银条(Stachys flordana Schuttl.ex Benth)属于唇形科水苏属,是一种多年生草本植物,主要食用部位是地下根茎。银条是河南省洛阳市偃师的地理标志性产品[1],食用和药用价值极高,不仅富含膳食纤维、维生素、矿物质等众多营养物质,还含有多种生理活性物质,例如水苏糖、胆碱、葫芦巴碱等,可以起到降血糖、降血脂、调节免疫力等作用,开发利用前景较佳[2]。然而,银条颜色洁白,脆嫩多汁,采后极易发生酶促褐变而导致其外观品质劣变及营养价值降低,造成极大经济损失,严重制约了银条产业的发展[3]。因此,如何控制银条褐变的发生是银条贮藏及加工中亟待解决的问题。

采后果蔬衰老或者在低温胁迫条件下,果蔬细胞膜结构会损伤并破坏,导致多酚类物质与多酚氧化酶(polyphenol oxidase,PPO)接触并被其氧化成醌,引发酶促褐变[4]。有研究认为,果蔬贮藏中的能量亏缺能引起细胞膜的损伤,加速采后果蔬酶促褐变的发生。LIN等[5]认为H2O2处理加剧龙眼果皮褐变主要是由于降低了龙眼果皮三磷酸腺苷(adenosine triphosphatase,ATP)酶活性和ATP含量。ZHANG等[6]和CHEN等[7]研究表明,采用外源ATP处理可提高南果梨和龙眼果实ATP含量及能荷水平,较好地维持果实酚类物质与PPO的区室化分布,有效抑制两者结合,降低了南果梨和龙眼果实褐变的发生。WANG等[8]和蔺凯丽等[9]研究发现,褪黑素和麦角硫因处理降低荔枝和双孢蘑菇褐变与其提高果蔬体内能量水平有关。由此可见,果蔬贮藏中能量代谢水平与其褐变的发生密切相关。

草酸是一种分布于果蔬体内的二元有机酸,具有提高采后果蔬抗氧化能力、延缓衰老进程、减轻木质化程度、降低冷害发生等作用,对果蔬的多种代谢活动具有调控效果,可提高果蔬贮藏品质[10-12]。很多文献研究表明,草酸处理对采后果蔬褐变的发生具有抑制作用,如LI等[13]采用草酸降低了芒果果肉褐变;SHAFIQUE等[11]采用草酸降低了采后荔枝果皮褐变;ALI等[14]和BIN等[15]采用草酸抑制了莲藕和黄金果褐变。本课题组前期研究表明,银条在10 ℃下褐变程度较4 ℃低,10 ℃是银条的最佳贮藏温度[2];5 mmol/L草酸处理能显著降低芒果果肉褐变[13];10 mmol/L草酸处理能维持番茄低温贮藏较高ATP和二磷酸腺苷(adenosine diphosphate,ADP)含量从而降低番茄冷害程度[16]。然而,目前草酸处理对采后银条褐变及能量代谢的影响还未见报道,尤其是褐变与能量代谢之间的关系还未被阐明。因此,本试验以银条为材料,研究草酸处理对低温贮藏下银条酶促褐变、能量代谢的影响,探讨草酸处理对采后银条褐变的影响,并揭示其与能量代谢的关系,本研究可为草酸处理调控银条的褐变提供理论依据。

1 材料与方法

1.1 材料与试剂

银条(品种为“两细一粗”)购于河南省洛阳市偃师许庄村。草酸、福林酚、邻苯二酚、腺苷单磷酸(adenosine monophosphate,AMP)、ADP、ATP、细胞色素c、L-苯丙氨酸、愈创木酚,上海源叶生物技术有限公司;二甲基对苯二胺、三羟甲基氨基甲烷,上海麦克林生化科技有限公司;琥珀酸脱氢酶试剂盒、无机磷试剂盒,南京建成生物工程研究所。

1.2 试验仪器设备

HWS-300智能恒温恒湿箱,浙江托普云农科技股份有限公司;X-rite Color i5色差仪,美国Gretag Macbeth公司;Agilent 1260高效液相色谱分析仪,美国安捷伦公司;UV-1800紫外可见分光光度计,日本岛津公司;DDSJ-308A 电导率仪,上海精密科学仪器有限公司。

