GB 8305—87中華人民共和國商業部1987—1l-19批準 1988-07-01實施本標準適用于茶葉中水浸出物的測定。本標準等效采用國際標準ISO 1574—1980《茶一(yi)水(shui)(shui)(shui)浸(jin)出(chu)物(wu)(wu)(wu)(wu)測(ce)定(ding)(ding)(ding)》。水(shui)(shui)(shui)浸(jin)出(chu)物(wu)(wu)(wu)(wu)是(shi)(shi)指(zhi)在規(gui)定(ding)(ding)(ding)的(de)(de)(de)(de)條件下(xia),用(yong)沸(fei)(fei)(fei)(fei)水(shui)(shui)(shui)萃取(qu)茶(cha)葉(xie)(xie)(xie)中(zhong)(zhong)的(de)(de)(de)(de)可溶性(xing)物(wu)(wu)(wu)(wu)質(zhi)。1 原理(li)用(yong)沸(fei)(fei)(fei)(fei)水(shui)(shui)(shui)萃取(qu)茶(cha)葉(xie)(xie)(xie)中(zhong)(zhong)的(de)(de)(de)(de)可溶性(xing)物(wu)(wu)(wu)(wu)質(zhi),再經過(guo)濾(lv)(lv)(lv)、蒸(zheng)發(fa)(fa)至(zhi)(zhi)(zhi)干,稱(cheng)量(liang)(liang)(liang)殘(can)留物(wu)(wu)(wu)(wu)。2 儀(yi)器(qi)(qi)(qi)(qi)和用(yong)具實驗室常(chang)規(gui)儀(yi)器(qi)(qi)(qi)(qi)及下(xia)列(lie)各項(xiang):2.1鼓風電熱恒(heng)(heng)溫干燥(zao)(zao)箱(xiang):溫控103±2℃。2.2恒(heng)(heng)溫水(shui)(shui)(shui)浴(yu)。2.3具蓋蒸(zheng)發(fa)(fa)皿:直徑60mm,高50mm,容(rong)量(liang)(liang)(liang)80ml。2.4干燥(zao)(zao)器(qi)(qi)(qi)(qi),內盛有效(xiao)干燥(zao)(zao)劑。2.5分(fen)(fen)析天平:感(gan)量(liang)(liang)(liang)0.001g。2.6容(rong)量(liang)(liang)(liang)瓶:500ml。2.7錐形瓶:500ml。3 操(cao)作方法(fa)3.1 取(qu)樣(yang)(yang)(yang)按(an)照GB 8302—87《茶(cha) 取(qu)樣(yang)(yang)(yang)》的(de)(de)(de)(de)規(gui)定(ding)(ding)(ding)取(qu)樣(yang)(yang)(yang)。3.2 試(shi)(shi)樣(yang)(yang)(yang)制備(bei)按(an)照GB 8303—87《茶(cha) 磨碎(sui)試(shi)(shi)樣(yang)(yang)(yang)的(de)(de)(de)(de)制備(bei)及其干物(wu)(wu)(wu)(wu)質(zhi)含量(liang)(liang)(liang)測(ce)定(ding)(ding)(ding)》的(de)(de)(de)(de)規(gui)定(ding)(ding)(ding),制備(bei)試(shi)(shi)樣(yang)(yang)(yang)。3.3 蒸(zheng)發(fa)(fa)皿的(de)(de)(de)(de)準(zhun)(zhun)備(bei)將具蓋蒸(zheng)發(fa)(fa)皿(2.3)置于103±2℃的(de)(de)(de)(de)恒(heng)(heng)溫干燥(zao)(zao)箱(xiang)(2.1)內,烘(hong)干1h,取(qu)出(chu),在干燥(zao)(zao)器(qi)(qi)(qi)(qi)內(2.4)冷(leng)卻(que)(que)至(zhi)(zhi)(zhi)室溫,稱(cheng)量(liang)(liang)(liang)(精確(que)至(zhi)(zhi)(zhi)0.001g)。3.4 測(ce)定(ding)(ding)(ding)步驟3.4.1 試(shi)(shi)液(ye)的(de)(de)(de)(de)制備(bei)稱(cheng)取(qu)3g(準(zhun)(zhun)確(que)至(zhi)(zhi)(zhi)0.001g)磨碎(sui)試(shi)(shi)樣(yang)(yang)(yang)(3.2)于500ml錐形瓶(2.7)中(zhong)(zhong),加(jia)沸(fei)(fei)(fei)(fei)蒸(zheng)餾(liu)水(shui)(shui)(shui)450ml,立(li)即移(yi)入沸(fei)(fei)(fei)(fei)水(shui)(shui)(shui)浴(yu)(2.2)中(zhong)(zhong),浸(jin)提45min①(每隔(ge)l0min搖動一(yi)次(ci))。浸(jin)提完畢后(hou)立(li)即趁熱減壓過(guo)濾(lv)(lv)(lv)②。濾(lv)(lv)(lv)液(ye)移(yi)入500ml容(rong)量(liang)(liang)(liang)瓶(2.6)中(zhong)(zhong),殘(can)渣用(yong)少(shao)量(liang)(liang)(liang)熱蒸(zheng)餾(liu)水(shui)(shui)(shui)洗(xi)滌2~3次(ci),并將濾(lv)(lv)(lv)液(ye)濾(lv)(lv)(lv)入上述(shu)容(rong)量(liang)(liang)(liang)瓶中(zhong)(zhong),冷(leng)卻(que)(que)后(hou)用(yong)蒸(zheng)餾(liu)水(shui)(shui)(shui)稀(xi)釋至(zhi)(zhi)(zhi)刻(ke)度。