电子鼻在餐厨废弃油脂掺假判别中的应用

为牟取暴利,不法商贩将餐厨废弃油脂掺入正常商品油中销售,这提高了餐厨废弃油脂分析检测的难度。鉴于此,笔者采用电子鼻系统对掺入不同比例餐厨废弃油脂的花生油进行检测,并结合主成分分析(PCA)和线性判别式分析(LDA)等方法,建立电子鼻的响应值与餐厨废弃油脂掺入比例之间的数学模型。结果表明,电子鼻系统中W1W、W2W、W5S、W2S和W1S传感器对餐厨废弃油脂掺入比例较为敏感。在较低掺入比例时(5%),W2S、W1S传感器信号峰值的下降值与样品中餐厨废弃油脂含量存在良好的线性关系(R2值分别为0. 988和0. 997)。而利用PCA和LDA分析也可对纯花生油与掺入餐厨废弃油脂的花生油实现定性鉴别。本研究表明,利用电子鼻系统判别花生油中餐厨废弃油脂掺假情况具有较强的可行性。     

低温贮藏过程中溶质和硬质桃冷害发生的生理差异

该试验以溶质型桃品种(中油桃13号、春美和中油桃4号)和硬质型桃品种(中油桃18号、中桃9号和白如玉)为试材,分析桃果实在4℃低温贮藏过程中的品质变化以及乙烯释放规律,探索不同肉质桃果实冷害的发生机制。结果表明:(1)硬质型桃果实的冷害症状主要表现形式是果肉发生褐变,而溶质型桃的冷害症状以果肉木质化和絮败为主。(2)相对室温贮藏而言,短时间冷藏可以抑制溶质型桃果实内源乙烯的释放,但长时间低温冷藏会导致冷害发生,刺激乙烯释放量迅猛攀升;长时间的低温贮藏也会诱导硬质型桃内源乙烯的释放;在低温贮藏期间,毛桃品种果实乙烯释放高峰会比同种肉质类型的油桃品种推迟5～10 d,毛桃相较于油桃对低温的耐受性更强。(3)溶质型桃果实采后软化迅速,但其果实硬度下降速率在低温下受到明显抑制,在冷藏后期还维持在15N上下,而硬质型桃果实硬度在低温和常温贮藏期间受影响较小。(4)不同肉质类型桃果实的可溶性固形物含量在贮藏期间变化幅度均不大。研究发现,不同肉质型桃受到冷害的症状和乙烯释放的模式均不相同,该结果为不同质地的桃果实合理低温贮藏提了供理论依据。     

桃果实发育阶段肉色形成与类胡萝卜素的变化分析

为了分析不同肉色类型桃果实发育过程中类胡萝卜素成分的变化特点及其颜色差异形成的因素,选择‘半斤桃’(红肉)、‘图八德’(黄肉)、‘正姬’(白肉)桃品种为试材,采用紫外分光光度计和高效液相色谱法(HPLC)对桃果实类胡萝卜素及其组分含量进行定性定量分析.结果显示:(1)桃果实的主要类胡萝卜素成分为叶黄素、玉米黄素、β-隐黄质、α-胡萝卜素和β-胡萝卜素.(2)随着果实的发育,‘半斤桃’和‘正姬’的类胡萝卜素总含量逐渐降低,而‘图八德’则是先降低后上升,且明显高于前二者;3种类型桃果实的叶黄素均逐渐降低,果实成熟时接近0;玉米黄素呈先降后升的趋势,果实成熟时达到最大值;‘半斤桃’和‘正姬’的β-隐黄质、α-胡萝卜素和β-胡萝卜素呈逐渐下降的趋势,而‘图八德’的β-隐黄质含量先升后微降最后上升、α-胡萝卜素和p-胡萝卜素含量则逐渐增加,且均在果实成熟时达到最大值.(3)‘图八德’成熟果实中的类胡萝卜素总含量达到最大值,其中β-胡萝卜素含量最高,占5个成分之和的75.99％.研究表明,桃果实肉色形成与类胡萝卜素的含量与成分有着紧密的联系,尤其是其中的β-胡萝卜素含量.     

