食品中脂肪的超声提取快速测定法研究

食品中脂肪的测定一般采用国家标准检验方法,但这种方法存在操作时间长,步骤繁琐等问题.本实验采用超声波提取技术,对食品中脂肪的含量进行了提取测定.考察了超声消解时间、超声浸提时间、乙醚、乙醚一石油醚混合液等因素对测定结果的影响,用正交法确定了最佳条件.结果表明:本法处理样品时,不需要加热,缩短了样品提取时间,简化了测定步骤、大大节约了能耗,易于对大批量样品的脂肪含量的同时测定,并可借鉴于其它样品中有效成分的提取.     

植脂末中脂肪测定方法研究

<正>分别使用脂肪测定中常用的索氏提取法、酸水解法、碱水解法对植脂末中脂肪测定进行了对比研究,并且对乙醚和石油醚的提取效果进行了研究,实验结果表明索氏提取法和碱水解法不适合植脂末中脂肪的测定,酸水解法可以作为植脂末脂肪测定的推荐方法,石油醚(30℃~60℃)完全可以替代乙醚作为植脂末脂肪测定的提取溶剂。     

消除乳化现象的简易方法

食品的酸水解法是对试样加热、加酸水解破坏蛋白质及纤维组织 ,使结合脂肪游离后 ,再用乙醚提取 ,然后进行测定。在测定过程中 ,用乙醚提取时会遇到不同程度的乳化现象。为消除这一现象 ,我们在实际工作中摸索出简单易行的处理方法。按照国标检验方法 (GB 5 0 0 9 6— 1985 )中的 8 3“……并用石油醚 -乙醚等量混合液冲洗塞及筒口附着脂肪。静置 10～ 2 0min”进行操作 ,如发现乳化现象 ,可将量筒内全部溶液倒入一离心管中 ,于离心机中以 2 5 0 0r min速度离心 5min后 ,吸上清液于已恒重的锥形瓶中待测用。采用简单易行的离心法 ,可有效地…     

碱水解法测定乳及乳制品中脂肪的含量

目的建立简单、快速的碱水解法测定乳及乳制品中脂肪的含量。方法取0.5 g样品于离心管中,用10 mL纯水复溶后加入2 mL氨水(25%)水解并65℃水浴20 min。加入乙醇沉淀蛋白质并使用乙醚、石油醚提取样品中脂肪。将上清液提取至收集瓶中,蒸干提取液,称量收集瓶前后质量,计算样品中脂肪含量。结果此法测得样品脂肪含量为26.53 g/100 g,结果相对偏差为0.37%。测定值在质控样品值满意区间内,且符合国标规定的两次独立测定结果之差≤0.3 g/100 g的要求。结论本法测定乳及乳制品中脂肪的含量具有简便、快速、重现性好的优点,适合实验室日常样品测定及考核使用。     

测定粮食脂肪酸值用苯和石油醚作溶剂的比较

测定粮食中的脂肪酸值,一般都是按GB5510—85方法用苯为溶剂进行测定的。但溶剂苯易燃、易爆,挥发性大,且毒性较大,对分析工作者的身体健康影响较大。根据脂肪酸能溶解于苯、石油醚和乙醚等特性,分别用苯、石油醚作溶剂,而操作方法仍按GB5510—85不变,对小麦、玉米、稻谷样品进行测定,从测定数据结合相应理论进行综合分析,证明了石油醚取代苯作溶剂     

高效液相色谱法同时测定人乳中视黄醇、 α-生育酚和类胡萝卜素

目的 应用高压液相色谱法同时测定人乳中视黄醇、α-生育酚、叶黄素和β-胡萝卜素。方法 人乳样品经皂化后, 石油醚乙醚提取, 氮吹浓缩后, 用C30柱分离, 经紫外检测器和荧光检测器检测4种被测物。结果 4种脂溶性维生素在各自浓度范围内线性良好, 相关系数均大于0.9990;三浓度水平加标回收率在70%~120%之间, 相对标准偏差均小于20%。结论 本文将校准后的标准品用液相色谱法进行纯度鉴定,提高了检测的准确度。通过方法学验证了本方法的准确性, 灵敏性和稳定性,可同时测定人乳中视黄醇, α-生育酚, 叶黄素和β-胡萝卜素的含量。通过对100个成熟乳样品的分析, 初步建立了人乳中脂溶性维生素含量数据库。     

