基于智能感官分析的热处理青稞粉滋味品质评价

本实验采用色度仪、电子舌和电子鼻等智能感官仪器,结合感官剖面分析,探究热处理青稞粉滋味品质的差异,结果表明：热处理青稞粉ΔL*下降,色泽向红、黄转移;通过对电子舌、电子鼻数据进行雷达图谱分析和主成分分析（principal component analysis,PCA）,发现不同热处理青稞粉味觉差异显著,味觉以苦味、鲜味和甜味为主,挥发性成分以烷类为主,智能感官分析结果与感官评价结果相一致。     

Heat stability of radio frequency dielectric heat treated low heat and high heat nonfat dry milk

The heat stability of low (LH) and high heat (HH) nonfat dry milk (NDM) that received a radio frequency dielectric heat (RFDH) treatment at 75, 80 or 85 °C for different periods of time (between 43 and 125 min) was assessed. NDM was reconstituted at 3.5% (w/w) protein. Heat stability was assessed at 140 °C by recording the heat coagulation time. Samples were evaluated at native pH, and adjusted pH from 6.4 to 7.2. LH samples heated to 75 °C or 80 °C showed greater heat stability than non-treated LH at pH 6.4 to 6.8. Data suggest that RFDH treatment of LH induced associations between whey proteins and casein micelles, which increased the heat stability in this pH region. The same effect was not observed in the HH samples, suggesting different reactions may be induced. Dry heating NDM may affect protein associations differently from liquid systems, depending upon the conditions.     

Finishing characteristics of heat treated and compressed Rubberwood

The finishing characteristics of heat-treated and compressed Rubberwood were studied. It was found that heat-treated samples had significantly lower finish adhesion strength compared to the conventionally kiln-dried Rubberwood samples, which were used as control specimens. Further, compression of the specimens had also reduced its surface roughness, with an adverse effect on the finish adhesion strength. Inevitably, the use of heat treated and compressed wood in furniture may be suitable for applications, where lower finish adhesion strength could be tolerated at the expense of better finish film quality and process economics, especially in the manufacture of outdoor wooden furniture.     

Chemical changes in hydrothermal treated wood: FTIR analysis of combined hydrothermal and dry heat-treated wood

Wood specimens of Beech (Fagus silvatica L.) and Scots pine (Pinus sylvestris L.) modified by a hydrothermal treatment process were analysed by means of Fourier transform infra red spectroscopy (FTIR). The chemical transformation of the cell-wall material was studied and associated with improved wood qualities. For this purpose, FTIR spectroscopy was used as since this technique has been found appropriate to determine the intensity of specific bonds and functional groups within the polymeric structure. Cleavage of acetyl groups of the hemicellulose has been found to occur in the first treatment step under moist conditions and elevated temperature. This results in the formation of carbonic acids, mainly acetic acid. Most of the acetyl groups were found to be cleaved during the treatment of wood at high temperature, whereas only partial deacetylation was found to occur at moderate treatment temperature. The concentration of accessible hydroxyl groups was measured by acetylation and found reduced after treating at high temperature. Esterification reactions were found to occur under dry conditions at elevated temperature in the curing step, indicated by the increase of the specific ester carbonyl peak at 1740 cm^–1 in the FTIR spectrum. The esters that were formed turned out to be mainly linked to the lignin complex, considering that the newly formed carbonyl groups were found present in heat-treated wood, yet were found to be absent in the isolated holocellulose. Esterification contributes to a decrease of hygroscopicity of wood and consequently improvements of its dimensional stability and durability. However, the role of esterification in the decrease of hygroscopicity in the hydrothermal treatment process examined is believed to be minor compared to the influence of cross-linking reactions known to occur during thermal treatment of wood.

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Veränderungen der Zellwandchemie hydrothermisch behandelten Holzes

Zusammenfassung Das Holz hydrothermisch modifizierten Buchen- und Kiefernholzes wurde mit FTIR Spektroskopie untersucht. Die chemischen Veränderungen wurden mit dem Hintergrund veränderter Holzeigenschaften diskutiert. Abspaltungen von Acetylgruppen der Hemicellulosen finden vor allem bereits im ersten Prozessschritt unter feuchten Bedingungen und bei erhöhten Temperaturen statt. Dieses führt zur Bildung von Essigsäure und anderen Carbonsäuren. Bei niedrigeren Temperaturen werden weniger Carbonsäuren freigesetzt. Durch Acetylierung wurde der Gehalt an freien Hydroxylgruppen bestimmt. Durch die Hitzebehandlung reduziert sich der Gehalt freier Hydroyxlgruppen. Die Zunahme des Carbonylesterpeaks bei 1740 cm^–1 im FTIR Spektrum lässt sich durch Veresterungsreaktionen im heißen aber trocknen Curingschritt erklären. Diese Ester sind vor allem an den Ligninkomplex gebunden und weniger an die Holocellulose. Durch Veresterungen wird ein hygroskopisches, dimensionsstabiles und dauerhaftes Material geschaffen. Die Veränderung der Materialeigenschaften beruht jedoch vor allem auch auf cross-linking Reaktionen die während des Prozesses ablaufen.