1.3 试验方法

1.3.1 银条处理

挑选无褐变、无失水、无机械损伤、粗细均匀的银条,采用10 mmol/L草酸溶液(实验确定最佳浓度)处理银条20 min(对照为去离子水处理),晾干表面附着水分后放入塑料筐中(每筐0.5 kg),筐外套0.05 mm聚乙烯薄膜(袋不扎口),在(10±1) ℃、相对湿度85%～90%条件下贮藏30 d。

1.3.2 银条褐变指数(browning index,BI)的测定

参考党东阳等[2]方法对银条褐变程度进行分级。按公式(1)计算银条BI:

(1)

1.3.3 色差L*值的测定

采用色差仪测定银条L*值,每组测定10根银条,每根银条测定3次。

1.3.4 银条呼吸速率的测定

采用静置法测定[17]。取150 g银条放入真空干燥器中,密闭0.5 h后采用0.2 mol/L草酸溶液滴定,计算出银条呼吸速率,结果以mg/(kg·h)表示。

1.3.5 银条丙二醛(malondialdehyde,MDA)和相对电导率的测定

银条MDA含量采用ZHANG等[6]硫代巴比妥酸法测定,银条相对电导率参照LI等[13]方法测定。

1.3.6 银条总酚含量、PPO、过氧化物酶(peroxidase,POD)、苯丙氨酸解氨酶(phenylalnine ammonialyase,PAL)活性的测定

银条总酚含量采用党东阳等Folin-Ciocalteu法测定[2],单位为mg/g FW。银条采用邻苯二酚法测定[2],单位为U/(min·g FW)。银条过氧化物酶(peroxidase,POD)采用TANG等[18]方法测定,单位为U/(min·g FW)。银条苯丙氨酸解氨酶(phenylalnine ammonialyase,PAL)参照谭谊谈等[19]方法测定,单位为U/(h·g FW)。

1.3.7 银条能量物质含量及能荷(energy charge,EC)的测定

采用LI等[13] HPLC测定银条中相关的能量物质含量,单位为μg/g FW。5 g银条鲜样中加入5 mL高氯酸,冰浴研磨后离心,上清液定容至10 mL(pH值调为6.5～6.8),过0.22 μm滤膜备用。HPLC条件为:反向C18分析柱(5 μm×250 mm×4.6 mm),检测波长254 nm,流速0.5 mL/min,进样量20 μL,梯度洗脱(流动相A和B分别为100%甲醇和pH值为7.0 K3PO4缓冲液),0 min,0% A,100% B;10 min,10% A,90% B;14 min,25% A,75% B;15 min,0% A,100% B。按公式(2)计算EC:

(2)

1.3.8 银条能量代谢相关酶活性测定

5 g银条鲜样中加入10 mL 50 mmol/L Tris-HCl低温研磨,离心后沉淀用4 mL洗涤液(10 mmol/L,Tris-HCl,pH值为7.2)溶解,再次离心,沉淀加2 mL洗涤液得银条线粒体粗酶液。银条琥珀酸脱氢酶(succinodehydrogenase,SDH)活性采用试剂盒进行测定,单位为U/(min·g FW)。参照李泽等[20]方法测定银条细胞色素氧化酶(cytochrome oxidase,CCO)活性,单位为U/(min·g FW)。

参照JIN等[21]方法测定银条中H+-ATPPase和Ca2+-ATPase活性。0.1 mL银条线粒体粗酶液加入0.7 mL Tris-HCl(pH值为8.0,30 mmol/L,含3 mmol/L MgSO4、50 mmol/L NaNO3、0.1 mmol/L钒酸钠、50 mmol/L KCl、0.1 mmol/L钼酸铵,测定Ca2+-ATPase时加入3 mmol/L Ca(NO3)2),加0.1 mL 30 mmol/L ATP-Tris(pH值为8.0)启动反应,37 ℃保温20 min,加0.1 mL 550 g/L三氯乙酸终止反应,采用无机磷试剂盒测定生成的无机磷量,计算H+-ATPase和Ca2+-ATPase活性,以每克银条样品每小时释放1 μmol无机磷为1个酶活力单位U,结果以U/(h·g FW)表示。

