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Study of the Volatile Compounds Useful for the Characterization of Frozen Anchoita (Engraulis anchoita) by SPME-GC-MS
CHAPTER
32
Study of the Volatile Compounds Useful for the Characterization of Frozen Anchoita (Engraulis anchoita) by SPME-GC-MS Leila Q. Zepkaa, Roger Wagnera, Eduardo Jacob-Lopesa, Marina M. Daltoéb, Andriéli B. Santosa, Aiana F. Torria, Jossiê Z. Donadela and Maria I. Queirozb a
Department of Food Technology and Science, Federal University of Santa Maria (UFSM), Santa Maria, Brazil b Food and Chemistry School, Federal University of Rio Grande (FURG), Rio Grande, Brazil
32.1 INTRODUCTION A growing number of consumers want to eat seafood without feeling guilty. The fisheries chain must operate so that fishing can continue indefinitely without overexploiting the resource, and the productivity of the ecosystem is preserved [1]; thus, the study of underexploited species such as anchoita has become important. Fish and fish products fulfill an important role in human nutrition as a source of biologically valuable protein, fat, and fat-soluble vitamins. Freezing is an efficient way of storing fish, but nowadays consumer interest in fresh products is increasing [2]. In such products, aroma is a very important attribute, which can easily be altered by the length of storage. Thus, the aim of the present work was to study the formation of volatile compounds derived from frozen anchoita. In order to evaluate these modifications, anchoita (Engraulius anchoita) were submitted to 120 days of frozen storage at −20°C.
32.2 MATERIALS AND METHODS Anchoita were captured during cruises performed by the Federal University of Rio Grande ship, close to the limits of Brazil and Uruguay. After capture, the fish were stored on board in thermal receptacles containing equal proportions (1 : 1) of fish and ice/seawater. In the laboratory, anchoita were kept frozen at −20°C until analysis (after 120 days of storage). The peroxide value [3], the thiobarbituric acid-reactive substances (TBARS [4]) index and pH [5] of fish muscle were determined. V. Ferreira and R. Lopez (Eds): Flavour Science. DOI: http://dx.doi.org/10.1016/B978-0-12-398549-1.00032-5
© 2014 2013 Elsevier Inc. All rights reserved.
169
170
Leila Q. Zepka et al.
The volatile compounds were separated and tentatively identified by a mass spectrometry (HS-SPME-GC-MS). The volatile compounds were separated on a ZB-5 (Phenomenex, Torrance, USA) fused silica capillary column (30 m × 0.25 mm i.d. × 0.25 μm film thickness) in a Shimadzu model QP 2010 mass spectrometer (GC/MS) with a MS electron-impact ionization voltage of 70 eV. The splitless mode injector was maintained at 230°C and the flame ionization detector (FID) at 250°C. The carrier gas was helium, at a flow rate of 2.0 mL/min. The oven temperature was kept at 35°C for 2 minutes, followed by a linear increase of 2°C/min to 80°C, then an increase of 4°C/min to 150°C, and finally an increase of 8°C/min to a temperature of 230°C, held for 5 minutes. The MS spectra obtained were analyzed by matching with the computerized library, NIST 2006 MS Library, provided with the equipment. A standard mixture of paraffin homologues was prepared using hexane as solvent. Co-injection of the sample and standard mixture provided retention indices under the same chromatographic conditions, and also experimental Kovats retention indices.
32.3 RESULTS The development of oxidation products and pH value of anchoita muscle during frozen storage are listed in Table 32.1. The impact of freezing storage on the profile of volatile compounds formed in the anchoita can be seen in Figure 32.1 and Table 32.2. Analysis of stored anchoita samples using the SPME method allowed for identification of more than 40 volatile compounds.
32.4 DISCUSSION AND CONCLUSION Several alcohols (butanol, 2-cis-peten-1-ol, 1-hexanol, 1-octen-3-ol) and aldehydes (butanal, hexanal, heptanal, octanal, nonanal) were identified as potential markers for anchoita until 120 days of storage. Hexanal can be Table 32.1 Physico-Chemical Analysis of Frozen Anchoita Time (days) Componentsa
TBARS (mg malonaldehyde/kg) I.P. (meq O2/kg) pH a
0
18
28
60
120
0.2 ± 1.0
0.8 ± 0.8
0.9 ± 0.7
1.0 ± 0.5
1.5 ± 0.8
0.01 ± 0.8 6.1 ± 0.5
2.3 ± 0.8 6.2 ± 0.6
3.4 ± 0.6 6.2 ± 0.5
6.1 ± 0.7 6.3 ± 0.9
9.0 ± 0.5 6.3 ± 0.6
Averages of three independent determinations.
