Influence of 1-methylcyclopropene on ripening,storage life,and volatile production by d'Anjou cv. pear fruit

d'Anjou cv. pear fruit (Pyrus communis L.) exposed at harvest to 0, 0.42, 4.2, or 42 micromol m(-)(3) 1-methylcyclopropene (1-MCP) for 12 h at 20 degrees C were stored at 1 degrees C for up to 8 months. After storage, half of the fruit was continuously exposed to ethylene (0.45 or 4-18 mmol m(-)(3)) for 7 days at 20 degrees C. All fruit treated with 1-MCP had lower respiration and ethylene production compared to untreated controls. Fruit quality changes were delayed following 1-MCP treatment, as was development of superficial scald and peel yellowing. The duration of 1-MCP-induced responses was dependent on 1-MCP treatment concentration. When 1-MCP-treated fruit began to ripen, softening and production of volatile compounds proceeded similar to that of untreated fruit. Post-storage ethylene exposure did not consistently stimulate ripening of fruit previously treated with 1-MCP. Efficacy of ethylene treatment depended on 1-MCP concentration and storage duration.     

Impact of 1-methylcyclopropene and methyl jasmonate on apple volatile production.

Climacteric Fuji apples were treated with 10 microL x L(-1) MCP (1-methylcyclopropene), 2 mmol x L(-1) MJ (methyl jasmonate), or a combination of 10 microL x L(-1) MCP and 2 mmol x L(-1) MJ. Fruit were kept at 20 degrees C for 15 days after treatment. Production of ethylene and other volatile compounds was measured prior to and 3, 7, 11, and 15 days after treatment. Ethylene production decreased 3 days following MJ treatment and then increased. MCP treatment alone or in combination with MJ inhibited ethylene production. MJ and MCP inhibited production of many volatile alcohols and esters. The production of individual alcohols and esters appears to be differentially inhibited by MJ or MCP. MJ and MCP inhibited not only production of alcohols but also formation of esters from alcohols.     

Influence of 1-methylcyclopropene and storage atmosphere on changes in volatile compounds and fruit quality of conference pears

Conference pears (Pyrus communis L.) were treated with 25 and 50 nL L(-1) 1-methylcyclopropene (1-MCP) at -0.5 degrees C for 24 h, then stored for up to 22 weeks in air (NA) and controlled atmosphere (CA). After 7 and 14 weeks of storage, fruits were retreated with 1-MCP. After 7, 14, and 22 weeks of storage, fruits were kept for up to 7 days at 20 degrees C in air for poststorage ripening. The effects of 1-MCP treatment declined with duration of storage in both storage atmospheres, indicating that retreatments had little additional effects on subsequent ripening. Ethylene production was lower and firmness was higher in 50 nL L(-1) fruits, while the 25 nL L(-1) dose was not very different from the control. Development of superficial scald was not prevented by 1-MCP treatments, but the severity of the symptoms was influenced. The 1-MCP effects were perceivable on texture (juiciness) and flavor. Control fruit and 25 nL L(-1) fruit reached their best sensory quality after 14 weeks of storage, while 50 nL L(-1) fruit reached the same sensory quality later, keeping a fresh flavor when the quality of control fruit declined and became watery or grainy. The fresh flavor in 50 nL L(-1) fruit was probably due to the presence below the odor detection threshold concentrations of the volatile compounds responsible for the "ripe pear" aroma, mainly of butanol and ethyl butanoate. CA prolonged or enhanced the effects of 1-MCP; 1-MCP cannot substitute for CA but can reinforce the CA effects.     

