不同钾肥组合对烤烟质体色素及降解产物的影响

采用田间试验,以普通钾肥为对照,研究了缓释钾肥及其与普通钾肥、黄腐酸钾的配施对烤后烟叶质体色素及其降解产物的影响.结果表明:T1(普通钾肥)和T2(缓释钾肥)均不利于降低烤后烟叶叶绿素含量,T2处理两种等级烟叶质体色素降解物质总量均低于T1处理,而T3处理(普通钾肥+缓释钾肥)显著降低了两种等级烟叶叶绿素含量,提高了中部叶质体色素降解物质总量,却降低了上部叶质体色素降解物质总量和类胡萝卜素含量;T4处理(普通钾肥+缓释钾肥+黄腐酸钾)能降低两种等级烟叶叶绿素含量、提高上部叶类胡萝卜素含量,其上部叶质体色素降解物质总量高于其他各处理,中部叶质体色素降解物质总量仅低于T3处理,此外上部和中部叶中分别有12种和8种类胡萝卜素降解产物含量高于其他各处理.故综合看,T4是最优的施钾处理.     

成熟期淹水对烤烟石油醚提取物、主要化学成分及致香物质含量的影响

以烤烟云烟97为材料,采用田间试验研究了成熟期不同淹水时间处理对烤烟石油醚提取物、主要化学成分及致香物质含量的影响。结果表明,在不同淹水处理后,烤烟中部叶石油醚提取物、总糖、还原糖、烟碱、钾、氯含量以及钾/氯低于对照,而总氮和氮/碱高于对照;其中总糖、烟碱含量降幅达到44.06%和48.52%,总氮含量升幅达到47.64%。大多数致香物质含量和致香物质总量及不同种类致香物质含量都有不同程度的降低,致香物质中以新植二烯降幅最大达到52.15%,4种致香物质种类中以苯丙氨酸类和类西柏烷类致香物质下降最为明显,分别达到34.75%和31.90%。在各淹水处理中,以淹水5d对烤烟烟叶品质影响最大,说明成熟期淹水时间越长,对烟叶品质形成越不利。     

氮、磷、钾肥配施对烤烟化学成分和致香物质含量的影响

田间试验以烤烟(Nicotiana.tabacum.L.)品种K236为材料,研究了氮、磷、钾肥配施对烤烟化学成分和致香物质含量的影响。结果表明,不施肥处理烟叶内在化学成分协调性差,致香物质总量及不同种类致香物质含量都较低;单施氮、磷、钾一种肥料或任意两种肥料配施可以不同程度改善烟叶化学成分,提高烟叶中类西柏烷类和类胡萝卜素类致香物质含量;而氮、磷、钾配施处理烟叶的化学成分协调,致香物质总量和不同种类致香物质含量高。表明平衡施肥是改善烟叶化学成分,提高烟叶香气质量的基础。     

施用生物钾肥后减少化学钾肥对烤烟致香物质和评吸质量的影响

采用大田试验研究了施用生物钾肥后减少化学钾肥施用量对烤烟致香物质和评吸质量的影响.结果表明,施用生物钾肥后减少化学钾肥不会降低烟叶中主要致香物质含量和总致香物质含量,以减少化学钾肥14％的处理烟叶总致香物质含量和主要致香物质含量较高;施用生物钾肥后减少化学钾肥处理烤烟评吸质量较好,经济效益较高.但研究也发现,上述结果具有不稳定性,因此,针对不同烟区生物钾肥的研制和施用还有待于进一步的研究.     

下部鲜烟叶摘除数量对烤烟品质及经济性状的影响

为了明确重庆烟区下部鲜烟叶摘除数量对烤烟化学成分、香气物质、等级结构及经济性状的影响,本研究选用‘云烟97’品种,研究打顶期摘除下部0片(CK)、2片(T1)、3片(T2)和4片(T3)烟叶后对烤烟化学成分、香气物质、等级结构及经济性状等的变化特征。结果表明,随着下部叶片摘除数量的增加,中上部烟叶淀粉、总氮和烟碱含量有显著提高的趋势,钾素含量显著降低;中上烟叶的糖碱比和钾氯比与摘除叶片数呈负相关关系,氮碱比与摘除叶片数呈正相关关系;中部叶以摘除3片处理(T2)的致香物质含量最高,上部叶以摘除2片处理(T1)的致香物质含量最高。摘除下部叶片后烟叶等级结构和经济效益有不同程度提高,其中以T2处理最为显著,其次是T1处理,T3处理的效果最差。因此,综合考虑化学成分、香气物质、等级结构和经济效益等认为,在重庆武隆生态条件下的中等肥力土壤上处理下部鲜烟叶时以摘除3片叶为宜。     

