热加工对大蒜、洋葱及生姜化学成分和抗氧化能力影响

以大蒜、洋葱及生姜为原料研究其在加热过程中化学成分和抗氧化能力的变化。结果表明:在课题组前期优化得到的最佳工艺参数75℃、85%湿度恒温恒湿箱中热加工8 d后,六种形态大蒜、洋葱及生姜的水分含量都迅速减少、色泽变深,还原糖、总糖、总酸、蛋白质等营养成分含量较热加工前都有升高,多酚含量也增加。热加工后三种辛香蔬菜的抗氧化能力都有不同程度的增加,其中生姜的还原能力、清除羟基自由基能力、清除超氧阴离子自由基能力以及清除DPPH自由基能力增幅最大,分别增加了2.5倍、8.5倍、3.2倍、4.6倍。      

日本落叶松热处理材表面显微硬度变化研究

以过热蒸汽为传热介质和保护性气体,在热处理温度为165℃、180℃、195℃、210℃,热处理时间为10h的条件下对日本落叶松木材进行高温热处理,研究日本落叶松木材在不同热处理温度下的表面显微硬度变化。结果表明,随着热处理温度升高,热处理材表面显微硬度逐渐升高,当热处理温度低于195℃时,木材表面显微硬度变化趋势不明显,当热处理温度达到210℃时,热处理材的表面显微硬度显著提高,变化率高达44.12%。     

Effect of yeast antagonist in combination with heat treatment on postharvest blue mold decay and Rhizopus decay of peaches

The potential of using heat treatment alone or in combination with an antagonistic yeast for the control of blue mold decay and Rhizopus decay of peaches caused by Penicillium expansum and Rhizopus stolonifer respectively, and in reducing natural decay development of peach fruits, as well as its effects on postharvest quality of fruit was investigated. In vitro tests, spore germination of pathogens in PDB was greatly controlled by the heat treatment of 37 degrees C for 2 d. In vivo test to control blue mold decay of peaches, heat treatment and antagonist yeast, as stand-alone treatments, were capable of reducing the percentage of infected wounds from 92.5% to 52.5% and 62.5%, respectively, when peach fruits stored at 25 degrees C for 6 d. However, in fruit treated with combination of heat treatment and Cryptococcus laurentii, the percentage of infected wounds of blue mold decay was only 22.5%. The test of using heat treatment alone or in combination with C. laurentii to control Rhizopus decay of peaches gave a similar result. The application of heat treatment and C. laurentii resulted in low average natural decay incidences on peaches after storage at 4 degrees C for 30 days and 20 degrees C for 7 days ranging from 40% to 30%, compared with 20% in the control fruit. The combination of heat treatment and C. laurentii was the most effective treatment, and the percentage of decayed fruits was 20%. Heat treatment in combination with C. laurentii had no significant effect on firmness, TSS, ascorbic acid or titratable acidity compared to control fruit. Thus, the combination of heat treatment and C. laurentii could be an alternative to chemicals for the control of postharvest decay on peach fruits.     

Effect of heat treatment duration on the thermal conductivity of spruce and poplar wood

Changes in the thermal conductivity and density of Pannónia poplar (Populus x euramericana cv. Pannónia) and spruce (Picea abies) caused by heat treatment were examined. The specimens were treated at 180?°C for 15, 25 and 35 h. Treatment duration had different impact on both the density and the thermal conductivity of poplar and spruce. The density of poplar decreased by 9.1, 12.1 and 13.4%, and the thermal conductivity decreased by 16.9, 24.0, 29.1% after 15, 25 and 35 h of treatment, respectively. In the case of spruce, the density decreased by 5.2, 7.6 and 8.7%, and the heat conductivity by 7.4, 14.1 and 22.0%, respectively.     

