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102
Volatile aroma compounds in Moskovskaya cooked smoked sausage
formed in different types of casings
Anastasia A. Semenova* , Andrey N. Ivankin , Tatyana G. Kuznetsova , Andrei S. Dydykin , Viktoria V. Nasonova , and Elena V. Mileenkova
V.M. Gorbatov Federal Research Centre for Food Systems of Russian Academy of Sciences, Moscow, Russia
* e-mail: [email protected]
Received March 20, 2018; Accepted in revised form February 13, 2019; Published June 08, 2019
Abstract: The paper presents a study of Moskovskaya cooked smoked sausages formed in various artificial casings: fibrous (cellulose), collagen, and polyamide. An oxygen permeability oxygen permeability of the casings was above 40 cm3 and below 30 cm3/m2-24 h-bar. The study involved a sensory evaluation and instrumental tests using a VOCmeter multi-sensor system ('electronic nose') and a 7890A gas chromatograph with a 5975C VLMSD mass-selective detector (Agilent Technologies). We obtained original data on the qualitative composition and the quantitative content of substances that form the aroma of cooked smoked sausages in various types of casings. We found that the samples contained two groups of compounds with the chemical formulas of CH^ and CiHiO/Nm. They had a ratio of (12-33):1 and were, apparently, the most significant aromatic substances. The main class of identified compounds was carboxylic acid esters, accounting for 76.61-81.60% of the total substances. We established a correlation between the aroma intensity and the concentration of chlorine-containing and nitrogen-containing compounds (except amines, amides, nitriles, and hydrazides) in the gas phase. The results did not confirm our hypothesis about the influence of the casing type and its permeability on the development of oxidative processes in the production of cooked smoked sausages. The practical significance of the study lies in creating a database of over 200 aromatic compounds that allows for a deeper understanding of aroma formation processes in cooked smoked sausages. The database can be used to exert a purposeful technological influence on the quality indicators and create various flavour compositions to adjust the sensory properties of the product.
Keywords: Flavours of meat products, sensory evaluation, 'electronic nose', gas chromatographic analysis, artificial casings
Please cite this article in press as: Semenova A.A., Ivankin A.N., Kuznetsova T.G., et al. Volatile aroma compounds in Moskovskaya cooked smoked sausage formed in different types of casings. Foods and Raw Materials, 2019, vol. 7, no. 1, pp. 168-176. DOI: http://doi.org/10.21603/2308-4057-2019-1-168-176.
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Foods and Raw Materials, 2019, vol. 7, no. 1
E-ISSN 2310-9599 ISSN 2308-4057
Research Article Open Access
DOI: http://doi.org/10.21603/2308-4057-2019-1-168-176 Available online at http:jfrm.ru
INTRODUCTION
In recent decades, sausage producers have significantly expanded the range of casings for cooked, smoked, and cooked smoked sausages. The latter are highly popular, especially in the summer, due to their sensory characteristics, high nutritional value, long shelf-life, and a relatively low price compared to expensive dry sausages [1, 2]. Aroma is one of the key factors of consumer preference [3-9]. The classical technology of making cooked smoked sausages involves a fairly long cooking process that includes boiling, cooling, smoking (one or two stages), and drying. Such a process demands using only permeable casings [10-12]. Artificial casings made of collagen, cellulose, and polyamide are widely used by modern
producers for various reasons. Some of them include standard characteristics of steam and gas permeability, as well as geometrical dimensions, which allow for automatic sausage forming [13]. Growing competition forces sausage producers to focus on technology, rather than the price or outcome, when choosing casings. In particular, they look at the effect that technology has on the product's sensory characteristics [14]. In this regard, of great scientific and practical interest is a study that aims to objectively assess the composition of volatile substances in the aroma of cooked smoked sausages formed in various types of artificial casings.
STUDY OBJECTS AND METHODS
Our objects of study were samples of Moskovskaya
Copyright © 2019, Semenova et al. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material for any purpose, even commercially, provided the original work is properly cited and states its license.
cooked smoked sausage (whole sausages) produced by the same shift on the same day according to State Standard R 55455-2013. Boiled-smoked meat sausages. Specifications*. The sausages were formed in the following casings: sample no. 1 in a fibrous (cellulose) casing, sample no. 2 in a collagen casing, sample no.
