荊佳伊,劉曉佳,鄧麗莉,2,姚世響,2,曾凱芳,2
采收成熟度對(duì)晚熟W.默科特柑橘貯藏期品質(zhì)的影響
荊佳伊1,劉曉佳1,鄧麗莉1,2,姚世響1,2,曾凱芳1,2※
(1. 西南大學(xué)食品科學(xué)學(xué)院,重慶 400715; 2. 西南大學(xué)食品貯藏與物流研究中心,重慶 400715)
W.默科特(Blanco)是中國(guó)重要的晚熟柑橘品種,為探究成熟度對(duì)果實(shí)品質(zhì)及耐貯性的影響,以7個(gè)不同采收期(分別為11月25日,12月10日,12月24日,翌年1月7日,1月21日,2月7日以及2月19日采樣)的W. 默科特果實(shí)為試驗(yàn)材料,對(duì)采收點(diǎn)及冷庫(kù)貯藏期間(0~150 d)的色澤、糖酸組分、抗壞血酸含量、含水率、硬度、失重率及腐爛率等進(jìn)行測(cè)定。在采收點(diǎn),2月7日采收的柑橘果實(shí)完全轉(zhuǎn)黃,抗壞血酸含量、可溶性固形物含量及固酸比均最高。冷庫(kù)貯藏期間,11月25日采收的果實(shí)可溶性固形物含量低,轉(zhuǎn)色較慢;12月下旬和1月上旬采收的果實(shí)在貯藏期間未發(fā)生腐敗變質(zhì),失重率均在5%左右,其中12月下旬采收的果實(shí)硬度降幅最低且抗壞血酸含量比其他采收期高。研究表明,鮮銷(xiāo)及冷藏的W.默科特果實(shí)的較佳采收期分別為翌年2月上旬及12月中下旬。研究結(jié)果為柑橘果實(shí)適時(shí)采收提供參考。
貯藏;品質(zhì)控制;成熟度;W.默科特;采收期;品質(zhì)變化
W.默科特又名W.Murcott 或Fourier,美國(guó)育成,是橘與甜橙的雜交品種,可溶性固形物含量平均為12.5%,酸含量平均為0.76%,無(wú)籽或含少量籽,易剝皮,深受消費(fèi)者喜愛(ài)[1-2]。在中國(guó)柑橘市場(chǎng)中,中熟柑橘品種多而早熟晚熟柑橘少,晚熟柑橘W.默科特可掛果至翌年3月,可起到調(diào)節(jié)市場(chǎng)的作用,有利于柑橘產(chǎn)業(yè)的可持續(xù)發(fā)展[3]。近年來(lái),對(duì)新引進(jìn)品種W.默科特的研究多集中于保鮮方法[4],采前栽培技術(shù)[5],不同地區(qū)果實(shí)品質(zhì)差異[1]等方面,而對(duì)適時(shí)采收的研究鮮有報(bào)道。
據(jù)報(bào)道,果實(shí)的成熟度與果實(shí)品質(zhì)及采后耐貯性密切相關(guān)。對(duì)葡萄[6],油桃[7],獼猴桃[8],香蕉[9]等各類(lèi)果實(shí)的研究表明,適時(shí)采收有利于延長(zhǎng)果實(shí)貯藏期并提高果實(shí)品質(zhì)。過(guò)早采收的果實(shí),糖含量較低,口感酸澀,顏色偏綠,外觀品質(zhì)較差;而較晚采收的果實(shí),貯藏過(guò)程中更容易腐爛,造成較大的經(jīng)濟(jì)損失。據(jù)報(bào)道,不同品種的柑橘,其采收時(shí)間也不盡相同。不知火桔橙果實(shí)在2月中旬采摘,可貯藏60 d,而3月份采摘僅可短期30 d以?xún)?nèi)貯藏[10];冷藏的紐荷爾臍橙最適采摘期為11月中旬到12月上旬[11];對(duì)成都地區(qū)的雜柑采收期相關(guān)試驗(yàn)表明,愛(ài)媛21的最佳采收期為11月中旬,南香、愛(ài)媛22、愛(ài)媛30、愛(ài)蜜柑的最佳采收期為12月上旬,天草、壽柑的最佳采收期為12月下旬,春見(jiàn)的最佳采收期在次年1月下旬[12]。
