Abstract In this paper a method for the cholesterol oxidation products (oxysterols) determination... more Abstract In this paper a method for the cholesterol oxidation products (oxysterols) determination in milk powder and infant formulas has been presented. In the sample preparation step lipids transesterification has been performed. The recoveries of ...
Broccoli is characterized by its specific flavor, which is the reason it is not tolerated by some... more Broccoli is characterized by its specific flavor, which is the reason it is not tolerated by some consumers. The role of aroma in flavor is crucial; however, the characteristics of aroma‐active components in broccoli are still unclear. Solvent‐assisted flavor evaporation (SAFE) with the aid of solid‐phase microextraction (SPME) and fractionation using solid phase extraction (SPE), followed by different chromatography‐mass spectrometry approaches (GC‐MS, GC‐MS/MS, GC×GC‐ToFMS) were used to identify the compounds of interest. A total of 33 aroma‐active compounds were detected with the use of gas chromatography‐olfactometry (GC‐O) in raw, and 9 in cooked broccoli florets; in majority sulfur compounds—thiols, sulfides, and isothiocyanates prevailed. Methanethiol and 1‐pentanethiol were the key odorants characterized by the highest FD (1024) in raw broccoli, followed by dimethyl sulfide, 2,3‐butanedione, dimethyl trisulfide, dimethyl tetrasulfide, 2‐methyl methanethiosulphonate, 4‐methylpentyl isothiocyanate, hexyl isothiocyanate (all with an FD of 256). In cooked broccoli, the number and especially the intensity of detected compounds were much lower. The highest FD values (FD=4) were noted for dimethyl trisulfide and 1,4‐octadien‐3‐one. To our knowledge, this is the first detailed identification of odorants in raw and cooked broccoli.
Baijiu is a traditional Chinese spirit with an extraordinarily rich pattern of volatile compounds... more Baijiu is a traditional Chinese spirit with an extraordinarily rich pattern of volatile compounds resulting from the microflora involved in fermentation, as well as the complexity of technological process. Comprehensive two-dimensional gas chromatography in the conventional and reversed column setups (non-polar - polar and polar - non-polar columns) was tested for its ability to differentiate Baijiu samples in terms of their aroma and origin (region). A total of 65 Baijiu samples were used for the study and volatile compounds were extracted by SPME with a subsequent analysis by GC×GC-TOFMS. Orthogonality of both setups was compared, so was the number of compounds identified using each setup. Repeatability of compound groups for the conventional and reversed column setups was compared; moreover, multiblock orthogonal component analysis (MOCA) was used to visualize data sets. OPLS-DA was used for Baijiu classification. Both column setups provided excellent discrimination of the Light, Soy sauce, Feng and Herbal aromas. A better classification result for the Strong and Jian aromas was recorded for the conventional column setup. Within the Strong aroma using OPLS-DA both column setups provided perfect abilities to discriminate Baijiu from the Sichuan, Heilongjiang and Jiangsu regions. Two validation methods were applied in the classification models - all the predictive abilities evaluated by the internal validation were further confirmed by the external validation.
Journal of Agricultural and Food Chemistry, Feb 1, 2017
Application of gas chromatography olfactometry (GC-O) carried out on the volatile fraction isolat... more Application of gas chromatography olfactometry (GC-O) carried out on the volatile fraction isolated by solvent assisted flavor evaporation (SAFE) and solid phase microextraction (SPME) from Lazur-mold-ripened cheese revealed 17 odor-active compounds. The highest flavor dilution factor (FD) has been obtained for methanethiol (2048) with burnt odor note and for 2(3)-methyl butanoic acid (2048) with cheesy, pungent odor. Further quantitation of 15 most aroma-active compounds allowed for calculation of their odor activity values (OAV). The highest OAV was obtained for methanethiol (500), 3(2)-methyl butanoic acid (321), 3-(methylthio)-propanal (210), 2,3-butanedione (65), dimethyl trisulfide (22), butanoic acid (20), 1-octen-3-ol (18), (Z)-4-heptenal (14), dimethyl disulfide (14), dimethyl sulfide (13), phenylacetaldehyde (6), 2-ethyl-3,5-dimethyl pyrazine (5) and acetic acid (4). Aroma recombination experiment showed slight difference in the perception of cheesy/sweaty and moldy/musty notes. To verify influence of methyl ketones on aroma profile of moldripened cheese, recombinant has been additionally supplemented with the addition of 2pentanone, 2-heptanone and 2-nonanone in concentrations determined in Lazur cheese. The aroma profile remained unchanged, which would suggest that methyl ketones, in this particular cheese do not play a significant role in the formation of aroma.