3 in a highly permeable polyamide with an oxygen permeability above 40 cm3/m2-24 h-bar, and sample
4 in a permeable polyamide casing with an oxygen permeability less than 30 cm3/m2-24 h-bar.
All the samples were produced at a sausage factory. After cooling, they were packed in impermeable bags to preserve their aroma and sent to V.M. Gorbatov Federal Research Centre for Food Systems.
The sensory evaluation of sausages was carried out according to State Standard 9959-2015**. The taste panel consisted of 7 qualified experts. The results were confirmed by instrumental sensory data produced by the VOCmeter ('electronic nose'). The device is equipped with highly sensitive nanosensors capable of capturing volatile components released from the surface of the product. Prior to testing, the sausages were crushed and at least three 3 g samples were taken from each of them. The samples were placed in special vials and sealed. The vials were alternately placed into the chamber, where each sample was heated to 50°C. Then, the lid of the vial was punctured with a needle, and the gas phase was taken from near the sample surface. The gas phase entered the surface of the nanosensors sensitive to various classes of chemical compounds. Any physicochemical changes that occurred on the surface of the nanosensors were converted into an electronic signal, transmitted to a computer, and statistically processed by the software. We used four metal oxide nanosensors (M1-M4) sensitive to those aroma-producing volatile substances which are characteristic of meat products. They include products of protein breakdown, fat oxidation, ketones, aldehydes, volatile fatty acids, ammonia and other substances [15-16].
The composition of volatile aroma components was analysed by a 7890A gas chromatograph with a 5975C VLMSD mass-selective detector (Agilent Technologies, USA). For this, volatile substances were preliminarily extracted (1:1) with 40% aqueous ethanol and chloroform-methanol according to the Folch method, followed by methylation with a solution of acetyl chloride in methanol. The composition of aroma components was determined by a HP-5MS capillary column with a diameter of 0.25 mm, a length of 30 m, and a stationary phase layer thickness of 0.25 |um.
The chromatography was carried out under the following conditions:
- carrier gas: He;
- flow rate: 1 ml/min;
- injector temperature in a no-split mode: 250°C;
- initial temperature of the column thermostat: 100°C for 2 minutes:
* State Standard R 55455-2013. Boiled-smoked meat sausages. Specifications. Moscow: Standartinform Publ., 2014. 14 p.
** State Standard 9959-2015. Meat and meat products. General conditions of organoleptical assessment. Moscow: Standartinform Publ., 2016. 20 p.
- programmable heating from 100°C to 290°C at a rate of 20°C/min;
- an isotherm at 290°C: up to 25 min; and
- component analysis duration: 25 min.
The identification parameters were as follows:
- ion source temperature: 230°C;
- quadrupole temperature: 150°C;
- electron energy: 70 eV;
- scan mode: full; and
- mass range: 33-1050 amu.
The peaks were analysed using the NIST08 MS Library, an automated search and identification database, and the substances were named according to the IUPAC. The analysis covered those substances whose mass content in the mixture of volatile compounds exceeded 0.01%. The probability of peak correlation had to be at least 35% [17].
RESULTS AND DISCUSSION
The sensory evaluation of the Moskovskaya sausage samples in various casings did not reveal any significant differences in their consistency, colour, taste, or aroma. The tasters noted a more pronounced smoking aroma in samples no. 2 and 3, compared to samples no. 1 and 4, and a firmer surface layer in samples no. 1 and 2. They did not establish any differences in taste and aroma between samples no. 1, 2, and 3; however, they found them less pronounced in sample no. 4.
The 'electronic nose' was used to quantitatively identify the minimum differences in the gas phase aroma (Fig. 1).