Effects of exogenous propylene on softening, glycosidase, and pectinmethylesterase activity during postharvest ripening of apricots

Apricots (Prunus armeniaca L. cv. Boccuccia spinosa) picked at the commercial ripening stage [soluble solids content (SSC) 12.6%] were left to reach full ripening in continuously humidified air at 20 degrees C. Changes in the rate of ethylene production, firmness, soluble solids concentration, and titratable acidity were measured. The alpha-D- and beta-D-glucosidases, alpha-L-arabinofuranosidase, alpha-D- and beta-D-galactosidases, beta-D-xylosidase, and alpha-D-mannosidase activities were assayed. To evaluate the influence of ethylene on glycosidase activity, propylene (500 microL x L(-1)) was applied to apricots for 24 and 48 h. In apricots ripened in air, ethylene production increased on the first day and exhibited a typical climacteric pattern. Good edible quality was reached in 5 days when SSC was at least 14% and acidity was between 1.1 and 1.2% (% malic acid). During postharvest ripening, alpha-L-arabinofuranosidase activity increased from 1.9 to 11.6 nkat until day 7. alpha-D-Galactosidase, alpha-D-mannosidase, and beta-D-galactosidase activity increased continuously but at a lower rate. beta-D-Xylosidase activity also increased, but the level of activity was lower than the other glycosidases assayed. Pectinmethylesterase (PME) decreased during the postharvest ripening, and propylene enhanced this pattern, by stimulating ethylene production. Even the activities of alpha-L-arabinofuranosidase, beta-D-xylosidase, alpha-D-mannosidase, and beta-D-galactosidase were greatly stimulated by the propylene treatment, which consequently induced rapid softening of the fruits.     

Effect of 1-methylcyclopropene on volatile emission and aroma in cv. Anna apples

The rapidly ripening summer apple cultivar Anna was treated with 0.1 micro L(-1) and 1 microL L(-1) 1-methylcyclopropene (MCP) at harvest and kept at 20 degrees C, or stored for 5 weeks at 0 degrees C and then transferred to 20 degrees C. Total volatiles were not reduced by treatment with 0.1 microL L(-1) MCP, but were 70% lower in fruits treated with 1 microL L(-1) MCP than in untreated fruits. Ethylene production was 50% and 95% inhibited by 0.1 microL L(-1) and 1 microL L(-1) MCP, respectively. The volatiles produced by fruit at harvest were predominantly aldehydes and alcohols, with some acetate esters as well as 2-methyl butyl acetate and beta-damascenone. During ripening, the acetate and butyrate esters increased greatly and alcohols and aldehydes decreased. MCP-treated apples retained more alcohols, aldehydes, and beta-damascenone volatiles than did untreated apples. Sensory evaluation found that control and 0.1 microL L(-1) treated apples developed more fruity, ripe, and overall aromas, but the preference was for the 1 microL L(-1) treated apples with a less ripe aroma.     

Microbial ethylene production and inhibition of methanotrophic activity in a deciduous forest soil

Production of C₂H₄, but not of CH₄, was observed in anoxically incubated soil samples (cambisol on loamy sand) from a deciduous forest. Ethylene production was prevented by autoclaving, indicating its microbial origin. Ethylene production gradually decreased from 4 to 12 cm soil depth and was not affected by moisture or addition of methionine, a possible precursor of C₂H₄. Oxidation of atmospheric CH₄ in soil samples was inhibited by C₂H₄. Ethylene concentrations of 3, 6 and 10 μl l⁻¹ decreased CH₄ uptake by 21, 63 and 98%, respectively. Methionine and methanethiol, a possible product of methionine degradation, also inhibited CH₄ oxidation. Under oxic conditions, C₂H₄ was consumed in the soil samples. Ethylene oxidation kinetics exhibited two apparent K_m values of 40 μl l⁻¹ and 12,600 μl l⁻¹ suggesting the presence of two different types of C₂H₄-oxidizing microorganisms. Methanotrophic bacteria were most probably not responsible for C₂H₄ oxidation, since the maximum of C₂H₄ oxidation activity was localized in soil layers (2-8 cm depth) above those (8-10 cm depth) of CH₄ oxidation activity. Our observations suggest that C₂H₄ production in the upper soil layers inhibits CH₄ oxidation, thus being one reason for the localization of methanotrophic activity in deeper soil layers.     

