Volatile compounds produced by fungi grown in strawberry jam

Fungi are most important micro-organisms spoiling jams and other fruit preserves. The volatile compounds produced by fungi can be used to detect fungal growth in food. The aim of this study was to identify volatile organic compounds indicating fungal growth in strawberry jam. Ten fungal strains isolated from jam, yogurt or indoor air were grown in strawberry jam and strawberry jam agar. The volatile compounds produced by fungi were separated, identified and quantified using gas chromatography and mass spectrometry. The most commonly produced volatile metabolites were 2-pentanone (produced by ten strains), 3-methyl-1-butanol (nine strains), 1,3-pentadiene (eight strains), ethanol (eight strains) and styrene (seven strains). From 17 to 5200 ng of these compounds were measured per g of moldy strawberry jam agar already after 2 days incubation. The results indicate that volatile fungal metabolites identified in this study could be used to detect fungal contamination of jam.     

基于离子迁移谱的花生霉变早期预警标示分子研究

花生作为我国主要的油料经济作物之一，在加工贮藏等环节极易受到黄曲霉菌的侵染而失去使用价值。挖掘黄曲霉菌污染发生早期预警标识分子对于花生霉变的早期监测预警具有重要意义。本研究采用气相色谱-离子迁移谱法对花生中黄曲霉侵染过程中的挥发性有机化合物进行分析，共检测到53种挥发性有机化合物，其中包含34种化合物单体及部分物质的二聚体，另外19种物质目前尚未定性分析。结果表明黄曲霉不同生长阶段产生的挥发性有机化合物具有较大差异。通过挥发性物质的指纹谱图观察侵染过程中各阶段挥发性物质的变化规律和相对含量的变化，根据特征峰图片库结果结合化学计量学方法可以对花生的早期霉变程度进行有效的区分。热图聚类分析和主成分分析比较不同化合物之间的差异性和相似性，结果表明不同侵染阶段挥发性有机化合物差异明显，具有明显区分度，其中己酸、2，3-丁二酮、2-己烯-1-醇-M、戊-1-醇-M和己醛可作为花生早期霉变的潜在生物标志物。本研究为仓储条件下花生霉变程度的早期预警监测体系的开发提供了有效的标识分子。     

Influence of the cultivation system in the aroma of the volatile compounds and total antioxidant activity of passion fruit

The aim of this study was to investigate the influence of the cultivation system on the volatile composition of the passion fruit and to determine the odoriferous contribution of the compounds for the aroma of the organic and conventional fruit, besides to assess the total antioxidant activity. The volatile compounds were isolated from dynamic headspace, separated by high-resolution gas chromatography and the odoriferous contribution to the passion fruit aroma was evaluated using the OSME technique. Total antioxidant activity was determined using the ABTS radical reaction. The organic and conventional passion fruit showed similar volatile profile, although some differences occurred. Ethyl 2-propenoate, 2-methyl-1-propanol, diethyl carbonate and ethyl hexanoate were threefold higher in the organic fruit while butyl acetate, hexanal, cis-3-hexenyl acetate and trans-3-hexenyl butanoate were threefold higher in the conventional fruit. Hexanoate and acetate esters, and saturated alcohols described as fruity, sweet, citrus and passion-fruit aroma showed the highest odorific intensity in the organic fruit. Furthermore, trans and cis-3-hexenyl acetate and alpha-copaene, alpha-terpineol, D-limonene, trans-beta-ocimene and delta-cadinene had higher contribution to the organic passion fruit aroma. On the other hand, unsaturated alcohols, beta-myrcene and beta-linalool described as grass, sulfur-like and passion-fruit aroma were higher in the conventional fruit. The organic passion fruit showed higher levels of total phenolic compounds and total antioxidant activity than the conventional fruit, suggesting that the cultivation system influenced the production of antioxidant bioactive compounds.     

