浅谈复合软包装材料的异味问题

复合软包装材料产生异味是一个重大质量事故．尤其是食品类包装材料．对异味要求尤其严格．一些味道不浓的食品．如奶粉、奶酪、饼干、曲奇、玉米片等．一些脱脂和低脂制品对异味更敏感。虽然高分子材料本身无任何异味．但是在一系列的成型加工过程中．所添加的各种改性剂、各种附加材料及高分子材料本身热降解都可产生异味。因此．包装材料产生的异味种类繁     

厨房妙招

柠檬让你的厨房远离异味都说柠檬是女人的水果。一个柠檬能令女人从头美丽到脚——美白、减肥、消斑、美齿、美体、美发、去皱……除此之外,柠檬还可以帮你消除厨房的异味哦!1跟厨房腥、膻异味说拜拜在洗碗水中放几片柠檬皮(还可再加点橘子皮,或滴几滴醋),就能消除碗碟餐具上的腥、膻等异味。同时,它还能使硬水软化,增加瓷器的光泽。而切过鱼的菜刀,用柠檬皮擦一擦就能去腥;锅里的腥味,放点柠檬皮用水煮一会儿就可完全消失。如果手上占有腥味,就用柠檬皮搓手,如果能在柠檬水里泡泡,效果更佳。而且,用柠檬皮擦手,其所含的柠檬油可使皮肤细腻光滑。     

烹调四大祛腥妙招

动物性食品一般都存在腥味物质，尤其是水产品的气味突出。他随着食物新鲜度的降低而增强，这些异味物质不仅使人反胃，而且食用后会对人体健康有害。烹调时祛腥方法很多，可根据原料的异味程度，综合采用一些措施，以达到祛腥臭味之目的。     

红心萝卜汁和萝卜红色素中异味物质的气相色谱分析

本文初步探讨了红心萝卜汁和萝卜红色素中异味物质的气相色谱分析方法。此方法可用于分析异味物质的化学组成和结构、了解Glucoraphenin在各种条件下的降解途径和产物,以及探讨防止Glucoraphenin降解和除去其降解产物的研究。     

罗非鱼酶解液酵母发酵脱腥工艺及其挥发性成分的研究

罗非鱼酶解液营养价值丰富,但具有一定的腥异味,该研究旨在通过酵母发酵脱腥工艺来改善风味,从而提升罗非鱼的附加值.以腥味值和DPPH自由基清除率为评价指标,通过正交试验对发酵脱腥工艺进行优化,得到最佳条件为:酵母添加量7 g/L,发醇时间1.5 h、发酵温度30℃.采用气相色谱-质谱联用(gas chromatograp...     

肉类食品中典型异味物质研究进展

采用文献调查法论述了水产及畜禽肉类中典型异味物质的种类、分布、来源、影响因素及消除方法等。相关研究发现,肉类中典型异味物质主要有土臭素、二甲基异莰醇、己醛、粪臭素、雄甾烯酮、4-甲基辛酸、4-甲基壬酸等。其中,土臭素、二甲基异莰醇主要存在于鱼皮和内脏组织中,是水体中鱼腥藻和颤藻等的代谢废物,通过循环水养殖法和酸碱法等可去除;己醛主要分布在多种肉类脂质丰富的部位,多因脂质氧化产生,因此采用抗氧化剂能有效降低其含量;粪臭素、雄甾烯酮主要分布在猪脂肪及其肌肉组织中,分别来源于L-色氨酸的降解和睾丸组织的分泌,通过调节饲料成分和免疫去势等方法可降低其含量;4-甲基辛酸与4-甲基壬酸主要分布在羊肉皮下脂肪中,多因脂肪降解产生,漂洗、预煮脱腥、复合脱腥、微生物脱腥等是其主要去除方法。生产中可以通过选育动物品种、调整动物饲料成分、改善动物生活环境和肉类贮存条件等方法有效减少或控制畜禽肉类中典型异味物质的产生。     

