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1.
The mode of change in a range of physiological, physicochemical and biochemical parameters during fruit ripening between distinct peach genotypes (Prunus persica L. Batsch) after cold storage for up to 4 weeks was determined. The nectarine cultivar ‘Caldesi 2000’ was selected as a genotype with melting flesh (MF) characteristic (fruits characterized by extensive flesh softening during ripening) and the cultivar ‘Andross’ as a genotype with non‐melting flesh (NMF) characteristic (fruits characterized by limited flesh softening during ripening). Flesh firmness, ethylene production, physicochemical and biochemical properties of the cell wall were determined and significant differences between the fruits of the two genotypes were recorded. Fruits of the NMF genotype were characterized by higher tissue retention and ethylene production during their ripening, higher content of uronic acids, as well as higher capacity for calcium binding in the water‐insoluble pectin fraction compared with fruits of the MF genotype. Additionally, the ripening of MF‐type fruits was characterized by higher losses of neutral sugars, especially those of arabinose and galactose than the NMF‐type fruits and these losses were more intense after extended cold storage periods. In fruits of the NMF genotype the decreased activity of pectin methyl esterase (PME) combined with higher levels of calcium in the water‐insoluble pectin fraction possibly provided less substrate for polygalacturonase (exo‐, endo‐PG) activity and less solubility of cell wall pectin compared with fruits of the MF genotype. Overall, the data indicate the existence of a wide range of diverse metabolic pathways during fruit ripening of fresh fruits with MF and NMF characteristics. Copyright © 2005 Society of Chemical Industry  相似文献   

2.
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。  相似文献   

3.
阚娟  刘涛  金昌海 《食品工业科技》2012,33(11):354-358,362
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。  相似文献   

4.
《LWT》2005,38(5):519-527
The chemical and quality characteristics of ‘Olinda’ and ‘Campbell’ oranges (nucellar budlines from Valencia late cultivar) were evaluated after exposure to a fruit core temperature of 44 °C and held at 44 °C for 100 min or 46 °C and held at 46 °C for 50 min, subsequent storage at 6 °C for 2 weeks and an additional week of simulated marketing period (SMP) at 20 °C. Exposure to either heat treatment caused neither visible damage nor fruit softening. Fruit weight loss rate in ‘Olinda’ oranges was unaffected by treatment but was higher than control fruit in heat exposed ‘Campbell’ oranges after storage, though at the end of SMP differences between treated and untreated fruit were non-significant. While neither heat treatment affected decay incidence in ‘Olinda’ oranges, significantly less decay was found in heat treated ‘Campbell’ fruit compared to control fruit both during storage and SMP.The chemical analyses of flavedo tissue of ‘Olinda’ oranges revealed that there were no treatment differences in neutral sugars, soluble and insoluble pectins and calcium bound to insoluble pectin fraction. The calcium content bound to soluble pectin fractions increased following heat treatments. At the end of SMP there was a significant decrease of soluble pectin and a significant increase of calcium bound to insoluble pectins in flavedo from oranges of the 46 and 44 °C treatments.Following treatment at 46 °C ‘Olinda’ fruit had a significantly lower content of soluble solids concentration. However, differences in soluble solids concentration between treated and control fruit after storage and SMP were not significant.Post-treatment levels of ethanol in both cultivars were significantly higher than in non-treated fruit. During storage and SMP, significant increases of ethanol were detected in control fruits with respect to their initial levels, whereas a reverse trend occurred in fruit subjected to heat treatment. Upon termination of the heat treatment at 44 or 46 °C, mean taste scores of ‘Olinda’ oranges were lower than those of untreated fruit, while the taste of ‘Campbell’ oranges was adversely affected only by the 46 °C treatment. After storage and SMP, taste differences between treated and control fruit were not significant. Flavour scores were unaffected by the treatment at 44 °C. Following treatment at 46 °C flavour rating in ‘Olinda’ fruit was significantly lower than control fruit while after storage and SMP the differences in flavour scores between treated and untreated fruit were non significant. Heat treatment to a fruit core temperature of 44 °C for 100 min or 46 °C for 50 min can thus have important commercial applications as an alternative to toxic chemical fumigants or to longer and more expensive disinfestation treatments such as cold quarantine.  相似文献   

