Effect of hot-air drying on flavour compounds of bell peppers (Capsicum annuum)

The influence of hot-air drying on the composition of both volatile and non-volatile flavour compounds of different Dutch bell pepper cultivars was investigated. Contents of glucose, fructose, ascorbic, citric, and oxalic acid decreased significantly after drying, while the levels of sucrose, malic, fumaric, and cis-aconitic acid increased. Glucose, fructose and ascorbic acid probably participate in Maillard reactions during heating. Different effects of drying could be distinguished on the composition of volatile compounds. The majority of these compounds evaporated during drying. Some compounds were partly retained in the dried bell peppers, whereas others disappeared completely. Gas chromatography-sniffing port analysis revealed that compounds with mainly “fresh” odour notes like lettuce/grassy/green bell pepper ((Z-2-3-hexenal), fruity/almond ((E)-2-hexenal), fruity (octanal), lettuce/green bell pepper ((Z)-3-hexenol), and grassy/green bell pepper ((Z)-2-hexenal) decreased or disappeared after drying. Another group of compounds increased or were formed during drying, like 4-octen-3-one, (E)-2-heptenal, (E)-2-octenal, (E,Z)- and (E,E)-2,4-heptadienal, decanal, and (E)-2-nonenal; most are known as autoxidation products of unsatu-rated fatty acids. The increased levels of 2-methylpropionic and 2- and 3-methylbutyric acid, 2-metlhylpropanal, and 2- and 3-methylbutanal seemed to be due to Strecker degradation. Gas chromatography-sniffing port analysis showed that the latter three compounds had distinct cacao, sweaty, and spicy odour characteristics.     

Characterization of odor-active compounds in three varieties of ciruela (Spondias purpurea L.) fruit

The aroma-active compounds present in tree ripened fruits of ciruela (Spondias purpurea L.) cultivars Chi abal, Campech abal, and Ek abal were isolated by means of simultaneous distillation solvent extraction and solid-phase microextraction and analyzed by gas chromatography-mass spectrometry. Application of odor activity values (OAV) afforded 22 compounds in higher amounts than their threshold concentrations (OAVs >1). Results of the identification experiments in combination with the OAVs suggested that methyl 3-methylbutanoate, ethyl butanoate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl hexanoate, hexyl acetate, with fruity odor notes; (E)-2-hexenal, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, 1-hexanol, and (Z)-3-hexenyl acetate, with grassy odor notes, and limonene (citrus-like) were the potentially important common odorants in all ciruela cultivars. Clear differences in the OAVs of some odorants between each of the cultivars suggested that they contributed to the unique sensory profiles of the individual cultivars.     

Analysis of flavor volatile compounds by dynamic headspace in traditional and hybrid cultivars of Spanish tomatoes

A system specifically designed for the non-destructive analysis of volatile organic compounds in fresh tomatoes, based on a dynamic headspace technique, has been set up to quantify the volatile aroma constituents of tomato fruits. This system will reduce the high variability associated to sample selection in post-harvest studies. Volatile compounds with a major contribution to aroma have been quantitatively determined in two traditional tomato cultivars and one commercial F1 hybrid. One of the traditional cultivars, “De la Pera,” got the highest values of odor and aroma in sensory tests performed using a trained panel of 10 assessors. The same cultivar showed significantly higher contents of all eight volatile compounds studied (hexanal, trans-2-hexenal, cis-3-hexenol, 1-hexanol, 1-nitro-3-methylbutane, 6-methyl-5-hepten-2-one, 2-isobutylthiazole, and β-ionone). Significant differences among traditional and hybrid tomato cultivars can be detected for volatile compounds, thus allowing the use of volatile determination as a possible tool in tomato breeding programs.     

