Chemical investigations on boiling process waters in face veneer production

Boiling processes in veneer industry generate large amounts of process water replete with dissolved wood extractives. In the present study the chemical composition of boiling waters from 18 industrially treated wood species were investigated. Contamination levels of the boiling waters varied within a wide range depending on the different extractive contents of the processed wood species and operational conditions. Boiling wood species with high extractives content, heated over several days at temperatures above 80 °C, generate highly loaded waste waters with chemical oxygen demands (CODs) of up to 7000  mg l^-1. The determination of the elemental composition, using optical emission spectrometry (ICP-OES), showed iron contents of up to 10 mg l^-1. Phenolic compounds were in a range of 40 to 900 mg l^-1. Flavonoid compounds and phenolic acids were identified in the boiling waters by liquid chromatography (RP-HPLC-UV). The results confirm the need for water treatment facilities to establish a recycling process and to avoid discolourations of the wood by accumulated wood extractives.     

苹果木烟熏液的品质特性

以苹果木烟熏液为研究对象,从感官品质、pH值、羰基化合物、酚类化合物、苯并（a）芘的含量、挥发性风味物质的组成和电子鼻分析等角度研究苹果木烟熏液的性质,并与目前市场上烟熏液产品进行比较。结果表明,苹果木烟熏液pH值为2.31,酚类化合物、羰基类化合物的含量分别达到9.94 mg/mL和7.91 g/100 mL,挥发性风味物质以酚类物质和醛类为主,相对含量分别为36.15%和17.58%,通过电子鼻主成分分析发现,苹果木烟熏液与其他几种烟熏液之间主成分有显著性差异,与市场其他烟熏液相比,在核心成分和特征性风味物质均有明显的优势,同时无苯并（a）芘检出,表明苹果木烟熏液具有良好的应用前景。     

Air emission from timber drying: high temperature drying and re-drying of CCA treated timber

The nature and mass flows of atmospheric emissions from an industrial kiln, drying radiata pine (Pinus radiata D.Don) timber at 140°C dry bulb and 90°C wet bulb, which was subsequently copper-chrome-arsenic (CCA) treated and redried at 90°C dry bulb and 60°C wet bulb, were assessed by measuring the concentration of chemical components in the kiln atmosphere at regular time intervals and determining air-flows and temperature differentials across the stack. The volatile organic compounds (VOCs) emitted were trapped and analyzed by GC-MS. The two major VOCs found during high temperature pre-drying and CCA re-drying were α-pinene and β-pinene, which made up 87% and 60% of the total discharge (2433 and 145 g/m³ wood), respectively. Most of the VOC fraction was released during the early stages of drying. The polar compounds were trapped in water. Total combined amount of methanol, ethanol, acetic acid and formic acid released over the two runs were 283, 281, 117, and 260 g/m³ wood, respectively. The aldehydes were trapped in 2,4-dinitrophenyl-hydrazine solution and the aldehyde derivatives analysed by HPLC. The total release of formaldehyde and acetaldehyde during the high temperature pre-drying run were 13 and 15 g/m³ wood and the CCA re-drying run were 14 and 4 g/m³ wood, respectively.     

Volatile organic compounds and formaldehyde in nature, wood and wood based panels

The emission of terpene compounds from vegetation is subject to seasonal and diurnal variations. Due to oxidation of terpene compounds simple aldehydes like formaldehyde can be formed. Insofar formaldehyde is an ubiquitous chemical. Due to its high reactivity it has a short half-life time. Wood and wood-based panels emit a low, but still detectable, amount of formaldehyde. The emission depends on exogenic (temperature, relative humidity, air exchange level) and endogenic (wood species, binder level, binder type, production conditions, etc.) factors. With the aging of boards formaldehyde release declines tremendously to reach very low level. Nevertheless, with low fuming binders wood-based panels with formaldehyde emission close to that of untreated wood can be prepared. Non-formaldehyde volatile organic compounds (VOCs) can be released from wood and wood-based panels. The emission rate depends on the wood species as well as on the boundary conditions (drying, storage, etc.). In the case of wood-based panels it depends also on the production factors as well as on the storage conditions. Methods to assess VOCs have been developed and regulations regarding the limits of emission values are under way.     

