李繼榮，張?zhí)苽?，次仁德吉，楊小俊，次頓

糌粑加工過程中穩(wěn)定同位素指紋分餾效應(yīng)分析

李繼榮，張?zhí)苽?，次仁德吉，楊小俊，次頓

（西藏自治區(qū)農(nóng)牧科學(xué)院農(nóng)業(yè)質(zhì)量標(biāo)準(zhǔn)與檢測(cè)研究所/農(nóng)業(yè)農(nóng)村部農(nóng)產(chǎn)品質(zhì)量監(jiān)督檢驗(yàn)測(cè)試中心（拉薩），拉薩 850032）

【目的】系統(tǒng)分析青稞原料、炒制青稞和磨粉糌粑中穩(wěn)定碳、氮、氫和氧同位素的差異，揭示糌粑加工過程中青稞原料、炒制青稞和磨粉糌粑穩(wěn)定碳、氮、氫和氧同位素的組成特征及相關(guān)性，為青稞及其制品產(chǎn)地溯源提供理論與技術(shù)支撐?！痉椒ā?018年從西藏自治區(qū)日喀則市糌粑加工作坊分別采集炒制青稞和磨粉糌粑各11份，同時(shí)在對(duì)應(yīng)地點(diǎn)采集青稞原料11份；實(shí)驗(yàn)室模擬糌粑加工過程的青稞原料和炒制青稞各8份。利用元素分析-同位素比率質(zhì)譜儀（EA—IRMS）測(cè)定青稞原料、炒制青稞和糌粑中的穩(wěn)定碳、氮、氫、氧同位素。結(jié)合單因素方差分析及LSD或Games-Howell多重比較分析探究穩(wěn)定碳、氮、氫、氧同位素在青稞原料、炒制青稞和糌粑間的差異；逐步判別分析區(qū)分雅魯藏布江和年楚河青稞及其制品；獨(dú)立樣本T檢驗(yàn)分析水磨和電磨加工糌粑樣品穩(wěn)定碳、氮、氫、氧同位素差異；配對(duì)數(shù)據(jù)T檢驗(yàn)分析模擬試驗(yàn)中青稞原料、炒制青稞樣品穩(wěn)定碳、氮、氫、氧同位素差異，皮爾遜相關(guān)分析解析青稞原料和炒制青稞樣品穩(wěn)定碳、氮、氫、氧同位素的相關(guān)性。【結(jié)果】青稞原料、炒制青稞和糌粑間穩(wěn)定碳、氮、氫、氧同位素比值無顯著差異；穩(wěn)定氮同位素對(duì)不同流域來源青稞判別率為72.7%，穩(wěn)定氮、氧同位素對(duì)不同流域來源炒制青稞判別率為90.9%，糌粑判別率100%；水磨和電磨加工糌粑穩(wěn)定碳、氮、氫、氧同位素比值無顯著差異；模擬試驗(yàn)中青稞原料與炒制青稞穩(wěn)定碳、氮、氫、氧同位素比值無顯著差異，青稞原料與炒制青稞間穩(wěn)定碳、氮同位素存在顯著正相關(guān)（＜0.05）?！窘Y(jié)論】糌粑穩(wěn)定碳、氮、氧同位素與炒制青稞穩(wěn)定碳、氮、氧同位素間分餾效應(yīng)不顯著；青稞及其制品中穩(wěn)定同位素存在一定地域性；糌粑加工過程中使用電磨或水磨，對(duì)糌粑穩(wěn)定碳、氮、氫、氧同位素值無影響；青稞原料穩(wěn)定碳、氮同位素反映糌粑穩(wěn)定碳、氮同位素特征；利用穩(wěn)定同位素技術(shù)可以實(shí)現(xiàn)對(duì)糌粑的原產(chǎn)地溯源。

