茶多酚对采后猕猴桃果实生理生化变化的影响

猕猴桃果实贮藏过程中，硬度下降分为两个明显阶段，第一阶段硬度下降较快，主要与淀粉快速水解有关；第二阶段硬度下降趋于缓和，主要与果胶物质水解有关。茶多酚处理能有效降低淀粉酶活性及果胶酶活性，因而果实中淀粉及果胶水解得以抑制，同时果实中呼吸强度和相对透性明显降低，可溶性固形物上升得到减缓，从而延缓了果实衰老。     

茶多酚对采后猕猴桃果实生理生化变化的影响

猕猴桃果实贮藏过程中，硬度下降分为两个明显阶段，第一阶段硬度下降较快，主要与淀粉快速水解有关；第二阶段硬度下降趋于缓和，主要与果胶物质水解有关。茶多酚处理能有效降低淀粉酶活性及果胶酶活性，因而果实中淀粉及果胶水解得以抑制，同时果实中呼吸强度和相对透性明显降低，可溶性固形物上升得到减缓，从而延缓了果实衰老。     

‘黄冠’梨采后热处理和钙处理对其钙形态及细胞壁物质代谢的影响

 以‘黄冠’梨为材料,研究了采后热处理（38 ℃热空气24 h）,钙处理（6% CaCl₂浸果15 min）及热加钙处理（6% CaCl₂ + 38 ℃）对果实低温贮藏过程中钙形态及细胞壁物质代谢的影响,以清水浸果为对照。结果表明：果胶钙为果实中主要的钙形态,其含量占全钙的49.7% ~ 55.8%,钙处理、热加钙处理果实的总钙含量与对照相比分别增加了22.95和31.58 µg · g^-1;钙处理、热加钙处理显著抑制了果实纤维素、原果胶、水溶性钙及果胶钙含量的下降,促进了草酸钙含量的增加,延缓了果实硬度的下降;热处理、热加钙处理显著降低了多聚半乳糖醛酸酶（PG）、果胶甲酯酶（PME）和纤维素酶活性。相关分析表明,果实硬度与纤维素、原果胶、水溶性钙和果胶钙含量呈极显著正相关,与可溶性果胶含量呈极显著负相关;PG和纤维素酶与果实硬度均呈极显著负相关,PME与果实硬度的相关性不显著。钙处理、热加钙处理通过抑制可溶性钙向难溶性钙转化、细胞壁组成成分降解以及降低细胞壁降解酶活性,延缓果实软化,其中以6% CaCl₂ + 38 ℃的处理效果最好。     

不同钙处理对采后草莓果实细胞壁酶活性、果胶含量的影响

采后钙处理可有效地降低草莓果实中Cx-cellulase、PG、β-Gal的活性,抑制原果胶的降解和水溶性果胶的产生,延缓细胞壁的水解.5?Clz 100 mg/LGA3 1.2%壳聚糖浸果比其它处理效果更为明显.     

1-甲基环丙烯处理对软枣猕猴桃果实软化的影响

以软枣猕猴桃为试材,研究了果实采后不同浓度1-甲基环丙烯(1-MCP)处理对软枣猕猴桃果实软化中果实品质、乙烯释放量和呼吸强度、细胞壁成分含量和果胶分解酶活性的影响。结果表明:1-MCP处理明显延缓了软枣猕猴桃果实可溶性固形物含量的上升、可滴定酸含量的下降和果实硬度下降速度;1-MCP处理抑制了软枣猕猴桃果实的呼吸峰值,推迟了软枣猕猴桃果实乙烯发生高峰出现的时间;抑制了软枣猕猴桃果实中果胶、纤维素和半纤维素的降解;降低了软枣猕猴桃果实多聚半乳糖醛酸酶活性峰值,而且推迟了软枣猕猴桃果实β?半乳糖醛酸酶活性峰值的出现。可见,1-MCP处理显著延缓了软枣猕猴桃果实的软化。     

采后猕猴桃果实乙烯产生的变化及其与衰老的关系

中华猕猴桃和美味猕猴桃果实在衰老期间的乙烯释放速度和呼吸强度前期逐渐上升,后期下降,呈峰型变化。降低温度和改变气体成分,可推迟高峰的出现。衰老期间原果胶/总果胶的比值不断下降,果肉硬度随之降低。美味猕猴桃的内源乙烯含量和呼吸强度皆低于中华猕猴桃。原果胶/总果胶的比值和果肉硬度的变化可作为猕猴桃果实衰老的一种标志。     