基于电子舌电子鼻分析红糖风味的差异性

目的：运用电子鼻、电子舌对不同品牌红糖风味进行检测区分，建立一种有效鉴别不同品牌、等级、产地红糖的方法。方法：对红糖感官评定结果进行等级一致性检验；运用电子舌自带软件对数据进行主成分分析，运用电子鼻自带软件对数据进行主成分分析、传感器区分度分析及线性判别分析；并利用DPS对电子舌数据进行方差分析及最小显著差异（LSD）法多重比较，对电子鼻数据进行方差分析；建立滋味雷达图观察不同红糖样品对传感器响应强度的差异性。结果：电子舌、电子鼻能够区分不同品牌、等级、产地的红糖，各红糖样品滋味差异主要是丰富性、咸味，香气成分差异主要是氮氧化合物、甲烷等短链烷烃、有机硫化物和无机硫化物；感官评定等级一致性检验结果也显示不同红糖样品的差异性显著。结论：电子舌、电子鼻技术可用于区分不同品牌、产地、等级的红糖，为红糖品质鉴别提供技术支持。     

金菠萝品种果实香气成分和特征香气研究

采用固相微萃取-气相色谱质谱联用法研究了金菠萝品种果实不同部位果肉、中柱和果皮的香气成分,并利用香气值确定了不同部位的特征香气。结果表明:各部位香气组成不同,果肉和中柱部位以酯类为主,果皮部位以萜烯类为主。己酸乙酯和己酸甲酯是果肉和中柱部位含量较高的成分,(Z)-β-罗勒烯是果皮部位含量最高的成分。4-甲氧基-2,5-二甲基-3(2H)呋喃酮和癸醛是果皮香气贡献较大的成分,而2-甲基丁酸乙酯、4-甲氧基-2,5-二甲基-3(2H)呋喃酮和己酸乙酯是果肉和中柱香气贡献较大的成分。金菠萝品种果肉和中柱的香气值与果皮差异较大,且香气值主要集中于果肉。     

番茄果实不同发育阶段香气成分组成及变化

以陕西杨凌地区主栽的番茄品种'金棚1号'为试验材料,通过固相微萃取和GC/MS联用技术,对番茄果实不同成熟阶段的香气成分及其组成变化进行了研究.结果表明,'金棚1号'番茄果实共检测到54种香气成分,主要成分为醛类、酸类、醇类、酮类、酯类、酚类等.在果实的不同发育阶段,香味组分及其含量差异较大.醛类物质在绿熟期相对含量较高,为45.87%,在半熟期、硬熟期、完熟期的相对含量分别为12.65%、16.62%、17.15%,其中C6醛在绿熟期占43.7%,完熟期占15.27%,为醛类物质的主要成分;酸类物质含量在4个发育时期中先上升后下降,在半熟期含量达到最高,为15.2%,在完熟期酸类物质含量下降,为6.93%;酮类物质在完熟期含量达到最大,为18.27%;在绿熟期检测到4种重要的番茄特征香气物质,半熟期检测到5种番茄特征香气物质,硬熟期和完熟期各检测到6种番茄特征香气物质.说明随着果实的成熟,特征香气物质种类增多.     

猕猴桃品种果实性状特征和主成分分析研究

为深入了解猕猴桃不同品种(系)的果实性状与其倍性的相关性,本研究对国家猕猴桃种质资源圃保存的44个栽培品种(系)进行了果实性状分析,结果表明,44个栽培品种(系)的果实性状具有丰富的遗传多样性并且果实重量、果面毛被、果肉颜色和质地、果实维生素C含量、果实后熟天数和软熟果硬度、果实成熟期等与品种(系)倍性呈显著相关。对相关性状采用主成分分析表明,果实成熟时间、果肉质地、果面毛被和果实后熟天数、果肉颜色是区分品种(系)的主要特征。由于品种(系)的倍性与主要性状特征关联,品种(系)按倍性相对聚类,且二倍体品种(系)群和六倍体品种(系)群间无重叠,而四倍体品种(系)群与相邻的二倍体和六倍体品种(系)群均有一定重叠。     