基于GC-IMS分析不同成熟度百香果挥发性有机物的差异

本研究采用气相-离子迁移谱（Gas chromatography-ion mobility spectrometry,GC-IMS）对不同成熟度百香果的挥发性成分进行了分析,建立了一种快速区分不同成熟度果实风味差异的方法。GC-IMS共鉴定出33种挥发性有机物,主要包括醇类、酯类、醛类、酮类和萜烯类5大类。熟果（花后60 d果）和较熟果（花后50 d果）中挥发性有机物存在明显差异,熟果中多数挥发性成分的含量更高,包括DL-2-羟基-4-甲基戊酸乙酯、2-戊酮、乙酸丁酯、2-庚酮、α-蒎烯、(E,E)-2,4-庚二烯醛、苯甲醛、柠檬烯、β-罗勒烯、2-丁酮、丁酸甲酯、丁酸乙酯和乙酸乙酯等,而有少数挥发性物质在较熟果中含量更高,包括乙酸异戊酯和乙酸异丁酯等。GC-IMS能够快速检测和判别不同成熟度百香果风味特征和差异,本文研究结果可为百香果的采收和品质控制等提供科学依据和借鉴。     

不同护色处理的枇杷果酒挥发性风味成分对比

以万州大五星枇杷为研究对象,采用不同的护色工艺酿造枇杷果酒。分别采用液相色相仪、氨基酸自动分析仪与顶空固相微萃取（HS-SPME）结合气相色谱-质谱（GC-MS）联用技术检测不同果酒样品中有机酸、氨基酸及挥发性风味物质,并结合主成分分析（PCA）和聚类分析（CA）对其挥发性风味物质进行分析。结果表明,添加抗坏血酸、柠檬酸结合热处理的护色处理酿造枇杷果酒护色效果最佳,与未经护色处理样品相比,该护色处理有利于增加果酒中有机酸（苹果酸、柠檬酸、丁二酸）、氨基酸（苦味、芳香族及甜味氨基酸）含量;共检出挥发性风味物质38种,其中酯类、醇类、酮类、其他类物质分别增加2种、3种、1种、1种;PCA结果表明,不同枇杷果酒样品中主要挥发性风味物质为辛酸乙酯、乙酸苯乙酯、癸酸乙酯、苯乙醇等,聚类分析将样品聚集为三大类。     

西南地区不同产地松茸挥发性成分分析

用有机溶剂萃取-蒸馏法提取西南地区林芝、雅江、小金县产鲜松茸子实体样品中的挥发性物质,并采用气相色谱-质谱联用技术(gas chromatography-mass spectrometry,GC-MS)分析其化学成分。从3个样品的挥发性成分中依次确定出28、22、27个化合物,共计66种。结果显示林芝样与小金样的挥发性成分中有9个共同成分,两者主要成分依次为1-辛烯-3醇(28.43%)、亚油酸(33.86%);雅江样与前两者仅有2个共同成分,其主要成分为亚油酸甲酯(16.58%)和2-乙基己醛(16.54%)。其中林芝样和小金样中的1-辛烯-3-醇(蘑菇香)、雅江样中的2-乙基己醛(青草香)、小金样中的3-辛醇(蘑菇及黄油香)和苯乙醛(花蜜香)等C8醇及醛是导致3者香气差异的主要成分,可作为辅助西南地区不同产地松茸分类的化学鉴定指标。     

Effects of the volatile organic compounds produced by Enterococcus spp. strains isolated from maize grain silos on Fusarium verticillioides growth and fumonisin B1 production

