超声波协同钙浸渍对冬枣品质特性的影响

探究超声波协同钙浸渍处理对采后冬枣品质特性[硬度、可溶性固形物(soluble solids content,SSC)、可滴定酸(titratable acid,TA)、失重率]、果胶含量[水溶性果胶(water soluble pectin,WSP)、螯合性果胶(chelating soluble pectin,CSP)、碱溶性果胶(sodium carbonate-soluble pectin,SSP)]及酶活性[多聚半乳糖醛酸酶(polygalacturonic acid,PG)、果胶甲酯酶(pectin methylesterase,PME)]。结果表明,超声波协同钙浸渍处理能够显著抑制冬枣果实冷藏过程中硬度、SSC和TA含量的降低,减小果实失重率并抑制PG和PME的酶活性,提高采后冬枣贮藏期间品质特性,并延缓其果实细胞壁多糖的降解,可作为采后冬枣保鲜的有效手段。     

氯化钙处理对采后百香果细胞壁物质代谢的影响

为探究氯化钙（CaCl2）处理对常温贮藏百香果细胞壁物质代谢的影响,采用5% CaCl2 对新鲜采摘的百香果进行浸泡处理5 min,清水处理为对照,于（22±1）℃条件下贮藏8 d,定期测定果实硬度、色差、细胞壁组分及细胞壁代谢相关酶活性,并进行相关性分析和主成分分析。结果表明,5% CaCl2 处理能够控制采后百香果硬度、色泽的下降,抑制共价结合型果胶（covalently bound pectin,SCSP）、紧密型半纤维素（24KSF）的降解,降低水溶性果胶（water soluble pectin,WSP）、离子型果胶（ionic bound pectin,ISP）、松散型半纤维素（4KSF）的含量,延缓多聚半乳糖醛酸酶（polygalacturonase,PG）、果胶甲酯酶（pectin methylesterase,PME）活性的上升。相关性分析结果说明,果实硬度与色泽、WSP含量、ISP 含量、24KSF 含量、PG 活性、PME 活性极显著相关（P<0.01）。主成分分析结果表明,PC1、PC2、PC3 代表了12 个指标82.266%的信息,能综合反映百香果生理指标的大部分信息,且CaCl2 处理组综合得分始终高于对照组,说明氯化钙处理可通过调节细胞壁物质代谢来减缓百香果的软化速度,延长货架期。     

3种常用剁椒加工品种的质构品质及果胶特性

以目前3种最常用的剁椒加工品种“艳红”“天宇”和“金塔”为原料,对其质构品质和果胶特性进行研究。结果表明:同“艳红”和“天宇”相比,“金塔”在果长、果重、含水率以及表面微观结构等方面均存在差异,其果实大,含水率高,细胞组织结构排列稀疏。此外,“金塔”硬度、黏力和黏性均为最高,与“艳红”和“天宇”间存在显著差异(P < 0.05)。对于果胶特性,“金塔”的水溶性果胶(WSP)和碱溶性果胶(SSP)含量最高,且WSP分子质量也较高,而螯合性果胶(CSP)含量、CSP和SSP分子质量则较低。“金塔”WSP鼠李糖、CSP和SSP阿拉伯糖含量显著高于“艳红”和“天宇”(P < 0.05),CSP鼠李糖含量低于“艳红”和“天宇”,SSP鼠李糖和WSP阿拉伯糖含量低于“天宇”而高于“艳红”。相关性分析表明,辣椒硬度与WSP含量、SSP含量和WSP分子质量间均呈极显著正相关(P < 0.01)。总之,相比于“艳红”和“天宇”,“金塔”具有较高的WSP含量,而其CSP含量、CSP和SSP分子质量较低,细胞结构不稳定,在加工及贮藏过程中易发生水分散失和果胶降解,引起果实软化。相比于“金塔”,“艳红”和“天宇”可能更有利于维持剁椒产品的质构品质。     

1-甲基环丙烯对采后南果梨果实软化的影响

以南果梨果实为材料,研究1 μL/L 1-甲基环丙烯（1-methylcyclopropene,1-MCP）处理对其采后常温 （23±1）℃贮藏过程中软化的影响。结果表明：与对照组相比,1-MCP处理能推迟乙烯高峰的出现并降低其峰 值,减缓果实硬度的下降与丙二醛含量的上升,有效抑制纤维素酶、多聚半乳糖醛酸酶、果胶甲酯酶及淀粉酶活力 的增加,减缓可溶性果胶质量分数的增加,同时延缓纤维素、原果胶及淀粉质量分数的下降。因此,1-MCP处理能 有效减缓采后南果梨果实的软化进程,延长其贮藏时间。     