The highly sensitive nanosensors revealed no significant differences in aroma between the samples. This was evidenced by the general nature of nanosensor responses, with the strongest signal coming from M4 and M2. Moreover, there was an image resembling a geometric figure and no intersection between the lines connecting the scale points that corresponded to the
Ml
M3
M2
M4
no. 1 no. 2
no. 3 no. 4
Fig. 1. Multisensory aroma profiles of Moskovskaya sausage samples produced by the 'electronic nose'.
signals of the four nanosensors. The multisensory profiles of samples no. 2 and 3 practically coincided, indeed.
The analysis of sample no. 1 showed stronger signals coming from M2 and M4. These nanosensors are sensitive to the presence of aldehydes, ketones, and heterocyclic aromatic compounds in the gas phase. This
might result from more intensive oxidative processes and/or an increased concentration of volatile substances due to a rapid loss of moisture during heat treatment. Another reason might be a more intensive accumulation of substances that enter the product through the casing during smoking.
Table 1. Identification and analysis of major volatile substances in Moskovskaya sausage formed in a fibrous casing (sample no. 1)
Mass scanning
§ H
3 s
u -rs
Ph H
■S 'S
M
I
<u
3
£ E c
0s
1 * <5 a
Substance
c 0s
"S C
0 2
° Ë
o a
Probability of peak identification for
standard mass spectrum, %
1 2 3 4 5 6 7 8 9 10 11
2 8.196 862 869 880 1,582 2,171 0.20 0.10 4,6-Dimethyl-2-thioxo-1,2-dihydro-3-pyri- 50
dinecarbonitrile
3 8.300 880 889 904 854 2,101 0.19 0.10 4-Acetamido-N,N-diisobutyl-3-nitroben- 50
zamide
4 9.841 1,171 1,186 1,195 773 1,870 0.17 0.09 2-Pyrroline-3-carboxylic acid, 4-(4-chloro- 46
benzylidene)-2-methyl-5-oxo-, methyl ester
5 10.884 1,375 1,387 1,399 3,141 4,046 0.37 0.19 2-Chloro-N-(1-m-tolyl-2,3-dihydro-1H-pyr- 38
rolo[2,3-b]quinolin-4-yl)-acetamide
6 12.160 1,621 1,633 1,642 2,296 3,677 0.34 0.17 3-Bromo-N'-(1-(2-thienyl)ethylidene)benzo- 80
hydrazide
7 12.243 1,642 1,649 1,660 10,315 11,495 1.06 0.54 Methyltetradecanoate 87
8 12.383 1,660 1,676 1,687 33,372 33,679 3.10 1.57 2H-1-Benzopyran-2-one, 7-(4-methyl-5-phe- 64
nyl-2H-1,2,3-triazol-2-yl)-3-phenyl-
9 13.519 1,879 1,895 1,909 14,416 21,256 1.96 0.99 9-Hexadecenoic acid, methyl ester, (Z)- 50
10 13.665 1,909 1,923 1,948 233,070 255,890 23.54 11.92 Pentadecanoic acid, 14-methyl-, methyl ester 95
11 13.960 1,963 1,980 1,996 7,701 9,879 0.91 0.46 Ether, methyl 1-tetradecenyl 50
12 14.163 2,005 2,019 2,035 1,730 3,353 0.31 0.16 10-Undecynoic acid, methyl ester 52
13 14.292 2,035 2,044 2,056 1,941 2,571 0.24 0.12 Heneicosanoicacid, methyl ester 50
14 14.443 2,056 2,073 2,089 1,233 3,928 0.36 0.18 Hydrazine, 1,1-diethyl-2-(1-methylethyl)- 47
