Odor active compounds content in spices and their microencapsulated powders measured by SPME

Within this study, main odorants of marjoram and thyme (linalool and thymol) were determined in spices and microencapsulated powders using solid-phase microextraction (SPME). Analyses were conducted on selected batches of spices before and after decontamination and on microencapsulated powders prepared for technological purposes (improvement of aroma in decontaminated spices). Conditions of SPME analyses were determined for individual compounds and matrices. Determination of total and surface contents of compounds and the percentage dependencies between encapsulated and surface aroma made it possible to identify the best powders in terms of their quality.     

R-HPLC检测红景天苷方法研究

建立反相高效液相色谱法检测红景天苷方法。采用HypersiLC1810gm,4.6mm×300mm反相色谱柱,LC-10AT泵,SPD-l0A检测器,确定了其检测条件:检测波长278nm,进样10μL,洗脱液为乙腈∶磷酸水溶液为1∶12(磷酸调节pH3.5),流速1.0mL/min,该条件下红景天苷的出峰时间为8.891min,峰形较好,重复性好,灵敏度高,能满足红景天原料和其保健食品中红景天苷的检测要求。     

Folate concentrations of fast foods measured by trienzyme extraction method

Folate concentrations in common fast foods containing beef were measured using a new trienzyme folate extraction method and compared to the values using traditional folate conjugase. A total of 56 fast foods were purchased from local restaurants after the 1998 mandate of folic acid fortification in enriched cereal grains. One serving of hamburger, sandwich, pizza (one eighth of a 30-cm pizza) and Mexican foods contained a mean of 314 (±98, S.D.), 401 (±115), 221 (±45) and 282 (±126) μg of folate, respectively. Breakfast items provided the lowest folate amount among the foods (165±89 μg per serving). These values are markedly higher than those in the literature most likely due to the mandate of folic acid fortification in cereal-grain products and the use of the new folate extraction technique. We hope that the information presented here is a useful means to accurately calculate dietary folate intake.     

邻苯三酚自氧化法测定不同蜂产品抗氧化活性的研究

以蜂胶、蜂花粉、蜂王浆、蜂蜜为材料,利用邻苯三酚自氧化法分别测定和比较了1%蜂胶醇提液、5%蜂花粉醇提液、10%蜂王浆醇提液、10%蜂蜜醇溶液对超氧阴离子自由基(O-2)的清除效果.结果表明,4种蜂产品对超氧阴离子自由基(O-2)均有较好的清除效果,随着样品加入量的增多清除效果也越强,并呈现量效关系,但加入相同样品量时,表现为1%蜂胶醇提液和5%蜂花粉醇提液清除效果最好,10%蜂王浆醇提液、10%蜂蜜醇溶液次之.说明蜂胶、蜂花粉、蜂王浆、蜂蜜都能清除人体内过多的超氧阴离子自由基(O-2),其中蜂胶和蜂花粉清除效果最好,是很好的抗氧化食品.     

中段切断称量法测棉纤维细度之误差浅析

棉纤维细度是影响棉纱线性质的重要因素。中段切断称量法测试棉纤维细度的方法普遍存在测得数值偏大的现象。文章对中段切断称量法进行了分析研究,归纳出因人为因素和客观因素造成细度结果偏大,建议采用数值修正和多种测试方法进行交叉校验,同时,要提高操作人员的技术水平,保证测试结果的准确、可信。     

Dietary fibre fractions in cereal foods measured by a new integrated AOAC method

The reliable determination of soluble, insoluble and total dietary fibre in baked goods and cereal flours is an important issue for research, nutritional labelling and marketing. We compared total dietary fibre (TDF) contents of selected cereal based foods determined by AOAC Method 991.43 and the new AOAC Method 2009.01. Fifteen bread and bakery products were included in the study. Our results showed that TDF values of cereal products determined by AOAC Method 2009.01 were always significantly higher than those determined by AOAC Method 991.43. This was explained by the inclusion of low molecular weight soluble fibre fractions and resistant starch fractions in the TDF measurement by AOAC 2009.01. This documents that nutritional labelling of cereal products poses the challenge how to update TDF data in nutrient databases in a reasonable time with an acceptable expenditure.     