焯、汆、泹、过四技法

焯、汆、泹、过,是在烹调菜肴前对一部分原料进行初步热处理的几种技法。这几种技法能部分除去原料当中的腥、膻、臊等异味,使菜肴色泽鲜艳、口感脆嫩、味道鲜美。虽然焯、汆、泹、过都是原料的初步热处理方法,但在具体操作时,工艺上有较大的差异,具体方法如下。     

Co-salen型仿酶体系降解β-O-4型木素模型化合物的研究

为了研究Co—salen型仿酶体系对木素的降解机理,采用由Co—salen、吡啶、H2O2、O2组成的Co—salen型仿酶体系对β-O-4型木素模型化合物——愈创木基丙三醇-β-愈创木基醚进行仿酶降解的研究,并采用GC—MS等方法分析了该β-O-4型木素模型化合物在降解过程中的结构变化,在此基础上对这种仿酶体系降解的机理进行了初步探讨。研究表明：Co—salen型仿酶体系对β-O-4型木素模型化合物有较强的降解能力,降解后产生一系列含羟基、醛基和羧基的芳香族低分子化合物,根据反应产物的结构可以说明β型木素模型化合物的主要降解途径为：β醚键断裂、Ca—cp键断裂、烷基-芳基键的断裂和苯环开环反应等。本研究为该仿酶降解体系在无污染漂白工业上的应用提供理论依据。     

蔬菜残留农药降解新方法的研究

农药残留是影响我国食物安全的一大关键问题。文中建立了蔬菜农药降解效果分析体系,自主研发了高浓度臭氧密闭动态增压降解方法,分析了该方法对蔬菜中常见的敌敌畏、甲胺磷和呋喃丹等3种农药残留的降解效果。结果表明,该降解方法在进行多农药高浓度残留降解时其降解效果显著,有机磷降解率均超过93%,呋喃丹降解率超过88%。     

应用交叉-转动过滤器的超滤和毫微过滤净化水

美国造纸科学和技术研究院科技人员研究了制浆和造纸废水中溶解木素的光降解效果。在间歇系统中试验了用二氧化钛（TiO2）光催化降解木素反应，所有试验采用单因子设计方法，在没有催化剂情况下，光降解2h后，废水中溶解木素去除率仅4．6％；而TiO2用量10mg／L，光催化降解2h后，明显降低了最终木素浓度，木素去除率达82％。为了确定最佳操作条件，试验了催化剂TiO2用量和光照强度对去除废水中木素的影响，当TiO2最佳用量为10mg／L和光照强度较大时，对废水中总的木素降解效果较好。TiO2催化剂的物理化学性质很稳定。可回收循环利用。     

Methodology for Quantification of Geosmin and Levels in Rangia Clam (Rangia cuneata)

The concentration of geosmin was determined in freshly dredged and 2-wk relayed rangia clam (Rangia cuneata) samples in different seasons of the year. Vacuum distillation/solvent extraction using an internal standard was followed by multiple-level standard addition gas chromatography/selective ion monitoring mass spectrometry. Most coefficients of variation were lower than 10%. On a dry-weight basis, the geosmin level in dredged clams was highest (343 ng/g) in August and averaged 51.6 ng/g in other months. A 52% reduction of geosmin was found after two week relaying during the period of May-June. However, only 1% reduction of geosmin was observed during February-March.     

Determination of temperature-dependent Henry's law constants of odorous contaminants and their application to human perception

A new method was developed to measure Henry's law constants at varying temperatures and from these data determine enthalpies of reactions for volatilization of aqueous compounds. The method was applied to 2-methylisoborneol (2-MIB), geosmin, and trans-2,cis-6-nonadienal, which are three of the major odorous compounds found in natural and drinking water. The method used static headspace equilibrium in standard odor analysis flasks and SPME-GC/MS. Dimensionless Henry's law constants were determined at 20, 25, 32, and 39 degrees C in distilled water. Their values ranged from 0.002 to 0.02 and increased with increasing temperature. The study was continued by determining the effects of different concentrations of fulvic acid added to the aqueous media. Decreases of 5-40% in Henry's law constants were observed when fulvic acid was present; however the decrease was not correlated with the fulvic acid concentration. Fulvic acid at any concentration caused a small decrease in constants for geosmin and 2-MIB, yet a more substantial decrease was obtained for nonadienal. Finally, the gas-phase concentrations were predicted using measured Henry's law constants for known aqueous concentrations of 2-MIB, geosmin, and nonadienal at 25 and 45 degrees C. An increase in the gas-phase concentration was not correlated to an increase in human perception as determined by a trained human panel. It is concluded that, after some point, panelists were not able to perceive an increase in the odorant concentration. This has important implications for controlling nuisance odors in the environment.     

