殺菌方式對(duì)即食胡蘿卜片揮發(fā)性風(fēng)味物質(zhì)的影響

米瑞芳，劉俊梅，胡小松，吳繼紅

（中國(guó)農(nóng)業(yè)大學(xué)食品科學(xué)與營(yíng)養(yǎng)工程學(xué)院，國(guó)家果蔬加工工程技術(shù)研究中心，農(nóng)業(yè)部果蔬加工重點(diǎn)開(kāi)放實(shí)驗(yàn)室，北京 100083）

殺菌方式對(duì)即食胡蘿卜片揮發(fā)性風(fēng)味物質(zhì)的影響

米瑞芳，劉俊梅，胡小松，吳繼紅※

（中國(guó)農(nóng)業(yè)大學(xué)食品科學(xué)與營(yíng)養(yǎng)工程學(xué)院，國(guó)家果蔬加工工程技術(shù)研究中心，農(nóng)業(yè)部果蔬加工重點(diǎn)開(kāi)放實(shí)驗(yàn)室，北京 100083）

為研究不同殺菌方式對(duì)即食胡蘿卜片揮發(fā)性風(fēng)味物質(zhì)的影響，運(yùn)用固相微萃取和氣相色譜-質(zhì)譜聯(lián)用技術(shù)，分別對(duì)新鮮胡蘿卜片和經(jīng)巴氏殺菌、超高壓殺菌、熱輔助超高壓殺菌處理的即食胡蘿卜片及其貯藏期間（4℃，60 d）的揮發(fā)性組分進(jìn)行對(duì)比分析。試驗(yàn)結(jié)果表明：新鮮胡蘿卜片的主要芳香成分為萜烯類物質(zhì)。與未殺菌組相比，經(jīng)不同殺菌處理后，即食胡蘿卜片的萜烯類物質(zhì)含量均有所降低，其中巴氏殺菌組降低的最多。在貯藏前期（20～30 d），超高壓處理即食胡蘿卜片的萜烯類物質(zhì)的含量最高，超高壓殺菌在短期內(nèi)較好地保持了胡蘿卜特有的香氣，即食胡蘿卜片品質(zhì)較好；其次是熱輔助壓力殺菌組，熱輔助壓力殺菌組即食胡蘿卜片的β-蒎烯、β-石竹烯的含量較其他處理組較高，較好地保持了胡蘿卜的松樹(shù)樹(shù)脂香氣以及辛香氣味；而巴氏殺菌組即食胡蘿卜片的萜烯類物質(zhì)含量最低，即食胡蘿卜片的品質(zhì)相對(duì)較差。研究結(jié)果可為新型殺菌技術(shù)在即食產(chǎn)品領(lǐng)域的應(yīng)用提供參考。

殺菌；貯藏；風(fēng)味；即食胡蘿卜片；超高壓技術(shù)；熱輔助壓力殺菌技術(shù)；巴氏殺菌技術(shù)

0 引言

隨著生活水平的提高，人們對(duì)食品質(zhì)量的要求不再僅僅局限于安全衛(wèi)生，對(duì)食品的色、香、味、營(yíng)養(yǎng)成分等也提出了更高的要求。由于傳統(tǒng)的熱殺菌技術(shù)使食品失去了其原有的新鮮度和風(fēng)味，營(yíng)養(yǎng)價(jià)值明顯降低，于是推動(dòng)了新型殺菌技術(shù)—超高壓殺菌（high hydrostatic pressure，HHP）的發(fā)展。經(jīng)超高壓處理的食品能較好地保持其原有的色澤、香氣、維生素等營(yíng)養(yǎng)成分，符合現(xiàn)代食品“營(yíng)養(yǎng)、健康、安全”的發(fā)展理念[1]。超高壓還可和熱處理結(jié)合即熱輔助超高壓殺菌技術(shù)（pressure-assisted thermal sterilization，PATS），能夠在較低的殺菌溫度下，保證食品中的營(yíng)養(yǎng)成分不被破壞的同時(shí)，殺滅食品中的耐壓菌以及低酸食品中的單增李斯特菌、肉毒桿菌及其毒素，可以有效地增加對(duì)芽孢的殺滅效果[2-4]，從而使食品達(dá)到商業(yè)無(wú)菌的狀態(tài)。同時(shí)PATS殺菌技術(shù)不會(huì)產(chǎn)生由高溫而導(dǎo)致的蒸煮味；從而使食品較好地保留其原有的風(fēng)味。目前PATS已通過(guò)了美國(guó)國(guó)家食品安全與技術(shù)中心和美國(guó)DUST（Dual Use Science and Technology）聯(lián)盟成員嚴(yán)格的驗(yàn)證程序和安全評(píng)估，其加工的食品已經(jīng)在伊拉克和阿富汗等戰(zhàn)場(chǎng)上應(yīng)用[5]。國(guó)內(nèi)對(duì)該技術(shù)的工業(yè)化應(yīng)用尚處于空白。

