Determination of volatile compounds of precooked prawn (Penaeus vannamei) and cultured gilthead sea bream (Sparus aurata) stored in ice as possible spoilage markers using solid phase microextraction and gas chromatography/mass spectrometry

BACKGROUND: Solid phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) have been reported as useful techniques for analysing volatile compounds to monitor fish freshness. In this study, SPME/GC/MS was applied to cultured gilthead sea bream and precooked prawn stored in ice for 6 days in order to find possible markers of spoilage. Total volatile basic nitrogen (TVB‐N) was also determined as a common index of spoilage. RESULTS: The TVB‐N value at the end of the storage period for cultured gilthead sea bream (302.40 ± 8.50 mg kg^?1) was within the range of acceptability for edible fish (300–400 mg kg^?1) but could be considered at the beginning of spoilage. For precooked prawn the TVB‐N value at day 6 (863.04 ± 7.84 mg kg^?1) was not acceptable for human consumption. SPME/GC/MS identified 30 compounds in cultured gilthead sea bream and 49 compounds in precooked prawn. In particular, 3‐methyl‐1‐butanol, 2‐methylbutanal, 3‐methylbutanal and 3‐hydroxy‐2‐butanone increased during refrigerated storage both in the two species investigated here and in other species reported elsewhere and could be considered as markers of spoilage. CONCLUSION: This study confirmed that SPME/GC/MS can be considered an efficient method suitable for analysing the volatile compounds of both raw fish and fishery products in order to monitor loss of freshness. Copyright © 2008 Society of Chemical Industry     

Differentiation of fresh and frozen/thawed fish, European sea bass (Dicentrarchus labrax), gilthead seabream (Sparus aurata), cod (Gadus morhua) and salmon (Salmo salar), using volatile compounds by SPME/GC/MS

BACKGROUND: A simple method based on solid phase microextraction/gas chromatography/mass spectrometry (SPME/GC/MS) was applied for studying the volatile profiles of whole fish samples of European sea bass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) and fillets of cod (Gadus morhua) and salmon (Salmo salar) during frozen storage in order to be able to differentiate a fresh product from one that has been frozen. Analysis of volatile compounds was performed on these two product types, fresh and after freezing/thawing following storage at ? 20 °C for 30 and 90 days. RESULTS: More than a hundred volatile compounds were found by SPME/GC/MS. Statistical processing by principal component analysis and ascending hierarchical classification was used to classify the samples into categories and verify the possibility of separating fresh samples from those that had been frozen and thawed. The compounds to be used as differentiators were identified. Four compounds were common to all species: dimethyl sulfide, 3‐methylbutanal, ethyl acetate and 2‐methylbutanal. Not only were they found in larger quantities after thawing but they also increased with the duration of storage at ? 20 °C. CONCLUSION: These four compounds can therefore be considered as potential markers of differentiation between a fresh product and one that has been frozen. Copyright © 2012 Society of Chemical Industry     

Determination of volatile compounds to characterize fish spoilage using headspace/mass spectrometry and solid‐phase microextraction/gas chromatography/mass spectrometry

Changes in volatile compounds were monitored in whiting (Merlangius merlangus), cod (Gadus morhua) and mackerel (Scomber scombrus) and related to spoilage. Data are presented from headspace/mass spectrometric (HS/MS) analysis and solid‐phase microextraction/gas chromatographic/mass spectrometric (SPME/GC/MS) analysis at two time points (day 0 and day 10) during storage at 4 °C. HS/MS revealed 24 ions that could be used as markers of spoilage. SPME/GC/MS identified 86 compounds, 20 of which could perhaps be used to characterize freshness: principally alcohols, ketones, aldehydes and C₂–C₁₁ esters. Compounds common to the three species studied appear to be generated by microbial degradation. Copyright © 2005 Society of Chemical Industry     