Study of the Volatile Compounds Useful for the Characterization of Frozen Anchoita
171
4,000,000 4
5
Intensity
1
2
3
10 12 14 16 9 11 13 15 19 6 8 18 7 17
21
27 23 28 29 22 24 26 30 20 25
0 0
10
20
32 34 35 37 36
39 38 41 42 43 40
30 Time (min)
40
44 45
50
60
Figure 32.1 Chromatogram (total ion current), obtained by GC-MS, of volatile compounds from frozen anchoita. See text for chromatographic conditions. Peak characterization is given in Table 32.2. Table 32.2 Principal Volatile Compounds Detected by GC-MS in Frozen Anchoita Peak Number Compound Kovats Index
3 4 5 6 7 8 9 10 11 12 13 14 18 23 25 26 27 29 32 36 38 42 44 45
Trimetilamina 1-Penten-3-ol 2,3-Pentadiona 2-Propanol, 1-dimethylamine Acetic acid 2-cis-Pent-enal 1-Pentanol 2-cis-Pent-enol 3-Hexenol 2,3 Hexadiona 2-Methyl-3-penten-1-ol Hexanal 2-cis-Hexenal 2-Heptanone Heptanal 1-Methylethyl-benzene 1-Octen-3-ol Pentane-5-carboxylic-acid, 1-methyl, ethyl ester 2-cis-Octen-1-ol Nonanal Decanal 2-Methyl-undecen-1-al Pentadecanol Hexadecanol
663 688 700 746 751 758 773 767 783 788 793 802 856 894 903 925 985 997 1071 1105 1205 1342 1773 1871
172
Leila Q. Zepka et al.
related to the fat acid composition of fish since it is formed by oxidation of linolenic acid [2], the most abundant fatty acid in cultured fish muscle. Other volatiles (acetic acid, propionic acid) were identified as potential markers for anchoita spoilage. In summary, SPME-GC-MS can be suggested as a useful tool for the evaluation of the effect of frozen storage on the volatile compounds of anchoita samples.
ACKNOWLEDGEMENT This work was supported by FAPERGS and CNPQ.
REFERENCES [1] J. Jacquet, D. Pauly, Seafood stewardship in crisis, Nature 467 (2010) 28–29. [2] J. Iglesias, I. Medina, F. Bianchi, M. Careri, A. Mangia, M. Musci, Study of the volatile compounds useful for the characterisation of fresh and frozen-thawed cultured gilthead sea bream fish by solid-phase microextraction gas chromatography-mass spectrometry, Food Chem. 115 (2009) 1473–1478. [3] R.H. Chapman, J. McKay, The estimation of peroxides in fats and oils by the ferric thiocyanate method, J. Am. Oil Chem. Soc. 26 (1949) 360–363. [4] W. Vincke, Direct determination of the thiobarbituric acid value in trichloracetic acid extracts of fish as a measure of oxidative rancidity, Fett. Wiss. Techn. 1 (1970) 84–87. [5] AOAC, Official Methods of Analysis, Association of Official Analytical Chemists, Gaithersburg, MD, 2000.
32
Study of the Volatile Compounds Useful for the Characterization of Frozen Anchoita (Engraulis anchoita) by SPME-GC-MS Leila Q. Zepkaa, Roger Wagnera, Eduardo Jacob-Lopesa, Marina M. Daltoéb, Andriéli B. Santosa, Aiana F. Torria, Jossiê Z. Donadela and Maria I. Queirozb a
Department of Food Technology and Science, Federal University of Santa Maria (UFSM), Santa Maria, Brazil b Food and Chemistry School, Federal University of Rio Grande (FURG), Rio Grande, Brazil
32.1 INTRODUCTION A growing number of consumers want to eat seafood without feeling guilty. The fisheries chain must operate so that fishing can continue indefinitely without overexploiting the resource, and the productivity of the ecosystem is preserved [1]; thus, the study of underexploited species such as anchoita has become important. Fish and fish products fulfill an important role in human nutrition as a source of biologically valuable protein, fat, and fat-soluble vitamins. Freezing is an efficient way of storing fish, but nowadays consumer interest in fresh products is increasing [2]. In such products, aroma is a very important attribute, which can easily be altered by the length of storage. Thus, the aim of the present work was to study the formation of volatile compounds derived from frozen anchoita. In order to evaluate these modifications, anchoita (Engraulius anchoita) were submitted to 120 days of frozen storage at −20°C.
32.2 MATERIALS AND METHODS Anchoita were captured during cruises performed by the Federal University of Rio Grande ship, close to the limits of Brazil and Uruguay. After capture, the fish were stored on board in thermal receptacles containing equal proportions (1 : 1) of fish and ice/seawater. In the laboratory, anchoita were kept frozen at −20°C until analysis (after 120 days of storage). The peroxide value [3], the thiobarbituric acid-reactive substances (TBARS [4]) index and pH [5] of fish muscle were determined. V. Ferreira and R. Lopez (Eds): Flavour Science. DOI: http://dx.doi.org/10.1016/B978-0-12-398549-1.00032-5
© 2014 2013 Elsevier Inc. All rights reserved.
169
170
Leila Q. Zepka et al.
