The water absorption of sapwood and heartwood of Scots pine and Norway spruce heat-treated at 170 °C, 190 °C, 210 °C and 230 °C

Heat-treatment changes the chemical and physical properties of wood. Wood polymers are degraded, dimensional stability is enhanced, equilibrium moisture content is lowered, colour darkens and biological durability is increased. The properties of heat-treated wood have been researched considerably, but the differences between sapwood and heartwood have not been reported separately. In this research, water absorption differences between sapwood and heartwood of Scots pine and Norway spruce heat-treated at temperatures 170 °C, 190 °C, 210 °C and 230 °C were investigated. The results were compared to industrially kiln-dried reference samples. Water absorption was determined with a floating test based on the EN 927-5 standard. The heartwood of both wood species absorbed less water than sapwood. Heat-treatment evidently decreased the water absorption of spruce and pine heartwood. The higher the heat-treating temperature, the lower the amount of absorbed moisture. However, a very interesting exception was pine sapwood, whose water absorption actually increased with heat-treatment after the three lowest heat-treatment temperatures compared to the reference material. Water absorption did not decrease until the heat-treatment temperature was 230 °C.     

Effect of some metal nanoparticles on the spectroscopy analysis of Paulownia wood exposed to white-rot fungus

The present study was conducted to investigate the effects of impregnation with silver, copper, and zinc oxide aqueous nanofluids on the chemical properties of Paulownia fortunei decayed with the white-rot fungus Trametes versicolor. Wood specimens with a dry density of 0.37 g/cm³ were impregnated with a 400 ppm aqueous suspension of nanoparticles in a pressure vessel under 2.5 bars for 20 min. Specimens were inoculated with the fungus and incubated for 16 weeks at 26 °C and 65 % relative humidity in accordance with EN113. The spectra of specimens impregnated with nanosilver, nanocopper, or nanozinc-oxide showed no significant changes in their relative peak intensities of lignin and carbohydrates after exposure to T. versicolor. This can indicate fungicide effects of the metal nanoparticles on T. versicolor.     

Effect of thermal treatment on the physical and mechanical properties of phyllostachys pubescen bamboo

Thermal treatment of Phyllostachys pubescen bamboo was performed in a dry oven at seven temperature levels (100–220 °C) for four duration times (1–4 h). The results showed that mass loss increased with increasing temperature and duration, and the maximum reduction reached 29.0 %. The color of heat-treated bamboo was darkened and all three color parameters (L^*a^*b^*) were significantly changed. Modulus of elasticity (MOE) was affected slightly when samples were heat-treated below 200 °C, even a slight increase compared with control samples; but it decreased quickly when samples were treated above 200 °C and the maximum reduction was 20.2 %. However, the Modulus of rupture (MOR) and the contents of holocellulose and α-cellulose reduced significantly with increasing temperature and duration when samples were heat-treated above 160 °C, they both strongly correlated with mass loss. It could be confirmed that thermal treatment on bamboo shows an interesting potential to improve bamboo quality.     

Effect of heat-treated <Emphasis Type="Italic">Nuruk</Emphasis> on the quality characteristics of aged <Emphasis Type="Italic">Yakju</Emphasis>

Long-term aging of Yakju, a traditional Korean liquor made of rice and Nuruk (a fermentation agent), causes browning and odor and flavor development. This study investigated the effects of heat-treated Nuruk (50–80 °C, 30 min) on Yakju quality. The saccharogenic powers and glucoamylase, α-amylase, and carboxypeptidase activities were similar in non-heat-treated Nuruk and that treated at 50 °C. However, acidic protease and alcohol dehydrogenase decreased above 50 °C. The content of nitrogen-containing compounds was inversely proportional to the heat-treatment temperature. Compounds that cause off-flavors decreased at 50–60 °C, but increased at 70–80 °C, whereas compounds that provide fragrance increased at 50–60 °C. Sensory evaluation indicated that bad taste attributes were higher in Yakju produced using non-heat-treated Nuruk. Therefore, heat treatment of Nuruk at 50 °C can be adopted as a method for improving Yakju quality, as enzymatic activities that affect color, aroma, and taste are regulated.     