Fusarium verticillioides is a phytopathogenic fungus that can contaminate maize grain silos and result in important losses in the post-harvest product. The objective of this work was to investigate the effects of volatile organic compounds produced by four lactic acid bacterial strains isolated from maize grain silos on F. verticillioides M3125 growth and fumonisin B₁ (FB₁) production. The bacterial isolates 55 and 49 were identified as Enterococcus faecium and M4A and M4G as Enterococcus casseliflavus. The fungal growth was inhibited by 33.33% by the volatiles released by the M4A strain and by approximately 10% by the volatiles emitted by the 55 and 49 strains. The volatiles produced by the M4A strain also significantly reduced (88.75%) FB₁ biosynthesis. The gas chromatography–mass spectrometer analysis identified 21 volatile organic compounds, with diacetyl, acetic acid and acetoin being the main volatiles emitted by the four bacterial strains. Acetoin was the volatile produced in the highest proportion by the four strains, with M4A generating the highest proportion of diacetyl (35.11%). Diacetyl and acetic acid completely inhibited fungal growth at concentrations of 0.3 and 1 mM, respectively, while acetoin promoted fungal growth. Only acetoin significantly reduced FB₁ production. These results showed that diacetyl was the main compound involved in fungal inhibition, while the effect on FB₁ production could have been due to the combination of the volatile organic compounds produced by the M4A strain. In conclusion, the volatiles emitted by the E. casseliflavus M4A strain could be a promising tool for the biocontrol of F. verticillioides in storage maize grain silos.     

Characterisation and identification of key cardboard-like off-odour compounds and possible origins in yoghurt using HS-SPME-GC–MS

Cardboard-like off-odour in yoghurt can negatively impact consumer acceptability. Herein, a method has been developed to analyse off-odorants in yoghurt using headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry. Of 56 volatile organic compounds identified, 8 were active compounds responsible for cardboard-like off-odour, including 2, 2-dimethyl-propanoic acid and 3-methyl-2-pentanone, which were newly identified in yoghurt. Hexanol and hexanal were found to be indicators of quality deterioration. The off-odour may be caused by packaging materials and temperature changes during logistic activities. Overall, identifying off-odorants can help producers to determine which part of the yoghurt-producing process can be changed to avoid contamination.     

微生物挥发性有机物检测及在食品安全监测中的应用

微生物挥发性有机物(MVOCs)是微生物生长代谢过程中产生的重要小分子化合物,是目前检测和防控食品受微生物污染的主要指标之一。本文全面综述了食品中MVOCs的分析检测技术及其在食品包装、贮藏、品质分析、腐败菌鉴定等监测食品安全方面的应用,对快速、准确、有效地评价食品微生物污染情况具有重要的现实意义。     

基于气相色谱-离子迁移谱法分析青霉侵染木耳菌丝的挥发性化合物

目的 基于气相色谱-离子迁移谱法(gas chromatography-ion mobility spectrometry, GC-IMS)研究青霉侵染木耳菌丝的挥发性化合物, 发掘潜在的特征标志物。方法 以分离自木耳菌包的桔青霉、歧皱青霉及黑木耳菌丝为研究对象, 采用气相色谱-离子迁移谱法(gas chromatography-ion mobility spectrometry, HS-GC-IMS)分析青霉侵染木耳菌丝不同时期挥发性化合物的种类及变化趋势, 并利用主成分分析(principal component analysis, PCA)比较不同侵染阶段挥发性化合物间的差异。结果 指纹图谱及PCA分析均可以比较明显地区分开青霉侵染木耳菌丝的不同阶段。挥发性化合物主要在桔青霉和歧皱青霉侵染木耳菌丝后的第4~8 d产生, 整体变化趋势基本一致, 共鉴定出41种化合物, 包括酯类、醇类、酮类、醛类及其他类。1-戊醇、乙酸己酯、2,3-戊二酮、2-丁酮、2,3丁二酮、1-丙醇、2-己醇、乙酸乙酯、丁酸乙酯、2-甲基丁酸等挥发性化合物可作为青霉侵染木耳菌丝的潜在标志物, 其中, 1-戊醇、乙酸己酯可作为青霉早期污染木耳菌丝的潜在标志物。3-羟基-2-丁酮可作为桔青霉侵染木耳菌丝后的潜在特征标志物。结论 本研究利用GC-IMS分析获得了两种青霉污染木耳菌丝的特征标志物, 为木耳栽培过程中青霉污染的早期预测提供了一定的理论基础。     

An investigation on molecular partition of aroma compounds in fruit matrix and brine medium of fermented table olives