15 14.817 2,119 2,145 2,158 605,268 1,087,059 100.00 50.65 9-Octadecenoic acid (Z)-, methyl ester 99
16 14.936 2,158 2,168 2,185 131,811 155,923 14.34 7.26 Octadecanoic acid, methyl ester 98
17 15.055 2,185 2,191 2,197 1,997 4,288 0.39 0.20 Ethanol, 2-[(2-ethylhexyl)oxy]- 91
18 15.112 2,197 2,202 2,212 2,377 4,235 0.39 0.20 Silane, triethyl-2-pentenyl-, (Z)- 38
19 15.200 2,212 2,219 2,233 6,390 9,057 0.83 0.42 Octadec-9-en-1-al dimethyl acetal 53
20 15.335 2,236 2,245 2,269 516 2,632 0.24 0.12 Acetamide, N-(4-hydroxycyclohexyl)-, trans- 37
22 15.834 2,335 2,341 2,347 4,034 7,132 0.66 0.33 1-Chlorosulfonyl-3-methyl-1-azaspiro[3.5] 80
nonan-2-one
23 15.942 2,347 2,362 2,383 60,559 104,085 9.57 4.85 10-Undecenoyl chloride 43
24 16.083 2,383 2,389 2,407 2,145 7,197 0.66 0.34 Pentanoic acid, methylester 35
25 16.492 2,461 2,468 2,479 766 1,853 0.17 0.09 1,2-Ethanediamine, 47
N,N,N'-trichloro-N',1,1,2,2-pentafluoro-
26 16.658 2,482 2,500 2,509 843 1,893 0.17 0.09 Cyclohexasiloxane, dodecamethyl- 37
28 17.042 2,569 2,574 2,617 36,177 71,967 6.62 3.35 2-Methyl-3,4,5,6-tetrahydropyrazin 84
30 18.692 2,884 2,892 2,911 825 2,221 0.20 0.10 Perhydro-htx-2-one, 2-depentyl-, acetate ester 38
32 19.383 3,016 3,025 3,034 699 1,891 0.17 0.09 5H-Cyclopropa[3,4]benz[1,2-e] 43
azulen-5-one, 9,9a-bis(acety-
loxy)-1,1a,1b,2,4a,7a,7b,8,9,9a-decahydro-2,4
39 22.631 3,640 3,651 3,670 4,500 16,866 1.55 0.79 Ledeneoxide-(II) 38
40 22.869 3,691 3,697 3,712 553 1,697 0.16 0.08 4-(3,4-Methylenedioxyphenyl)-2-butanone 46
41 23.035 3,718 3,729 3,736 757 1,644 0.15 0.08 Silanamine, N-[2,6-dimeth- 43
yl-4-[(trimethylsilyl)oxy]
phenyl]-1,1,1-trimethyl-
43 23.705 3,847 3,858 3,862 664 1,689 0.16 0.08 N-Methyl-1-adamantaneacetamide 35
44 23.954 3,898 3,906 3,922 583 2,230 0.21 0.10 2,4-Di-tert-butyl-6-(tert-butylamino)phenol 37
47 24.332 3,970 3,979 3,988 823 2,468 0.23 0.12 11H-Dibenzo[b,e][1,4]diazepin-11-one, 49
5,10-dihydro-5-[3-(methylamino)propyl]-
Semenova A.A. et al. Foods and Raw Materials, 2019, vol. 7, no. 1, pp. 168-176 Table 2. Identification and analysis of major volatile substances in Moskovskaya sausage formed in a collagen casing (sample no. 2)
Mass scanning t, ht 3 c o ^ Substance Probability
.5 Start Max. Finish ig a, ^ £ t S of peak iden-
c c S '53 h o Sa 1 g S g tification for
■iS <u ^ E <D c "S s standard mass
<u PH H <U £ PH a <u PH rS O O rS O o spectrum, %
1 2 3 4 5 6 7 8 9 10 11
2 4.040 58 68 82 540 2,314 0.37 0.18 Butyric acid, 4-(4-chloro-5-methyl-3-nitro- 35
pyrazol-1-yl)-
5 8.196 853 869 877 903 1,803 0.29 0.14 Indolizine, 6-ethyl-2-phenyl- 47
6 8.300 877 889 898 1,422 2,272 0.37 0.18 2,3,4-Trimethoxyphenylacetonitrile 64
7 9.841 1,168 1,186 1,195 885 2,408 0.39 0.19 [5-[(Furan-2-carbonyl)amino]-3-methylpy- 60