Solid-phase microextraction-mass spectrometry (SPME-MS) and fast gas chromatography based electro... more Solid-phase microextraction-mass spectrometry (SPME-MS) and fast gas chromatography based electronic nose (GC-E-Nose) were used and compared for their suitability to distinguish Baijiu of various aroma types and geographical origin. Baijiu is a traditional Chinese distilled spirit produced with complex consortia of microorganisms, which results in very complex aroma compounds profiles. A total of 65 Baijiu samples representing 6 aromas were investigated. Strong aroma types from 3 regions were examined for their origin. Data acquired on two analytical systems were processed using uniform statistical approach. Data were pre-processed for multiclassification (OPLS-DA) models as well as for binary classification (PLS-DA) ones. Aroma and regional classification performed using OPLS-DA indicated that the approach based on SPME-MS had better fitness and prediction ability compared with GC-E-Nose. The total correct classification rate for SPME-MS was 94.44% for aroma and 100% for region, whereas for GC-E-Nose these values were 91.53% and 93.94% respectively.
Solid phase microextraction (SPME) is widely used in food flavor compounds analysis in majority f... more Solid phase microextraction (SPME) is widely used in food flavor compounds analysis in majority for profiling volatile compounds. Based on such profiles conclusions are often drawn concerning the percentage composition of volatile compounds in particular food, spices or raw materials. This paper focuses on the usefulness of SPME for the profiling of volatile compounds from spices using black pepper as an example. SPME profiles obtained in different analytical conditions were compared to the profile of pepper volatiles obtained using hydrodistillation in Clevenger apparatus. The profiles of both monoterpenes and sesquiterpenes of black pepper were highly dependent on sample weight (0.1 and 1g samples were tested), and extraction time (durations from 2 to 120min were tested), regardless of the SPME fiber used (PDMS and CAR/PDMS coatings were used). The characteristic phenomenon for extraction from dry ground pepper was the decrease of monoterpenes % share in volatiles with increasing extraction times, whereas at the same time the % contents of sesquiterpenes increased. Addition of water to ground pepper substantially changed extraction kinetics and mutual proportions of mono to sesquiterpenes compared to dry samples by minimizing changes in mono- to sesquiterpenes ratio in different extraction times. Obtained results indicate that SPME can be a fast extraction method for volatiles of black pepper. Short extraction times (2-10min) in conjunction with the fast GC analysis (2.1min) proposed here may offer fast alternative to hydrodistillation allowing black pepper terpenes characterization.
Broccoli is characterized by its specific flavor, which is the reason it is not tolerated by some... more Broccoli is characterized by its specific flavor, which is the reason it is not tolerated by some consumers. The role of aroma in flavor is crucial; however, the characteristics of aroma‐active components in broccoli are still unclear. Solvent‐assisted flavor evaporation (SAFE) with the aid of solid‐phase microextraction (SPME) and fractionation using solid phase extraction (SPE), followed by different chromatography‐mass spectrometry approaches (GC‐MS, GC‐MS/MS, GC×GC‐ToFMS) were used to identify the compounds of interest. A total of 33 aroma‐active compounds were detected with the use of gas chromatography‐olfactometry (GC‐O) in raw, and 9 in cooked broccoli florets; in majority sulfur compounds—thiols, sulfides, and isothiocyanates prevailed. Methanethiol and 1‐pentanethiol were the key odorants characterized by the highest FD (1024) in raw broccoli, followed by dimethyl sulfide, 2,3‐butanedione, dimethyl trisulfide, dimethyl tetrasulfide, 2‐methyl methanethiosulphonate, 4‐methyl...