為探究W.默科特在中國(guó)西南地區(qū)適宜鮮銷(xiāo)及貯藏后銷(xiāo)售的較佳采收時(shí)間,本研究以重慶江津地區(qū)為試驗(yàn)點(diǎn),以在11月中下旬到翌年2月中下旬采收的晚熟柑橘W.默科特作為試驗(yàn)試材,選取了一系列理化指標(biāo)作為評(píng)價(jià)標(biāo)準(zhǔn),對(duì)不同采收期的果實(shí)品質(zhì)及其低溫貯藏150 d內(nèi)的品質(zhì)變化規(guī)律進(jìn)行了分析,探討果實(shí)掛樹(shù)期間的品質(zhì)變化,分析適宜鮮銷(xiāo)的果實(shí)采收時(shí)間;探討采收期對(duì)采后耐貯性的影響及貯藏期間的品質(zhì)變化規(guī)律,分析適宜貯藏后銷(xiāo)售的果實(shí)采收時(shí)間,以期為W.默科特果實(shí)在西南地區(qū)的采收時(shí)間提供參考。
1.1.1 材料
供試果實(shí)為晚熟W.默科特柑橘,采自重慶市江津區(qū)。
1.1.2 處理方法
如表1所示,果實(shí)試驗(yàn)共設(shè)7個(gè)采收期,果實(shí)采收后立即運(yùn)回實(shí)驗(yàn)室,挑選顏色和大小一致、無(wú)機(jī)械傷、無(wú)病蟲(chóng)害的果實(shí)作為試驗(yàn)試材,采收當(dāng)天測(cè)定果實(shí)相關(guān)指標(biāo),并對(duì)果實(shí)進(jìn)行取樣用液氮速凍后置于?40 ℃冰箱保存。
用于貯藏試驗(yàn)的果實(shí),用2%次氯酸鈉溶液浸泡果實(shí)2 min進(jìn)行表面消毒,隨后置于清水用紗布小心擦洗干凈果皮,再用500倍稀釋的柑橘保鮮劑真綠色和200 mg/L的2,4-D混合液浸泡果實(shí)2 min,自然晾干,最后用柑橘用PU薄膜單果包裝,包裝后的果實(shí)隨機(jī)分為3組,低溫(8~10 ℃、相對(duì)濕度80%~85%)貯藏于冷庫(kù)。果實(shí)在貯藏0,15,30,45,60,75,90,105,120,135和150 d進(jìn)行取樣,測(cè)定相關(guān)指標(biāo)。每個(gè)處理用果45個(gè),重復(fù)3次。
表1 采收期與采收時(shí)間的對(duì)應(yīng)關(guān)系
1.1.3 果皮色澤分級(jí)測(cè)定
果皮色澤的分級(jí)標(biāo)準(zhǔn)與測(cè)定方法如表2所示[13],其公式如下:
果皮色澤分級(jí)指數(shù)=Σ(色澤級(jí)別×該級(jí)別果實(shí)占總果實(shí)的百分比) (1)
表2 果實(shí)色澤變化分級(jí)標(biāo)準(zhǔn)
每個(gè)處理用果45個(gè),重復(fù)3次。
1.1.4 果皮色差值測(cè)定
采用UltraScan? PRO色差儀(美國(guó)HunterLab公司)測(cè)量,分別測(cè)定果實(shí)果皮赤道部位的亮度L、紅綠度a和黃藍(lán)度b值。每個(gè)處理測(cè)15個(gè)果實(shí),每個(gè)果實(shí)測(cè)3點(diǎn),求3點(diǎn)平均值作為該果實(shí)色差值[14]。柑橘色差指數(shù)CCI如下式[15]:
CCI=1 000/(·)(2)
