Measurement of wood grain angle, moisture content and density using microwaves

In many wood products manufacturing processes, it is important to ensure that the physical properties of the raw material lie within acceptable ranges and are measured reliably. It is also important for practical use that the measurement process is robust, low-maintenance, fast and preferably non-contacting. This paper describes the development and demonstration of a microwave system for simultaneously identifying wood grain angle, moisture and density. The method involves propagating a microwave beam through the wood and measuring the resulting depolarization, attenuation and phase shift. The wood physical properties can then be identified from these measurements. In a series of measurements, the prototype microwave system successfully identified wood grain angles for hemlock and Douglas fir respectively with standard errors of 0.9° and 2.5° (measured range = -90° to +90°), moisture content 1.2% and 1.9% (measured range = 7–28%), moisture density 3.7 kg/m³ and 7.9 kg/m³ (measured range = 40–150 kg/m³, and dry density 16 kg/m³ and 30 kg/m³ (measured range = 325–625 kg/m³).     

Sensory properties of low fat cheddar cheese:effect of salt content and adjunct culture

The influence of salt concentration and of direct-to-vat culture adjuncts (DVCA) on the sensory properties of low fat hard cheese of the cheddar type has been investigated. Salt content has a major influence, and, at a level of 1·8%, low fat cheese with high levels of cheddar flavour and low bitter scores was produced. In addition, further enhancement of flavour was achieved by use of DVCA. Using the methodology described in this report, low fat cheese was manufactured which corresponded in flavour level and balance to that of commercial mature full fat cheese. Nevertheless, textural differences between low fat and full fat product remain to be resolved.     

Mold resistance of medium density fiberboard panels made from black spruce, hybrid poplar, larch and a mixture of S-P-F chips

Eleven types of medium density fiberboard (MDF) panels were manufactured from fresh-felled trees of black spruce, hybrid poplar, larch and a mixture of spruce, pine and fir (S-P-F) wood chips at a target density of 740 kg/m³ bonded with 10% commercial urea-formaldehyde (UF) resin. Black spruce panels were fabricated from fibers located in three wood age zones (1–20, 21–40 and over 40 annual rings) of bottom logs, as well as top, middle and bottom logs, separately. Hybrid poplar panels were made from three clones with codes 915303, 915311, and 915313. Mold resistance of these panels was tested by exposing panels in an incubation chamber set at favourable temperature and relative humidity (RH) conditions for mold growth for 4 weeks. The results indicate that MDF panels made from black spruce juvenile wood (1–20 annual rings) were more resistant to mold infection comparing to the other types of panels based on Duncan’s multiple-range test at 0.05 of probability. Panels made of fibers taken from black spruce transition zone (21–40 annual rings) and mature wood zone (over 40 annual rings), and top, middle and bottom logs, hybrid poplar clones 915303, 915311, and 915313, larch and S-P-F wood chips were not significantly different, and these panels were severely infected by mold after 4 weeks of incubation. Nine fungal species predominately infected the tested samples. This laboratory experiment indicates that MDF panels made from black spruce transition and mature wood, and top, middle and bottom logs, hybrid poplar, larch and a mixture of S-P-F chips are susceptible to mold growth and protection measures are necessary in order to improve mold susceptibility of those panels when used in humid conditions or for exterior applications.

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Schimmelbeständigkeit von MDF-Platten aus Schwarzfichte, Hybridpappel, Lärche und einem Spangemisch aus Fichten-, Kiefern- und Tannenholz