Changes in dimensional stability and mechanical properties of Eucalyptus pellita by melamine–urea–formaldehyde resin impregnation and heat treatment

This study investigated the influence of heat treatment on the dimensional stability and mechanical properties of untreated and low molecular weight melamine–urea–formaldehyde (MUF) resin treated Eucalyptus pellita wood. Wood samples were heat treated under vacuum atmosphere in laboratory conditions at temperatures between 160 and 240 °C for 2–10 h. The results showed that anti-shrink efficiency and anti-swelling efficiency of MUF resin-impregnated heat-treated eucalypt wood were improved by up to 47 and 49 % at 240 °C for 10 h separately, which were greater than those of heat-treated wood. In relation to mechanical properties, the modulus of elasticity and modulus of rupture decreased with increasing temperature and time, but the reduction of properties appeared to be smaller for MUF resin-impregnated heat-treated wood. Therefore, heat treatment combined with resin treatment of eucalypt wood shows potential to improve the wood quality of solid wood products.     

Effect of Konjac Glucomannan (KGM) and Carboxymethylcellulose (CMC) on some Physico-Chemical and Mechanical Properties of Restructured Gilthead Sea Bream (Sparus aurata) Products

The development of restructured fish products and the application of new food ingredients have been used to create attractive new products and also to upgrade low-value species. The aim of this study was to evaluate the effect of konjac gum (KGM) and carboxymethylcellulose (CMC) fibres on the mechanical and physico-chemical properties of microbial transglutaminase treated restructured fish products from gilthead sea bream as well as to evaluate the effect of heat treatment and storage time. Water holding capacity, mechanical properties and colour attributes in fresh and heat-treated samples after 15 days of cold storage were measured. Results showed that these edible gums could be appropriate for making restructured products obtained from gilthead sea bream. In fresh formulations the addition of 10 g?kg^?1 of KGM or 10 g?kg^?1 of CMC presented a significant effect (p?≤?0.05) on water activity for fresh samples and the lowest value was obtained for 10 g?kg^?1 of KGM (0.975?±?0.002). Water holding capacity and adhesiveness increased due to the presence of these gums in fresh and heat-treated samples. For heat-treated samples, KGM significantly reduced (p?<?0.05) hardness, cohesiveness and chewiness. Cryo-scanning electron microscopy revealed different structures for gels containing fibres. The use of these fibres did not induce significant changes in colour parameters. Fresh or heat-treated samples stored for 15 days at 4°C showed changes in relation to the parameters investigated.     

Dimensional stability and creep behavior of heat-treated exterior medium density fiberboard

A series of commercial phenol-formaldehyde bonded MDF panels were exposed to a post-manufacture heat-treatment at various temperatures and durations using a hot press and just enough pressure to ensure firm contact between the panel and the press platens. Physical properties and static flexural strengths of the post heat-treated MDF panels were evaluated according to ASTM D 1037 (2002). The results indicated that the post-manufacture heat-treatment of the exterior MDF panels resulted in improvement of thickness swelling. Water absorption and linear expansion properties were adversely affected by the heat-treatment. Modulus of rupture and modulus of elasticity values of the heat-treated panels decreased with increasing treatment temperature. A series of three 12-week creep tests were performed in climatic chambers conditioned at 65% RH, 90% RH, and cyclic 65–90% RH, all at a steady temperature of 20 °C. The creep tests generally followed procedures as specified in ASTM D 6815-02a (2002). Creep deflections of the panels increased with increasing temperature of the post heat-treatment.     

Mechanical performance and dimensional stability of nano-silver impregnated densified spruce wood

The aim of this study was to investigate the effect of nano-silver treatment on some physical and mechanical properties of compressed low density wood species. Wood specimens were prepared from spruce (Picea abies), impregnated with water or nano-silver solution by empty cell process and compressed through radial direction in a hot press. The results showed that by nano-silver treatment, the spring back, bending strength (modulus of rupture) and impact load resistance were improved significantly. The best results for spring-back (0.04%) were seen in the nano-silver impregnated specimens that were compressed at 150°C for 4 hours. The modulus of rupture (MOR), modulus of elasticity (MOE) and impact load resistance in nano-silver impregnated densified specimens were gained for 53%, 41.2% and 175.7%, respectively (in comparison with controls). The maximum amounts of impact load resistance belonged to the nano-silver impregnated specimens which were compressed at press conditions of 150°C for 4 hours, showing the high ability of these specimens against high impact loads such as earthquake loads. An upcoming research (consisting of durability tests) will be done for evaluating the suitability of nano-silver impregnated densified spruce wood for exterior uses.     