果树果实的风味物质及其研究

果树果实风味和芳香物质是果实的主要组成成分,对于果实品质具有重要影响。有关果实风味和芳香物质的研究一直是果树研究领域的重点。为更好地了解果实风味和芳香物质及相关研究进展,本文对果树不同树种与品种的芳香物质、特征效应化合物、糖和酸含量、糖酸比、多酚物质以及栽培、采收、贮藏条件等果实风味物质含量与组分的影响因素进行了较全面的介绍。     

电子鼻技术在快速检测小麦矮腥黑穗病菌中的应用

由小麦矮腥黑穗病菌(TCK)引起的小麦矮腥黑穗病是我国重要的检疫性病害,为明确电子鼻技术在快速检测小麦矮腥黑穗病菌方面的可行性,利用电子鼻对含有TCK和小麦光腥黑穗病菌(TFL)不同冬孢子数(50g小麦种子中冬孢子数分别为0、100、101、102、103、104、105)的小麦进行了检测,采用主成分分析法(PCA)和线性判别法(LDA)进行数据分析。结果发现,这2种分析方法均可将不含TCK冬孢子的小麦和含TCK冬孢子的小麦区分开来,而且通过LDA分析,可将TCK冬孢子含量为100、101、102及103以上的处理区分开来。另外,通过PCA分析,可将TCK与TFL区分开来。此结果为电子鼻技术在快速检测小麦矮腥黑穗病菌中的应用奠定了基础。     

5种新疆苹果资源的果实品质性状比较与评价

选择5种果皮和果肉颜色不同的新疆苹果地方特色资源克孜阿尔玛、卡拉阿尔玛、阿克阿尔玛、伊犁野苹果、柠檬海棠,以栽培品种富士为对照,通过果实外观品质、内在品质、营养品质和香气品质4个方面的指标进行品质精细化评价,并考察了红肉苹果果肉花青苷合成途径相关基因的表达情况,以明确新疆苹果地方资源不同果实品质指标的差异,为新疆苹果地方资源的合理利用提供资料。结果表明:(1)5种特色资源均为中、小果型苹果,其中红肉品种克孜阿尔玛的外观品质优于栽培品种富士,而柠檬海棠外观品质指标均处于最低水平。(2)阿克阿尔玛的糖、酸含量均显著低于富士,柠檬海棠的酸含量高于富士及其他品种。(3)伊犁野苹果的果肉硬度显著高于富士,而红肉资源品种的果肉硬度均低于富士,肉质松软、不耐储运,但其总酚、类黄酮含量最为丰富,抗氧化能力最强,均显著高于栽培品种富士。(4)香气品质中,红皮资源卡拉阿尔玛的挥发性物质种类及含量最为丰富,其含量高于最低的栽培品种富士近2倍,红肉资源的挥发性物质含量最低;红肉资源的挥发性物质以醇类为主,而红皮资源卡拉阿尔玛、伊犁野苹果和柠檬海棠以醛类物质为主。(5)主成分分析显示,各个新疆苹果地方资源营养、香气品质等综合品质表现为:克孜阿尔玛卡拉阿尔玛阿克阿尔玛富士伊犁野苹果柠檬海棠。(6)红肉苹果的果肉花青苷合成途径相关基因表达分析表明,其果肉花青苷积累过程中的关键基因是UFGT。     

Development of Ty1-copia retrotransposon-based SSAP molecular markers for the study of genetic diversity in peach

