Forced-air Oven Research Articles

INFLUÊNCIA DO Al<sup>3+</sup> EM SOLUÇÃO NUTRITIVA NO CRESCIMENTO DE TRÊS ESPÉCIES FLORESTAIS UTILIZADAS NA RECUPERAÇÃO DE ÁREAS DEGRADADAS

Um dos principais fatores limitantes no desempenho das culturas agrícolas e florestais na maioria dos solos tropicais é o efeito tóxico do Al3+. No entanto, algumas espécies vegetais apresentam mecanismos de adaptação que lhes conferem tolerância a essas condições. O objetivo deste estudo foi avaliar o desenvolvimento de três espécies florestais cultivadas em solução nutritiva com diferentes níveis de Al3+. Para tanto, mudas de Acacia mangium, Mimosa artemisiana e Enterolobium contortisiliquum foram cultivadas em solução nutritiva com quatro concentrações de Al3+ (controle, 185, 370 e 555 mmol L-1) durante 95 dias. Ao final do experimento, as plantas foram segmentadas e uma fração conhecida das raízes foi digitalizada para estimativa de área e comprimento radicular. O caule, folhas e o restante das raízes foram secos em estufa de ventilação forçada, sendo determinada a biomassa e os teores de N, P e K no tecido vegetal. As espécies apresentaram padrões de crescimento diferenciados em função do aumento do teor de Al3+ na solução nutritiva, sendo que a Acacia mangium e a Enterolobium contortisiliquum foram mais tolerantes ao Al+3, demonstrando potencial de uso na recuperação de áreas degradadas e com solos ácidos. Os teores de N nas partes das plantas não foram influenciados pelo Al3+, no entanto, a concentração de P aumentou nas raízes das três espécies com níveis intermediários de Al3+, resultando em redução de P na parte aérea da Acacia mangium e Mimosa artemisiana. A concentração de K na Acacia mangium foi reduzida somente no menor nível de Al3+, enquanto para Mimosa artemisiana a redução foi gradativa.

Adiabatic packed column supercritical fluid chromatography using a dual-zone still-air column heater

An approach to conducting SFC separations under pseudo-adiabatic condition utilizing a dual-zone column heater is described. The heater allows for efficient separations at low pressures above the critical temperature by imposing a temperature profile along the column wall that closely matches that for isenthalpic expansion of the fluid inside the column. As a result, the efficiency loss associated with the formation of radial temperature gradients in this difficult region can be largely avoided in packed analytical scale columns. For elution of n-octadecylbenzene at 60 °C with 5% methanol modifier and a flow rate of 3 mL/min, a 250 × 4.6-mm column packed with 5-micron Kinetex C18 particles began to lose efficiency (8% decrease in the number of theoretical plates) at outlet pressures below 142 bar in a traditional forced air oven. The corresponding outlet pressure for onset of excess efficiency loss was decreased to 121 bar when the column was operated in a commercial HPLC column heater, and to 104 bar in the new dual-zone heater operated in adiabatic mode, with corresponding increases in the retention factor for n-octadecylbenzene from 2.9 to 6.8 and 14, respectively. This approach allows for increased retention and efficient separations of otherwise weakly retained analytes. Applications are described for rapid SFC separation of an alkylbenzene mixture using a pressure ramp, and isobaric separation of a cannabinoid mixture.

Chemical and Spectral Characterization of The Ozonation Products of κ-Carrageenan