     

Bonding performance of heat treated wood with structural adhesives

Bonding of untreated, intermediate (hydro-thermolysed) and heat treated wood with melamine-urea-formaldehyde (MUF), phenol-resorcinol-formaldehyde (PRF) and polyurethane (PUR) adhesives was studied. An industrial heat treatment process (Plato ^®) was used, which included two separate heat treatment stages and a drying stage in-between. Laminated beams having four lamellas were prepared from untreated and treated timber for mechanical testing of the bond lines. The results of the tests showed that heat treatment affected the shear strength and the delamination of the laminated wood depending on the adhesive system used for bonding. The PUR and MUF adhesives performed in a rather similar way, and better than the PRF adhesive. The shear strength of laminated wood bonded with the waterborne MUF and PRF adhesives decreased for the specimens made of hydro-thermolysed timber and decreased further for the specimens made of fully heat treated timber. The difference in adhesive bond shear strength between untreated, intermediate and fully treated wood was less obvious in the case of the PUR adhesive. Delamination of the PRF bond line decreased drastically for all the specimens made of heat treated timber.     

Wood nails to fix softwoods: characterization of structural deformation and lignin modification

Softwoods can be nailed with high density solid wood like Santos Rosewood (Machaerium scleroxylon) or nails made of densified laminated beech wood composite by hammering or shooting, for example with air nail guns, without pre-drilling. Shooting with about 30 m/s causes friction between nail surface and softwood matrix, heating up the interface to temperatures high enough to soften lignin. Re-condensation of softened lignin causes wood welding which doubles pull out strength in comparison to wood nails fixed without wood welding. Changes in lignin UV-absorption within the single cell wall layer and deformation of main anatomical features of spruce wood tissue are characterized by scanning UV microspectrophotometry (UMSP) whereas structural deformations of spruce wood tissue are revealed by X-ray micro-computed tomography (µ-CT).     

A study of strength,hardness and deformation of acetylated Scandinavian softwoods

In this work, properties such as bending strength (expressed as modulus of rupture and modulus of elasticity), hardness, and deformation under cyclic relative humidity have been studied for acetylated Scandinavian pine and spruce. The acetylation was performed with a limited amount of liquid acetic anhydride without addition of catalyst or organic cosolvent. The weight gain due to acetylation was 19.1% for the pine samples. Two kinds of spruce samples were acetylated to 18.2% (narrow annual rings) and 23.3% (broad annual rings), respectively. The results indicated that only small changes in strength were obtained. For pine, modulus of rupture decreased with about 6%, and increased with about 7% for spruce. The modulus of elasticity also decreased for pine but increased for spruce. For practical applications, these properties can be considered unaltered. Acetylated pine wood showed increased Brinell hardness. Acetylated spruce wood did not tend to deform as much as unmodified wood when exposed to moisture cycled between 40 and 90% relative humidity     

Composition of volatile compounds in bovine milk heat treated by instant infusion pasteurisation and their correlation to sensory analysis

Volatile compounds in skim milk and nonstandardised milk subjected to instant infusion pasteurisation at 80°C, 100°C and 120°C were compared with raw milk, high temperature short time pasteurised milk and milk pasteurised at 85°C/30 s. The composition of volatile compounds differed between infusion pasteurisation treated samples and the reference pasteurisations. The sensory properties of skim milk subjected to instant infusion pasteurisation were described by negative attributes, such as cardboard sour and plastic flavours, which are not associated normally with fresh milk. Partial least squares modelling showed good correlation between the volatile compounds and the sensory properties, indicating the predictive and possible causal importance of the volatile compounds for the sensory characteristics.     

Chemical composition and in-vitro digestibility of thermochemically treated peanut hulls

Changes in chemical composition and digestibility of peanut hulls after a variety of thermochemical treatments were monitored. Mineral acids and base under elevated temperature (121°C) were generally ineffective for decreasing the fibrous, lignocellulosic component of the hulls. Only nitric acid-treatment effectively decreased the relative lignin content of the hulls. The lignin:nitrogen ratio and carbohydrate content of treated hulls were both highly correlated with in-vitro digestibility. Overall, thermochemical treatments did not increase the digestibility of peanut hulls.     

棉纺织品损伤的化学分析

纺织品在加工及后整理过程中会受到各种损伤，这些损伤产生的原因可用不同的化学方法进行测定．粘度法测定聚合度、针头反应可测定损伤发生的程度，而损伤产生的原因可通过Fehling溶液、乳酸酚蓝试剂及红，绿测试方法进行分析．     

羊毛损伤的化学分析

羊毛在生产加工和后整理的过程中会受到各种损伤,从而影响到产品质量,因此测定损伤产生的真正原因具有重要的现实意义.着色试验法是用各种着色剂来测试受损羊毛,根据得色量来判断羊毛受损伤的程度;泡利反应法是利用泡利试剂与受损羊毛反应后生成物的颜色深浅来判断羊毛的受损情况,可以初步判断是机械损伤、化学损伤还是生物损伤;.KMV法可测试羊毛的酸、碱损伤程度;生物测试法可分析羊毛受到的细菌损伤或真菌损伤.这些损伤分析方法是羊毛质量控制的重要组成部分,对质量保证起到重要作用.     