Baijiu is a Chinese spirit which is produced by a complex process involving solid state fermentat... more Baijiu is a Chinese spirit which is produced by a complex process involving solid state fermentation with various raw materials and a consortium of microorganisms resulting in an abundance of fermentation by products. A method was developed for quantification of 62 compounds in Baijiu spirits using simultaneous direct injection to two columns (CPWax-57CB and DB-624). Dual column analysis substantially increased the reliability of identification using a flame ionisation detector. The method had high linearity-for all but one compound-indicated by the coefficient of determination (R 2) of ≥ 0.999 (in a range of 0.3-260 mg/L) and reproducibility (for the majority of compounds at a concentration of ca. 1 mg/L, < 5% for the DB-624 columns and < 8% for the CPWax-57CB column). The limit of detection was < 1 mg/L for all compounds. The method was used to analyse volatile compounds in 38 samples of Baijiu, from different regions and flavour types. The main group of compounds in the volatile fraction were esters and higher alcohols. Based on Orthogonal Partial Least Squares Discriminant Analysis it was not possible to separate the samples in terms of region, but it was possible to distinguish between strong and soy sauce types of Baijiu from the other samples.
Journal of the American Oil Chemists' Society, 2018
Volatile compounds of argan oils obtained from raw and roasted kernels and subjected to accelerat... more Volatile compounds of argan oils obtained from raw and roasted kernels and subjected to accelerated storage test at 60 °C were profiled by means of headspace solid‐phase microextraction with gas chromatography coupled with high‐resolution time‐of‐flight mass spectrometry (HS‐SPME‐GC‐HRToFMS), followed by statistical multivariate analysis (MVA). Main volatile markers differentiating oils during storage were identified as 2‐methylbutanal, acetic acid, pentanal, hexanal, 2,5‐dimethylpyrazine, methyl pyrazine, 2,3‐butanediol, and 1‐methyl‐1H‐pyrrole. Principal component analysis (PCA) results show that MVA is suitable for differentiating between raw and roasted argan oils of various degrees of oxidation. Key odorants in both oils were determined by gas chromatography‐olfactometry (GC‐O) analysis, indicating butanal as the most prominent odorant for raw argan oil (flavor dilution [FD] = 8), whereas 3‐isopropyl‐2‐methoxypyrazine and 2‐ethyl‐3,5‐dimethylpyrazine with FD values of 1024 were...
Two varieties of rapeseed (one high oleic - containing 76% of oleic acid, and the other - contain... more Two varieties of rapeseed (one high oleic - containing 76% of oleic acid, and the other - containing 62% of oleic acid) were used to produce virgin (pressed) oil. The rapeseeds were roasted at different temperature/time combinations (at 140-180°C, and for 5-15min); subsequently, oil was pressed from the roasted seeds. The roasting improved the flavour and contributed to a substantial increase in the amount of a potent antioxidant-canolol. The changes in volatile compounds related to roasting conditions were monitored using comprehensive gas chromatography-mass spectrometry (GC×GC-ToFMS), and the key odorants for the non-roasted and roasted seeds oils were determined by gas chromatography-olfactometry (GC-O). The most important compounds determining the flavour of oils obtained from the roasted seeds were dimethyl sulphide, dimethyltrisulfide, 2,3-diethyl-5-methylpyrazine, 2,3-butenedione, octanal, 3-isopropyl-2-methoxypyrazine and phenylacetaldehyde. For the oils obtained from the n...
Polish Journal of Food and Nutrition Sciences, 2007
This paper investigates the effectiveness of electronic nose with subsequent principal component ... more This paper investigates the effectiveness of electronic nose with subsequent principal component analysis (PCA) treatment of data for differentiation of food samples of varied odour quality caused by lipid oxidation. Samples were evaluated for off-flavours with an electronic nose and a sensory analysis and for Totox value. Volatile compounds of fresh samples and samples subjected to storage test at 60°C were isolated with a static headspace technique. The results suggest that the electronic nose could help to supplement the sensory analysis. Models based on partial least-squares analysis were able to predict the oxidized flavour attribute of samples, with correlation coefficients ranging from 0.66 to 0.99. Based on elaborated methods and data treatment with PCA it was possible to distinguish between different food samples and monitor the formation of off-flavours associated with lipid oxidation.
