Changes in Volatile Components of Stored Tangerines and Other Specialty Citrus Fruits with Different Coatings

ABSTRACT: Shellac and wax-based citrus coatings were applied to Fallglo, Robinson, Sunburst, Dancy and Murcott tangerines, Nova and Orlando tangelos, and Temple oranges. Flavor volatiles were measured before and after storage. Concentrations of ethyl acetate, ethyl butyrate, isopentanol and 2-methyl-3-buten-2-ol increased markedly for fruit with shellac-based coatings, and were highly correlated with ethanol content, but at different ratios for the different varieties. The concentration increases were relatively less for fruit coated with the wax-based coatings, and suggest that high-gloss shellac and resin-based coatings are not appropriate for tangerines.     

出口柑桔中双甲脒及代谢物残留量测定

柑桔样品中双甲脒及代射物在酸性条件下回流水解成2，4－二甲基苯胺，正己烷提取，酸，碱反复液－液分配净化，七氟丁酸酐将2，4－二甲基苯胺衍生成2，4－二甲苯七氟丁酰胺，用配有电子俘获检测器的气相色谱仪测定，外标法定量。     

Characterization of chemicals mediating ovipositional host-plant finding byAmyelois transitella females

Ovipositional host-finding in the navel orangeworm,Amyelois transitella (Walker), is brought about by an in-flight response to host odors. Wind-tunnel studies of the response of gravid females to almonds showed that this response is mediated primarily by long-chain fatty acids, particularly oleic acid and linoleic acid. Evidence for the behavioral activity of fatty acids is based on the fact that: (1) behavioral activity of almond oil was concentrated in a single liquid chromatographic fraction whose composition was predominantly long-chain fatty acids, (2) behavioral activity was lost when either almond oil or the active fraction of that oil was treated with diazomethane, (3) full activity was elicited by a selective extraction of free fatty acids from crude almond oil, and (4) upwind response by females was elicited by a blend of synthetic oleic and linoleic acids, albeit at a level less than that elicited by almond oil. Five fatty acids identified from the almond oil were: myristic acid (1%), palmitic acid (16%), stearic acid (3%), oleic acid (58%), and linoleic (22%). Attraction to various combinations of synthetic acids was observed only when oleic acid was present, and oleic acid elicited upwind flights to the source when presented alone; however, short-range responses were enhanced by the addition of linoleic acid, which elicited no long-range orientation by itself. Despite significant levels of attraction to synthetic blends, the percentage of females flying to the source was lower than that flying to acidulated almond oil, the best natural attractant tested. Thus, although longrange response may be mediated primarily by a blend of oleic and linoleic acids, additional and as yet unidentified components must also play an important role. Long-range chemically modulated host finding in this and other generalist plant feeders is discussed with respect to current models of the evolution of host finding, and it is argued that suggestions that long-range host finding should be correlated with narrowness of host utilization are logically flawed and are not supported by our current understanding of specific examples of host finding.     

微润灌溉对脐橙生理生态参数的影响研究

为探明微润灌溉对脐橙生长过程中生理生态参数的影响,对微润灌溉、常规灌溉和雨养灌溉3种灌溉方式下的脐橙叶片最大光合速率(Amax)、叶片呼吸(Rd)、表观初始量子效率(α)、光补偿点(Lcp)、叶片的比叶面积(SLA)等生理生态参数进行了测定和对比分析.研究结果表明,在其他条件相似的情况下,采用微润灌溉的方式对脐橙叶片Amax、Rd、α、SLA的促进作用最为明显,常规灌溉次之,雨养灌溉下值最低.叶片的Lcp在微润灌溉方式下最低,常规灌溉和雨养灌溉下的该值依次递增.     

