GB5009.7-2016食品安全国家标准食品中还原糖的测定.pdf 21页

'中华人民共和国国家标准GB5009.7—2016食品安全国家标准食品中还原糖的测定2016-08-31发布2016-09-20实施中华人民共和国发布国家卫生和计划生育委员会 GB5009.7—2016前言本标准代替GB/T5009.7—2008《食品中还原糖的测定》、GB/T5513—2008《粮油检验粮食中还原糖和非还原糖测定》还原糖部分、NY/T1751—2009《甜菜还原糖的测定》。本标准与GB/T5009.7—2008相比,主要修改如下:———标准名称修改为“食品安全国家标准食品中还原糖的测定”;———将GB/T5009.7—2008与GB/T5513—2008还原糖部分进行了同类合并。Ⅰ GB5009.7—2016食品安全国家标准食品中还原糖的测定1范围本标准规定了食品中还原糖含量的测定方法。本标准第一法、第二法适用于食品中还原糖含量的测定。本标准第三法适用于小麦粉中还原糖含量的测定。本标准第四法适用于甜菜块根中还原糖含量的测定。第一法直接滴定法2原理试样经除去蛋白质后,以亚甲蓝作指示剂,在加热条件下滴定标定过的碱性酒石酸铜溶液(已用还原糖标准溶液标定),根据样品液消耗体积计算还原糖含量。3试剂和材料除非另有说明,本方法所用试剂均为分析纯,水为GB/T6682规定的三级水。3.1试剂3.1.1盐酸(HCl)。3.1.2硫酸铜(CuSO4·5H2O)。3.1.3亚甲蓝(C16H18ClN3S·3H2O)。3.1.4酒石酸钾钠(C4H4O6KNa·4H2O)。3.1.5氢氧化钠(NaOH)。3.1.6乙酸锌[Zn(CH3COO)2·2H2O]。3.1.7冰乙酸(C2H4O2)。3.1.8亚铁氰化钾[K4Fe(CN)6·3H2O]。3.2试剂配制3.2.1盐酸溶液(1+1,体积比):量取盐酸50mL,加水50mL混匀。3.2.2碱性酒石酸铜甲液:称取硫酸铜15g和亚甲蓝0.05g,溶于水中,并稀释至1000mL。3.2.3碱性酒石酸铜乙液:称取酒石酸钾钠50g和氢氧化钠75g,溶解于水中,再加入亚铁氰化钾4g,完全溶解后,用水定容至1000mL,贮存于橡胶塞玻璃瓶中。3.2.4乙酸锌溶液:称取乙酸锌21.9g,加冰乙酸3mL,加水溶解并定容于100mL。3.2.5亚铁氰化钾溶液(106g/L):称取亚铁氰化钾10.6g,加水溶解并定容至100mL。3.2.6氢氧化钠溶液(40g/L):称取氢氧化钠4g,加水溶解后,放冷,并定容至100mL。1 GB5009.7—20163.3标准品3.3.1葡萄糖(C6H12O6)CAS:50-99-7,纯度≥99%。3.3.2果糖(C6H12O6)CAS:57-48-7,纯度≥99%。3.3.3乳糖(含水)(C6H12O6·H2O)CAS:5989-81-1,纯度≥99%。3.3.4蔗糖(C12H22O11)CAS:57-50-1,纯度≥99%。3.4标准溶液配制3.4.1葡萄糖标准溶液(1.0mg/mL):准确称取经过98℃~100℃烘箱中干燥2h后的葡萄糖1g,加水溶解后加入盐酸溶液5mL,并用水定容至1000mL。此溶液每毫升相当于1.0mg葡萄糖。3.4.2果糖标准溶液(1.0mg/mL):准确称取经过98℃~100℃干燥2h的果糖1g,加水溶解后加入盐酸溶液5mL,并用水定容至1000mL。此溶液每毫升相当于1.0mg果糖。3.4.3乳糖标准溶液(1.0mg/mL):准确称取经过94℃~98℃干燥2h的乳糖(含水)1g,加水溶解后加入盐酸溶液5mL,并用水定容至1000mL。此溶液每毫升相当于1.0mg乳糖(含水)。3.4.4转化糖标准溶液(1.0mg/mL):准确称取1.0526g蔗糖,用100mL水溶解,置具塞锥形瓶中,加盐酸溶液5mL,在68℃~70℃水浴中加热15min,放置至室温,转移至1000mL容量瓶中并加水定容至1000mL,每毫升标准溶液相当于1.0mg转化糖。4仪器和设备4.1天平:感量为0.1mg。4.2水浴锅。4.3可调温电炉。4.4酸式滴定管:25mL。5分析步骤5.1试样制备5.1.1含淀粉的食品:称取粉碎或混匀后的试样10g~20g(精确至0.001g),置250mL容量瓶中,加水200mL,在45℃水浴中加热1h,并时时振摇,冷却后加水至刻度,混匀,静置,沉淀。吸取200.0mL上清液置于另一250mL容量瓶中,缓慢加入乙酸锌溶液5mL和亚铁氰化钾溶液5mL,加水至刻度,混匀,静置30min,用干燥滤纸过滤,弃去初滤液,取后续滤液备用。5.1.2酒精饮料:称取混匀后的试样100g(精确至0.01g),置于蒸发皿中,用氢氧化钠溶液中和至中性,在水浴上蒸发至原体积的1/4后,移入250mL容量瓶中,缓慢加入乙酸锌溶液5mL和亚铁氰化钾溶液5mL,加水至刻度,混匀,静置30min,用干燥滤纸过滤,弃去初滤液,取后续滤液备用。2 GB5009.7—20165.1.3碳酸饮料:称取混匀后的试样100g(精确至0.01g)于蒸发皿中,在水浴上微热搅拌除去二氧化碳后,移入250mL容量瓶中,用水洗涤蒸发皿,洗液并入容量瓶,加水至刻度,混匀后备用。5.1.4其他食品:称取粉碎后的固体试样2.5g~5g(精确至0.001g)或混匀后的液体试样5g~25g(精确至0.001g),置250mL容量瓶中,加50mL水,缓慢加入乙酸锌溶液5mL和亚铁氰化钾溶液5mL,加水至刻度,混匀,静置30min,用干燥滤纸过滤,弃去初滤液,取后续滤液备用。5.2碱性酒石酸铜溶液的标定吸取碱性酒石酸铜甲液5.0mL和碱性酒石酸铜乙液5.0mL,于150mL锥形瓶中,加水10mL,加入玻璃珠2粒~4粒,从滴定管中加葡萄糖(3.4.1)[或其他还原糖标准溶液(3.4.2,或3.4.3,或3.4.4)]约9mL,控制在2min中内加热至沸,趁热以每2秒1滴的速度继续滴加葡萄糖[或其他还原糖标准溶液(3.4.2,或3.4.3,或3.4.4)],直至溶液蓝色刚好褪去为终点,记录消耗葡萄糖(或其他还原糖标准溶液)的总体积,同时平行操作3份,取其平均值,计算每10mL(碱性酒石酸甲、乙液各5mL)碱性酒石酸铜溶液相当于葡萄糖(或其他还原糖)的质量(mg)。注:也可以按上述方法标定4mL~20mL碱性酒石酸铜溶液(甲、乙液各半)来适应试样中还原糖的浓度变化。