An overview of lipids oxidation in foods, its main aspects and implications for the customer has ... more An overview of lipids oxidation in foods, its main aspects and implications for the customer has been outlined in a concise form. Three different mechanisms of fatty acid oxidation yielding different products are described: autoxidation, photo-oxidation and lipooxygenase action. Oxidation of sterols and fat-soluble vitamins (named A, D, E and K), all isoprenoic compounds, as a part of unsaponificable fraction of lipid are included to review. It is indicated that relatively little information exists on oxyphytosterols. The contents of these compounds in food products are presented. The crucial significance for the sensory aspect of food quality is ascribed to volatiles from lipid oxidation products. Some volatiles with low odour threshold are characterized. Nutritional problem of lipid oxidation products and products obtained by interactions with other food components is discussed. Use of antioxidants as important factors in reducing the risk of chronic diseases and its economical aspects is discussed. The need for search of natural antioxidant, commonly perceived as safe is stressed. Last part of review covers the methods for the assessment of lipid oxidation. Classic methods for the determination of lipid stability, for the measurement of lipid oxidation are described. Also chromatographic analyses of volatile compounds generated in the lipid oxidation process included static, dynamic head space and SPME are discussed. The novel approaches to the analysis of these volatiles such as chemometrical methods and electronic noses are also presented.
The effect of wheat kernel medium supplementation with octanoic acid on the formation of PR toxin... more The effect of wheat kernel medium supplementation with octanoic acid on the formation of PR toxin and some volatiles by Penicillium roqueforti was investigated. Octanoic acid was added to the medium once, prior to inoculation (4.55 mg g-1), or periodically (total 27.3 mg g-1) during the 10 day course of incubation. No octanoic acid was added to the reference sample. Levels of 2-heptanone, 2-heptanol and aristolochene, a volatile intermediate in PR toxin biosynthesis, were monitored using a solid phase microextraction (SPME) technique. The contents of PR toxin and ergosterol were determined after incubation. Aristolochene was observed in the reference sample, and 10.4 mg kg-1 of PR toxin was detected after 10 days. In cultures periodically supplemented with octanoic acid, no aristolochene or PR toxin were observed. However, in samples supplemented with octanoic acid only prior to incubation, the aristolochene level was 25% that in the reference sample, and PR toxin content was 3.4 mg kg-1. These data suggest that a high level of octanoic acid in the medium prevents PR toxin formation by P. roqueforti.
Abstract In this paper a method for the cholesterol oxidation products (oxysterols) determination... more Abstract In this paper a method for the cholesterol oxidation products (oxysterols) determination in milk powder and infant formulas has been presented. In the sample preparation step lipids transesterification has been performed. The recoveries of ...
Broccoli is characterized by its specific flavor, which is the reason it is not tolerated by some... more Broccoli is characterized by its specific flavor, which is the reason it is not tolerated by some consumers. The role of aroma in flavor is crucial; however, the characteristics of aroma‐active components in broccoli are still unclear. Solvent‐assisted flavor evaporation (SAFE) with the aid of solid‐phase microextraction (SPME) and fractionation using solid phase extraction (SPE), followed by different chromatography‐mass spectrometry approaches (GC‐MS, GC‐MS/MS, GC×GC‐ToFMS) were used to identify the compounds of interest. A total of 33 aroma‐active compounds were detected with the use of gas chromatography‐olfactometry (GC‐O) in raw, and 9 in cooked broccoli florets; in majority sulfur compounds—thiols, sulfides, and isothiocyanates prevailed. Methanethiol and 1‐pentanethiol were the key odorants characterized by the highest FD (1024) in raw broccoli, followed by dimethyl sulfide, 2,3‐butanedione, dimethyl trisulfide, dimethyl tetrasulfide, 2‐methyl methanethiosulphonate, 4‐methylpentyl isothiocyanate, hexyl isothiocyanate (all with an FD of 256). In cooked broccoli, the number and especially the intensity of detected compounds were much lower. The highest FD values (FD=4) were noted for dimethyl trisulfide and 1,4‐octadien‐3‐one. To our knowledge, this is the first detailed identification of odorants in raw and cooked broccoli.
