大久保桃的催熟条件研究

本文研究了冷藏后的大久保桃适宜的催熟方式、温度和时间对桃果实和软白桃罐头感官品质和理化指标的影响,并分析了原料利用率。结果表明：大久保桃采用打孔的PE袋包装,催熟效果较好,此时桃的腐败指数和褐变指数低,风味浓郁;有效冷藏18d内的大久保桃,30℃催熟3d后,生产的软白桃罐头感官和理化指标均达到国标要求;原料利用率均保持在83．31％以上。该研究为软白桃罐头加工中的桃催熟处理提供了技术依据。     

大久保桃的催熟条件研究

本文研究了冷藏后的大久保桃适宜的催熟方式、温度和时间对桃果实和软白桃罐头感官品质和理化指标的影响,并分析了原料利用率。结果表明:大久保桃采用打孔的PE袋包装,催熟效果较好,此时桃的腐败指数和褐变指数低,风味浓郁;有效冷藏18 d内的大久保桃,30℃催熟3 d后,生产的软白桃罐头感官和理化指标均达到国标要求;原料利用率均保持在83.31%以上。该研究为软白桃罐头加工中的桃催熟处理提供了技术依据。     

不同工艺条件对保鲜大久保桃罐藏制品风味的影响

研究了经MA贮藏的大久保桃在不同贮藏期出库后,在罐藏加工过程中不同工艺条件对制品风味的影响。试验结果表明,罐藏大久保桃制品的原料七成熟时采收,于0℃下采用MA贮藏25～40d;加工前升温后熟24～30h能够增强制品的桃香气;贮藏时间对桃香气有一定影响,但预煮时间、桃仁和桃仁水对增强桃香气效果均不显著。      

壳聚糖及其复配对大久保桃常温贮藏特性的影响

在常温贮藏条件下利用抗坏血酸、柠檬酸、迷迭香提取物与壳聚糖复配不同保鲜剂对大久保桃失重率、腐烂率、L*值、维生素C含量、可滴定酸含量、还原糖含量、可溶性固形物含量、果肉硬度等贮藏特性指标的影响,比较不同保鲜剂复配的贮藏保鲜效果。试验结果表明,4 g/L抗坏血酸+15 g/L壳聚糖溶液浸渍涂膜、4 g/L迷迭香+15 g/L壳聚糖溶液浸渍涂膜这两组处理的保鲜效果最为明显,协同增效保鲜作用突出。     

水杨酸保鲜大久保桃初探

大久保桃采收后分别用浓度为0．1、0．3、0．5、1．0、1．5g／L的水杨酸溶液浸泡20min,然后分别于室温（1997,30～34℃,6d;1998,25～28℃’C,7d）和冷库中（1997,2±2℃,4周;1998,10±2℃,3周）贮藏。两年的实验结果表明：0．1和0．3g／L的水杨酸较为适宜,可抑制桃腐烂,延长贮藏期,对果实品质无不良影响,并能保持贮藏于低温下果实的硬度;处理浓度过高时,则会使果实受到伤害,造成表皮褐斑,加速腐烂。     

间歇升温对冷藏桃果实品质的影响

研究了间歇升温（２５～２８℃）对大久保桃果实冷藏期间（２±１℃）及货架期品质的影响。结果表明：间歇升温处理对果实可溶性固形物的含量无影响，阻止了可滴定酸的下降及固酸比的上升，保持了果实的风味；间歇升温还促进果皮中叶绿素和类胡萝卜素的丧失，使果皮亨特“Ｌ”“ａ”值和着色指数增加；但间歇升温也降低果实硬度，升温２４和３６ｈ的果实硬度显著低于对照和升温１２ｈ的果实，而后两者发生的严重冷害使其失去了商品价值和食用价值。总之，适当的间歇升温既可使桃果实避免冷害，又可保持果实良好的色泽和风味。     

采收期对“大久保”桃贮藏期间果肉褐变的影响

以不同采收期的大久保桃为试材,分别研究其在冷藏期和货架期的酚类物质含量和多酚氧化酶(PPO)、过氧化物酶(POD)活性的变化,探讨其对果实褐变的影响。结果表明:采收期越早,酚类物质含量和多酚氧化酶、过氧化物酶活性越高,果肉褐变越严重,适时延迟采收可以有效减轻果肉褐变。八成熟(7月22日采摘于河北辛集市)桃果肉褐变程度最低。     

