豆芽中甲醛的酚试剂测定法两种前处理方法比较

目的通过对酚试剂法测定豆芽中甲醛的两种前处理方法进行比较,探讨测定豆芽中甲醛的方法。方法分别以直接浸泡法和水蒸气蒸馏法作为前处理方法,利用甲醛与酚试剂反应,在波长645 nm处测量吸光度,进行定量分析。结果直接浸泡法和水蒸气蒸馏法作为前处理方法测定的标准偏差分别为1.6%~2.3%和1.7%~2.6%,浸泡提取法重现性更好;回收率范围分别为80.1%~92.4%和80.4%~97.4%,水蒸汽蒸馏法回收率结果略高。结论在固定检测方法的条件下,可根据实验室所具备的仪器条件,选择合适的前处理方法进行样品检测。     

乙酰丙酮法测定食品中甲醛及前处理方法探讨

[目的]研究不同食品前处理方法对甲醛提取和测定的影响,为选择合适的方法提供实验依据。[方法]对5类食品分别采用4种不同的前处理方法,用乙酰丙酮分光光度比色法测定,并比较方法间差异和各自的特点。[结果]不同的前处理方法所得结果差异显著,平均回收率和相对标准偏差分别为：室温浸泡法91.7%和1.28%;加热浸泡法90.4%和1.29%;直接蒸馏法83.9%和1.27%;水蒸汽蒸馏法82.8%和1.78%。[结论]测定食品中的甲醛时,对不同食品应采用不同的前处理方法。     

盐酸副玫瑰苯胺法直接测定食品中甲醛次硫酸氢钠的方法研究

目的:建立一种特异性高、准确可靠的直接测定甲醛次硫酸氢钠(吊白块)的方法。方法:将含吊白块的样品在酸性条件下水蒸汽蒸馏,向样品蒸馏液中加入氢氧化钠,使游离出二氧化硫和甲醛,与盐酸副玫瑰苯胺反应生成一种紫红色物质,于560 nm处用分光光度计测定其吸光值。结果:在0.02 mg~0.7 mg含量范围内,其响应值与吊白块含量呈强相关性,相关系数r=0.9996,检出限为0.005 mg,相对标准偏差为3.1%,回收率93.5%~99.7%。结论:本测定方法可直接测定食品中的吊白块,准确可靠,操作简便。     

测定食品中甲醛的样品前处理方法比较

目的对测定食品中甲醛的四种样品处理方法进行比较,并对超声提取法的提取时间进行优化试验。方法用乙酰丙酮分光光度法。结果乙酰丙酮分光光度法简便,适应于大批量样品的测定。样品的前处理方法：直接蒸馏法和水蒸气蒸馏法的测定值差异无统计学意义,其中以水蒸气蒸馏法为最佳;而超声提取法和水浸泡法的测定结果则偏低,但更简单、快速,而且测定的只是游离甲醛,这对于在食品中添加甲醛或用甲醛水溶液浸泡食品,是很实用的。由超声时间实验,认为超声提取8min～10min为宜。结论实验发现,测定不同类别食品中的甲醛,样品处理应选用不同的方法,才能获德样品中的真实含量。     

吊白块的快速测定方法

食品卫生法明确规定甲醛或含甲醛的化合物禁止作为食品添加剂使用[1] 。但有些不法商贩在面粉、腐竹、粉丝等食品中加入吊白块以达到增白或增加韧性的作用 ,严重损害了消费者的健康利益。为此 ,卫生部下发了卫发电 [2 0 0 1]15号《卫生部关于严厉查处粮食制品中违法使用甲醛、吊白块等非食用原料的紧急通知》 ,并推荐了检验方法。吊白块的提取法基本为水蒸汽蒸馏法[1 2 ] ,这种方法操作繁琐费时 ,每份样品仅蒸馏就需近 1ｈ ,在对市场腐竹及粮食制品样品进行大批量监测时满足不了快速检测的需要。本文建立了一种在超声波中用水溶液提取样品的…     

食品中甲醛的乙酰丙酮-透析测定法

甲醛溶液是一种医用防腐剂,一些食品加工或销售者为提高食品的感官性能,在腐竹、粉丝、米线和水发食品中非法添加甲醛及其化合物———吊白块。吊白块的化学名称为甲醛次硫酸氢钠,当它进入人体后,分解成甲醛及亚硫酸钠,可造成肝肾等多器官损害,严重威胁广大消费者的身体健康。目前,有许多方法可以测定食品中甲醛,如盐酸苯肼法、变色酸法以及乙酰丙酮法[1-3]。在样品前处理时都需要特制的蒸馏装置,而我们采用半透膜保温法进行样品前处理,用乙酰丙酮法对甲醛进行测定,结果如下。1材料与方法1·1仪器与试剂①粉碎机;②723分光光度计;③电动恒温…     

