高静压对黄桃质构相关组分模拟体系的影响

以黄桃质构相关组分(细胞壁物质)为模拟体系,探究了高静压处理、热处理以及贮藏过程对细胞壁物质持水性及其果胶各组分和纤维素含量变化的影响。结果表明:与热处理相比,高静压处理对细胞壁物质的持水性、果胶各组分含量和纤维素含量均无显著影响。与常温贮藏相比,低温贮藏对高静压处理及热处理的细胞壁物质的持水性、各果胶组分含量和纤维素含量无显著影响。相关性分析显示:碱溶性果胶与水溶性果胶之间,碱溶性果胶、水溶性果胶与持水性之间相关性较高。     

灵武长枣贮藏过程中细胞壁降解及多糖结构的变化

研究灵武长枣在4 ℃贮藏25 d过程中,硬度等宏观参数以及细胞壁组分含量及细胞壁结构的变化。结合傅里叶红外光谱技术分析细胞壁果胶多糖中二级结构变化对果胶组分及细胞壁结构的影响。结果表明:采后贮藏25 d内,随贮藏时间的延长,果实硬度不断下降,到贮藏末期硬度为贮藏初期的84.77%。可溶性固形物含量呈“倒V”趋势,贮藏第7天含量达到最高值(27.07%)。提取的果胶组分中,水溶性果胶含量不断上升,相关性分析表明,硬度与可溶性固形物、水溶性果胶呈极显著相关,相关系数分别为0.9638,-0.8862。傅里叶红外光谱分析表明,随着贮藏时间的延长,果胶酯化度降低,果胶中吡喃糖苷键的波峰发生偏移,该变化与枣果软化有关。扫描电镜结果表明,长枣细胞壁结构随贮藏期间的延长,从紧密的蜂窝状结构到松散的有空隙结构,这与果胶组分中水溶性果胶的生成密切相关,这一改变导致枣果硬度下降,表现为枣果发生软化。     

麻竹笋罐头贮藏过程中质构、果胶和色泽的变化

以麻竹笋为实验原料,研究麻竹笋罐头在常温（25 ℃）和低温（4 ℃）贮藏过程中质构、果胶和色泽的变化,并探讨麻竹笋罐头的硬度与果胶变化的相关性。结果表明：麻竹笋罐头在贮藏过程中硬度、原果胶和水溶性果胶含量逐渐下降,贮藏120 d后,常温贮藏和低温贮藏条件下麻竹笋的硬度分别下降39.5%和27.1%,原果胶含量分别下降66.4%和62.8%,水溶性果胶含量分别下降68.1%和75.7%。各果胶组分与硬度之间呈现较好的相关性,而原果胶与硬度之间的相关性高于水溶性果胶与硬度之间的相关性。麻竹笋罐头贮藏过程中亮度值L*和红绿值a*逐渐减小,黄蓝值b*逐渐增加;常温和低温分别贮藏30 d和70 d时,总色差ΔE＞2。     

超高压升压和贮藏期胡萝卜软化特征及其机制

目的:明确升压阶段及超高压处理后贮藏期内果蔬质构的动态变化规律。方法:本文研究100～600 MPa、0～2 min高压处理对胡萝卜硬度的影响,并探究其在14 d贮藏期内的硬度变化。从细胞膜透性、细胞显微结构、细胞壁果胶的酶促降解与组分变化,探究硬度变化的机理。结果:压力大于200 MPa会引起胡萝卜硬度下降(P0.05),300 MPa时硬度仅剩37.7%。保压阶段和贮藏过程中硬度变化不明显。相对电导率随压力的升高而增加,表明细胞膜透性增加。用透射电镜观察胡萝卜的微观结构,结果表明,高压处理能引起细胞形变,400 MPa导致膜裂解,600 MPa导致部分细胞溃散。超高压处理后胡萝卜在4℃贮藏期内,细胞分离和细胞壁降解程度加深。果胶甲酯酶、聚半乳糖醛酸酶仍保持较高活性,水溶性果胶含量显著下降(P0.05),向螯合性、碱溶性果胶的转化加速。结论:超高压引起的胡萝卜硬度损失主要由高压对细胞膜的机械损伤引起,果胶组分的转化有利于贮藏期内硬度的保持。     