5.
Pre‐harvest calcium sprays with calcium chloride or with a commercial chelated calcium form at equivalent calcium rate were applied in nectarine trees at weekly intervals beginning 4 or 8 weeks before harvest, respectively. The fruits were harvested at commercial maturity stage and cold stored (0 °C, 95% RH) for 0, 2, 4 and 6 weeks, prior to their ripening at room temperature (20 °C) for 1 and 5 days. The interrelations between calcium content (total, cell wall and pectin‐bound), cell wall components (polyuronide, neutral sugar and cellulose content) and tissue firmness of the nectarine fruits were examined. The two strategies (four or eight calcium sprays) were equally effective at increasing the fruit calcium content. Calcium increased by 14–25% in the peel and by 8–11% in the flesh, whereas cell wall calcium increased by 7–17% in calcium‐sprayed compared to non‐sprayed fruits after harvest. Cell wall and pectin calcium increased with the increase of storage time both in sprayed and non‐sprayed fruits without a corresponding increase of total calcium and uronic acid content, indicating the formation of more sites for calcium binding as storage period increased. Neutral sugar and cellulose content remained unaffected by the application of calcium sprays. Copyright © 2006 Society of Chemical Industry  相似文献   

6.
BACKGROUND: Firmness in vegetables is an important textural attribute affecting consumer attitudes toward freshness and quality. Firmness, structural carbohydrates, polygalacturonase (PG), and pectin methylesterase (PME) activity were measured in three onion (Allium cepa L.) lines at harvest and after 4, 8, and 12 weeks of storage. RESULTS: The high‐dry‐matter onion, MBL87‐WOPL, had the firmest bulbs at harvest and delayed softening during storage. MBL87‐WOPL had the thickest cell wall/middle lamella region, and highest levels of dry matter and total uronic acid. Furthermore, MBL87‐WOPL had the lowest levels of PG and PME activity during storage. Pegasus, a poor‐storing cultivar, had the softest bulbs at harvest, lowest levels of uronic acid, and thinnest cell wall/middle lamella. A good storing, moderately firm onion cultivar (MSU4535B) presented intermediate levels of firmness and total uronic acid content. Differences in uronic acid in water‐soluble pectin accounted for much of the difference in total uronic acid among lines. Cellulose concentrations were similar among all lines at harvest. In addition, cellulose concentrations decreased in all lines during storage. Transmission electron microscopy performed on bulbs at harvest and after 12 weeks of storage indicated that degradation of the middle lamella had occurred during storage, leading to cell separation. CONCLUSION: Our results suggest that differences in onion scale firmness at harvest may be due to differences in water‐soluble pectin uronic acid concentrations. Furthermore, the rate of bulb softening during storage at 6.6 °C was greater in onion lines with higher levels of PME and PG activity in storage. Copyright © 2008 Society of Chemical Industry  相似文献   

7.
以‘秦美’猕猴桃果实为试材,于盛花期后28 d分别采用0(对照,清水)、5、10、20 mg/L 4 个质量浓度的氯吡脲(1-(2-chloropyridin-4-yl)-3-phenylurea,CPPU)溶液进行蘸果处理,蘸果时间3~5 s,研究采前CPPU处理对‘秦美’猕猴桃贮藏期间果实硬度及细胞壁降解酶活力的影响。结果表明:CPPU处理加速了果实硬度、原果胶和纤维素质量分数的下降,提高了可溶性果胶质量分数及多聚半乳糖醛酸酶(polygalacturonase,PG)、果胶甲酯酶(pectin methylesterase,PME)、纤维素酶(cellulase,Cx)和β-半乳糖苷酶(β-D-galaetosidase,β-Gal)细胞壁降解活力。各处理组果实硬度与可溶性果胶质量分数和PG、Cx活力呈极显著负相关(P<0.01),与原果胶、纤维素质量分数呈极显著正相关(P<0.01);20 mg/L CPPU处理组果实的β-Gal活力与硬度呈显著负相关(P<0.05)。CPPU处理提高了果实细胞壁降解酶的活力,促进了细胞壁的降解,加速了贮藏期间果实的软化,降低了果实的耐贮藏性。为维持猕猴桃采后果实硬度,延长贮藏期,生产中不宜使用CPPU处理,或使用的质量浓度不宜超过5 mg/L。  相似文献   