5.3试样溶液预测吸取碱性酒石酸铜甲液5.0mL和碱性酒石酸铜乙液5.0mL于150mL锥形瓶中,加水10mL,加入玻璃珠2粒~4粒,控制在2min内加热至沸,保持沸腾以先快后慢的速度,从滴定管中滴加试样溶液,并保持沸腾状态,待溶液颜色变浅时,以1滴/2s的速度滴定,直至溶液蓝色刚好褪去为终点,记录样品溶液消耗体积。注:当样液中还原糖浓度过高时,应适当稀释后再进行正式测定,使每次滴定消耗样液的体积控制在与标定碱性酒石酸铜溶液时所消耗的还原糖标准溶液的体积相近,约10mL左右,结果按式(1)计算;当浓度过低时则采取直接加入10mL样品液,免去加水10mL,再用还原糖标准溶液滴定至终点,记录消耗的体积与标定时消耗的还原糖标准溶液体积之差相当于10mL样液中所含还原糖的量,结果按式(2)计算。5.4试样溶液测定吸取碱性酒石酸铜甲液5.0mL和碱性酒石酸铜乙液5.0mL,置于150mL锥形瓶中,加水10mL,加入玻璃珠2粒~4粒,从滴定管滴加比预测体积少1mL的试样溶液至锥形瓶中,控制在2min内加热至沸,保持沸腾继续以1滴/2s的速度滴定,直至蓝色刚好褪去为终点,记录样液消耗体积,同法平行操作三份,得出平均消耗体积(V)。6分析结果的表述试样中还原糖的含量(以某种还原糖计)按式(1)计算:m1X=×100…………………………(1)m×F×V/250×1000式中:X———试样中还原糖的含量(以某种还原糖计),单位为克每百克(g/100g);m———碱性酒石酸铜溶液(甲、乙液各半)相当于某种还原糖的质量,单位为毫克(mg);1m———试样质量,单位为克(g);F———系数,对5.1.1、5.1.3、5.1.4为1;5.1.2为0.80;V———测定时平均消耗试样溶液体积,单位为毫升(mL);250———定容体积,单位毫升(mL);3 GB5009.7—20161000———换算系数。当浓度过低时,试样中还原糖的含量(以某种还原糖计)按式(2)计算:m2X=×100…………………………(2)m×F×10/250×1000式中:X———试样中还原糖的含量(以某种还原糖计),单位为克每百克(g/100g);m———标定时体积与加入样品后消耗的还原糖标准溶液体积之差相当于某种还原糖的质量,2单位为毫克(mg);m———试样质量,单位为克(g);F———系数,对5.1.1、5.1.3、5.1.4为1;5.1.2为0.80;10———样液体积,单位毫升(mL);250———定容体积,单位毫升(mL);1000———换算系数。还原糖含量≥10g/100g时,计算结果保留三位有效数字;还原糖含量<10g/100g时,计算结果保留两位有效数字。7精密度在重复性条件下获得的两次独立测定结果的绝对差值不得超过算术平均值的5%。8其他当称样量为5g时,定量限为0.25g/100g。第二法高锰酸钾滴定法9原理试样经除去蛋白质后,其中还原糖把铜盐还原为氧化亚铜,加硫酸铁后,氧化亚铜被氧化为铜盐,经高锰酸钾溶液滴定氧化作用后生成的亚铁盐,根据高锰酸钾消耗量,计算氧化亚铜含量,再查表得还原糖量。10试剂和材料除非另有说明,本方法所用试剂均为分析纯,水为GB/T6682规定的三级水。10.1试剂10.1.1盐酸(HCl)。10.1.2氢氧化钠(NaOH)。10.1.3硫酸铜(CuSO4·5H2O)。10.1.4硫酸(H2SO4)。10.1.5硫酸铁[Fe2(SO4)3]。10.1.6酒石酸钾钠(C4H4O6KNa·4H2O)。4 GB5009.7—201610.2试剂配制10.2.1盐酸溶液(3mol/L):量取盐酸30mL,加水稀释至120mL。10.2.2碱性酒石酸铜甲液:称取硫酸铜34.639g,加适量水溶解,加硫酸0.5mL,再加水稀释至500mL,用精制石棉过滤。10.2.3碱性酒石酸铜乙液:称取酒石酸钾钠173g与氢氧化钠50g,加适量水溶解,并稀释至500mL,用精制石棉过滤,贮存于橡胶塞玻璃瓶内。10.2.4氢氧化钠溶液(40g/L):称取氢氧化钠4g,加水溶解并稀释至100mL。10.2.5硫酸铁溶液(50g/L):称取硫酸铁50g,加水200mL溶解后,慢慢加入硫酸100mL,冷后加水稀释至1000mL。10.2.6精制石棉:取石棉先用盐酸溶液浸泡2d~3d,用水洗净,再加氢氧化钠溶液浸泡2d~3d,倾去溶液,再用热碱性酒石酸铜乙液浸泡数小时,用水洗净。再以盐酸溶液浸泡数小时,以水洗至不呈酸性。然后加水振摇,使成细微的浆状软纤维,用水浸泡并贮存于玻璃瓶中,即可作填充古氏坩埚用。10.3标准品高锰酸钾(KMnO4),CAS:7722-64-7,优级纯或以上等级。10.4标准溶液配制高锰酸钾标准滴定溶液[c(1/5KMnO4)=0.1000mol/L]:按GB/T601配制与标定。11仪器和设备11.1天平:感量为0.1mg。11.2水浴锅。11.3可调温电炉。11.4酸式滴定管:25mL。11.525mL古氏坩埚或G4垂融坩埚。11.6真空泵。12分析步骤12.1试样处理12.1.1含淀粉的食品:称取粉碎或混匀后的试样10g~20g(精确至0.001g),置250mL容量瓶中,加水200mL,在45℃水浴中加热1h,并时时振摇。冷却后加水至刻度,混匀,静置。吸取200.0mL上清液置另一250mL容量瓶中,加碱性酒石酸铜甲液10mL及氢氧化钠溶液4mL,加水至刻度,混匀。静置30min,用干燥滤纸过滤,弃去初滤液,取后续滤液备用。12.1.2酒精饮料:称取100g(精确至0.01g)混匀后的试样,置于蒸发皿中,用氢氧化钠溶液中和至中性,在水浴上蒸发至原体积的1/4后,移入250mL容量瓶中。加水50mL,混匀。加碱性酒石酸铜甲液10mL及氢氧化钠溶液4mL,加水至刻度,混匀。静置30min,用干燥滤纸过滤,弃去初滤液,取后续滤液备用。12.1.3碳酸饮料:称取100g(精确至0.001g)混匀后的试样,试样置于蒸发皿中,在水浴上除去二氧化碳后,移入250mL容量瓶中,并用水洗涤蒸发皿,洗液并入容量瓶中,再加水至刻度,混匀后,备用。5 GB5009.7—201612.1.4其他食品:称取粉碎后的固体试样2.5g~5.g(精确至0.001g)或混匀后的液体试样25g~50g(精确至0.001g),置250mL容量瓶中,加水50mL,摇匀后加碱性酒石酸铜甲液10mL及氢氧化钠溶液4mL,加水至刻度,混匀。静置30min,用干燥滤纸过滤,弃去初滤液,取后续滤液备用。12.2试样溶液的测定吸取处理后的试样溶液50.0mL,于500mL烧杯内,加入碱性酒石酸铜甲液25mL及碱性酒石酸铜乙液25mL,于烧杯上盖一表面皿,加热,控制在4min内沸腾,再精确煮沸2min,趁热用铺好精制石棉的古氏坩埚(或G4垂融坩埚)抽滤,并用60℃热水洗涤烧杯及沉淀,至洗液不呈碱性为止。