高效液相色谱法同时测定人乳中视黄醇、α-生育酚和类胡萝卜素

目的应用高压液相色谱法同时测定人乳中视黄醇、α-生育酚、叶黄素和β-胡萝卜素。方法人乳样品经皂化后,石油醚乙醚提取,氮吹浓缩后,用C30柱分离,经紫外检测器和荧光检测器检测4种被测物。结果 4种脂溶性维生素在各自浓度范围内线性良好,相关系数均大于0.9990;三浓度水平加标回收率在70%~120%之间,相对标准偏差均小于20%。结论本文将校准后的标准品用液相色谱法进行纯度鉴定,提高了检测的准确度。通过方法学验证了本方法的准确性,灵敏性和稳定性,可同时测定人乳中视黄醇,α-生育酚,叶黄素和β-胡萝卜素的含量。通过对100个成熟乳样品的分析,初步建立了人乳中脂溶性维生素含量数据库。     

肉制品中山梨酸、苯甲酸的气相色谱分析方法的研究

建立了肉制品中山梨酸和苯甲酸的气相色谱毛细管色谱柱检测方法。样品用石油醚-乙醚高速匀浆的方法提取后,通过改变其酸碱度而改变其在有机相和水相中分配比的方法,去除脂肪等杂质的干扰,用FFAP毛细管色谱柱FID检测器进行检测。方法的变异系数在1.2%～3.9%之间,回收率在89.0%～99.2%之间,最低检出限为1mg/kg。该方法具有步骤简单、准确度和灵敏度高的特点,非常适用于肉制品中山梨酸和苯甲酸的检测。     

气相色谱法测定香辣酱中防腐剂的含量

建立了香辣酱中山梨酸和苯甲酸的气相色谱毛细管色谱柱检测方法。样品用石油醚-乙醚高速匀浆的方法提取后,通过改变其酸碱度而改变其在有机相和水相中分配比的方法,去除脂肪等杂质的干扰,用FFAP毛细管色谱柱FID检测器进行检测。方法的回收率在89.0%~99.4%之间,变异系数在1.2%~3.9%之间,最低检出限为1mg/kg。该方法具有步骤简单、准确度和灵敏度高的特点,非常适用于香辣酱中山梨酸和苯甲酸的检测。     

脂肪测定仪测定香肠中脂肪含量的研究

采用脂肪测定仪测定香肠中脂肪的含量,结果表明,所测样品中脂肪的含量为8.2%,该方法简单、准确度高,适用于香肠中脂肪含量的测定。     

Antioxidant activity of ethanol and petroleum ether extracts from Brazilian propolis

Antioxidant activities of ethanol and petroleum ether extracts from Brazilian propolis were determined by α,α-diphenyl-β-picrylhydrazyl (DPPH) radical-scavenging and ferric thiocyanate (FTC) methods, using α-tocopherol and butylated hydroxytoluene (BHT) as references. The DPPH assay showed that ethanol extract possessed significantly higher activity compared with BHT and petroleum ether extract but lower than that of α-tocopherol. Results from the FTC assay indicated that the activity of ethanol extract was higher than that of α-tocopherol and petroleum ether extract but lower than BHT. Basically, this antioxidant activity was dose-dependent and ethanol extract exhibited higher activity than that of petroleum ether extract at the same concentration. Additionally, the chemical constituents of propolis were determined, and results showed that the propolis contained high content of antioxidant compositions, such as flavonoids (73.00 g kg⁻¹), total phenolic compounds (134.40 g kg⁻¹), and Vitamin E (0.16 g kg⁻¹), which contributed greatly to its strong antioxidant activity.     