8.
The pectic and hemicellulosic cell wall polysaccharides from the pulp and the peel of white-flesh and red-flesh dragon fruits (Hylocereus spp.) were isolated and compared in terms of degree of methoxylation (DM), solubility properties (relative content of uronic acids and neutral sugars in different fractions), neutral sugar composition, molar mass distribution, and affinity toward some specific anti-pectin antibodies. Hereto, the alcohol-insoluble residues were extracted and sequentially fractionated using hot water, a chelating agent, sodium carbonate, and potassium hydroxide solutions to obtain different pectin fractions and a hemicellulose fraction. Chemical analyses were used to characterize these polysaccharide fractions. The results show that cell wall polysaccharides of the pulp and especially of the peel from white-flesh and red-flesh dragon fruits contain significant amounts of pectic substances that are lowly methyl-esterified. The cell wall polysaccharides of the peel as well as those of the pulp contain high amounts (38–47 %) of loosely bound (water-soluble) pectic substances. In the water-soluble fraction (WSF) of the peel samples, uronic acids are the predominant monomers. On the contrary, rhamnogalacturonan-I type neutral sugars, and especially arabinose and galactose, contribute equally, as compared to uronic acid, to the WSF of the pulp samples. Despite the low average DM value of pulp and peel pectin, pectic substances in both samples showed affinity for antibodies with different specificities indicating that a wide range of epitopes, including long blocks of unesterified galacturonic acids (GalA) residues as well as (short) blocks of esterified GalA residues, is present. No large differences between the pectic substances among the different dragon fruit varieties were observed.  相似文献   

9.
研究了细胞壁组分及其降解酶活性的变化与茄子果实采后软化的关系。结果表明,采后茄子果肉硬度随贮藏时间的延长而不断下降。贮藏期间果肉水溶性果胶(WSP)含量在贮藏前12天不断增加,之后快速下降,而共价结合型果胶(CSP)、半纤维素和纤维素等细胞壁组分含量持续减少。果肉果胶甲酯酶(PME)、多聚半乳糖醛酸酶(PG)和纤维素酶(CX)活性均呈先升高后下降趋势,分别在贮藏至第6、9、12天达到最大值;β-半乳糖苷酶(β-Gal)活性始终保持较高水平,且在整个贮藏期间活性变化不明显。相关性分析结果表明,CSP、半纤维素和纤维素的降解与采后茄子果实软化密切相关,PG和CX在茄子果实采后软化过程中起着重要的作用。  相似文献   

10.
BACKGROUND: High‐temperature conditioning (3 days at 37 °C and 95% relative humidity), which protects ‘Fortune’ mandarins from chilling injury (CI), manifested as pitting in the outer part of the peel (flavedo), was applied prior to cold storage (2 °C) in order to investigate the involvement of cell wall composition in the chilling tolerance of mandarins. RESULTS: Both low‐temperature storage and high‐temperature conditioning barely modified the alcohol‐insoluble substance (AIS) content or the degree of pectin esterification in the flavedo. Water‐soluble pectins (WSP) were higher in heat‐conditioned than in non‐conditioned fruits at the onset of CI. In addition, the heat‐conditioning treatment was able to increase chelator‐soluble pectins (CSP) after short cold storage periods. Covalently bound polyuronides in alkali‐soluble pectins (ASP) increased only in fruits with high incidence of CI. Cellulose and hemicellulose increased at 2 °C in both conditioned and non‐conditioned fruits, indicating that these polysaccharides may be altered by low temperature but are not related to chilling‐induced damage. CONCLUSION: High‐temperature conditioning may reduce chilling‐induced flavedo pitting in ‘Fortune’ mandarin fruit by maintaining normal levels of WSP and increasing putative sites for calcium bridge formation within the cell wall, but not by inducing changes in other matrix cell wall components. Copyright © 2012 Society of Chemical Industry  相似文献   