1.4 数据处理与分析

采用Excel 2021及SPSS 16.0软件对试验数据进行处理及显著性分析,以P<0.05表示差异显著,采用Origin 2021软件进行绘图。

2 结果与分析

2.1 草酸处理对采后银条BI和L*值的影响

对照和草酸处理组银条贮藏30 d后外观情况如图1所示,对照组银条褐变严重(尤其是端部),而草酸处理银条表面的褐变程度较轻,两端没有出现严重的褐变现象。BI能反映采后银条贮藏期间的褐变程度[22]。对照组和草酸处理组银条BI在贮藏15 d后快速上升,银条表面的褐变程度也迅速增加,草酸处理银条BI在贮藏15～30 d期间显著低于对照(P<0.05)(图2-a)。贮藏第30天时,对照组银条BI为草酸处理组的2.11倍,说明草酸处理能有效减轻采后银条褐变的发生,维持其较好贮藏品质。

L*值能反映采后果蔬表面的亮度,是衡量果蔬褐变程度的指标之一[19]。两组银条贮藏15 d后L*值迅速降低,草酸处理明显抑制了贮藏20～30 d内银条L*值的下降(P<0.05)(图2-b)。贮藏第30天时,草酸处理组和对照组银条L*值分别比贮藏第0天时下降了14.49%和19.70%,说明草酸处理对于维持银条外观品质具有较好作用,可明显减轻银条褐变发生。

2.2 草酸处理对银条呼吸速率的影响

呼吸速率是衡量采后果蔬呼吸作用强弱的重要指标[17]。图3显示,两组银条呼吸速率呈先升后略降的趋势,第15天时出现呼吸速率高峰,此时对照组银条呼吸速率为79.69 mg/(kg·h),草酸处理组为65.90 mg/(kg·h),比对照组降低了17.30%,且草酸处理显著抑制了贮藏15～30 d银条呼吸速率(P<0.05),说明草酸处理能减弱银条呼吸作用,延缓银条品质劣变过程。

2.3 草酸处理对银条MDA含量和相对电导率的影响

MDA含量和相对电导率能反映采后果蔬细胞膜损伤程度[6]。由图4可看出,草酸处理组和对照组银条MDA含量和相对电导率在贮藏前15 d变化均较小,贮藏15 d后急剧升高。草酸处理能显著降低贮藏15～30 d银条MDA含量和相对电导率的升高(P<0.05)。贮藏第30天时,对照组银条MDA含量和相对电导率分别比草酸处理组高24.06%和30.09%,说明草酸处理能有效维持银条细胞膜完整性,减轻细胞膜损伤。

2.4 草酸处理对银条总酚含量的影响

采后果蔬中酚类物质含量的高低对于酶促褐变的发生有重要影响[23]。贮藏前15 d两组银条总酚含量变化较小(图5),贮藏15 d后银条总酚含量迅速上升,草酸处理显著抑制了银条中总酚的上升趋势(P<0.05),说明草酸处理可抑制银条贮藏后期总酚物质积累,减少酶促褐变底物的提供,降低银条酶促褐变。

2.5 草酸处理对采后银条PPO、POD和PAL活性的影响

PPO、POD可协同参与采后果蔬酶促褐变反应,PAL作为苯丙烷代谢途径中关键酶,间接参与果蔬酶促褐变反应[11,18-19]。从图6可看出,银条PPO、POD和PAL活性在贮藏期间均不断升高,造成银条褐变程度加剧。草酸处理组PPO、POD、PAL活性在贮藏期间均维持在较低水平,贮藏20～30 d时银条的3个褐变相关酶活性均显著低于对照(P<0.05)。贮藏末期,草酸处理组银条PPO、POD和PAL活性分别比对照降低了32.76%、19.40%和15.20%,说明草酸处理能显著抑制银条褐变相关酶活性,阻碍黑色素的产生与积累,减缓银条苯丙烷代谢速率,降低褐变发生。