Kappa (κ-) carrageenan oligomers are known to have several biological activities. Recent progress in the development of modified κ-carrageenan has resulted low molecular of κ-carrageenan. Ozone is a powerful oxidant and considered for depolymerization of κ-carrageenan. However, few studies have investigated the changes in κ-carrageenan properties associated with ozone treatment. This study would investigate on the changes in chemical structure after ozonation process. The experiments were carried out in a glass reactor equipped with an ozone bubble diffuser. Ozone with concentration of 80 ± 2 was bubbled into the solution. The ozone treatment was conducted at different times, i.e., 0 (control), 5, 10, 15, and 20 minutes. The experiments were conducted at pH 7 and constant stirring speed (200 rpm). Ozone-treated κ-carrageenan was dried at 60 ºC for 24 h in a forced air oven. The chemical and spectral analyses of κ-carrageenan after ozonation process were carried out using UV-Vis and FT-IR spectroscopy. These changes are seen in the UV spectra as a high intensity of absorbance peak at 290 nm. It is shows that ozonation of κ-carrageenan leads to some chemical changes such as the formation of carbonyl, carboxyl or double bonds.The FT-IR spectra reveals that the chemical structure of degraded κ-carrageenan, in term of sulfate content, is only slightly affected by the ozone treatment.

MÉTODO DE OBTENÇÃO DE MATÉRIA SECA E COMPOSIÇÃO QUÍMICA DE VOLUMOSOS

Resumo Objetivou-se avaliar a influência do método de secagem sobre a composição nutricional de diferentes volumosos. Foram utilizadas quatro gramíneas (Urochloa brizantha cv. Marandu, Urochloa brizantha cv. MG4, Cynodon dactylon cv. Coastcross e Panicum maximum cv. Áries), uma leguminosa forrageira, o estilosante (Stylosanthes cv. Campo Grande) e duas silagens (Zea mays e Triticum aestivum cv. BRS Umbu). Os métodos de secagem se basearam no uso da estufa de ventilação forçada e de forno de micro-ondas. O delineamento estatístico utilizado foi um arranjo fatorial 2 x 8 (2 métodos de secagem e 8 volumosos) com 4 repetições. O método de secagem não influenciou o conteúdo de matéria seca das forragens. A secagem em forno micro-ondas elevou os teores de fibra em detergente neutro nos volumosos avaliados. Houve interação entre o método de secagem e tipo de forragem avaliada, com relação à proteína bruta (estilosante), extrato etéreo (MG4, estilosante e Áries) e nitrogênio insolúvel em detergente neutro (Coastcross, MG4, Marandu e estilosante). O forno de micro-ondas pode ser utilizado como instrumento para obtenção da matéria seca em alimentos volumosos, porém, a técnica pode afetar a composição da forragem avaliada.

Drying kinetics of ‘babassu’ mesocarp

ABSTRACT ‘Babassu’ mesocarp flour has been used by the pharmaceutical, human food and animal feed industries. However, there is lack of standardization in the production, as well as absence of information on the management of the product’s quality. Thus, the objective of this study was to dry the ‘babassu’ mesocarp in forced-air oven and solar dryer, adjust different mathematical models to the experimental data, as well as to quantify the levels of proteins and crude fiber of the produced flour. The criteria for the adjustment were the coefficient of determination, magnitude of the mean relative error, standard deviation of estimate and the residual distribution trend. Drying in the shortest time occurred in oven at 60 °C (370 min), leading to water content of 4.62%, while in the solar dryer the final water content was 8.07% in 6 days. The mathematical model Two Terms showed the best fit to the experimental data for oven drying and the Midilli model showed the best fit in solar dryer. There was an increase in protein content with the drying in solar dryer and oven at 40, 50 and 60 °C (1.36, 1.33, 1.15 and 1.37%, respectively) in relation to fresh mesocarp (0.88%). Drying in both oven and solar dryer promoted increase of protein in the flour.

DRYING EXPERIMENT FOR THE TEACHING OF SIMULTANEOUS MASS AND HEAT TRANSFER

Drying is a process widely applied industrially, especially in food technology. It usually consists of a dehydration operation, removing enough water to halt microbial development. This allows an increased shelf life and a broader range of products available to the consumer, also reducing packaging, storage and transportation costs. This work presents a simple apple dehydration experiment, suited for the teaching of simultaneous mass and heat transfer in engineering classes. The procedure for drying sliced apples in a forced air oven is presented. Data collected was analyzed using the theoretical model proposed by Crank (Crank, 1975), so that it was possible to evaluate the effective diffusion coefficient of moisture. The empiric model proposed by Page (Page, 1949) was also tested to fit data.