稀土肥不同施用方式对烟草品质的影响

采用大田试验,设置了CK(常规施肥)、T1(常规施肥+稀土肥基施)、T2(常规施肥+稀土肥灌根)和T3(常规施肥+稀土肥叶面喷施)四个处理,研究了稀土肥不同施用方式对烤后烟叶化学成分的协调性、提高光合色素和香味物质的含量的影响。结果表明,叶面喷施稀土肥明显提高了烤后烟叶中蛋白质等含氮化合物和钾的含量,调节了糖碱比和钾氯比,协调化学成分;明显增加了烟叶中叶绿素和各类中性致香物质的含量。表明在常规施肥基础上,叶面喷施稀土肥能明显提高烟叶品质。     

不同温湿度发酵条件对晒黄烟中性致香物质的影响（简报）

为探讨不同温湿度发酵条件对宁乡晒黄烟中性致香物质的影响,选取上部叶和中部叶,在4种温湿度发酵条件下发酵30d,利用气质联用法测定中性致香物质含量的变化。结果表明,所测6类中性致香物质在发酵过程中均有不同程度增加,其中赖百当类转化产物增加最多,其次为棕色化反应产物、类胡萝卜素转化产物、类西柏烷类转化产物、苯丙氨酸转化产物,新植二烯略有降低。不同温湿度发酵条件下,以中温高湿的发酵条件在20～24d中性致香物质增幅较大,而中温低湿或低温中湿条件下中性致香物质缓慢增加,拉长了发酵时间,高温中湿不利于生成致香物质的积累,同时内含物消耗较多。     

不同施肥和灌溉组合对烤烟化学成分和香气质量的影响

以烤烟(Nicotiana tabacumL.)品种吉烟9号为材料,通过田间试验研究了不同施肥和灌溉组合对烤烟化学成分、香气成分含量、组成及其作用机理的影响。结果表明,N∶P2O5∶K2O为1∶2∶3和限量灌溉组合使烟叶的糖碱比和氮碱比均较适宜,蛋白质含量较低,化学成分较为协调,苯丙氨酸类、棕色化产物类和类胡萝卜素类致香物质含量较高,改善了烟叶的综合品质,表现为香气质纯净、香气量较足、杂气较少、刺激性较低、余味舒适、烟气浓度大、燃烧性好等,能较好满足延边烟区烤烟的生长发育,有利于提高烟叶香气质量。     

有机无机肥配施对烤烟质体色素及其降解产物的影响

通过田间试验研究有机无机肥不同配施比例对烤烟质体色素及其降解产物的影响.结果表明,在同一部位中,施用有机肥4个处理的叶绿素、类胡萝卜素含量比不施用有机肥处理的高,且均达到显著水平,CK3(100%芝麻饼肥)叶绿素含量最高,T2(50%无机肥+50%芝麻饼肥)类胡萝卜素含量最高,但在类胡萝卜素与叶绿素比值上,T2最高,CK3最低;在新植二烯、类胡萝卜素降解产物含量和质体色素降解产物总量方面,除T3(25%无机肥+75%芝麻饼肥)的中部叶以外,所有施用有机肥处理在各部位中三者含量均有不同程度的增加,其中下部叶:T1(75%无机肥+25%芝麻饼肥)的新植二烯和质体色素降解产物总量、T2的类胡萝卜素降解产物含量最高;中、上部叶:T2的三者的含量均最高.因此,50%无机肥+50%芝麻饼肥对烤烟质体色素及其降解产物的含量影响最大,尤其是上部叶.     