razol-1-yl]acetic acid, ethyl ester
8 10.878 1,357 1,386 1,405 2,961 5,092 0.83 0.40 p-Pentyloxybenzylidene p-hexylaniline 53
9 12.155 1,603 1,632 1,642 2,568 4,091 0.66 0.32 Benzaldehyde, 2-(2-phenoxyethoxy)-, 1-cy- 45
clohexylsemicarbazone
10 12.243 1,642 1,649 1,657 6,230 6,647 1.08 0.52 Pentanoic acid, 4-methyl-, methyl ester 72
11 12.388 1,663 1,677 1,687 64,541 61,950 10.04 4.81 2H-1-Benzopyran-2-one, 7-(4-methy-5- 72
phenyl-2H-1,2,3-triazol-2-yl)-3-phenyl-
12 13.519 1,882 1,895 1,909 7,860 12,314 2.00 0.96 9-Octadecenoic acid (Z)-, methyl ester 53
13 13.659 1,909 1,922 1,936 125,948 139,968 22.68 10.87 Hexadecanoic acid, methylester 95
14 13.955 1,960 1,979 1,993 6,428 9,077 1.47 0.71 Butanoic acid, 2-hexenyl ester, (E)- 50
16 14.292 2,026 2,044 2,050 1,217 2,335 0.38 0.18 Undecanoic acid, methyl ester 64
17 14.443 2,065 2,073 2,086 1,732 3,725 0.60 0.29 Ethane, isothiocyanato- 43
19 14.801 2,116 2,142 2,158 367,029 617,113 100.00 47.91 9-Octadecenoic acid (Z)-, methyl ester 99
20 14.931 2,158 2,167 2,182 74,923 96,174 15.58 7.47 Octadecanoicacid, methyl ester 94
22 15.112 2,194 2,202 2,209 3,697 4,520 0.73 0.35 Silane, triethyl-2-pentenyl-, (Z)- 50
23 15.195 2,209 2,218 2,227 5,201 6,583 1.07 0.51 1-Hexadecen-3-ol, 3,5,11,15-tetramethyl- 43
24 15.740 2,314 2,323 2,335 5,643 8,862 1.44 0.69 4-Hexadecen-6-yne, (E)- 53
26 15.932 2,350 2,360 2,383 30,041 46,693 7.57 3.63 Hexadecanoic acid, 2-hydroxy-1-(hy- 46
droxymethyl)ethyl ester
27 16.077 2,383 2,388 2,404 1,063 2,428 0.39 0.19 Dodecanoic acid, 2-methyl- 52
29 16.767 2,509 2,521 2,527 1,697 2,520 0.41 0.20 Silane, triethyl-2-pentenyl-, (Z)- 72
30 16.923 2,533 2,551 2,563 49,234 103,407 16.76 8.03 9-0xabicyclo[6.1.0]nonane 86
31 17.032 2,563 2,572 2,611 14,819 44,786 7.26 3.48 Oxalic acid, isobutyl tridecyl ester 35
37 18.983 2,944 2,948 2,962 553 1,810 0.29 0.14 trans-2,3-Methylenedioxy-b-methyl-b-ni- 53
trostyrene
38 19.180 2,977 2,986 3,013 1,353 6,405 1.04 0.50 4-Piperidineacetic acid, 1-acetyl-5-eth- 38
yl-2-[3-(2-hydroxyethyl)-1H-indol-2-yl]-.
alpha.-methyl-, methyl ester
39 19.585 3,055 3,064 3,082 669 2,209 0.36 0.17 4,6-Bis(diethylamino)-1,3,5-triazine-2-car- 43
bonylhydrazide
44 21.515 3,421 3,436 3,442 978 3,758 0.61 0.29 N-Methyl-1-adamantaneacetamide 40
The statistical processing of the nanosensor signals showed the following multisensory profile areas that characterized the intensity of the samples' aroma (S107, cu, P > 0.95): 179.06; 118.91; 106.51; and 84.87 for samples no. 1, 2, 3, and 4, respectively. Thus, if we take the aroma intensity of sample no. 4 (minimum value) as 100%, the intensity of samples no. 1, 2, and 3 was 211%, 140%, and 125%, respectively. These differences indicated a need for further analysis of volatile substances.