Change of volatile compounds in fresh fish meat during ice storage

Abstract: The change of volatile compounds in fresh fish meat during 3‐ to 4‐d ice storage was investigated for several fishes using an electronic nose system and a gas chromatography‐mass spectrometer (GC/MS) with headspace solid‐phase micro‐extraction (SPME). Principal component analyses for samples using the electronic nose system revealed that the increase of some volatile compounds during storage was rapid in sardine (Sardinops melanostictus), jack mackerel (Trachurus japonicus), and chub mackerel (Scomber japonicus); moderate in yellowtail (Seriola quinqueradiata), skipjack (Katsuwonus pelamis), and young oriental bluefin tuna (Thunnus thynnus). In contrast to these fishes, the change was little in “white meat” fishes such as red seabream (Chrysophrys major), Japanese seabass (Lateolabrax japonicus), flatfish (Paralichthys olivaceus), puffer (Lagocephalus wheeleri), and bartail flathead (Platycephalus indicus). SPME‐GC/MS analysis showed that some aldehydes and alcohols such as 1‐heptanol, (E)‐2‐octenal, (E)‐2‐hexenal, 1‐pentanol, (E,E)‐2,4‐heptadienal,2,4‐hexadienal, 1‐hexanol, 4‐heptenal, and so forth increased rapidly in jack mackerel and chub mackerel, slowly in skipjack, and a little in red seabream and puffer during the storage. The increase of these compounds was considered to have an effect on the change of electronic nose response. Hexanal was a dominant compound increased from the beginning of the storage in jack mackerel. The increase of volatile compounds was little in red seabream and puffer. The increase of these aldehydes and alcohols was thought to be an appropriate marker for monitoring the freshness of “fresh” fish except for white meat fish. Practical Application: The results of this study are ready to apply for preventing fishy off‐flavor of fisheries products. Lipid oxidative derivatives other than trimethylamine contributed to fresh fish flavor; therefore, to prevent lipid oxidation seemed important.     

Characterization of volatile compounds in Fen‐Daqu – a traditional Chinese liquor fermentation starter

Fen‐Daqu is a saccharifying agent and fermentation starter for the production of Chinese liquor Fen (alcoholic spirit) and Fen traditional vinegar. The volatile compounds produced at seven incubation steps were analysed by HS‐SPME‐GC‐MS. A total of 83 major volatile compounds were identified, including 23 esters, 8 acids, 24 alcohols, 18 ketones and aldehydes, 6 pyrazines and 4 acetals. Data obtained by HS‐SPME‐GC‐MS were subjected to principal component analysis. The trajectory plots of volatile compounds in Fen‐Daqu samples obtained during successive steps of incubation were revealed. The major compounds that contributed to discrimination were hexanal, (E)‐2‐octenal, (Z)‐2‐octen‐1‐ol, nonanoic acid, 1‐octanol, 2‐decen‐1‐ol, hexyl acetate, (E)‐2‐octen‐1‐ol, acetic acid, ethyl acetate, phenylethyl alcohol, ethyl alcohol, octanoic acid, 1‐octanol, 3‐methyl‐2‐buten‐1‐ol and pyrazines. Copyright © 2012 The Institute of Brewing & Distilling     

Volatile organic compounds associated with milk spoilage by psychrotrophic bacteria

The volatile organic compounds of milk contaminated with psychrotrophic bacteria were studied by HS‐SPME and GC/MS. Pseudomonas fluorescens PS14, Pseudomonas fragi PS55, Pseudomonas mosselii PS39, Pseudomonas rhodesiae PS62 and Serratia marcescens S92 were inoculated in sterilised milk (2.5% fat) stored at either 5 °C or 10 °C. A total of 47 volatile organic compounds (VOCs) belonging to seven chemical groups were identified in the spoiled milk. Volatile organic compound patterns peculiar to the inoculate bacterial strains were highlighted. 3‐Methylbutan‐1‐ol, 2 methylpropan‐1‐ol, 3‐hydroxybutan‐2‐one, butan‐2,3‐dione, butanoic and hexanoic acids were revealed as potential chemical spoilage indexes of milk spoilage due to the activity of the five psychrotrophic strains studied.     

