商品粮食中还原糖和非还原糖含量的测定.doc

GB 551385本标准适用于商品粮食中还原糖和非还原糖含量的测定。其中铁氰化钾法主要适用于小麦粉。1还原糖测定1.1铁氰化钾法1.1.1仪器和用具1.1.1.1磨口带塞锥形瓶：100 ml；1.1.1.2量筒：50 ml、25 ml；1.1.1.3移液管：5 ml；1.1.1.4玻璃漏斗；1.1.1.5试管：直径1.82.0 cm，高约18 cm；1.1.1.6铝锅：作沸水浴用；1.1.1.7电炉：2000 W；1.1.1.8铁丝笼：放置试管用；1.1.1.9试管架；1.1.1.10锥形瓶：100 ml；1.1.1.11微量滴定管：5 ml或10 ml（刻度0.02 ml）；1.1.1.12分析天平：感量0.0001 g。1.1.2试剂1.1.2.195乙醇；1.1.2.2乙酸缓冲液：3 ml冰乙酸、6.8 g乙酸钠和比重1.84的硫酸4.5 ml，混合后用水稀释至1000 ml；1.1.2.312钨酸钠溶液：12 g钨酸钠Na2WO42H2O溶于100 ml水中；1.1.2.40.1 N铁氰化钾溶液：32.9 g干燥纯净的铁氰化钾与44.0 g碳酸钠溶于1000 ml水中；1.1.2.5乙酸盐溶液：70 g纯氯化钾和40 g硫酸锌溶于水中，再加入200 ml冰乙酸，再用水稀释至1000 ml，混匀；1.1.2.610碘化钾溶液：10 g纯碘化钾溶于100 ml水中，再加一滴饱和氢氧化钠溶液；1.1.2.71淀粉溶液：1 g可溶性淀粉，用少量水润湿调和后，倒入沸水100 ml，继续煮沸，搅拌直至溶液清晰；1.1.2.80.1 N硫代硫酸钠溶液（按GB 549085粮食、油料和植物油脂检验一般规则附录B进行配制和标定）。1.1.3操作方法1.1.3.1提取样品液：精确称取粉样5.675 g于100 ml磨口锥形瓶中，用5 ml乙醇浸湿全部试样，再加入50 ml乙酸缓冲液，摇匀后再加入2 ml钨酸钠溶液，在振荡器上混合振摇5 min，取出过滤，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。另取一锥形瓶不加试样，同上操作，滤液即为空白液。1.1.3.2氧化：精确吸取样品液5 ml于试管中，再精确加入5 ml铁氰化钾溶液，混合后立即将试管（置铁丝笼中，每次可同时作若干样品测定）放入剧烈沸腾的水浴中，并使管中液面在沸水液面下34 cm，加热准20 min后取出，立即用冷水迅速冷却。1.1.3.3滴定：将试管内容物倾入100 ml锥形瓶中，用25 ml乙酸盐溶液洗荡试管一并倾入锥形瓶，加5 ml 10碘化钾，混匀后，立即用0.1 N硫代硫酸钠滴定至淡黄色，再加1 ml淀粉溶液，继续滴定直至溶液蓝色消失，记下用去硫代硫酸钠溶液体积（V1）。1.1.3.4空白试验：吸取空白液5 ml，代替样品液同1.1.3.2和1.1.3.3操作，记下消耗的硫代硫酸钠溶液体积（V0）。1.1.4结果计算还原糖含量先按公式（1）计算出氧化样品液中“还原糖”所需0.1 N铁氰化钾溶液体积（V3），再根据此体积（ml）查表1，即可查得试样中含还原糖（以麦芽糖计算）的百分数。按公式（1）计算：（1）式中：V0滴定空白液消耗铁氰化钾溶液体积，ml；V1滴定样品液消耗铁氰化钾溶液体积，ml；V3氧化样品液中还原糖所需0.1 N铁氰化钾溶液体积，ml；N硫代硫酸钠溶液实际当量浓度。双试验结果允许差不超过0.05，求其平均数，即为检验结果。检验结果取小数点后第二位。1.1.50.1 N铁氰化钾（ml）与还原糖含量对照可查表1。注：还原糖含量以麦芽糖计算。1.2费林氏液法1.2.1仪器和用具1.2.1.1古氏坩埚：25 ml；1.2.1.2抽滤瓶：500 ml；1.2.1.3真空泵或水泵等。1.2.2试剂1.2.2.1费林氏溶液；a碱性酒石酸铜甲液：取硫酸铜结晶34.639 g，加适量水溶解，加硫酸0.5 ml，再加水至 500 ml，用精制石棉过滤；b碱性酒石酸铜乙液：取酒石酸钾钠173 g与氢氧化钠50 g，加适量水溶解，稀释至500 ml，用精制石棉过滤，贮存于具有橡皮塞的玻璃瓶内。1.2.2.2精制石棉：先用3 N盐酸将石棉浸泡23日后，用水洗净。再加10氢氧化钠溶液浸泡23日，倾去溶液，用热碱性酒石酸铜乙液浸泡数小时，用水洗净。再以3 N盐酸浸泡数小时，用水洗至不呈酸性，使之成为微细的软纤维，用水浸泡贮存于玻璃瓶内，作填充古氏坩埚用。1.2.2.30.1 N高锰酸钾标准溶液。1.2.2.41 N氢氧化钠溶液：取氢氧化钠4 g，加水溶解至100 ml。1.2.2.5硫酸铁溶液：取硫酸铁50 g，加水200 ml溶解后，慢慢加入硫酸100 ml，冷后加水至1000 ml。1.2.2.63 N盐酸：取盐酸25 ml，加水至100 ml。