2.6 草酸处理对采后银条ATP、ADP、AMP及EC的影响

能量是采后果蔬生命活动的基础,ATP和ADP等物质含量减少及EC水平下降会导致采后果蔬生理代谢失调,加快果蔬品质劣变速度[24]。由图7-a可知,贮藏前15 d银条ATP含量较高,银条褐变程度也较轻;贮藏15 d后,银条ATP含量迅速下降,银条褐变程度也迅速增加,草酸处理显著抑制银条贮藏15～30 d内ATP含量的下降(P<0.05)。对照组银条ADP含量在贮藏10 d后急剧下降,而草酸处理组银条ADP含量在贮藏期间变化幅度较小(图7-b),两者在贮藏15～30 d内差异显著(P<0.05)。草酸处理银条AMP含量始终低于对照(图7-c),贮藏15～30 d期间具有显著性差异(P<0.05)。草酸处理组和对照组银条EC在贮藏前15 d处于较高水平,之后急剧下降(图7-d),草酸处理明显抑制了银条EC的下降(P<0.05),贮藏30 d时,对照组能荷为0.38,草酸处理组EC为0.50,是对照组的1.34倍。综上说明,草酸处理可以维持银条贮藏后期较高的能量物质含量和EC水平,为银条贮藏中的各种生理活动提供充足能量供应。

2.7 草酸处理对采后银条SDH、CCO、H+-ATPase和Ca2+-ATPase活性的影响

采后果蔬体内能量代谢关键酶活性高低与果蔬能量水平密切相关[8]。SDH是三羧酸循环过程关键酶,能反映线粒体膜功能特性[20]。草酸处理组和对照组银条SDH活性在贮藏后期差别较大,草酸处理显著提高了贮藏20～30 d银条SDH活性(P<0.05)(图8-a)。CCO可传递电子通过氧化磷酸化产生能量[20]。对照组和草酸处理组银条CCO活性在第15天时达到高峰,此时草酸处理CCO活性是对照组的1.19倍,贮藏15 d后草酸处理显著抑制了银条CCO活性的下降(P<0.05)(图8-b)。H+-ATPase可维持细胞中质子浓度差,通过产生跨膜质子电化学梯度从而推动ATP合成,Ca2+-ATPase可调节果蔬胞内钙稳态,维持线粒体功能[9]。银条中H+-ATPase和Ca2+-ATPase变化趋势基本一致(图8-c和图8-d),贮藏15 d前维持在较高水平,草酸处理显著抑制贮藏后期银条H+-ATPase和Ca2+-ATPase活性(P<0.05),贮藏第30天,草酸处理组银条H+-ATPase与对照组差异较大,是对照组的1.64倍,说明草酸处理能提高银条H+-ATPase和Ca2+-ATPase活性,促进ATP生成。

2.8 银条BI的相关性分析

由表1可知,银条BI与ATP、ADP、EC、H+-ATPase和Ca2+-ATPase呈极显著负相关(P<0.01),与AMP、总酚、PPO、POD、PAL呈极显著正相关(P<0.01),说明银条褐变受到能量水平及总酚、褐变相关酶活性的影响。银条ATP、ADP、EC均与H+-ATPase和Ca2+-ATPase呈极显著正相关(P<0.01),与SDH和CCO活性呈负相关,但没有达到显著性水平,推测银条H+-ATPase和Ca2+-ATPase活性高低对于银条EC水平的影响较SDH和CCO大。

3 讨论

采后银条贮藏中主要的品质劣变问题之一是发生酶促褐变,采用低温、气调包装等可抑制银条酶促褐变的发生[3]。先前很多研究发现草酸处理能降低荔枝[11]、桃[12]、莴苣[25]等多种果蔬酶促褐变的发生,提高其贮藏品质。本研究也得到了相同的结果,草酸处理能显著抑制贮藏15～30 d期间银条酶促褐变的发生,维持银条较低BI和较高L*值,提高了银条贮藏品质,这与ALI等[14]研究结果一致。

采后果蔬体内酚类物质含量和PPO等相关酶活性的高低会影响果蔬褐变的发生。ZHANG等[23]认为酚类物质含量高的果蔬更容易发生酶促褐变。谭谊谈等[19]研究表明,抑制果蔬PPO、POD和PAL活性会降低褐变的发生。本研究结果显示,贮藏15～30 d期间,草酸处理银条总酚含量、PAL、PPO、POD活性均显著低于对照,相关性分析表明,银条BI与总酚、PPO、POD、PAL呈极显著正相关(r分别为0.926、0.922、0.841、0.811),这表明草酸处理能降低苯丙烷代谢途径关键酶PAL活性,抑制银条酚类物质的积累,减少酶促褐变底物的供应,降低银条褐变的发生;同时银条PPO、POD活性也被草酸抑制,降低了其与酚类的酶促褐变反应,这与先前ZHENG等[26]采用草酸处理竹笋的研究结果类似。本研究结果还显示,在贮藏后期(15～30 d),草酸处理银条MDA含量和相对电导率均显著低于对照,说明草酸处理银条细胞膜损伤程度较对照组低,银条细胞完整性较高,有利于维持银条酚类物质和酚酶的区室化分布,阻碍两者结合而发生酶促褐变,这是草酸处理降低银条褐变的原因之一。郑剑英[27]研究甘薯褐变也有类似结果。