糌粑；青稞；穩(wěn)定同位素指紋；溯源性；分餾；西藏

0 引言

【研究意義】食品產(chǎn)地溯源技術(shù)是有效實(shí)施食品原產(chǎn)地追溯、保護(hù)名優(yōu)特產(chǎn)品的重要技術(shù)手段[1]。作為藏族人民最愛吃的食物之一，糌粑中含有豐富的營養(yǎng)物質(zhì)，具有熱量高、抗寒耐饑、降膽固醇、易于保存和制作的特點(diǎn)[2-4]。糌粑是由青稞經(jīng)除雜、清洗、晾干、翻炒、磨粉等工藝制成的粉狀食物[5]。傳統(tǒng)研磨方法除部分人力研磨外，大多是水磨碾磨，隨著電力資源的豐富，磨面機(jī)在糌粑加工過程中得到廣泛應(yīng)用[6]。黨君[7]的研究顯示拉薩市青稞脂肪酸含量高于青海、甘肅、云南地區(qū)的青稞，營養(yǎng)成分（水分、灰分、蛋白質(zhì)、脂肪、淀粉）表現(xiàn)為日喀則市優(yōu)于云南迪慶地區(qū)。穩(wěn)定同位素是用于植源性農(nóng)產(chǎn)品產(chǎn)地溯源的有效指標(biāo)[8-13]。研究糌粑加工過程中穩(wěn)定同位素的組成特征，有助于擴(kuò)大穩(wěn)定同位素指紋圖譜技術(shù)的應(yīng)用范圍，可為青稞產(chǎn)地溯源及青稞產(chǎn)業(yè)鏈追溯提供理論和技術(shù)支撐?！厩叭搜芯窟M(jìn)展】穩(wěn)定同位素指紋圖譜技術(shù)具有靈敏度高，實(shí)驗(yàn)操作簡(jiǎn)便，可較好地區(qū)分被追蹤物質(zhì)是新加入的還是試驗(yàn)系統(tǒng)固定的等優(yōu)點(diǎn)，已被廣泛應(yīng)用于農(nóng)產(chǎn)品產(chǎn)地溯源中[14]。該技術(shù)主要應(yīng)用于谷物[12,15-20]、果品[21-24]、茶葉[25-27]、經(jīng)濟(jì)作物[13,28]、蔬菜[11,29-31]等農(nóng)產(chǎn)品產(chǎn)地溯源。穩(wěn)定同位素指紋圖譜技術(shù)應(yīng)用于谷物產(chǎn)地溯源的研究對(duì)象多為小麥[12,19,32-34]和水稻[17,20,35-36]。常用的測(cè)定指標(biāo)有δ13C、δ15N、δD、δ18O、δ34S和86Sr/88Sr等[14]。LIU等[19]研究結(jié)果顯示，利用δ13C、δ15N、δD對(duì)新鄉(xiāng)、楊凌和石家莊冬小麥產(chǎn)地溯源的判別率為77.8%，結(jié)合δ13C、δ15N、δD和86Sr/88Sr的判別率達(dá)到98.1%。Wadood等[32]的研究結(jié)果表明小麥籽粒及其產(chǎn)品（面條、煮熟面條）間的δ13C、δ15N、δ18O無顯著差異，且δ13C、δ15N、δ18O可以用于對(duì)小麥籽粒及其產(chǎn)品（面條、煮熟面條）產(chǎn)地溯源。Fraser等[37]的碳化試驗(yàn)表明，低溫（230℃以下）加熱谷物對(duì)其δ13C影響不大，δ15N值平均富集1‰。【本研究切入點(diǎn)】糌粑加工過程中穩(wěn)定同位素是否存在分餾，進(jìn)而應(yīng)用于青稞及其制品產(chǎn)地溯源還不清楚，電磨或者水磨產(chǎn)糌粑穩(wěn)定同位素比值是否存在顯著差異也未見相關(guān)報(bào)道?！緮M解決的關(guān)鍵問題】研究不同成分、不同加工方式糌粑穩(wěn)定同位素差異，探究應(yīng)用穩(wěn)定同位素指紋圖譜技術(shù)進(jìn)行青稞及其制品產(chǎn)地溯源的可行性，為青稞及制品的產(chǎn)地溯源提供理論參考。