Effects of ethylene and 1-methylcyclopropene (1-MCP) on gene expression and activity profile of alpha-1,4-glucan-phosphorylase during banana ripening

Starch phosphorylases are enzymes that can use starch as substrate, and they are supposed to act in both in starch synthesis and degradation. This paper reports the effects of ethylene and 1-methylcyclopropene (1-MCP) on the degradation of starch and phosphorylase activity and gene expression. The results indicate that phosphorylase activity is induced during ripening and that it is associated with the onset of starch degradation. The regulation of banana phosphorylase activity is mainly dependent on gene expression, and the absence of ethylene perception by 1-MCP had a positive effect. However, this effect can be precluded by increased levels of ethylene, both autocatalytic and exogenous.     

Effect of jasmonates on ethylene biosynthesis and aroma volatile emission in Japanese apricot infected by a pathogen (Colletotrichum gloeosporioides)

The effects of the application of the jasmonic acid derivative n-propyl dihydrojasmonate (PDJ) on ethylene biosynthesis, volatile compounds, and endogenous jasmonic acid (JA) and methyl jasmonate (MeJA) were examined in Japanese apricot (Prunus mume Sieb.) infected by a pathogen (Colletotrichum gloeosporioides). The fruit were dipped into 0.4 mM PDJ solution before inoculation with the pathogen and stored at 25 °C for 6 days. The inoculation induced an increase in 1-aminocyclopropane-1-carboxylic acid (ACC), ethylene, JA, and MeJA. In contrast, PDJ application reduced the endogenous JA, MeJA, and ethylene production and expression of the ACC oxidase gene (PmACO1) caused by the pathogen infection. The lesion diameter with C. gloeosporioides decreased upon PDJ application. The alcohol, ester, ketone, and lactone concentrations and alcohol acyltransferase (AAT) activity increased in the pathogen-infected fruit, but were decreased by PDJ application. These results suggest that PDJ application might influence ethylene production through PmACO1 and that aroma volatile emissions affected by pathogen infection can be correlated with the ethylene production, which is mediated by the levels of jasmonates.     

Interactive responses of gala apple fruit volatile production to controlled atmosphere storage and chemical inhibition of ethylene action

Gala apples exposed to the ethylene action inhibitor 1-methylcyclopropene (1-MCP) for 12 h at 20 degrees C were stored at 1 degrees C in air or a controlled atmosphere (CA) maintained at 1 kPa O2 and 2 kPa CO2. Volatile compounds were measured after 4, 12, 20, and 28 weeks plus 1 or 7 days at 20 degrees C. Treatment with 1-MCP and then storage in air or CA or storage in CA without 1-MCP treatment reduced volatile production as compared to apples not treated with 1-MCP stored in air. The reduced production of esters, alcohols, aldehydes, acetic acid, and 1-methoxy-4-(2-propenyl)benzene was observed. Ester production by fruit stored in CA decreased throughout the storage period regardless of previous 1-MCP treatment. The production of esters, alcohols, aldehydes, acetic acid, and 1-methoxy-4-(2-propenyl)benzene by 1-MCP-treated fruit stored in air plus 7 days at 20 degrees C increased after 20 or 28 weeks of storage. Continuous exposure to 417 micromol m(-3) ethylene for 7 days at 20 degrees C after 12 or 28 weeks of storage stimulated production of many volatile compounds, primarily esters and alcohols, by fruit stored in CA or 1-MCP-treated apples stored in air. However, exposure to ethylene had no effect on the production of aldehydes or acetic acid.     

硅酸钠处理对杏品质和风味物质的影响（英）

硅酸盐作为一种安全有效的物质,已被广泛用于果蔬等采后病害的控制,为了研究其处理对园艺产品品质的影响,该文以兰州“大接杏”（Armeniaca vulgaris Lam. cv. Lanzhou Dajie）为试验对象,在室温（22±2℃）下使用硅酸钠（10 mmol/L）化学诱抗处理,探讨硅酸盐对杏果实品质,特别是挥发性风味物质的影响。结果表明,硅酸钠处理可延缓果实硬度的下降和腐烂率的升高,在贮藏结束后,其分别是对照组的1.95倍和58%。并能够减少贮藏过程中可滴定酸、可溶性固形物及Vc含量的下降,但对果实总糖含量的影响不显著。采用固相微萃取（SPME）结合气相色谱质谱联用（GC-MS）的方法分离鉴定了“大接杏”果实的香气成分,共分离鉴定出超过100多种挥发性成分。硅酸钠处理样挥发性物质的释放总量低于对照。同时,处理后的杏果还表现出醛类物质、萜类物质和β-紫罗兰酮的释放增大和酯类物质的释放减少的现象。与对照相比,该处理能够更好地保持杏果实良好的品质,是一种可行的杏果保鲜处理方法。     