采后果蔬褐变的发生与能量供应密切相关[17],能量供应不足会导致其生理代谢紊乱,加剧褐变发生。WANG等[28]认为,南果梨果皮褐变的发生与ATP含量和能荷水平降低有关。TANG等[18]和王志华等[24]认为果蔬褐变速度的快慢与能量水平有关,提高能量水平能抑制果蔬褐变的发生[22]。本试验结果显示,贮藏15～30 d期间银条ATP和EC快速下降的同时银条BI急剧增加,相关性分析表明银条BI与ATP、ADP、EC呈极显著负相关(r分别为-0.927、-0.807、-0.934),这说明银条褐变的急剧增加可能是由于能量水平快速下降导致的。草酸处理显著提高了银条贮藏15～30 d期间ATP、ADP及EC水平,保证了银条贮藏后期能量供应,较好地保持了银条细胞膜的完整性,减轻了银条酶促褐变的发生,这与草酸处理猕猴桃[29]的研究结果类似。本研究还发现草酸处理能显著抑制银条贮藏15～30 d期间呼吸作用,说明草酸处理能显著抑制银条生理代谢活动,减少银条体内能量消耗,这有利于银条体内ATP、ADP等能量物质积累,这是草酸处理银条能荷水平高于对照的原因之一,黄欣莉等[17]、LI等[30]研究香菇和白蘑菇褐变时也有类似结果。

采后果蔬SDH、CCO、H+-ATPase和Ca2+-ATPase活性下降会导致果蔬线粒体产能效率降低,果蔬能量供应亏缺,引起果蔬褐变发生[21,31-32]。采用茉莉酸甲酯[21]、ClO2[33]、没食子酸丙酯[22]处理能提高桃、龙眼等SDH、CCO、H+-ATPase和Ca2+-ATPase活性,显著降低桃和龙眼褐变程度。本研究结果显示,草酸处理维持了银条贮藏15～30 d较高SDH、CCO、H+-ATPase和Ca2+-ATPase活性,保证了贮藏后期银条能量的产生和供应,使得银条褐变减轻,这与JIN等[12]研究结果一致。相关性分析表明,银条H+-ATPase和Ca2+-ATPase活性与银条BI呈极显著负相关(r分别为-0.974、-0.893),而银条SDH、CCO活性与银条BI没有显著相关性(r分别为0.398、0.213),推测草酸处理提高银条EC水平主要是由于提高了银条H+-ATPase和Ca2+-ATPase活性,保证了银条中Ca2+浓度的稳定及膜上质子跨膜驱动力,维持了银条线粒体产生ATP的能力,这是草酸处理减轻银条褐变的又一原因。

4 结论

综上,银条褐变的发生与能量代谢、总酚以及褐变相关酶活性密切相关,草酸处理降低银条褐变的原因可归结于两个方面:一是草酸提高了银条能量代谢关键酶活性而维持其较高能荷水平,较好地维持了细胞膜的完整性,阻碍了酚类物质与褐变相关酶的结合而降低了褐变的发生;二是草酸处理维持了银条较低的总酚含量及PPO、POD、PAL活性,减少了酚类物质与褐变相关酶的反应,减轻了酶促褐变的发生,保持了银条较低BI和较高L*值,提高了银条贮藏品质。

参考文献

[1] 焦镭, 蒋小锋, 魏楠, 等.银条面包的研制及工艺优化[J].粮食与油脂, 2020, 33(10):46-51.JIAO L, JIANG X F, WEI N, et al.Development and process optimization of Stachys floridana Schuttl.ex Benth bread[J].Cereals &Oils, 2020, 33(10):46-51.