胡蘿卜因含有豐富的營(yíng)養(yǎng)物質(zhì)以及低廉的價(jià)格和特有的風(fēng)味，而廣受消費(fèi)者青睞[6]。因此可通過(guò)開(kāi)發(fā)即食胡蘿卜片產(chǎn)品，來(lái)方便人們快節(jié)奏的生活，使人們從廚房中解放出來(lái)。近年來(lái)，對(duì)胡蘿卜香氣成分的研究已有報(bào)道。Kjeldsen F等[7]研究了胡蘿卜在凍藏和冷藏期間的香氣成分變化；陳瑞娟等[8]研究了干燥方式對(duì)胡蘿卜超微粉中揮發(fā)性風(fēng)味物質(zhì)的影響；徐麗娜[9]研究了超高壓處理對(duì)胡蘿卜汁香氣成分的影響。而關(guān)于熱輔助壓力殺菌對(duì)即食胡蘿卜片風(fēng)味物質(zhì)的影響研究尚未見(jiàn)報(bào)道。

本研究以即食胡蘿卜片為研究對(duì)象，基于固相微萃取-氣質(zhì)聯(lián)用（solid-phase microextraction-gas chromatographymass spectrometry，SPME-GC-MS）技術(shù)[10]，通過(guò)將PATS殺菌、HHP殺菌與傳統(tǒng)熱殺菌前后產(chǎn)品的揮發(fā)性風(fēng)味成分的變化進(jìn)行比較分析，以期為新型食品殺菌技術(shù)（PATS、HHP）在即食產(chǎn)品領(lǐng)域的應(yīng)用提供理論依據(jù)。

1 材料與方法

1.1 材料與試劑

胡蘿卜，選購(gòu)于中國(guó)農(nóng)業(yè)大學(xué)家屬區(qū)菜市場(chǎng)，品種為紅芯三號(hào)，外觀整齊，脆甜可口，可作鮮食與加工用。

丙酮、乙醇（色譜純）、(R)-(+)-檸檬烯（>99%）、C5-C20烷烴系列標(biāo)準(zhǔn)樣品溶液，美國(guó)Sigma-Aldrich公司；NaCl（分析純）、萜品油烯、萜品烯、β-蒎烯（>95%）、β-石竹烯（>90%），北京信易達(dá)金生物科技有限公司；氦氣（>99.999%），北京千禧京城氣體有限公司。

1.2 儀器與設(shè)備

HHP-650超高壓設(shè)備，包頭科發(fā)新型高技術(shù)食品機(jī)械有限責(zé)任公司；HH.S11-4恒溫水浴鍋，北京長(zhǎng)安科學(xué)儀器廠；CAR/PDMS/DVB萃取頭、HP-5MS毛細(xì)管色譜柱（30 m×0.25 mm×0.25 μm）、Agilent7890A-5975C氣相色譜-質(zhì)譜聯(lián)用儀，美國(guó)安捷倫公司；EY-300A分析天平，日本松下電器公司。

1.3 方 法

1.3.1 預(yù)處理

胡蘿卜的預(yù)處理參照徐麗娜[9]的研究，經(jīng)挑選、清洗、去皮、50 mg/L的二氧化氯消毒5 min后，切成3～4 mm的薄片，利用L-抗壞血酸溶液（0.05%～0.10%）護(hù)色5 min，并用開(kāi)水燙漂15 s，快速冷卻、瀝干、透明蒸煮袋分裝后進(jìn)行真空包裝。

1.3.2 殺菌處理

真空包裝即食胡蘿卜片的殺菌處理參照Biniam T等[11]的研究，分別采用巴氏殺菌（90℃，30 min）、HHP殺菌（550 MPa，25℃，10 min）和PATS殺菌（500 MPa，50℃，10 min）處理后，于4℃冷庫(kù)中貯藏60 d，其中未殺菌處理的即食胡蘿卜片作為對(duì)照組，定期進(jìn)行風(fēng)味分析。