钙在乙烯促进网纹甜瓜果实软化过程中的作用

以网纹甜瓜为试材, 通过测定果实硬度、呼吸速率、乙烯释放量、1-氨基环丙烷基羧酸(ACC) 含量及ACC合成酶(ACS) 和ACC氧化酶(ACO) 的活性, 研究钙在乙烯促进网纹甜瓜果实软化过程中的调控作用。结果表明: 采用浓度为015%外源硝酸钙处理1 h和10μL·L^-1外源乙烯处理24 h, 乙烯处理可提高网纹甜瓜果实中水溶性钙含量, 降低果胶酸钙的含量, 提高果实的呼吸速率, 缩短呼吸跃变高峰出现的时间, 并通过提高ACC含量以及ACS和ACO活性, 提高了乙烯释放量; 先乙烯处理后增施钙可进一步提高水溶性钙含量并降低果胶酸钙的含量和提高呼吸速率、ACC含量、ACS和ACO活性以及乙烯释放量。但单施钙可明显提高果实中果胶酸钙的含量, 推迟降低了呼吸速率, 推迟ACC含量、ACS和ACO活性峰值出现的时间及峰度值, 从而降低了果实的乙烯释放量; 而与单用钙处理相比, 先钙后乙烯处理在一定程度上提高了呼吸速率、ACO活性和乙烯释放量, 但是以上各指标仍低于对照。由此可见, 钙虽然具有延缓网纹甜瓜果实软化的作用, 但可促进乙烯诱导条件下网纹甜瓜果实的软化。     

采后钙及热处理对葡萄柚果实贮藏期细胞壁物质代谢的影响

以“里约红”葡萄柚果实为试材,用3％ CaCl2、50℃热水单独、复合浸泡处理5 min,在 室温(18±2)℃、相对湿度85％～90％的环境条件下贮藏,研究采后钙、热处理对葡萄柚果实的贮藏效果及细胞壁物质代谢的抑制作用.结果表明:采后钙、热处理有效控制了果实硬度下降、失重率上升,维持果实共价结合型果胶(SCSP)、24％半纤维素(24KSF)含量,降低了果实水溶性果胶(WSP)、果实离子型果胶(ESP)、4％果实半纤维素(4KSF)含量.其中,以3％CaCl2+50℃处理效果最佳,贮藏75 d果实硬度、乙醇不溶物、果实共价结合型果胶(SCSP)、24KSF分别比对照高出21.31％、6.44％、22.60％和50.46％.此外,钙处理效果优于50℃热处理.相关性分析结果表明,果实硬度与细胞壁各组分呈显著相关.通过主成分分析构建的综合评价模型可知,采后钙、热处理可提高贮藏期间葡萄柚果实质地综合品质,抑制细胞壁物质代谢降解,从而延长葡萄柚果实贮藏期.     

采前叶面喷施螯合钙对草莓品质、钙形态和贮藏期灰霉病的影响

以晶玉草莓为材料,研究采前叶面喷施螯合钙对草莓果实品质、果实钙不同形态含量及贮藏期草莓灰霉病病情指数等的影响。结果表明:采前叶面喷施螯合钙能显著提高草莓成熟期果实硬度、可溶性固形物含量和维生素C含量,显著降低贮藏期草莓灰霉病病情指数;果胶酸钙是草莓果实中主要钙形态,其含量占果实中总钙含量的27.3%~33.2%;相关性分析表明,草莓果实硬度与果胶酸钙含量呈显著正相关,总钙含量与水溶性有机酸钙、果胶酸钙、磷酸钙含量呈显著正相关,硝酸钙与草酸钙含量呈显著负相关,叶面喷施螯合钙处理可促进草莓果实中可溶性钙向难溶性钙转化,延缓果实软化,其中以绿熟期喷施5 mmol/L螯合钙处理效果最好。     