Baijiu is a traditional Chinese spirit with an extraordinarily rich pattern of volatile compounds... more Baijiu is a traditional Chinese spirit with an extraordinarily rich pattern of volatile compounds resulting from the microflora involved in fermentation, as well as the complexity of technological process. Comprehensive two-dimensional gas chromatography in the conventional and reversed column setups (non-polar - polar and polar - non-polar columns) was tested for its ability to differentiate Baijiu samples in terms of their aroma and origin (region). A total of 65 Baijiu samples were used for the study and volatile compounds were extracted by SPME with a subsequent analysis by GC×GC-TOFMS. Orthogonality of both setups was compared, so was the number of compounds identified using each setup. Repeatability of compound groups for the conventional and reversed column setups was compared; moreover, multiblock orthogonal component analysis (MOCA) was used to visualize data sets. OPLS-DA was used for Baijiu classification. Both column setups provided excellent discrimination of the Light, Soy sauce, Feng and Herbal aromas. A better classification result for the Strong and Jian aromas was recorded for the conventional column setup. Within the Strong aroma using OPLS-DA both column setups provided perfect abilities to discriminate Baijiu from the Sichuan, Heilongjiang and Jiangsu regions. Two validation methods were applied in the classification models - all the predictive abilities evaluated by the internal validation were further confirmed by the external validation.
Journal of Agricultural and Food Chemistry, Feb 1, 2017
Application of gas chromatography olfactometry (GC-O) carried out on the volatile fraction isolat... more Application of gas chromatography olfactometry (GC-O) carried out on the volatile fraction isolated by solvent assisted flavor evaporation (SAFE) and solid phase microextraction (SPME) from Lazur-mold-ripened cheese revealed 17 odor-active compounds. The highest flavor dilution factor (FD) has been obtained for methanethiol (2048) with burnt odor note and for 2(3)-methyl butanoic acid (2048) with cheesy, pungent odor. Further quantitation of 15 most aroma-active compounds allowed for calculation of their odor activity values (OAV). The highest OAV was obtained for methanethiol (500), 3(2)-methyl butanoic acid (321), 3-(methylthio)-propanal (210), 2,3-butanedione (65), dimethyl trisulfide (22), butanoic acid (20), 1-octen-3-ol (18), (Z)-4-heptenal (14), dimethyl disulfide (14), dimethyl sulfide (13), phenylacetaldehyde (6), 2-ethyl-3,5-dimethyl pyrazine (5) and acetic acid (4). Aroma recombination experiment showed slight difference in the perception of cheesy/sweaty and moldy/musty notes. To verify influence of methyl ketones on aroma profile of moldripened cheese, recombinant has been additionally supplemented with the addition of 2pentanone, 2-heptanone and 2-nonanone in concentrations determined in Lazur cheese. The aroma profile remained unchanged, which would suggest that methyl ketones, in this particular cheese do not play a significant role in the formation of aroma.
Solid-phase microextraction-mass spectrometry (SPME-MS) and fast gas chromatography based electro... more Solid-phase microextraction-mass spectrometry (SPME-MS) and fast gas chromatography based electronic nose (GC-E-Nose) were used and compared for their suitability to distinguish Baijiu of various aroma types and geographical origin. Baijiu is a traditional Chinese distilled spirit produced with complex consortia of microorganisms, which results in very complex aroma compounds profiles. A total of 65 Baijiu samples representing 6 aromas were investigated. Strong aroma types from 3 regions were examined for their origin. Data acquired on two analytical systems were processed using uniform statistical approach. Data were pre-processed for multiclassification (OPLS-DA) models as well as for binary classification (PLS-DA) ones. Aroma and regional classification performed using OPLS-DA indicated that the approach based on SPME-MS had better fitness and prediction ability compared with GC-E-Nose. The total correct classification rate for SPME-MS was 94.44% for aroma and 100% for region, whereas for GC-E-Nose these values were 91.53% and 93.94% respectively.
Solid phase microextraction (SPME) is widely used in food flavor compounds analysis in majority f... more Solid phase microextraction (SPME) is widely used in food flavor compounds analysis in majority for profiling volatile compounds. Based on such profiles conclusions are often drawn concerning the percentage composition of volatile compounds in particular food, spices or raw materials. This paper focuses on the usefulness of SPME for the profiling of volatile compounds from spices using black pepper as an example. SPME profiles obtained in different analytical conditions were compared to the profile of pepper volatiles obtained using hydrodistillation in Clevenger apparatus. The profiles of both monoterpenes and sesquiterpenes of black pepper were highly dependent on sample weight (0.1 and 1g samples were tested), and extraction time (durations from 2 to 120min were tested), regardless of the SPME fiber used (PDMS and CAR/PDMS coatings were used). The characteristic phenomenon for extraction from dry ground pepper was the decrease of monoterpenes % share in volatiles with increasing extraction times, whereas at the same time the % contents of sesquiterpenes increased. Addition of water to ground pepper substantially changed extraction kinetics and mutual proportions of mono to sesquiterpenes compared to dry samples by minimizing changes in mono- to sesquiterpenes ratio in different extraction times. Obtained results indicate that SPME can be a fast extraction method for volatiles of black pepper. Short extraction times (2-10min) in conjunction with the fast GC analysis (2.1min) proposed here may offer fast alternative to hydrodistillation allowing black pepper terpenes characterization.