1.3.3 SPME條件

即食胡蘿卜片揮發(fā)性成分的提取參照Vervoort L等[12]的報(bào)道，并略作修改。按照貨架期試驗(yàn)設(shè)計(jì)，將即食胡蘿卜片從冷庫(kù)取出，打漿至泥狀。精確稱取8.5 g胡蘿卜泥放入頂空瓶中，加入15 mL飽和NaCl溶液，置于40℃恒溫水浴鍋中預(yù)熱平衡20 min。將經(jīng)老化的SPME萃取針插入頂空瓶，于40℃萃取20 min后，手動(dòng)進(jìn)樣至GC-MS中，250℃解析5 min。

1.3.4 GC-MS分析

色譜條件：色譜柱為HP-5毛細(xì)管柱（30 m×250 μm× 0.25 μm）；進(jìn)樣口溫度250℃；升溫程序：參照Vervoort L等[12]的報(bào)道，并略作修改。起始溫度40℃，保持1 min，以4℃/min升至172℃，再以30℃/min升至260℃，保持5 min；載氣為高純氦氣，流速1.0 mL/min；不分流進(jìn)樣。

質(zhì)譜條件：電子轟擊（electron impact，EI）離子源，電子能量為70 eV；離子源溫度230℃；四級(jí)桿溫度150℃；質(zhì)量掃描范圍：35～400 amu，采用全掃描模式采集信號(hào)。

1.3.5 即食胡蘿卜片揮發(fā)性成分定性定量分析

數(shù)據(jù)分析采用NIST 08.L標(biāo)準(zhǔn)譜庫(kù)檢索，利用系列正構(gòu)烷烴測(cè)定各組分RI值，結(jié)合保留指數(shù)及相關(guān)文獻(xiàn)進(jìn)行定性分析[13]。采用面積歸一化法和外標(biāo)法進(jìn)行定量分析[14]。定量數(shù)據(jù)采用Origin8.1Pro進(jìn)行統(tǒng)計(jì)分析并制圖。

2 結(jié)果與分析

2.1 不同殺菌方式對(duì)即食胡蘿卜片中揮發(fā)性成分的分析

利用HS-SPME-GC-MS對(duì)3種殺菌方式處理的即食胡蘿卜片和未殺菌即食胡蘿卜片（對(duì)照組）在貯藏期主要揮發(fā)性組分的定性與面積歸一化分析結(jié)果如表1所示。由表1可以看出，未殺菌即食胡蘿卜的揮發(fā)性成分有萜烯化合物、酯類、醛類、醇類、酮類等，主要以萜烯類化合物為主，占胡蘿卜總揮發(fā)性成分的40%以上。檢測(cè)出萜烯類物質(zhì)主要有(1R)-(+)-α蒎烯（松樹(shù)樹(shù)脂香氣）、β-蒎烯（松樹(shù)樹(shù)脂香氣）、莰烯、月桂烯（清淡的香脂氣味）、右旋萜二烯、萜品烯（柑橘和檸檬香氣）、萜品油烯、β-石竹烯（木香、柑橘香以及溫和的丁香氣味）等[15]，其中β-石竹烯所占的比例較大，這與Kjeldsen F[7]、陳瑞娟[8]和Alasalvar C[16]的研究結(jié)果一致。醛類物質(zhì)主要有β-環(huán)檸檬醛（似紫羅蘭酮的香氣），還有少量的正庚醛、正辛醛。酮類物質(zhì)主要有甲基庚烯酮（新鮮的青香和柑橘樣氣息）；醇類物質(zhì)較少；另外還檢測(cè)到少量的芳香烴類。上述這些揮發(fā)性成分所呈現(xiàn)出的香氣共同構(gòu)成了即食胡蘿卜片特有的香味。

圖1 貯藏期不同殺菌處理即食胡蘿卜片萜烯類和醛類物質(zhì)的百分含量變化Fig.1 Changes in contents of terpenes and aldehydes in prepared carrot slices carrots during refrigerated storage