超声处理对葡萄细胞壁果胶组分的影响

为明确超声处理下葡萄细胞壁中不同果胶组分含量及结构变化，本研究采用不同超声时间和超声功率对葡萄进行处理，通过咔唑硫酸法、PMP柱前衍生化法、高效液相凝胶色谱分析、扫描电子显微镜、傅里叶变换红外光谱分析和圆二色谱分析等手段分析了葡萄细胞壁中果胶组分含量、单糖组成及结构变化。结果表明，新鲜葡萄细胞壁果胶中碱溶性果胶含量最高，为27.41 mg/g AIR，螯合型果胶含量最低，为8.25 mg/g AIR；不同超声处理后总果胶含量呈下降趋势，其中水溶性果胶含量增加，螯合型和碱溶性果胶含量降低。果胶单糖共检测到6种，不同果胶组分单糖组成不同，水溶性果胶中半乳糖和阿拉伯糖含量较高，螯合型果胶中葡萄糖醛酸含量最多，而碱溶性果胶中含量最高的为鼠李糖；超声处理后果胶组分单糖组成不变，但含量均发生降低；超声作用未改变果胶主链结构，但其线性结构和支链程度均发生变化。随着超声处理时间和功率的增加，不同果胶的分子量整体均呈下降趋势，并且在微观结构上呈现更加松散形态。此外，超声作用对果胶组分特征官能团影响较小，但对螯合型果胶和碱溶性果胶分子的结构和链构象产生作用，使其最大响应值发生移动，并且超声功率作用影响更大...     

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。     

热激处理减轻黄瓜冷害与细胞壁代谢的关系

为了进一步阐明热激处理缓解黄瓜冷害症状的作用机理,研究热激处理对采后黄瓜果实冷害指数、细胞壁组分以及细胞壁降解酶活性的影响,将"金田208"黄瓜经42℃热水处理10 min后,于(2±1)℃下贮藏。贮藏期间定期测定黄瓜果实的冷害指数、果实硬度、细胞壁组分含量和细胞壁水解酶活性。实验结果表明:与对照组相比,热激处理可以显著(p0.05)降低黄瓜果实受到低温胁迫时的冷害指数,能够降低果胶甲酯酶(PME)、多聚半乳糖醛酸酶(PG)、β-葡萄糖苷酶和纤维素酶的活性,能够延缓果胶和纤维素含量的下降。相关性分析结果表明,黄瓜的冷害与细胞壁组分(原果胶、可溶性果胶、纤维素)之间存在极显著(p0.01)的相关性,与细胞壁水解酶PME和纤维素酶活性之间存在极显著(p0.01)的相关关系,因此可以认为热激处理可以通过降低采后黄瓜果实细胞壁降解酶的活性而减少细胞壁组分的降解,从而维持细胞壁结构的完整性,使黄瓜果实表现出一定的抗冷性。     

嘎拉苹果果实质地发育软化与细胞壁降解及其基因表达的关系

以嘎拉苹果为试材,分析了果实发育软化过程细胞壁组分、细胞壁酶活性及其酶基因表达的变化。结果表明,发育期,细胞壁物质(CWM)及其组分均先升后降,果胶中共价结合果胶(CSP)含量最高,纤维素含量远高于半纤维素,此期CSP和纤维素含量与硬度显著相关,细胞壁酶表现不同的活性变化和基因表达,并与细胞壁组分存在一定相关性,表明细胞壁降解参与了果实发育期的相关生理过程。采后CSP含量快速降低,水溶性果胶(WSP)含量开始增加,纤维素和半纤维素含量降低,均与硬度显著或极显著相关;细胞壁酶中,β-Gal活性和基因表达量增幅最快,α-Af和PG次之,PME活性和基因表达的增加时期相对滞后,且β-Gal和α-Af活性与硬度和各细胞壁组分的相关性强于PG和PME,PG与CSP和半纤维素表现较强相关性,而在PME上的相关性最差,说明细胞壁代谢与嘎拉果实软化密切相关,β-Gal和α-Af可能对果实软化的作用更强。     

不同干制方法对金丝小枣中糖类物质的影响

本文分别采用热风干燥法、日晒法和微波干燥法对金丝小枣进行干制,研究以上三种方法对红枣中可溶性糖、果胶含量及果胶分子量分布的影响。结果表明:与新鲜枣果相比,所有干制处理均导致山梨醇和蔗糖含量显著降低(p0.05),其中微波和日晒处理枣果的蔗糖保留率比热风处理组高,但其果糖与葡萄糖含量低于热风处理组。干制处理导致枣果细胞壁、水溶性果胶和溶于Na_2CO_3型果胶含量显著下降(p0.05),而其螯合性果胶含量显著增加(p0.05)。干制导致枣果果胶分子量显现不同趋势的变化。水溶性果胶组分:热风70℃或日光晾晒处理均导致高分子端组分的减少,热风50℃处理其分子量分布最为集中;溶于Na_2CO_3型果胶组分:干制导致高分子端果胶组分的增加,低分子端组分则发生降解。     