不同施氮条件对烤烟打顶前后代谢及物质积累的影响

采用大田试验研究了不同施氮条件对烤烟打顶前后碳氮代谢、苯丙烷类代谢关键酶活性及其相关物质积累的影响。结果表明: 不施氮下(N0), 打顶前烟叶碳氮代谢关键酶活性较低, 而苯丙氨酸解氨酶活性却较高, 这使得光合固定的碳优先向蔗糖、淀粉、多酚类积累; 单施化肥下(N1), 烟叶碳氮代谢关键酶活性高于N0处理, 但氮代谢强度大, 烟叶固定的碳较早地向烟碱积累, 色素含量高; 加施饼肥下(N2), 烟叶碳氮代谢关键酶活性高, 但代谢协调, 淀粉积累推迟, 色素含量较高, 而多酚类、烟碱积累量均处于N0与N1处理之间。烟株打顶后, 烟叶在短期内各关键酶活性都增强, 但其改变程度不一致, 烟叶内含物重新分配, 游离氨、色素含量递减, 而烟碱含量逐渐积累, N2处理烟碱含量最高。这说明施氮条件影响烟株碳氮代谢的协调程度, 影响烟叶物质积累的流向。因此, 通过控制施氮条件可以改变烟叶的代谢流向以至改变烟叶的质量风格特征。     

不同氮磷钾配施对烤烟石油醚提取物和中性致香物质的影响

田间试验以烤烟(Nicotiana tabacum L.)品种中烟100为材料,研究了N、P、K肥配施对烤烟石油醚提取物和致香物质含量的影响.结果表明:不施肥处理烟叶石油醚提取物含量和致香物质总量及不同种类致香物质含量都较低:N、P、K任意两种肥料配施均可以不同程度提高烤烟石油醚提取物和不同种类致香物质的含量;NPK的配施,随着施肥量的增加,烤烟石油醚提取物含量也随着增加,而致香物质含量呈现先增后减的抛物线现象.因此,N、P、K的合理配施是提高烤烟石油醚提取物和致香物质的重要措施.由田间试验结果获取的推荐施肥方案为N:P_2O_5:K_2O=1:2:3,其用量分别为75 kg/hm~2、150kg/hm~2和225kg/hm~2.     

拟穴青蟹软壳蟹与硬壳蟹营养品质和风味差异综合比较分析

为明确在最佳收集时间段内不同时间点的软壳蟹和硬壳蟹营养与风味物质的差异,本试验采用顶空固相微萃取(SPME)、气质联用(GS-MS)方法比较了拟穴青蟹硬壳蟹与蜕壳后0~48 h软壳蟹肌肉和肝胰腺2种组织中水分、灰分、氨基酸、矿物质元素、脂肪酸及挥发性物质含量。结果表明,软壳蟹2种组织在蜕壳0 h水分含量最高,硬壳蟹灰分含量显著(P<0.05)高于各时间点软壳蟹。除肝胰腺中胱氨酸和丙氨酸外,2种组织硬壳蟹其他氨基酸含量均高于软壳蟹,其中亮氨酸含量差异显著(P<0.05);在肌肉和肝胰腺组织中,分别有12和14种氨基酸含量均在蜕壳后6 h最高。软壳蟹2种组织Ca、Mg和Fe含量高于硬壳蟹,但差异不显著;蜕壳0 h 软壳蟹肝胰腺组织中Ca含量显著高于其他时间点(P<0.05)。蜕壳后24 h软壳蟹肌肉和0 h肝胰腺组织中∑PUFA均高于其他时间点。2种组织中挥发性物质包括烷烃类、醛类、酮类、醇类、芳香烃类、酯类、酚类和醚类化合物,总体相对含量有差异,但差异不显著。综上比较,拟穴青蟹软壳蟹蜕壳后0~6 h肝胰腺和肌肉比其他时间点更具营养、风味更加,是制取软壳蟹最佳时间。本研究结果为软壳蟹生产、营养和风味评价、市场价值评估提供了一定的参考。     

Bound amino acids in humic acids from arable cropping systems

We investigated the varying concentrations of bound amino acids in humic acids (HA) extracted from soils under both crop rotation and continuous cropping of rye. The experiment was created in 1957. Since then, winter rye had been grown continuously and also the sequence of the 7 yr rotation had been started: potato, spring barley, alfalfa, alfalfa, oil seed rape, winter rye, and winter rye. Soils were fertilized with NPK and manure. Continuous cropping of rye increased total acidity of soils and the contents of carboxylic and phenolic groups in HA. The total amounts of the bound amino acids in HA from soils under crop rotation were higher than from continuous cropping of rye. Fertilization with NPK increased the contents of bound amino acids more than manure. Neutral amino acids dominated in all samples of HA, and basic amino acids had the lowest concentrations. In both types of cultivation, glutamic acids, glycine, alanine, valine, and lysine dominated. The proline contents in HA from continuous rye cropping were higher than in HA from soils under crop rotation. The concentrations of β‐alanine and lysine were higher in HA from crop rotation indicating a higher microbial biomass since these compounds are typical constituents of bacteria cell walls.     