1 材料與方法

1.1 試驗(yàn)材料

2018年11月從西藏自治區(qū)日喀則市雅魯藏布江段和年楚河段糌粑加工作坊分別采集炒制青稞6份和5份，對(duì)應(yīng)磨粉糌粑6份和5份，同時(shí)在對(duì)應(yīng)地點(diǎn)采集青稞原料6份和5份，采樣點(diǎn)見表1；實(shí)驗(yàn)室模擬糌粑加工過程的青稞原料8份和炒制青稞8份。

表1 采樣點(diǎn)信息表

1.2 試驗(yàn)方法

1.2.1 樣品前處理 蒸餾水清洗青稞籽粒，除去表面附著物，青稞籽粒和炒青稞放入60℃烘箱內(nèi)48 h烘干至恒重，烘干后的樣品用藥用粉碎機(jī)粉碎，過200目篩；糌粑樣品放入60℃烘箱內(nèi)48 h烘干至恒重，過200目篩；處理好的樣品放入自封袋中備用。

1.2.2 糌粑模擬試驗(yàn) 稱取300 g青稞籽粒平均分成2份，每份150 g，一份樣品按照1.2.1所述進(jìn)行處理，直接用于δ13C、δ15N、δD和δ18O檢測(cè)；一份樣品進(jìn)行潤麥，添加超純水（Milli-Q，Millipore，USA），調(diào)整青稞含水量達(dá)到15%，潤麥時(shí)間3 h。不沾鍋中加入200 g蒸餾水清洗干凈自然晾干的沙子，放在電爐上加熱溫度至230—240℃[38]，倒入青稞籽粒迅速翻炒，待青稞爆腰率達(dá)85%以上時(shí)過60目篩分離青稞和沙子[6]。青稞原料和炒青稞按照1.2.1所述進(jìn)行處理。試驗(yàn)用沙子放入60℃烘箱內(nèi)48 h烘干至恒重，過200目篩進(jìn)行δ13C、δ15N、δD和δ18O檢測(cè)。

1.2.3 樣品測(cè)定 使用萬分之一天平稱取6.5 mg樣品放入錫箔杯中包樣進(jìn)行穩(wěn)定碳、氮同位素檢測(cè)，稱取1 mg樣品放入銀舟中包樣進(jìn)行穩(wěn)定氫、氧同位素檢測(cè)。元素分析儀（vario PYRO cube，Elementar，Germany）聯(lián)穩(wěn)定同位素質(zhì)譜儀（IsoPrime100，IsoPrime，UK）進(jìn)行穩(wěn)定碳、氮同位素檢測(cè)。元素分析儀（Flash EA2000型）聯(lián)穩(wěn)定同位素質(zhì)譜儀（MAT253型）進(jìn)行穩(wěn)定氫、氧同位素檢測(cè)。使用標(biāo)準(zhǔn)品為IAEA-600、IAEA-601、IAEA-CH-7，儀器對(duì)δ13C、δ15N、δ18O和δD的連續(xù)測(cè)定精度＜0.2‰。

穩(wěn)定同位素比值表示樣品與標(biāo)準(zhǔn)品之間偏差的千分?jǐn)?shù)：

δ（‰）=[(sample/standard)-1]×1000

式中：指13C或15N或18O或D；R=13C/12C或15N/14N或18O/16O或2H/1H；sample為被測(cè)樣品的同位素比值；standard為標(biāo)準(zhǔn)品的同位素比值。