Oxidatively Derived Volatile Compounds in Microencapsulated Fish Oil Monitored by Solid-phase Microextraction (SPME)

The stability of microencapsulated fish oil was studied during storage at 4 °C for up to 20 wk. Different coating mixtures consisting of gelatin or caseinate in blends with carbohydrates (sucrose, lactose, maltodextrin) were investigated. Oxidative stability of the microencapsulated fish oil was monitored by analysis of volatile compounds using gas chromatography olfactometry (GC‐O) or GC flame ionization (GC‐FID) (SPME‐HS‐GC/O or GC/ FID and HS‐GC/MS), Oxipres test, thiobarbituric acid‐reactive substances (TBARS), and sensory analysis. Coating mixture of caseinate and lactose showed slightly better stability than the sucrose and maltodextrin caseinate mixtures. Combination of fish gelatin and maltodextrin did not show as good oxidative stability as the coating blend of caseinate, lactose, and lecithin. Hexanal, 2‐nonenal and 2,4‐decadienals were selected as quality indicators to monitor the lipid oxidation during storage of the samples. SPME‐GC‐O analysis of these indicators showed that they were representative for the oxidation occurring in the microencapsulated fish oil. SPME‐GC‐FID analysis was sensitive enough to detect oxidative changes during storage. Oxidative stability test, TBARS results, and sensory analysis were in agreement with the SPME, indicating that SPME (polydimethylsiloxane/divinylbenzene [PDMS/ DVB] fiber) can be a useful tool for rapid analysis of lipid oxidation in microencapsulated fish oil.     

SDE and SPME Analysis of Flavor Compounds in Jin Xuan Oolong Tea

Simultaneous distillation‐extraction (SDE) and solid phase micro extraction (SPME) are procedures used for the isolation of flavor compounds in foods. The purpose of this study was to optimize SDE conditions (solvent and time) and to compare SDE with SPME for the isolation of flavor compounds in Jin Xuan oolong tea using GC‐MS and GC‐O. The concentration of volatile compounds isolated with diethyl ether was higher (P < 0.05) than for dichloromethane and concentration was higher at 40 min (P < 0.05) than 20 or 60 min extractions. For SDE, 128 volatiles were identified using GC‐MS and 45 aroma active compounds using GC‐O. Trans‐nerolidol was the most abundant compound in oolong tea. The number of volatiles identified using GC‐MS was lower in SPME than SDE. For SPME, 59 volatiles and 41 aroma active compounds were identified. The composition of the volatiles isolated by the 2 methods differed considerably but provided complementary information.     

Analysis and characterization of aroma‐active compounds of Schizandra chinensis (omija) leaves

Volatile components from leaves of Schizandra chinensis (omija), a native plant of Korea, were extracted by simultaneous distillation–extraction (SDE) and analyzed by gas chromatography–mass spectrometry (GC‐MS) using two types of capillary column with different polarities (DB‐5MS and DB‐Wax). The GC‐MS analysis of volatile compounds obtained by SDE revealed that germacrene D is the most abundant compound (22.6%) in omija leaves, followed by β‐elemene (17.4%), (E)‐2‐hexenal (8.7%), and (E)‐β‐ocimene (7.2%). Aroma‐active compounds were determined by gas chromatography–olfactometry (GC‐O) using the aroma‐extract‐dilution analysis method. (E,Z)‐2,6‐Nonadienal (cucumber) was the most intense aroma‐active compound due to its higher flavor‐dilution factor (243–729) than any other compound. (Z)‐3‐Hexenal (green/apple), (E)‐2‐hexenal (green/fruity), and (E)‐β‐ocimene (wither green/grass) were also identified as important aroma‐active compounds by GC‐O. In addition, the volatile compounds were extracted by solid‐phase microextraction (SPME), and the quantitative analysis of the SPME samples gave slightly different results, depending on the type of SPME fiber, compared with those from SDE, However, the aroma‐active compounds identified in SPME were similar to those in SDE. Copyright © 2004 Society of Chemical Industry     

Aroma Characterization of Virgin Olive Oil from Two Turkish Olive Varieties by SPME/GC/MS

Virgin olive oil samples of Ayvalik and Memecik olive varieties from the Aegean region of Turkey were evaluated for their acidity, peroxide, and color values, and the volatile compounds were investigated by using solid phasemicro extraction/gas chromatography/mass spectroscopy (SPME/GC/MS). The acidity of all the samples were found to be between 0.35–1.0% oleic acid and peroxide values of the oil samples ranged between 14–52 meq/O₂ kg of oil. The Y, R, and B values of the samples were between 70–73.60, 1.30–4.70, and 0–3.60, respectively. The SPME/GC/MS results have shown that hexanal (5.66–15.48%), 3 hexen 1 ol (3.12–12.1%), cis 3 hexenol (6.15–13.49%), and 9 octadecenoic acid (5.99-16.01%) were observed as the characteristic volatiles for Ayvalik variety, while trans 2 hexanal (8.65–38.09%) and 3 hexen 1 ol acetate (0.97–7.43%) were observed as the characteristic volatiles for Memecik variety.     