不同殺菌處理的即食胡蘿卜片在貯藏期間揮發(fā)性成分的種類和百分含量均不同。結(jié)合表1和圖1可知，未殺菌、HHP、PATS、巴氏殺菌處理的即食胡蘿卜片在貯藏初期，萜烯類物質(zhì)質(zhì)量分?jǐn)?shù)分別為40.97%、35.32%、40.96%和32.15%。隨著貯藏時(shí)間的延長(zhǎng)，各處理組的萜烯類化合物的含量整體均呈下降趨勢(shì)。而Kjeldsen F等[7]研究發(fā)現(xiàn)胡蘿卜在冷藏期間萜烯類化合物的含量是增加的，與本研究結(jié)果不一致，可能是因?yàn)檠芯克煤}卜的預(yù)處理不同導(dǎo)致。

未殺菌、HHP、PATS、巴氏殺菌的即食胡蘿卜片在貯藏初期，醛類物質(zhì)百分含量分別是1.65%、1.49%、4.79% 和9.85%。與未殺菌組相比，經(jīng)巴氏殺菌處理后即食胡蘿卜片的醛類含量增加最多，其次為PATS處理組，這是因?yàn)闊釟⒕軌虼龠M(jìn)不飽和脂肪酸氧化生成醛類物質(zhì)[17]。隨著貯藏時(shí)間的延長(zhǎng)，各處理組醛類物質(zhì)呈增加趨勢(shì)，醛類物質(zhì)的增加主要是由于脂肪的氧化降解[11]，且HHP 和PATS處理組醛類物質(zhì)高于巴氏殺菌組，可能是由于高壓處理對(duì)樣品的溶氧量有影響，但還需做進(jìn)一步的研究[17]。

圖2 貯藏期不同殺菌處理即食胡蘿卜片酯類和醇類物質(zhì)的百分含量變化Fig.2 Changes in contents of esters and alkohols in prepared carrot slices carrots during refrigerated storage

結(jié)合表1和圖2可知，在貯藏期不同處理組間酯類物質(zhì)的含量較低且保持相對(duì)穩(wěn)定，主要有左旋乙酸冰片酯。到貯藏后期，PATS和巴氏殺菌組檢測(cè)到少量的乙酸橙花酯和辛酸乙酯。在貯藏期各處理組檢測(cè)到的醇類主要是4-萜烯醇，各處理組的醇類物質(zhì)含量整體呈增加趨勢(shì)，且HHP和PATS處理組高于巴氏殺菌組，可能是由于高壓能夠促進(jìn)萜烯類物質(zhì)氧化生成萜烯醇，進(jìn)而導(dǎo)致高壓處理組的醇類物質(zhì)高于巴氏殺菌組[17]。

圖3 貯藏期不同殺菌處理即食胡蘿卜片酮類物質(zhì)的百分含量變化Fig.3 Changes in contents of ketones in prepared carrot slices carrots during refrigerated storage

結(jié)合表1和圖3可知，α-紫羅蘭酮（紫羅蘭型香氣、花香味）和β-紫羅蘭酮（柏木香氣）是β-胡蘿卜素的降解產(chǎn)物，在未殺菌的即食胡蘿卜片中未檢測(cè)到，而經(jīng)3種殺菌處理的即食胡蘿卜片在貯藏20 d后才開(kāi)始陸續(xù)檢測(cè)到這2種物質(zhì)，且隨著貯藏時(shí)間的延長(zhǎng)不同處理組的酮類物質(zhì)含量總體呈增加趨勢(shì)，其中巴氏殺菌組的增幅最大，說(shuō)明巴氏殺菌組的β-胡蘿卜素?fù)p失最多，這也體現(xiàn)了超高壓殺菌能夠較好地保持產(chǎn)品的營(yíng)養(yǎng)成分，這與Kim Y S[18]研究結(jié)果一致。烷烴類對(duì)胡蘿卜的香氣貢獻(xiàn)不大，其含量相對(duì)比較穩(wěn)定。