1.3 數(shù)據(jù)處理及質(zhì)量控制

使用軟件Excel 2007對(duì)數(shù)據(jù)進(jìn)行整理，SPSS 20對(duì)數(shù)據(jù)進(jìn)行統(tǒng)計(jì)分析，使用單因素方差分析對(duì)糌粑生產(chǎn)過程中的青稞原料、炒制青稞和磨粉糌粑樣品的δ13C、δ15N、δD和δ18O值進(jìn)行分析。青稞樣品統(tǒng)計(jì)檢驗(yàn)前，用Kolmogorov-Smirnov和Levene統(tǒng)計(jì)量分別檢驗(yàn)所有數(shù)據(jù)的正態(tài)性和方差同質(zhì)性，滿足方差齊性時(shí)采用LSD多重比較，不滿足方差齊性時(shí)采用Games-Howell多重比較法進(jìn)行分析。使用逐步判別分析對(duì)雅魯藏布江和年楚河流域樣品進(jìn)行判別。使用獨(dú)立樣本T檢驗(yàn)對(duì)電磨和水磨研磨糌粑的穩(wěn)定同位素（δ13C、δ15N、δD和δ18O）進(jìn)行分析。使用配對(duì)數(shù)據(jù)T檢驗(yàn)對(duì)糌粑模擬試驗(yàn)中青稞原料和炒制青稞樣品中的穩(wěn)定同位素（δ13C、δ15N、δD和δ18O）進(jìn)行分析，使用Pearson相關(guān)分析青稞原料和糌粑中穩(wěn)定同位素（δ13C、δ15N、δD和δ18O）相關(guān)性。

2 結(jié)果

2.1 加工對(duì)糌粑穩(wěn)定同位素特征影響及差異

2.1.1 糌粑加工過程中穩(wěn)定同位素特征及差異 糌粑加工過程中青稞原料δ13C值介于-25.27‰—-23.89‰，炒青稞的δ13C介于-25.58‰—-24.27‰，糌粑的δ13C介于-25.60‰—-24.01‰；糌粑加工過程中青稞原料δ15N值介于0.55‰—4.69‰，炒青稞的δ15N值介于-0.38‰—6.74‰，糌粑的δ15N值介于1.02‰—6.90‰；糌粑加工過程中青稞原料δ18O值介于12.38‰—21.76‰，炒青稞的δ18O值介于10.63‰—21.79‰，糌粑的δ18O值介于12.81‰—23.28‰；糌粑加工過程中青稞原料δD值介于-206.76—-150.91‰，炒青稞的δD值介于-207.88‰—-160.45‰，糌粑的δD值介于-194.09‰—-159.40‰。如表2所示，δD值相對(duì)δ13C、δ15N和δ18O值標(biāo)準(zhǔn)差較大。

表2 糌粑加工過程中穩(wěn)定碳、氮、氧和氫同位素（平均數(shù)±標(biāo)準(zhǔn)差）

同一列不同小寫字母表示差異顯著（＜0.05）。下同

Different lowercase letters in the same column indicate significant differences (＜0.05). The same as below

單因素方差分析結(jié)果顯示（圖1、圖2），糌粑加工過程中青稞原料、炒青稞和糌粑間的穩(wěn)定碳、氮、氫和氧同位素間均無顯著差異，δ13C單因素方差分析結(jié)果為(2,30)=0.15（＞0.05），δ15N單因素方差分析結(jié)果為(2,30)=0.024（＞0.05），δ18O單因素方差分析結(jié)果為(2,30)=0.864（＞0.05），δD單因素方差分析結(jié)果為(2,30)=0.618（＞0.05）。

2.1.2 不同加工方式糌粑穩(wěn)定同位素差異 水磨和電磨加工糌粑δ13C、δ15N、δ18O、δD值如表2所示，水磨糌粑的δ13C值介于-25.27‰—-24.01‰，電磨糌粑的δ13C介于-24.86‰—-24.31‰；水磨糌粑的δ15N值介于1.98‰—6.90‰，電磨糌粑的δ15N值介于1.02‰—4.51‰；水磨糌粑的δ18O值介于15.41‰—23.28‰，電磨糌粑的δ18O值介于12.81‰—21.66‰；水磨糌粑的δD值介于-184.90—-159.40‰，電磨糌粑的δD值介于-194.09‰—-166.85‰。兩組加工方式間均無顯著差異。

表3 不同加工方式產(chǎn)糌粑樣品穩(wěn)定碳、氮、氧和氫同位素（平均數(shù)±標(biāo)準(zhǔn)差）

圖1 糌粑加工過程中穩(wěn)定碳、氮同位素

圖2 糌粑加工過程中穩(wěn)定氫、氧同位素

獨(dú)立樣本T檢驗(yàn)結(jié)果顯示（圖1、圖2），水磨糌粑穩(wěn)定碳、氮、氧和氫同位素比值與電磨糌粑穩(wěn)定碳、氮、氧和氫同位素比值無顯著差異，δ13C的9=-0.59（＞0.05），δ15N的9=1.0219（＞0.05），δ18O的9=0.56（＞0.05），δD的9=0.161（＞0.05）。