1.1.5 果實(shí)理化指標(biāo)測(cè)定
果實(shí)含水率測(cè)定:果實(shí)含水率測(cè)定參考曹建康等[16]的方法,用質(zhì)量分?jǐn)?shù)(%)表示,重復(fù)測(cè)定3次。
果實(shí)硬度測(cè)定:采用質(zhì)構(gòu)儀進(jìn)行,試驗(yàn)所用探頭為T(mén)A/39。將果實(shí)置于質(zhì)構(gòu)儀探頭下方做TPA試驗(yàn),測(cè)定部位為果實(shí)赤道,在赤道部位等距離測(cè)定3次。試驗(yàn)參數(shù)設(shè)置為探頭預(yù)壓速度2.00 mm/s,下壓速度1.00 mm/s,壓后上升速度2.00 mm/s,2次壓縮間停頓2.00 s,試樣受壓變形5 %,以3點(diǎn)的平均值作為該果實(shí)硬度,3次重復(fù),進(jìn)行統(tǒng)計(jì)分析。
果實(shí)抗壞血酸含量的測(cè)定參考 Mditshwa等[17]的方法,試驗(yàn)重復(fù)3次。果實(shí)中抗壞血酸含量以mg/100 g表示,按式(3)計(jì)算:
抗壞血酸含量=100·(1?0) ·/(v·)(3)
式中為樣液定容體積,100 mL;1為樣液滴定消耗的染料體積,mL;0為空白滴定消耗的染料體積,mL;為1 mL染料溶液相當(dāng)于抗壞血酸的質(zhì)量,mg/mL;v為滴定時(shí)吸取樣品溶液的體積,mL;為稱(chēng)取樣品的質(zhì)量,g。
果實(shí)可溶性固形物含量測(cè)定:參照曹建康等[16]的方法,并適當(dāng)改進(jìn)。取8~10個(gè)果實(shí),將果肉放入榨汁機(jī)榨汁,過(guò)濾,收集果汁。用塑料滴管吸取濾液,用數(shù)顯手持式折光儀測(cè)定樣品的可溶性固形物的含量,以質(zhì)量分?jǐn)?shù)(%)表示,重復(fù)3次。
果實(shí)可滴定酸含量測(cè)定:可滴定酸含量的測(cè)定參考曹建康等[16]的方法并做適當(dāng)修改,用NaOH滴定法測(cè)定。重復(fù)3次。以蒸餾水代替果汁,用NaOH溶液滴定,作為試驗(yàn)空白對(duì)照??傻味ㄋ岷坑觅|(zhì)量分?jǐn)?shù)(%)表示,按式(4)計(jì)算:
可滴定酸含量=(′··(′1?′0) ·/′) ×100%(4)
式中′為樣品定容體積,mL;為氫氧化鈉標(biāo)定液濃度,mol/L;1′為滴定樣液消耗的氫氧化鈉溶液的體積,mL;0′為滴定蒸餾水消耗的氫氧化鈉溶液的體積,mL;為折算系數(shù),g/mmoL,柑橘果實(shí)以檸檬酸計(jì),=0.064;v′為滴定時(shí)所取樣液體積,mL。
果實(shí)糖酸組分及含量測(cè)定:果實(shí)中糖酸含量的測(cè)定參考Yun等[18]方法并作適當(dāng)修改。準(zhǔn)確稱(chēng)取0.3 g果實(shí)樣品,加入液氮充分研磨成粉末,加入2.7 mL?20 ℃預(yù)冷的甲醇,搖勻后加入0.3 mL(0.2 mg/mL)核糖醇內(nèi)標(biāo),混勻后將樣品置于超聲波中4 ℃處理15 min,樣品再置于70 ℃水浴15 min,待樣品冷卻后置于4 ℃,5 000離心20 min,吸取上清液100L真空濃縮至干后放于?80 ℃冰箱保存。