1-甲基环丙烯和不同贮藏温度对油桃果实硬度与细胞壁果胶的影响

以“中油 13 号”为试材,研究1-甲基环丙烯（1-Methylcyclopropene,1-MCP）和不同贮藏温度对油桃果实硬度与细胞壁果胶的影响。结果表明:1-MCP处理能有效地抑制常温下油桃果实硬度下降,贮藏第2 d,1-MCP处理组与未经1-MCP处理组油桃硬度分别下降12.31%和54.53%,差异极显著（P<0.01）,但贮藏后期抑制效果减弱,差异不显著（P>0.05）;而结合低温贮藏效果更好,贮藏至结束,1-MCP处理组与未经1-MCP处理组油桃硬度分别下降54.38%和62.96%,差异显著（P<0.05）。1-MCP主要通过影响油桃WSP半乳糖醛酸主链和阿拉伯糖支链的积累、CSP与SSP阿拉伯糖支链与半乳糖支链的分解,抑制油桃水溶性果胶（Water-soluble pectin,WSP）含量的升高与螯合性果胶（Chelate-soluble pectin,CSP）和碱溶性果胶（Sodium carbonate-soluble pectin,SSP）含量的降低,延缓油桃软化;低温主要通过抑制SSP阿拉伯糖支链与半乳糖支链的分解,减缓SSP含量降低,延缓油桃软化。油桃质地软化与果胶多糖的含量及主侧链变化密切相关,1-MCP处理和低温能有效地抑制贮藏期油桃硬度下降。     

超高压杀菌白萝卜汁的关键工艺研究

探讨白萝卜汁的热烫、酶解以及超高压杀菌工艺。结果表明：100℃热烫3min能使硫代葡萄糖苷酶完全失活;在酶解温度40℃、pH5.0、酶用量0.15g/L、酶解时间60min条件下,白萝卜的出汁率可达到81.48%;超高压处理对白萝卜汁具有显著的杀菌作用,且随压力的增大和处理时间的延长杀菌效果增加;经加速实验评价,500MPa处理1min可作为白萝卜汁的杀菌参数。     

Effect of Blanching and Drying on Pectin Constitutents and Related Characteristics of Dehydrated Peaches

The effects of sulfuring, blanching, dehydration, and storage (of dehydrated fruits), on the pectic constitutents and other characteristics of peaches are reported. Adequate blanching stabilized pectins of the dehydrated peaches so higher rehydration capacity and lower rehydration losses were observed after 5 min blanching. Increase in degradation was observed in nonblanched or 1.5 min heat-treated fruits, which resulted in lower rehydration capacity. A significant correlation was found between the contents of total pectin and protopectin fractions and the firmness or rehydration ratio of the peaches. Thus, pectin, one of the major cell-wall and intercellular tissue components, plays a significant role in determining the textural-structural characteristics of dehydrated fruits.     

High-humidity hot air impingement blanching (HHAIB) enhances drying behavior of red pepper via altering cellular structure,pectin profile and water state

In order to exploring a feasible pretreatment technology of red pepper, an emerging thermal pretreatment technology namely high-humidity hot air impingement blanching (HHAIB) was employed and its effect on drying behavior and related mechanisms were explored through analyzing the ultrastructure, the contents and composition of cell wall pectins, water state of red pepper during the blanching process under blanching temperature of 110 °C and relative humidity of 35%–40% for various exposure times ranging from 0 to 150 s. Results indicated HHAIB can extensively reduce the drying time from 11 h for the un-blanched samples to 8 h for the samples blanched for 90 s. In addition, HHAIB reduced the products' hardness by 8.19%–47.91% compared to the untreated samples. The cellular structure and water state experienced a significant alternation with the increasing blanching time. The content of water-soluble pectin (WSP) increased, while the contents of chelate-soluble pectin (CSP) and sodium‑carbonate-soluble pectin (NSP) decreased during the blanching process. Overall, HHAIB treatment is a promising blanching technology for red pepper as it can accelerate the drying process through softening tissue and altering the ultrastructure and moisture binding state.Industrial practiceDrying is one of the most frequently used methods for red pepper preservation as it can effectively reduce the moisture content so as to hinder the growth and reproduction of microorganisms and the moisture-mediated deteriorative reactions. While the existence of waxy hydrophobic layer covered the surface of red pepper results in long drying time and poor products' quality. In industrial practice chemical dipping is often used to remove the wax layer and enhance the drying rate of red pepper. However, the chemical residues can trigger food safety issues and how to deal with the highly corrosive chemical dipping solution is also a challenge. Therefore, it is very tempting for industry to explore innovative pretreatment for red pepper drying. The current work indicated that HHAIB is a promising alternative technology to replace the chemical dipping method as it extensively enhances the drying process of red pepper.     