2.2 模擬加工對(duì)糌粑穩(wěn)定同位素特征影響及相關(guān)性

2.2.1 模擬糌粑加工過程青稞原料與炒青稞樣品穩(wěn)定同位素差異 模擬糌粑加工過程中青稞原料與炒青稞樣品δ13C、δ15N、δ18O、δD值如表4所示，配對(duì)數(shù)據(jù)的T檢驗(yàn)結(jié)果顯示（圖1、圖2），青稞原料δ13C、δ15N、δD、δ18O與炒青稞δ13C、δ15N、δD、δ18O值之間無顯著差異，值分別為7=0.27（＞0.05）、7=1.402（＞0.05）、7=0.175（＞0.05）和7=-0.94（＞0.05）。試驗(yàn)用沙子δ13C、δ18O、δD比值分別為21.438‰、-0.59‰、-169.21‰，δ15N比值未檢出。

表4 模擬糌粑加工過程中青稞原料與炒青稞樣品穩(wěn)定碳、氮、氧和氫同位素

2.2.2 模擬糌粑加工過程中青稞原料與炒青稞樣品穩(wěn)定同位素相關(guān)性分析 模擬糌粑加工試驗(yàn)得到的青稞原料和炒青稞之間的穩(wěn)定碳、氮、氧和氫同位素比值圖如圖3—6所示。Pearson相關(guān)分析結(jié)果顯示青稞原料δ13C、δ15N與炒青稞δ13C、δ15N存在顯著正相關(guān)，相關(guān)系數(shù)分別為=0.719（＜0.05）、=0.79（＜0.05）；青稞原料δD、δ18O與炒青稞δD、δ18O無顯著相關(guān)性，相關(guān)系數(shù)分別為=0.124（＞0.05）、=0.163（＞0.05）。

2.3 不同流域青稞及其制品產(chǎn)地溯源判別分析

雅魯藏布江和年楚河流域青稞及其制品逐步判別分析結(jié)果顯示，穩(wěn)定氮同位素比值可以作為不同流域青稞原料判別指標(biāo)，回代檢驗(yàn)判別率和交叉檢驗(yàn)判別率均為72.7%。穩(wěn)定氮同位素比值和穩(wěn)定氧同位素比值可以作為不同流域炒青稞和不同流域糌粑判別分析指標(biāo)。不同流域炒青稞回代檢驗(yàn)判別率和交叉檢驗(yàn)判別率均為90.9%，不同流域糌粑的回代檢驗(yàn)判別率和交叉檢驗(yàn)判別率均達(dá)到100%。如圖7所示，雅魯藏布江流域青稞及其制品穩(wěn)定同位素比值主要落在穩(wěn)定氮、氧同位素圖的左下方，而年楚河流域青稞及其制品穩(wěn)定同位素比值主要落在穩(wěn)定氮、氧同位素圖的右上方。雅魯藏布江流域青稞及其制品穩(wěn)定氮同位素較年楚河流域青稞及其制品穩(wěn)定氮同位素貧化；雅魯藏布江流域炒青稞和糌粑穩(wěn)定氧同位素較年楚河流域炒青稞和糌粑穩(wěn)定氧同位素貧化。