采后不同钙浓度处理对贮藏期间苹果硬度及果胶含量的影响

以"富士"苹果为试材,采用0%、2%、3%、4%4种不同浓度的CaCl2浸泡果实,研究了苹果采后不同浓度钙处理对贮藏期间苹果果实硬度和不同种类果胶含量的影响,以期探明莱西地区"富士"苹果采后钙处理的最适应浓度。结果表明:随着贮藏时间的延长,苹果果实的硬度下降,水溶性果胶(WSP)含量增加,共价结合果胶(CSP)含量减少,离子型果胶(ISP)含量变化不大;苹果果实硬度与WSP含量呈极显著负相关,与CSP含量呈极显著正相关,与离子型果胶(ISP)无显著相关性;与对照相比,不同浓度的钙处理都能改善贮藏期间苹果果实的硬度,能减缓WSP含量的增加和CSP含量的减少;4种浓度的钙处理中以2%CaCl2处理的效果最好;采后钙处理能有效保持苹果在贮藏期间的硬度,有效减缓WSP含量的增加和CSP含量的减少,从而延缓了果实的软化,延长了苹果的货架寿命。     

猕猴桃总淀粉酶活性与果实软化的关系

猕猴桃采后的软化过程分为两个明显的阶段，其中第一阶段果实的快速软化与淀粉酶活性的上升所引起的淀粉的快速降解显著相关（Ｒ＝０．９９）。用机械伤或乙烯处理可提高淀粉酶的活性，加速淀粉的降解，从而促进了果实的软化。与冷藏相比，气调贮藏可明显地阻止淀粉酶活性的上升，减少淀粉的降解，因而较好地保持果实的硬度。     

Cropping effects on the loss of apple fruit firmness during storage: The relationship between texture retention and fruit dry matter concentration

Firmness is a primary measure of apple fruit texture, the key determinant of eating quality of apples. Despite the well developed understanding of the process of firmness loss in storage, there is very limited information concerning pre-harvest and at-harvest causes of the variation in fruit quality in the marketplace. The objective of the present study was to investigate the respective roles that the factors of time and intensity of crop thinning, fruit size and fruit dry matter concentration (DMC) each may have in determining fruit firmness of ‘Royal Gala’ apple at harvest and during storage. Loss of firmness during storage of all thinning treatments and of fruit size and DMC categories was described by a bilinear equation. Time of thinning did not influence any aspect of fruit softening during air storage at 0.5 °C. Comparing the crop loads, a lower crop load (100 fruit per tree) resulted in firmer fruit at harvest. The loss of firmness during storage associated with crop load occurred because fruit from the lowest crop load softened more rapidly during the second slow phase of softening. Fruit firmness was positively correlated with fruit size where larger fruit were slightly firmer than smaller fruit at harvest but not after storage. The softening profiles of different sized fruit were similar except for a class of extremely small fruit, which appeared to soften more rapidly during the second slow softening phase of storage. Both at-harvest and post-harvest fruit firmness were influenced by fruit DMC. Fruit firmness at harvest increased significantly as fruit DMC increased from 13% to above 16%. Despite having significantly different initial firmness, all fruit classes with DMC higher than 13% softened at a similar rate during both the initial rapid and second slow softening phases and the transition between the two phases occurred after the same time in storage. In contrast, fruit with very low DMC, less than 13%, had a greater rate of softening in the second phase. These results indicate that variation in fruit firmness at harvest and after storage is influenced by processes that affect and alter fruit DMC during fruit development. In this respect crop load control, which is used to improve fruit size, was also an important factor in altering fruit DMC, thereby affecting firmness at harvest and after storage. Furthermore, the effects of DMC on fruit firmness were independent of fruit size.     

Controlled-atmosphere storage of kiwifruit. I. Effect on fruit firmness and storage life

The effect of atmospheres containing high CO₂ and low O₂ on the firmness of kiwifruit (Actinidia chinensis Planch.) during cool storage at 0°C has been studied. Atmospheres containing above 4% CO₂ with 15–20%O₂ caused a retardation in the softening of kiwifruit. This effect increased as the CO₂ content of the atmosphere increased from 4 to 10%, but additional CO₂ above 10% had no further effect on fruit firmness. Low O₂ (2–3%) with 3–5% CO₂ further delayed the rate of kiwifruit softening and increased storage life up to 3–4 months beyond normal air-storage life. Although controlled-atmosphere storage increases storage life of kiwifruit, the magnitude of the effect was found to vary from year to year. Contamination of the storage atmosphere by as little as 0.1 μl^?1 ethylene severely reduced the effectiveness of controlled-atmosphere storage in maintaining kiwifruit firmness, even at 0°C.     