微波处理强度对不同产地烟叶化学成分及感官质量的影响

采用改变微波功率、作用时间的方式,对不同地区的烟叶进行微波松散,测定松散前后总糖、总氮、植物碱、氯、钾含量,并进行对比评吸。结果表明,随着微波处理强度的加大,烟叶总糖含量呈现先升高后降低的趋势,总氮、植物碱略有降低,氯和钾含量无明显变化;较低处理强度对香气质、干净程度、细腻程度、杂气指标有一定的改善作用,但较高的处理强度对香气量、浓度有不利影响,对甜度和回味影响不明显。     

Effect of filtered wood smoke treatment on chemical and microbial changes in mahi mahi fillets

ABSTRACT:  A study was performed to investigate the effect of filtered wood smoke processing on quality and safety of mahi mahi compared to no treatment. Skinless mahi mahi fillet portions were either treated with filtered smoke (FS) or left untreated for 24 h, followed by either (a) aerobic storage at 4 °C for 8 d or (b) freezing for 30 d (–25 °C) followed by thawing and aerobic storage at 4 °C for 8 d. Results show that treating mahi mahi fillets with FS increased ( P < 0.05) a * values (redness) of the muscle and stabilized it during frozen storage. The redness did, however, decay ( P < 0.05) rapidly on cold storage for both defrosted and fresh filtered-smoke-treated products, and reached initial (presmoking) redness levels in 2 d. The FS process overall significantly ( P < 0.05) improved microbial stability of the product. Stability toward lipid oxidation was also significantly ( P < 0.05) increased for the FS products compared to untreated products, particularly after defrosting. Sensory studies supported the microbial and lipid oxidation findings, showing that products treated with FS were better accepted and had increased ( P < 0.05) shelf life over the untreated products. The shelf life was, however, compromised when microbial levels increased; that is, the process did not mask microbial spoilage; the spoilage did become evident in the sensory trials.     

木材热处理研究的进展

介绍了木材热处理技术在国内外的研究进展情况,并对该项技术的发展进行了展望。     

纤维化学组分对再生植物纤维品质衰变影响的研究

通过选择性的脱除纤维细胞壁中的半纤维素和木素,研究半纤维素和木素含量对再生植物纤维品质衰变的影响.研究结果表明:随着半纤维素含量的减少,再生植物纤维的保水值降低,结晶度增加.当半纤维素含量从27.62%降至9.09%时,保水值下降了41%,纤维素结晶度从1.011增加到1.514.半纤维素含量与再生植物纤维成纸性能的变化有明显的线性相关性.较高含量的半纤维素可以缓解回用过程中再生植物纤维成纸性能的损失.同时发现木素对再生植物纤维性能的影响很小.木素含量与纤维的保水值、结晶度与成纸性能的变化没有明显的线性相关性.     

Effect of essential oil compounds and plant extracts on decay and termite resistance of wood

Essential oils and their derivatives have a long history of safe usage as antimicrobial agents in food industry. In this study various essential oils and extracts from plants were screened for their ability to inhibit wood decay and termite attack in laboratory decay and termite resistance tests using treated wood specimens. In the laboratory decay resistance tests, wood specimens treated with essential oil compounds were subjected to brown-rot fungus, Tyromyces palustris, and white-rot fungus, Trametes versicolor for three months. The specimens were also subjected to termite attack by subterranean termites, Coptotermes formosanus for three weeks in laboratory conditions. The formulation with cinnamaldehyde (DF3) was found to be effective against both the brown-rot and white-rot fungi used in the study. However, the formulation with cinnamic acid (DF8) was able to protect wood specimens against only the white rot fungus and about 50% mass loss occurred in the specimens subjected to the brown-rot fungus. The mass losses in the wood specimens treated with cassia oil containing formulation (DF4) showed that cassia oil was effective against both fungi. The wood tar oil and dodecanal compounds also inhibited fungal decay in the specimens. The wood specimens treated with the formulations used in termite resistance tests were more resistant against the termites when compared to specimens treated with the formulations in decay resistance tests. Even after severe weathering process, treated wood specimens showed resistance against the subterranean termites. Results suggest that essential oils and plant extracts might be important to develop new wood preservatives that are less harmful to the environment and humans than recently available ones.     

pH对蓝莓果化学组分影响研究

本实验以蓝莓果为原材料,采用GC-MS柱前衍生化法对蓝莓果提取液中的化学组分进行动态监控,并探究p H3.0⁹.0对其的影响。结果表明:蓝莓果提取液中共鉴定出39种化合物,包括糖类、酸类、醇类、酯类和酮类五大类,其中糖类、酸类和酯类化合物总含量随着p H由酸性变为碱性呈减少的趋势,而醇类化合物的总含量和肌醇单酮含量呈增多的趋势,并且发现在p H7.0⁹.0产生了新物质阿拉伯呱喃糖,其含量随p H升高逐渐增大;通过对蓝莓果提取物中含量较高的糖类化合物和酸类化合物进行动态监控,发现酸类化合物随着p H由酸性到碱性含量呈减少的趋势,而葡萄糖和阿拉伯呱喃糖随着p H的增大含量呈增多的趋势。实验结果对于蓝莓资源受p H影响的深加工技术提供一定的理论依据。      