[2] 党东阳, 李佩艳, 刘建学, 等.不同贮藏温度对银条褐变及细胞壁降解的影响[J].食品与发酵工业, 2023, 49(4):88-96.DANG D Y, LI P Y, LIU J X, et al.Effects of different storage temperatures on browning and cell wall degradation of Stachys flordana Schuttl.ex Benth[J].Food and Fermentation Industries, 2023, 49(4):88-96.

[3] 郭香凤, 史国安.低温和气调小包装处理对银条净菜保鲜品质的影响[J].食品科学, 2008, 29(8):612-616.GUO X F, SHI G A.Effects of treatment of low-tempreture combined with modified atmosphere package on fresh-keeping quatlity of minimally processed Stachys floridana schuttl.ex Benth[J].Food Science, 2008, 29(8):612-616.

[4] 王静. 能量亏缺对果蔬采后组织衰老、褐变与病害的影响[J].保鲜与加工, 2020, 20(1):237-242.WANG J.Effects of energy deficiency on tissue senescence, browning and diseases of postharvest fruits and vegetables[J].Storage and Process, 2020, 20(1):237-242.

[5] LIN Y F, LIN Y X, LIN H T, et al.Hydrogen peroxide-induced pericarp browning of harvested Longan fruit in association with energy metabolism[J].Food Chemistry, 2017, 225:31-36.

[6] ZHANG L, WANG J W, ZHOU X, et al.Effect of ATP treatment on enzymes involved in energy and lipid metabolisms accompany peel browning of ‘Nanguo’ pears during shelf life after low temperature storage[J].Scientia Horticulturae, 2018, 240:446-452.

[7] CHEN M Y, LIN H T, ZHANG S, et al.Effects of adenosine triphosphate (ATP) treatment on postharvest physiology, quality and storage behavior of Longan fruit[J].Food and Bioprocess Technology, 2015, 8(5):971-982.

[8] WANG T, HU M J, YUAN D B, et al.Melatonin alleviates pericarp browning in Litchi fruit by regulating membrane lipid and energy metabolisms[J].Postharvest Biology and Technology, 2020, 160:111066.

[9] 蔺凯丽, 黄琦, 黄琦辉, 等.麦角硫因抑制双孢蘑菇褐变及其与能量代谢关系[J].中国农业科学, 2018, 51(8):1568-1576.LIN K L, HUANG Q, HUANG Q H, et al.Browning inhibition and energy metabolism mechanism of Agaricus bisporus by ergothioneine treatment[J].Scientia Agricultura Sinica, 2018, 51(8):1568-1576.

[10] 李佩艳, 尹飞, 苏娇, 等.草酸处理减轻采后果蔬冷害机制研究进展[J].食品与发酵工业, 2022, 48(24):319-326.LI P Y, YIN F, SU J, et al.Research progress on the mechanism of oxalic acid treatment to reduce chilling injury of postharvest fruits and vegetables[J].Food and Fermentation Industries, 2022, 48(24):319-326.

[11] SHAFIQUE M, KHAN A S, MALIK A U, et al.Exogenous application of oxalic acid delays pericarp browning and maintain fruit quality of Litchi cv.“gola”[J].Journal of Food Biochemistry, 2016, 40(2):170-179.

[12] JIN P, ZHU H, WANG L, et al.Oxalic acid alleviates chilling injury in peach fruit by regulating energy metabolism and fatty acid contents[J].Food Chemistry, 2014, 161:87-93.

[13] LI P Y, ZHENG X L, LIU Y, et al.Pre-storage application of oxalic acid alleviates chilling injury in mango fruit by modulating proline metabolism and energy status under chilling stress[J].Food Chemistry, 2014, 142:72-78.

[14] ALI S, KHAN A S, ANJUM M A, et al.Effect of postharvest oxalic acid application on enzymatic browning and quality of Lotus (Nelumbo nuciferaGaertn.) root slices[J].Food Chemistry, 2020, 312:126051.

[15] BIN ARIF A, SUSANTO S, WIDAYANTI S M, et al.Pre-storage oxalic acid treatment inhibits postharvest browning symptoms and maintains quality of abiu (Pouteria caimito) fruit[J].Scientia Horticulturae, 2023, 311:111795.

[16] LI P Y, YIN F, SONG L J, et al.Alleviation of chilling injury in tomato fruit by exogenous application of oxalic acid[J].Food Chemistry, 2016, 202:125-132.