3.4.2 測(ce)定(ding)(ding)(ding)準(zhun)(zhun)確(que)吸取(qu)上述(shu)試(shi)(shi)液(ye)(3.4.1)50ml,注入已知質(zhi)量(liang)(liang)(liang)的(de)(de)(de)(de)具蓋蒸(zheng)發(fa)(fa)皿(3.3)中(zhong)(zhong),在沸(fei)(fei)(fei)(fei)水(shui)(shui)(shui)浴(yu) (2.2)上小(xiao)(xiao)心蒸(zheng)干,然后(hou)移(yi)入103±2℃的(de)(de)(de)(de)恒(heng)(heng)溫干燥(zao)(zao)箱(xiang)(2.1)內烘(hong)3h③。取(qu)出(chu)加(jia)蓋,立(li)即移(yi)入干燥(zao)(zao)器(qi)(qi)(qi)(qi)(2.4)內冷(leng)卻(que)(que)至(zhi)(zhi)(zhi)室溫,稱(cheng)量(liang)(liang)(liang),再烘(hong)1h。在干燥(zao)(zao)器(qi)(qi)(qi)(qi)內冷(leng)卻(que)(que)至(zhi)(zhi)(zhi)室溫,稱(cheng)量(liang)(liang)(liang),重復此操(cao)作,直至(zhi)(zhi)(zhi)相繼兩次(ci)稱(cheng)量(liang)(liang)(liang)差不超過(guo)0.001g。以(yi)最小(xiao)(xiao)稱(cheng)量(liang)(liang)(liang)為準(zhun)(zhun)。4 結果(guo)計(ji)算4.1 計(ji)算方法(fa)和公式茶(cha)葉(xie)(xie)(xie)中(zhong)(zhong)水(shui)(shui)(shui)浸(jin)出(chu)物(wu)(wu)(wu)(wu),以(yi)干態質(zhi)量(liang)(liang)(liang)百分(fen)(fen)率表示,按(an)下(xia)式計(ji)算:如果(guo)符合重復性(xing)(4.2)的(de)(de)(de)(de)要(yao)求,取(qu)兩次(ci)測(ce)定(ding)(ding)(ding)的(de)(de)(de)(de)算術(shu)平均值作為結果(guo)。4.2 重復性(xing)同(tong)一(yi)樣(yang)(yang)(yang)品(pin)的(de)(de)(de)(de)兩次(ci)測(ce)定(ding)(ding)(ding)值之差,每100g試(shi)(shi)樣(yang)(yang)(yang)不得超過(guo)0.5g。5 結果(guo)報告試(shi)(shi)驗報告應(ying)包括(kuo)下(xia)列(lie)內容(rong):a.使用(yong)的(de)(de)(de)(de)方法(fa);b.測(ce)定(ding)(ding)(ding)的(de)(de)(de)(de)結果(guo)(取(qu)小(xiao)(xiao)數點后(hou)一(yi)位(wei));c.本(ben)(ben)(ben)(ben)標(biao)(biao)準(zhun)(zhun)中(zhong)(zhong)未規(gui)定(ding)(ding)(ding)的(de)(de)(de)(de)或另加(jia)的(de)(de)(de)(de)操(cao)作;d.試(shi)(shi)樣(yang)(yang)(yang)的(de)(de)(de)(de)名(ming)稱(cheng)和產地;e.試(shi)(shi)驗日期,操(cao)作人員(yuan)。附加(jia)說(shuo)明(ming):本(ben)(ben)(ben)(ben)標(biao)(biao)準(zhun)(zhun)由全國(guo)(guo)食品(pin)工(gong)業標(biao)(biao)準(zhun)(zhun)化(hua)技術(shu)委員(yuan)會提出(chu)。本(ben)(ben)(ben)(ben)標(biao)(biao)準(zhun)(zhun)由中(zhong)(zhong)國(guo)(guo)農業科(ke)學院茶(cha)葉(xie)(xie)(xie)研究所、商業部(bu)杭州(zhou)茶(cha)葉(xie)(xie)(xie)加(jia)工(gong)研究所、上海進出(chu)口商品(pin)檢(jian)驗局負責(ze)起(qi)草。本(ben)(ben)(ben)(ben)標(biao)(biao)準(zhun)(zhun)主要(yao)起(qi)草人劉維華(hua)、鐘(zhong)蘿、嚴(yan)家(jia)輝、李名(ming)君、郭(guo)雯飛、王濟安。① 國(guo)(guo)際(ji)標(biao)(biao)準(zhun)(zhun)ISO 1574-80中(zhong)(zhong)是(shi)(shi)加(jia)水(shui)(shui)(shui)后(hou)回流(liu)抽提1h,現改(gai)為沸(fei)(fei)(fei)(fei)水(shui)(shui)(shui)浴(yu)浸(jin)提45min。② 國(guo)(guo)際(ji)標(biao)(biao)準(zhun)(zhun)ISO 1574—80中(zhong)(zhong)是(shi)(shi)常(chang)壓過(guo)濾(lv)(lv)(lv),本(ben)(ben)(ben)(ben)標(biao)(biao)準(zhun)(zhun)采用(yong)減壓過(guo)濾(lv)(lv)(lv)。③ 國(guo)(guo)際(ji)標(biao)(biao)準(zhun)(zhun)ISO 1574--80中(zhong)(zhong)烘(hong)2h,本(ben)(ben)(ben)(ben)標(biao)(biao)準(zhun)(zhun)烘(hong)3h。標(biao)(biao)準(zhun)(zhun)號:GB 8305—87
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