Screening and distinction of coffee brews based on headspace solid phase microextraction/gas chromatography/principal component analysis

The volatile profiles of espresso and plunger (cafetière) coffees prepared from (1) an 80:20 (w/w) blend of natural roasted Robusta and Arabica (Robusta Natural blend), (2) a 40:40:20 (w/w/w) blend of Robusta Natural blend, Robusta torrefacto roast (850 g kg^?1 Robusta, 150 g kg^?1 sugar) and (3) natural roasted pure Arabica were established by headspace solid phase microextraction (SPME) after selection of the fibre coating (polyacrylate or polydimethylsiloxane) and the temperature and time of extraction. For the analysis of furans and indoles the polyacrylate coating proved to be more suitable; however, for the overall characterisation of the volatile composition of espresso and plunger coffees the polydimethylsiloxane coating was chosen. SPME/gas chromatography (GC)/mass spectrometry (MS) analyses allowed the identification of 37 compounds: four aldehydes, two ketones, 11 furans, 10 pyrazines, two pyridines, three phenolic compounds, two indoles, one lactone, one ester and one benzothiazine. The volatile composition was related more to the botanical variety (Arabica or Robusta) than to the method of preparation of the brew (espresso or plunger). Furthermore, use of the variability provided solely by the GC peak areas and respective retention times, combined with principal component analysis (PCA), yielded the information necessary for discrimination. The combined technique of headspace SPME/GC/PCA, as an alternative to conventional techniques based on GC/MS, is proposed as a lower‐cost, fast and reliable technique for the screening and distinction of coffee brews. Copyright © 2003 Society of Chemical Industry     

Solid phase microextraction (SPME) applied to honey quality control

The assessment of the botanical origin of unifloral honeys is an important application in food control. The current official methods mainly use pollen analysis. The aim of this paper is to present an SPME analytical approach to the study of honey volatiles. Honey samples (40) obtained from hive sites in different regions of Italy were analysed. The samples had six different botanical origins: citrus (five), chestnut (10), eucalyptus (eight), lime tree (11), thyme (two) and dandelion (four). Melissopalynological analysis was also performed. Identification of volatile compounds was carried out by SPME/GC/MS analysis, and quantitative evaluation was done by SPME/GC/FID analysis for compounds with well‐resolved peaks. Using the SPME method, all samples with the same botanical origin gave remarkably similar GC profiles. Some volatile compounds were found only in specific floral source honey samples and thus could be interesting for use as markers. Copyright © 2003 Society of Chemical Industry     

Study of the volatile profile characteristics of longan during storage by a combination sampling method coupled with GC/MS

BACKGROUND: Longan (Dimocarpus longan Lour.) is a kind of subtropical fruit, but it has a very short shelf life under normal ambient conditions. In this work, a combination sampling method, including headspace solid phase micro‐extraction (HSSPME), simultaneous distillation extraction (SDE) and steam distillation (SD), was used to study the volatile profile characteristics of longan at the fresh and deteriorated storage phases followed by gas chromatography–mass spectrometry (GC‐MS) detection. The study would provide a method for investigating the volatile profile characteristics of longan during storage and some helpful clues for quality discrimination. RESULTS: In total, 28 and 22 volatile compounds of fresh and deteriorated longan were identified. Alkenes and esters were the main volatile components of longan. β‐ocimene accumulated, whereas allo‐ocimene and 3,4‐dimethyl‐2,4,6‐octatriene decreased during storage. Different volatile profile characteristics at the fresh and deteriorated storage phases obtained by HSSPME were specified by principal component analysis (PCA). Typical volatile compounds were distilled by a common model strategy. CONCLUSION: The volatile profiles of longan during storage were studied using a combination of sampling methods followed by GC‐MS detection. Five typical volatiles contributing significantly to the difference in volatile profile characteristics of longan at the fresh and deteriorated storage phases were distilled using a common model strategy. These compounds are potential bio‐markers for longan degradation. Tentative results suggest that combining HSSPME with conventional volatile isolation methods would provided more representative data on changes in the volatile compounds of longan during storage and some helpful clues for quality discrimination. Copyright © 2008 Society of Chemical Industry     