Changes in the properties of light-irradiated wood with heat treatment

This study investigated the changes in the color of wood with heat treatment after exposure to light at various conditions. The change with exposure is attributed to the decomposition of lignin, and the process follows a first-order reaction law. The degree of color change in softwood was greater than in hardwood, while there was no significant difference between the reaction rates for softwood and hardwood. This is attributed to differences in the lignin content. The change in the color of light-irradiated wood with heat treatment increased with light-irradiation time, heating temperature, while the changes in the color of wood irradiated for more than 30 to 40 h were similar. With the investigation of the effect of wavelength, the change in the lightness, L*, of all the woods tested decreased with wavelength. L* became positive for light-irradiated Japanese cypress and hackberry; however, this effect disappeared with heat treatment. The chroma coordinates a* and b* of all species were minimal when irradiated with wavelengths longer than 500 and 440 nm, respectively. However, this effect disappeared with heat treatment. In softwood, b* was negative when exposed to light longer than 440 nm, while in hardwood, it turned negative when exposed to 390, 440, and 500 nm. However, the minimum value observed with light-irradiation disappeared with heat treatment after light-irradiation. Therefore, it is thought that chemical changes involved in the color changes due to light-irradiation differ form those involved in the color changes due to heat treatment.

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Veränderung der Eigenschaften von Licht-bestrahltem Holz nach HitzebehandlungTeil 2: Einfluss von Bestrahlungszeit und Wellenlänge

Zusammenfassung Die Farbänderungen von Holz durch Hitzebehandlung nach Lichtbestrahlung unter verschiedenen Bedingungen wird untersucht. Die Farbänderung wird auf Ligninabbau zurückgeführt. Der Prozess folgt einer Reaktion 1. Ordnung. Das Ausmass der Farbänderung war bei Nadelholz größer als bei Laubholz, während die Reaktionsraten keine signifikanten Unterschiede aufwiesen. Dies wird auf Unterschiede im Ligningehalt zurückgeführt. Die Farbänderung der Licht-bestrahlten Proben nach Hitzebehandlung verstärkt sich mit der Bestrahlungszeit und der Temperatur der Hitzebehandlung; nach Behandlungszeiten von mehr als 30 bis 40 Stunden gleichen sich die Farbänderungen jedoch an. Auch der Einfluss der Wellenlänge wurde untersucht. Dabei erhöhte sich die Helligkeit, L*, bei allen Proben mit der Wellenlänge. L* wurde positiv für japanische Zypresse und Zürgelbaum; allerdings verschwand dieser Effekt nach Hitzebehandlung. Die Koordinaten a* and b* waren bei allen Proebn minimal, wenn mit Wellenlängen >500 bzw. >440 nm bestrahlt wurde. Auch dieser Effekt verschwand nach Hitzebehandlung. Bei Nabelholz war b* negativ nach Bestrahlungen mit Wellenlängen von 390, 440 und 500 nm. Die beobachteten Minima verschwanden allerdings nach der anschließenden Hitzebehandlung. Daraus ergibt sich, daß die chemischen Veränderungen aufgrund der Bestrahlung anderer Art sind als die durch Hitzebehandlung verursachten.

     

The influence of spruce wood heat treatment on its thermal stability and burning process

This paper deals with the assessment of the influence of heat treatment of Norway spruce wood (Picea abies L.) on its thermal stability and burning process. Three types of samples were used for the research. The first group was comprised of untreated samples. The second group was comprised of samples heat treated according to the ThermoWood—Thermo-S thermal programme (maximum temperature during heat treatment is 190 °C), and the third group was modified according to the ThermoWood—Thermo-D thermal programme (maximum temperature during heat treatment is 212 °C). The influence of heat treatment on the burning process was assessed based on the heat release rate, effective heat of combustion and the yield of carbon monoxide. The influence of heat treatment on the thermal stability was assessed based on the resistant residue weight. Heat release rate, effective heat of combustion, yield of carbon monoxide and resistant residue weight were determined with a cone calorimeter for different heat flux densities. The results obtained prove that the spruce wood heat treatment has an important influence on the decrease of the maximum heat release rate and the increase of resistant residue weight. The results obtained further prove that the heat treatment has only a modest influence on the increase of the carbon monoxide yield, and its influence on the effective heat of combustion significantly depends on the heat flux density.     