Ambient air concentrations, source profiles, and source apportionment of 71 different C2-C10 volatile organic compounds in urban and residential areas of Finland

Ambient air concentrations and source contributions of 71 volatile organic compounds (VOCs) including C2-C10 nonmethane hydrocarbons, halogenated hydrocarbons, and carbonyls were studied at urban and residential sites in Finland. On the basis of the emission profile and concentration measurements, the contributions of different sources were estimated using a chemical mass balance (CMB) receptor model. It was shown that it is possible to apply CMB in the case of a large number of different compounds with different properties. However, the performance of the model varies significantly for the different compounds. According to the CMB analysis, major sources for these VOCs at the urban site were traffic and distant sources. At the residential site, the contribution due to traffic was minor while distant sources, liquid gasoline, and wood combustion made higher contributions. However, different compound groups or compounds were found to have totally different sources. It was also shown that a biogenic compound, isoprene, also has significant anthropogenic sources and that at some locations wood combustion can be an important source for some VOCs usually considered as traffic-related compounds (e.g., benzene).     

Comparing the Effects of High Hydrostatic Pressure and Ultrahigh Temperature on Quality and Shelf Life of Cloudy Ginger Juice

The effects of high hydrostatic pressure (HHP) at 500 MPa for 10 min and ultrahigh temperature (UHT) at 110 °C for 8.6 s on the quality of cloudy ginger juice (CGJ) were investigated during storage for 91 days at 4 and 25 °C. The quality aspects studied were microbial stability and selected properties, including pH, total soluble solids (TSS), titratable acidity (TA), total phenols, gingerols, antioxidant capacity, color, and aroma composition. The results showed that HHP treatment led to a 3.0 log cycle reduction of microbial load but did not influence pH, TSS, TA, antioxidant capacity, and color (day 0). Total phenol content increased by 5.31 % after HHP treatment but decreased significantly by 14.74 % after UHT treatment (day 0). Gingerols increased by 14.43 and 14.18 % after HHP and UHT treatments (day 0), respectively. Monoterpenoids, which are the main volatile aroma compounds, did not change significantly after HHP treatment but decreased significantly by 2.27 % after UHT treatment (day 0). During storage, the decreases in total phenols, gingerols, and antioxidant capacity in the UHT-treated GCJ were more noticeable than those in the HHP-treated GCJ. Kinetic data of changes in total phenols, gingerols, and antioxidant capacity fitted into the combined model well. The changes in antioxidant capacity were positively and significantly correlated to total phenols and gingerols. Color darkened and aroma faded in both HHP-treated and UHT-treated CGJs during storage. The quality changes in samples stored at 25 °C were also more noticeable than those stored at 4 °C.     

Phenolic antioxidants in alder smoke during industrial meat curing

Alder wood smoke in a large sausage-curing chamber was analysed with regard to its content of methoxyphenol antioxidants. The use of Tenax adsorbent cartridges permitted simultaneous quantitative sampling of phenols condensed on smoke particles as well as gaseous compounds. The analytical determinations were performed by thermal desorption combined with gas chromatography and mass spectrometry. In addition to methoxyphenols, several other key components were assessed, including 1,6-anhydroglucose, 2-furaldehyde, furans and hydrocarbons. Benzene was the most prominent hydrocarbon. The concentrations of polycyclic aromatic compounds were low, due to a low smoke generation temperature. Predominant smoke components were the 2,6-dimethoxyphenols, which are characteristic thermal degradation products from hardwood. The 2,6-dimethoxyphenols are stronger antioxidants than the 2-methoxyphenols present in lower amounts. The particularly active antioxidants with a 4-alkenyl side-chain constituted 20–30% of total methoxyphenols, which is much more than normally reported for liquid smoke. The phenolic antioxidants may be important not only for the preservation of foods, but also for health as dietary components.     

Influence of chemical modification of wood on the crystallisation of polypropylene

The mechanical properties of wood/polypropylene composites depend strongly on interfacial adhesion between components. However, the application of chemical modification to improve compatibility can influence the supermolecular structure of polypropylene matrix. The experimental material comprised two most common Polish timber species pine wood (Pinus silvestris L.) as a softwood species and beech wood (Fagus silvatica L.) as a hardwood species. The size of wood sawdust ranged from 0.5 to 1.0 mm. Three different types of wood/PP mixture were prepared: (1) PP – untreated wood, (2) PP – NaOH treated wood and (3) PP – esterified wood with maleic anhydride. In this work, the kinetic parameters of crystallization of PP by differential scanning calorimetry were investigated. It is interesting that crystallisation of PP depends on the kind of wood. The chemical treatment of wood caused changes of crystal conversion and half crystallisation time of polypropylene matrix.     