Evaluation of the chemical,microbiological and volatile aroma characteristics of Ispir Kaymak,a traditional Turkish dairy product

The gross chemical composition, microbiological quality and volatile aroma composition of Ispir Kaymak, a Turkish creamy dairy product, were investigated in 10 samples. The chemical composition of the samples varied widely: dry matter content ranged from 70.8% to 91.3% and fat varied between 43.0% and 63.0%; probably due to the lack of standardised production in practice. The microbiological counts were found to be (as mean values): 4.02, 3.06, 0.33, <2 log cfu/g for aerobic plate count, yeast and mould, coliform and Staphylococcus aureus, respectively. The sample quality showed that the production and storage conditions should be controlled and the hygienic quality of this product should be improved. A total of 73 volatile compounds, including esters, acids, ketones, aldehydes, alcohols, terpenes and miscellaneous compounds, were identified in the volatile fraction of the samples by gas chromatography–mass spectrometry (GC–MS) using a solid‐phase microextraction technique (SPME/GC–MS). Esters were the main volatiles in Ispir Kaymak, and ketones, alcohols and terpenes were found at high levels; however, the levels of acids were low in all samples.     

Study of the volatile composition of tomato during storage by a combination sampling method coupled with gas chromatography/mass spectrometry

BACKGROUND: The volatile compositions of common tomato (Lycopersicon esculentum var. commune) and cherry tomato (Lycopersicon esculentum var. cerasiforme) during storage were studied by a combination sampling method, including headspace solid phase microextraction (HSSPME), simultaneous distillation extraction (SDE) and steam distillation (SD), coupled with gas chromatography/mass spectrometry (GC/MS) detection. RESULTS: Twenty‐one and 14 volatile compounds of fresh and stale common tomatoes and 27 and 17 volatile compounds of fresh and stale cherry tomatoes were identified with various degrees of certainty. The main identified volatile compounds of common and cherry tomatoes were C6 alcohols and aldehydes. During storage, saturated hexanal increased gradually whereas unsaturated (E)‐2‐hexenal decreased. Different volatile compositional characteristics at the fresh and stale storage phases obtained by HSSPME were specified by principal component analysis (PCA). Different metabolic pathways and enzyme catalyses resulted in the various volatile compositional characteristics during tomato storage. Five typical volatile compounds contributing greatly to the difference in volatile compositional characteristics of common and cherry tomatoes at the fresh and stale storage phases were distilled by a common model strategy. These compounds are potential biomarkers for tomato degradation, but further study is needed. CONCLUSION: The preliminary results suggest that the combination of HSSPME and conventional sampling methods would yield more representative information on changes in tomato volatile composition during storage. Copyright © 2007 Society of Chemical Industry     

Relationship between changes in the total concentration of acetic acid bacteria and major volatile compounds during the acetic acid fermentation of white wine

BACKGROUND: In the scope of the wine vinegar production, this paper provides comprehensive information about the evolution of some volatile compounds during the biological acetification cycle. These data were compared with the acidity, cell concentration and ethanol concentration. Such information may allow a better understanding of the complex biological processes involved. RESULTS: The volatile compounds 2‐phenylethanol, diethyl succinate (diethyl butanedioate), meso‐2,3‐butanediol (meso‐butane‐2,3‐diol), levo‐2,3‐butanediol (levo‐butane‐2,3‐diol), methanol and ethyl acetate exhibited no significant changes between the starting wine and produced vinegar, whereas the rest [acetoin (3‐hydroxybutan‐2‐one) excepted] ethyl lactate (ethyl 2‐hydroxypropanoate), isoamyl alcohols (3‐methylbutan‐1‐ol and 2‐methylbutan‐1‐ol), isobutanol (2‐methylpropan‐1‐ol), 1‐propanol (propan‐1‐ol), and acetaldehyde were consumed in substantial amounts during the process. Additionally, their specific evolution patterns alongside bacterial cell concentrations, acidity and ethanol concentration are shown. CONCLUSION: Concentrations of acetic acid bacteria at the end of the acetification cycle were found to vary because of cell lysis, a result of the high acidity and low ethanol concentration of the medium. Variations were similar to those in some volatile compounds, which suggests their involvement in the metabolism of acetic bacteria. The results testify to the usefulness of this pioneering study and suggest that there should be interest in similar, more detailed studies for a better knowledge of the presence of certain volatile compounds and metabolic activity in cells effecting the acetification of wine. Copyright © 2010 Society of Chemical Industry     