1.2.3操作方法表 10.1N K3/SFe(CN)6 ml还原糖0.100.200.300.400.500.600.700.800.901.001.101.201.301.401.501.601.701.801.902.002.102.202.302.402.502.602.702.802.903.003.103.203.303.403.503.603.703.803.904.004.104.204.304.404.504.604.704.804.905.005.105.205.305.405.505.605.705.805.906.006.106.206.306.406.506.606.706.806.907.007.107.207.307.407.507.607.707.807.908.008.108.208.308.408.508.608.708.800.050.100.150.200.250.310.360.410.460.510.560.600.650.710.760.800.850.900.961.011.061.111.161.211.261.301.351.401.451.511.561.611.661.711.761.821.881.952.012.072.132.182.252.312.372.442.512.572.642.702.762.822.882.953.023.083.153.223.283.343.413.473.533.603.673.733.793.853.923.984.064.124.184.254.314.384.454.514.584.654.724.784.854.924.995.055.125.191.2.3.1试样处理：准确称取试样1020 g放入250 ml容量瓶中，加水200 ml，在45水浴中加热1 h，并时时振摇，到时待冷后加水至刻度，静置后，吸取澄清液200 ml于另一250 ml容量瓶中，加碱性酒石酸铜甲液10 ml和1 N氢氧化钠溶液4 ml，摇匀，加水至刻度，静置30 min，用干燥滤纸过滤，弃去初滤液，其余滤液供测定还原糖和非还原糖用。1.2.3.2滴定：精密吸取制备的试样溶液50 ml于400 ml烧杯中，加入碱性酒石酸铜甲、乙液各25 ml，盖一表面皿，置电炉上加热，在4 min内沸腾，再煮沸2 min，趁热用铺有石棉的古氏坩埚（或垂融坩埚）抽滤，并用60热水洗涤烧杯和沉淀，至洗液不呈碱性为止。将古氏坩埚放回原400 ml烧杯中，加硫酸铁溶液25 ml和水25 ml，用玻棒搅拌，使氧化亚铜完全溶解，以0.1 N高锰酸钾标准溶液滴定至微红色。同时取水50 ml，加碱性酒石酸铜甲、乙液各25 ml，做试剂空白试验。1.2.4结果计算相当于试样中还原糖重量的氧化亚铜重量按公式（2）计算：x（VV0）N71.54（2）式中：x相当于试样中还原糖重量的氧化亚铜的重量，mg；V试样消耗高锰酸钾标准溶液的体积，ml；V0试样空白消耗高锰酸钾标准溶液的体积，ml；N高锰酸钾标准溶液的当量浓度；71.541 N高锰酸钾标准溶液1 ml相当于氧化亚铜的毫克数。由所得的氧化亚铜重量，按附录A的表查出相当的还原糖（以葡萄糖计）的重量。还原糖干基含量按公式（3）计算：（3）式中：A由附录A表中查得的还原糖（以葡萄糖计）的重量，mg；W试样重量，g；M试样水分百分率，；双试验结果允许差及小数点位数同1.1.4。注：煮沸时间必须控制在4 min内。可先取水50 ml加碱性酒石酸铜甲、乙液各25 ml，调节好适当的火力后，再作样品。煮沸后的溶液如不呈蓝色，表示糖量过高，可减少试样重量，另作。2非还原糖测定2.1铁氰化钾法所需仪器和用具同1.1.1。所需试剂同1.1.2。2.1.1操作方法分别吸取1.1.3.1样品液及空白液各5 ml于试管中，先在剧烈沸腾的水浴中加热15 min（样品液中非还原糖转化为还原糖），取出迅速冷却后，加入碱性铁氰化钾溶液5 ml，混匀后，再放入沸腾水浴中继续加热20 min，取出迅速冷却后，立即按1.1.3.3方法进行滴定，分别记下滴定样品液及空白液消耗硫代硫酸钠体积（）。2.1.2结果计算非还原糖含量先按公式（4）计算，求出氧化样品液中总“还原糖”所需0.1 N铁氰化钾溶液所需的体积（V4），然后减去单独氧化样品液中“还原糖”所需的铁氰化钾溶液体积（V3）公式（1），最后再根据V4V3的结果（ml）查表2，即可查得试样中含非还原糖（以蔗糖计）的百分数。（4）式中：滴定空白液消耗硫代硫酸钠溶液体积，ml；滴定样品液消耗硫代硫酸钠溶液体积，ml；V4氧化样品液中总还原糖所需0.1 N铁氰化钾溶液体积，ml；N硫代硫酸钠溶液当量浓度。双试验结果允许差不超过0.05，求其平均数，即为测定结果。测定结果取小数点后第二位。2.1.30.1 N铁氰化钾（ml）与非还原糖含量对照可查表2。注：非还原糖含量以蔗糖计算。表 20.1N K3Fe(CN)6/SUml非还原糖0.100.200.300.400.500.600.700.800.901.001.101.201.301.401.501.601.701.801.902.002.102.202.302.402.502.602.702.802.903.003.103.203.303.403.503.603.703.803.904.004.104.204.304.404.504.604.704.804.905.005.105.205.305.405.505.605.705.805.906.006.106.206.306.406.506.606.706.806.907.007.107.207.307.407.507.607.707.807.908.008.108.208.308.408.500.050.100.150.190.240.290.340.380.430.480.520.570.620.670.710.760.810.860.910.951.001.041.091.141.191.231.281.331.381.431.481.521.571.611.661.711.761.811.851.901.952.002.042.092.142.182.232.282.332.382.422.472.512.562.612.662.702.752.802.802.902.942.993.043.093.133.183.233.283.333.373.423.473.523.573.623.673.723.773.823.873.923.974.024.072.2费林氏液法2.2.1试剂2.2.1.16 N盐酸：取盐酸100 ml，加水至200 ml；2.2.1.2甲基红指示液：0.1甲基红乙醇溶液；2.2.1.320氢氧化钠溶液；2.2.1.4其余试剂同1.2.2。