[17] 黄欣莉, 韩延超, 陈杭君, 等.1-甲基环丙烯通过调控香菇能量代谢抑制其采后褐变[J].食品科学, 2022, 43(13):192-198.HUANG X L, HAN Y C, CHEN H J, et al.1-methylcyclopropene inhibits postharvest browning of Lentinus edodes by regulating energy metabolism[J].Food Science, 2022, 43(13):192-198.

[18] TANG R F, ZHOU Y J, CHEN Z, et al.Regulation of browning and senescence of Litchi fruit mediated by phenolics and energy status:A postharvest comparison on three different cultivars[J].Postharvest Biology and Technology, 2020, 168:111280.

[19] 谭谊谈, 曾凯芳.1-MCP处理对鲜切芋艿褐变的影响[J].食品科学, 2014, 35(2):305-309.TAN Y T, ZENG K F.Effect of 1-MCP treatment on browning of fresh-cut taro[J].Food Science, 2014, 35(2):305-309.

[20] 李泽, 黄和, 钟赛意, 等.减压处理对荔枝果实膜脂代谢和能量代谢的影响[J].食品与发酵工业, 2021, 47(16):159-165.LI Z, HUANG H, ZHONG S Y, et al.Effects of hypobaric treatment on membrane lipid and energy metabolism of Litchi fruit[J].Food and Fermentation Industries, 2021, 47(16):159-165.

[21] JIN P, ZHU H, WANG J, et al.Effect of methyl jasmonate on energy metabolism in peach fruit during chilling stress[J].Journal of the Science of Food and Agriculture, 2013, 93(8):1827-1832.

[22] LIN Y F, HU Y H, LIN H T, et al.Inhibitory effects of propyl gallate on tyrosinase and its application in controlling pericarp browning of harvested Longan fruits[J].Journal of Agricultural and Food Chemistry, 2013, 61(11):2889-2895.

[23] ZHANG Q, LIU Y L, HE C C, et al.Postharvest exogenous application of abscisic acid reduces internal browning in pineapple[J].Journal of Agricultural and Food Chemistry, 2015, 63(22):5313-5320.

[24] 王志华, 贾朝爽, 王文辉, 等.低温贮藏对‘金红’苹果能量代谢和品质的影响[J].园艺学报, 2020, 47(12):2277-2289.WANG Z H, JIA C S, WANG W H, et al.Effects of low temperature storage on energy metabolism, related physiology and quality in ‘Jinhong’ apple fruit[J].Acta Horticulturae Sinica, 2020, 47(12):2277-2289.

[25] PACE B, CAPOTORTO I, PALUMBO M, et al.Combined effect of dipping in oxalic or in citric acid and low O2 modified atmosphere, to preserve the quality of fresh-cut lettuce during storage[J].Foods, 2020, 9(8):988.

[26] ZHENG J, LI S G, XU Y H, et al.Effect of oxalic acid on edible quality of bamboo shoots (Phyllostachys prominens) without sheaths during cold storage[J].LWT, 2019, 109:194-200.

[27] 郑剑英. 不同处理对低温下甘薯糖代谢、能量代谢和酚类代谢的调控研究[D].杭州:浙江农林大学, 2015.ZHENG J Y.Physiological and biochemical changes in fresh-cut bamboo shoots (Phyllostachy pubescens) during preservation[D].Hangzhou:Zhejiang Agriculture and Forestry University, 2015.

[28] WANG J W, ZHOU X, ZHOU Q, et al.Low temperature conditioning alleviates peel browning by modulating energy and lipid metabolisms of ‘Nanguo’ pears during shelf life after cold storage[J].Postharvest Biology and Technology, 2017, 131:10-15.

[29] 梁春强, 吕茳, 靳蜜静, 等.草酸处理对采后猕猴桃冷害、抗氧化能力及能荷的影响[J].园艺学报, 2017, 44(2):279-287.LIANG C Q, LYU J, JIN M J, et al.Effects of oxalic acid treatment on chilling injury, antioxidant capacity and energy status in harvested kiwifruits under low temperature stress[J].Acta Horticulturae Sinica, 2017, 44(2):279-287.