Effects of drying procedures on chemical composition and nutritive value of alfalfa forage

The effects of various drying procedures of alfalfa forage were evaluated on chemical composition, in vitro neutral detergent fibre (NDF) and dry matter (DM) digestibility, in situ DM, organic matter and crude protein (CP) degradability. The alfalfa had been harvested in the spring growth (early bud and flowering) and first regrowth (late bud and late flowering) periods. The samples were dried at 30 °C (T30), 40 °C (T40), 50 °C (T50), 60 °C (T60) and 100 °C (T100) in a forced-air oven or frozen for one month and then freeze-dried (TFD) or oven-dried at 50 °C (TFREE). Another drying procedure included pre-treatment by heating in a microwave oven (TMO) or in a forced-air oven at 100 °C for 1 hour (T100+50) and then oven-dried at 50 °C. The freeze-drying method was chosen as a reference method. Freeze-dried samples had the lowest NDF, acid detergent fibre (ADF), acid detergent lignin (ADL), neutral detergent insoluble protein (NDIP) and acid detergent insoluble protein contents (P <0.05). Additionally, freeze-dried products had the highest CP, in vitro true digestibility of DM and CP degradability values (P <0.05). There was no added benefit of the TMO in the chemical composition, in vitro digestibility or in situ degradation compared with T50. This study showed that T50 can yield chemical composition, in vitro and in situ results that are similar to those obtained with the freeze-drying method and that this procedure is useful for forage analyses and evaluation.Keywords: freeze-drying, insoluble nitrogen, in vitro digestibility, oven-drying, ruminants

Relationship between processing score and kernel-fraction particle size in whole-plant corn silage

Kernel processing increases starch digestibility in whole-plant corn silage (WPCS). Corn silage processing score (CSPS), the percentage of starch passing through a 4.75-mm sieve, is widely used to assess degree of kernel breakage in WPCS. However, the geometric mean particle size (GMPS) of the kernel-fraction that passes through the 4.75-mm sieve has not been well described. Therefore, the objectives of this study were (1) to evaluate particle size distribution and digestibility of kernels cut in varied particle sizes; (2) to propose a method to measure GMPS in WPCS kernels; and (3) to evaluate the relationship between CSPS and GMPS of the kernel fraction in WPCS. Composite samples of unfermented, dried kernels from 110 corn hybrids commonly used for silage production were kept whole (WH) or manually cut in 2, 4, 8, 16, 32 or 64 pieces (2P, 4P, 8P, 16P, 32P, and 64P, respectively). Dry sieving to determine GMPS, surface area, and particle size distribution using 9 sieves with nominal square apertures of 9.50, 6.70, 4.75, 3.35, 2.36, 1.70, 1.18, and 0.59mm and pan, as well as ruminal in situ dry matter (DM) digestibilities were performed for each kernel particle number treatment. Incubation times were 0, 3, 6, 12, and 24 h. The ruminal in situ DM disappearance of unfermented kernels increased with the reduction in particle size of corn kernels. Kernels kept whole had the lowest ruminal DM disappearance for all time points with maximum DM disappearance of 6.9% at 24 h and the greatest disappearance was observed for 64P, followed by 32P and 16P. Samples of WPCS (n=80) from 3 studies representing varied theoretical length of cut settings and processor types and settings were also evaluated. Each WPCS sample was divided in 2 and then dried at 60°C for 48 h. The CSPS was determined in duplicate on 1 of the split samples, whereas on the other split sample the kernel and stover fractions were separated using a hydrodynamic separation procedure. After separation, the kernel fraction was redried at 60°C for 48 h in a forced-air oven and dry sieved to determine GMPS and surface area. Linear relationships between CSPS from WPCS (n=80) and kernel fraction GMPS, surface area, and proportion passing through the 4.75-mm screen were poor. Strong quadratic relationships between proportion of kernel fraction passing through the 4.75-mm screen and kernel fraction GMPS and surface area were observed. These findings suggest that hydrodynamic separation and dry sieving of the kernel fraction may provide a better assessment of kernel breakage in WPCS than CSPS.