Changes in the volatile composition of a semihard ewe milk cheese induced by high-pressure treatment of 300 MPa

The effect of high-pressure (HP) treatment (300 MPa, 10 min) on the volatile profile of semihard ewe milk cheeses was investigated. The HP treatment was applied at two different stages of ripening (1 and 15 days; 3P1 and 3P15) and microbiota, proteolysis indexes (soluble nitrogen and total free amino acid content), and volatile compounds were assayed at 15, 60, 90, and 150 days of ripening. The intensity of odor and aroma of cheeses was also assayed. 3P1 cheeses presented the highest content of free amino acids and were characterized by the lowest amounts of aldehydes, ketones, short-chain free fatty acids, and terpenes and higher levels of ethanol and ethyl esters. 3P15 cheeses were characterized by the highest content of short-chain free fatty acids and pyruvaldehyde and the lowest abundance of secondary alcohols and were more similar to control cheeses than those HP-treated on the first day. Intensities of odor and aroma were not significantly influenced by the HP treatment. However, the panellists found some differences in 3P1 as compared with control and 3P15 cheeses in what they perceived as lower odor and aroma quality.     

Biosynthesis of strawberry aroma compounds through amino acid metabolism

The fate of amino acids in relation to aroma biogenesis was studied in strawberries using the in vitro growth approach. This fruit presented differences in the level of metabolization for different amino acids. Incubations of strawberries with L-isoleucine gave rise to an increase of fourteen compounds in this fruit aroma, either not detected previously or constituents of strawberry aroma. However, L-valine incubations did not provide a significant change in this fruit aroma. Strawberry feeding with L-isoleucine resulted in a 7-fold increase in the sum of 2-methylbutanoate esters, and a double production of 2-methylbutyl esters compared to those of control fruits. Around 94% of the ester increase corresponded to 2-methylbutanoates, with ethyl 2-methylbutanoate being the most representative compound (92%). On the other hand, among the 2-methylbutyl esters, comprising around 6% of total aroma volatiles increase, 2-methylbutyl acetate was the major compound (95%) arising from L-isoleucine strawberry feeding. The role of enzymatic activities within the amino acid metabolic pathway in strawberry fruits is discussed.     

不同类型生鲜鸡对白切鸡风味的影响

为研究不同类型的生鲜鸡加工的白切鸡在风味方面的差异,探讨能否用冷鲜鸡、冷冻鸡替代热鲜鸡制作白切鸡,以热鲜(约15℃)、冷鲜(0~4℃)和冷冻(-18℃)3种不同类型的雪山黄母鸡胴体为原料,进行不同处理后用传统制作工艺加工成白切鸡,通过测定处理后白切鸡的挥发性风味物质、pH值、有机酸含量、呈味核苷酸含量和游离氨基酸含量等研究其风味差异。结果表明,冷鲜4个处理组与热鲜2 h组、热鲜4 h组的肌苷酸(IMP)、总游离氨基酸含量无显著差异,但重要挥发性风味物质(如醛类)和丁二酸含量高于热鲜2 h组和热鲜4 h组;热鲜1 h组的IMP含量显著高于冷鲜处理组(P<0.05),但其重要挥发性风味物质含量低于大部分冷鲜组;冷冻60 d组和冷冻90 d组除己醛含量显著高于其他处理组,其他挥发性风味物质、滋味物质含量均较低。综上,冷鲜鸡和短期冷冻鸡在总体上可以替代热鲜鸡制作白切鸡,这为白切鸡工业化生产发展提供了理论支持。     