試驗(yàn)所用的色譜柱為DB-5MS(安捷倫科技(中國(guó))有限公司)石英毛細(xì)管柱(30 m×0.25 mm ID,0.25m),載氣為氦氣(純度為99.999%),載氣流速1.0 mL/min,壓力為73 kPa,分流比10,掃描范圍45~600 m/z,離子源溫度230 ℃,進(jìn)樣口溫度250 ℃,接口溫度250 ℃,進(jìn)樣量1L。
升溫程序?yàn)椋撼跏紲囟?00 ℃保持1 min,3 ℃/min升至175 ℃保持1 min;以2 ℃/min至184 ℃,0.5 ℃/min升到190 ℃保持1 min;7 ℃/min升至280 ℃保持5 min。
定性分析根據(jù)所得到的質(zhì)譜圖與NIST08和NIST08S數(shù)據(jù)庫(kù)中的標(biāo)準(zhǔn)譜圖及NIST(http://webbook.nist.gov/chemistry/)進(jìn)行比對(duì),得到果實(shí)所含糖酸的初步定性報(bào)告,再結(jié)合劉淑楨等[19]、Yun等[20]和Zhang等[21]的試驗(yàn)結(jié)果進(jìn)一步對(duì)果實(shí)所含糖酸進(jìn)行定性分析。采用內(nèi)標(biāo)物對(duì)果實(shí)各成分進(jìn)行半定量分析。
果實(shí)失重率測(cè)定:采用稱(chēng)重法[22],每個(gè)處理用果30個(gè),重復(fù)3次。計(jì)算公式如下:
果實(shí)腐爛率測(cè)定:每個(gè)處理用果30個(gè),重復(fù)3次。計(jì)算公式如下:
所有數(shù)據(jù)用Graphpad Prism 5.0軟件記錄、分析并繪圖;用SPSS17.0軟件對(duì)數(shù)據(jù)進(jìn)行方差分析(ANOVA),利用Duncan’s多重比較對(duì)數(shù)據(jù)差異顯著性分析,<0.05表示差異顯著。
2.1.1 不同采收期W.默科特果實(shí)基本品質(zhì)的變化
如表3所示,隨著采收期的延長(zhǎng),果實(shí)的色澤指數(shù)先快速上升后趨于穩(wěn)定。在第III采收期及之后,果實(shí)轉(zhuǎn)色面積達(dá)到80%。*、*和*分別代表亮度,紅綠度和黃藍(lán)度,隨采收時(shí)間的延后,果皮顏色從綠色轉(zhuǎn)為黃色、橙黃色、橙紅色,這體現(xiàn)了果實(shí)成熟度的變化[23]。*在前5個(gè)采收期波動(dòng)上升,在第V采收期達(dá)到峰值,后趨于平穩(wěn);*在I-IV采收期上升迅速,在第V采收期有所回落,而后又迅速上升至最高值;*在第V采收期達(dá)到最高值。
含水率在整個(gè)采收初期變化較明顯,采收中后期含水率變化緩慢,整體呈下降趨勢(shì)。硬度在采收初期I-II和末期VI-VII下降迅速,而在采收期II-VI期間變化不顯著。采收結(jié)束時(shí),果實(shí)硬度由采收期I的628.50 g降為采收期VII的346.00 g,降幅為44.9%。抗壞血酸含量在采收初期I-II果實(shí)抗壞血酸含量顯著(<0.05)升高,之后降低,在采收期V之后又呈上升趨勢(shì),采收期VI時(shí)達(dá)到最高,為21.15 mg/100 g。
表3 不同采收期W.默科特果實(shí)的品質(zhì)變化
注:不同小寫(xiě)字母表示在=0.05水平上差異顯著。
Note: Different lowercase letters after the data in the same column indicate the significance at=0.05 level.
