cossettes has been achieved before washing. By performing some washing and final pressing operations, losses of sugar in pulp could be significantly reduced to about 3% of the initial sugar content. The purity of pressed juices was systematically higher following PEF treatment compared to that of juices prior to PEF treatment (96–98% and 90–93%, respectively). Spectrophotometric colour measurements, reflecting impurities and fine suspended particles contents in juices, showed that purified PEF juices had colour values three to four times lower than those of purified factory juices, a difference confirmed by the colour of sugar crystals obtained from both types of juices. In addition, significant amounts of potassium, sodium and α-amino nitrogen were found to remain in PEF-treated particles, which explains why better purity juices are obtained following PEF treatment.

Factors Affecting the Winter-Feeding Ecology of Red Deer

Characteristics of browsing the forest regenerations and the consumption of supplementary given food of red deer were investigated. On a 10,000 ha territory managed by a forest management unit all the regenerations were fenced in due to the high browsing pressure. In the course of the experiment three plots of 0.5 ha-s each regenerated by oak ( Querqus robur ) were left unfenced. On the side of one plot a feeding station was built in which sugar beet slices were given supplementary. On the side of another plot maize fodder was offered, while the third one served as a control. All three plots were surrounded by sandy bands, to be able to count how many deer stepped in weekly the respective plot. During the freeze days deer used significantly less the regeneration plots, and consequently browsed less. The same was found during the snow cover. Although snow was as shallow as 5 cm in average, it caused a change in feeding strategy of deer. Regenerations covered by snow did not offer enough forage anymore, because the hiding of the forbs and grasses. On weeks with snow cover red deer consumed significantly more sugar beet slices, than on weeks without snow. On the days without snow cover the later the week during the winter was, the more sugar beet was consumed. Browsing pressure caused in average by one deer in the neighbouring of the feeding stations was significantly increased by giving supplementary maize or sugar beet slices.

Kinetic model of sugar diffusion from sugar beet tissue treated by pulsed electric field

AbstractExtraction of sugar from sugar beet slices was studied following various pulsed electric field (PEF) treatments (intensities from 300 to 800 V cm−1 and number of pulses varying between 50 and 1000). Slices treated by PEF were immersed in water at ambient temperature at a liquid/solid ratio of 3. A significant increase in extraction yield was observed. This enhancement was due to permeabilisation of the cellular membrane and to the additional quantity of juice appearing on the surface of slices after PEF treatment being extracted rapidly by convection. The optimal conditions of PEF treatment were an intensity of 670 V cm−1 and 250 pulses. The extraction kinetics was studied on the basis of two approaches: Fick's diffusion equation and a two‐exponential kinetic model. The coefficient of diffusion was only slightly influenced by the conditions of PEF treatment. The two‐exponential model successfully described both the rapid and prolonged stages of extraction. By heating the solution at mild temperatures of 30–50 °C, the coefficient of diffusion was increased and the kinetics of extraction was enhanced. The quality of cellular juice obtained after PEF treatment was higher than that of juice obtained after thermal pretreatment at 75 °C. Copyright © 2004 Society of Chemical Industry

Solid–liquid expression of cellular materials enhanced by pulsed electric field

The mechanism of solid–liquid expression enhanced by pulsed electric field (PEF) is studied for agrofood cellular materials. The application of PEF induces the permeabilization of cellular membranes and facilitates the subsequent cells rupture by mechanical compression. The solid–liquid expression was preceded by mechanical pre-compaction of sugar beet slices under a constant pressure, application of PEF treatment under the same pressure, and prolongation of mechanical compression after the PEF removal. The periods of solid–liquid expression enhanced by PEF are studied on the basis of press-cake electrical resistance measurement. The rheological model of solid–liquid expression with a fracture element can be used to estimate the compressibility characteristics of press-cake treated by PEF. A simple empirical equation predicted well the compression ratio of press-cake at different parameters of PEF. With increase of electrical energy input the liquid emanation from press-cake was intensified up to some level of expression, which seems to correspond to the destruction of quasi totality of cells.

Extraction and composition of pectins and hemicelluloses of cell walls of sugar beet roots grown in Morocco

Summary Cell‐wall polysaccharides were isolated as alcohol‐insoluble residues (AIR) from Moroccan sugar beet slices at two stages of the harvest season (early and late samples). Pectins and hemicelluloses were extracted by a sequential treatment with water, EDTA, hot dilute hydrochloric acid, cold dilute sodium hydroxide, cold 1 M and 4 M sodium hydroxide and finally water at pH 7. The highest extraction yields were obtained for the dilute acid and alkali treatments, which extracted pectins rich in arabinose. The extracts from the late sample were rich in glucose which, was not retained on DEAE Sepharose CL 6 B, and which may come from microbial growth on the fields after harvesting. Yields for hemicelluloses after extraction with 1 M NaOH were 12% and 13% of AIR, respectively, for early and late beet slices, and after extraction with 4 M NaOH 5% and 6%, respectively. The extracts were rich in arabinose, xylose and glucose, and contained fucose and mannose. Fractionation on DEAE Sepharose gave one major non‐retained fraction rich in neutral sugars, corresponding to xyloglucans and a minor retained fraction corresponding to heteroxylans, and residual pectins. Washing with water at pH 7 extracted pectins rich in rhamnose and galactose.