GC-O-MS对白酒中的糠味物质的研究

以萃取率为评价指标,采用单因素实验对SPME萃取白酒中香气化合物的萃取条件进行了优化,最佳条件为:顶空模式,萃取温度60℃,萃取时间40min,加盐量2.5g,搅拌转速500rpm,解析时间6min,通过GC-O分析,确定了2-糠酸乙酯、4-乙烯基苯酚、4-乙烯基愈创木酚、1,4二甲氧基苯、1,2二甲氧基苯、笏、土嗅素、[3.3.1]壬二烯-3,7-二酮等八种物质是白酒中的糠味物质;建立了外标法快速定量七种主要的糠味物质的方法,该方法检测范围内线性关系良好(R2>0.99),并且有较好的重复性和回收率;通过对白酒酿造原辅料稻壳,高粱,高粱壳及大曲中糠味物质的调查,初步确认了典型的糠味物质产生的来源,生糠味物质[3.3.1]壬二烯-3,7-二酮主要是在稻壳受热时产生的,土糠味的土嗅素和湿糠味的1,2二甲氧基苯主要来自于大曲,是由微生物的污染产生的,2-糠酸乙酯是发酵过程产生的,呈现咸糠味。     

马铃薯淀粉包埋脱除大蒜臭味

为了保护大蒜的活性成分和掩盖大蒜的不愉快气味,本研究采用研磨法利用马铃薯淀粉的螺旋结构对大蒜 的有机硫化合物进行包埋,以马铃薯淀粉、大蒜（干基）为原料,用包埋率和脱臭效果为指标优化其脱臭工艺,并 对样品进行结构表征。通过高效液相色谱法测定得到的最佳脱臭条件为：马铃薯淀粉与大蒜（干基）质量比3∶1, 研磨时间2.5 h,在此条件下,所得产品的包埋率为（90.63±1.11）%,感官鉴评得分95 分。通过扫描电子显微镜观 察可知,淀粉颗粒被破坏,呈现团聚结构;X射线衍射仪分析表明淀粉的结晶度降低,傅里叶变换红外光谱和热重 分析结果表明样品具有良好的稳定性;通过气相色谱-质谱联用分析可知,大蒜中11 种有机硫化合物的成分在样品 中被全部检出,说明研磨法能促进马铃薯淀粉包埋新鲜大蒜中的臭味物质,既保留大蒜中有机硫化合物又可以达到 脱臭的目的。     

Effect of slaughter method on the progress of rigor of rainbow trout (Salmo gairdneri) as measured by an image processing system

Rainbow trout ( Salmo gairdneri ) were slaughtered by AC and DC electrocution, exposure to elevated concentrations of carbon dioxide and by a blow to the head. The fish were subsequently bled and placed in ice.
At regular intervals after slaughter the fish were taken from the ice and placed on a horizontal table with the posterior half of the fish overhanging the edge. The angle which the fish's tail formed with the vertical was used as an index of rigor and was measured by an image processing system. It was found that the stages of rigor were statistically the same for the four different treatments except that the onset of rigor for fish given a blow on the head was delayed.     

Thermal diffusivity of kiwifruit skin,flesh and core measured by a modified Fitch method

Abstract

This paper reports the results of thermal diffusivity of kiwifruit measured using the modified Fitch method. The three unique structural components of the fruit, i.e. skin, flesh and core, were used in the measurement. The thermal diffusivities of skin, flesh and core are 0.78±0.08 x 10^‐7, 1.14±0.06 x 10^‐7 and 0.95±0.02 x 10^‐7 (m²s^‐1) respectively.     

Water retention of treated stratum corneum measured by a coupling method: thermal desorption-mass spectrometry

A thermal desorption autosampler coupled to a mass spectrometer has been used to measure the in vitro water retention of human stratum corneum as a function of treatment applied. Samples were treated with ingredients possessing good hygroscopic properties which are used in the formulation of moisturizing creams. After being treated, stratum corneum samples were dried and rehydrated and then analysed. The paper describes the method used to quantify their hygroscopic capacity in terms of the percentage of water retained. Ten humectants were examined, of which urea, glycerine, ammonium lactate and a new salt of an α-hydroxy acid were found to have the highest activities. This method can also be used to quantify the water retention capacity of various types of pathological skin such as ichthyosis and psoriasis.     

固相微萃取-GC-MS定量检测白酒中两种异嗅物质

建立利用固相微萃取技术结合气相色谱-质谱联用法测定白酒中两种异嗅物质--二甲基二硫和二甲基三硫的方法,并对前处理的条件进行优化。结果表明,最佳前处理条件为：100 μm PDMS萃取头、萃取温度50 ℃、萃取时间20 min、NaCl添加量1.5 g、解吸时间5 min;该方法简便、快速,对于二甲基二硫（R2=0.999 1）和二甲基三硫（R2=0.999 5）具有良好的线性,其检出限分别为0.04 μg/L和0.06 μg/L,相对标准偏差均不高于3.98%,加标回收率在93.17%～112.07%之间。该方法适用于白酒中二甲基二硫和二甲基三硫两种异嗅物质的定量分析。     