可溶性固形物含量隨著采收期的延長(zhǎng)呈先上升后降低趨勢(shì),在采收期VI達(dá)到最高值11.60%。在采收期I-III果實(shí)可滴定酸含量顯著(<0.05)降低,采收期V后果實(shí)可滴定酸含量顯著(<0.05)降低,在采收期VI達(dá)到最低,為采收期I的73.6 %。隨著采收期的延遲,果實(shí)固酸比先快速上升,在采收期VI達(dá)到最高為17.45,之后呈顯著(<0.05)降低趨勢(shì)。
2.1.2 不同采收期W.默科特果實(shí)可溶性糖及有機(jī)酸含量的變化
由圖1所示,果實(shí)中共檢測(cè)到8種可溶性糖,分別為蔗糖、果糖、葡萄糖、半乳糖、甘露糖、吡喃葡萄糖、核糖和木糖。其中果糖、蔗糖、甘露糖、吡喃葡萄糖、核糖和木糖含量均隨著采收期的延長(zhǎng)呈先上升后降低的趨勢(shì)。果糖、蔗糖和木糖含量在采收期VI達(dá)到最高;甘露糖、核糖含量分別在在采收期V和III達(dá)到最高;吡喃葡萄糖在采收期I未檢測(cè)出,采收期II-IV雖有上升但變化不顯著(>0.05);葡萄糖和半乳糖含量均隨著采收期的延遲呈持續(xù)上升趨勢(shì),在采收期VI前變化顯著(<0.05),采收期VI后趨于穩(wěn)定。
由圖2所示,果實(shí)中共檢測(cè)到9種有機(jī)酸,分別為檸檬酸、蘋(píng)果酸、草酸、丙酸、富馬酸、葡萄糖酸、-酮戊二酸、琥珀酸和烏頭酸。隨著采收期的延遲檸檬酸和烏頭酸含量總體上呈現(xiàn)降低的趨勢(shì)。果實(shí)烏頭酸含量在采收期I-IV基本無(wú)變化,之后顯著(<0.05)降低,在采收期VI達(dá)到最低。果實(shí)中的蘋(píng)果酸、草酸、丙酸、富馬酸、葡萄糖酸、-酮戊二酸和琥珀酸含量均隨著采收期的延遲呈先上升后降低趨勢(shì)。采收期VII與I相比,琥珀酸含量升高,丙酸、富馬酸、葡萄糖酸含量基本不變,蘋(píng)果酸、草酸和-酮戊二酸含量降低。
2.2.1 W.默科特果實(shí)在貯藏期間的顏色和硬度變化
圖3為低溫貯藏過(guò)程中的色澤指數(shù)和硬度的變化情況。采收期I的果實(shí)在貯藏45 d果實(shí)轉(zhuǎn)黃面積達(dá)到80.0 %以上,在貯藏120 d時(shí),果實(shí)全部轉(zhuǎn)黃。采收期II的果實(shí)在貯藏60 d時(shí)果實(shí)全部轉(zhuǎn)黃。在低溫貯藏過(guò)程中硬度總體呈現(xiàn)降低趨勢(shì),而在貯藏結(jié)束時(shí),采收期I的果實(shí)硬度顯著高于采收期II-VII的果實(shí),采收期VII的果實(shí)硬度最低。采收期I-IV的果實(shí)在貯藏過(guò)程硬度降幅小。
2.2.2 W.默科特果實(shí)在貯藏期間失重與相對(duì)水分含量變化
圖4為低溫貯藏過(guò)程中的失重率和腐爛率的變化情況。
隨著貯藏時(shí)間延長(zhǎng),果實(shí)失重率呈上升趨勢(shì)。不同采收期的果實(shí)在貯藏結(jié)束時(shí),失重率均在5.0%左右,表明低溫貯藏的果實(shí)失重低,果實(shí)品質(zhì)保持好。在貯藏150 d時(shí)采收期V的果實(shí)失重率較高,采收期I和VII次之。采收期V和VII的果實(shí)在貯藏135 d和45 d開(kāi)始發(fā)生腐爛,貯藏結(jié)束時(shí),采收期V的果實(shí)腐爛率為3.33%(<0.05),采收期VII的果實(shí)腐爛率為16.67%,二者差異顯著;其余采收期的果實(shí)在低溫貯藏過(guò)程中腐爛率均為0。
2.2.3 W.默科特果實(shí)在貯藏期間的可溶性固形物、可滴定酸和抗壞血酸含量變化
圖5為低溫貯藏過(guò)程中的可溶性固形物,可滴定酸和抗壞血酸含量的變化情況。采收期I-V的果實(shí)隨著貯藏時(shí)間的延長(zhǎng),可溶性固形物含量呈先上升后降低趨勢(shì),采收期I-III的果實(shí)可溶性固形物含量低于其他采收期。不同采收期的果實(shí)隨貯藏時(shí)間延長(zhǎng),可滴定酸含量均降低。早采果實(shí)酸含量高于晚采果實(shí),但是過(guò)早和過(guò)晚采收的果實(shí)在貯藏過(guò)程中酸含量容易損失。采收期III的果實(shí)在貯藏過(guò)程中保持了較高水平的可滴定酸含量??箟难岷空w呈降低趨勢(shì),貯藏結(jié)束時(shí),采收期I-VII的果實(shí)抗壞血酸含量分別是貯藏前的84.7%、69.9%、77.3%、64.8%、70.2%、53.5%和52.3%,其中采收期I和III的果實(shí)較其他采收期果實(shí)能更好的保持貯藏過(guò)程中的抗壞血酸含量。
