Aroma volatile compounds from two fresh pineapple varieties in china

Volatile compounds from two pineapples varieties (Tainong No.4 and No.6) were isolated by headspace solid phase microextraction (HS-SPME) and identified and quantified by gas chromatography-mass spectrometry (GC/MS). In the Tainong No. 4 and No. 6 pineapples, a total of 11 and 28 volatile compounds were identified according to their retention time on capillary columns and their mass spectra, and quantified with total concentrations of 1080.44 μg·kg(-1) and 380.66 μg·kg(-1) in the Tainong No.4 and No. 6 pineapples, respectively. The odor active values (OAVs) of volatile compounds from pineapples were also calculated. According to the OAVs, four compounds were defined as the characteristic aroma compounds for the Tainong No. 4 pineapple, including furaneol, 3-(methylthio)propanoic acid methyl ester, 3-(methylthio)propanoic acid ethyl ester and δ-octalactone. The OAVs of five compounds including ethyl-2-methylbutyrate, methyl-2-methylbutyrate, 3-(methylthio)propanoic acid ethyl ester, ethyl hexanoate and decanal were considered to be the characteristic aroma compounds for the Tainong No. 6 pineapple.     

吉林靖宇地区4个蓝莓品种酿酒特性研究

为探究吉林靖宇地区“北陆”“、普蓝51号”“、美登”“、北春”4个蓝莓品种的酿酒特性,对其3个形态指标、9个理化指标进行测定,运用相关性分析与主成分分析（PCA）方法对蓝莓酿酒特性进行综合评价。结果表明,不同品种间各项指标存在差异与相关性“,北春”果粒稍小,可溶性固形物和单宁含量显著高于其他3个品种（P<0.05）、总酸含量显著低于其他3个品种（P<0.05）,固酸比最高,达到52.2。对蓝莓果实及酒指标进行主成分分析,影响酒质的主要指标依次为果实总酸、酒单宁、果实可溶性固形物、酒总花色苷及酒总酸含量5个指标,对不同蓝莓品种酿酒品质相关性状进行综合得分分析并进行排名,表明蓝莓品种“北春”得分最高,酿造的酒品质最好。     

砾石对赣北红土工程锥状堆积体侵蚀规律的影响

以赣北红土为研究对象,通过组合不同砾石质量百分数(0%、10%、20%、30%)、不同降雨强度(1.0、1.5、2.0、2.5mm/min)的室内模拟试验,对开发建设项目中散乱锥状堆积体的产流产沙规律进行研究。结果表明,在相同降雨强度下,含砾石堆积体(10%、20%、30%)的产流时间要明显小于不含砾石堆积体(0%)的产流时间;砾石对径流率的影响不明显,但径流率与降雨强度有明显的正相关关系;在降雨强度≥1.5mm/min的条件下,四种砾石含量堆积体的侵蚀速率在一场60min的降雨中主要经历"浮土冲刷"、"形成结皮"、"可蚀性泥沙减少"和"结皮破坏"四个阶段;一场降雨后堆积体总产沙量随砾石质量百分数的变化依次为0%10%20%30%,砾石能够促进堆积体的坡面侵蚀。     

酶法快速测定植物油中游离甾醇

目的 基于甾醇在胆固醇氧化酶的作用下与显色剂产生显色反应,建立了固相萃取结合酶法测定植物油中游离甾醇含量的快速检测方法。方法 采用固相萃取（Solid Phase Extraction, SPE）结合酶法40 min内实现对植物油中的游离甾醇含量测定,并应用于植物油中游离甾醇含量的测定。结果 方法学验证的结果显示,植物甾醇含量在浓度范围0.3~7.5 mg/mL之间线性良好,检出限为0.018 mg/g,日内精密度为7.94%,日间精密度为6.88%,回收率在84.75%~99.50% 之间,实际样品的检测结果显示,酶法与气相色谱-串联质谱法（gas chromatography-tandem mass spectrometry, GC-MS）的相对误差在±20%以内,且酶法的检测效率比GC-MS法提高3倍。常见的几种植物油中,游离甾醇含量较高的是玉米油和菜籽油,分别为1.53~3.66 mg/g和1.98~3.02mg/g。结论 本研究建立的SPE结合酶法检测植物油中游离甾醇的快速检测方法稳定性、重现性好、灵敏可靠,可满足植物油中游离甾醇的现场批量快速检测。     