Sequence-specific amplified polymorphism (SSAP) technology is a novel, anchored PCR approach derived from AFLP, which amplifies the region between a transposon insertion and an adjacent restriction site and have higher levels of polymorphism. In the current study, we developed 16 SSAP markers based on the long terminal repeat (LTR) sequences of Ty1-copia retrotransposons in the peach and used them for DNA profiling of 52 individual peaches: 44 peach cultivars and 8 ornamental peaches. These primer combinations produced a total of 1,553 fragments and 1,517 polymorphic bands with a polymorphism percentage of 97.7%. Furthermore, the Shannon's information index of each primer combination ranged from 0.1593 to 0.4456. Neighbor-joining analyses revealed two main genetic clusters, corresponding to the fruit flesh types: (A-1) MF (melting flesh) with clingstone and ornamental peaches; (A-2) MF with freestone and NMF (non-melting flesh) with clingstone. Finally, cluster analyses revealed that all ornamental peaches are closely related to the MF with clingstone peach cultivars. The application of these primer combinations identified using SSAP will facilitate future cultivar identification and germplasm management in peaches.     

Changes in the Volatile Flavor Constituents of Citrus sinensis (L.) Osbeck During Storage

The methods of GC with fused silica capillary column, its Kovats retention index of GC and GC-MS-DS etc. We were used to study the aromatic compounds of the peel essential oil of Citrus sinensis (L.) Osbeck and aromatic concentrates of fruit flesh. 29 chemical constituents from the peels and 40 chemical constituents from the fruit flesh were identified. The trace constituents α-sinensal 0.01% and β-sinensal 0.01% are the special aroma ones for Citrus sinensis. At the same time, the changes flavor components in Citrus sinensis peels and fruit flesh during storage were also explored.     

The involvement of 1-aminocyclopropane-1-carboxylic acid synthase isogene, Pp-ACS1, in peach fruit softening

Ethylene promotes fruit ripening, including softening. The fruit of melting-flesh peach (Prunus persica (L). Batsch) cultivar 'Akatsuki' produces increasing levels of ethylene, and the flesh firmness softens rapidly during the ripening stage. On the other hand, the fruit of stony hard peach cultivars 'Yumyeong', 'Odoroki', and 'Manami' does not soften and produces little ethylene during fruit ripening and storage. To clarify the mechanism of suppression of ethylene production in stony hard peaches, the expression patterns of four ethylene biosynthesis enzymes were examined: ACC synthases (Pp-ACS1, Pp-ACS2, and Pp-ACS3) and ACC oxidase (Pp-ACO1). In the melting-flesh cultivar 'Akatsuki', Pp-ACS1 mRNA was dramatically induced after harvesting, and a large amount of ethylene was produced. On the other hand, in stony hard peaches, Pp-ACS1 mRNA was not induced during the ripening stage, and ethylene production was inhibited. Since Pp-ACS1 mRNA was induced normally in senescing flowers, wounded leaves, and wounded immature fruit of 'Yumyeong', Pp-ACS1 was suppressed only at the ripening stage, and was not a defect in Pp-ACS1. These results indicate that the suppression of fruit softening in stony hard peach cultivars was caused by a low level of ethylene production, which depends on the suppressed expression of Pp-ACS1.     

八个贵州地方桃品种果实甜酸风味品质分析

为了评价贵州地方桃品种果实的甜酸风味品质,以主栽桃品种‘燕红’作对照,采用高效液相色谱法测定了贵州8个地方桃品种的果肉糖酸组分及含量。结果表明:(1)8个地方桃品种果肉中糖主要由蔗糖、葡萄糖、果糖和山梨醇组成,其中蔗糖的平均含量最高(55.62 mg/g),约占总糖的71.30%,但变异系数仅为17.92%;8个地方桃品种中,‘米桃’的葡萄糖与果糖含量差异较大,其果糖/葡萄糖的比值为1.21,而其它7个品种的葡萄糖与果糖含量相近。(2)8个地方桃品种果肉中有机酸主要由苹果酸、柠檬酸、奎宁酸和莽草酸组成,其中苹果酸含量最高,约占总酸的60.61%,但在‘白花桃’果实中有机酸含量以奎宁酸为主。(3)对8个地方桃品种果实的糖酸组分进行主成分分析发现,苹果酸含量和山梨醇含量的载荷系数分别为0.910和0.897,说明它们是影响果实甜酸风味的主导因素,且对改善果实的甜酸风味品质具有重要作用。8个贵州地方桃果实的甜酸风味分别为:‘黄腊桃’为甜,‘血桃’、‘青桃’、‘镇远桃’、‘红枫桃’为酸甜,‘白花桃’、‘西桃’和‘米桃’为酸。     