1-MCP和壳聚糖处理保持红枣贮藏品质及其机理研究

以新疆灰枣为试材,研究纸片型1-甲基环丙烯（1-methylcyclopropene,1-MCP）与壳聚糖（chitosan,COS）处理在（0±1）℃条件下对灰枣品质及相关酶活性的影响。结果表明：至贮藏90 d时,与对照（CK）相比,1-MCP＋COS的腐烂率、失质量率分别降低53.4%、51.2%,可溶性固形物（total soluble solid, TSS）含量高出18.6%。抗氧化酶系统中的超氧化物歧化酶（superoxide dismutase, SOD）峰值水平提高58.2%,过氧化氢酶（catalase, CAT）峰值高出34.8%;贮藏结束时过氧化物酶（peroxidase, POD）活性是CK的1.98倍,抗坏血酸过氧化物酶（ascorbate peroxidase, APX）活性高出51.7%,差异显著（P＜0.05）。1-MCP、COS及1-MCP+COS处理均可不同程度地降低果实腐烂率、失质量率,保持较高的果实硬度和TSS含量,推迟呼吸高峰和乙烯释放速率高峰的到来并抑制丙二醛（malondialdehyde, MDA）的积累,抑制脂氧合酶（lipoxygenase, LOX）和多酚氧化酶（polyphenol oxidase, PPO）活性,显著提高抗氧化酶系统活性。其中1.50 μL/L纸片型1-MCP与1% COS复合处理对保持果实贮藏品质、延缓果实衰老、延长货架期最有利。     

Relationship of ethylene biosynthesis to volatile production, related enzymes, and precursor availability in apple peel and flesh tissues

Regulation of ethylene biosynthesis or action has a major effect on volatiles production in apples. To understand the biochemical processes involved, we used Greensleeves apples from a transgenic line with a high suppression of ethylene biosynthesis. The study was focused at the level of the aroma volatile-related enzymes, including alcohol acyltransferase (AAT), alcohol dehydrogenase (ADH), and lipoxygenase (LOX) and at the level of amino acids and fatty acids as aroma volatile precursors in peel and flesh tissues. In general, volatile production, enzyme activity levels, and precursor availability were higher in the peel than the flesh and were differentially affected by ethylene regulation. AAT enzyme activity showed a clear pattern concomitant with ethylene regulation. Contrarily, ADH and LOX seem to be independent of ethylene modulation. Isoleucine, an important precursor of aroma compounds including 2-methylbutanoate esters, showed a major increase in the peel during ripening and responded significantly to ethylene regulation. Other important aroma volatiles precursors, like linoleic and linolenic acid, showed an accumulation during ripening associated with increases in aldehydes. The significance of these changes in relation to aroma volatile production is discussed.     

1-MCP处理和气调包装对枸杞鲜果低温贮藏品质的影响

为比较1-甲基环丙烯(1-methylcyclopropene,1-MCP)处理和2种气调包装对枸杞鲜果保鲜的效果,研究了1.0μL/L的1-MCP处理、聚乙烯膜气调包装(polyethylene film modified atmosphere packaging,PEF-MAP)和硅窗膜气调包装(silicon gum filmMAP,SGF-MAP)对枸杞鲜果(2±1)℃下贮藏品质和生理特性的影响。结果表明,1-MCP处理可减轻枸杞果实贮藏末期感官酸腐味,但对可滴定酸和果皮颜色等没有显著影响(P>0.05)。聚乙烯膜气调包装和硅窗膜气调包装可保持果实可溶性固形物质量分数,提高固/酸比及表皮状况、香气、质地等感官品质,但加快了可滴定酸的下降,对颜色、感官液汁变化影响不明显(P>0.05)。在贮藏末期(第35天),3个处理分别可将枸杞果实腐烂率由46.7%降低至31.1%、8.9%和26.7%。气调包装对枸杞的贮藏效果好于1-MCP处理,其中,聚乙烯膜气调包装效果较佳,可将枸杞果实贮藏期延长14d。试验结果可为鲜食枸杞商业化贮藏提供参考。     