Density and some mechanical properties of densified and heat post-treated Uludağ fir,linden and black poplar woods

The effects of thermo-mechanical densification and heat post-treatment on air-dry density, modulus of elasticity (MOE), bending strength (MOR), and compression strength parallel to the grain (CS) of Uluda? fir (Abies bornmulleriana Mattf.), linden (Tiliagrandifolia Ehrh.), and black poplar (Populus nigra L.) wood samples were investigated. Samples were densified with compression ratios of 25 and 50%, and at 100 and 140?°C. Then, the heat treatment was applied to the samples at 185 and 212?°C for 2 h. According to the results of the study, density of all wood samples increased together with the increase of compression ratio. Regarding compression temperature, the highest density increase was obtained at 100?°C. Mechanical strength (MOE, MOR, and CS) in densified samples increased depending on compression ratio and increase of density. The highest strength increase was in black poplar samples and the lowest was in linden samples. After heat post-treatment, mechanical strength of samples decreased depending on increase in treatment temperature. However, strength values (MOR except) of samples which are 50% compressed and heat-treated were found higher than control samples.     

The properties of Moso bamboo heat-treated with silicon oil

Bamboo is very vulnerable to mold fungi, which greatly limits its applications. In this paper, moso bamboo was heat-treated with silicon oil at temperatures of 160, 175, and 190 °C for a duration of 2 h. The physical–mechanical properties and mold resistance were investigated. The chemical action of silicon oil within bamboo was analyzed by FTIR spectroscopy on bamboo samples before and after the oil heat treatment. The results showed that the hygroscopicity and the dimensional stability of bamboo were effectively improved by the oil heat treatment. The MOR of oil heat-treated bamboo increased as it was treated at 165 and 175 °C due to the oil uptake, but its MOR decreased as the treated temperature increased to 190 °C; at this temperature the degradation of chemical components should be considered. Mold grew more slowly on the oil heat-treated bamboo than untreated bamboo, and the performance of mold resistance was also effectively improved. In addition, the presence and chemical action of silicon oil were also examined through a comparison of FTIR spectrum of untreated control and 175 °C oil heat-treated bamboo.     

Quality Changes and Shelf-Life Prediction of a Fresh Fruit and Vegetable Purple Smoothie

The sensory, microbial, and bioactive quality changes of untreated (CTRL) and mild heat-treated (HT; 90 °C/45 s) smoothies were studied and modelled throughout storage (5, 15 and 25 °C). The overall acceptability was better preserved in HT samples being highly correlated (hierarchical clustering) with the flavour. The sensory quality data estimated smoothie shelf-life (CTRL/HT) of 18/55 (at 5 °C), 4.5/12 (at 15 °C) and 2.4/5.8 (at 25 °C) days. The yeast and mould growth rate was lower in HT compared to CTRL while a lag phase for mesophiles/psychrophiles was observed in HT-5/15 °C. HT and 5 °C storage stabilised the phenolic content. Ferric reducing antioxidant power reported the best correlation (R ² = 0.94) with the studied bioactive compounds, followed by ABTS (R ² = 0.81) while DPPH was the total antioxidant capacity method with the lowest adjustment (R ² = 0.49). Conclusively, modelling was used to estimate the shelf-life of a smoothie based on quality retention after a short-time, high-temperature heat treatment that better preserved microbial and nutritional quality during storage.     

Artificial ageing of softwood joints and its effect on internal bond strength with special consideration of flat-to-end grain joints

The effect of ageing processes on internal bond strength of three-part specimens produced from Norway spruce wood (Picea abies Karst.) bonded with one-component polyurethane (PUR), two-component emulsion polymer isocyanate (EPI), melamine-urea-formaldehyde (MUF) or phenol-resorcinol-formaldehyde (PRF) adhesive was studied. By varying the grain angle of the middle part from 0° (parallel to grain of the surface layers) to 90° (perpendicular to grain of the surface layers) in incremental steps of 10° the effect of grain direction was investigated. The specimens were exposed to a three-step ageing cycle lasting for seven days (50°C/95% relative humidity (rH), ?20°C/65?C70% rH and 75°C/15% rH) which was repeated twelve and twenty-four times, respectively. In general, a decrease in internal bond strength of the exposed specimens was observed. For all tested adhesive systems, influence of ageing processes was more pronounced for flat-to-end grain joints compared to longitudinal joints. For samples bonded with PUR adhesive strength reduction was lower compared to the other adhesives used.     