It is noteworthy that it was the first study into the composition of volatile components in cooked smoked sausages. The most studied aroma is that of fermented raw and dry sausages [3-6]. Moskovskaya cooked smoked sausage is only made of beef and fatback, as well as a nitrite-curing mixture, sugar, and spices (black pepper, cardamom or nutmeg). Therefore, it was an
excellent model for studying aroma in this type of meat products.
Tables 1-4 present the identification and statistical processing results for volatile substances in the sausage samples obtained with the gas chromatograph software and the automated search and identification database [22].
We used the NIST08 MS Library automated database to identify volatile substances with a peak correlation probability of more than 35%. Of total volatile substances, we identified 85.9; 93.31; 94.43; and 93.72% of substances in samples no. 1, 2, 3, and 4, respectively. These amounts corresponded to the peaks presented in Tables 1-4.
The atomic composition of the identified volatile substances contained 10 elements from Mendeleev's Periodic Table, including hydrogen, carbon, oxygen, and nitrogen. These elements are the most typical in
Table 3. Identification and analysis of major volatile substances in Moskovskaya sausage formed in a highly permeable polyamide casing (sample no. 3)
Mass scanning , o ^ Substance Probability
. S ig a, ^ ¡Ü % 5 of peak iden-
c p S '53 ■c i5 ! is I E O o 13 § ^ p tification for
■iS <u Pp H ! K S 2 is ini PH <U £ Ph O <U 2 Pp o S s rS O o standard mass spectrum, %
1 2 3 4 5 6 7 8 9 10 11
2 4.128 76 85 103 410 1,452 0.30 0.15 Iron, (2-formyl norbornadiene)tricarbonyl 35
3 10.883 1,372 1,387 1,396 817 1,518 0.31 0.15 1,3-Dimethyl-7-O-tolyl-5,5-bis-trifluoro- methyl-5,8-dihydro-1H-pyrimido[4,5-d] pyrimidine-2,4-dione 45
5 12.238 1,642 1,648 1,660 3,520 4,767 0.97 0.48 Nonanoic acid, methyl ester 59
6 12.378 1,660 1,675 1,684 9204 11,033 2.24 1.12 1,2,3,4-Tetrahydroisoquinolin-6,7-diol, 1-phenylmethylene-, 2,6,7-triacetate 59
7 13.514 1,876 1,894 1,903 5,305 6,745 1.37 0.69 4-Nonenoic acid, methyl ester 42
8 13.654 1,909 1,921 1,948 111,673 120,593 24.53 12.25 Tridecanoic acid, methyl ester 97
12 14.796 2,119 2,141 2,158 300,232 491,592 100.00 49.92 9-Octadecenoic acid, methyl ester, (E)- 99
13 14.925 2,158 2,166 2,185 79,623 90,670 18.44 9.21 Octadecanoic acid, methyl ester 97
15 15.195 2,209 2,218 2,230 1,689 2,793 0.57 0.28 Pentanoic acid, 5,5-dimethoxy-, methyl ester 50
18 15.735 2,311 2,322 2,329 2,962 4,410 0,90 0.45 Methyl 3-hydroxyoctadec-9-enoate 74
20 15.927 2,350 2,359 2,383 25,335 41,069 8.35 4.17 15-Hydroxypentadecanoic acid 50
21 16.077 2,383 2,388 2,401 1,211 2,480 0.50 0.25 Methyl 18-methylnonadecanoate 43
24 16.923 2,530 2,551 2,566 43,792 92,020 18.72 9.34 9,17-Octadecadienal, (Z)- 42
25 17.032 2,566 2,572 2,632 12,672 32,128 6.54 3.26 Undecanoylchloride 35
27 18.371 2,827 2,830 2,851 749 3,101 0.63 0.32 Phenol, 4-[2-(5-nitro-2-benzoxazolyl) ethenyl]- 43
29 18.692 2,869 2,892 2,893 764 3,392 0.69 0.34 Alanine, 3,3,3-trifluo-ro-2-[(4-methoxybenzoyl) amino]-N-[3-(trifluoromethyl)-2-quinoxalinyl]-, ethyl ester 38
31 18.843 2,911 2,921 2,929 680 2,007 0.41 0.20 1,2-Benzenediol, O,O'-di(propargyloxycarbonyl)- 35
36 19.408 3,025 3,030 3,040 811 1,638 0.33 0.17 1,2,4-Benzenetricarboxylic acid, 1,2-dimethyl nonyl ester 35
42 20.84 3,298 3,306 3,313 556 1,507 0.31 0.15 1,2-Bis(trimethylsilyl)-3,6-dimethylcyclo-hexane-1,4-diene 47
43 21.224 3,373 3,380 3,388 703 1,999 0.41 0.20 2,6-Naphthalenediol, 1,5-bis[(piperonylimino)methyl]- 35
46 22.605 3,634 3,646 3,670 2,024 9,306 1.89 0.95 Benzamide, 3-me- thoxy-N-[4-(1-methylcyclopropyl) phenyl]- 43
48 23.29 3,769 3,778 3,790 558 1,665 0.34 0.17 Benzamide, N-(1,1-dimethylethyl)-4-me-thoxy- 47
products of animal and plant origin with a cellular structure. Also present were chlorine, sulphur, silicon, fluorine, bromine, and iron (Table 5).