Methods to purify and determine rubratoxins

Rubratoxin were recovered from cultures of Penicillium rubrum after the mold grew in natural substrates, a semi-synthetic medium, and a glucosemineral salts broth. Substrates that contained rubratoxins were extracted with: diethyl ether, ethyl acetate-benzene, ethanol (100%), ethanol-acetone, acetonitrile, or diethyl ether with refluxing at 45 degrees C. Extracts were screened for rubratoxins by thin-layer chromatography. Some extracts were partially purified with a column of silicic acid using acetone as the eluant. Other extracts were purified (primarily removal of pigments) using columns of silica gel plus Celite and gradient solvent elution. Most rubratoxin B (1.9 mg/g or 0.77 mg/ml) was recovered when corn, rice, or glucose-salts broth were extracted successively with diethyl ether, ethyl acetate-benzene, and diethyl ether or when samples were adjusted to pH 1.5 before refluxing with diethyl ether at 45 degrees C for 1--4h. Most rubratoxin A (0.1--0.15 mg/ml or 1.0 mg/g) was obtained from samples of corn extracted twice each with ethyl alcohol, acetone, and ethyl acetate; from glucose-mineral salts broth extracted with diethyl ether; or from yeast extract sucrose broth extracted with diethyl ether and refluxed for 4 h at 45 degrees C. Large amounts of fairly pure rubratoxin A (up to 400 mg) and rubratoxin B (greater than lg) were obtained with a combination of preparative thin-layer and column chromatography.     

河南烤烟（40级）石油醚提取物含量的研究

烟草石油醚提取物对烟叶综合质量有着重要影响，因此，研究不同等级烟叶石油醚提取物具有重要意义。本实验测定了河南烤烟（４０级）各等级烟叶石油醚提取物的含量。通过分析可知：颜色相同时以中部叶石油醚提取物含量最高，上部叶次之，下部叶最低；部位相同时烟叶颜色越深，石油醚提取物含量越高；部位相同颜色相同时烟叶等级越高，石油醚提取物含量越高，此外，石油醚提取物的含量还与烟叶成熟度、叶片结构等有关系，这对研究各等     

烤烟品种中烟特香301烤后烟叶石油醚提取物分析

为进一步明确特征香韵烤烟品种中烟特香301与中烟100香韵差异的物质基础,采用气质联用技术对二者中部烟叶的石油醚提取物进行测定,并进行了主成分分析（PCA）和偏最小二乘-判别分析（PLS-DA）。结果表明,中烟特香301和中烟100烤后烟叶石油醚提取物中各鉴定到99和98种化合物,其中共有化合物87种,中烟特香301和中烟100各自特有化合物12和11种。中烟特香301的酯类、酸类、醇类、酮类、烯类和醛类化合物的相对含量均高于中烟100,共有化合物中,二者含量差异化合物有29种,二氢猕猴桃内酯、巴伦西亚橘烯、香叶基芳樟醇、巨豆三烯酮等28种成分的含量显著高于中烟100。该结果为揭示中烟特香301香韵风格形成的物质基础提供了参考。     

小甘菊花有效成分的初步研究

采用水提取法、醇提取法和石油醚提取法对小甘菊花的化学成分进行了比较全面的定性实验。水提取物中检测出有蛋白质、氨基酸、糖类、生物碱、有机酸等物质，醇提取物中检测到了酚类、有机酸、挥发油、黄酮类和生物碱等化学物质，酸水液中检测到了生物碱，石油醚提取物主要作为挥发油、甾体、油脂、皂甙、内酯及香豆素等亲脂性成分的检测。     

Simultaneous determination of bisphenol A-diglycidyl ether, bisphenol F-diglycidyl ether and their hydrolysis and chlorohydroxy derivatives in canned foods