Comparison of Volatile Release in Tomatillo and Different Varieties of Tomato during Chewing

ABSTRACT: The release of volatiles from tomatillos (Physalis ixocarpa Brot.) and tomatoes in the mouthspace and nosespace was measured in real-time using selected ion flow tube mass spectrometry (SIFT-MS). (Z)-3-Hexenal, (E)-2-hexenal, hexanal, and 1-penten-3-one increased, while isobutyl alcohol, nonanal, and methylbutanal showed no significant change in the first 30 s of chewing. Cherry tomato released more (E)-2-hexenal, (Z)-3-hexenal, and 1-penten-3-one than tomatillo, Roma tomato, and vine-ripened tomato during chewing. The proportion of the average concentration of volatiles in the mouthspace after swallowing to before swallowing (MSas/MSbs) varied from 2.8% to 73.9% between different volatiles and varieties. Methylbutanal, hexanal, and nonanal were retained at a higher percentage in the mouth after swallowing than (Z)-3-hexenal, (E)-2-hexenal, 1-penten-3-one, and isobutyl alcohol. The proportion of the average volatile concentration in the mouthspace, to the headspace in a glass container (MS/HS) of 1-penten-3-one, hexanal, methylbutanal, and nonanal, and the proportion of nosespace to headspace (NS/HS) for 1-penten-3-one, hexanal, (Z)-3-hexenal, and nonanal was significantly higher in tomatillo than in tomatoes. There was no difference between tomatoes of different varieties in NS/HS ratio. Practical Application: The real-time volatile release from tomatillos and tomatoes was measured and compared. The information obtained on the dynamic generation of volatile compounds provides a better understanding of volatile release in the headspace of tomatillo and tomatoes. The compounds and their volatile release patterns were similar for the tomatillo and tomatoes. The green aldehydes released during chewing were not significantly higher than most tomato varieties, except for Roma tomatoes. Cherry tomato released relatively more volatiles during chewing, whereas Roma tomatoes were generally poor in mouthspace volatiles. The lingering of volatiles in the mouth after swallowing was different for different volatiles and varieties, which may appear as a sensory difference detected by consumers.     

Olfactory and quantitative analysis of volatiles in elderberry (Sambucus nigra L) juice processed from seven cultivars

Aroma compounds emitted from elderberry juices processed from seven cultivars were collected by the dynamic headspace technique and analysed by GC–FID and GC–MS. Forty aroma compounds were identified and quantified, including nine compounds which had not previously been detected in elderberry juice. Significant differences were found among cultivars in the concentration levels of 30 compounds. The sensory characteristics of the individual aroma compounds in elderberry juice were determined by a GC‐sniffing technique, and the compounds were grouped according to their odour. The characteristic elderberry odour is due to dihydroedulan and β‐damascenone, of which the former occurs in relatively high concentrations in the headspace of elderberry juice. The fruity group consisted of aliphatic alcohols and aldehydes and aromatic esters, of which 1‐pentanal, 2‐methyl‐1‐propanol, 2‐ and 3‐methyl‐1‐butanol, 1‐octanal, 1‐octanol and methyl and ethyl benzoate contributed with fruity notes. In the flowery group, 1‐nonanal, nerol oxide and (Z)‐ and (E)‐rose oxide contributed with characteristic elder flower odour, whereas other flowery notes were associated with hotrienol, linalool and α‐terpineol. Fresh and grassy odours were correlated with 1‐hexanal, (E)‐2‐hexen‐1‐al, (Z)‐3‐hexen‐1‐ol, (E)‐2‐hexen‐1‐ol and (E)‐2‐octen‐1‐al of the grassy group, whereas 1‐octen‐3‐ol and 1‐octen‐3‐one of the agrestic group contributed significantly with the characteristic aroma of mushrooms. © 2000 Society of Chemical Industry     

Comparison of the key aroma compounds in hand-squeezed and unpasteurised,commercial NFC juices prepared from Brazilian Pera Rio oranges