2.2.2操作方法吸取1.2.3.1项下已制备的样品液50 ml，注入1000 ml容量瓶中，加6 N盐酸5 ml，在6870水浴中加热15 min，冷却后加甲基红指示液2滴，用20氢氧化钠溶液中和，加水至刻度，混匀，然后按1.2.3.2测定样品液中总还原糖。2.2.3结果计算非还原糖干基含量（以蔗糖计）按公式（5）计算：（5）式中：A转化后测得的还原糖（以葡萄糖计）重量，mg；V转化后稀释至100 ml，用于测定还原糖的体积，ml；W原测定还原糖时试样重量，g；0.95还原糖（以葡萄糖计）换算为蔗糖的因数；M试样水分百分率，。双试验结果允许差及小数点位数同2.1.2。附录A相当于氧化亚铜重量的葡萄糖、果糖、转化糖重量表（补充件）相同于氧化亚铜重量的葡萄糖、果糖、转化糖重量见下表：mg氧化亚铜葡萄糖果 糖转化糖11.312.413.514.615.816.918.019.120.321.422.523.624.825.927.028.129.330.431.532.633.834.936.037.238.339.440.541.742.843.945.046.247.348.449.550.751.852.954.055.256.357.458.559.760.861.963.064.265.366.467.668.769.870.972.173.274.375.476.677.778.879.981.182.283.384.485.686.787.888.990.191.292.393.494.695.796.897.999.1100.2101.3102.5103.6104.7105.8107.0108.1109.2110.3111.5112.6113.7114.8116.0117.1118.2119.3120.5121.6122.7123.8125.0126.1127.2128.3129.5130.6131.7132.8134.0135.1136.2137.4138.5139.6140.7141.9143.0144.1145.2146.4147.5148.6149.7150.9152.0153.1154.2155.4156.5157.6158.7159.9161.0162.1163.2164.4165.5166.6167.8168.9170.0171.1172.3173.4174.5175.6176.8177.9179.0180.1181.3182.4183.5184.5185.8180.9188.0189.1190.3191.4192.5193.6194.8195.9197.0198.1199.3200.4201.5202.7203.8204.9206.0207.2208.3209.4210.5211.7212.8213.9215.0216.2217.3218.4219.5220.7221.8222.9224.0225.2226.3227.4228.5229.7230.8231.9233.1234.2235.3236.4237.6238.7239.8240.9242.1243.1244.3245.4246.6247.7248.8249.9251.1252.2253.3254.4255.6256.7257.8258.9260.1261.2262.3263.4264.6265.7266.8268.0269.1270.2271.3272.5273.6274.7275.8277.0278.1279.2280.3281.5282.6283.7284.8286.0287.1288.2289.3290.5291.6292.7293.8295.0296.1297.2298.3299.5300.6301.7302.9304.0305.1306.2307.4308.5309.6310.7311.9313.0314.1315.2316.4317.5318.6319.7320.9322.0323.1324.2325.4326.5327.6328.7329.9331.0332.1333.3334.4335.5336.6337.8338.9340.0341.1342.3343.4344.5345.6346.8347.9349.0350.1351.3352.4353.5354.6355.8356.9358.0359.1360.3361.4362.5363.6364.8365.9367.0368.2369.3370.4371.5372.7373.8374.9376.0377.2378.3379.4380.5381.7382.8383.9385.0386.2387.3388.4389.5390.7391.8392.9394.0395.2396.3397.4398.5399.7400.8401.9403.1404.2405.3406.4407.6408.7409.8410.9412.1413.2414.3415.4416.6417.7418.8419.9421.1422.2423.3424.4425.6426.7427.8428.9430.1431.2432.3433.5434.6435.7436.8438.0439.1440.2441.3442.5443.6444.7445.8447.0448.1449