目的 介绍采后果蔬呼吸代谢途径及其调控的研究进展,为采后果蔬生理生化及其贮藏保鲜技术研究提供一定的理论依据.方法 综述国内外采后果蔬呼吸关键代谢途径、酶、中间产物和保鲜技术对采后果蔬呼吸代谢途径的影响,总结采后果蔬呼吸代谢的产生机理及其受保鲜技术调控的影响.结果 总结了采后果蔬呼吸代谢途径中关键酶和中间产物的产生机制及其调控方法,归纳出利用保鲜技术控制采后果蔬的呼吸代谢途径可达到降低呼吸代谢的目的.结论 呼吸代谢作为采后果蔬主要的代谢方式,通过相应的物理、化学和生物保鲜技术对其进行调控,能够明显抑制褐变、冷害和品质下降的发生,由此可见,对呼吸代谢进行调控将在采后果蔬贮藏和销售方面起到重要作用.

Surface browning is the primary limiting factor for the shelf-life of fresh-cut apple. Hydrogen sulfide (H2S) treatment is known to effectively inhibit the browning, however, little is known about the underlying molecular mechanism. In the present paper RNA-Seq technology was used to analyse the transcript expression profiles of control and H2S treated fresh-cut apple immediately after treatment (C0 and S0) and 6 d of storage (C6 and 56) at 4 degrees C. The results identified 3782 and 1164 differentially expressed unigenes (DEGs) in S0 vs. C0 and S6 vs. C6, respectively. Expression of most DEGs related to antioxidant systems and energy metabolism was up-regulated after H2S treatment, whilst expression of genes encoding polyphenol oxidase, peroxidase, lipid-degrading enzymes, such as lipoxygenase and phospholipase D, was repressed. Further quantitative real-time PCR testing validated the reliability of our RNA-Seq results. We therefore propose that H2S treatment inhibited the surface browning of fresh-cut apple by regulating antioxidant, energy and lipid metabolism to maintain the membrane integrity of the plant tissue.

二氧化氯(ClO2)气体是国际上公认的安全、无毒绿色消毒剂,其具有杀菌性强、扩散性和穿透性好、不发生氯的替代反应、无毒副作用等优点,已在农业、食品、医药等领域应用广泛.近年来,ClO2在果蔬保鲜领域得到很好的应用,成为研究热点.本文论述了ClO2气体对采后果蔬中乙烯和呼吸、膜脂、苯丙烷类、能量等生理代谢及果蔬失水软化、外观和营养等贮藏品质方面的影响,并讨论了ClO2气体对果蔬致病、致腐微生物的杀菌机理及其杀菌效果,同时分析了ClO2气体在果蔬保鲜中的应用限制,最后,根据目前的应用研究现状对存在的问题进行总结,并对其未来的应用前景进行了展望,旨在为拓宽ClO2气体在果蔬保鲜领域的广泛应用提供参考.

清洗是鲜切果蔬加工过程中必不可少的环节,清洗不仅可以减少微生物数量,还可以去除果蔬经切分后流出的组织汁液,减缓褐变反应,降低营养成分损失,提高食用品质.本文综述了物理清洗、化学清洗和生物清洗技术通过物理或化学作用破坏微生物细胞壁、细胞膜和DNA等而导致其死亡的杀菌机理及其对鲜切果蔬中PPO和POD等褐变相关酶活的抑制作用以及这些技术对鲜切果蔬中Vc、叶绿素和固形物含量等营养物质的维持效果,同时还归纳了适合不同种类鲜切果蔬的清洗技术条件,提出了鲜切果蔬清洗技术的研究方向,以期为今后研究不同清洗技术对鲜切果蔬微生物与品质的影响提供理论依据.

以毛葱为研究对象,研究水煮、蒸制和油炸等不同烹饪方式处理对其总酚含量和抗氧化活性的变化.利用福林酚法测定总酚含量,采用DPPH自由基清除能力、ABTS自由基清除能力和还原能力3个指标评价抗氧化活性.结果表明:水煮、蒸制、油炸3种烹饪加工后毛葱的总酚含量均降低,烹饪处理降低了毛葱对自由基的清除能力,却提高了其还原能力.不同烹饪处理后总酚含量和抗氧化活性为:蒸制>水煮>油炸,且烹饪时间越长总酚含量越少,抗氧化能力越弱.