Broccoli is characterized by its specific flavor, which is the reason it is not tolerated by some... more Broccoli is characterized by its specific flavor, which is the reason it is not tolerated by some consumers. The role of aroma in flavor is crucial; however, the characteristics of aroma‐active components in broccoli are still unclear. Solvent‐assisted flavor evaporation (SAFE) with the aid of solid‐phase microextraction (SPME) and fractionation using solid phase extraction (SPE), followed by different chromatography‐mass spectrometry approaches (GC‐MS, GC‐MS/MS, GC×GC‐ToFMS) were used to identify the compounds of interest. A total of 33 aroma‐active compounds were detected with the use of gas chromatography‐olfactometry (GC‐O) in raw, and 9 in cooked broccoli florets; in majority sulfur compounds—thiols, sulfides, and isothiocyanates prevailed. Methanethiol and 1‐pentanethiol were the key odorants characterized by the highest FD (1024) in raw broccoli, followed by dimethyl sulfide, 2,3‐butanedione, dimethyl trisulfide, dimethyl tetrasulfide, 2‐methyl methanethiosulphonate, 4‐methyl...
Baijiu is a Chinese spirit which is produced by a complex process involving solid state fermentat... more Baijiu is a Chinese spirit which is produced by a complex process involving solid state fermentation with various raw materials and a consortium of microorganisms resulting in an abundance of fermentation by products. A method was developed for quantification of 62 compounds in Baijiu spirits using simultaneous direct injection to two columns (CPWax-57CB and DB-624). Dual column analysis substantially increased the reliability of identification using a flame ionisation detector. The method had high linearity-for all but one compound-indicated by the coefficient of determination (R 2) of ≥ 0.999 (in a range of 0.3-260 mg/L) and reproducibility (for the majority of compounds at a concentration of ca. 1 mg/L, < 5% for the DB-624 columns and < 8% for the CPWax-57CB column). The limit of detection was < 1 mg/L for all compounds. The method was used to analyse volatile compounds in 38 samples of Baijiu, from different regions and flavour types. The main group of compounds in the volatile fraction were esters and higher alcohols. Based on Orthogonal Partial Least Squares Discriminant Analysis it was not possible to separate the samples in terms of region, but it was possible to distinguish between strong and soy sauce types of Baijiu from the other samples.
Journal of the American Oil Chemists' Society, 2018
Volatile compounds of argan oils obtained from raw and roasted kernels and subjected to accelerat... more Volatile compounds of argan oils obtained from raw and roasted kernels and subjected to accelerated storage test at 60 °C were profiled by means of headspace solid‐phase microextraction with gas chromatography coupled with high‐resolution time‐of‐flight mass spectrometry (HS‐SPME‐GC‐HRToFMS), followed by statistical multivariate analysis (MVA). Main volatile markers differentiating oils during storage were identified as 2‐methylbutanal, acetic acid, pentanal, hexanal, 2,5‐dimethylpyrazine, methyl pyrazine, 2,3‐butanediol, and 1‐methyl‐1H‐pyrrole. Principal component analysis (PCA) results show that MVA is suitable for differentiating between raw and roasted argan oils of various degrees of oxidation. Key odorants in both oils were determined by gas chromatography‐olfactometry (GC‐O) analysis, indicating butanal as the most prominent odorant for raw argan oil (flavor dilution [FD] = 8), whereas 3‐isopropyl‐2‐methoxypyrazine and 2‐ethyl‐3,5‐dimethylpyrazine with FD values of 1024 were...