W.默科特是重要的晚熟柑橘品種,果實(shí)品質(zhì)優(yōu)良,不?;讋兤?,產(chǎn)量高[24]。消費(fèi)者較關(guān)注新鮮水果的營(yíng)養(yǎng)、感官品質(zhì),而不同采收期的營(yíng)養(yǎng)物質(zhì)累積和植物化學(xué)物質(zhì)的量不同會(huì)對(duì)其造成影響[25-26]。大多數(shù)果蔬的采后和貯藏期間的品質(zhì)變化也與其采收的時(shí)間顯著相關(guān)[27]。研究表明,貯藏初期,較早采收果實(shí)的可溶性固形物、抗壞血酸、可滴定酸含量較低,而較晚采收則會(huì)導(dǎo)致果實(shí)貯藏過(guò)程中硬度的降幅增大以及腐爛率增加[28]。因此,需要根據(jù)不同需要確定合適的采收期。表面色澤與固酸比為柑橘成熟度指標(biāo),可為果實(shí)的無(wú)損檢測(cè)提供依據(jù)[29]。
本試驗(yàn)中,剛采收的果實(shí)色澤指數(shù)隨采收期延長(zhǎng)呈先快速上升后緩慢變化的趨勢(shì),果實(shí)在采收期III時(shí)轉(zhuǎn)色已達(dá)到80.0%,在色澤上達(dá)到了采摘要求。色差值(*、*、*)隨采收期延長(zhǎng)先迅速升高,后緩慢變化,表明果實(shí)在采收期I時(shí)還不成熟。*、*值在采收后期呈升高趨勢(shì),表明晚采的果實(shí)亮度和黃度升高,其中果皮亮度的升高可能是類(lèi)胡蘿卜素積累的結(jié)果[30]。低溫貯藏期間,采收期I-III的果實(shí)分別在低溫貯藏105,75,45 d完全轉(zhuǎn)黃(CI=6),在貯藏結(jié)束時(shí),各采收期果實(shí)色澤無(wú)顯著差異(>0.05)。
隨著采收期延遲,果實(shí)硬度總體呈降低趨勢(shì),其中采收期I-II、采收期VI-VII變化顯著(<0.05)。低溫貯藏的果實(shí),隨著后熟,果實(shí)中的原果膠在果膠酶的作用下轉(zhuǎn)變?yōu)榭扇苄怨z[31],導(dǎo)致貯藏期間硬度降低。在貯藏結(jié)束時(shí),采收期I-IV的果實(shí)硬度降幅較小,表明早采有利于貯藏過(guò)程中的硬度保持。
果實(shí)的可溶性固形物、可滴定酸、抗壞血酸等的含量構(gòu)成了果實(shí)的內(nèi)在品質(zhì)。果實(shí)可溶性固形物含量隨成熟度的變化,先升高后降低,在采收期VI達(dá)到最高,這與劉洋[29]的研究結(jié)果相似。果實(shí)在11月下旬到翌年2月上旬采收,可溶性固形物含量升高或與體內(nèi)淀粉轉(zhuǎn)化為可溶性糖有關(guān),而在2月中下旬采收,可溶性固形物含量降低與果實(shí)呼吸作用消耗體內(nèi)有機(jī)物有關(guān)[32]??傻味ㄋ岷靠傮w呈降低趨勢(shì);固酸比在采收過(guò)程中先升高后降低,在采收期VI最高,這一時(shí)期的抗壞血酸含量也比其他采收期更高。W.默科特果肉中含有8種糖和9種有機(jī)酸。葡萄糖在采收過(guò)程含量升高,果糖、蔗糖含量先升高在采收期VI達(dá)到最高,之后呈降低趨勢(shì)。檸檬酸含量總體降低,果實(shí)檸檬酸含量的變化直接導(dǎo)致果實(shí)風(fēng)味的改變和可滴定酸含量的降低。
在低溫貯藏過(guò)程中,采收期I-III的果實(shí)可溶性固形物含量較低,可滴定酸含量隨著貯藏期延長(zhǎng)呈降低趨勢(shì),采收期III的果實(shí)在貯藏過(guò)程中很好保持了酸含量。在貯藏結(jié)束時(shí)(150 d)12月24日采收的果實(shí)抗壞血酸含量(15.27 mg/100 g)與可滴定酸含量(0.37%)最高,可溶性固形物含量(9.6%)較高,硬度保持較好(376 g),貯藏過(guò)程中可滴定酸含量的降低可能與果實(shí)呼吸消耗酸有關(guān),也可能和酸轉(zhuǎn)變?yōu)槠渌镔|(zhì)有關(guān)。果實(shí)失重率在貯藏結(jié)束時(shí)均在5.0 %左右。采收期VII和V的果實(shí)分別在低溫貯藏第45天和135天開(kāi)始出現(xiàn)腐爛,表明較晚采收的果實(shí)更容易在貯藏中出現(xiàn)病害。
1)12月下旬及之后采收的果實(shí)在顏色上達(dá)到采摘要求,其中12月下旬至翌年2月上旬采收的果實(shí)硬度較好,固酸比和抗壞血酸含量均在2月上旬達(dá)到最高,且果實(shí)的果糖、蔗糖、檸檬酸含量也相對(duì)較高,因此,7個(gè)采收期中,2月7日采收的果實(shí)在采摘時(shí)綜合品質(zhì)較佳,適合鮮銷(xiāo)。
2)各采收期果實(shí)在低溫貯藏過(guò)程中失重率均較低,貯藏結(jié)束時(shí)果皮顏色差異不顯著(>0.05)。11月下旬采收的果實(shí)可溶性固形物含量遠(yuǎn)低于其余采收期,1月下旬到2月下旬采收的果實(shí)在貯藏過(guò)程中出現(xiàn)病害,而12月上旬到翌年1月上旬采收的果實(shí)在貯藏結(jié)束時(shí)硬度保持較好且均在低溫貯藏150 d不腐敗變質(zhì),其中12月下旬采收的果實(shí)更好地保持了可滴定酸和抗壞血酸含量。因此,7個(gè)采收期中,12月24日采收的果實(shí)在貯藏過(guò)程中綜合品質(zhì)較佳,適合貯藏后銷(xiāo)售。