Aroma is considered as a quality index of olive products. Fermented olives aroma compounds are present both in the fruit matrix and in brine medium. The partition of aroma compounds between fruit matrix and brine medium is deeply different for the two and depends on several factors such as carbon chain length and/or branching, number of polar groups, sodium salt concentration, temperature, etc. In this work, an investigation on volatile compounds quali-quantitative partition in fruit matrix and in brine medium of Greek-style Carolea and Nocellara del Belice table olives has been assessed. Volatile compounds have been extracted by using headspace method for olive fruit and by solvent extraction and distillation for brine medium. Twenty-three volatile compounds in fruit matrix and fifteen aroma molecules in brine medium have been identified by Gas Chromatography and GC/Mass Spectrometry. Results showed that most volatile organic compounds had a major affinity for the fruit matrix depending both on the chemical characteristics of the molecules (chain length and branching, polar or no polar groups, etc.) and on the “salting out” effect due to high NaCl concentration of the brine, which brought aroma compounds to hydrophobic phase of the olive fruit.

Industrial relevance

The study could be potentially helpful to develop analytical methods in order to estimate the quail-quantitative composition during the fermentation process. So that it would be possible to implement automatic analytical procedures in the currently used plants for the industrial production for table olives. Furthermore, this study allow us to identify off-flavours formed by anomalous fermentation process, in order to reveal them (both in the fruit and in the brine) in premature times (just in small traces), so to obtain the fermentation process recovery.     

百香果全果与果汁发酵酒滋味成分及香气成分对比

目的：提升百香果酒品质。方法：以百香果全果和果汁为原料酿制百香果酒,分别测定其有机酸、氨基酸和挥发性化合物含量,并结合电子舌试验结果评价百香果酒风味成分。结果：2种百香果发酵酒中主要有机酸为酒石酸、柠檬酸、乳酸和苹果酸,但全果酒的前3种有机酸含量均显著高于果汁酒中的（P<0.05）,全果酒和果汁酒中含量最多的有机酸分别为酒石酸（27.20 mg/mL）和柠檬酸（12.49 mg/mL）;除半胱氨酸未检出外,全果酒和果汁酒中16种游离氨基酸总含量分别为88.16,68.88 mg/100 g,且全果酒中4类呈味氨基酸含量高于果汁酒;电子舌测试发现,2种百香果发酵酒中咸味信号强度差异性最大,且全果酒中的鲜味、咸味最强,酸味、涩味和甜味最弱;HS-SPME-GC-MS共检出179种香气成分,全果酒中挥发性风味化合物种类比果汁酒多4种,但其萜烯类物质含量和种类分别比果汁酒的多1,3倍。结论：相比于果汁酒,新型百香果全果酒整体风味（鲜味、咸味、萜烯类物质等）较突出,提升了百香果资源的综合利用度。     

枸杞鲜果与干果发酵酒成分分析对比研究

测定了枸杞鲜果和干果发酵酒的氨基酸、蛋白质、有机酸、维生素、挥发性物质及高级脂肪酸等成分的含量,并对它们进行了对比分析,结果表明:枸杞鲜果发酵酒与干果发酵酒在氨基酸、VC、VE的含量上有较大的差异;利用鲜果发酵有利于VC的保持;利用干果发酵有利于VE的保持。     

山楂挥发性化合物的研究

用蒸馏-苹取法收集山楂中的挥发性化合物，经过气相色谱-质谱联用分析，在成熟山楂果实中共鉴定出32种沸点较低的挥发性化合物．占总挥发性成分的68．3％（以峰面积计）。其中主要的成分为顺-3-己烯醛、顺-3-乙酸己烯酯、a-萜品醇、糠醛、芳樟醇等。除芳樟醇外大多数挥发性成分的合量在山植果实成熟期间含量呈现增长趋势。在山植果实各成熟阶段，顺-3-己烯醛始终是含量最高的挥发性成分。顺-3-乙酸己酯在山楂果实成熟过程中含量增长速度最快，是山楂清香味的代表性化合物。山植果实中大多数挥发性化合物的形成机理可以用脂氧合酶降解途径解释。亚麻酸被认为是山楂香味主要的前体物质。     