热处理方式对南美白对虾虾青素含量、氨基酸组成及脂肪酸组成的影响

热处理是南美白对虾的重要加工手段,本文通过研究蒸制和煮制对南美白对虾含水量、虾青素含量、氨基酸组成及脂肪酸组成的影响,探索不同的热处理方式对南美白对虾营养成分的影响。结果表明:蒸制和煮制均导致南美白对虾含水量降低;蒸制较煮制的南美白对虾具有更高的虾青素含量,蒸制6 min时虾青素含量最高,达58.00μg/g;蒸制和煮制后总氨基酸含量均明显提高(p<0.05),蒸制样品中的苏氨酸、缬氨酸、亮氨酸、异亮氨酸、苯丙氨酸、蛋氨酸等必需氨基酸含量均高于煮制样品;蒸制和煮制后单不饱和脂肪酸含量降低,而多不饱和脂肪酸含量则分别由鲜虾的33.32%增加到煮制样品的35.13%和蒸制样品的35.02%。因此,蒸制是南美白对虾的一种良好的热处理方式。      

Effect of ethanol in feed on milk flavor and chemical composition

A crossover study was performed using 24 dairy cows to investigate whether pure ethanol in concentrations that could be found in well-fermented silages influenced milk composition or flavor. Cows were fed a standard ration of well-fermented grass silage for ad libitum intake and high moisture barley and a protein concentrate in restricted amounts. A daily dose of ethanol (600 g) was divided into three meals/d and fed with grass silage. When cows received ethanol, milk yields decreased slightly, but milk fat and protein concentrations increased so that energy-corrected milk yield increased by 0.9 kg/d. Milk concentrations of lactose and urea decreased, concentrations of ethanol and acetone increased, concentrations of free fatty acids increased slightly, and alpha-tocopherol concentrations were unaffected. The proportion of palmitic acid in milk fat increased, and the proportion of unsaturated acids decreased. Organoleptic milk quality was reduced because of an increase in milk tainted by feed flavors. The off-flavor could not be attributed solely to the ethanol transmitted to the milk. Precautions should be taken to avoid extensive production of ethanol during fermentation of grass silage and other feeds that are to be fed to dairy cows.     

Effect of chemical treatment on the fatty acid composition of european cucumber fruit during cold storage

Mature green European cucumber fruits (Cucumis sativus L. cv. ‘V-5’), grown in the greenhouse, were treated with butylatedhydroxytoluene (BHT) and calcium chloride, stored at 4°C for 7 days and transferred to 20°C for another 7 days. There were no visible symptoms of chilling injury on cucumbers during cold storage, but surface pitting and shrinking started 2 days after fruits had been transferred to 20°C. Total lipid content was not affected by chilling or chemical treatment, but changes in the lipid classes were observed. Neutral lipids were increased and phospholipids decreased. Laurie and myristic acids were decreased by chilling and chemical treatment, and palmitic acid increased in each lipid class with BHT treatment. Linoleic acid was increased by CaCl₂ treatment in each fraction. Linolenic acid response varied with chilling and chemical treatment. The unsaturation ratio of 18-carbon acids was increased for total lipids and phospholipids.     

微波和红外处理对油茶仁油组成和稳定性影响规律

通过微波和红外两种方式加热油茶籽,研究了油茶仁的水分、含油率以及压榨油茶仁油的水分、氧化稳定时间、分子质量组成、液质成分等的变化规律.研究结果表明,微波和红外加热均可有效去除油茶仁和油茶仁油中的水分,相比油茶仁随加热强度增大水分降低的规律,油茶仁油中水分在加热后期有略微上升.不同功率微波处理油茶籽后,油茶仁油的氧化稳定...     

The comparison of chemical and structural differences of Caribean pine (Pinus caribea L.) wood and bark lignin

The presented paper deals with some chemical properties of Caribean pine wood and bark lignin. In order to obtain necessary data, the following operations and analyses were performed: dioxane lignin isolations, determination of Klason lignin, determination of methoxyl, carboxyl and phenolic hydroxyl groups in dioxane lignins and the nitrobenzene oxidation of both compared lignins and of the risidues remaining after dioxane lignins extraction. The oxidation products were analysed by GLC. The experimental data show that there are moderate differences between compared lignins.