Application of a comparative aroma extract dilution analysis on a hand-squeezed (juice A) and an industrially squeezed, unpasteurised orange juice (juice B), revealed qualitatively almost the same set of odour-active compounds. However, while in juice A, vanillin, ethyl butanoate, wine lactone, (Z)-3-hexenal, (S)-ethyl 2-methylbutanoate and (S)-linalool were detected with the highest flavour dilution (FD) factors, in juice B prepared by means of an FMC extractor, several compounds, like (R)-limonene, (R)-α-pinene and octanal showed higher FD factors, in addition to ethyl butanoate, wine lactone and (S)-ethyl 2-methylbutanoate. Quantification of seventeen odorants in both juices by means of stable isotope dilution assays followed by a calculation of odour activity values (OAV; ratio of concentration to odour threshold) revealed a clear change in the ranking order: while (S)-ethyl 2-methylbutanoate, (R)-limonene, (Z)-3-hexenal and linalool were first in rank among the odorants of juice A, in juice B, (R)-limonene and (S)-linalool followed by (S)-ethyl 2-methylbutanoate showed the highest OAVs. Sensory experiments revealed that the much higher concentrations of the seven peel oil constituents, and the lack in (Z)-3-hexenal, are the reason for the aroma differences observed for both juices. Further experiments indicated that lowering the pressure during commercial juicing, and also the avoidance of a freezing/thawing process could be helpful in getting closer to the aroma of hand-squeezed orange juice, because peel oil constituents are lowered and, in particular, the latter procedure leads to a complete degradation of (Z)-3-hexenal.     

Volatile and non-volatile chemical composition of the white guava fruit (Psidium guajava) at different stages of maturity

The effect of the maturation stages on the chemical composition and volatile compounds of the white Guava (Psidium guajava) Cv. Cortibel was investigated during three different stages. The stages were characterized by evolution of color, pH, titratable acidity, sugars, soluble solids, vitamin C and volatile components. The fruits were stored at 24 °C and air humidity of 74% for 13 days. The volatile extracts were obtained using headspace technique and analyzed using gas chromatograph/mass spectrometry (GC/MS) system. The titratable acidity and sugars decreased. The pH level and amount of vitamin C increased throughout progress of maturation. The behavior of volatile compounds of fruits in the three stages of maturation was: in immature fruits and those in their intermediate stage of maturation, were predominantly the aldehydes such as (E)-2-hexenal and (Z)-3-hexenal. In mature fruits, esters like Z-3-hexenyl acetate and E-3-hexenyl acetate and sesquiterpenes caryophyllene, α-humulene and β-bisabollene are present.     

Identification and origin of the character‐impact compounds of raw oyster Crassostrea gigas

The French consume large amounts of raw oysters. The study of the aroma of oyster Crassostrea gigas is of economic interest because it is a good method of checking the sensory quality. Aromas were extracted by vacuum steam distillation at 20 °C using whole oyster flesh. This extract presented similar sensory characteristics to raw oyster. The odour‐active compounds were characterised by gas chromatography coupled with olfactometry using a panel of 10 judges trained in seafood aroma recognition. Fifty‐nine volatile compounds were identified in oyster aroma extract. Among these, 25 were responsible for the overall odour of raw oyster. Four compounds identified in oysters were characterised by fresh and marine odour: 3‐(E)‐hexen‐1‐ol, decanal, 2‐undecanone and 3,6‐(E,Z)‐nonadien‐1‐ol. Some compounds were identified for the first time in oysters: 4‐(Z)‐heptenal (white boiled fish odour), which comes from n‐3 polyunsaturated fatty acid oxidation, and 3‐octanol (moss and sulphury odour), 2‐nonanol (cucumber odour) and octanoic acid, which arise from n‐6 polyunsaturated fatty acid oxidation. © 2002 Society of Chemical Industry     

Aroma-active compounds of butter: a review

This review article shows that more than 230 volatile compounds have been identified in butter, however, only a small number of them can be considered as key odorants of butter aroma. Gas chromatography olfactometry was used to determine the character impact odorants of different kinds of butter. Sweet cream butter is characterised by lactones with fruity and creamy notes and by sulphur compounds, having corn-like and garlic odours. The key odour compounds of sour cream butter are diacetyl (buttery-like), butanoic acid (cheesy) and δ-decalactone (peach), mainly due to lactic acid bacteria fermentation. The aroma of butter oil is characterised by aldehydes, such as (E)- and (Z)-2-nonenal and (E,E)-2,4-decadienal, conferring green and oily notes. Olfactometric studies of heated butter showed the formation of new aroma compounds during heating, such as 3-methylbutanoic acid (cheesy), methional (potato-like) and 2,5-dimethyl-4-hydroxy-3-(2H)-furanone (caramel-like). High temperature treatment of butter can also induce off-flavour development. Off-odours in butter originate from autooxidative and as well as from lipolytic reactions, microbial contamination and animal feeding. The views expressed in this publication are the sole responsibility of the authors and do not necessarily reflect the views of the European Commission. Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use, which might be made of the information contained herein.     