1-MCP处理结合冰温贮藏对磨盘柿果实软化衰老的影响

目的：探讨冷藏、冰温贮藏、1-甲基环丙烯（1-methylcyclopropene,1-MCP）处理结合冰温贮藏对采后柿果硬度和软化相关物质代谢的影响。结果：与冷藏处理相比,冰温贮藏有效抑制了乙烯生成,抑制了多聚半乳糖醛酸酶（PG）、纤维素酶（Cx）、淀粉酶活性的增加,抑制了可溶性果胶含量的升高,延缓了果肉硬度的降低,而1-MCP处理结合冰温贮藏对柿果实硬度的保持、抑制PG、Cx、淀粉酶活性升高的作用好于冰温单一贮藏,因此,1-MCP处理结合冰温贮藏是保持柿果实硬度较为适宜的贮藏方法。     

李子采后软化过程中细胞壁酶活性对果胶降解的影响

以半边红李子为实验材料,利用质构分析仪研究其常温贮藏软化过程,并考察主要细胞壁酶(果胶酯酶PE、外切多聚半乳糖醛酸酶exo-PG、内切多聚半乳糖醛酸酶endo-PG和葡聚糖苷酶EG)活性变化对果实软化及原果胶降解为可溶性果胶(WSP、ASP、HSP、SSP)的影响。结果表明,李子常温贮藏过程中PE活性变化较小,exo-PG活性一直不断下降,endo-PG活性不断升高,EG活性贮藏前期略有下降,8d之后开始不断升高。李子果肉硬度和粘性降低与原果胶和SSP降解关系密切,ASP降解与粘度降低极显著相关(p0.01),HSP降解与果肉硬度下降显著相关(p0.05)。果肉硬度和粘度变化与exo-PG活性极显著(p0.01)和显著(p0.05)相关。endo-PG活性变化对果肉硬度下降影响比较明显(p0.05)。PE活性变化与原果胶、ASP、HSP、WSP含量变化均显著相关(p0.05);exo-PG活性变化与原果胶、HSP含量变化极显著相关(p0.01),与SSP、WSP含量变化显著相关(p0.05);endo-PG对原果胶和HSP的降解影响比较大(p0.05)。EG对果胶降解影响较小。     

1-甲基环丙烯对硬溶质型桃果实细胞壁多糖降解特性的影响

以硬溶质型桃"晚湖景"为试材,20℃下用1μL/L 1-甲基环丙烯(1-MCP)密闭处理24h,研究1-MCP处理对细胞壁降解过程中多糖组分变化、单糖解离特性以及细胞壁多糖降解相关酶的影响。结果表明:1-MCP处理可以明显抑制硬溶质型桃果实硬度的下降,降低乙烯释放量。1-MCP处理的硬溶质型桃果实中CDTA-2、Na2CO3、KOH和CWM-残渣组分在贮藏过程中下降速率都明显低于未处理果。1-MCP处理能延缓CDTA溶性果胶多糖的解离。同时还抑制了Na2CO3溶性果胶多糖中半乳糖醛酸和鼠李糖构成的主链和阿拉伯糖、半乳糖支链的降解,对半纤维素和纤维素多糖成分降解有一定程度的抑制作用。1-MCP处理可能通过抑制参与细胞壁多糖降解相关酶的活性,从而抑制硬溶质型桃果实细胞壁多糖降解及单糖解离,达到延缓果实软化的目的。     