将古氏坩埚(或G4垂融坩埚)放回原500mL烧杯中,加硫酸铁溶液25mL、水25mL,用玻棒搅拌使氧化亚铜完全溶解,以高锰酸钾标准溶液滴定至微红色为终点。同时吸取水50mL,加入与测定试样时相同量的碱性酒石酸铜甲液、乙液、硫酸铁溶液及水,按同一方法做空白试验。13分析结果的表述试样中还原糖质量相当于氧化亚铜的质量,按式(3)计算:X0=(V-V0)×c×71.54…………………………(3)式中:X0———试样中还原糖质量相当于氧化亚铜的质量,单位为毫克(mg);V———测定用试样液消耗高锰酸钾标准溶液的体积,单位为毫升(mL);V0———试剂空白消耗高锰酸钾标准溶液的体积,单位为毫升(mL);c———高锰酸钾标准溶液的实际浓度,单位为摩尔每升(mol/L);71.54———1mL高锰酸钾标准溶液[c(1/5)KMnO4]=1.000mol/L)相当于氧化亚铜的质量,单位为毫克(mg)。根据式中计算所得氧化亚铜质量,查表A.1,再计算试样中还原糖含量,按式(4)计算:m3X=×100…………………………(4)m4×V/250×1000式中:X———试样中还原糖的含量,单位为克每百克(g/100g);m3———X0查附录A之表1得还原糖质量,单位为毫克(mg);m———试样质量或体积,单位为克或毫升(g或mL);4V———测定用试样溶液的体积,单位为毫升(mL);250———试样处理后的总体积,单位为毫升(mL)。还原糖含量≥10g/100g时,计算结果保留三位有效数字;还原糖含量<10g/100g时,计算结果保留两位有效数字。14精密度在重复性条件下获得的两次独立测定结果的绝对差值不得超过算术平均值的10%。6 GB5009.7—201615其他当称样量为5g时,定量限为0.5g/100g。第三法铁氰化钾法16原理还原糖在碱性溶液中将铁氰化钾还原为亚铁氰化钾,还原糖本身被氧化为相应的糖酸。过量的铁氰化钾在乙酸的存在下,与碘化钾作用下析出碘,析出的碘以硫代硫酸钠标准溶液滴定。通过计算氧化还原糖时所用的铁氰化钾的量,查表A.2得试样中还原糖的含量。17试剂除非另有说明,本方法所用试剂均为分析纯,水为GB/T6682规定的三级水。17.1试剂17.1.195%乙醇。17.1.2冰乙酸(NaOH)。17.1.3无水乙酸钠(NaOH)。17.1.4硫酸(H2SO4)。17.1.5钨酸钠(Na2WO4·2H2O)。17.1.6铁氰化钾[KFe(CN)6]。17.1.7碳酸钠(Na2CO3)。17.1.8氯化钾(KCl)。17.1.9硫酸锌(ZnSO4)。17.1.10碘化钾(KI)。17.1.11氢氧化钠(NaOH)。17.1.12可溶性淀粉。17.2试剂配制17.2.1乙酸缓冲液:将冰乙酸3.0mL、无水乙酸钠6.8g和浓硫酸4.5mL混合溶解,然后稀释至1000mL。17.2.2钨酸钠溶液(12.0%):将钨酸钠12.0g溶于100mL水中。17.2.3碱性铁氰化钾溶液(0.1mol/L):将铁氰化钾32.9g与碳酸钠44.0g溶于1000mL水中。17.2.4乙酸盐溶液:将氯化钾70.0g和硫酸锌40.0g溶于750mL水中,然后缓慢加入200mL冰乙酸,再用水稀释至1000mL,混匀。17.2.5碘化钾溶液(10%):称取碘化钾10.0g溶于100mL水中,再加一滴饱和氢氧化钠溶液。17.2.6淀粉溶液(1%):称取可溶性淀粉1.0g,用少量水润湿调和后,缓慢倒入100mL沸水中,继续煮沸直至溶液透明。17.2.7硫代硫酸钠溶液(0.1mol/L):按GB/T601配制与标定。7 GB5009.7—201618仪器和设备18.1分析天平:分度值0.0001g。18.2振荡器。18.3试管:直径1.8cm~2.0cm,高约18cm。18.4水浴锅。18.5电炉:2000W。18.6微量滴定管:5mL或10mL。19分析步骤19.1试样制备称取试样5g(精确至0.001g)于100mL磨口锥形瓶中。倾斜锥形瓶以便所有试样粉末集中于一侧,用5mL95%乙醇浸湿全部试样,再加入50mL乙酸缓冲液,振荡摇匀后立即加入2mL12.0%钨酸钠溶液,在振荡器上混合振摇5min。将混合液过滤,弃去最初几滴滤液,收集滤液于干净锥形瓶中,此滤液即为样品测定液。同时做空白实验。19.2试样溶液的测定19.2.1氧化:精确吸取样品液5mL于试管中,再精确加入5mL碱性铁氰化钾溶液,混合后立即将试管浸入剧烈沸腾的水浴中,并确保试管内液面低于沸水液面下3cm~4cm,加热20min后取出,立即用冷水迅速冷却。19.2.2滴定:将试管内容物倾入100mL锥形瓶中,用25mL乙酸盐溶液荡洗试管一并倾入锥形瓶中,加5mL10%碘化钾溶液,混匀后,立即用0.1mol/L硫代硫酸钠溶液滴定至淡黄色,再加1mL淀粉溶液,继续滴定直至溶液蓝色消失,记下消耗硫代硫酸钠溶液体积(V1)。19.2.3空白试验:吸取空白液5mL,代替样品液按19.2.1和19.2.2操作,记下消耗的硫代硫酸钠溶液体积(V0)。20分析结果表述根据氧化样品液中还原糖所需0.1mol/L铁氰化钾溶液的体积查表A.1,即可查得试样中还原糖(以麦芽糖计算)的质量分数。铁氰化钾溶液体积(V)按式(5)计算:3(V0-V1)×cV3=…………………………(5)0.1式中:V3———氧化样品液中还原糖所需0.1mol/L铁氰化钾溶液的体积,单位为毫升(mL);V0———滴定空白液消耗0.1mol/L硫代硫酸钠溶液的体积,单位为毫升(mL);V1———滴定样品液消耗0.1mol/L硫代硫酸钠溶液的体积,单位为毫升(mL);c———硫代硫酸钠溶液实际浓度,单位为摩尔每升(mol/L)。计算结果保留小数点后两位。0.1mol/L铁氰化钾体积与还原糖含量对照可查表A.2。注:还原糖含量以麦芽糖计算。8 GB5009.7—201621精密度在重复性条件下,获得的两次独立测定结果的绝对差值不得超过算术平均值的10%。第四法奥氏试剂滴定法22原理在沸腾条件下,还原糖与过量奥氏试剂反应生成相当量的Cu2O沉淀,冷却后加入盐酸使溶液呈酸性,并使Cu2O沉淀溶解。然后加入过量碘溶液进行氧化,用硫代硫酸钠溶液滴定过量的碘,其反应式如下:C6H12O6+2C4H2O6KNaCu+2H2O→C6H12O7+2C4H4O6KNa+CuO↓葡萄糖或果糖络合物葡萄糖酸酒石酸钾钠氧化亚铜Cu2O↓+2HCl→2CuCl+H2O2CuCl+2KI+I2→2CuI2+2KClI2(过剩的)+2Na2S2O3→Na2S4O6+2NaI硫代硫酸钠标准溶液空白试验滴定量减去其样品试验滴定量得到一个差值,由此差值便可计算出还原糖的量。