(−)Geosmin sorption by enological yeasts in model wine and FTIR spectroscopy characterization of the sorbent

For the first time, we report that enological yeasts or yeast cell walls can sorb (−)geosmin, an undesirable molecule that causes critical organoleptic defects in wine at low concentrations (around 50 ng l⁻¹). The wine is described as “earthy” or “mouldy”. The influence of various post-harvesting processes on yeast (−)geosmin sorption capacity was studied. The dried yeast biomass obtained by the different processes was analysed by FTIR spectroscopy in ATR mode: structural differences were detected between the samples depending on the strain and the treatment used. Surface proteins and mainly phospholipids from the plasma membrane appeared to induce significantly different signals which may explain the different sorption capacities. The possible involvement of phospholipids in (−)geosmin sorption by yeasts highlights the complexity of this phenomenon.     

Identification of Geosmin as the Major Muddy Off-flavor of Louisiana Brackish Water Clam (Rangia cuneata)

The major compound responsible for the objectionable muddy or musty/earthy off-flavor in Louisiana brackish water clams (Rangia cuneata)was positively identified as geosmin (trans-1,10-dimethyl-trans-g-de-calol), based on gas chromatographic retention times, electron ionization mass spectra, and odor characteristics. Confirmation was based on analysis of authentic geosmin under experimental conditions comparable to those of the clam samples.     

可见光催化纸光催化剂的载覆方式及其效果研究

本课题首先制备SrTiO_3光催化剂,然后将SrTiO_3采用以下三种方式载覆于纸张中制备光催化纸:⑴直接加填抄造法制备光催化纸;⑵配制成涂料后,采用涂布法制备光催化纸;⑶将光催化剂与纸浆纤维复合制备光催化复合纤维,再与纸浆纤维混合配抄光催化纸。检测和分析光催化剂在纸张中的留着效果及光催化纸对甲醛的降解效果,比较得出最优的光催化剂载覆方式。结果表明:直接加填纸的留着率为64%,对甲醛的降解率为63.5%;涂布纸的留着率为96%,对甲醛的降解率为70.5%;光催化复合纤维纸的留着率为93%,对甲醛的降解率为73.4%。由此可见,光催化复合纤维配抄法为最佳的光催化剂载覆方式。     

自动SPME-GCMS法分析生活饮用水中臭味物质土臭素和2-甲基异莰醇

如果饮用水中的土臭素与2-甲基异莰醇的含量超标,往往会造成致嗅现象。因此,供水企业对这类嗅味物质的有效去除一直十分关注。在实践中,通过传统方法很难实现有效去除,且对这类嗅味物质的检测与分析也存在诸多不足。本文应用自动SPME技术连接thermo scientifi cTM ISQ 7000 GCMS,实现了对2-甲基异莰醇和土臭素的高效率、高灵敏度的检测,其最低检出质量浓度分别为1.0 ng/L和0.49 ng/L,满足饮用水中土臭素和2-甲基异莰醇的检测要求。     

Some critical structure factors of titanium oxide nanotube array in its photocatalytic activity