The volatile compounds were separated and tentatively identified by a mass spectrometry (HS-SPME-GC-MS). The volatile compounds were separated on a ZB-5 (Phenomenex, Torrance, USA) fused silica capillary column (30 m × 0.25 mm i.d. × 0.25 μm film thickness) in a Shimadzu model QP 2010 mass spectrometer (GC/MS) with a MS electron-impact ionization voltage of 70 eV. The splitless mode injector was maintained at 230°C and the flame ionization detector (FID) at 250°C. The carrier gas was helium, at a flow rate of 2.0 mL/min. The oven temperature was kept at 35°C for 2 minutes, followed by a linear increase of 2°C/min to 80°C, then an increase of 4°C/min to 150°C, and finally an increase of 8°C/min to a temperature of 230°C, held for 5 minutes. The MS spectra obtained were analyzed by matching with the computerized library, NIST 2006 MS Library, provided with the equipment. A standard mixture of paraffin homologues was prepared using hexane as solvent. Co-injection of the sample and standard mixture provided retention indices under the same chromatographic conditions, and also experimental Kovats retention indices.
32.3 RESULTS The development of oxidation products and pH value of anchoita muscle during frozen storage are listed in Table 32.1. The impact of freezing storage on the profile of volatile compounds formed in the anchoita can be seen in Figure 32.1 and Table 32.2. Analysis of stored anchoita samples using the SPME method allowed for identification of more than 40 volatile compounds.
32.4 DISCUSSION AND CONCLUSION Several alcohols (butanol, 2-cis-peten-1-ol, 1-hexanol, 1-octen-3-ol) and aldehydes (butanal, hexanal, heptanal, octanal, nonanal) were identified as potential markers for anchoita until 120 days of storage. Hexanal can be Table 32.1 Physico-Chemical Analysis of Frozen Anchoita Time (days) Componentsa
TBARS (mg malonaldehyde/kg) I.P. (meq O2/kg) pH a
0
18
28
60
120
0.2 ± 1.0
0.8 ± 0.8
0.9 ± 0.7
1.0 ± 0.5
1.5 ± 0.8
0.01 ± 0.8 6.1 ± 0.5
2.3 ± 0.8 6.2 ± 0.6
3.4 ± 0.6 6.2 ± 0.5
6.1 ± 0.7 6.3 ± 0.9
9.0 ± 0.5 6.3 ± 0.6
Averages of three independent determinations.
Study of the Volatile Compounds Useful for the Characterization of Frozen Anchoita
171
4,000,000 4
5
Intensity
1
2
3
10 12 14 16 9 11 13 15 19 6 8 18 7 17
21
27 23 28 29 22 24 26 30 20 25
0 0
10
20
32 34 35 37 36
39 38 41 42 43 40
30 Time (min)
40
44 45
50
60
Figure 32.1 Chromatogram (total ion current), obtained by GC-MS, of volatile compounds from frozen anchoita. See text for chromatographic conditions. Peak characterization is given in Table 32.2. Table 32.2 Principal Volatile Compounds Detected by GC-MS in Frozen Anchoita Peak Number Compound Kovats Index
3 4 5 6 7 8 9 10 11 12 13 14 18 23 25 26 27 29 32 36 38 42 44 45
Trimetilamina 1-Penten-3-ol 2,3-Pentadiona 2-Propanol, 1-dimethylamine Acetic acid 2-cis-Pent-enal 1-Pentanol 2-cis-Pent-enol 3-Hexenol 2,3 Hexadiona 2-Methyl-3-penten-1-ol Hexanal 2-cis-Hexenal 2-Heptanone Heptanal 1-Methylethyl-benzene 1-Octen-3-ol Pentane-5-carboxylic-acid, 1-methyl, ethyl ester 2-cis-Octen-1-ol Nonanal Decanal 2-Methyl-undecen-1-al Pentadecanol Hexadecanol
663 688 700 746 751 758 773 767 783 788 793 802 856 894 903 925 985 997 1071 1105 1205 1342 1773 1871
172
Leila Q. Zepka et al.
related to the fat acid composition of fish since it is formed by oxidation of linolenic acid [2], the most abundant fatty acid in cultured fish muscle. Other volatiles (acetic acid, propionic acid) were identified as potential markers for anchoita spoilage. In summary, SPME-GC-MS can be suggested as a useful tool for the evaluation of the effect of frozen storage on the volatile compounds of anchoita samples.
ACKNOWLEDGEMENT This work was supported by FAPERGS and CNPQ.
REFERENCES [1] J. Jacquet, D. Pauly, Seafood stewardship in crisis, Nature 467 (2010) 28–29. [2] J. Iglesias, I. Medina, F. Bianchi, M. Careri, A. Mangia, M. Musci, Study of the volatile compounds useful for the characterisation of fresh and frozen-thawed cultured gilthead sea bream fish by solid-phase microextraction gas chromatography-mass spectrometry, Food Chem. 115 (2009) 1473–1478. [3] R.H. Chapman, J. McKay, The estimation of peroxides in fats and oils by the ferric thiocyanate method, J. Am. Oil Chem. Soc. 26 (1949) 360–363. [4] W. Vincke, Direct determination of the thiobarbituric acid value in trichloracetic acid extracts of fish as a measure of oxidative rancidity, Fett. Wiss. Techn. 1 (1970) 84–87. [5] AOAC, Official Methods of Analysis, Association of Official Analytical Chemists, Gaithersburg, MD, 2000.