Zusammenfassung Aus frischem Schwarzfichten-, Hybridpappel- und Lärchenholz sowie einem Spangemisch aus Fichten-, Kiefern- und Tannenholz (S-P-F) wurden elf verschiedene MDF-Plattentypen mit einer Solldichte von 740 kg/m³ und einem Anteil von 10% handelsüblichen UF-Harz hergestellt. Die Fichtenplatten wurden aus Fasern von drei verschiedenen Alterszonen (1–20, 21–40 und ausserhalb des 40 Jahrrings liegend) vom untersten Stammabschnitt, sowie separat vom oberen, mittleren und untersten Stammabschnitt, hergestellt. Die Platten aus der Hybridpappel wurden aus den drei Klonen 915303, 915311 und 915313 hergestellt. Die Schimmelbeständigkeit dieser Platten wurde untersucht. Dabei wurden die Platten in einer Inkubationskammer bei einer für Schimmelwachstum günstigen Temperatur und relativen Luftfeuchte für vier Wochen gelagert. Die Ergebnisse zeigen, dass MDF-Platten aus juvenilem Holz der Schwarzfichte (1–20 Jahrring) verglichen mit den anderen Plattenarten gegen Schimmelbefall beständiger sind (basierend auf dem Duncan-Test 0,05). Platten aus Fasern von der Übergangszone vom juvenilen zum adulten Holz der Schwarzfichte (21–40 Jahrring) und von adultem Holz (ausserhalb 40 Jahrring) sowie vom oberen, mittleren und untersten Stammabschnitt, von Hybridpappelklonen 915303, 915311 und 935313, von der Lärche sowie einem Spangemisch aus Fichten-,Kiefern- und Tannenholz unterschieden sich nicht wesentlich. Diese Platten waren nach einer vierwöchigen Inkubationszeit stark von Schimmel befallen. Die Proben wurden überwiegend von neun Pilzarten befallen. Dieser Laborversuch zeigt, dass MDF-Platten aus Holz aus der Übergangszone und adultem Holz der Schwarzfichte, sowie von oberen, mittleren und untersten Stammabschnitten, Hybridpappel, Lärche und aus einem Spangemisch von Fichten-,Kiefern- und Tannenholz anfällig gegenüber Schimmelbefall sind. Aus diesem Grunde müssen vorbeugende Massnahmen ergriffen werden, um die Schimmelanfälligkeit dieser Platten bei Verwendung unter feuchten Bedingungen oder bei Aussenanwendungen zu reduzieren.

     

直径和线密度通用关系的研究

通过线密度预测纱线直径的方法是目前最为认可的表述之一,正在广泛使用。这一表述采用1.1为通用比容,而非1.1g/cm~3的纱线密度,提出用另一种相关理论模型计算纱线直径,也提出了纱线细度和长丝直径间关系的理论。线密度表述中,采用了预定的固定比容,因此该方法仅限用于英支支数的棉纱;通用比容模型只可在纤维密度(ρfiber)与纱线密度(ρyarn)一致的情况下使用。有关长丝的理论,采用了预定的密度和线密度(D),直径预测被限用于芳纶长丝和黏胶人造丝中。以上提到的各种理论都可在进一步的研究中用于修正和完善现有理论,旨在减轻目前工作的局限性。因此目前已经对有关常用经验公式进行了修正,以根据纱线密度和支数预测纱线直径;在现有的线密度(D)和直径(μm)关系中,提出可不考虑任何密度和原料的因素。统计关系也经检验和报道,检验分析结果显示了便于正确应用的更细微的细节。     

Evaluation of antioxidant and antimicrobial properties of biocompatible low density polyethylene/polyaniline blends

Melt processed blends of linear low density polyethylene (LLDPE) and polyaniline, in nanorod form, synthesized via the “falling pH” method (NR-PANI), with 5%, 10%, 15% and 20% NR-PANI loading, were evaluated for active packaging applications. The oxygen permeability decreased as the amount of NR-PANI in the blends increased. The blends films also exhibited antimicrobial and antioxidant capabilities. The oxidation of fish oil was delayed in the presence of the NR-PANI/LLDPE blends, and there was a negative correlation between oxidation and the NR-PANI content in the films. Moreover, the blends films were biocompatible to mammalian cells, meaning that NR-PANI/LLDPE films can potentially be utilized for a range of active packaging applications.     

The effect of pasteurisation and freezing on the low density lipoproteins of egg.