Effect of starter cultures on the quality of Suan yu,a Chinese traditional fermented freshwater fish

The generation of volatile compounds of four starter cultures composed of isolated microorganisms from traditional Suan yu was investigated. The cultures included two pure starters (PS1: Lactobacillus plantarum 120 and PS2: Pediococcus pentosaceus 220) and two mixed starters (MS1: L. plantarum 120, Staphylococcus xylosus 135 and Saccharomyces cerevisiae 31 at 1:1:1; MS2: P. pentosaceus 220, S. xylosus 135 and S. cerevisiae 31 at 1:1:1). Naturally fermented Suan yu was used as control. The volatile compounds were collected from the headspace of the samples by Solid‐phase microextraction and analysed by gas chromatography–mass spectrometry. The type and total content of volatile compounds in the mixed‐starter‐fermented fish were higher than those of the pure‐starter‐fermented samples and control. A total of seventy nine and eighty volatile compounds were detected in Suan yu fermented with MS1 and MS2, respectively, with ethanol as the predominant compound and hexanal, ethyl acetate, 3‐methylbutanol, 3‐hydroxy‐2‐butanone, hexanoic acid ethyl ester and 2,3‐butanedione as the other compounds. Furthermore, the sensorial acceptance of the different products with mixed starter cultures seemed to improve the quality of Suan yu products.     

Analysis of characteristic aroma of fungal fermented Fuzhuan brick‐tea by gas chromatography/mass spectrophotometry

Fuzhuan brick‐tea is a popular fermented Chinese dark tea because of its typical fungal aroma. Fungal growth during the production process is the key step in achieving the unique colour, aroma and taste of Fuzhuan brick‐tea. To further understand the generation of the characteristic aroma, changes in the main volatile compounds of Fuzhuan brick‐tea during the fungal growth stage were studied by gas chromatography/mass spectrophotometry. The results showed that the content of volatile compounds, especially aldehyde compounds with stale aroma such as (E)‐2‐pentenal, (E)‐2‐hexenal, 1‐penten‐3‐ol, (E, E)‐2,4‐heptadienal and (E, Z)‐2,4‐heptadienal, increased significantly in fermented tea samples. The concentration of terpene alcohols with flower aroma also increased notably during the fermentation process. The compounds with stale and flower aromas in combination with some volatile components of the raw material contributed to the characteristic ‘fungal/flower’ aroma of Fuzhuan brick‐tea. Microbial metabolism during the fermentation process probably played the key role in the generation of characteristic aromatic compounds of Fuzhuan brick‐tea. Copyright © 2007 Society of Chemical Industry     

Analysis of volatile compounds in L. edodes blanched by hot water and microwave

The comprehensive flavour characterisation and volatile compounds of raw L. edodes, hot water blanching (HB) sample and microwave blanching (MB) sample were comparatively analysed by electronic nose technology and headspace solid‐phase micro‐extraction combined with gas chromatography‐mass spectrometry (HS‐SPME‐GC‐MS). Results indicated that volatile components in L. edodes markedly changed after HB and MB. Volatile compounds of raw L. edodes consisted mainly ketones, sulphide and alcohols, and 3‐octanone, as well as 1‐octen‐3‐one, were the major compounds. The content of ketones and sulphides in blanched samples markedly decreased, while the relative content of aldehydes, hydrocarbons and esters increased, which became the major volatile compounds of treatment samples. In addition, the percentage contents of esters, alcohols and sulphides in MB samples were significantly (P < 0.05) higher than that in HB samples, especially 1‐octen‐3‐ol, which contributes more to mushroom flavour. Therefore, MB is a better pretreatment method of L. edodes processing and cooking according to the results of experiment.