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Effects of harvesting maturity on the quality changes during storage of late maturing W.Murcott
Jing Jiayi1, Liu Xiaojia1, Deng Lili1,2, Yao Shixiang1,2, Zeng Kaifang1,2※
(1.,400715,; 2.400715,)
W. Murcott (Blanco) is a variety of late-maturing mandarin in Chongqing of China that has been imported from the United States. There are more medium ripe citrus varieties, but fewer early or late ripe ones in the market. Late ripe W. Murcott can be held until March of the next year for better sustainable development of the citrus industry. In this study, the parameters were measured, including the color, sugar and acid components, ascorbic acid content, relative water content, firmness, weight loss rate, and rot rate of the fruits in seven harvesting periods during cold storage (0 - 150 days), thereby determining the effect of ripening on fruit quality and storability. Every 45 fruits were selected as a group, and three groups were taken in parallel for the determination of relevant indexes every 15 days. Graphpad Prism 5.0 software was selected to plot all recorded data. Analysis of variance (ANOVA) was performed on a SPSS17.0 software, and Duncan's multiple comparison was used to analyze the different significance. The results showed that the citrus fruits turned yellow completely in the VI harvest period at the time of harvest (day 0 of storage), where the ascorbic acid content, soluble solid content, and solid-acid ratio were the highest. The soluble solids content of fruits in the harvest period I was low, and the color changed slowly during the storage time. The fruits in the harvest period of V-VII were rotted during storage. In the harvest period of III and IV, the fruits did not deteriorate, where the weight loss rate was less than 5%, and the ascorbic acid content was higher than that in other harvest periods at the end of storage. There were 8 kinds of soluble sugar and 9 kinds of organic acid in the fruit during the storage. The contents of fructose, sucrose, mannose, pyranose, ribose, and xylose all increased first and then