现场快速检测食品中甲醛方法的研究

近年来,许多不法商贩在一些食品生产加工过程中加入甲醛或甲醛·次硫酸氢钠(吊白块),以增加产量或改善外观、口感等。甲醛对人体有害,世界卫生组织和欧共体都将之列为致癌物[1,2]。因此,现场快速检测甲醛是保障食品安全的重要手段。卫生部建议的检测甲醛方法为蒸馏-乙酰丙酮法。此法灵敏度虽高,但需蒸馏,不适应现场快速检测,并且在酸性条件下蒸馏有时会产生“分析本底”形成假阳性[3];而吊白块分解产生的SO2在微酸性条件下与甲醛结合会使测定值偏低[4]。本实验通过改进,建立起一种现场快速准确的检测食品中甲醛含量的方法。该法具有较强的…     

食品中甲醛合次硫酸氢钠测定方法探讨

甲醛合次硫酸氢钠,俗称吊白块.又名雕白粉、易溶于水,温度稍高或遇酸、碱即可分解为甲醛、二氧化硫,是一种禁用于食品的工业漂白剂,在食品中不得检出.但有不少面食经营户利用吊白块能够漂白增鲜而用来制作“精粉”馒头,使市售馒头异常洁白,如果食用,对人体可造成一定的危害.目前国内尚无测定食品中吊白块的标准方法,我们采用水蒸汽蒸馏,吊白块分解为甲醛与二氧化硫,甲醛馏出,与变色酸在酸性溶液中呈紫色.依据颜色深浅,比色定量.此法灵敏度高,结果准确可靠.     

两种前处理对乙酰丙酮法测定食品中甲醛的影响比较

本文对乙酰丙酮法测定食品中甲醛的两种前处理方法进行了比较，结果表明用蒸馏法进行样品前处理时。在蒸馏过程中不同食品的某些化学成分发生改变，产生甲醛而对测定结果有干扰，而采用浸泡提取测定食品中甲醛，有效避免了假阳性的发生，为方法的进一步完善提供一定的检测依据。     

豆腐中吊白块含量的测定

目的建立高效液相色谱检测豆腐中吊白块方法。方法采用超声波法对豆腐样品进行前处理,使用高效液相色谱仪参照国标《小麦粉与大米粉及其制品中甲醛次硫酸氢钠含量的测定》进行方法的建立。结果该方法的最低检出限为0.04μg/g,相对标准偏差为0.51%~3.96%,8份豆腐、1份盐卤样品均未检出吊白块,3份对照样品检出吊白块。结论高效液相色谱仪可用于豆腐中吊白块含量的测定,具有精密度高、重现性好的特点。     

萝岗区市售食品中添加剂使用情况调查

目的了解广州市萝岗区市售食品中添加剂使用情况,为政府加强食品添加剂的管理提供科学依据。方法在萝岗区相对固定监测点抽检8类食品,开展12种添加剂和3种非食用物质检测。结果共抽检328份样品获得1 420个有效数据,合格267份,合格率为81.4%。主要问题是市售米面制品和非发酵性豆制品违法添加非食用物质甲醛次硫酸氢钠,蜜饯类食品甜蜜素超标率达46.2%。结论萝岗区市售食品中甜蜜素和甲醛次硫酸氢钠超标现象比较严重,建议相关部门加强监督和检测能力,确保食用安全。     

Alkylresorcinols in wheat and rye flour and bread

The alkylresorcinol (AR) content and relative homologue composition were determined in Norwegian flours and bread. The following average values for total AR content (μg/g dm) were found: wholegrain wheat flour available only to bakers (490) and to both consumers and bakers (710), refined wheat flour (36), wheat bran (3625), wholegrain spelt wheat flour (650), refined spelt wheat flour (80), wholegrain rye flour (972), refined rye flour (90) and rye bran (2753). The C17:0/C21:0 ratio was 0.1 for wheat and 0.8–0.9 for rye, confirming that it can be used to distinguish between wheat and rye. The AR content of Norwegian refined wheat flour was higher than that of Swedish, due to a consistently higher milling extraction rate in Norway. The content of AR varied from 27 to 2766 μg/g dm in hard bread and 21 to 548 μg/g dm in soft bread. The highest contents were found in bread with a high proportion of wholegrain flour and/or bran, in agreement with earlier studies. There was a good correlation (r = 0.91) and a high compliance between calculated and analysed AR levels in soft bread, confirming that AR can be used as a biomarker for wholegrain wheat and/or rye content in a cereal product.     