A highly ordered TiO2 nanotube array on Ti substrate was fabricated by using an electrochemical anodic oxidation method. The morphology, crystalline phase, and photoelectrochemical property of the nanotube array were characterized. The photocatalytic activity of the nanotube array was evaluated by the decolorization of methyl orange in aqueous solution using the different light sources. The effects of structure and morphology of the nanotube array on its photocatalytic activity were investigated. It was found that the photoabsorption behavior of the TiO2 nanotube film depended on the structures of the nanotube array. The nanotube array films exhibited a drastically enhanced photocurrent, and a higher photocatalytic activity compared with the TiO2 nanoparticle film prepared by the regular sol-gel method. The experimental results indicated that the film thickness markedly influenced the photocatalytic activity of nanotube array film, and the 2.5 microm-thick TiO2 nanotube array film appeared a maximum photodegradation efficiency to methyl orange. However, for a given nanotube length, the tube diameter was only very slightly affected the photocatalytic efficiency in this work. The explanation for some critical structure factors of TiO2 nanotube array in the photocatalytic activity was discussed as well.     

Effects of the origins of Botrytis cinerea on earthy aromas from grape broth media further inoculated with Penicillium expansum

Earthy “off” aromas from wine and grape juice are highly detrimental to the production of quality grape products. These volatile compounds are produced on grapes by Botrytis cinerea, Penicillium expansum and/or a combination of P. expansum and B. cinerea strains. B. cinerea strains were isolated from different (a) vineyards in Spain and Portugal, (b) grape varieties (c) bunches (i.e., sound and botrytized) and (d) positions in the botrytized bunch (i.e., interior or exterior). A novel Headspace-Phase Microextraction (SPME) followed by Gas Chromatrography/Mass Spectrometry (GC-MS) dedicated to analyze geosmin, methylisoborneol (MIB), 1-octen-3-ol, fenchone and fenchol in grape broth medium was used. Approximately 50% of the B. cinerea strains induced detectable geosmin. One strain accumulated significant amounts of anisoles, demonstrating that this contamination might already occur in the vineyard. Strains from the interior of Cainho grape bunches induced more geosmin and hence it may be possible to reduce this volatile in wine by avoiding using these grapes in case of B. cinerea attack.     

二氧化钛纳米管光催化降解苹果汁中展青霉素的工艺优化

为评价二氧化钛纳米管对苹果汁中展青霉素的光催化降解性能,本文进行了光催化降解展青霉素的工艺研究,首先利用水热法制备出二氧化钛纳米管,以其光催化降解展青霉素所用时间作为活性评价指标,考察了紫外灯功率、反应温度、pH及二氧化钛纳米管的投加量对展青霉素降解效果的影响;然后据此设计正交试验进行二氧化钛纳米管光催化降解展青霉素的工艺优化。结果表明:二氧化钛纳米管与二氧化钛光催化降解模拟汁中展青霉素的活性对比结果显示,二氧化钛纳米管比二氧化钛表现出更高的光催化降解展青霉素的活性;二氧化钛纳米管光催化降解展青霉素的最佳工艺为:二氧化钛纳米管的投加量为500 mg/L,紫外灯功率为21 W,反应温度为25℃;在最佳工艺条件下,当反应体系中展青霉素的初始浓度为1000 μg/L时,二氧化钛纳米管光催化降解模拟汁与苹果汁中展青霉素的活性对比结果显示,25 min内可将模拟汁中的展青霉素含量降低到检测限以下,45 min内可将苹果汁中的展青霉素含量降低到检测限以下。     

Odour-active and off-odour components in rainbow trout (Oncorhynchus mykiss) extracts obtained by microwave assisted distillation–solvent extraction

The odour-active and off-odour components of rainbow trout (Oncorhynchus mykiss) were evaluated by gas chromatography coupled with olfactometry and mass spectrometry. A microwave assisted distillation followed by solvent extraction (MAD-SE) method for isolation of volatiles in rainbow trout has been developed. Sensory analysis shows that the aromatic extract obtained by this method was representative of rainbow trout odour. A total of 34 and 32 odorous components were separated in DB-5 and DB-Wax column, respectively, and 29 and 27 of these compounds were identified. Among them, nonanal (green, floral), (E,E)-2,4-octadienal (green, cucumber), 2-methylisoborneol (musty), and geosmin (earthy) were the most important contributors to the aroma because they were perceived by all eight panellists in aromatic extracts by Gas chromatography–olfactometry.