decreased with the extension of the harvest period. The content of citric acid and aconite acid decreased with the delay of the harvesting period. The content of aconite acid in fruit was basically unchanged in the period of I-IV, and then decreased significantly during storage. It reached the lowest in the VI harvest period. The contents of malic acid, oxalic acid, propionic acid, fumaric acid, gluconic acid,-ketoglutaric acid, and succinic acid in fruits all increased at first and then decreased with the delay of the harvesting period. In general, the harvest time needed to be adjusted to different commercial demands. The findings herein demonstrated that the fruit of harvest period VI (Feb. 7th) had complete color transformation while the soluble solid (11.60%) and ascorbic acid content (21.15 mg/100 g) were high, and the solid acid ratio (17.45) was optimal, suitable for fresh market. The decay rate of fruits in the harvest period III (Dec. 24th) was 0 after 150 days of storage. The highest content of ascorbic acid (15.27 mg/100 g) and titratable acid (0.37%) was achieved at the end of low-temperature storage, with the high content of soluble solids (9.6%), while the firmness remained better (376 g), suitable for post-storage sales.
storage; quality control; maturity; W. Murcott; harvest period; storage time; quality changes
荊佳伊,劉曉佳,鄧麗莉,等. 采收成熟度對(duì)晚熟W.默科特柑橘貯藏期品質(zhì)的影響[J]. 農(nóng)業(yè)工程學(xué)報(bào),2021,37(5):303-309.doi:10.11975/j.issn.1002-6819.2021.05.035 http://www.tcsae.org
Jing Jiayi, Liu Xiaojia, Deng Lili, et al. Effects of harvesting maturity on the quality changes during storage of late maturing W.Murcott[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2021, 37(5): 303-309. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2021.05.035 http://www.tcsae.org
2020-09-17
2021-02-27
國(guó)家自然科學(xué)基金資助項(xiàng)目(31772027);重慶市技術(shù)創(chuàng)新與應(yīng)用發(fā)展專(zhuān)項(xiàng)重點(diǎn)項(xiàng)目(cstc2019jscx-dxwtBX0027)
荊佳伊,研究方向?yàn)槭称飞锛夹g(shù)。Email:xndxjjy@163.com
曾凱芳,博士,教授,研究方向?yàn)檗r(nóng)產(chǎn)品貯藏工程。Email:zengkaifang@163.com
10.11975/j.issn.1002-6819.2021.05.035
TS255.3
A
1002-6819(2021)-05-0303-07
農(nóng)業(yè)工程學(xué)報(bào)2021年5期