A new method for the simultaneous determination of bisphenol A-diglycidyl ether (BADGE), bisphenol F-diglycidyl ether (BFDGE) and their hydrolysis and chlorohydroxy derivatives in canned foods is presented. Oily and aqueous food samples were extracted with tert-butyl methyl ether and acetonitrile, respectively. The compounds in both extracts were determined by using reverse-phase gradient high-performance liquid chromatography with fluorescence detection. Optimization of extraction and chromatographic determination is outlined in detail. After validation the method was used to analyze various canned food samples, such as tuna and sardine in oil, vegetables, fruit cocktails, etc. In none of the samples were significant amounts ( >100 μg/kg) of BADGE or BFDGE found, whereas in most samples BADGE/BFDGE chlorohydroxy compounds were detected. These originate most probably from the use of organosol varnishes instead of epoxy resins. Risk assessment and regulations of these compounds by the European Union are urgently needed. Additionally, the syntheses and characterization of the not available standard compounds bisphenol A-p-glycidyl-p′-(3-chloro-2-hydroxypropyl) ether (BADGE.HCl) and bisphenol A-p-(2,3-dihydroxypropyl)-p′-(3-chloro-2-hydroxypropyl) ether (BADGE.HCl.H₂O) are presented. Received: 28 July 1999 / Revised version: 29 October 1999     

山东烤烟烟叶石油醚提取物的对比分析

为合理使用山东烟叶,对2003年山东省14个烟叶基地生产的NC89、NC82、CF965、K326和云烟85等225个烤烟初烤烟叶样品X2F、C3F和B2F的石油醚提取物总量进行了测定。结果表明:①不同部位和不同产地烟叶的石油醚提取物总量差异显著;②不同品种烟叶的石油醚提取物总量的差异不明显。结论:采用不同部位和不同产地的山东烟叶调整卷烟产品的香气量效果应比较明显,而用不同品种的烟叶调整卷烟的香气量,效果可能不明显。     

光皮树籽抽出物的成分分析

为了分析光皮树籽抽提物的化学成分,采用无水乙醇、丙酮、正己烷、石油醚和乙酸乙酯分别抽提光皮树籽,抽出物经活性炭脱色后进行GC-MS 分析。结果发现,无水乙醇和丙酮抽出物中主要含有游离的棕榈酸、油酸和亚油酸,其中亚油酸相对含量最高,达到52% 以上,油酸相对含量最低,不超过8.2%。正己烷、石油醚和乙酸乙酯抽出物中甘三酯的脂肪酸组成主要是棕榈酸、硬脂酸、油酸和亚油酸,其中油酸相对含量最高,达到42% 以上,其次是亚油酸,总不饱和脂肪酸相对含量超过70%。抽出物中未发现三不饱和脂肪酸。     

NEUTRAL DETERGENT FIBER CHANGES DUE TO HEAT DAMAGE FROM SOXHLET EXTRACTION AND DRYING1

The effects of solvent extraction and drying on neutral detergent fiber (NDF) values of foods of high sugar content were evaluated. It was found that Soxhlet extraction with a 1:l mixture of acetone and petroleum ether resulted in 117% higher NDF value for raisins than was observed for the untreated sample. This solvent mixture extracted approximately 5wo as much lipid material as did diethyl ether. The addition of sugar as glucose or sucrose and cooking at low boil for five minutes did not affect the NDF value of whole wheat flour. However, cooking caused the 1:l acetone petroleum ether extractables to be decreased. Soxhlet extraction and subsequent drying did not affect the NDF values of spinach, parsnips, cherries, or raspberries. The conservative use of heat as in Soxhlet extraction and subsequent drying did not consistently affect NDF values of the foods studied.     

Attractancy of diethyl ether extracts of Arachis hypogaea (Linnaeus) (Papilionaceae), Citrullus lanatus (Thunberg) (Cucurbitaceae) and Irvingia gabonensis var. excelsa (Baillon) (Irvingiaceae) to Oryzaephilus mercator (Fauvel) (Coleoptera: Silvanidae)

Volatiles of the diethyl ether extracts of I. gabonensis, C. lanatus and A. hypogaea attracted 1–7 and 28–42-day-old adult O. mercator when tested in a two-choice pitfall Petri dish bioassay. For both age groups, a significant difference was observed in response between fed and starved adults to the different extracts. Differences in starvation time did not affect responses of individuals in the 1–7-day-old group; a significant effect was observed in the 28–42-day-old group.

Adults, 28–42-day-old were significantly more responsive to virtually all extracts than 1–7-day-old adults. Responses of adults in each age group to the different extracts were not significantly different. The time of trial within the period 0900–1900 h did not significantly affect the response of adults in both age groups, starved for 2 days, to any extract.