鲜切果蔬由于其营养、方便、安全等优点受到广大消费者的喜爱,然而果蔬鲜切后会引发微生物污染、组织软化、褐变和货架期缩短等一系列问题.为了使鲜切果蔬行业得到进一步的发展,对其保鲜技术的研究十分迫切.光电杀菌技术因其绿色安全、成本低廉、操作简单等优势而受到关注.本文主要针对光电杀菌技术中的紫外线、脉冲光、高压脉冲电场和发光二极管处理在鲜切果蔬保鲜中的杀菌机理、杀菌效果及产品品质的影响等进行论述,并对其目前在鲜切果蔬保鲜方面的研究进展进行了总结,以期为光电杀菌技术在鲜切果蔬保鲜中的应用提供参考.

Surface browning is the major limit for the shelf life of fresh-cut apples, and hydrogen sulfide (H2S) treatment can effectively inhibit the browning. However, the molecular mechanism on how fresh-cut apples respond to H2S was poorly understood. MicroRNAs (miRNAs) are a class of endogenous small noncoding RNAs, which regulate multiple crucial biological processes in almost all aspects of the life cycle. Herein, 12 small RNA libraries and one mixed degradome library were constructed from control and H2S-treated fresh-cut apples immediately after treatment (C0 and S0) and 6 d of storage (C6 and S6) at 4 °C. The results identified nine (three upregulated and six downregulated) and 10 (two upregulated and eight downregulated) differentially expressed miRNAs (DEmiRNAs) in S0 versus C0 and S6 versus C6, respectively. The target genes of DEmiRNAs were transcription factors and functional proteins. The miR156 targeting SPL, miR164 targeting NAC, miR319 targeting TCP4, GAMYB, and acyl-CoA-binding protein 4, and miR6478 targeting patatin-like protein 2 might play important roles in the browning inhibition of fresh-cut apples by H2S via regulating the ROS, phenylpropanoid, and lipid metabolism. The results give valuable information for further studying the role of miRNA in regulating browning processes and the underlying molecular mechanism of H2S treatment on browning inhibition.

AbstractThe influence of aqueous ozone (1.4 mg/L) treatment for 1, 5, and 10 min on the microbial growth and quality attributes of fresh‐cut cabbage during storage at 4°C for 12 days was evaluated. The pesticide residue removal effect of aqueous ozone treatment for 5 min was also determined. The results show that the growth rates of aerobic bacteria, coliforms, and yeasts were significantly inhibited (p < .05) by aqueous ozone treatment during storage; treatment for 10 min showed the greatest inactivation of bacteria, coliforms, and molds. Aqueous ozone stimulated initial respiratory metabolism compared with that of the control. Aqueous ozone treatments reduced ethylene production and improved the overall quality of fresh‐cut cabbage. In addition, the effect of aqueous ozone treatment for 5 min on the removal of trichlorfon, chlorpyrifos, methomyl, dichlorvos, and omethoate from fresh‐cut cabbage was greater (p < .05) than that of the control. These results indicate that aqueous ozone treatment for 5 min could be an economic and effective method to remove pesticide residues and enhance the storability of fresh‐cut cabbage.

鲜切果蔬因其方便、安全、营养的特点受到广大消费者的青睐,通常果蔬受到机械损伤后会发生酶促褐变、组织分解、产生异味等一系列复杂的初生、次生代谢生理变化,同时也产生了一些酚酸、黄酮类、单宁等酚类物质来抵御不良生物和非生物环境,这些抗性物质通过阻碍O2转化成O2-以及调节O2的总体水平来实现机体抗氧化的效果,从而阻碍机械损伤造成的一系列生物和非生物影响.该文综述了鲜切果蔬酚类物质的产生及调控的研究进展,为鲜切果蔬酚类物质的合成及其调控研究提供理论依据.