.2450.3451.5452.6453.7454.8456.0457.1458.2459.3460.5461.6462.7463.8465.0466.1467.2468.4469.5470.6471.7472.9474.0475.1476.2477.4478.5479.6480.7481.9483.0484.1485.2486.4487.5488.6489.74.65.15.66.06.57.07.58.08.58.99.49.910.410.911.411.912.312.813.313.814.314.815.315.716.216.717.217.718.218.719.219.720.120.621.121.622.122.623.123.624.124.625.125.626.126.527.027.528.028.529.029.530.030.531.031.532.032.533.033.534.034.535.035.536.036.537.037.538.038.539.039.540.040.541.041.542.042.543.043.544.044.545.045.546.046.547.047.548.048.549.049.550.050.651.151.652.152.653.153.654.154.655.155.656.156.757.257.758.258.759.259.760.260.761.361.862.362.863.363.864.364.965.465.966.466.967.468.068.569.069.570.070.571.171.672.172.673.173.774.274.775.275.776.376.877.377.878.378.979.479.981.481.081.582.082.583.183.684.184.685.285.786.286.787.387.888.388.989.489.990.491.091.592.092.693.193.694.294.795.295.796.396.897.397.998.498.999.5100.0100.5101.1101.6102.2102.7103.2103.8104.3104.8105.4105.9106.5107.0107.5108.1108.6109.2109.7110.2110.8111.3111.9112.4112.9113.5114.0114.6115.1115.7116.2116.7117.3117.8118.4118.9119.5120.0120.6121.1121.7122.2122.7123.3123.8124.4124.9125.5126.0126.6127.1127.7128.2128.8129.3129.9130.4131.0131.6132.1132.7133.2133.8134.3134.9135.4136.0136.5137.1137.7138.2138.8139.3139.9140.4141.0141.6142.1142.7143.2143.8144.4144.9145.5146.0146.6147.2147.7148.3148.8149.4150.0150.5151.1151.7152.2152.8153.4153.9154.5155.1155.6156.2156.8157.3157.9158.5159.0159.6160.2160.7161.3161.9162.5163.0163.6164.2164.7165.3165.9166.5167.0167.6168.2168.8169.3169.9170.5171.1171.6172.2172.8173.4173.9174.5175.1175.7176.3176.8177.4178.0178.6179.2179.7180.3180.2181.5182.1182.7183.2183.8184.4185.0185.6186.2186.8187.3187.9188.5189.1189.7190.3190.9191.5192.0192.6193.2193.8194.4195.0195.6196.2196.8197.4198.0198.5199.1199.7200.3200.9201.5202.1202.7203.3203.9204.5205.1205.7206.3206.9207.5208.1208.7209.3209.9210.5211.1211.7212.3212.9213.5214.1214.7251.3215.9216.5217.1217.8218.4219.0219.6220.2220.8221.4222.0222.6223.3223.9224.5225.1225.7226.3227.0227.6228.2228.8229.5230.1230.7231.4232.0232.7233.3234.0234.7235.3236.1236.95.15.66.16.77.27.78.38.89.39.910.410.911.512.012.513.113.614.214.715.215.816.316.817.417.918.419.019.520.120.621.121.722.222.823.323.824.424.925.426.026.527.127.628.228.729.229.830.330.931.431.932.533.033.634.134.735.235.836.336.837.437.938.539.039.640.140.741.241.742.342