Effects of nitric oxide on the alleviation of postharvest disease induced by Penicillium italicum in navel orange fruits

The present study evaluated the effects of 15 μL L^-1 nitric oxide (NO) on the fruit defence response of ‘Newhall’ navel orange. The decay rate of NO-treated navel orange fruits was significantly lower than that of control fruits during storage at 20 °C storage (P < 0.05). Treatment with NO suppressed the increase in disease incidence and lesion area in orange fruits inoculated with Penicillium italicum (P. italicum); significantly increased the activities of phenolic metabolism-associated enzymes and pathogenesis-related (PR) proteins, including polyphenoloxidase (PPO), phenylalanine ammonia-lyase (PAL), β-1,3-glucanase (GLU) and chitinase (CHT); and enhanced the activities of key enzymes, including 4-coumarate: CoA ligase (4CL), cinnamate-4-hydroxylase (C4H) and chalcone isomerase (CHI) in the phenylpropanoid pathway. The contents of total phenolics, flavonoids and lignin were also higher in NO-treated fruits than in control fruits. The findings suggest that exogenous NO could induce disease resistance against P. italicum in navel orange fruits.     

一种基于近红外光谱快速鉴别染色橙的新方法

本文应用近红外光谱仪(NIRS)测定染色橙样品的光谱数据,采用多种方式对光谱数据进行预处理,用主成分分析法(PCA)对不同染色橙样品进行聚类分析并获得染色橙的近红外光谱数据的主成分,在此基础上建立了偏最小二乘(PLS)回归模型,并根据均方根校准误差(RMSEC)和相关系数(R2)对模型性能进行评价。结果表明,主成分分析可以快速鉴别染色橙样品,模型识别率达到94%。将主成分分析(PCA)与偏最小二乘(PLS)相结合建立的回归模型,均方根校准误差(RMSEC)为0.26,决定系数R2为0.96,模型效果较好。表明利用近红外光谱鉴别染色橙是可行的,这为染色橙的鉴别提供了一种快速无损的新方法。     

基于图像原理脐橙分拣技术装置设计的研究

为了实现对脐橙的形状和大小分类快速检测,本文设计了一种简易机械装置与图像识别技术相结合的分类器;并应用MATLAB软件编程技术,实现了对样本图像背景的去除、边缘的提取、形状和大小的判断,从而自动实现脐橙外形与大小的有效分类。     

Molecular Mass and Solubility Changes in Pectins during Storage of Satsuma Mandarin Fruits (Citrus unshiu Marc.)

Soluble pectins in satsuma mandarin fruits stored at 5°C were investigated by High Performance Gel Filtration chromatography. Pectins isolated from the flavedo, albedo, membranes and juice sacs were separated into four fractions. The hydrochloric acid soluble pectin fraction in each part was the highest and decreased slightly while the water-soluble pectin increased slightly. The avergae molecular weights of the fractionated soluble pectins in juice sacs were nearly constant but those in flavedo, albedo and membranes decreased as storage time increased. The ratios of higher molecular weight of water soluble and ammonium oxalate-soluble pectins in all the four parts and those of hydrochloric acid soluble pectin in flavedo and membranes decreased as ratios of lower molecular weight fractions increased.     

Proton spin–spin relaxation time of peel and flesh of navel orange varieties exposed to freezing temperature

Proton spin–spin relaxation times (T₂) of peel (albedo and flavedo) and juice sacs (flesh segments) of navel oranges were measured at 10 MHz using a Bruker Minispec PC 110 NMR spectrometer. The oranges were subjected to chilling (5 °C) and freezing (−7 °C) temperatures for 20 h and warmed to room temperature before peeling for T₂ measurements. The exposure to chilling or freezing temperature did not affect the T₂ values of peel, but freezing caused an appreciable decrease (∼15%) in the T₂ values of flesh segments of the varieties of navel oranges studied. When the peel was exposed to −20 °C, the T₂ showed a drastic reduction suggesting that the peel did not freeze at −7 °C. The possible cause of reduction in the T₂ values when exposed to freezing temperature may be damage to the juice sac membrane and leakage of juice out of the sac. The difference in the T₂ values between juice sacs of freeze-affected and normal oranges can potentially be used for detection of freeze-damaged fruits. Copyright © 2005 Society of Chemical Industry