不同施氮水平对红花大金元烟叶香味物质和感官评吸质量的影响

【目的】 氮素施用水平主导着烟叶的氮素代谢,影响烟叶中有机酸、酚类、石油醚提取物、木质素等香味物质的含量,进而影响烟叶的感官评吸质量。探索不同氮素施用量对红花大金元 (简称红大) 烟叶香味物质和感官评吸质量的影响,以期为烤烟栽培中氮素的科学施用提供理论依据。 【方法】 2013 年在云南玉溪和大理烟区以烤烟红大为供试材料进行田间试验。设置施氮水平 0、45、90 和 135 kg/hm2 (分别以 N₀、N₁、N₂ 和 N₃ 表示),分析了烤烟香味物质和感官评吸质量指标。 【结果】 烟叶中挥发酸含量随施氮量的增加而显著提高,大理试验以 N₃ 处理含量最高,达到 0.13%;烟叶中高级脂肪酸总量和多元有机酸均以 N₂ 处理最高,玉溪分别为 19.71 和 82.65 mg/g,大理分别为 20.67 和 94.12 mg/g。烟叶中多酚含量在N₂ 水平最高,至 N₃ 时出现下降。烟叶石油醚提取物含量随施氮水平的提高而显著增加,玉溪和大理试验点 N₃ 处理含量分别为 6.25% 和 6.05%。烟叶木质素含量以 N₂ 处理最低,玉溪和大理试验点含量分别为 5.19% 和 5.42%。红大烟叶感官评吸总分均以N₂ 处理最高,玉溪和大理试验点的评分分别为 77.4 和 78.1。 【结论】 氮素施用水平中等时 (90 kg/hm2),烟叶挥发酸和石油醚提取物含量适中,高级脂肪酸和多元有机酸含量较高,酚类物质积累较多,木质素含量较低,烟叶各香味物质含量协调性较好,感官评吸时烟叶香气质、香气量、余味、杂气、劲头和评吸总分较高,烟叶品质优良。      

Temporal changes in aroma release of Longjing tea infusion: interaction of volatile and nonvolatile tea components and formation of 2-butyl-2-octenal upon aging

The temporal change in the headspace composition of an aroma model mimicking Longjing green tea aroma was studied in the presence of nonvolatile Longjing green tea constituents. Upon storage at 50 degrees C, the formation of 2-butyl-2-octenal was found, which increased with time. This enal was generated by crotonization of hexanal as demonstrated in model experiments. The formation of 2-butyl-2-octenal was also detected in Longjing tea infusions and Longjing tea leaves upon storage at 50 degrees C. The presence of nonvolatiles induced a strong decrease in aroma release. These effects were mainly due to catechins, major constituents of green tea infusion. Free amino acids, that is, glycine, contributed only to significantly decrease alpha,beta-unsaturated carbonyl aroma compounds, that is, 1-octen-3-one and geranial. Model reaction containing a mixture of 1-octen-3-one and glycine indicated on the basis of NMR and MS data the formation of the tentatively identified N-1-(3-oxo-octyl)glycine resulting from a 1,4-addition. The perceived aroma of green tea infusion is very likely to be affected by the formation of new aroma compounds and the changes in aroma release affected by interactions with tea nonvolatile components. This deserves further investigations on the sensory level.     

Flavoring components of raw monsooned arabica coffee and their changes during radiation processing

Volatile aroma principles, nonvolatile taste constituents (caffeine and chlorogenic and caffeic acids), and glycosidically bound aroma compounds of monsooned and nonmonsooned raw arabica coffee were analyzed using gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC). Among the most potent odor active constituents known to contribute to the aroma of the green beans, 3-isopropyl-2-methoxypyrazine, 3-isobutyl-2-methoxypyrazine, 4-vinylguaiacol, beta-damascenone, (E)-2-nonenal, trans,trans-2,4-decadienal, phenylacetaldehyde, and 3-methylbutyric acid were detected by GC-MS in both samples. A decrease in content of methoxypyrazines and an increase in 4-vinylguaiacol and isoeugenol resulted in a dominant spicy note of monsooned coffee. These phenolic compounds exist partly as their glycosides, and their release from the bound precursors during monsooning accounted for their higher content in monsooned coffee. A considerable decrease in astringent chlorogenic acid as a consequence of hydrolysis to bitter caffeic acid was noted in monsooned coffee. Radiation processing of nonmonsooned beans at a dose of 5 kGy resulted in an increased rate of monsooning. At this dose a quantitative increase in most of the aroma active components could be observed in all samples studied. Hydrolysis of chlorogenic acid to caffeic acid was noted in radiation-processed monsooned coffee beans irrespective of whether the treatment was carried out before or after monsooning. These changes were, however, not observed in irradiated, nonmonsooned coffee beans, suggesting an enzymatic rather than a radiolytic cleavage of chlorogenic acid. A rationale behind the mechanism of monsooning and radiation-induced enhancement of the monsooning process is discussed.