The low density fraction of egg yolk was separated by gel filtration into two groups of lipoproteins. One group (1) had an extremely high molecular weight and was probably formed by aggregation of the second group (2), which itself had a high molecular weight. In liquid egg the ratio of group 1 to group 2 was increased by pasteurisation for 5 min at 65°C and also by freezing and thawing of either raw or pasteurised material. When group 2 was isolated by gel filtration and then frozen and thawed it was converted to group 1.     

Evaluation of nitrogen content in cabbage seedlings using hyper-spectral images

Monitoring of nutrient status of crops is essential for better management of crop production. Nitrogen is one of the most important elements in fertilizer for the growth and yield of vegetable crops. In this study, nitrogen content of cabbage seedlings was evaluated using hyper-spectral images. Cabbage seedlings, cultured at five nitrogen fertilization levels, were planted in the 128-cell plug trays and grown in a phytotron at National Taiwan University. The images, ranged from 410 to 1,090 nm, of cabbage seedlings were analyzed by a hyper-spectral imaging system consisting of CCD cameras with liquid crystal tunable filters (LCTF), which was developed in this study. The digital images of seedling canopies were processed including image segmentation, gray level calibration and absorbance conversion. Models including modified partial least square regression (MPLSR), step-wise multi-linear regression (SMLR) and artificial neural network with cross-learning strategy (ANN-CL) were developed for the determination of the nitrogen content in cabbage seedlings. The three significant wavelengths derived from SMLR model are 470, 710, and 1,080; and the best result is obtained by ANN-CL model, in which r_c = 0.89, SEC = 6.41 mg/g, r_v = 0.87, and SEV = 6.96 mg/g. The ANN-CL model is more suitable for the remote sensing in precision agriculture applications because not only its model accuracy but also only 3 wavelengths are needed. This paper has been presented in the conference on “Optics for Natural Resources, Agriculture, and Foods II”, this conference is part of the SPIE Optics East event which was held 9–12 September 2007 at the Seaport World Trade Center in Boston, Massachusetts USA.     

用混合线性分析法建立苹果糖度近红外光谱预测模型

用混合线性分析法的一种变形算法建立了苹果糖度近红外光谱预测模型，并与偏最小二乘模型进行比较。结果表明：虽然最佳的混合线性分析法模型（18个主因子）比最佳偏最小二乘模型（11个主因子）复杂．但其精度却明显优于偏最小二乘模型：利用梗正集的28个苹果样本建立的糖度混合线性分析法校正模型，其相关系数r^2和标准偏差SEC分别为0．92509和0．40618；该校正模型经预测集的11个样本验证，相关系数r^2和标准偏差SEP分别达到0.87611和0．48480。混合线性分析法建立的糖度模型对苹果光谱的校正标准偏差SEC和预测标准偏差SEP分别比PLS法的SEC（0．41473）和SEP（0．50473）减小了2％和3．9％。结果表明：在诸如苹果糖度这一类农产品品质综合指标（非纯组分含量指标）的光谱检测中，应用混合线性分析法进行定量分析是完全可行的。并且其结果可与偏最小二乘法（PLS）的结果相媲美。     

The effect of cooking and processing on the glucosinolate content: Studies on four varieties of portuguese cabbage and hybrid white cabbage

The concentrations of individual and total glucosinolates were measured in four types of Portuguese cabbage and in one hybrid white cabbage before and after cooking. Typical Portuguese culinary procedures include boiling the cabbage for 10 min but for particular kale types the leaves are first shredded then boiled for 5 min (Caldo verde). Analysis of the fresh cabbage, cooked leaves and cooking water showed that the glucosinolate content of the cabbages is reduced by more than 50%. Almost all of this loss is accounted for as intact glucosinolates in the cooking water, normally used for soups in Portugal.     