23试剂和材料除非另有说明,本方法所用试剂均为分析纯,水为GB/T6682规定的三级水。23.1试剂23.1.1盐酸(HCl)。23.1.2硫酸铜(CuSO4·5H2O)。23.1.3酒石酸钾钠(C4H4O6KNa·4H2O)。23.1.4无水碳酸钠(Na2CO3)。23.1.5冰乙酸(C2H4O2)。23.1.6磷酸氢二钠(Na2HPO4·12H2O)。23.1.7碘化钾(KI)。23.1.8乙酸锌[Zn(CH3COO)2·2H2O]。23.1.9亚铁氰化钾[K4Fe(CN)6·3H2O]。23.1.10可溶性淀粉。23.1.11粉状碳酸钙(CaCO3)。23.2试剂配制23.2.1盐酸溶液(6mol/L):吸取盐酸50.0mL,加入已装入30mL水的烧杯中,慢慢加水稀释至100mL。23.2.2盐酸溶液(1mol/L):吸取盐酸84.0mL,加入已装入200mL水的烧杯中,慢慢加水稀释至1000mL。9 GB5009.7—201623.2.3奥氏试剂:分别称取硫酸铜5.0g、酒石酸钾钠300g,无水碳酸钠10.0g、磷酸氢二钠50.0g,稀释至1000mL,用细孔砂芯玻璃漏斗或硅藻土或活性炭过滤,贮于棕色试剂瓶中。23.2.4碘化钾溶液(250g/L):称取碘化钾25.0g,溶于水,移入100mL容量瓶中,用水稀释至刻度,摇匀。23.2.5乙酸锌溶液:称取乙酸锌21.9g,加冰乙酸3mL,加水溶解并定容于100mL。23.2.6亚铁氰化钾溶液(106g/L):称取亚铁氰化钾10.6g,加水溶解并定容至100mL。23.2.7淀粉指示剂(5g/L):称取可溶性淀粉0.50g,加冷水10mL调匀,搅拌下注入90mL沸水中,再微沸2min,冷却。溶液于使用前制备。23.3标准品23.3.1硫代硫酸钠(Na2S2O3),CAS:7772-98-7,优级纯或以上等级。23.3.2碘(I2),CAS:7553-56-2,12190-71-5,优级纯或以上等级。23.3.3碘化钾(KI),CAS:7681-11-0,优级纯或以上等级。23.4标准溶液配制23.4.1硫代硫酸钠标准滴定储备液[c(Na2S2O3)=0.1mol/L]:按GB/T601配制与标定。也可使用商品化的产品。23.4.2硫代硫酸钠标准滴定溶液[c(Na2S2O3)=0.0323mol/L]:精确吸取硫代硫酸钠标准滴定储备液(23.4.1)32.30mL,移入100mL容量瓶中,用水稀释至刻度。校正系数按式(6)计算cK=…………………………(6)0.0323式中:c———硫代硫酸钠标准溶液的浓度,单位为摩尔每升(mol/L)。23.4.3碘溶液标准滴定储备液[c(I2)=0.1mol/L]:按GB/T601配置与标定。也可使用商品化的产品。23.4.4碘标准滴定溶液:[c(I2)=0.01615mol/L]。精确吸取碘溶液标准滴定储备液(23.4.3)16.15mL,移入100mL容量瓶中,用水稀释至刻度。24仪器和设备24.1天平:感量为0.1mg。24.2水浴锅。24.3可调温电炉或性能相当的加热器具。24.4酸式滴定管:25mL。25分析步骤25.1试样溶液的制备25.1.1将备检样品清洗干净。取100g(精确至0.01g)样品,放入高速捣碎机中,用移液管移入100mL的水,以不低于12000r/min的转速将其捣成1∶1的匀浆。25.1.2称取匀浆样品25g(精确至0.001g),于500mL具塞锥形瓶中(含有机酸较多的试样加粉状碳酸钙0.5g~2.0g调至中性),加水调整体积约为200mL。置80℃±2℃水浴保温30min,其间摇动数次,取出加入乙酸锌溶液5mL和亚铁氰化钾溶液5mL,冷却至室温后,转入250mL容量瓶,用水定10 GB5009.7—2016容至刻度。摇匀,过滤,澄清试样溶液备用。25.2Cu2O沉淀生成吸取试样溶液20.00mL(若样品还原糖含量较高时,可适当减少取样体积,并补加水至20mL,使试样溶液中还原糖的量不超过20mg),加入250mL锥形瓶中。然后加入奥氏试剂50.00mL,充分混合,用小漏斗盖上,在电炉上加热,控制在3min中内加热至沸,并继续准确煮沸5.0min,将锥形瓶静置于冷水中冷却至室温。25.3碘氧化反应取出锥形瓶,加入冰乙酸1.0mL,在不断摇动下,准确加入碘标准滴定溶液5.00mL~30.00mL,其数量以确保碘溶液过量为准,用量筒沿锥形瓶壁快速加入盐酸15mL,立即盖上小烧杯,放置约2min,不时摇动溶液。25.4滴定过量碘用硫代硫酸钠标准滴定溶液滴定过量的碘,滴定至溶液呈黄绿色出现时,加入淀粉指示剂2mL,继续滴定溶液至蓝色褪尽为止,记录消耗的硫代硫酸钠标准滴定溶液体积(V4)。25.5空白试验按上述步骤进行空白试验(V3),除了不加试样溶液外,操作步骤和应用的试剂均与测定时相同。26分析结果表述试样品的还原糖按式(7)计算。0.001X=K×(V3-V4)××100…………………………(7)m×V5/250式中:X———试样中还原糖的含量,单位为克每百克(g/100g);K———硫代硫酸钠标准滴定溶液[c(Na2S2O3)=0.0323mol/L]校正系数;V3———空白试验滴定消耗的硫代硫酸钠标准滴定溶液体积,单位为毫升(mL);V4———试样溶液消耗的硫代硫酸钠标准滴定溶液体积,单位为毫升(mL);V5———所取试样溶液的体积,单位为毫升(mL);m———试样的质量,单位为克(g);250———试样浸提稀释后的总体积,单位为毫升(mL)。计算结果保留两位有效数字。27精密度在重复性条件下获得的两次独立测定结果的绝对差值不得超过算术平均值的5%。28其他当称样量为5g时,定量限为0.25g/100g。11 GB5009.7—2016附录AA.1相当于氧化亚铜质量的葡萄糖、果糖、乳糖、转化糖质量表相当于氧化亚铜质量的葡萄糖、果糖、乳糖、转化糖质量表见表A.1。