羧甲基壳聚糖涂膜对大久保桃保鲜及货架品质的影响

以N,O-羧甲基壳聚糖为主要涂膜材料对大久保桃进行保鲜实验,经0~1℃贮藏49d及20℃货架3d后研究果实的生理变化、冷害症状和感官品质。结果表明,与对照相比,涂膜处理能有效的维持桃果较低的呼吸强度,减少果实的腐烂和褐变,保持硬度和固酸比,减轻果肉组织伤害,降低果实冷敏感性,提高贮后品质。     

羧甲基壳聚糖涂膜对大久保桃保鲜及货架品质的影响

以N,O-羧甲基壳聚糖为主要涂膜材料对大久保桃进行保鲜实验,经0¹℃贮藏49d及20℃货架3d后研究果实的生理变化、冷害症状和感官品质。结果表明,与对照相比,涂膜处理能有效的维持桃果较低的呼吸强度,减少果实的腐烂和褐变,保持硬度和固酸比,减轻果肉组织伤害,降低果实冷敏感性,提高贮后品质。      

采收期对“大久保”桃贮藏期间果肉褐变的影响

以不同采收期的“大久保”桃为试材,分别研究其在冷藏期和货架期的酚类物质含量和多酚氧化酶(PPO)、过氧化物酶(POD)活性的变化,探讨其对果实褐变的影响。结果表明：采收期越早,酚类物质含量和多酚氧化酶、过氧化物酶活性越高,果肉褐变越严重,适时延迟采收可以有效减轻果肉褐变。八成熟(7 月22 日采摘于河北辛集市)桃果肉褐变程度最低。     

Characterization of polyphenol oxidase and peroxidase from peach mesocarp (Prunus persica L. cv. Babygold)

The two enzymes involved in enzymatic browning reactions—polyphenol oxidase (PPO) and peroxidase (POD)—were extracted from peach fruit mesocarp. PPO was mainly located in the membrane fraction and was in its latent state. However, POD activity was found in the soluble fraction. The kinetic characterization of PPO and POD was carried out with a natural substrate (chlorogenic acid) and with a non‐physiological substrate. Under native isoelectric focusing (IEF), several PPO isoenzymes were present in the pH range 5.4–5.8. A partially denaturing sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE) showed the presence of two active bands with apparent molecular masses of 49 and 50 kDa. A totally denaturing SDS‐PAGE indicated the presence of a single polypeptide with a molecular mass of 60 kDa, as revealed by western blot. POD was also analyzed by IEF, showing the presence of two strongly basic isoenzymes, which were resolved by cationic native PAGE into two different bands. Copyright © 2007 Society of Chemical Industry     

气调冷藏对牦牛肉保鲜效果的影响

生鲜牦牛肉食用品质好,深受消费者喜爱,但是在常规冷鲜贮藏过程中易变质,造成牦牛肉品质下降,甚至无法食用。为延长生鲜冷藏牦牛肉的贮藏期,并改善其在冷藏过程中的食用品质,该文采用气调辅助冷藏法对新鲜牦牛肉进行贮藏。通过比较新鲜牦牛肉在不同O2、N2和CO2的组合下失重率、pH值、挥发性盐基氮含量、菌落总数的变化,以及牦牛肉在不同气体组合下的保鲜期,结果发现,当O2、N2和CO2体积比为15∶75∶10时,气调辅助保鲜的牦牛肉品质较优。在该气体组合下,新鲜牦牛肉能在0℃~4℃条件下贮藏7 d仍然保持较好的品质,继续保藏7 d^18 d牦牛肉品质出现下降;贮藏25 d后,牦牛肉不能食用。表明气调辅助冷藏能较好地延长新鲜牦牛肉的冷藏品质保持时间。     