1-MCP处理对不同采收成熟度‘徐香’猕猴桃保鲜效果的影响

以‘徐香’猕猴桃为试材,研究了4个采收期(盛花期后1301、381、46和154 d)1-MCP(1-甲基环丙烯)浓度为0.5μL/L处理24 h后,在(2±1)℃下贮藏后的保鲜效果。结果表明:1-MCP能够显著降低‘徐香’果实低温贮藏过程中呼吸速率、乙烯释放速率,延缓果实硬度、可滴定酸的下降以及可溶性固形物的上升;4个采收期的1-MCP处理果实出库后均能正常后熟,但品质和保鲜效果存在差异,其中Ⅱ、Ⅲ期处理果实在贮藏期结束时保持较高的硬度、可滴定酸和VC含量,并且110 d时失重和腐烂率较低;货架期末硬度、糖酸比相对较高,失重率和腐烂率较低。由此推断‘徐香’猕猴桃盛花期后138~146 d采收品质好,此时的1-MCP处理效果最佳。     

钾对猕猴桃果实品质与贮藏的影响

为提高猕猴桃果实品质与耐贮性,以7年生美味猕猴桃品种米良1号(Actinidiadeliciosacv.Miliang-1)为试材,进行果实生长发育期施钾处理对果实品质与贮藏性能影响的研究。结果表明:适量施钾能提高果实硬度及可溶性固形物与维生素C含量,降低果实含酸量,提高果实耐贮性。在0-4℃贮藏条件下,以株施纯K2O80g+叶面喷施0.3%硫酸钾处理果实贮藏效果最佳,贮藏73d时,其软果率最低(15.56%),果肉硬度最高(0.27MPa)。同时果实维生素C含量的下降趋势较为平缓,果实贮藏寿命延长。贮藏6个月时,株施纯K2O80g+叶面喷施0.3%硫酸钾处理的果实好果率(68.89%)明显高于对照果实(0)。     

Polygalacturonase and β-galactosidase activities in Hayward kiwifruit as affected by light exposure,maturity stage and storage time

Softening process and total antioxidant activity were evaluated in kiwifruit differently exposed to light intensity and harvested at two different times (October 10 and November 14). Fruit was stored for 2 months at 0 °C (S1) and then maintained for a week at ambient temperature (S2). The results showed that fruit harvested later presented a faster softening rate during storage than fruit harvested earlier, even if antioxidant activity did not change. Light-exposed fruit showed higher flesh firmness than that of shaded ones. Polygalacturonase activity was higher in kiwifruit maintained for a week at ambient temperature after cool storage and, in particular the highest value was recorded in fruit harvested later. The behaviour of β-galactosidase was different: it did not show changes in fruit harvested later and significantly decreased in light- and shade-exposed fruit harvested earlier.     

猕猴桃幼果期钙处理对果实贮藏和品质的影响

以中华猕猴桃品系湘酃８０－２为试材，在幼果期进行浸钙处理。结果表明：不同钙处理能不同程度地延长猕猴桃果实贮藏期，其中以０.５％Ｃａ_２（ＮＯ_３）_２处理对果实贮藏与品质的综合效果最好；０．５％Ｃａ（ＮＯ_３）_２＋ １００ ｍｐ·ｌ~(－1)萘乙酸能显著提高果实硬度与贮藏性能。     

冷激处理对香蕉后熟软化及相关酶活性的影响

 以‘巴西’香蕉(Musa nana‘Baxi’) 为材料, 研究了冷激处理对果实常温下后熟软化的影响。结果表明, - 20 ℃冷空气处理2.5 h明显延迟了后熟软化; 同时也延缓了多聚半乳糖醛酸酶(PG)和淀粉酶活性上升, 进而抑制了果胶和淀粉的降解, 对维持香蕉硬度起重要作用。     

钙处理对白凤桃果实冰温贮藏后细胞壁代谢物质的影响

以白凤桃为材料,研究了生长期和采后喷钙(1%CaCl2+0.1%Vc混合液)对冰温贮藏后果实细胞壁代谢物质的影响。结果表明,钙处理能较长时间地维持果实的硬度,生长期喷钙和采后喷钙的果肉中钙质量分数比对照分别高34.3%和3%。高钙质量分数的果实在货架期期间可减少果实中可溶性果胶和松弛结合型多糖的质量分数,这可能与细胞壁水解酶纤维素酶和果胶甲酯酶活性较低有关。说明生长期钙处理对冰温贮藏后白凤桃果实硬度的保持效果较好,在生产中使用生长期喷钙处理,可以达到延长白凤桃果实货架期的目的。