[目的]探索UV-C预处理后鲜切和鲜切后UV-C辐照两种方式对鲜切梨褐变的控制效果及其生理机制,为鲜切梨的贮藏保鲜以及扩大UV-C在果蔬方面的应用提供理论依据.[方法]以鲜切''皇冠''梨为研究对象,分别在鲜切前、后采用UV-C(有效波长254 nm)辐照处理5 min,分析在5℃贮藏过程中,两种方式UV-C处理后鲜切梨的褐变程度(BI)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)活性、总酚含量、抗氧化相关酶(超氧化物歧化酶(SOD)、过氧化氢酶CAT、抗坏血酸过氧化酶APX、谷胱甘肽还原酶GR)活性、H2O2和丙二醛(MDA)含量以及非酶抗氧化能力(DPPH、ABTS自由基清除能力和还原能力)的变化.[结果]与对照相比,两种UV-C处理均能显著抑制鲜切梨的褐变,其中鲜切后UV-C处理控制效果更好.两种UV-C处理均不同程度提高鲜切梨的PPO活性、降低PAL活性和总酚含量,同时提高鲜切梨的抗氧化酶活性以及非酶抗氧化能力,抑制了H2O2和MDA的积累.相关性分析显示,鲜切梨的BI值与CAT、APX和GR活性以及非酶抗氧化能力呈极显著负相关(P<0.01),与H2O2和MDA含量呈极显著正相关(P<0.01).[结论]UV-C处理主要通过提高鲜切梨的抗氧化防御能力从而延缓贮藏过程中的表面褐变,两种处理方式相比,鲜切后UV-C处理更能有效提高鲜切梨的抗氧化能力,对褐变控制效果更好.

The effects of aqueous ozone (AO) treatment on the firmness, cellwall polysaccharide content, enzymatic activity, and gene expression of cell wall-degrading enzymes were investigated in fresh-cut apple during cold storage. AO treatment (1.4 mg L-1 for 5 min) delayed degradation of cellwall polysaccharides to reduce softening of fresh-cut apple. Water-soluble pectin content increased more slowly, while protopectin content, 4% KOHsoluble fraction, and cellulose content decreased at a lower rate in AO-treated fresh-cut apple compared with the control. However, no significant influence was shown on the 24% KOH-soluble fraction. AO treatment promoted increased pectin methylesterase activity, and distinctly inhibited ?-galactosidase and ?-arabinofuranosidase activities during storage. Polygalacturonase activity was not affected by AO treatment. Meanwhile, AO maintained the intactness of cell walls through repression of Md?-Gal and Md?-Af transcript levels, thereby preserving the textural quality of fresh-cut apple during cold storage.

本文研究了芒果中所含的4种主要抗氧化物-没食子酸、芦丁、维生素C (Vc)、还原型谷胱甘肽(GSH)的抗氧化活性.应用体外试验法模拟芒果中的4种抗氧化物及其复配组合,通过分析各抗氧化物及其复配组合对羟自由基(·OH)、超氧阴离子(O2-·)、1,1-二苯基-2-苦基肼(DPPH)的清除能力大小来判断抗氧化能力的强弱.结果 表明,·OH的清除率最高的是没食子酸+芦丁+GSH+Vc复配组,达99％,清除率最低组为单一抗氧物Vc组,较最高组低27％;O2-·清除率最高的是GSH+Vc复配组,达87％,而没食子酸+GSH+芦丁的复配组对O2-·清除率最低只有4％;DPPH清除率最高组为芦丁+GSH复配组合,为35％,Vc+没食子酸复配组对DPPH的清除率最低,为2.50％.综上所述,抗氧化物的抗氧化性可单独发挥作用,也可能是组合式发挥叠加作用,对自由基清除效果最佳的是GSH+Vc.

The Variability Index Modified Rank Squared (VIMRS) nonparametric detector is introduced in this article. Depending on whether the background environment is homogeneous or not, VI-MRS can select Modified Rank Squared CFAR (MRS-CFAR), Greatest of Modified Rank Squared CFAR (GO-MRS-CFAR), or Trimmed Modified Rank Squared CFAR (TMRS-CFAR) to compute the threshold adaptively. The performance of the proposed detector is analyzed under the Swirling II target model in homogeneous and non-homogeneous environment by Monte-Carlo simulation. The results show that the proposed detection algorithm has better performance compared with Generalized Sign (GS) and Modified Rank Squared (MRS) detector.