.843.443.944.545.045.646.146.747.247.848.348.949.450.050.551.151.652.252.753.353.854.454.955.556.056.657.157.758.258.859.359.960.461.061.662.162.763.263.864.364.965.466.066.567.167.768.268.869.369.970.471.071.672.172.773.273.874.374.975.576.076.677.177.778.378.879.480.080.581.181.682.282.883.383.984.485.085.686.186.787.387.888.489.089.590.190.691.291.892.392.993.594.094.695.295.796.396.997.498.098.699.299.7100.3100.9101.4102.0102.6103.1103.7104.3104.8105.4106.0106.6107.1107.1108.3108.8109.4110.0110.6111.1111.7112.3112.9113.4114.0114.6115.2115.7116.3116.9117.5118.0118.6119.2119.8120.3120.9121.5122.1122.6123.2123.8124.4125.0125.5126.1126.7127.3127.9128.4129.0129.6120.2130.8131.3131.9132.5133.1133.7134.2134.8135.4136.0136.6137.2137.7138.3138.9139.5140.1140.7141.3141.8142.4143.0143.6144.2144.8145.4145.9146.5147.1147.7148.3148.9149.5150.1150.6151.2151.8152.4153.0153.6154.2154.8155.4156.0156.5157.1157.7158.3158.9159.5160.1160.7161.3161.9162.5163.1163.7164.3164.9165.4166.0166.6167.2167.8168.4169.0169.6170.2170.8171.4172.0172.6173.2173.8174.4175.0175.6176.2176.8177.4178.0178.6179.2179.8180.4181.0181.6182.2182.8183.4184.0184.6185.2185.8186.4187.0187.6188.2188.8189.4190.1190.7191.3191.9192.5193.1193.7194.3194.9195.5196.1196.7197.3197.9198.5199.2199.8200.4201.0201.6202.2202.8203.4204.0204.7205.3205.9206.5207.1207.7208.3209.0209.6210.2210.8211.4212.0212.6213.3213.9214.5215.1215.7216.3217.0217.6218.2218.8219.5220.1220.7221.3221.9222.6223.2223.8224.4225.1225.7226.3226.9227.6228.2228.8229.4230.1230.7231.3232.0232.6233.2233.9234.5235.1235.8236.4237.1237.7238.4239.0239.7240.3241.0241.6242.2242.9243.6244.3244.9245.6246.3247.0247.8248.5249.2250.0250.8251.6252.7253.75.25.76.26.77.27.78.28.79.29.710.210.711.211.712.312.813.313.814.314.815.315.816.316.817.317.818.318.919.419.920.420.921.421.922.422.923.524.024.525.025.526.026.527.027.628.128.629.129.630.130.631.231.732.232.733.233.734.334.835.335.836.336.837.437.938.438.939.440.040.541.041.542.042.643.143.644.144.745.245.746.246.747.347.848.348.849.449.950.450.951.552.052.553.053.654.154.655.255.756.256.757.357.858.358.959.459.960.461.061.562.062.663.163.664.264.765.265.866.366.867.467.968.469.069.570.070.671.171.672.272.773.273.874.374.975.475.976.577.077.678.178.679.279.780.380.881.381.982.483.083.584.084.685.185.786.286.887.387.888.488.989.590.090.691.191.792.292.893.393.894.494.995.596.096.697.197.798.298.899