2.2 即食胡蘿卜片中幾種特征性萜烯類香氣組分的定量分析

選取胡蘿卜中幾種比較典型的且含量較高的特征萜烯類香氣化合物：β-蒎烯、月桂烯、右旋萜二烯（檸檬烯）、萜品烯（γ-松油烯）、萜品油烯（異松油烯）、β-石竹烯[19-20]，利用標(biāo)準(zhǔn)曲線法進(jìn)行定量分析。由圖4可知，經(jīng)3種殺菌處理的即食胡蘿卜片萜品烯含量隨著貯藏時(shí)間的延長(zhǎng)總體呈下降趨勢(shì)，但HHP處理組含量相對(duì)較高，可能是由于PATS和巴氏殺菌較高的溫度促進(jìn)了萜品烯的氧化反應(yīng)。在貯藏初期，經(jīng)HHP和PATS殺菌后即食胡蘿卜片的β-石竹烯含量降低，巴氏殺菌未發(fā)生變化，可能是由于HHP和PATS處理組的壓力促使酶和底物的接觸，從而誘導(dǎo)酶促反應(yīng)發(fā)生[11]，但還需做進(jìn)一步的研究。而在貯藏期開(kāi)始后只有PATS組的含量呈先增加后降低的趨勢(shì)，在第10天增到164.37 ng/g，直到60d才降低?？赡苁荘ATS由于結(jié)合了高壓和溫度而促使其他萜類物質(zhì)轉(zhuǎn)化生成β-石竹烯，但隨著貯藏時(shí)間的延長(zhǎng)，β-石竹烯又會(huì)發(fā)生氧化反應(yīng)而導(dǎo)致其含量下降[17]，仍需做進(jìn)一步的研究。說(shuō)明在貯藏前期PATS殺菌能夠較好的保持甚至增強(qiáng)胡蘿卜的丁香氣味。

圖4 貯藏期不同殺菌處理即食胡蘿卜片萜品烯和β-石竹烯的含量變化Fig.4 Changes in contents of terpinene and β-caryophyllene in prepared carrot slices carrots during refrigerated storage

由圖5可知，經(jīng)HHP殺菌后的即食胡蘿卜片中右旋萜二烯含量呈先下降又上升后下降的趨勢(shì)，而PATS處理組在貯藏前期呈上升趨勢(shì)，并在第30天時(shí)達(dá)到高峰后又呈下降趨勢(shì)；巴氏殺菌組在第20天時(shí)下降到最低點(diǎn)，且均低于HHP和PATS組。即食胡蘿卜片經(jīng)HHP殺菌后萜品油烯質(zhì)量分?jǐn)?shù)顯著上升達(dá)到108.76 ng/g，比對(duì)照組高21 ng/g，PATS和巴氏殺菌組萜品油烯的含量降低，且在貯藏前30 d，HHP處理組的萜品油烯含量始終高于PATS和巴氏殺菌組?？赡苁怯捎诎褪蠚⒕蚉ATS的高溫均促進(jìn)了萜品油烯的氧化反應(yīng)[17]，因此HHP殺菌較好地保持了即食胡蘿卜片萜品油烯的含量，從而保持胡蘿卜的松木清香味。

由圖6可知，經(jīng)HHP殺菌的即食胡蘿卜片β-蒎烯的含量在貯藏期前10 d均高于未殺菌組；PATS處理組β-蒎烯的含量在整個(gè)貯藏期間保持較高水平；巴氏殺菌組的含量呈現(xiàn)先上升后下降又上升的趨勢(shì)。HHP和PATS處理組的月桂烯含量隨貯藏時(shí)間的延長(zhǎng)呈現(xiàn)先上升后下降的趨勢(shì)，且在貯藏10 d后HHP處理組的月桂烯含量總體高于PATS組，巴氏殺菌處理組總體呈下降趨勢(shì)。說(shuō)明超高壓處理的β-蒎烯和月桂烯的氧化反應(yīng)較熱殺菌弱，在一定程度上較好地保留了胡蘿卜原有的風(fēng)味。這一研究可為新型殺菌技術(shù)在即食產(chǎn)品領(lǐng)域的應(yīng)用提供一定的參考。

圖5 貯藏期不同殺菌處理即食胡蘿卜片右旋萜二烯和萜品油烯的含量變化Fig.5 Changes in contents of D-limonene and terpinolene in prepared carrot slices carrots during refrigerated storage

圖6 貯藏期不同殺菌處理即食胡蘿卜片β-蒎烯和月桂烯的含量變化Fig.6 Changes in contents of β-pinene and myrene in prepared carrot slices carrots during refrigerated storage