原料乳热处理条件对Mozzarella干酪品质的影响

采用3×3拉丁方试验设计,3个奶酪槽中原料乳热处理条件分别设为未杀菌,63℃(30min)杀菌,72℃(15s)杀菌。研究干酪加工中原料乳热处理条件对Mozzarella干酪的品质的影响。结果表明,未杀菌乳制干酪的蛋白水解、硬度及弹性与杀菌乳制干酪的蛋白水解、硬度及弹性值具显著差异(p<0.05),未杀菌乳制干酪的蛋白水解显著增加,弹性及硬度显著降低;63℃(30min)及72℃(15s)不同杀菌温度处理的乳制得的干酪之间蛋白水解、硬度及弹性无显著差异;不同热处理乳制干酪之间的融化性和油脂析出性在统计学上无显著差异。     

Physicochemical properties of pressure moisture treated (PMT) and heat moisture treated (HMT) starches

Physicochemical properties of pressure moisture treated (PMT, 550 MPa, 10 min) and heat moisture treated (HMT, 100 °C, 10 h) starches were investigated. Effects of PMT and HMT were different depending on starch type. PMT starches showed dramatic changes in moisture sorption isotherm, pasting properties, thermal characteristics, solubility and swelling power (at 90 °C), and in vitro digestibility. The most dramatic difference between PMT and HMT starches was amylopectin melting transition, i.e., broadening in PMT and shift to high temperature in HMT starches. Moreover, B- and C-type starches revealed the more increase in amylopectin melting enthalpy than A-type starch. Both PMT and HMT did not increase the crystallinity but reorganized the amorphous area to compact, resulting in lower rapidly digestible starch and higher slowly digestible starch than those of native starches. Consequently, PMT changed the digestibility and physicochemical properties of starches with different modes of action compared with HMT.     

高温花生粕中花生蛋白提取工艺研究

采用碱溶酸沉法,并结合匀浆、超声和纤维素酶等前处理从高温花生粕中提取花生蛋白。由正交回归实验得到碱溶酸沉提取最佳条件为:碱溶温度为60℃、pH9.5、料液比1:8(m/v),在此条件下搅拌浸提120min后,提取率为64.2%。匀浆或超声前处理均可增加蛋白提取率,超声处理后提取率增加尤为显著,提高了12.3%,而纤维素酶前处理则对提取率无显著作用。     

Comparison between heat treated sapwood and heartwood from Pinus pinaster

Sapwood and heartwood samples of Pinus pinaster were treated in an oven at 190 and 200 °C for 2–6 h. Dimensional stability, measured as Anti Shrinking Efficiency (ASE) between 0 and 65 % relative humidity, durability against fungi, mechanical resistance (MOE and MOR), hardness and chemical composition were determined for treated and untreated sapwood and heartwood. Radial ASE reached 52 % for sapwood and 50 % for heartwood, while tangential ASE reached 50 and 40 %, respectively. MOE increased slightly at the beginning of the treatment, decreasing afterwards. No significant differences were found between sapwood and heartwood. MOR decreased by 50 and 30 % for sapwood and heartwood, respectively. A significant increase in durability against Rhodonia placenta was found for both heartwood and sapwood at the higher temperature (200 °C), but at the lower temperature (190 °C) only heartwood showed good results.     

Aroma development in high pressure treated beef and chicken meat compared to raw and heat treated

Chicken breast and beef muscle were treated at 400 and 600 MPa for 15 min at 5 °C and compared to raw meat and a heated sample (100 °C for 15 min). Vacuum-packed beef meat with a smaller fraction of unsaturated fatty acids showed better oxidative stability during 14 days of cold storage, as shown by a low steady-state level of hydroperoxide values, than vacuum-packed chicken meat. Accordingly, the critical pressures of 400 MPa and 600 MPa for chicken breast and beef sirloin, respectively, were established. Volatiles released after opening of the meat bags or during storage of open meat bags, simulating consumer behaviour, were measured under conditions mimicking eating. Quantitative and olfactory analysis of pressurised meat gave a total of 46 flavour volatiles, mainly alcohols (11), aldehydes (15), and ketones (11), but all in low abundance after 14 days of storage. Overall, beef meat contained less volatiles and in lower abundance (factor of 5) compared to chicken meat. The most important odour active volatiles (GC-O) were well below the detection thresholds necessary to impart a perceivable off-flavour. Lipid oxidation was significantly accelerated during 24 h of cold storage in both cooked chicken and beef when exposed to oxygen, while the pressurised and oxygen-exposed chicken and beef meat remained stable. Pressure treatment of beef and chicken did not induce severe changes of their raw aroma profiles.