表A.1相当于氧化亚铜质量的葡萄糖、果糖、乳糖、转化糖质量表单位为毫克乳糖乳糖氧化亚铜葡萄糖果糖转化糖氧化亚铜葡萄糖果糖转化糖(含水)(含水)11.34.65.17.75.240.517.219.027.618.312.45.15.68.55.741.717.719.528.418.913.55.66.19.36.242.818.220.129.119.414.66.06.710.06.743.918.720.629.919.915.86.57.210.87.245.019.221.130.620.416.97.07.711.57.746.219.721.731.420.918.07.58.312.38.247.320.122.232.221.419.18.08.813.18.748.420.622.832.921.920.38.59.313.89.249.521.123.333.722.421.48.99.914.69.750.721.623.834.522.922.59.410.415.410.251.822.124.435.223.523.69.910.916.110.752.922.624.936.024.024.810.411.516.911.254.023.125.436.824.525.910.912.017.711.755.223.626.037.525.027.011.412.518.412.356.324.126.538.325.528.111.913.119.212.857.424.627.139.126.029.312.313.619.913.358.525.127.639.826.530.412.814.220.713.859.725.628.240.627.031.513.314.721.514.360.826.128.741.427.632.613.815.222.214.861.926.529.242.128.133.814.315.823.015.363.027.029.842.928.634.914.816.323.815.864.227.530.343.729.136.015.316.824.516.365.328.030.944.429.637.215.717.425.316.866.428.531.445.230.138.316.217.926.117.367.629.031.946.030.639.416.718.426.817.868.729.532.546.731.212 GB5009.7—2016表A.1(续)单位为毫克乳糖乳糖氧化亚铜葡萄糖果糖转化糖氧化亚铜葡萄糖果糖转化糖(含水)(含水)69.830.033.047.531.7107.046.551.172.848.870.930.533.648.332.2108.147.051.673.649.472.131.034.149.032.7109.247.552.274.449.973.231.534.749.833.2110.348.052.775.150.474.332.035.250.633.7111.548.553.375.950.975.432.535.851.334.3112.649.053.876.751.576.633.036.352.134.8113.749.554.477.452.077.733.536.852.935.3114.850.054.978.252.578.834.037.453.635.8116.050.655.579.053.079.934.537.954.436.3117.151.156.079.753.681.135.038.555.236.8118.251.656.680.554.182.235.539.055.937.4119.352.157.181.354.683.336.039.656.737.9120.552.657.782.155.284.436.540.157.538.4121.653.158.282.855.785.637.040.758.238.9122.753.658.883.656.286.737.541.259.039.4123.854.159.384.456.787.838.041.759.840.0125.054.659.985.157.388.938.542.360.540.5126.155.160.485.957.890.139.042.861.341.0127.255.661.086.758.391.239.543.462.141.5128.356.161.687.458.992.340.043.962.842.0129.556.762.188.259.493.440.544.563.642.6130.657.262.789.059.994.641.045.064.443.1131.757.763.289.860.495.741.545.665.143.6132.858.263.890.561.096.842.046.165.944.1134.058.764.391.361.597.942.546.766.744.7135.159.264.992.162.099.143.047.267.445.2136.259.765.492.862.6100.243.547.868.245.7137.460.266.093.663.1101.344.048.369.046.2138.560.766.594.463.6102.544.548.969.746.7139.661.367.195.264.2103.645.049.470.547.3140.761.867.795.964.7104.745.550.071.347.8141.962.368.296.765.2105.846.050.572.148.3143.062.868.897.565.813 GB5009.7—2016表A.1(续)单位为毫克乳糖乳糖氧化亚铜葡萄糖果糖转化糖氧化亚铜葡萄糖果糖转化糖(含水)(含水)144.163.369.398.266.3181.380.487.8123.784.0145.263.869.999.066.8182.481.088.4124.584.6146.464.370.499.867.4183.581.589.0125.385.1147.564.971.0100.667.9184.582.089.5126.085.7148.665.471.6101.368.4185.882.590.1126.886.2149.765.972.1102.169.0186.983.190.6127.686.8150.966.472.7102.969.5188.083.691.2128.487.3152.066.973.2103.670.0189.184.191.8129.187.8153.167.473.8104.470.6190.384.