电子自旋共振波谱法检测含骨类食品的初步研究

电子自旋共振(Electron spin resonance,ESR)波谱测定是检测含骨类食品自由基的有效方法之一.本工作研究了辐照诱导的含骨类食品的ESR波谱特征、样品制备方法及辐射剂量-效应关系.结果表明,辐照前后ESR波谱图形、g因子和△H皆有明显差异,据此很容易区分辐照与未辐照含骨类食品样品;冷冻干燥和磨碎是样品制备过程中的关键步骤;吸收剂量(0.3-10.1kGy)与ESR信号强度有良好的线性关系;ESR信号的相对强度还与动物种类有关.这为制定我国含骨类辐照食品的ESR检测方法标准提供了依据.     

Transient burn-out in liquid helium with rapid rise of heat flux

This Paper presents the results of experimental and theoretical investigations of transient burn-out in liquid helium moving freely. Heat input in the open vertical channel with liquid helium was increased linearly. The rate of increase of heat flux was varied from 100 to 23 000 W m⁻² s⁻¹, ensuring both quasi-steady and transient conditions. When heat input rose rapidly, burn-out simultaneously appeared over the entire channel length. This can be explained by the peculiarities of unsteady hydrodynamics. A physical model of transient boiling burn-out in a pool and in channels is presented. Relationships for some forms of heat flux variation in time have been derived on the basis of this model. Present experimental data and results of other authors are verified by means of the developed model.     

Ethanol production from agroindustrial biomass using a crude enzyme complex produced by Aspergillus niger

This study investigates ethanol production from simultaneous fermentation and saccharification (SFS) and separated hydrolysis and fermentation (SHS) using enzyme complexes produced by Aspergillus niger strains (ATCC 16404, ATCC 1057, ATCC 9029). The enzyme complexes were produced by solid-state fermentation (SSF) on inexpensive and readily available agroindustrial products: rice byproduct (composed of AFEX-treated rice rust and rice bran), whey and sugarcane bagasse. The ethanol was produced by Saccharomyces cerevisiae Y904 using whey and rice byproduct as the substrate and the enzyme complex produced by A. niger. The best result for solid-state fermentation (40 U/g of dry substrate, A. niger ATCC 16404) was obtained in a 0.5 L rotating drum bioreactor at 40 °C filled half filled with solid biomass composed of rice byproduct (86% wt/wt), whey (12% wt/wt) and CaCl₂ (2.0% wt/wt). The best result for ethanol fermentation (11.7 g/L of ethanol) was obtained after 12 h of SFS at pH 4.5 and 35 °C. A comparative study of ethanol production by Trichoderma reesei CCT 2768 and A. niger ATCC 16404 complexes under the same optimised SFS and SSF conditions was also performed, revealing that ethanol production by the A. niger enzyme complex was 2.25 times higher than that by T. reesei. These findings suggest that the ethanol production using crude enzymatic complexes produced by A. niger and agroindustrial biomass described in this paper is very promising in terms of disposal of the whey produced by cheese-making and other dairy food processing.     

Novel core-shell-like Ni-supported hierarchical beta zeolite catalysts on bioethanol steam reforming

Hierarchical-Beta zeolites have been hydrothermally synthesized by adding a new gemini organic surfactant. The used gemini surfactant play the role of a “pore-forming agents” on the mesoscale, on the same time, providing alkaline environment for the system. With this hierarchical Beta zeolite as the core support, we successfully prepared a shell layer of Ni-containing (22 wt%) petal-like core-shell-like catalyst and applied it to bioethanol steam reforming. At the reaction temperature of 350 °C–550 °C, the conversion rate of ethanol and the selectivity of hydrogen were always above 85% and 70%. After reaction of 100 h on stream at 400 °C, there were not obvious inactivation could be observed on NiNPs/OH-MBeta catalyst.