Evaluation of Freshness in Determination of Volatile Organic Compounds Released from Pork by HS-SPME-GC-MS

Freshness is an important parameter for evaluating the quality of pork, which has strong correlation with the characteristic volatile organic compounds (VOCs) in meat. In this study, the pork was stored at a refrigerator, and the VOCs were determined by using headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS). The results of HS-SPME-GC-MS measurements were compared to total viable counts, total volatile basic nitrogen, and pH value to determine possible volatile spoilage markers. The pork was stored in a refrigerator up to 5 days at 4 °C and 466 days at ?18 °C. The pork became stale at 4 °C when the 2,3-butanedione, 3-methyl butyraldehyde, 3-methyl-1-butanol, and acetoin increased to 26.44, 13.72, 71.56, and 340.48 μg/L, respectively. These substances can be seen as characteristic compounds of stale pork. The VOCs such as ethyl acetate, ethyl propionate, ethyl butyrate, and ethyl hexanoate had negative correlation (P?<?0.05) with the pork freshness, which can be potentially considered as characteristic compounds of fresh pork. Therefore, the selected VOCs can be used as indicators for evaluation of pork freshness, and VOCs could be potentially applied in the development of intelligent refrigerators and refrigerated storehouse.     

Design of volatile organic compounds profiles of roasted Coffea arabica extracts produced by supercritical and conventional solvents

This work addresses the potential of supercritical fluid extraction (SFE) to design volatile organic compounds (VOCs) profiles using roasted Coffea arabica. On the whole, 57 VOCs were identified by HS-SPME/GC–MS. A full factorial design was adopted to study the effect of pressure (180 and 300 bar), temperature (40 and 80 °C) and ethanol content (0 and 5 wt.%). The total extraction yield ranged from 1.4 wt.% to 9.8 wt.%. At 180 bar and 80 °C, two extracts exhibited VOCs amount up to 3.5 times higher than the dichloromethane extract. Temperature and pressure favoured VOCs amount and total yield in conflicting ways, and ethanol had a negligible effect on VOCs amount. At 180 bar and 80 °C, the VOCs profile revealed a reinforcement of pyrroles, phenols, cyclopentenes and pyrans, at the expense of pyridines, carboxylic acids and furans. Hence, this essay evidences the potential of SFE to engineer coffee VOCs profiles.     

Antioxidant activity and polyphenol contents in Brazilian green propolis extracts prepared with the use of ethanol and water as solvents in different pH values

Propolis is a natural product with a variable and complex chemical composition associated with its high concentration on polyphenolic compounds. The effect of pH variation (2.0, 3.0, 4.3, 6.0 and 8.0) during aqueous and ethanolic propolis extraction was studied for up to 10 days. Total phenols and flavonoids contents were measured for the extracts by spectrophotometric assays. Antioxidant activity was measured by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and ferric thiocyanate (FTC) methods. The best time of extraction was up to 5 days for all samples. Basic aqueous extracts (pH 8.0) resulted in a higher concentration of compounds than the extract without pH modification, reaching an increase of 160% in flavonoids and 25% in phenols. Ethanolic extracts with pH variation resulted in an extract with 50% less polyphenols and 6% less flavonoids than extract without pH modification. The antioxidant activity was highest for ethanolic extract at pH 4.3 and aqueous extract at pH 8.0 – almost 90% and 45%, respectively, in DPPH method – and was related to the level of polyphenols by Pearson's correlations.     