692.3129.988.4154.268.074.3105.271.1191.485.292.9130.788.9155.468.574.9106.071.6192.585.793.5131.589.5156.569.075.5106.772.2193.686.294.0132.290.0157.669.576.0107.572.7194.886.794.6133.090.6158.770.076.6108.373.2195.987.395.2133.891.1159.970.577.1109.073.8197.087.895.7134.691.7161.071.177.7109.874.3198.188.396.3135.392.2162.171.678.3110.674.9199.388.996.9136.192.8163.272.178.8111.475.4200.489.497.4136.993.3164.472.679.4112.175.9201.589.998.0137.793.8165.573.180.0112.976.5202.790.498.6138.494.4166.673.780.5113.777.0203.891.099.2139.294.9167.874.281.1114.477.6204.991.599.7140.095.5168.974.781.6115.278.1206.092.0100.3140.896.0170.075.282.2116.078.6207.292.6100.9141.596.6171.175.782.8116.879.2208.393.1101.4142.397.1172.376.383.3117.579.7209.493.6102.0143.197.7173.476.883.9118.380.3210.594.2102.6143.998.2174.577.384.4119.180.8211.794.7103.1144.698.8175.677.885.0119.981.3212.895.2103.7145.499.3176.878.385.6120.681.9213.995.7104.3146.299.9177.978.986.1121.482.4215.096.3104.8147.0100.4179.079.486.7122.283.0216.296.8105.4147.7101.0180.179.987.3122.983.5217.397.3106.0148.5101.514 GB5009.7—2016表A.1(续)单位为毫克乳糖乳糖氧化亚铜葡萄糖果糖转化糖氧化亚铜葡萄糖果糖转化糖(含水)(含水)218.497.9106.6149.3102.1255.6115.7125.5174.9120.4219.598.4107.1150.1102.6256.7116.2126.1175.7121.0220.798.9107.7150.8103.2257.8116.7126.7176.5121.6221.899.5108.3151.6103.7258.9117.3127.3177.3122.1222.9100.0108.8152.4104.3260.1117.8127.9178.1122.7224.0100.5109.4153.2104.8261.2118.4128.4178.8123.3225.2101.1110.0153.9105.4262.3118.9129.0179.6123.8226.3101.6110.6154.7106.0263.4119.5129.6180.4124.4227.4102.2111.1155.5106.5264.6120.0130.2181.2124.9228.5102.7111.7156.3107.1265.7120.6130.8181.9125.5229.7103.2112.3157.0107.6266.8121.1131.3182.7126.1230.8103.8112.9157.8108.2268.0121.7131.9183.5126.6231.9104.3113.4158.6108.7269.1122.2132.5184.3127.2233.1104.8114.0159.4109.3270.2122.7133.1185.1127.8234.2105.4114.6160.2109.8271.3123.3133.7185.8128.3235.3105.9115.2160.9110.4272.5123.8134.2186.6128.9236.4106.5115.7161.7110.9273.6124.4134.8187.4129.5237.6107.0116.3162.5111.5274.7124.9135.4188.2130.0238.7107.5116.9163.3112.1275.8125.5136.0189.0130.6239.8108.1117.5164.0112.6277.0126.0136.6189.7131.2240.9108.6118.0164.8113.2278.1126.6137.2190.5131.7242.1109.2118.6165.6113.7279.2127.1137.7191.3132.3243.1109.7119.2166.4114.3280.3127.7138.3192.1132.9244.3110.2119.8167.1114.9281.5128.2138.9192.9133.4245.4110.8120.3167.9115.4282.6128.8139.5193.6134.0246.6111.3120.9168.7116.0283.7129.3140.1194.4134.6247.7111.9121.5169.5116.5284.8129.9140.7195.2135.1248.8112.4122.1170.3117.1286.0130.4141.3196.0135.7249.9112.9122.6171.0117.6287.1131.0141.8196.8136.3251.1113.5123.2171.8118.2288.2131.6142.4197.5136.8252.2114.0123.8172.6118.8289.3132.1143.0198.3137.4253.3114.6124.4173.4119.3290.5132.7143.6199.1138.0254.4115.1125.0174.2119.9291.6133.2144.2199.9138.615 