11.
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。  相似文献   

12.
NO处理对采后莲雾果实絮状绵软进程的影响   总被引:1,自引:0,他引:1  
高维亚  吴光斌  陈发河 《食品科学》2016,37(18):208-215
探明NO处理对采后莲雾果实成熟衰老过程中絮状绵软进程的影响。以台湾‘黑珍珠’莲雾果实为材料,用不同用量(5、10、20 μL/L)外源NO熏蒸处理莲雾果实,以0 μL/L NO熏蒸处理作对照,研究其对采后莲雾果实生理及品质、细胞壁代谢及木质素代谢的影响。结果表明:与对照相比,不同用量外源NO熏蒸处理能够显著抑制莲雾果实贮藏过程中絮状绵软指数及质量损失率的上升,保持果实硬度,延缓果实纤维素含量的下降,10 μL/L NO显著降低了多聚半乳糖醛酸酶(PG)、果胶甲酯酶(PME)、β-半乳糖苷酶(β-Gal)活性。同时,不同用量外源NO熏蒸处理能够延缓果实木质素含量的上升,10 μL/L NO显著降低了苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、4-香豆酸辅酶A连接酶(4-CL)活性。相关性分析表明,絮状绵软指数与质量损失率、果肉硬度、纤维素含量和木质素含量之间均存在显著相关性,且与原果胶含量呈极显著负相关,与可溶性果胶含量呈极显著正相关。NO处理能够抑制细胞壁类物质降解酶活性,延缓采后莲雾果实絮状绵软进程,延长果实贮藏期,其中以10 μL/L NO处理效果最好。  相似文献   

13.
为了探明一氧化氮(NO)抑制采后芒果软化的作用机理,将"台农"芒果果实在0.25 mmol/L硝普钠(SNP,NO供体)溶液浸泡处理20 min,常温(20±2) ℃贮藏20 d,定期测定果实硬度、细胞壁组分含量、细胞壁水解酶活性。结果表明,与未处理果实相比,SNP处理显著降低贮藏20 d内果实中多聚半乳糖醛酸酶(PG)活性(p<0.05),显著抑制贮藏10 d内果实纤维素酶(CX)(p<0.05)活性,极显著抑制β-半乳糖苷酶(β-Gal)和α-L-阿拉伯呋喃糖苷酶(α-L-Af)活性(p<0.01),但使贮藏15~20 d期间果实CX和β-Gal活性及贮藏第20 d的α-L-Af活性均显著增加(p<0.05)。SNP处理显著抑制贮藏5 d内果胶甲酯酶(PME)活性(p<0.05),但在贮藏10~20 d期间保持较高的PME活性(p<0.05)。此外,SNP处理极显著延缓原果胶和纤维素的降解(p<0.01),减少可溶性果胶含量的增加(p<0.05),从而降低贮藏期间果实硬度的损失。硬度与原果胶、纤维素含量均呈极显著正相关(p<0.01),而与CX活性呈显著负相关(p<0.05),与可溶性果胶含量、PG、β-Gal和α-L-Af活性均呈极显著负相关(p<0.01)。可溶性果胶含量与纤维素含量呈极显著负相关(p<0.01),而与α-L-Af活性均呈显著正相关(p<0.05),与PG和β-Gal活性均呈极显著正相关(p<0.01)。因此,采后SNP处理可以通过调节果实细胞壁降解酶活性,减少细胞壁组分的降解,从而延缓芒果采后软化,延长贮藏期。  相似文献   

14.
The effects of processing treatments on the microscopic structure, pectic fractions and firmness of ripe olives (Olea europaea L Cassanese variety), processed by the ‘Ferrandina’ method for oven‐dried table olive production, were studied. The process included a first heating step, a salting step and a final oven‐drying process. Scanning electron microscopic observations of olive tissue structure revealed that heat treatment was highly damaging, affecting the intercellular pectic substances and producing cell separation. Epicuticular waxes were barely affected and limited the shrivelling of the fruit during the oven dehydration process. The pectin content was higher in the oven‐dried olives than in the fresh samples. The sodium hydroxide‐soluble fraction was the main pectin fraction in the olive tissues. Its content decreased markedly after the heating step, while it increased after the oven dehydration step. The softening of the olive tissues increased after heat treatment, and a correlation was found between protopectin content and firmness. In oven‐dried olives a firming of the olive tissues was observed due to the de‐esterification of pectin and to its decreased solubility resulting from an increase in cell wall calcium bridging. © 2000 Society of Chemical Industry  相似文献   