不同品种枣果中果胶含量、中性单糖组成及分子质量分布

以我国6种枣果为原料,采用柱前衍生结合气-质联用测定6种枣果中3种类型果胶的含量、中性单糖组成,同时采用高效凝胶渗透色谱测定3种类型果胶的分子质量分布。结果表明:6种枣果中均以水溶性果胶(WSP)含量最高,溶于Na_2CO_3型果胶(SSP)次之,螯合性果胶(CSP)含量最低;WSP、CSP和SSP中性单糖受枣果来源不同影响,其中WSP和SSP主要中性单糖为阿拉伯糖、鼠李糖、半乳糖和葡萄糖;而CSP的主要中性单糖为阿拉伯糖、葡萄糖和岩藻糖。果胶的分子质量分布受枣果品种来源和果胶类型两方面影响,其中"金丝小枣"与"木枣"WSP的分子质量分布明显宽于其余4个品种枣果WSP的分子质量分布;"金丝小枣"和"灰枣"中CSP分子质量分布比其余4个品种枣果的分子质量分布更加集中,而且主要集中在高分子端。     

氯化钙与1-甲基环丙烯对伽师瓜果实软化与果胶酶活性及其基因表达影响

筛选抑制伽师瓜果实后熟的最佳氯化钙与1-甲基环丙烯(1-methylcyclopropene,1-MCP)处理浓度,分析其在贮藏过程中呼吸速率、乙烯释放量、果实硬度、果肉质构特性、果胶水解酶(多聚半乳糖醛酸酶PG、果胶甲酯酶PME和果胶酸裂解酶PL)活力及相关基因表达。结果表明,氯化钙,1-MCP均能降低果实的呼吸速率与乙烯释放量,并能推迟与抑制它们的跃变现象。果实硬度与原果胶含量呈正相关,与可溶性果胶含量呈负相关。对照组原果胶含量较处理组低,可溶性果胶含量较处理组高; PG、PME和PL酶活性及其基因表达量呈正向协同,对照组3种酶的活性与酶基因表达量均出现跃变峰,处理组则变化缓慢。氯化钙与1-MCP联合使用能更强更稳定地抑制果实的呼吸强度、乙烯释放量及原果胶水解,更好地延缓果实的软化。     

不同干燥方式对苹果片质构的影响及其与果胶性质的关系

为明确不同干燥方式对苹果片微观结构及果胶的影响,探讨干燥苹果片质构与果胶性质的关系,采用热风干燥（hot air drying,AD）、压差闪蒸干燥（instant controlled pressure drop drying,DIC）、真空冷冻干燥（freeze drying,FD）等技术处理原料,分析脱水苹果片硬脆度和微观结构,以及果胶含量、酯化度和中性糖等性质的变化。结果表明：DIC苹果片脆度最大,并有较好的均匀蜂窝状结构;与未处理鲜样相比,干燥处理后的苹果片水溶性果胶（water-solute pectin,WSP）含量和分子的线性度下降,螯合性果胶（CDTA-solute pectin,CSP）含量和分子的线性度上升,且WSP含量和线性度随着热风干燥温度的上升而下降,CSP具有相反的趋势;AD 90 ℃和DIC获得的脱水苹果片的CSP酯化度最小,分别为24.9±1.2%和23.3±0.4%。综合分析,WSP含量影响脱水苹果片硬度和干燥过程中多孔结构的形成,而酯化度则是影响脱水苹果片脆度的重要因素之一。     

Quality attributes and cell wall properties of strawberries (Fragaria annanassa Duch.) under calcium chloride treatment

Effects of CaCl₂ (0%, 1% and 4%) treatment on quality attributes and cell wall pectins of strawberry fruits stored at 4 °C for 15 d were investigated. Strawberry firmness was not significantly affected by CaCl₂ treatment. Compared to the other groups, the 1% CaCl₂ group had better quality attributes, including decay rate, weight loss and soluble solids content. The treatment with 4% CaCl₂ inhibited weight loss but caused phytotoxicity. During storage, the chain widths and lengths of water-soluble pectin (WSP), chelate-soluble pectin (CSP) and sodium carbonate-soluble pectin (SSP) decreased. Strawberry softening seemed to be due to modifications of CSP and SSP, especially the side chains. CaCl₂ treatment significantly slowed the breakdown of CSP and SSP chains by strengthening the ionic crosslinkages among these pectin molecules. These results illustrate the fundamental CaCl₂ effects and will help improve the application of CaCl₂ to postharvest fruits.     