Quality Assessment of Doughnut Prepared from Wheat Flour Enriched with Bambara Nut Flour

The proximate composition, pasting, and functional properties of flour blends from wheat and bambara nut at 10%, 20%, and 30% were carried out. The codes used were: DEL (90% wheat flour and 10% bambara nut flour), PIE (80% wheat flour and 20% bambara nut flour), ROW (70% wheat flour and 30% bambara nut flour), and ALE (100% wheat flour as control). Doughnuts were prepared using these blends and their sensory properties assessed. Results obtained revealed that the protein content of the flour increased with increase in bambara nut addition from 10.88–11.78%. Significant differences (p < 0.05) were observed in the fat, ash, and crude fiber (1.88–2.23%, 1.22–1.88%, and 3.96–4.02%) respectively. Doughnuts with 10% bambara nut flour (DEL) were most acceptable amongst the samples because there was no significant difference (p < 0.05) between this sample and the control in most parameters assessed.     

面制品中铝含量测定预处理方法比较研究

目的:找出面制食品中铝含量测定较优的样品消化方法。方法:采用铬天青S分光光度法测定油条、面包、馒头、膨化食品四种面制品中铝含量,对前处理的灰化法、湿法消化、高压消解、微波消解四种方法进行比较研究,对四种消化方法铝含量结果的加标回收率进行比较分析。结果:灰化法是比较好的消解方法,四种面制品中铝含量测定的精密度达到2.15%～3.21%,回收率85.3%～102.3%。结论:对于含油量较低的面制品,四种消化方法均可作为面制食品中铝含量测定的消化方法应用,但对于含油量较高的面食品不宜采用湿法消化、高压消解、微波消解预处理方法。     

中国常见植物食物中植物甾醇的含量和居民摄入量初估

目的对我国植物食物中植物甾醇的含量和分布进行分析,并初步估计了中国居民膳食植物甾醇摄入量。方法选择了常见7大类约160余种植物食物样品,用气相色谱法分析了β-谷甾醇、菜油甾醇、豆甾醇、谷甾烷醇、菜油甾烷醇含量并计算总植物甾醇含量;同时利用2002年居民营养与健康状况调查结果,初步测算我国城乡居民膳食植物甾醇的日平均摄入量。结果植物甾醇含量较高的植物食物包括植物油类、坚果种子类、豆类等;谷类中面粉植物甾醇含量远高于稻米,且粮谷类食品加工越精细,植物甾醇含量越低;蔬菜水果及薯类中植物甾醇含量较低。初步估计我国居民日均植物甾醇的摄入量为322.41mg/d,谷类食物和植物油类各提供约40%的膳食植物甾醇,其他类食物提供的比例较小。结论植物甾醇含量分析和摄入量估计对科学指导膳食有重要意义。在我国膳食模式下,增加面粉类、豆类、蔬菜水果类食物的摄入量,有助于提高居民植物甾醇摄入量和减少慢性病。     

Iron bioavailability and utilization in rats are lower from lime-treated corn flour than from wheat flour when they are fortified with different sources of iron

Although iron bioavailability from wheat flour fortified with iron has been widely studied, the bioavailability of lime-treated corn flour has not been evaluated sufficiently. We compared iron bioavailability and utilization of lime-treated corn flour and wheat flour supplemented with various iron sources. Bioavailability and utilization were determined in Sprague-Dawley rats using the iron balance and hemoglobin depletion-repletion methods. Rats were iron depleted by feeding them a low iron, casein diet for 10 d. During the repletion period, the rats were fed diets based on lime-treated corn flour or wheat flour, both supplemented with ferrous fumarate, ferrous sulfate, ferric citrate and reduced iron for 14 d. Hemoglobin was determined at the end of depletion and repletion periods. The phytate concentration was lower in wheat flour (114 mg/100g) than in lime-treated corn flour (501 mg/100g). Iron bioavailability and utilization by rats were higher from fortified and unfortified wheat flour than from the lime-treated corn flour counterparts. Iron utilization was greater in rats fed wheat flour supplemented with ferrous sulfate, followed by fumarate and citrate than in rats fed reduced iron. In lime-treated corn flour, iron utilization by rats fed unfortified flour and flour fortified with reduced iron did not differ, but utilization was higher in rats fed corn flour fortified with iron sulfate, fumarate and citrate than with reduced iron. We conclude that fortification of lime-treated corn flour with reduced iron has no effect on iron bioavailability or utilization, probably due to the high phytate content. Other iron compounds must be selected to fortify lime-treated corn flour when intended for public nutrition programs.     