15.
The influences of soaking treatment and storage conditions on the softening of cooked beans, namely, soybeans and red kidney beans, were investigated. It was revealed that the softening of fresh soybeans and fresh red kidney beans was suppressed during subsequent boiling after soaking treatment at 50 and 60 °C. Furthermore, in treated aged soybeans and red kidney beans that were subjected to storage at 30 °C/75% relative humidity for 6 mo and soaking treatment at 50 to 60 °C, the hardness during cooking was further amplified. This suggested that the mechanism of softening suppression differs depending on the influences of soaking and storage. Analysis of the pectin fraction in alcohol insoluble solid showed insolubilization of metal ions upon storage at high temperature and high humidity in both soybeans and red kidney beans, which suggests interaction between Ca ions and hemicellulose or cellulose as cell wall polysaccharides. The results of differential scanning calorimetry (DSC) showed that aged soybeans exhibited a shift in the thermal transition temperature of glycinin‐based protein to a higher temperature compared with fresh soybeans. From the results of DSC and scanning electron microscopy for aged red kidney beans, damaged starch is not conspicuous in the raw state after storage but is abundant upon soaking treatment. As for the influence of soaking at 60 °C, it can be suggested that its influence on cell wall crosslinking was large in soybeans and red kidney beans in both a fresh state and an aged state.  相似文献   

16.
1-甲基环丙烯对采后南果梨果实软化的影响   总被引:1,自引:0,他引:1  
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。  相似文献   

17.
18.
邢颖  徐怀德 《食品工业科技》2022,43(23):401-407
果胶是植物细胞壁胞间层的主要成分,果胶酶存在于天然植物组织中,可以催化果胶分解,进而破坏细胞壁的完整性,使得果蔬硬度下降。在贮藏过程中影响果蔬软化的因素主要有乙烯、Ca2+及温度等。常见的果蔬保鲜技术包括有物理、化学及生物保鲜技术,不同的保鲜技术对果蔬软化的机制不同。本介绍了果胶的结构及果胶酶的分类,同时总结了影响果胶酶活性的主要因素及其常见贮藏保鲜技术对果胶酶的影响,为果蔬贮藏保鲜过程中抑制软化的研究奠定理论基础。  相似文献   

19.
冰温贮藏对柿果细胞壁物质代谢的影响   总被引:2,自引:0,他引:2  
为探讨冰温贮藏对柿果采后成熟软化的作用效果,比较研究了冰温贮藏和普通冷藏对柿果细胞壁物质代谢的影响.结果表明,冰温贮藏相比普通冷藏,显著抑制了柿果PG和Cx酶活性,延缓纤维素和原果胶降解以及水溶性果胶含量的增加,较好地保持了果实硬度.贮藏至90d,冰温贮藏柿果的硬度是普通冷藏的1.66倍,表明采用冰温贮藏可延缓柿果实的软化进程,从而延长贮藏期.  相似文献   

20.
Two different heat treatments were compared as to their efficacy in preventing decay and maintaining post-harvest quality of Golden Delicious (Malus domestica Borkh). The apples were treated with a hot water rinsing and brushing machine (HWRB) for different temperatures, and compared to apples given a dry heat treatment (96 h at 38°C) and untreated apples. HWRB at 55°C for 15 s significantly reduced (at P=0.05) decay development in Penicillium expansum-inoculated fruit after 4 weeks at 20°C, or in naturally infected fruit after prolonged storage of 4 months at 1°C plus 10 days at 20°C. This treatment inhibited ripening processes as measured by relatively low respiration rate and ethylene evolution and a slow colour development, compared with non-heated control, and fruit quality was maintained. Heat damage was observed on fruit rinsed and brushed at 60 or 65°C for 15 s. Although similar results were obtained in decay control and fruit quality of HWRB-55°C treated fruit and dry heated fruit, the commercial application of this short pre-storage heat treatment is more feasible than the dry heat treatment.  相似文献   

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