Effects of high hydrostatic pressure on shelf life of lager beer

Filtered bright lager beer samples were either treated with high hydrostatic pressure (HHP, 350 MPa for 3 and 5 min at 20 °C) or conventional heat pasteurization (60 °C for 15 min). A storage period of 56 days showed that HHP and heat pasteurization had similar results in terms of pH and color (p<0.05). However HHP-treated samples had lower bitterness and protein sensitivity and higher chill haze values than the heat pasteurized samples at the end of the storage period. The microbiological stability of HHP-treated beers was the same as that of heat-treated beers, and the development of both lactic and acetic acid bacteria was inhibited for 56 days of storage. Although more studies should be carried out to investigate the effects of HHP treatment on different types of lagers and ales, our results revealed that HHP could be successfully used to increase the shelf life of beer even at temperatures well below those required for heat pasteurization.     

Effect of Heat-Treatment of Wheat Flour on Pancake Springiness

Pancakes baked with heat-treated wheat flour increased in springiness (recovery from compression) and decreased in gumminess. Brabender Amylograph tests of heat-treated wheat flours (at 120°C for 0, 1.0, 2.0, 3.0, and 5.0 hr) also showed the first viscosity-increase of the flour-water slurries started at lower temperatures when duration of the heat-treatment was increased. The property changes brought about by heat-treatment are consistent with properties of chlorinated wheat flour.     

Inhibited wood degradation of cement-coated beech Laminated Veneer Lumber (LVL) for temporary in-ground applications

This paper investigates the long-term tensile properties of laminated veneer lumber (LVL) beech sections coated with cement and exposed to fungal decay. A set of LVL coupon (dog-bone) samples was stored in compost, tested in tension after 6 and 12 months and compared to reference samples stored at 20 °C and 65% relative humidity. Results showed that after 26 weeks of compost exposure, a fungus of the Ascomycota genus was identified in cement-coated samples using a molecular biology polymerase chain reaction (PCR) technique, which analyses the internal transcribed spacer (ITS) region of the ribosomal DNA. However, no visual deterioration was noticed. Still in cement-covered samples and after 12 months of exposure, a common white rot fungus was determined by DNA chip technology, but no fungal wood decay was visible in areas where the applied coating had a thickness of at least 5 mm. Decay in uncoated LVL samples was significant with the samples having an average residual strength equal to 7%. This compares to the tensile strength of coated samples, which only decreased by 65% relative to the reference samples. Strength and stiffness of coated samples did not differ significantly between 6 and 12 months of exposure. Preliminary investigations tend to show that the strength reduction in cement-coated samples is due to an alkaline degradation of the wood. The observed influence of the coating thickness on the visual fungal decay can probably be ascribed to the protection mechanism due to a physical fungal barrier with a high pH.     

Influence of thermo-vacuum treatment on thermal degradation of various wood species

Solid wood has a certain amount of resistance to fire exposure. Recently, there is also great interest in characterization of the thermal behaviour of treated wood due to increasing demand of such products within the perspective of sustainability of environment. The objective of this study was to evaluate and predict the thermal decomposition process of samples from different wood species, Norway spruce (Picea abies Karst.), common ash (Fraxinus excelsior L.) and Turkey oak (Quercus cerris L.), so that such data can be used for enhanced design of wood products for more effective and better utilization in different applications. Spruce and ash samples were treated at a temperature of 190 °C for 2 h while Turkey oak specimens were steamed at a temperature of 110 °C for 24 h before they were thermally treated at a temperature of 160 °C for 3 h. A thermo-gravimetric analysis of the samples highlighted intraspecific differences in mass loss and the stage of thermal degradation between treated and untreated specimens. The degradation of the wood was characterized by twofold reaction stages, with an exception of Norway spruce samples, which exhibited a one-stage reaction. In addition, thermal treatments affected chemical composition of wood. The obtained results will be helpful in determining the applicability of these materials according to their thermal degradation properties.     