與對(duì)照組相比，經(jīng)HHP殺菌處理后即食胡蘿卜片的右旋萜二烯、萜品烯、萜品油烯含量均增加，β-蒎烯的含量變化較小，月桂烯和β-石竹烯的含量有所下降；而PATS處理組除β-蒎烯的含量上升，其他組分均降低，且PATS組降低最多，巴氏殺菌組β-蒎烯和月桂烯的含量上升，其余組分也呈下降趨勢(shì)?？赡苁且?yàn)樵囼?yàn)所用胡蘿卜經(jīng)切分后氧化反應(yīng)已開(kāi)始，再加上熱殺菌促進(jìn)了這些物質(zhì)的氧化反應(yīng)[21]，PATS又結(jié)合超高壓使這一反應(yīng)更加劇烈，但關(guān)于這些物質(zhì)發(fā)生氧化反應(yīng)的機(jī)理還需做進(jìn)一步的研究，而HHP殺菌則較熱殺菌和PATS殺菌在一定程度上較好地保留了胡蘿卜原有的風(fēng)味，而對(duì)即食胡蘿卜片整體品質(zhì)的評(píng)價(jià)還需進(jìn)一步結(jié)合感官試驗(yàn)以及電子舌或電子鼻等儀器檢測(cè)試驗(yàn)[22]。

3 結(jié)論

1）未殺菌、超高壓殺菌、熱輔助超高壓殺菌、巴氏殺菌處理即食胡蘿卜片中分別鑒定出25、24、23和26種組分，包括萜烯類、酯類、醛類、醇類、酮類等，其中萜烯類化合物的種類最多。主要有(1R)-(+)-α蒎烯、莰烯、β-蒎烯、月桂烯、右旋萜二烯、萜品烯、萜品油烯、β-石竹烯等香氣物質(zhì)，構(gòu)成了即食胡蘿卜片青鮮的特殊香氣。

2）定量分析結(jié)果顯示，在60d貯藏期間，各處理組的香氣成分均有變化，共鑒定出41種揮發(fā)性成分，萜烯類物質(zhì)最多，共18種。在貯藏初期，與未殺菌組相比，經(jīng)不同殺菌處理后即食胡蘿卜片的萜烯類物質(zhì)含量均有所降低，其中巴氏殺菌組降低的最多。在貯藏前期（20～30 d），超高壓殺菌處理組的即食胡蘿卜片的萜烯類物質(zhì)的含量較高，其中萜品烯、萜品油烯含量最高，較好地保持了胡蘿卜片清淡的香脂氣味以及松木芳香味，即食胡蘿卜片的風(fēng)味品質(zhì)較好；熱輔助超高壓殺菌技術(shù)處理組的含量次之，熱輔助超高壓殺菌技術(shù)處理組β-蒎烯、β-石竹烯的含量較其他處理組較高，較好地保持了胡蘿卜的松樹(shù)樹(shù)脂香氣以及辛香氣味；而巴氏殺菌組即食胡蘿卜片的萜烯類物質(zhì)含量最低，即食胡蘿卜片的品質(zhì)較差。

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Effect of sterilization methods on volatile flavor compounds of instant carrot slices

Mi Ruifang, Liu Junmei, Hu Xiaosong, Wu Jihong※
(College of Food Science & Nutritional Engineering, China Agricultural University, National Engineering & Technology Research Centre for Fruits & Vegetable Processing, Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture, Beijing 100083, China)