Storage studies of tomato and bell pepper using eco‐friendly films

Tomato (Lycopersicon esculentum) and bell pepper (Capsicum annuum), packaged in cartons (approximately 0.35 kg per box) covered with either eco‐friendly chitosan film or synthetic petroleum‐based low‐density polyethylene (LDPE) film, were stored at room temperature (27 ± 1 °C) and 65 ± 3% relative humidity (RH). Fruits were withdrawn periodically and changes in physico‐chemical, instrumental and sensory characteristics were analysed. During storage, oxygen levels showed only marginal changes, while CO₂ levels showed a gradual increase, especially so in LDPE film‐covered cartons. The fresh weight loss, colour, firmness, formation of defective spots and shrivelling showed greater changes for unpackaged fruits as well as for those in LDPE film‐covered cartons, in comparison with fruits stored in chitosan film‐covered cartons, which retained many of the desirable attributes. Principle component analysis of data from sensory or instrumental sensory analyses indicated segregation of samples stored under different conditions with respect to both desirable and undesirable attributes. The fruits showed greater deterioration, including the loss of characteristic bell pepper odour, when packaged in cartons covered with LDPE films, while those packaged in chitosan film retained more of the desirable quality attributes for a longer period. Copyright © 2006 Society of Chemical Industry     

Degradation of cucumber flavor aldehydes in juice

The effect of 1,10-phenanthroline (PTL) on stability of aldehydes, especially, (E,Z)-2,6-nonadienal (NDEA) and (E)-2-nonenal (NEA), produced during tissue disruption of cucumber fruit (Cucumis sativus) was studied. Volatiles in headspace of cucumber juice samples treated with 0 or 20 μg ml^{− 1} PTL were collected by SPME and analyzed by GC–MS. Within 4 h at 30 °C more than 90% of the initial NDEA, NEA, (Z)-6-nonenal, (E)-2-hexenal, hexanal, (E)-2-pentenal, propanal and ethanal disappeared in juice without PTL. During the loss of these aldehydes, several alcohols were detected. In contrast, levels of NDEA, NEA and (Z)-6-nonenal in PTL treated juice gradually declined during holding for 24 h at 30 °C; the amounts of other aldehydes remained relatively constant; and no alcohols were detected except for ethanol which was initially present. Therefore, inhibiting reduction of aldehydes to alcohols greatly hindered degradation of cucumber flavor aldehydes.     

脂质对凡纳滨对虾热风干制品香气特性的影响

为研究脂质对凡纳滨对虾热风干制品香气特性的影响,通过有机试剂去除虾体中的甘油三酯或磷脂,采用气相色谱-质谱联用技术和感官评价分析脂质对虾干制品香气特性的影响,以气味活性值(odor activity value,OAV)为指标,筛选香气活性化合物,同时采用偏最小二乘回归法(partial least squares regression,PLSR)分析挥发性化合物与感官属性之间的相关性。结果表明:去除甘油三酯对虾干制品整体香气影响较小,烤香味、肉香味和腥味的感官评分稍有减弱,而去除磷脂对主要香气特征有很大影响,烤香味、肉香味、腥味、焦糖香和甜香味的感官评分均大幅度降低;虾干制品中鉴定出16种香气活性化合物,吡嗪类、胺类、杂环类、醛类是其主要成分,其中3-乙基-2,5-二甲基吡嗪、2,5-二甲基吡嗪、三甲胺、3-(甲硫基)丙醛是贡献最大的4种物质;去除甘油三酯和磷脂后,吡嗪类、胺类、杂环类、醛类的OAV值显著下降,而去除磷脂后下降幅度更大,且在去磷脂虾干制品中2-戊基呋喃和3-(甲硫基)丙醛未检出;PLSR结果表明,18种香气活性化合物与感官属性具有较好的相关性。综上所述,脂质对虾干制品整体香气有较大影响,而磷脂对香气特性的作用远大于甘油三酯。该研究为虾类特征香气的形成机制研究提供了理论参考。     