HS-SPME-GC-MS分析玫瑰香葡萄中挥发性物质的萃取条件优化

原料选自宁夏贺兰山东麓玉泉营6年生玫瑰香,设置平衡时间分别为5 min、10 min、15 min,解吸时间分别为4 min、5 min、6 min,萃取温度分别为20 ℃、30 ℃和40 ℃,吸附时间分别为30 min、40 min和50 min,用顶空固相微萃取（HS-SPME）法对玫瑰香葡萄果实的挥发性物质进行萃取,以建立适宜于玫瑰香葡萄果实挥发性物质的气相色谱-质谱联用技术（GC-MS）分析方法。结果表明,萃取玫瑰香果实挥发性物质的最适萃取条件为平衡时间10 min,解吸时间5 min,萃取温度30 ℃,吸附时间40 min。在此优化萃取条件下,得到的挥发性物质的数量和响应强度较高,检测出玫瑰香果实的主要挥发性物质有芳樟醇、橙花醚、玫瑰醚、橙花醇、香叶醇、辛酸乙酯、柠檬醛、酞酸二甲酯、棕榈酸甲酯、正辛基醚等。     

正丁醇处理对‘粉红女士’苹果贮藏期间挥发性物质的影响

苹果的香气成分是构成苹果品质的重要因素,香气主要由挥发性物质描述,因此研究苹果挥发性物质具有重要意义。本试验为探究正丁醇处理对‘粉红女士’苹果挥发性物质的影响,以‘粉红女士’苹果为试材,分别用10和25 μL·L?1正丁醇溶液处理,采用有机溶剂萃取法提取挥发性物质,并利用气相色谱质谱联用仪（GC-MS）对其香气成分进行分析。结果表明:在各处理的整个贮藏期‘粉红女士’苹果果实中共检测出25种挥发性物质,包括酯类、醇类、醛类、酸类和萜烯类,以酯类和醛类物质为主;随着贮藏时间的延长,果实的挥发性物质种类减少,乙酸戊酯、丁酸丁酯、2-甲基-丙酸己酯、法尼醇和2-甲基丁酸未被检测到;25 μL·L?1处理组果实的乙酸戊酯、丁酸丁酯、2-甲基-丙酸己酯、法尼醇和2-甲基丁酸含量在贮藏第7 d和第14 d时明显高于对照组和10 μL·L?1处理组,此浓度正丁醇的添加能够促进贮藏前期果实挥发性酯类物质的产生。通过气味活性值分析发现有气味活性的化合物有19种,其中呈果香味的乙酸己酯是‘粉红女士’苹果主要的呈香物质。本研究表明,正丁醇的添加影响了‘粉红女士’苹果果实中酯类物质的产生,且25 μL·L?1处理组效果最显著,同时该研究可为‘粉红女士’苹果挥发性物质的研究提供理论基础。     

骏枣果醋发酵过程中营养品质变化及风味成分分析

以骏枣果酒为原料发酵果醋,对发酵过程中营养品质指标变化及发酵前后挥发性成分进行比较研究。结果表明,36～72 h期间为发酵产酸的主要时期,发酵过程中共检测到醋酸、草酸、柠檬酸、乳酸、琥珀酸、苹果酸6种有机酸,发酵后果醋中醋酸和琥珀酸含量分别为发酵前的15倍和3.7倍,乳酸和草酸含量则显著性降低,总酸味强度是果酒的6.17倍。发酵过程中总酚含量不断下降,维生素C含量先下降后趋于稳定,DPPH自由基清除率和总抗氧化能力显著升高。醋酸发酵前后共检测到挥发性成分65种,其中果醋检测到39种,相比果酒减少8种,果醋中酯类物质相对含量最高为37.42%,其中乙酸乙酯和乙酸异戊酯为主要的酯类物质,其次是酸类物质相对含量为30.69%。     