不同热处理对泡椒挥发性风味化合物的影响分析

目的 研究不同加热处理方式对泡椒挥发性风味的影响。方法 利用气相色谱-离子迁移谱法(gas chromatography-ion mobility spectrometry, GC-IMS)检测分析经煮制、蒸制、炒制和微波加热泡椒样品中挥发性风味化合物的差异性。结果 利用GC-IMS技术从对照组和处理组泡椒样品中共检测出120种主要挥发性风味化合物,其中酯类、醇类、烃类、醛类、酸类和酮类为泡椒中的主要贡献物质,其相对含量占比样品中挥发性有机化合物(volatile organic compounds,VOCs)相对含量的91.76%;经正交偏最小二乘法判别分析(orthogonal partial least squares discriminant analysis, OPLS-DA),筛选出15种可作为区分不同处理泡椒样品中影响VOCs差异性的最关键特征性变量。结论 GC-IMS技术有效地区分出了不同加热处理之后泡椒样品挥发性风味物质的差异性,基于OPLS-DA可全面、客观地对不同热处理泡椒样品进行区分和评价。     

精制杂木木醋液成分分析及其抑菌活性研究

精制杂木木醋液,探讨木醋液成分和再处理后的抑菌活性。通过静置、活性炭吸附相结合法精制杂木木醋液。采用GC-MS(气相色谱-质谱联用仪)技术对精制木醋液进行成分分析。利用滤纸片法测定精制木醋液对大肠杆菌和金黄色葡萄球菌的有效抑菌时间。对精制木醋液进行调pH值、稀释、减压蒸馏、萃取等处理,探讨不同处理方法后木醋液抑制细菌活性的效果。研究结果表明:木醋液对于细菌的有效抑菌时间为24 h;木醋液中的酸性物质影响其抑菌能力;木醋液对细菌的最低抑菌浓度为V精制木醋液:V灭菌水=1:20;60 ℃减压蒸馏抑菌效果最优;萃取木醋液的萃取剂抑菌效果排序为:萃取层>精制木醋液>水层,乙酸乙酯是木醋液的最佳萃取剂。杂木精制木醋液成分主要有酸类、酚类、酮类和醇类等,具有抑菌活性,且再处理后的抑菌活性显著,是一种潜在的生物防腐剂。     

热处理对荔枝果汁品质的影响

为探讨热处理对荔枝果汁品质的影响,将荔枝原果汁在60～100℃温度下进行热处理,测定果汁的褐变度、pH 值、固形物含量、化学成分(糖分、抗坏血酸、5- 羟甲基糠醛(5-HMF)、总酚)及挥发性风味成分等指标的变化。结果表明：荔枝果汁在0～60min 内褐变度的变化符合零级反应动力学模型。热处理过程中抗坏血酸和总酚含量下降明显,而糖含量变化不大,因此抗坏血酸降解和多酚聚合可能是影响荔枝果汁褐变的主要因素。热处理后荔枝果汁风味出现明显变化,采用顶空固相微萃取- 气相质谱对加热前后风味成分进行分析,发现低级醇和酯类含量明显下降,同时,产生了含硫化合物和高级醇等新物质。     

模拟环境中温湿度对卷烟主流烟气化学成分的影响

为了考察温湿度对卷烟主流烟气化学成分的影响,分别于不同温湿度的模拟环境中对卷烟样品进行了抽吸,采用剑桥滤片对主流烟气粒相物进行了捕集,采用XAD-2吸附管和-50℃异丙醇/干冰冷阱串联对气相物进行了捕集,并分析了主流烟气常规化学指标及粒相物和气相物中化学成分释放量变化。结果表明:①卷烟主流烟气常规化学指标主要受环境湿度影响,TPM、焦油和水分均随环境湿度增加而增大,烟气pH随环境湿度增加而减小。②卷烟在不同的模拟环境中抽吸时主流烟气粒相物与气相物中的化学成分种类相同,但同一烟气成分在不同模拟环境中的释放量有明显差异,且不同成分的释放量随模拟条件的变化规律也不同。③粒相物与气相物中的化学成分释放总量都随湿度的增加呈下降趋势;30℃下粒相物中化学成分释放总量明显低于20℃下的释放总量,但气相物中化学成分释放总量随温度的变化趋势不明显。④在粒相物中,醛酮类、酚类、低级脂肪酸和含氮化合物释放总量随湿度增加而降低,高级脂肪酸及其酯的释放总量随湿度增加而升高;在气相物中,芳香烃类、醛酮类、含氮类和有机酸类化合物释放总量随湿度的增加呈下降趋势,烯烃类和酚类化合物释放总量随湿度增加先升高后降低。     

Phenolic compounds in a Spanish red wine aged in barrels made of Spanish,French and American oak wood