Use of a Modified Chemical Fractionation Scheme to Characterize Organic Nitrogen in Wetland Soils

Soil organic nitrogen (SON) is the main source of available N to microbes through mineralization. Although the importance of SON is recognized, the chemical nature of SON is not well described mainly because of methodological limitations. The objective of this study was to modify the operationally defined SON fractionation scheme to improve sample processing time. The operationally defined SON pools are amino sugar N, amino acid N, and hydrolyzable unknown N. Modifications to the method included: SON hydrolysis using an electric griddle, use of 0.05 mol L−1 H2SO4 NH3 traps, and use of a forced-air oven during amino acid N deamination. The modified method improved sample throughput by (i) increasing soil extractions from one to 12 samples at a time, (ii) decreasing sample analysis time by using colorimetric methods, and (iii) reducing temperature variability during amino acid N deamination. We estimate that the method modifications save on average 5 h per 12 samples. The modified method was then applied to 10 flooded or drained wetland soils that ranged from 3 to 34 g kg−1 total N (TN). The labile SON pools ranged from 0.06 to 1.29 g kg−1 amino sugar N and 0.74 to 10.5 g kg−1 amino acid N. Amino sugar N linearly increased with soil total C (TC; R2 = 0.60). Amino acid N exponentially increased with TC (R2 = 0.80), suggesting that conditions in wetlands preferentially conserve amino acid N. A decline in amino acid N with drained conditions highlighted the potential loss of TN stored in wetlands, estimated at 50 to 75 Pg.

Comparisons of in vitro fermentation and high moisture forage processing methods for determination of neutral detergent fiber digestibility

Neutral detergent fiber digestibility (NDFD) determined in vitro with rumen inoculum is widely used to assess digestibility and potential energy contributions of feedstuffs. An in vitro fermentation system (IVFS) with potential to improve sample throughput and ease of handling for NDFD determination was investigated. Additionally, methods for preparing high moisture forages and their effect on in vitro NDFD were evaluated. In the IVFS study, a commonly used method that uses Erlenmeyer flasks under continuous CO2 pressure in water baths (GV) was compared to a system that uses sealed glass tubes in a shaking incubator (TU). Fibrous feeds (alfalfa hay, maize silage, soyhulls, and ryegrass hay) were incubated in duplicate for 24, 30, and 48h in three fermentation runs (run) in both IVFS. Overall, NDFD was greater for TU than GV at 24h, and greater for GV than TU at 48h. Maize silage had lower values with TU than GV, with the difference increasing with fermentation time, possibly due to low pH related to amount of fermentable substrate used. Within-run variability at 48h was less with GV than TU. Variability of NDFD across runs was or tended to be less for TU at 24 and 30h, and tended to be less for GV at 48h. In the forage processing study, silages (alfalfa, maize) and pasture grasses (meadow fescue, orchardgrass, reed canarygrass, ryegrass) were ground with dry ice through a meat grinder to pass 4.5mm openings. Subsamples were dried in a 55°C forced-air oven (OD), freeze dried (FD), or retained as undried frozen (UF) material. Samples were fermented in duplicate in TU for 24, 30, and 48h in two runs. NDFD response to processing varied by forage with FD for orchardgrass and UF for maize silage lower than other treatments for those forages. Overall, NDFD did not differ among processing methods at 24h, was greatest for OD and UF at 30h, and for OD at 48h. Based on NDFD and analytical variability results, TU may be recommended at 24 and 30h and GV at 48h, however, substrate amount may need to be restricted in TU to avoid depressing NDFD. Methods of processing high moisture forage samples for NDFD analysis showed no clear advantage for using freeze dried or undried forage over oven dried materials.