Changes in texture qualities and pectin characteristics of fermented minced pepper during natural and inoculated fermentation process

Texture qualities and pectin characteristics in fermented minced pepper (FMP) prepared by natural fermentation (NF) and inoculated fermentation (IF) were analysed during fermentation. The results showed variation in texture qualities and pectin characteristics was similar during NF and IF process. The hardness, cell wall material, sodium carbonate-soluble pectin (SSP) and chelate-soluble pectin (CSP) content, and CSP esterification degree decreased, while water-soluble pectin (WSP) content significantly (P < 0.05) increased after fermentation. The rhamnose (Rha) molar ratio in three pectins increased, but arabinose (Ara) and galactose (Gal) molar ratios in most pectins decreased after fermentation. Changes in Ara/Gal and (Gal + Ara)/Rha ratios represented the backbone and branched chains of rhamnogalacturonan-I in three pectins depolymerised during fermentation. The decrease of molecular weight (M_w) in CSP was more obvious than that in WSP and SSP, and it was extensively depolymerised into low-M_w pectin after fermentation. Pearson's correlation analysis showed FMP hardness was extremely (P < 0.01) positively correlated with CSP content and significantly (P < 0.05) positively correlated with SSP content and CSP M_w. Hence, CSP was the main pectin to affect texture compared with WSP and SSP, and its characteristics played a crucial role for regulating FMP texture during NF and IF process.     

1-MCP处理对“岳帅”苹果冷藏软化及相关生理指标的影响

研究1-甲基环丙烯(1-methylcyclopropene,1-MCP)处理对"岳帅"苹果低温贮藏期间与软化相关的主要物质含量及酶活性的影响,探讨1-MCP处理对"岳帅"苹果果实软化的调控机理,为"岳帅"苹果贮藏保鲜提供理论依据。以"岳帅"苹果为研究对象,使用0.0、0.5、1.0、2.0μL/L的1-MCP处理后,于(0.0±0.5)℃、相对湿度90%~95%的冷库内贮藏,定期测定果实硬度、呼吸强度、乙烯释放量、细胞壁组成成分及相关酶活性。"岳帅"苹果采后呼吸强度和乙烯释放量均于第30天时达到峰值,多聚半乳糖醛酸酶(polygalacturonase,PG)也在第30天达活力高峰,果胶甲酯酶、纤维素酶(cellulose,Cx)、β-葡萄糖苷酶第45天达活力高峰,同时果实可溶性果胶含量迅速上升,原果胶、纤维素含量不断下降。0.5μL/L 1-MCP处理可推迟果实呼吸强度高峰、乙烯释放量高峰、PG和Cx活力高峰的出现,对抑制可溶性果胶含量升高和原果胶含量的降低作用显著(P0.05),但对冷藏结束时果实硬度的降低抑制效果不显著(P0.05);1.0μL/L和2.0μL/L 1-MCP处理对果实呼吸强度、乙烯释放量、细胞壁降解酶、可溶性果胶含量均有显著抑制作用(P0.05),并且能显著抑制果实硬度下降(P0.05)。"岳帅"苹果在冷藏期间原果胶、纤维素不断被分解,可溶性果胶不断生成,果实硬度迅速下降;除PG外,各细胞壁降解酶活力高峰均出现在呼吸强度和乙烯释放量高峰之后。1-MCP处理通过改变"岳帅"苹果呼吸强度和乙烯释放量,抑制果实细胞壁降解酶活性并推迟活性高峰,从而减缓果实细胞壁组成成分降解,抑制果实软化。1.0μL/L和2.0μL/L的1-MCP处理效果较为显著。     

CaCl_2对采后不同成熟度冬枣抗氧化及细胞壁代谢的影响

为探讨CaCl_2处理对不同成熟度冬枣(Zizyphus Jujuba Mill.cv.Dongzao)抗氧化能力及细胞壁代谢的影响,试验采用1%和2%CaCl_2浸泡处理白熟期(WM)和半红期(HM)冬枣果实,以水处理为对照,测定20±2℃贮藏过程中果实硬度、过氧化氢(H_2O_2)、丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化物酶(CAT)、抗坏血酸(As A)、还原型谷胱甘肽(GSH)、多聚半乳糖醛酸酶(PG)以及细胞壁组分(水溶性果胶(WSP)、离子结合果胶(ISP)和共价结合果胶(CSP))变化。结果表明,在贮藏过程中1%和2%CaCl_2处理可显著延缓WM和HM期果实硬度下降,抑制H_2O_2和MDA积累,维持较高水平的SOD和CAT活性以及As A和GSH含量,同时,降低PG活性以及WSP和ISP含量,增加CSP含量,其中1%CaCl_2处理对HM期果实作用效果最显著,通过提高其抗氧化活性和抑制细胞壁降解过程,使其在贮藏期间保持较好的果实品质。     