GB5009.7—2016表A.1(续)单位为毫克乳糖乳糖氧化亚铜葡萄糖果糖转化糖氧化亚铜葡萄糖果糖转化糖(含水)(含水)292.7133.8144.8200.7139.1329.9152.2164.3226.5158.1293.8134.3145.4201.4139.7331.0152.8164.9227.3158.7295.0134.9145.9202.2140.3332.1153.4165.4228.0159.3296.1135.4146.5203.0140.8333.3153.9166.0228.8159.9297.2136.0147.1203.8141.4334.4154.5166.6229.6160.5298.3136.5147.7204.6142.0335.5155.1167.2230.4161.0299.5137.1148.3205.3142.6336.6155.6167.8231.2161.6300.6137.7148.9206.1143.1337.8156.2168.4232.0162.2301.7138.2149.5206.9143.7338.9156.8169.0232.7162.8302.9138.8150.1207.7144.3340.0157.3169.6233.5163.4304.0139.3150.6208.5144.8341.1157.9170.2234.3164.0305.1139.9151.2209.2145.4342.3158.5170.8235.1164.5306.2140.4151.8210.0146.0343.4159.0171.4235.9165.1307.4141.0152.4210.8146.6344.5159.6172.0236.7165.7308.5141.6153.0211.6147.1345.6160.2172.6237.4166.3309.6142.1153.6212.4147.7346.8160.7173.2238.2166.9310.7142.7154.2213.2148.3347.9161.3173.8239.0167.5311.9143.2154.8214.0148.9349.0161.9174.4239.8168.0313.0143.8155.4214.7149.4350.1162.5175.0240.6168.6314.1144.4156.0215.5150.0351.3163.0175.6241.4169.2315.2144.9156.5216.3150.6352.4163.6176.2242.2169.8316.4145.5157.1217.1151.2353.5164.2176.8243.0170.4317.5146.0157.7217.9151.8354.6164.7177.4243.7171.0318.6146.6158.3218.7152.3355.8165.3178.0244.5171.6319.7147.2158.9219.4152.9356.9165.9178.6245.3172.2320.9147.7159.5220.2153.5358.0166.5179.2246.1172.8322.0148.3160.1221.0154.1359.1167.0179.8246.9173.3323.1148.8160.7221.8154.6360.3167.6180.4247.7173.9324.2149.4161.3222.6155.2361.4168.2181.0248.5174.5325.4150.0161.9223.3155.8362.5168.8181.6249.2175.1326.5150.5162.5224.1156.4363.6169.3182.2250.0175.7327.6151.1163.1224.9157.0364.8169.9182.8250.8176.3328.7151.7163.7225.7157.5365.9170.5183.4251.6176.916 GB5009.7—2016表A.1(续)单位为毫克乳糖乳糖氧化亚铜葡萄糖果糖转化糖氧化亚铜葡萄糖果糖转化糖(含水)(含水)367.0171.1184.0252.4177.5398.5187.3201.0274.4194.2368.2171.6184.6253.2178.1399.7187.9201.6275.2194.8369.3172.2185.2253.9178.7400.8188.5202.2276.0195.4370.4172.8185.8254.7179.2401.9189.1202.8276.8196.0371.5173.4186.4255.5179.8403.1189.7203.4277.6196.6372.7173.9187.0256.3180.4404.2190.3204.0278.4197.2373.8174.5187.6257.1181.0405.3190.9204.7279.2197.8374.9175.1188.2257.9181.6406.4191.5205.3280.0198.4376.0175.7188.8258.7182.2407.6192.0205.9280.8199.0377.2176.3189.4259.4182.8408.7192.6206.5281.6199.6378.3176.8190.1260.2183.4409.8193.2207.1282.4200.2379.4177.4190.7261.0184.0410.9193.8207.7283.2200.8380.5178.0191.3261.8184.6412.1194.4208.3284.0201.4381.7178.6191.9262.6185.2413.2195.0209.0284.8202.0382.8179.2192.5263.4185.8414.3195.6209.6285.6202.6383.9179.7193.1264.2186.4415.4196.2210.2286.3203.2385.0180.3193.7265.0187.0416.6196.8210.8287.1203.8386.2180.9194.3265.8187.6417.7197.4211.4287.9204.4387.3181.5194.9266.6188.2418.8198.0212.0288