Toxicity of the phenolic extract from jabuticabeira (Myrciaria cauliflora (Mart.) O. Berg) fruit skins on Spodoptera frugiperda

Fall armyworm, Spodoptera frugiperda J.E. Smith, 1797 (Lepidoptera: Noctuidae) is the main pest of maize, besides attacking sorghum and cotton crops. The control of this pest has been accomplished mainly with the use of synthetic insecticides but, due to the growing concern about the environment and food quality, phenolic compounds have shown their potential for the biological control of this insect. Thus, the objective of the present study was to evaluate the efficiency of the extract of jabuticabeira, Myrciaria cauliflora [Mart.] O. Berg (Myrtaceae) fruit skin flour in the control of S. frugiperda. Skins of M. cauliflora Sabara genotype were dried at 45 °C in a forced air oven. In order to obtain the extract, 1.0 g flour was mixed with 10 mL acetone: water solution (7:3 v/v). Forty-eight-hour-old S. frugiperda caterpillars were placed in glass tubes with an artificial diet containing the extract at concentrations of 0, 250, 500, 1000, and 2000 mg L-1. The extract, in which the phenolic compounds gallic acid, gallocatechin, catechin, epicatechin, ellagic acid, and salicylic acid were identified at a concentration of 2000 mg L-1, in average, increased mortality rates by 150% in the larval stage, duration of larval stages by 60%, and pupal by 17%, and decreased amount of females by 55%. On the other hand, the extract at 1000 mg L-1 only increased duration of larval period by 24%. It was concluded that the extract is harmful to this insect, probably due to the presence of phenolic compounds.

Extending the limits of operating pressure of narrow-bore column liquid chromatography instrumentation

The increase of the operating pressure in Liquid Chromatography, has been one of the crucial steps toward faster and more efficient separations. In the present contribution, it was investigated if the pressure limits for narrow-bore columns (2.1mm ID) could be increased beyond those of commercially available (1300bar) instrumentation without performance loss. Whereas previous studies applying pressures higher than 2000bar were limited to the use of columns with a diameter smaller or equal to 1mm, it is a difficult feat to expand this to 2.1mm ID given that viscous-heating effects increase according to the fifth power of the column radius. A prototype LC set-up was realized, allowing to operate at pressures up to 2600bar (260MPa) for large separation volumes (>5mL). The performance of an in-house-built injector was compared at 800bar to commercially available injectors, yielding equal performance but twice the maximum pressure rating. The performance of (coupled) custom columns packed with fully porous and superficially porous particles were assessed at ultra-high-pressure conditions. Increasing the inlet pressure from 800 to 2400bar and scaling the column length proportionally (from 150mm to 450mm), resulted in the theoretically expected linear increase in plate count from 20,000 to 59,000. A maximum plate number of 81,000 was realized using a 600mm long (coupled) column at 2600bar. Viscous-heating effects were diminished by insulating coupled columns and applying an intermediate-cooling strategy in a forced-air oven.

Comparison of on-farm forage-dry-matter methods to forced-air oven for determining forage dry matter

The objective of the study was to compare 3 different on-farm methods of determining DM in forages using traditional forced-air oven (FAO) as a standard for comparison. Silage samples (60 corn silage, 35 grass silage) were analyzed by microwave (MW), Koster Moisture Tester, Q-Dry (a new automatic convection system to measure DM), and FAO using standard or manufacturers’ methods for each system. A linear relationship was observed for corn silage between FAO and MW (β = 1.014; R 2 = 0.961), Koster Moisture Tester (β = 1.028; R 2 = 0.885), and Q-Dry (β = 0.982; R 2 = 0.921), where β is slope of the regression line and R2 is coefficient of determination. In addition, grass silage showed a significant relationship between FAO and MW (β = 1.021; R2 = 0.961), Koster Moisture Tester (β = 1.245; R 2 = 0.950), and Q-Dry (β = 0.965; R 2 = 0.952). All methods resulted in similar DM determination, exhibiting a strong, linear relationship with FAO (P < 0.01), and all have advantages and disadvantages. Microwave and Q-Dry showed the strongest correlations to FAO. These data suggest that MW and Q-Dry are the best on-farm alternatives to traditional oven drying for DM determination.