Determination of lactose by an enzymatic method

The general methodology used for the determination of lactose in milk is considered, namely, polarimetry, gravimetry, infrared, colorimetry, gas-liquid chromatography, and high pressure liquid chromatography. The criteria for selecting an ideal analytical method followed by the relevance of most of these criteria in enzymatic methodology are discussed. The principle of the Boehringer-Mannheim method is presented, i.e., lactose is hydrolyzed to glucose and beta-galactose in the presence of beta-galactosidase and water. beta-Galactose is then oxidized by nicotinamide-adenine dinucleotide to galactonic acid in the presence of beta-galactose dehydrogenase. The amount of reduced nicotinamide-adenine dinucleotide formed is stoichiometric with the amount of lactose and is measured at 340 nm in a spectrophotometer possessing a slit width of less than or equal to 10 nm. The results of a recent Association of Official Analytical Chemists collaborative study of the B-M method are presented. From the overall mean of results on all samples, determinations by the enzymatic method averaged .49% lower than by the Association of Official Analytical Chemists gravimetric method. Standard deviations were similar for three sets of blind duplicates, which ranged between 3.67 and 4.55% lactose. F-Values revealed that variations between means obtained by laboratories differed significantly as compared with variations within laboratory means. The method has received Official First Action recognition by Association of Official Analytical Chemists.     

真空处理对刨花板气味改善的初步研究

以厚度为18 mm的刨花板和双面饰面刨花板为研究对象,分析不同真空处理条件对板件气味改善的作用.研究结果表明,在本试验条件下,按"常温-真空度10 mbar-循环40次"参数进行抽真空处理,对双面饰面刨花板的气味有较好的改善效果,对刨花板素板则无显著效果,其原因和影响规律还有待进一步研究.     

臭氧氧化、涂膜及其结合法清除榴莲果肉表面臭味

采用臭氧氧化、可食膜掩蔽、臭氧氧化＋可食膜掩蔽3 种方法,清除榴莲果肉表面臭味,并利用电子鼻定量检测除臭效果。将密封榴莲果肉样品的系统开0、8、16 个小孔,减小榴莲果肉的裸露面积,使榴莲臭味形成3 种质量浓度梯度,电子鼻信号曲线能较快地达到平稳状态,用于建立偏最小二乘（partial least squares,PLS）法分析模型。主成分分析表明,3 种不同孔数处理后样品的响应值有明显差异;PLS法建立的榴莲果肉臭味气体相对含量模型表明,以榴莲果肉臭味气体相对含量建立的PLS法分析线性拟合曲线的相关系数为0.997,16 孔样品的榴莲果肉臭味气体相对含量的平均相对误差小于10%,即电子鼻可以准确地测定榴莲果肉臭味气体的相对含量;硬脂酸膜（膜液质量浓度为硬脂酸2.70 g/L＋甘油45.00 g/L＋大豆分离蛋白90.00 g/L）掩蔽榴莲臭味的效果最佳;臭氧氧化＋可食膜掩蔽方法清除榴莲果肉表面臭味的效果最好。     

辣椒红色素的提取与利用大孔径树脂脱除辣素的研究

研究了在辣椒红色素的提取过程中,大孔径树脂对辣椒碱的吸附脱除方法,探讨了影响色素品质和脱辣效果的工艺条件。AB-8树脂对辣椒碱具有良好的吸附,在4.0mL/min的流速和25℃的温度下可有效脱除色素产品中的辣椒碱,色素产品的收率2.71%,色价121(E11c%m260nm)。     

A rapid non‐destructive method for fish quality control by determination of smell intensity

The ‘Cosmos’ instrument (Japan) was applied to the evaluation of fish quality in six species of different origins, by determination of smell intensity. Pond‐raised fish (trout, carp, silver perch, tilapia, barramundi) were stored in ice for 4–5 weeks and frozen/thawed mackerel was kept at room temperature for 74 h. The fish quality was examined by organoleptic assessment, by determination of smell intensity and by tests of the chemical (total volatile basic nitrogen, hypoxanthine and histamine) and dielectric (Torrymeter) properties. Strong correlation was found between the organoleptic and ‘Cosmos’ results, whereas the data from the chemical and Torrymeter analyses were relatively poorly correlated with the sensory evaluation and ‘Cosmos’ data. Thus the application of the ‘Cosmos’ instrument for objective quantitative evaluation of fresh and chilled fish quality by determination of smell intensity seems practicable. The ‘Cosmos’ instrument is hand‐held and portable as well as being rapid and non‐destructive in operation; therefore it could be used for evaluation of fresh and chilled fish in the field and on board fishing vessels. Copyright © 2003 Society of Chemical Industry