Effect of abscisic acid (ABA) on sugar accumulation in the flesh tissue of peach fruit at the start of the maturation stage

Experiments were conducted on¹⁴C-sorbitol, fructose, and glucose uptakeinto flesh discs, and sorbitol efflux from thediscs, with and without ABA application toexamine the effect of abscisic acid (ABA) onsugar accumulation in peach fruit flesh at thestart of the maturation stage in relation tomembrane transport. Total uptake of¹⁴C-sorbitol, fructose, and glucose intoflesh discs was effectively promoted by ABA ata concentration of 10^–5 M. PCMBS(p-chloromercuribenzensulfonicacid)-sensitive uptake, which was considered ascarrier-mediated uptake, of sorbitol into thediscs was clearly stimulated by ABA at10^–5 M, compared with glucose andfructose uptake. Sorbitol efflux from the discsacross the tonoplast was restricted by ABA at10^–5 M. ABA application todeveloping fruit increased sugar accumulationin the fruit. Estimated ABA concentration inthis fruit was approximately 10^–5 M. These results indicate that sugar accumulationin peach fruit flesh is stimulated by ABA at aconcentration of 10^–5 M both invitro and in vivo. ABA stimulatesuptake of sugars, especially sorbitol, into theflesh by enhancing carrier-mediated transportpossibly across both tonoplast and plasmamembrane.     

A comparative study of melting and non-melting flesh peach cultivars reveals that during fruit ripening endo-polygalacturonase (endo-PG) is mainly involved in pericarp textural changes, not in firmness reduction

Peach softening is usually attributed to the dismantling of the cell wall in which endo-polygalacturonase (endo-PG)-catalysed depolymerization of pectins plays a central role. In this study, the hypothesis that the function of endo-PG is critical for achieving a melting flesh fruit texture but not for reducing fruit firmness was tested by comparing pericarp morphology and endo-PG expression and localization in melting (MF) and non-melting flesh (NMF) fruit at successive stages of ripening. MF Bolero, Springbelle, and Springcrest, and NMF Oro-A and Jonia cultivars were analysed. Both MF and NMF fruit were left to ripen on the tree and reached a firmness of <10 Newtons (N). The image analysis of pericarp tissues revealed that during softening the loss of cell turgidity was a process common to mesocarp cells of all MF and NMF fruit and was clearly visible in peaches with a firmness of less than ～20?N. In contrast, the loss of cell adhesion was a feature exclusively observed in ripe MF fruit pericarp. In this ripe fruit, large numbers of endo-PG isoforms were highly expressed and the enzyme localization corresponded to the middle lamella. As a consequence, wide apoplastic spaces characterized the pericarp of ripe MF peaches. In contrast, no loss of cell adhesion was observed in any NMF fruit or in unripe MF peaches. Accordingly, no endo-PG was detected in unripe NMF fruit, whereas few and poorly expressed enzyme isoforms were revealed in ripe NMF and in unripe MF peaches. In this fruit, the poorly expressed endo-PG localized mainly in vesicles within the cytoplasm and inner primary cell wall. On the whole the results suggested that endo-PG function was needed to achieve melting flesh texture, which was characterized by wide apoplastic spaces and partially deflated mesocarp cells. Conversely, endo-PG activity had no critical influence on the reduction of fruit firmness given the capacity of NMF peaches to soften, reaching values of 5-10?N. As in tomato, the change of symplast/apoplast water status seems to be the main process through which peach fruit regulates its firmness.