Effect of blanching and drying treatments on quality of bamboo shoot slices

The enzymes activity, texture, pectin, microstructure and colour change in bamboo shoots (Dendrocalamus latiflorus) were examined to evaluate the effect of blanching and drying treatments on quality of bamboo shoot slices (BSS). Peroxidase (POD), phenylalanine ammonia‐lyase and polyphenol oxidase in BSS will become completely inactive at 95 °C for 6‐, 9‐ and 12‐min blanching treatments, respectively. The hardness and protopectin (PP) content decreased after the blanching treatment. Meanwhile, the content of water‐soluble pectin increased initially and then decreased gradually during the blanching. After the blanching treatment, the L* and a* of BSS decreased, while b* increased, ΔE > 2. The hardness of rehydrated BSS decreased by 43.57% after freeze drying (FD), which, however, decreased more after hot air drying (HAD). The pectin of rehydrated BSS was also determined to explain the hardness change in BSS. The BSS acquired similar microstructure of fresh samples after FD, while microstructure of BSS was severely damaged after HAD. The colour of BSS changes significantly after drying treatment. However, FD can maintain better colour of BSS than HAD. The results may provide a reference for industrial production of BSS.     

超高压处理对鲜切马铃薯质地及细胞壁多糖含量的影响

本文旨在探究鲜切马铃薯的质地随压力变化的规律及质地改变的机制。研究了超高压(HPP,100~600 MPa,10 min)对鲜切马铃薯色泽、硬度、咀嚼度、细胞壁相关酶活及多糖组成的影响。结果表明,HPP在压力≥ 500 MPa下对鲜切马铃薯的褐变抑制较好,300 MPa时褐变严重且程度高于空白。HPP相较传统热处理,能够更好的保持鲜切马铃薯的硬度及咀嚼度;但相比空白,HPP处理后硬度均有不同程度的下降,其中300 MPa时硬度下降最大,达到500 MPa时,硬度出现回升,咀嚼度在该压力下同样存在回升现象。HPP在一定程度上改变了马铃薯细胞壁相关酶活性及多糖含量,果胶甲酯酶(PME)活性在压力≤ 500 MPa具有稳定性,同时HPP可抑制多聚半乳糖醛酸酶(PG)和内切β-葡聚糖酶(Cx)活性,在压力100、500、600 MPa下提高β-葡糖苷酶及外切β-葡聚糖酶(C₁)活性;相比空白,HPP处理后鲜切马铃薯纤维素(CEL)、碱溶性果胶(NSF)、螯合性果胶(CSF)含量显著(P<0.05)提高,其中CSF含量在300 MPa下显著(P<0.05)低于空白水平,水溶性果胶(WSF)含量在100、600 MPa下显著(P<0.05)下降,其余压力下无显著变化,而经HPP处理后鲜切马铃薯半纤维素(HC)含量均显著(P<0.05)下降。经相关性分析,HPP处理后马铃薯硬度、咀嚼度与CSF、NSF、CEL含量呈显著或极显著正相关(P<0.05或P<0.01),与WSF含量呈极显著(P<0.01)负相关,与HC含量相关性不显著,PME活性对其质构指标影响较大。综上,超高压处理后细胞壁多糖组成及含量变化影响了鲜切马铃薯的质地。     

豆薯软罐头质地变化及贮藏动力学研究

为考察豆薯罐头加工适应性、丰富豆薯产品种类,以豆薯为原料,探讨了热烫、杀菌、贮藏对其质构特性的影响。结果显示:热烫处理4 min后豆薯的硬度、凝聚性、咀嚼性、回复性、弹性分别为新鲜豆薯的63.2%、43.9%、17.7%、51.4%、69.8%;预煮和杀菌阶段豆薯质地变软,其硬度、凝聚性、咀嚼性、回复性、弹性分别为处理前的79.5%与74.64%、54.7%与105.33%、18.0%与98.73%、73.0%与105.18%、44.8%与98.19%;在常温或低温下贮藏180 d,豆薯的各项质构指标均较未处理豆薯有所下降。因此通过适当控制上述加工方式和采用低温贮藏可延缓豆薯罐头的软化;此外,将各质构参数进行贮藏动力学分析发现:一级动力学模型能很好的反映其质构变化。     