圖3 糌粑加工過程中穩(wěn)定碳同位素比值

圖4 糌粑加工過程中穩(wěn)定氮同位素比值

圖5 糌粑加工過程中穩(wěn)定氧同位素比值

圖6 糌粑加工過程中穩(wěn)定氘同位素比值

圖7 不同流域青稞及其制品穩(wěn)定氮、氧同位素比值

3 討論

近年來，基于穩(wěn)定同位素特征的谷物產(chǎn)地溯源技術(shù)已成為谷物地理標(biāo)志保護(hù)的重要手段。模擬青稞原料加工炒青稞的過程中，230—240℃加熱約2 min，青稞爆腰率便可達(dá)到85%，本研究中青稞原料與炒青稞間δ13C的結(jié)果與Fraser等[37]的碳化試驗(yàn)結(jié)果相同，氮δ15N結(jié)果相比Fraser等[37]得出的加熱使δ15N值平均富集1‰的結(jié)果有所不同，其原因可能與青稞加熱時(shí)間較短，美德拉反應(yīng)[39]未能導(dǎo)致青稞δ15N的變化有關(guān)。

炒青稞加工為糌粑的主要方式是研磨，炒青稞和糌粑間穩(wěn)定同位素?zé)o顯著差異，進(jìn)一步說明研磨處理對(duì)樣品δ13C、δ15N、δD、δ18O值無影響。電磨或水磨對(duì)糌粑δ13C、δ15N、δD、δ18O無影響，此結(jié)果與楊樂等[40]得出的直接剪碎或液氮研磨對(duì)羽毛的δ13C、δ15N值無影響的結(jié)果相似。調(diào)查結(jié)果顯示水磨相對(duì)電磨研磨的糌粑保質(zhì)期較長，但是對(duì)于一些小作坊來說，水磨相對(duì)電磨研磨存在一定的季節(jié)限制，當(dāng)冬季水流減小或無水時(shí)，水磨研磨糌粑則不可行。

判別分析結(jié)果顯示，青稞及其制品穩(wěn)定同位素存在一定的地域特征性。雅魯藏布江發(fā)源于西藏西南部喜馬拉雅山北麓的杰馬央宗冰川，是世界上海拔最高的一條大河，年楚河是雅魯藏布江的一級(jí)支流[41]。位于雅魯藏布江干流謝通門縣δD為-138.2‰，δ18O為-14.6‰；年楚河δD為-112.4‰，δ18O為-10.3‰[42]。李繼榮等[42]對(duì)2014年西藏主要水體穩(wěn)定氫、氧同位素研究結(jié)果顯示水體δD、δ18O的取值范圍分別為-152.06‰—-19.05‰、-16.96‰—4.66‰，青稞δD較水體δD偏貧化，青稞δ18O較水體δ18O偏富集，這一結(jié)果與LIU等[18]得出的脫脂小麥δD與0—20 cm土壤水δD呈正相關(guān)的結(jié)果不同，其原因可能是由于本試驗(yàn)中的青稞及其制品樣品為2018年采集，而水體δD、δ18O數(shù)據(jù)為2014年樣品，由于不同年際間氣候條件（溫度、濕度、降水量等）的不同，導(dǎo)致δD、δ18O比值不同[43]。但LIU等[18]的研究對(duì)象為低海拔地區(qū)冬小麥，屬于小麥屬植物，而本研究對(duì)象為高海拔青稞樣品，屬于大麥屬植物，不同屬、不同海拔植物δD、δ18O與土壤水δD、δ18O相關(guān)性是否一致需要做進(jìn)一步的研究。另外，由于本研究用于判別分析的樣本較少，尚需增加樣本量對(duì)判別分析結(jié)果做進(jìn)一步驗(yàn)證。

4 結(jié)論

青稞及其制品穩(wěn)定同位素存在一定的地域特征性；糌粑加工過程中使用電磨或水磨，對(duì)糌粑穩(wěn)定同位素δ13C、δ15N、δ18O、δD值無顯著影響；模擬糌粑加工的炒青稞與青稞原料穩(wěn)定同位素指紋無顯著差異。穩(wěn)定同位素指紋分析技術(shù)可以應(yīng)用到青稞及其產(chǎn)品產(chǎn)地溯源中。

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Fractionation Effect of Stable Isotopic Ratios in Tsamba Processing

LI JiRong, ZHANG TangWei, CIREN DeJi, YANG XiaoJun, CI Dun

(Institute of Agricultural Product Quality Standard and Testing Research, Tibet Academy of Agricultural and Animal Husbandry Sciences/Supervision and Testing Center for Farm Products Quality, Ministry of Agriculture and Rural Affairs, Lhasa 850032)