常见谷类、豆类食物中植物甾醇含量分析

目的:对我国常见谷类、豆类食品中植物甾醇的含量和分布进行分析,并初步估计居民摄入量。方法:选择了25种谷类食物样品和16种豆类食物样品,气相色谱法分析了β-谷甾醇、菜油甾醇、豆甾醇、谷甾烷醇、菜油甾烷醇含量并计算总植物甾醇含量;同时利用2002年居民营养与健康状况调查结果,初步计算了我国居民谷类、豆类食品中植物甾醇的摄入量。结果:小麦面粉中植物甾醇含量普遍比大米要高,且粮谷类食品加工越精细,植物甾醇含量越低;豆类食品中也含有较多的植物甾醇,其中黄豆中植物甾醇含量高于其他豆类。初步估计我国居民从谷类中摄入的植物甾醇量130.76mg/标准人日,从豆类食物中摄取量为7.86mg。结论:植物甾醇含量分析和摄入量估计对科学指导膳食有重要意义,建议居民可通过摄入较多的面粉类和豆类食品来增加植物甾醇的摄入量,以降低慢性病的发生。     

智能一体化蒸馏——离子色谱法测定小麦粉中双乙酸钠

目的引入智能一体化蒸馏前处理方法,建立离子色谱-电导法测定小麦粉中双乙酸钠的检测方法。方法小麦粉样品采用智能一体化蒸馏仪蒸馏提取,蒸馏液用磷酸溶液调节pH值为3后定容,定容液经IonPac AS11阴离子交换柱分离,KOH淋洗液梯度淋洗,流速为1.0 ml/min,抑制性电导检测器检测,外标法峰面积定量。结果一体化蒸馏法可去除基质中不易挥发的离子,离子色谱-电导法可排除紫外末端吸收的干扰,提高了测定的准确性与灵敏度。该方法在0.004 mg/ml^0.05 mg/ml浓度时线性关系良好,相关系数(r)≥0.999,检出限为0.02 g/kg,采用低、中、高3个浓度加标,回收率在99.4%~102.2%,相对标准偏差(RSD)在1.37%~3.57%(n=6)。结论该方法操作简单快捷,重现性好,灵敏度高,可用于小麦粉中双乙酸钠含量的测定。     

2013年河南省部分食品中真菌毒素污染状况分析

摘要:目的　了解河南省食品中真菌毒素污染状况。方法　在全省18个省辖市采集5大类1875份食品样品,按照国家标准及相关检测方法检测食品中黄曲霉毒素B1、B2、G1、G2、M1和玉米赤霉烯酮的含量,检测结果按照GB 2761-2011《食品安全国家标准食品中真菌毒素限量》进行评价。结果　茶叶、乳制品、谷物及其制品、坚果及籽类和植物油中有不同程度的黄曲霉毒素检出,但均未超过我国限量标准;玉米面、通用小麦粉、专用小麦粉中玉米赤霉烯酮的检出率分别为24.4%、24%和13.64%,其中玉米面和通用小麦粉超标率分别为10.54%和1.23%。结论　我省食品中黄曲霉毒素污染水平总体较低,但是部分食品中玉米赤霉烯酮污染情况较为严重,应采取针对措施,以提高食品安全性。     

Use of sodium stearoyl lactylate and azodicarbonamide in wheat flour breads with added pea flour

Different amounts of sodium stearoyl lactylate (SSL) (X(1)) and azodicarbonamide (ADA) (X(2)) were analyzed to measure their effect on breadmaking using wheat flour with incorporation of pea flour (Pisum sativum) to the dough. The objective of the present work was to optimize the physical properties of dough (Y(1)Y(2)Y(3)Y(4)), the dough consistency during mixing (Y(5)Y(6)) and the baking performance (Y(7)Y(8)Y(9)). A central composite design and second-order models for Y(i) were employed. For dough physical properties and dough consistency during mixing, the best response was found when SSL varied between 0.5 and 1.5% and ADA between 110 and 170 ppm. For responses concerning the baking performance, better values for specific volume, crumb texture scores and bread score were obtained using SSL between 0.9 and 1.4% and ADA between 50 and 80 ppm. It is concluded that for baking with wheat flour replaced at about 10% with inactivated pea flour it should be advised to use SSL at levels close to 1% with ADA between 50 and 80 ppm.