.7205.0388.4182.1195.5267.4188.8419.9198.5212.6289.5205.7389.5182.7196.1268.1189.4421.1199.1213.3290.3206.3390.7183.2196.7268.9190.0422.2199.7213.9291.1206.9391.8183.8197.3269.7190.6423.3200.3214.5291.9207.5392.9184.4197.9270.5191.2424.4200.9215.1292.7208.1394.0185.0198.5271.3191.8425.6201.5215.7293.5208.7395.2185.6199.2272.1192.4426.7202.1216.3294.3209.3396.3186.2199.8272.9193.0427.8202.7217.0295.0209.9397.4186.8200.4273.7193.6428.9203.3217.6295.8210.517 GB5009.7—2016表A.1(续)单位为毫克乳糖乳糖氧化亚铜葡萄糖果糖转化糖氧化亚铜葡萄糖果糖转化糖(含水)(含水)430.1203.9218.2296.6211.1460.5220.2235.1318.3227.9431.2204.5218.8297.4211.8461.6220.8235.8319.1228.5432.3205.1219.5298.2212.4462.7221.4236.4319.9229.1433.5205.1220.1299.0213.0463.8222.0237.1320.7229.7434.6206.3220.7299.8213.6465.0222.6237.7321.6230.4435.7206.9221.3300.6214.2466.1223.3238.4322.4231.0436.8207.5221.9301.4214.8467.2223.9239.0323.2231.7438.0208.1222.6302.2215.4468.4224.5239.7324.0232.3439.1208.7223.2303.0216.0469.5225.1240.3324.9232.9440.2209.3223.8303.8216.7470.6225.7241.0325.7233.6441.3209.9224.4304.6217.3471.7226.3241.6326.5234.2442.5210.5225.1305.4217.9472.9227.0242.2327.4234.8443.6211.1225.7306.2218.5474.0227.6242.9328.2235.5444.7211.7226.3307.0219.1475.1228.2243.6329.1236.1445.8212.3226.9307.8219.8476.2228.8244.3329.9236.8447.0212.9227.6308.6220.4477.4229.5244.9330.8237.5448.1213.5228.2309.4221.0478.5230.1245.6331.7238.1449.2214.1228.8310.2221.6479.6230.7246.3332.6238.8450.3214.7229.4311.0222.2480.7231.4247.0333.5239.5451.5215.3230.1311.8222.9481.9232.0247.8334.4240.2452.6215.9230.7312.6223.5483.0232.7248.5335.3240.8453.7216.5231.3313.4224.1484.1233.3249.2336.3241.5454.8217.1232.0314.2224.7485.2234.0250.0337.3242.3456.0217.8232.6315.0225.4486.4234.7250.8338.3243.0457.1218.4233.2315.9226.0487.5235.3251.6339.4243.8458.2219.0233.9316.7226.6488.6236.1252.7340.7244.7459.3219.6234.5317.5227.2489.7236.9253.7342.0245.818 GB5009.7—2016A.20.1mol/L铁氰化钾与还原糖含量对照表0.1mol/L铁氰化钾与还原糖含量对照表见表A.2。表A.20.1mol/L铁氰化钾与还原糖含量对照表0.1mol/L0.1mol/L0.1mol/L0.1mol/L还原糖还原糖还原糖还原糖铁氰化钾铁氰化钾铁氰化钾铁氰化钾%%%%mLmLmLmL0.100.052.301.164.502.376.703.790.200.102.401.214.602.446.803.850.300.152.501.264.702.516.903.920.400.202.601.304.802.577.003.980.500.252.701.354.902.647.104.060.600.312.801.405.002.707.204.120.700.362.901.455.102.767.304.180.800.413.001.515.202.827.404.250.900.463.101.565.302.887.504.311.000.513.201.615.402.957.604.381.100.563.301.665.503.027.704.451.200.603.401.715.603.087.804.511.300.653.501.765.703.157.904.581.400.713.601.825.803.228.004.651.500.763.701.885.903.288.104.721.600.803.801.956.003.348.204.781.700.853.902.016.103.418.304.851.800.904.002.076.203.478.404.921.900.964.102.136.303.538.504.992.001.014.202.186.403.608.605.052.101.064.302.256.503.678.705.122.201.114.402.316.603.738.805.19注:还原糖含量以麦芽糖计算。19'