Two varieties of rapeseed (one high oleic - containing 76% of oleic acid, and the other - contain... more Two varieties of rapeseed (one high oleic - containing 76% of oleic acid, and the other - containing 62% of oleic acid) were used to produce virgin (pressed) oil. The rapeseeds were roasted at different temperature/time combinations (at 140-180°C, and for 5-15min); subsequently, oil was pressed from the roasted seeds. The roasting improved the flavour and contributed to a substantial increase in the amount of a potent antioxidant-canolol. The changes in volatile compounds related to roasting conditions were monitored using comprehensive gas chromatography-mass spectrometry (GC×GC-ToFMS), and the key odorants for the non-roasted and roasted seeds oils were determined by gas chromatography-olfactometry (GC-O). The most important compounds determining the flavour of oils obtained from the roasted seeds were dimethyl sulphide, dimethyltrisulfide, 2,3-diethyl-5-methylpyrazine, 2,3-butenedione, octanal, 3-isopropyl-2-methoxypyrazine and phenylacetaldehyde. For the oils obtained from the n...
Polish Journal of Food and Nutrition Sciences, 2007
This paper investigates the effectiveness of electronic nose with subsequent principal component ... more This paper investigates the effectiveness of electronic nose with subsequent principal component analysis (PCA) treatment of data for differentiation of food samples of varied odour quality caused by lipid oxidation. Samples were evaluated for off-flavours with an electronic nose and a sensory analysis and for Totox value. Volatile compounds of fresh samples and samples subjected to storage test at 60°C were isolated with a static headspace technique. The results suggest that the electronic nose could help to supplement the sensory analysis. Models based on partial least-squares analysis were able to predict the oxidized flavour attribute of samples, with correlation coefficients ranging from 0.66 to 0.99. Based on elaborated methods and data treatment with PCA it was possible to distinguish between different food samples and monitor the formation of off-flavours associated with lipid oxidation.
An overview of lipids oxidation in foods, its main aspects and implications for the customer has ... more An overview of lipids oxidation in foods, its main aspects and implications for the customer has been outlined in a concise form. Three different mechanisms of fatty acid oxidation yielding different products are described: autoxidation, photo-oxidation and lipooxygenase action. Oxidation of sterols and fat-soluble vitamins (named A, D, E and K), all isoprenoic compounds, as a part of unsaponificable fraction of lipid are included to review. It is indicated that relatively little information exists on oxyphytosterols. The contents of these compounds in food products are presented. The crucial significance for the sensory aspect of food quality is ascribed to volatiles from lipid oxidation products. Some volatiles with low odour threshold are characterized. Nutritional problem of lipid oxidation products and products obtained by interactions with other food components is discussed. Use of antioxidants as important factors in reducing the risk of chronic diseases and its economical aspects is discussed. The need for search of natural antioxidant, commonly perceived as safe is stressed. Last part of review covers the methods for the assessment of lipid oxidation. Classic methods for the determination of lipid stability, for the measurement of lipid oxidation are described. Also chromatographic analyses of volatile compounds generated in the lipid oxidation process included static, dynamic head space and SPME are discussed. The novel approaches to the analysis of these volatiles such as chemometrical methods and electronic noses are also presented.
The effect of wheat kernel medium supplementation with octanoic acid on the formation of PR toxin... more The effect of wheat kernel medium supplementation with octanoic acid on the formation of PR toxin and some volatiles by Penicillium roqueforti was investigated. Octanoic acid was added to the medium once, prior to inoculation (4.55 mg g-1), or periodically (total 27.3 mg g-1) during the 10 day course of incubation. No octanoic acid was added to the reference sample. Levels of 2-heptanone, 2-heptanol and aristolochene, a volatile intermediate in PR toxin biosynthesis, were monitored using a solid phase microextraction (SPME) technique. The contents of PR toxin and ergosterol were determined after incubation. Aristolochene was observed in the reference sample, and 10.4 mg kg-1 of PR toxin was detected after 10 days. In cultures periodically supplemented with octanoic acid, no aristolochene or PR toxin were observed. However, in samples supplemented with octanoic acid only prior to incubation, the aristolochene level was 25% that in the reference sample, and PR toxin content was 3.4 mg kg-1. These data suggest that a high level of octanoic acid in the medium prevents PR toxin formation by P. roqueforti.
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Papers by Henryk Jeleń