不同处理对生鲜电商模式下“徐香”猕猴桃常温品质变化的影响

生鲜电商模式下,产品直接由冷库递送给消费者,传统的货架期概念转变为常温食用期。为探究该模式下"徐香"猕猴桃常温品质变化规律,确定适宜的贮藏及流通处理方式,首先通过感官评价和仪器测定,确定"徐香"猕猴桃的可食用硬度范围,进而研究1-MCP及不同包装处理对低温贮藏不同阶段果实常温食用品质影响,研究不同初始硬度果实食用期限。结果表明,"徐香"猕猴桃的可食用的硬度范围约为2.6~10.5 N,最佳的食用硬度范围为5.0~7.6 N;1-MCP可显著抑制猕猴桃软化,延长食用期,但不适于短期贮藏果实;纸箱加保鲜袋包装是常温食用期间最为适宜的包装方式,该包装方式均可显著延长短期低温贮藏及1-MCP处理长期贮藏果实的可食用期限及最佳可食用期限。常温食用期间,初始硬度不同果实可实现梯度软化,经不同时间达到可食用期和最佳可食用期,可满足消费者消费期内不同时段的食用要求。     

PECTIC SUBSTANCES AND FIRMNESS OF CUCUMBER PICKLES AS INFLUENCED BY CACL2, NACL AND BRINE STORAGE1

The effects of brine treatments (CaCl₂ and NaCl) and storage on pectic substances and texture of cucumber pickles were examined. Firmness of cucumber pickles was closely associated with the solubility characteristics and degree of esterification (DE) of pectic substances. Brining, storage, time of CaCl₂ addition and concentration of NaCl and CaCl₂ were all observed to influence the characteristics of pectic substances. Important to preventing softening was maintenance of pectic substances not extractable (NXP) by conventional methods, i.e., by water (WSP), the chelator sodium hex-ametaphosphate (CSP), and dilute alkali (OHSP). Erosion of NXP consistently resulted in increased levels of CSP and reduced firmness. Reducing the amount of demethylation of pectins was also associated with maintaining firmness. Although the DE declined rapidly during brining, tissues from treatments that enhanced firmness had pectic substances with the highest DE. CaCl₂ added to brine at the beginning of fermentation was most effective in preventing the demethylation of pectins and solubilization of NXP. In contrast, delayed addition of CaCl₂ and storage in low NaCl concentration (5% or less) caused greater pectin demethylation, erosion of NXP with concomitant increases in CSP and tissue softening.     

Effect of 1-methylcyclopropene on ripening of postharvest persimmon (Diospyros kaki L.) fruit

Postharvest persimmon fruit (Diospyros kaki L. cv. Qiandaowuhe) was stored at 20 °C after being exposed to 3 μl l⁻¹ 1-methylcyclopropene (1-MCP) for 6 h or not (control). Several parameters (firmness, respiration and ethylene production, pectic substances and cell wall hydrolysis enzymes activities) were examined to determine the efficacy of 1-MCP treatment in delaying persimmon fruit ripening. Results showed that ‘Qiandaowuhe’ persimmon fruit displayed a typical climacteric pattern of respiration and ethylene production. Peak CO₂ production and ethylene production was observed on the fourth day. Fruit softening was accompanied by a progressive increase in water-soluble pectic substances (WSP) and a progressive decrease in chelator-soluble pectic substances (CSP) and alkali-soluble pectic substances (ASP). The activities of pectinmethylesterase (PME) and polygalacturonase (PG) started increasing sharply and reached a maximal value on days 4 and 6, respectively, and then decreased slowly. 1-MCP treatment delayed the onset of climacteric ethylene production and respiration in persimmon fruit, and also significantly retarded the activities of PME and PG during ripening at 20 °C. Consistent with the activity trends of cell wall hydrolysis enzymes, 1-MCP treatment also delayed the depolymerization of CSP and ASP and reduced the increase of WSP compared with the control fruit. Thus, application of 1-MCP can greatly extend the postharvest life of ‘Qiandaowuhe’ persimmon fruit.