外源亚精胺对盐碱胁迫下番茄果实品质及挥发性成分的影响

本实验以"金棚朝冠"番茄为试材,研究外源喷施0.25 mmol/L亚精胺(spermidine,Spd)对75 mmol/L复合盐碱溶液(Na Cl、Na_2SO_4、NaHCO_3、Na_2CO_3浓度比为1∶9∶9∶1,pH 8.6)胁迫下番茄果实产量、品质的影响,利用顶空固相微萃取-气相色谱-质谱联用技术测定番茄果实挥发性物质成分和相对含量。实验分4个组:正常营养液浇灌+0 mmol/L Spd(CK组);正常营养液浇灌+0.25 mmol/L Spd(CS组);75 mmol/L复合盐碱溶液+0 mmol/L Spd(S组);75 mmol/L复合盐碱溶液+0.25 mmol/L Spd(SS组)。结果表明:盐碱胁迫条件下,喷施Spd可以显著提高番茄果实中VC、可溶性糖和番茄红素含量(P0.05),降低果实中有机酸和硝酸盐含量(P0.05),提高果实品质;同时显著提高了番茄的单株产量与单果质量(P0.05),保证番茄的高产。盐碱胁迫减少了果实挥发性物质数量和特征芳香物质的相对含量,喷施Spd缓解了胁迫对挥发性物质的相对含量和数量的影响。因此,盐碱胁迫条件下,喷施Spd可以提高番茄果实品质、增强果香、增加产量、降低不利因素对番茄果实品质和产量的影响。     

Mould and yeast flora in fresh berries, grapes and citrus fruits

Fresh fruits are prone to fungal contamination in the field, during harvest, transport, marketing, and with the consumer. It is important to identify fungal contaminants in fresh fruits because some moulds can grow and produce mycotoxins on these commodities while certain yeasts and moulds can cause infections or allergies. In this study, 251 fresh fruit samples including several varieties of grapes, strawberries, blueberries, raspberries, blackberries, and various citrus fruits were surface-disinfected, incubated at room temperature for up to 14 days without supplemental media, and subsequently examined for mould and yeast growth. The level of contamination (percent of contaminated items/sample) varied depending on the type of fruit. All raspberry and blackberry samples were contaminated at levels ranging from 33% to 100%, whereas 95% of the blueberry samples supported mould growth at levels between 10% and 100% of the tested berries, and 97% of strawberry samples showed fungal growth on 33-100% of tested berries. The most common moulds isolated from these commodities were Botrytis cinerea, Rhizopus (in strawberries), Alternaria, Penicillium, Cladosporium and Fusarium followed by yeasts, Trichoderma and Aureobasidium. Thirty-five percent of the grape samples tested were contaminated and supported fungal growth; the levels of contamination ranged from 9% to 80%. The most common fungi spoiling grapes were Alternaria, B. cinerea and Cladosporium. Eighty-three percent of the citrus fruit samples showed fungal growth at levels ranging from 25% to 100% of tested fruits. The most common fungi in citrus fruits were Alternaria, Cladosporium, Penicillium, Fusarium and yeasts. Less common were Trichoderma, Geotrichum and Rhizopus.     

Volatile compounds of Panax ginseng C.A. Meyer cultured with different cultivation methods

The volatile compounds of Panax ginseng C.A. Meyer analyzed to interpret whether cultivation methods affect volatile compounds. The volatile compounds in Panax ginseng C.A. Meyer cultured with 3 different cultivation methods such as good agricultural practice, organic cultivation method, and general cultivation method were isolated by solid-phase microextraction fiber (polydimethylsiloxane 65 μm) and identified by gas chromatography mass spectrometry. Then, the scattering patterns of volatile compounds compared by principal component analysis. As the results, the 14 volatile compounds were identified from 30 ginseng samples and consisted mainly of sesquiterpene hydrocarbons. The differences among the different cultivation methods of the samples were obvious from the PC1 and PC2 scatter point plot. As the conclusion, the cultivation methods can affect to produce the volatile component of ginseng root. The organic and good agriculture practice cultivation can increase the ginseng characteristic volatile compounds.