壳寡糖(COS)涂膜对冷藏水蜜桃的保鲜效果

分别用1%、2%壳寡糖(COS)及1%壳聚糖(CTS)对"白花"水蜜桃(Prunus persica)进行涂膜,探索2种涂膜对冷藏[(3±1)℃)]水蜜桃的保鲜效果。结果表明:CTS涂膜对果实呼吸强度的抑制作用较为明显,贮藏过程中没有出现明显的呼吸高峰,且在贮藏10 d后呼吸强度均小于其他组;2%COS涂膜处理可有效保持果实的硬度和可溶性固形物含量,且对抑制果实的相对电导率、丙二醛(MDA)的升高以及多酚氧化酶(PPO)也具有一定的调节作用。     

The effects of 1-methylcyclopropene on peach fruit (Prunus persica L. cv. Jiubao) ripening and disease resistance

In order to learn how 1‐methylcyclopropene (1‐MCP) affects ripening and disease‐resistance of peach fruit (Prunus persica L. cv. Jiubao) after harvest, they were treated with 1‐MCP and some were inoculated with Penicillium expansum. Treating peach fruit with 0.2 μL L^?1 of 1‐MCP at 22 °C for 24 h effectively slowed the decline in fruit firmness. The minimal concentration of 1‐MCP able to inhibit fruit softening was 0.6 μL L^?1. Changes in other parameters related to peach ripening, such as content of soluble solids, total soluble sugar, titratable acidity, soluble pectin and ethylene production were also significantly reduced or delayed by 1‐MCP. Repeated treatment of peach with 1‐MCP resulted in more effective inhibition of ripening. Post‐harvest decay of peach fruit was reduced by treatment with 1‐MCP and disease progress in fruit inoculated with P. expansum was reduced. The activities of phenylalanine ammonialyase, polyphenoloxidase and peroxidase in the inoculated fruit were also enhanced by 1‐MCP.     

冬枣保鲜技术的研究进展

冬枣是我国山东沾化、陕西大荔、河北黄骅等地区的一种主要经济作物,因其具有丰富的营养以及脆爽的口感,深受人们的喜爱;此外其产量大,价格实惠,市场占有率高,是一种常见的季节性水果。本文对冬枣保鲜技术进行了概述和总结,并从物理、化学和生物三个角度就冬枣的保鲜技术进行系统论述,其中重点阐述了气调保鲜和涂膜保鲜技术的应用和研究现状。文章为冬枣保鲜技术的进一步发展提供参考,同时为其他枣类及其制品的保鲜提供借鉴,进一步促进了食品行业的进步和发展。     

Polyphenoloxidase activity and polyphenol levels in organically and conventionally grown peach (Prunus persica L., cv. Regina bianca) and pear (Pyrus communis L., cv. Williams)

Polyphenoloxidase (PPO) activity and total polyphenol content were tested in organically and conventionally grown whole fruits, peach (Prunus persica L., cv. Regina bianca) and pear (Pyrus communis L., cv. Williams), in order to evaluate the existence of a relationship between these parameters and of differences between fruits obtained with the two cultivation practices. Organic fruits were obtained on three different grounds: subterranean clover (sample A), spontaneous weed cover (sample B) and tilled (sample C). From the latter soil, the conventionally grown fruits were produced. All organic peach samples showed a highly significant (P<0.001) increase in polyphenols (mg equivalents of tannic acid/100 g fresh sample) compared with conventional peaches, while, of the three organic pear samples, samples B and C displayed an increased polyphenol content with respect to the conventionally grown sample (P<0.05). Activity of PPO (U.E./100 g fresh sample), extracted in appropriate conditions and tested towards 1 mM chlorogenic and caffeic acid, was significantly higher in most of the organic peach and pear samples analyzed with respect to the conventional samples.     

热处理对红贵妃芒果贮藏品质及保鲜效果的影响

研究采后50℃热水处理10、15和20min对红贵妃芒果果实贮藏品质及某些生理性状的影响。结果表明:与对照相比,热水处理能显著抑制贮藏期间红贵妃芒果果实硬度、可滴定酸(TA)含量和VC含量的下降,延缓病情指数、总可溶性固形物(TSS)含量的上升,维持较高的SOD活性,抑制MDA的积累,从而改善了红贵妃芒果的贮藏品质,延缓了果实的成熟与衰老。综合结果认为10min和15min热水处理的效果较好。