Accumulation of phosphorus fractions and contamination potential in vineyard soils in the southern region of the state of Santa Catarina, Brazil

In vineyards, if phosphate is applied both before planting and at intervals during growth without consideration of technical criteria, the soil P fractions may be increased and their proportions altered. This study was carried out to evaluate the accumulation of P fractions and the parameters of the adsorption isotherm in a sandy Typic Hapludalf soil in vineyards with a history of successive and excessive phosphate fertilization. In December 2010, two vineyards were selected, one 4 and the other 15 years old, in Urussanga, State of Santa Catarina (Brazil). Three trenches were dug in each area and soil was collected from the 0-5, 5-10 and 10-20 cm depth ranges. The soil samples were dried in a forced-air oven, sieved and subjected to chemical analyses, P chemical fractionation and P adsorption isotherms. Excessive phosphate fertilization, before and during cultivation, particularly in the older vineyard and, consequently, with a longer history of phosphate fertilization, increased the inorganic P concentrations to the depth of 20 cm, especially in labile fractions extracted by anion exchange resin and NaHCO3 in the non-labile fraction, as well as in the non-labile fraction extracted by 1.0 mol L-1 HCl. The application of phosphate fertilizers and the long cultivation period increased the P levels in the organic labile fraction extracted by 0.5 mol L-1 NaHCO3, and especially in the moderately labile fraction extracted by 0.1 and 0.5 mol L-1 NaOH. Phosphate fertilization of older vineyards, i.e., cultivated for 15 years, increased the amounts of P desorbed in water, indicating a risk of contamination of surface waters and groundwater. The phosphate fertilization before planting, without considering the results of soil analysis, and during cultivation, disregarding the results of soil analysis, leaf analysis and expected yield, led to a reduction in the maximum P adsorption capacity in the 0-5 cm layer of vineyard 2, indicating saturation of part of the reactive particle adsorption sites.

English

&nbsp; This study aimed to determine the effect of drying conditions and storage time on crambe seed quality. Crambe fruits with a moisture content of 27.0 &plusmn; 1.0% (wet basis; w.b.) were used. These fruits were dried in a forced-air oven and were kept under controlled temperatures of 35, 45, 60, 75 and 90&deg;C at relative humidities of 20.9, 8.7, 6.8, 4.8 and 2.3%, respectively. During the drying process, trays containing 0.4 kg of fruit were periodically weighed until the final drying point of 7.0 &plusmn; 1.3% (w.b.). The fruits were packed in glass jars covered with permeable fabric. Each container had 400 g of fruit, and the containers were kept under ambient conditions (temperature of 26 &plusmn; 3&deg;C and relative humidity of 55 &plusmn; 12%). The temperature and relative humidity of the environment were recorded by a digital datalogger. The samples were evaluated at 0, 3, 6, 9 and 12 months for moisture content, electrical conductivity (EC), germination percentage and germination speed index (GSI). Drying the crambe fruit at high temperatures caused a decrease in the physiological quality of the seeds. There was an increase in the amount of electrolytes released by the seeds over time. Seeds stored for 12 months at room temperature had superior germination regardless of drying temperature. &nbsp; Key words:&nbsp;Physiological quality,&nbsp;Crambe abyssinica,&nbsp;biodiesel.

Osmotic Pellet System Comprising Osmotic Core and In-Process Amorphized Drug in Polymer–Surfactant Layer for Controlled Delivery of Poorly Water-Soluble Drug