[30] LI L, KITAZAWA H, ZHANG X H, et al.Melatonin retards senescence via regulation of the electron leakage of postharvest white mushroom (Agaricus bisporus)[J].Food Chemistry, 2021, 340:127833.

[31] LIU G S, ZHANG Y X, YUN Z, et al.Melatonin enhances cold tolerance by regulating energy and proline metabolism in Litchi fruit[J].Foods, 2020, 9(4):454.

[32] LI D, LIMWACHIRANON J, LI L, et al.Involvement of energy metabolism to chilling tolerance induced by hydrogen sulfide in cold-stored banana fruit[J].Food Chemistry, 2016, 208:272-278.

[33] VICHAIYA T, UTHAIBUTRA J, SAENGNIL K.Gaseous chlorine dioxide increases energy status and energy metabolism-related enzyme activities leading to reduction in pericarp browning of Longan fruit during storage[J].Scientia Horticulturae, 2020, 263:109118.

Effects of oxalic acid treatment on browning and energy metabolism of postharvest Stachys flordana Schuttl.ex Benth

LI Peiyan1,2,3*, SU Jiao1, XIAO Xinxin1, LUO Denglin1,2,3, HAN Sihai1,2,3

1(College of Food and Bioengineering, Henan University of Science and Technology, Luoyang 471023, China)
2(Henan Engineering Research Center of Food Material, Luoyang 471023, China)3(National Experimental Teaching Demonstration Center of Food Processing and Security, Luoyang 471023, China)

ABSTRACT To investigate the control effect of oxalic acid treatment on browning of postharvest Stachys flordana Schuttl.ex Benth and to explore the relationship between browning and energy metabolism, Stachys flordana Schuttl.ex Benth was dipped in 10 mmol/L oxalic acid solution for 20 min, and then stored at 10 ℃ for 30 days.The related indexes of browning and energy metabolism of Stachys flordana Schuttl.ex Benth were measured, which was used to analyze the effect of oxalic acid treatment on browning and reveal the relationship between browning and energy metabolism.Results showed that, compared with the control, oxalic acid treatment could effectively inhibit the increase of the browning index and the decrease of the L* value, which showed a significant difference during 15-30 days of storage.Oxalic acid treatment remarkably reduced the increase of respiration, inhibited the increase of malondialdehyde (MDA) and relative conductivity, and better maintained the integrity of the cell membrane of Stachys flordana Schuttl.ex Benth.The activities of polyphenol oxidase (PPO), peroxidase (POD), and phenylalanine aminolyase (PAL) were reduced, and total phenolic content was also significantly decreased, which could reduce the browning of Stachys flordana Schuttl.ex Benth.Meanwhile, oxalic acid treatment could improve the activities of succinate dehydrogenase (SDH), cytochrome oxidase (CCO), H+-ATPase, and Ca2+-ATPase, inhibit the decrease of ATP, ADP, and energy charge (EC), and maintain a high energy level in late storage of Stachys flordana Schuttl.ex Benth, which could delay the browning of Stachys flordana Schuttl.ex Benth.Correlation analysis showed that the browning index of Stachys flordana Schuttl.ex Benth was negatively correlated with ATP, ADP, EC, H+-ATPase, and Ca2+-ATPase, while positively correlated with total phenolic, PPO, POD, PAL, and AMP content.In conclusion, the inhibition of oxalic acid treatment on the browning of Stachys flordana Schuttl.ex Benth was related to the improvement of energy metabolism and energy levels, as well as the reduction of total phenolic content and the activity of enzymes related to browning.

Key words oxalic acid;Stachys flordana Schuttl.ex Benth;browning;energy metabolism

DOI：10.13995/j.cnki.11-1802/ts.038404

引用格式：李佩艳,苏娇,肖鑫鑫,等.草酸处理对采后银条褐变及能量代谢的影响[J].食品与发酵工业,2025,51(3):257-264.LI Peiyan, SU Jiao, XIAO Xinxin, et al.Effects of oxalic acid treatment on browning and energy metabolism of postharvest Stachys flordana Schuttl.ex Benth[J].Food and Fermentation Industries,2025,51(3):257-264.

第一作者：博士,副教授(通信作者,E-mail:lipeiyan77@163.com)

基金项目：国家自然科学基金项目(31701665);河南省重大公益专项(201300110300)

收稿日期：2023-12-28,改回日期:2024-03-19