Influence of wood moisture content on bending and shear stiffness of cross laminated timber panels

The bending and shear stiffness of cross-laminated timber (CLT) made from softwood depend on the moisture content of the panel. In principle, the stiffness properties drop with increasing moisture content within the hygroscopic range. However, swelling provokes closing of open gaps of the middle layers and leads to an apparent increase of stiffness due to internal friction. This increase in stiffness is only relevant for low deflections and can provoke misinterpretation of measuring results when deriving stiffness properties of CLT by means of dynamic methods such as modal analysis. Drying, on the other hand causes cracking within CLT, which manifests itself in a distinct reduction of the bending stiffness perpendicular to the grain direction of the face layers. Calculating bending stiffness of CLT perpendicular to the grain direction of the face layers by means of the compound theory not taking into account the face layers therefore is a common and correct procedure.     

Compression and low velocity impact response of wood-based sandwich panels with auxetic lattice core

European Journal of Wood and Wood Products - The research determined the resistance to compression and low velocity impact of wood-based sandwich panels, the face sheet made of high-density fiber...     

Phenolic content and antioxidant capacity of hybrid variety cocoa beans

Cocoa (Theobroma cacao L.) is a major, economically important, international crop and has been associated with several nutritional benefits including high antioxidant capacity. New cocoa hybrids have been developed in Ghana that exhibit resistance to pest damage during storage. The aim of this work was to assess the phenolic content and antioxidant capacity of these new hybrids in comparison to more traditional cocoa varieties. Total extractable phenolics were similar in all the four hybrids tested ranging from 69.9 to 81.6 FAE g⁻¹. These levels were very similar to that extracted from traditional beans (73.8 ± 2.5 FAE g⁻¹). The “phenolic profile” was determined by HPLC. A total of 25 peaks was observed but there were only minor differences in this profile between traditional and hybrid bean extracts. Antioxidant capacity was determined using the FRAP assay and traditional beans were found to possess 12.4 μmol TE g⁻¹. In comparison the hybrid beans had antioxidant capacities ranging from 21.6 to 45.5 μmol TE g⁻¹, and these were significantly higher than in the traditional beans for three out of the four hybrids. Since the phenolic and antioxidant levels and in these hybrid varieties were either similar to, or higher than, that obtained from traditional beans, the introduction of these new varieties would be unlikely to impact detrimentally on these nutritional components of the beans.     

The effect of yeast extract addition on quality of fermented sausages at low NaCl content

Fermented sausages with 25% or 50% of their NaCl replaced by KCl and supplemented with 1% or 2% concentrations of yeast extract were produced. The sausage production process was monitored with physical, chemical and microbiological analyses. After production, the sausage samples were submitted to a consumer study and their volatile compounds were extracted by solid-phase microextraction and analyzed by GC-MS. The replacement of NaCl by KCl did not significantly influence the physical, chemical or microbiological characteristics. The sensory quality of the fermented sausages with a 50% replacement was poor compared with the full-salt control samples. The use of yeast extract at a 2% concentration increased volatile compounds that arose from amino acids and carbohydrate catabolism. These compounds contributed to the suppression of the sensory-quality defects caused by the KCl introduction, thus enabling the production of safe fermented sausages that have acceptable sensory qualities with half as much sodium content.     

Comparison of a corn silage hybrid with high cell-wall content and digestibility with a hybrid of lower cell-wall content on performance of Holstein cows