The aim of the present investigation was to develop controlled porosity osmotic system for poorly water-soluble drug based on drug in polymer-surfactant layer technology. A poorly water-soluble drug, glipizide (GZ), was selected as the model drug. The technology involved core of the pellets containing osmotic agent coated with drug dispersed in polymer and surfactant layer, finally coated with release-retardant layer with pore former. The optimized drug-layer-coated pellets were evaluated for solubility of GZ at different pH conditions and characterized for amorphous nature of the drug by differential scanning calorimetry and X-ray powder diffractometry. The optimized release-retardant layer pellets were evaluated for in vitro drug release at different pH, hydrodynamic, and osmolality conditions. The optimized drug layer showed improvement in solubility (10 times in pH 1.2, 11 times in pH 4.5, and 21 times in pH 6.8), whereas pellets coated with cellulose acetate (15.0%, w/w, weight gain) with pore former triethyl citrate (10.0%, w/w, of polymer) demonstrated zero-order drug release for 24 h at different pH conditions; moreover, retardation of drug release was observed with increment of osmolality. This system could be a platform technology for controlled delivery of poorly water-soluble drugs.

Interaction between Carbon Black and Antioxidants in High-Density Polyethylene Pipe Resin

This paper presents the interaction between carbon black and antioxidants in high-density polyethylene. The 11 formulations prepared for this study were composed of furnace black with particle sizes of 27 and 75 nm at 2% to 5% by weight and different concentrations of antioxidants Irganox 1010 and Irgafos 168. The chemical interactions between the carbon black and the antioxidants were accelerated by elevated temperatures of 85°C in a forced-air oven. The relative amount of antioxidants retained in the samples throughout the incubation was measured using the oxidative induction time (OIT) test. The results showed that the initial OIT value increased with the weight percentage of the carbon black in the sample. A higher initial OIT value was found in the samples that had been blended with the 27-nm carbon black than in those blended with the 75-nm carbon black at the same concentration. Also, faster OIT depletion was detected in the samples that had been blended with the 27-nm carbon black than in those blended with the 75-nm carbon black at greater than 2% by weight. The carbon black–antioxidant interaction was found to be influenced by the carbon black–specific surface area and physical structure. Overall, the OIT decreased substantially faster in the samples with carbon black than in those without it. The reactions between the carbon black and the antioxidants were so strong that only a minor difference in the depletion rate was observed between the two antioxidant formulations.

Effects of Drying Process on the Physicochemical Properties of Nopal Cladodes at Different Maturity Stages

Chemical proximate analysis was done in order to determine the changes of nutritional characteristics of nopal powders from three different maturity stages 50, 100, and 150days and obtained by three different drying processes: freeze dried, forced air oven, and tunnel. Results indicate that nopal powder obtained by the process of freeze dried retains higher contents of protein, soluble fiber, and fat than the other two processes. Also, freeze dried process had less effect on color hue variable. No changes were observed in insoluble fiber content, chroma and lightness with the three different drying processes. Furthermore, the soluble fibers decreased with the age of nopal while insoluble fibers and ash content shows an opposite trend. In addition, the luminosity and hue values did not show differences among the maturity stages studied. The high content of dietary fibers of nopal pad powder could to be an interesting source of these important components for human diets and also could be used in food, cosmetics and pharmaceutical industry.

Real-Time Viscosity Measurements during the Accelerated Aging of Biomass Pyrolysis Oil

An oak bio-oil was aged at 90 °C using various times and methods. A novel method for aging bio-oils under shear is introduced and compared to standard (quiescent) aging experiments. In a hermetically sealed concentric cylinder rheometer, aging with shear for 8, 16, and 24 h showed increases in viscosity of 57, 300, and 720%, respectively. A similar increase in viscosity was observed after quiescently aging of sealed samples in a forced air oven (100, 120, and 740% after 8, 16, and 24 h, respectively). Another aging experiment under shear consisted of three 8 h aging steps with intermediate viscosity measurements. Viscosity increases were comparable to the 8, 16, and 24 h tests. A control experiment in the rheometer without shear found the increase in viscosity to be 30–50% less than the sheared experiments. The number-average molecular weight increased as samples were heat-treated at 90 °C for longer times. The water content showed small increases and decreases with aging, which was attributed to the hete...

Continuous vs. Rotational Grazing of Cool Season Pastures During the Summer Months

Continuous vs. Rotational Grazing of Cool Season Pastures During the Summer Months