Assessment of the volatile composition of juices of apricot, peach, and pear according to two pectolytic treatments

The behavior of volatile compounds according to two enzymatic treatments applied during the manufacture of fruit juice is described. More than 80 compounds were detected of a wide range of chemical families (alcohols, aldehydes, ketones, terpenoids, esters, norisoprenoids, ...). Theaspirane and alpha-isophoron were tentatively identified for the first time in apricot and peach fruits. The enzymes used, for extraction or clarification of fruit juices, modified the polysaccharides separated by molecular weight and the content of soluble polysaccharides. This could indicate differences in the fruit juice matrix, which could be related to observed changes in the volatile profile. In apricot, the enzymes enhanced the juice in terpenes and norisoprenoids as varietal compounds. In peach and pear, the enzymes used did not favor the amount of lactones and decadienoate esters, the character impact compounds, respectively.     

1H nuclear magnetic resonance-based metabolomic characterization of wines by grape varieties and production areas

(1)H NMR spectroscopy was used to investigate the metabolic differences in wines produced from different grape varieties and different regions. A significant separation among wines from Campbell Early, Cabernet Sauvignon, and Shiraz grapes was observed using principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). The metabolites contributing to the separation were assigned to be 2,3-butanediol, lactate, acetate, proline, succinate, malate, glycerol, tartarate, glucose, and phenolic compounds by PCA and PLS-DA loading plots. Wines produced from Cabernet Sauvignon grapes harvested in the continental areas of Australia, France, and California were also separated. PLS-DA loading plots revealed that the level of proline in Californian Cabernet Sauvignon wines was higher than that in Australian and French Cabernet Sauvignon, Australian Shiraz, and Korean Campbell Early wines, showing that the chemical composition of the grape berries varies with the variety and growing area. This study highlights the applicability of NMR-based metabolomics with multivariate statistical data sets in determining wine quality and product origin.     

采后硅酸钠处理对贮藏期兰州“大接杏”果实品质和挥发性风味物质的影响

本文以兰州“大接杏”（Armeniaca vulgaris Lam. cv. Lanzhou Dajie）为试材,使用硅酸钠（10 mM）化学诱抗处理,以探讨其对杏果实品质,特别是挥发性风味物质的影响。结果表明,硅酸钠处理可延缓果实硬度、可滴定酸、可溶性固形物（SSC）和Vc含量的下降,但对果实总糖含量的影响不显著。采用固相微萃取（SPME）结合气相色谱质谱联用（GC-MS）的方法分离鉴定了“大接杏”果实的香气成份,共分离鉴定出超过100多种挥发性成份。硅酸钠处理样挥发性物质的释放总量低于对照,同时处理后的杏果还表现出醛类物质、萜类物质和β-紫罗兰酮的释放增大和脂类物质的释放减少的现象。     

基于机器视觉和近红外光谱技术的杏干品质无损检测

干果品质直接影响其市场销售。该研究以杏干为对象探讨用机器视觉和近红外光谱技术快速无损检测干果内外品质的方法。拍摄杏干4个不同位置的彩色图像,用基于区域骨架化的填充法分割杏干,提取每种角度下的面积。从100个正常杏干样本中随机挑选75个为校正集,25个为预测集,用多元线性回归对杏干的实际质量和4个面的面积建模,得到校正集和预测集相关系数分别为0.9374和0.9307,杏干质量分级的准确率为90%。提出用基于平均灰度的区域增长法提取杏干缺陷,缺陷检测的准确率为84.5%。采用SNV对杏干近红外光谱进行预处理,然后分别采用偏最小二乘法(PLS)、向后区间偏最小二乘法(biPLS)及联合区间偏最小二乘法(siPLS)建立杏干糖度预测模型。结果表明,当全光谱范围被划分为22个子区间,优选出区间[17、2、3、9、20、13、7、18、15、11、6],主因子数为10时建立的biPLS糖度模型性能最好。其校正集相关系数和校正均方根误差分别为0.8983和1.23,预测集相关系数和预测均方根误差分别为0.8814和1.46。研究表明,机器视觉结合近红外光谱技术能对杏干内外品质进行综合检测,也可为其他干果的品质检测提供借鉴。     