Vacuum-steam pulsed blanching (VSPB) softens texture and enhances drying rate of carrot by altering cellular structure,pectin polysaccharides and water state

As a new type of blanching technology, vacuum-steam pulsed blanching (VSPB) has higher blanching efficiency and quality, but the mechanism of this technology on texture softening and drying enhancement is still unclear. In this study, the mechanism was revealed from texture, pectin, nanostructure, cell ultrastructure, calcium, and water state. Results revealed that VSPB treatment reduced the hardness and chewiness, increased water-soluble pectin, decreased sodium‑carbonate-soluble and chelate-soluble pectin concentration, and resulted in depolymerization and degradation of pectin nanostructure. However, transmission electron microscopy showed that blanching damaged the cell wall structure and the integrity of the middle layer. Scanning electron microscope - Energy dispersive X-ray spectroscopy measurement observations indicated that lipid droplets containing calcium ions were formed under the action of VSPB. In addition, low field nuclear magnetic resonance showed that the redistribution of moisture in carrot was facilitated by VSPB. The findings reveal the mechanism of texture softening and drying rate enhancement driven by blanching.Industrial relevanceThermal blanching is an essential thermal treatment for many fruits and vegetables processing. Hot water blanching and steam blanching are the two most frequently employed blanching methods due to simple to establish and easy to operate. However, hot water and steam blanching holds several disadvantages, e.g., hot water blanching requires a huge amount of water and generates an excessive amount of wastewater, particularly loss of water-soluble nutrients during blanching due to leaching and diffusion, while for steam blanching, the existence of air and water vapor among the piled materials leads to low blanching efficiency and un-uniform heating. VSPB is an innovative steam blanching method. In the VBSP process, the air and water vapor are expelled by the vacuum pump to facilitate steam deep penetration in the materials, particularly the piled materials, so as to improve blanching efficiency and uniformity. Previous study indicated VSPB could soften texture and reduce the drying time of carrot, but the mechanism was not clear. The current work reveal that VSPB softens texture and enhances drying rate of carrot via micro-, ultra-structure modification, pectin polysaccharides degradation and changes of water state. The findings have important implications for understanding and controlling the blanching triggered texture formation and drying enhancement.     

短时高浓度二氧化碳处理对冰温贮藏期间葡萄果实软化生理的影响

以‘乍娜’葡萄为试材,考察冰温贮藏条件下不同高浓度外源CO2处理对贮藏过程中葡萄好果率、硬度及软化生理指标的影响,分析各指标间的相关性,以期为葡萄新型无硫保鲜技术的开发提供切实的方法和理论依据。结果表明,10%CO2能够使冰温贮藏过程中葡萄好果率和果实硬度保持在较高水平,有效抑制果实原果胶含量的下降及多聚半乳糖醛酸酶(PG)、纤维素酶(Cx)及β-半乳糖苷酶(β-Gal)活性的升高;贮藏过程中,葡萄果实好果率与果实硬度呈极显著正相关,果实硬度与原果胶含量呈极显著正相关,与PG和β-Gal活性呈极显著负相关。由此可见,适宜浓度短时CO2处理可通过调控葡萄果实中软化相关生理机制,从而抑制果实软化,提高果实贮藏品质。     

一氧化氮熏蒸处理对甜瓜采后细胞壁代谢及黑斑病控制的影响

为探究NO熏蒸处理对甜瓜果实采后细胞壁代谢和抗病性的影响,用60 μL/L的NO熏蒸‘西州蜜25号’甜瓜3 h,常温下放置12 h后,接种交孢链格孢菌（Alternaria alternata）,置于常温下贮藏,定期测定甜瓜果实接种发病率、硬度、细胞膜渗透率和原果胶、可溶性果胶、纤维素质量分数及多聚半乳糖醛酸酶（polygalacturonase,PG）、果胶甲酯酶（pectin methyl esterase,PME）和纤维素酶（cellulase,Cx）的活力,并通过扫描电子显微镜观察果实瓜皮结构变化。结果表明：采后60 μL/L NO熏蒸处理能够有效降低甜瓜果实采后病斑直径、病斑深度及发病率,维持较高的果实硬度和原果胶、纤维素质量分数,减缓细胞膜渗透率、可溶性果胶质量分数的上升,降低PG、PME、Cx活力;扫描电子显微镜结果显示NO处理能够抑制瓜皮表面气孔结构及裂纹部位菌丝的生长,较好地维持气孔结构的完整性。说明适量外源NO熏蒸处理可减缓细胞壁代谢进程,增强采后果实抗病防御能力。