【Objective】Our study mainly analyzed the difference of stable carbon, nitrogen, hydrogen, and oxygen isotopes, and revealed the characteristics and correlations of stable carbon, nitrogen, hydrogen, and oxygen isotopes in raw highland barley material, highland barley stir-frying, and milling tsamba in tsamba processing, which could provide a theoretical and technical basis for geographical origin traceability of highland barley and its products. 【Method】 We collected 11 samples of both stir-frying highland barley and milling tsamba from Xigaze (Tibet) tsamba processing workshop in 2018, and 11 samples of raw highland barley material were collected simultaneously from corresponding sites; 8 samples of both raw highland barley material and stir-frying highland barley were collected by the simulation of tsamba processing in the laboratory. Stable carbon, nitrogen, hydrogen, and oxygen isotopes were measured by element analysis-isotope ratio mass spectrometer (EA-IRMS). The one-way analysis of variance was combined with LSD or Games-Howell multiple comparison analysis to analyze the difference of stable carbon, nitrogen, hydrogen, and oxygen isotopes from perspectives of raw highland barley material, stir-frying highland barley, and tsamba. Stepwise discriminant analysis was employed to distinguish highland barley and its products from Yarlung Tsangpo River and Nianchu River. We used independent - sample T test to discover the difference of stable carbon, nitrogen, hydrogen, and oxygen isotopic between water milling tsamba and electric grinding tsamba. Paired T test was adopted to analyze the difference of stable carbon, nitrogen, hydrogen, and oxygen isotopes in raw highland barley material and stir-frying highland barley samples in the simulation experiment. And Pearson correlation analysis was used to analyze the correlation of stable carbon, nitrogen, hydrogen, and oxygen isotopes in raw highland barley material and stir-frying highland barley. 【Result】 No significant difference was found in stable carbon, nitrogen, hydrogen, and oxygen isotope ratios among raw highland barley material, stir-frying highland barley, and tsamba. The highland barley discrimination rate of stable nitrogen isotope from different watersheds was 72.7%, and the stir-frying highland barley discriminant rate of stable nitrogen and oxygen isotopes from different watersheds was 90.9%, whereas the tsamba discriminant rate was 100%. No significant difference was found in stable carbon, nitrogen, hydrogen, and oxygen isotope ratios between water milling tsamba and electric grinding tsamba. In the simulation experiment, there was no difference in stable carbon, nitrogen, hydrogen, and oxygen isotope ratios between raw highland barley material and stir-frying highland barley, while significant positive correlation was found in stable carbon and nitrogen isotope ratios between raw highland barley materials and stir-frying highland barley (＜0.05). 【Conclusion】 The fractionation effect of the stable carbon, nitrogen, and oxygen isotopes between stir-frying highland barley and tsamba was not significant. The stable isotopes in highland barley and its products were regional. In the tsamba processing, the use of either electric grinding or water milling had no effect on the stable carbon, nitrogen, hydrogen, and oxygen isotope ratios of tsamba. Simulation of tsamba processing experiment results showed that stable carbon and nitrogen isotopes in raw highland barley material could reflect the stable isotopes characteristics of those in tsamba. Therefore, stable isotope technology could be used for realizing the geographical origin traceability of tsamba．

tsamba; highland barley; stable isotope fingerprint; traceability; fractionation; Tibet

2019-06-03；

2019-08-23

西藏自治區(qū)科技重大專項(xiàng)（Z2016B01N04，ZD20170014，XZ201801NA04，XZ201901NA04）、國家大麥青稞產(chǎn)業(yè)體系（CARS-05-02-06）

李繼榮，Tel：18089980869；E-mail：ljr18697179656@163.com。通信作者次頓，Tel：13989086593；Fax：0891-6868491；E-mail：13989086593@163.com。通信作者張?zhí)苽?，Tel：13518997809；Fax：0891-6868491；E-mail：zhangtangwei04@163.com

（責(zé)任編輯 趙伶俐）