The purpose of this paper was to study the effect of 3 different sterilization methods on the flavor of prepared carrot slices from raw materials during cold storage at 4℃ . The samples were pretreated by pasteurization (90℃ , 30 min), high hydrostatic pressure sterilization (550 MPa, 25℃ , 10 min), pressure-assisted thermal sterilization (550 MPa, 50℃ , 10 min) and stored at 4℃ for 60 d. The solide-phase micro-extraction (SPME)/chromatography-mass spectrometry (GC-MS) technology was used to detect and analyze the volatile flavor compounds in fresh carrot and sterilized carrot slices during storage. Results showed that carrots had a complex volatile characteristic. Fresh carrot sample’s volatiles mainly consisted of terpenes, esters, aldehydes, alcohols, ketones and alkanes. Among these, terpenes were considered to be the most important volatile compounds, such as α-terpinene, terpinolene, β-caryophyllene, β-pinene and D-limonene, which impart the characteristic aroma of fresh carrots. First, a comparison was made between the untreated carrots, pasteurizated carrots, high hydrostatic pressure treated carrots and pressure-assisted thermal treated carrots. In the second step, the volatile compounds of different processing were compared in shelf life of 60 d. The volatile compounds were various in carrot slices during storage, which were treated by different sterilization processing. Firstly, the amount of terpene compounds in each treatment group was declined during the whole storage, and terpenes’ oxidation reactions possibly could be the source of this observation. The level of aldehydes was the highest in pasteurizated carrot slices, but the lowest in high hydrostatic pressure sterilizated carrot slices. Furthermore the content of hexanal, pungent and rancid flavor, was increased significantly during the whole storage. The aldehydes were mainly related to unsaturated fatty acid oxidation. Hence, this suggested that pasteurization might result in a decline in the quality of carrot slices, compared to other treatments. The β-carotene degradation products, α-ionone (violet’s flower aromas) and β-ionone (Cedar’s wood aromas), were detected in sterizated carrot slices 20 d after storage. The level of ionone in high hydrostatic pressure sterilizated carrots was lower than other treatments, which indicated that high hydrostatic pressure sterilization could keep a higher level of β-carotene as well. In other words, the high hydrostatic pressure sterization could keep the quality of carrot slices better. In addition, the levels of esters and alkanes had less change during the storage. The main alcohol was 4-terpineol, the oxidation product of terpinolene. The content of terpenoids decreased after sterilization treatment. And it was higher in high hydrostatic pressure and pressure-assisted thermal sterilizated carrots compared to pasteurizated carrots in 30 d, which might be due to the thermal processing inducing terpinene oxidation. However, the content of β-caryophyllene decreased obviously in high hydrostatic pressure and pressure-assisted thermal sterilizated carrot slices. Pressure could induce membrane damage and bring enzymes and substrates into contact, which would not or less occur during thermal processing. And high hydrostatic pressure sterilizated carrot slices had a higher level of myrcene and terpinolene at earlier storage compared with others, which resulted in a better light balsam smell and pine fragrance kept. Pressure-assisted thermal sterilizated carrot slices had a higher content of β-pinene and β-caryophyllene, and there was better pine resin and spicy aroma. The quality of high hydrostatic pressure sterilizated and pressure-assisted thermal sterilizated carrot slices was superior to pasteurizated carrot slices. The results can provide a reference for the applications of new sterilization technologies in ready-to-eat products.

sterilization; storage; flavors; prepared carrot slices; high hydrostatic pressure sterilization; pressure-assisted thermal sterilization; pasteurization

10.11975/j.issn.1002-6819.2016.09.037

TS255.36

A

1002-6819(2016)-09-0264-07

米瑞芳，劉俊梅，胡小松，吳繼紅. 殺菌方式對(duì)即食胡蘿卜片揮發(fā)性風(fēng)味物質(zhì)的影響[J]. 農(nóng)業(yè)工程學(xué)報(bào)，2016，32(9)：264－270.

10.11975/j.issn.1002-6819.2016.09.037 http://www.tcsae.org

Mi Ruifang, Liu Junmei, Hu Xiaosong, Wu Jihong. Effect of sterilization methods on volatile flavor compounds of instant carrot slices[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2016, 32(9): 264－270. (in Chinese with English abstract) doi：10.11975/j.issn.1002-6819.2016.09.037 http://www.tcsae.org

2015-08-24

2016-03-15

北京市科技計(jì)劃課題（Z131100003113001）；國(guó)家支撐計(jì)劃課題（2014BAD04B04）

米瑞芳，女，陜西人，主要從事果蔬食品風(fēng)味化學(xué)方面研究。北京 中國(guó)農(nóng)業(yè)大學(xué)食品科學(xué)與營(yíng)養(yǎng)工程學(xué)院，國(guó)家果蔬加工工程技術(shù)研究中心，農(nóng)業(yè)部果蔬加工重點(diǎn)開(kāi)放實(shí)驗(yàn)室，100083。Email：ruifangmi216@163.com

※通信作者：吳繼紅，女，教授，博士生導(dǎo)師，2011年赴美國(guó)伊利諾伊大學(xué)訪問(wèn)研究，主要從事果蔬食品風(fēng)味化學(xué)方面研究。北京 中國(guó)農(nóng)業(yè)大學(xué)食品科學(xué)與營(yíng)養(yǎng)工程學(xué)院，國(guó)家果蔬加工工程技術(shù)研究中心，農(nóng)業(yè)部果蔬加工重點(diǎn)開(kāi)放實(shí)驗(yàn)室，100083。Email：wjhcau@hotmail.com