We hypothesized that substituting a corn hybrid with high cell-wall content and high neutral detergent fiber (NDF) digestibility (HCW) for a hybrid with lower cell-wall content and lower NDF digestibility (LCW) would improve feed intake and milk production in lactating Holstein cows. There was a 3.6 percentage unit difference in NDF content and a 4.1 percentage unit difference in 30-h in vitro NDF digestion between the 2 corn hybrids. In trial 1, 40 cows (12 primiparous) ranging in milk production from 24.1 to 44.0 kg/d, following a 2-wk preliminary period, were used in a crossover design with 2-wk periods. Diets consisted of 45% corn silage (HCW or LCW), 10% alfalfa hay, and 45% concentrates. The DMI (25.4 vs. 24.2 kg/d) and 4% FCM yield (34.3 vs. 31.7 kg/d) were higher for cows fed the HCW diet compared with the LCW diet. When HCW was substituted for LCW on a DM basis, there was no relationship between pretrial milk yield (preliminary period) and subsequent response to HCW silage. In trial 2, 40 cows (8 primiparous) ranging in milk production from 20.6 to 49.0 kg/d, following a 2-wk preliminary period, were used in a crossover design with 2-wk periods. Diets consisted of the same LCW diet as trial 1 and a diet containing HCW at a concentration (40% of DM) that resulted in equal NDF content (30.8%) between the 2 diets (HCWN). The DMI (26.8 kg/d) was unaffected by diet, although there was a trend for greater DMI (% of BW) for cows fed the HCWN diet compared with LCW silage (4.24 vs. 4.12). Milk fat (3.91 vs. 3.79%) and 4% FCM yield (34.9 vs. 33.4 kg/d) were greater for cows fed HCWN vs. LCW diet. When HCW was substituted for LCW silage on an NDF basis, cows with greater milk production during the preliminary period had a greater milk response to HCW than lower-producing cows. Results of these trials supported our hypothesis that HCW corn silage results in greater DMI and milk yield than LCW silage, whether substitution occurs on a DM or NDF basis.     

Evaluation of the effect of centrifugation using a barycentric method

 The effect of centrifugation of liquid polydisperse systems is determined quantitatively by measuring the resultant displacement of the centre of mass. The physical quantity “specific displacement of the centre of mass” is proposed as a new characteristic of the precipitation of this systems. A device is described which can be used to measure the displacement of the centre of mass of a suspension or emulsion after centrifugation. The advantages of the proposed method and device are pointed out. Received: 18 August 1997 / Revised version: 20 November 1997     

Evaluation of the effect of moisture content on cereal grains by digital image analysis

Physical appearance and kernel morphology significantly affect the grade of a harvested crop in addition to other factors such as test weight, percentage of foreign matter and constituent components. Moisture content of grain can potentially affect the physical appearance and kernel morphology. The objective of this study was to evaluate the effect of moisture content on the classification capability of colour, morphology and textural features of imaged grains. Colour images of individual kernels and bulk samples of three grain types, namely Canada Western Amber Durum (CWAD) wheat, Canada Western Red Spring (CWRS) wheat and barley were acquired using a machine vision system. The grain kernels were conditioned to 12%, 14%, 16%, 18% and 20% moisture contents before imaging. Previously developed algorithms were used to extract 123 colour, 56 textural features from bulk sample images and 123 colour, 56 textural, 51 morphological features from individual kernel images. The extracted features were analysed for the effect of moisture content. Statistical classifiers and a back propagation neural network model were used for classifying the grain bulk at different moisture contents. The colour and textural features of bulk grain images were affected by the moisture content more than that of the single kernel images.     

Establishing tenderness thresholds of Venezuelan beef steaks using consumer and trained sensory panels

The tenderness thresholds for ribeye steaks at 2 d postmortem were found by using sensory trained (n = 734 steaks) and consumers panel data (55 ribeye steaks and 296 consumers). Also, consumers’ perceptions of sensory attributes of beef steaks were assessed to establish their relationships and to determine acceptability levels. The tenderness threshold obtained by regression analysis from trained panelists was 37.98 N (3.87 kg). Customer satisfaction of 81% was obtained when beef steaks had Warner-Bratzler shear force values (WBSF) less than 40.13 N (4.09 kg), suggesting that 40.13 N could be considered as a tenderness threshold to segregate tough from tender steaks, for Venezuelan beef consumers. According to correlation and regression analyses, consumers focused on flavor to assign their overall liking score. Results suggest that consumers are able to detect changes in tenderness of steaks with different WBSF and that flavor drives customer satisfaction when the beef tenderness is acceptable.