Influence of temperature of thermal treatment on surface densification of spruce

Spruce (Picea abies L. Karst) wood lamellae, thermally treated at 170, 190, 210 and 230 °C were surface densified by compression at a temperature of 150 °C to three degrees of compression. Immediate springback, set recovery, mechanical properties in 3-point flexure, Brinell hardness and density profiles measurements were used to determine the effect of thermal treatment on the properties of surface densified wood. The highest immediate springback occurred in wood specimens thermally treated at the highest temperature (230 °C) and decreased with decreasing thermal treatment temperature. The untreated samples had the highest set recovery, which decreased with the temperature of thermal treatment. The surface densification increased hardness and bending strength. The highest increase was in the case of untreated wood and decreased with the temperature of thermal treatment. The modulus of elasticity (MOE) and modulus of rupture (MOR) of surface densified wood decreased with increasing thermal treatment temperature. The trend was similar for specimens which were thermally treated but not surface densified. Surface densification increased the density of the specimens in the first few millimetres below the surface. The highest density was achieved in untreated specimens and the lowest in specimens thermally treated at the highest temperature.     

Incorporation of bacteriocin in plastic retains activity and inhibits surface growth of bacteria on meat

The bacteriocin, nisin, was incorporated into a polyethylene based plastic film and retained activity against the indicator bacteria Lactobacillus helveticus and Brochothrix thermosphacta . Beef carcass surface tissue sections (BCT) topically inoculated with the psychrotrophic spoilage bacterium B. thermosphacta were vacuum-packaged both with and without wrapping with the nisin impregnated plastic and held at 4° C. An initial reduction of 2 log₁₀cycles of B. thermosphacta was observed with nisin-impregnated wrapped BCT within the first 2 days of storage. After 20 days of refrigerated storage, B. thermosphacta populations from nisin impregnated plastic wrapped samples were significantly less than (P<0·05) control vacuum-packaged samples; log₁₀5·8 vs 7·2 cfu cm⁻²respectively. Temperature abuse was simulated by shifting inoculated packs from 4° C (after 2 days) to 12° C. Again, by 20 days, the B. thermosphacta populations of treated samples wrapped with nisin impregnated plastic were significantly less than (P<0·05) control vacuum-packaged samples; log₁₀3·6 vs 6·3 cfu cm⁻²respectively. This work highlights the potential for incorporating antimicrobial peptides with a wider and different range of inhibitory activity directly into plastics of different properties for use in controlling food spoilage as well as preservation to enhance product microbial safety.     

Effect of oil heating age on colour and dimensional stability of heat treated Pinus radiata

Pinus radiata specimens with moisture content of 8–11% and dimensions of 90×35×200 mm³ were heat-treated in an oil bath of commercial grade raw linseed oil. The effect of oil aging was investigated under treatment condition of 180°C and 3 hours by using oil that had been preheated for 0, 3, 9, 15, 21, and 27 hours, respectively, before the wood treatment. After treatment using oils of varying ages, wood colour change was examined using a Minolta spectrophotometer through CIE 1976 (L ^* a ^* b) system. Water repellent efficiency and anti swelling efficiency in high humidity conditions were measured to determine the stability of the treated wood. The results show that stability of the treated wood was improved significantly compared to the matched untreated wood but the treated wood tended to be darker. Oil viscosity increased with the heating age resulting in slight decrease in weight percentage gain. Water repellent efficiency was decreased with an increase in heating age of oil. However no significant difference in total colour variation and wood stability (anti swelling efficiency) was observed between specimens treated with oils of varying heating age.     

Immobilization of Glucose Isomerase on Radiation-Modified Gelatine Gel

Whole-cell glucose isomerase immobilization on radiation-modified gelatine gel was demonstrated. The enzyme was stabilized within the cells by heat-treatment at 70°C. The heat-treated cells were mixed with radiation-modified gelatine gel and cross-linked by glutaraldehyde. Immobilized enzyme exhibited 70–75% activity as compared to the free cells. Several properties of immobilized glucose isomerase were studied under various reaction conditions. A continuous isomerization was performed using a column packed with cell granules. It has been found, that the half-life of the immobilized glucose isomerase amounted to 650 h at 60°C.