筛下物杂质对小麦微生物活动与储藏品质的影响

杂质类型与含量的控制是中国粮食流通面临的一个亟待解决的问题,选择性清除危害性较大的杂质,减轻或避免储藏过程中杂质导致的危害,旨在提高粮食储藏稳定性,减少储粮损失。该文在30℃、相对湿度为80%～90%储藏条件下,就筛下物杂质对小麦微生物活动及品质的影响进行了研究,结果表明：筛下物杂质通过其携带微生物间接影响小麦储藏品质。在适合霉菌生长的条件下,筛下物杂质可增加粮堆局部带菌量,并使其品质劣变;筛下物杂质携带霉菌越多,小麦品质变化越快。相关性分析可知：外部霉菌量、内部霉菌检出率与脂肪酸值呈显著正相关（r=0.799、0.602）,与发芽率、过氧化物酶活性呈显著负相关。由此可见,筛下物杂质对小麦储藏品质影响较大,在小麦入库前宜尽可能地将筛下物杂质除净以减轻或避免储藏过程中杂质对小麦储藏的危害,增加小麦储藏的稳定性。     

Relationships between volatile production, fruit quality, and sensory evaluation in Granny Smith apples stored in different controlled-atmosphere treatments by means of multivariate analysis.

Aroma compounds, quality parameters, and sensory evaluation of Granny Smith apples were analyzed after 3, 5, and 7 months of cold storage in three controlled-atmosphere (CA) treatments, in which oxygen and carbon dioxide were held at 1, 2, and 3%. During poststorage ripening, the apples were kept at 20 degrees C for 1, 5, and 10 days before analytical measurements were made. The highest volatile emission was obtained after 5 months of storage in all CA treatments, reaching its highest value when a low-oxygen CA (LO) was used. Ultralow-oxygen CA (ULO) showed the highest ability to maintain apple firmness. The correlation among analytical and sensory parameters suggests that ethyl 2-methylbutyrate, 1-butanol, pentyl acetate, and tert-butyl propionate are the aroma compounds with the highest influence in the sensorial score. Concerning CA treatments, LO and ULO appear to be very valuable technologies for maintaining the sensorial quality even after 7 months of storage.     

Influence of nitrogen levels and plant spacing on growth,productivity and quality of two inbred varieties and a hybrid of aromatic rice

A field investigation was conducted at the Indian Agricultural Research Institute's Research Farm during the kharif (wet) seasons of 2002 and 2003 in a split plot design with three replications, consisting of 27 treatments, namely, main plots: three varieties (PRH-10, Pusa Sugandh-3 and Pusa Basmati-1) and three plant spacings (20 × 10, 20 × 15 and 20 × 20 cm²) and sub-plots: three levels of nitrogen (0, 80 and 160 kg N ha^?1). The research results indicated that aromatic rice hybrid PRH-10 produced 33 and 6%, respectively, more grain yield than that of Pusa Sugandh-3 and Pusa Basmati-1. The appreciable higher grain yield of PRH-10 over Pusa Sugandh-3 and Pusa Basmati-1 was due to considerable improvement in most of the yield attributing characters. Application of 160 kg N ha^?1 recorded 23.7 and 26.1% more grain yield over no nitrogen application whereas it was 6.4 and 6.1% more over 80 kg N ha^?1, respectively, during first and second year of the experimentation. Wider plant spacing of 20 × 20 cm² and application of 160 kg N/ha recorded significantly higher hulling, milling and head rice recovery compared to closer spacing and zero nitrogen application.