不同煎炸阶段薯条和煎炸油中关键风味成分分析（网络首发、推荐阅读）

风味是薯条受欢迎程度的决定性感官特征。煎炸油一旦加热,油脂的变化会直接影响食物的风味。在高油酸菜籽油(RO)煎炸过程中,煎炸薯条(FF)的风味发展表现出三个明显的阶段,包括诱导阶段(总极性化合物(TPC)的含量为3.0%~8.0%)、最佳阶段(TPC的含量为8.0%~20%)和降解阶段(TPC的含量为22%以上)。为了区分各阶段的关键香气化合物,选择了极性化合物为3.0%(FF1)、10.5%(FF2)和27%(FF3)的高油酸菜籽油制备的薯条及其相关油(RO1、RO2、RO3)进行感官分析。结果表明,FF1中,(E,E)-2,4-癸二醛(油炸气味)含量较低,这可能是FF1样品感官评分较低的原因。与FF1和FF2相比,FF3具有较高的己酸(汗臭味)、庚酸、壬酸、苯乙醛和反式-4,5-环氧-(E)-2-癸烯醛(金属气味),导致FF3的风味恶化。此外,FF3中2,5-二甲基吡嗪和2-乙基-6-甲基-吡嗪的减少导致了较低的烘焙风味,可能使得感官评分下降。同样,RO3中(E)-2-十一烯醛、己酸、庚酸和壬酸含量较高,其酸败评分增加,从而降低感官评分。当TPC含量超过22%时,油的过氧化作用会引起酸败味,因此煎炸后期应加以控制,通过研究煎炸过程中关键风味物质的变化,对开发具有最佳风味的油炸产品有借鉴意义。     

SPME-GC-MS detection of volatile compounds in apricot varieties

Aroma compounds of the eight Malatya apricot cultivars, six cultivars grown in the same breeding conditions from different locations and one hybrid cultivar were determined using SPME-GC-MS technique. In general, total concentration (sum of identified and unidentified peaks) of aroma compounds in Malatya apricot cultivars were lower than those others. Total concentration of aroma compounds were found to be in the range of 514 and 6232 μg/kg fresh weight. The main volatiles of apricot cultivars were aldehydes, alcohols, acetates, esters, terpenes and acids. Among these compounds; ethanol, hexanal, hexyl acetate, (Z)-3-hexenyl acetate, (E)-2-hexenyl acetate, 1-hexanol, (Z)-3-hexenol and (E)-2-hexen-1-ol, were present in all cultivars studied at certain levels.     

Olfactometric characterization of aroma active compounds in fermented fish paste in comparison with fish sauce,fermented soy paste and sauce products

Aroma active compounds in commercial fermented fish meat paste product (fish miso), fermented soy paste (soy miso), fish sauce and soy sauces were characterized by using a dynamic headspace method for volatile isolation and GC olfactometry for odor perception. A total of 123 volatile compounds consisting mainly of aldehydes, alcohols, esters, ketones, furans, sulfur and nitrogen-containing compounds, aromatics and acids were consistently identified. A major 16 odor-active compounds were distinguished to contribute as key aroma compounds for the miso and sauce products. Olfactometric and sensory findings clearly differentiated miso products with caramelic, fruity aroma notes, whereas fish sauce products were characterized by ammoniacal, fishy, nutty and cheesy odor note. Soy sauce products, however, were dominated by nutty and cheese aroma. Use of koji for fish miso production was found effective to enhance sweet aroma to the product with a reduction of nutty, meaty and rancid nuance. Principal component analysis employed for statistical interpretations clearly elucidated the relationship among different types of fermented products.