A red Rioja wine was aged in barrels made of Spanish oak wood for 21 months. The evolutions of colour percentage intensity, families of phenolic compounds and low molecular weight phenolic compounds were studied in these wines and compared with those of the same wine aged in barrels made of French and American oak. The analysis of chromatic parameters and total anthocyanins indicates that the wines aged in Spanish and French oak wood barrels have similar chromatic characteristics, but are significantly different to those of wines aged in barrels made of American oak wood, indicating a different degree of modification of the colour. The ageing process also had an important influence on the low molecular weight polyphenols composition of wine. The evolution of these components allowed the production of wines with different characteristics, in relation to the type of wood used in barrel making process. On the other hand, Spanish oak wood can be considered suitable for barrel production for quality wines, since a wine aged in barrels made of Spanish oak wood showed similar and intermediate characteristics to those of the same wine aged in French and American oak woods.     

西南桦木材化学成分及其变异的研究

按照我国木材化学成分分析标准,对人工林西南桦木材化学成分进行了测定,结果表明含量分别为:纤维素47.31%,多戊糖23.99%,木质素24.57%,热水抽提物4.41%,1%NaOH抽提物15.15%,笨醇抽提物1.80%,pH值4.61;以上7个指标在树干不同高度的差异均未达到显著性水平;热水、1%NaOH抽提物含量和pH值在不同树龄间的差异达到了1%显著性水平;苯醇抽提物含量达到5%显著性水平.主要化学成分含量的差异不显著.比较分析认为,就木材化学成分而言,西南桦是比较理想的板材和造纸原料.     

Boron fixation in wood: studies of fixation mechanisms using model compounds and maritime pine

The purpose of the research work reported in this paper was to study the kinetics and thermodynamics of reactions of some boron compounds with some simple wood model compounds and with maritime pine (Pinus pinaster Ait.). The wood model compounds were selected in order to reproduce in a simple way the possible reactions boron may undergo with wood. Two boron compounds were tested with the wood: sodium tetraborate decahydrate (borax) and boric acid. Boron containing solutions applied to wood and model compounds were tested in such a way that they could lead to the insolubilization of boron or to its chemical fixation. Thermodynamics of boric acid fixation on the wood surface was studied. Results suggest that, even though boron reacts faster with polysaccharides than with lignin, all reactions are very slow at 20 °C. Adsorption should be the preferential mechanism for the bonding of boric acid to wood. This weak bond explains why boron tends to leach out from wood in wet conditions after conventional preservative treatments.     

完全发酵与适度发酵苹果醋主要成分的差异性分析

研究苹果醋分别采用适度发酵和完全发酵时主要成分及芳香物质种类和含量的差异性。采用福林-酚法、高效液相色谱法、固相微萃取结合气相色谱-质谱联用分别测定2种发酵方式苹果醋中总酚、有机酸含量和芳香成分。结果表明,适度发酵苹果醋总酚含量比完全发酵高21%;2种果醋的有机酸种类完全一致,但适度发酵法中的酒石酸、柠檬酸和富马酸含量更高,而丙酮酸、苹果酸、α-酮戊二酸、乳酸、乙酸和琥珀酸的含量则略低于完全发酵的醋样。适度发酵苹果醋芳香物质种类更丰富,检测到37种芳香成分,其中保留了不少原果香气,如香茅醇、橙花醇、乙酸丁酯、乙酸-4-甲基-3-己酯和乙酸二甲基丁酯等。适度发酵可减少苹果醋总酚的损失,同时保留了更多的苹果原香物质,是值得探索改善苹果醋品质的途径。     

烟熏工艺对熏肉挥发性风味物质的影响

以熏猪肉为对象,研究传统木熏工艺和现代液熏工艺对熏肉挥发性风味物质的影响。对其挥发性风味物质进行GC-MS分析,重点比较两种烟熏方式产品的特色挥发性风味物质的差别。结果表明,传统木熏工艺产品的挥发性风味物质在种类和数量方面都明显高于现代液熏工艺的产品,传统木熏工艺的产品检测出130种挥发性风味物质,而现代液熏工艺检测出121种,酚类物质作为烟熏产品的特色挥发性风味物质,传统木熏工艺的产品检测出15种,含量达到22.85%,而现代的液熏工艺的产品检测出14种,含量仅为7.87%。因此,传统的木熏工艺在风味方面仍然具有一定的优势。