The presence of organosilicon compounds was due to the use of a capillary column based on (5%-phenyl)-methylpolysiloxane. This group of compounds accounted for 0.36% to 0.64% of total volatile substances. Due to their origin and insignificant amount, they were excluded from further analysis.
As can be seen from Table 5, all the studied samples contained two groups of compounds with the general chemical formulas of CiHkOl and CiHkOlNm. Apparently, they were the most significant compounds in the aroma of Moskovskaya sausage. Their content was 33:1, 12:1, 32:1, and 25:1 in samples no. 1, 2, 3, and 4, respectively, which could be summarized as 12-33:1.
The greatest variety of compounds was found in sample no. 1 (fibrous casing) and sample no. 4 (permeable polyamide casing). The total amount of oxygen-containing compounds was slightly higher in sample no. 3 (highly permeable polyamide casing) than in sample no. 4 (polyamide casing with lower permeability). At the same time, the content of oxygen-containing compounds in sample 1 (fibrous casing) was 11.88% (absolute value) lower than in sample no. 3. Thus, the formation of a significant amount of oxygen-containing substances in the gas phase of a product could not be explained by the choice of casing or its degree of permeability.
Table 6 shows the content of volatile substances belonging to different classes of chemical compounds. As can be seen, carboxylic acid esters were the main
Table 4. Identification and analysis of major volatile substances in Moskovskaya sausage formed in a permeable polyamide casing (sample no. 4)
Mass scanning 3 Substance Probabili-
Start Max. Finish c c c ty of peak
. S ht ig a, "cS 0s identification
c n S ei h e are nt, pea e p S c n for standard
■is e PH <u H e Ph <U 2 PM o S K o g o a Ö c ° Ë O S mass spectrum, %
1 2 3 4 5 6 7 8 9 10 11
1 3.868 28 35 61 1,153 3,970 0.28 0.16 Benzeneethanamine, N-[(pentafluoro-phenyl)methylene]-4-[(trimethylsilyl) oxy]- 35
3 8.196 859 869 877 1,998 2,381 0.17 0.10 4,6-Dimethyl-2-thioxo-1,2-dihydro-3-pyridinecarbonitrile 50
4 8.3 883 889 904 1,594 2,321 0.17 0.09 2-Methyl-7-phenylindole 47
5 8.907 985 1,006 1,021 851 2,086 0.15 0.08 10-Undecynoic acid, methyl ester 72
6 9.846 1,171 1,187 1,201 580 1,671 0.12 0.07 1,2-Dihydroindeno[1,2,3-cd]pyrene 37
7 10.884 1,378 1,387 1,402 3,894 4,724 0.34 0.19 (6-Phenylsulfanyl-5-trifluoromethylpyri-din-3-yl)carbamic acid, prop-2-ynyl ester 50
8 11.408 1,474 1,488 1,501 624 1,748 0.12 0.07 2-p-Chlorophenyl-6,8-dimethyl-4-[1,2-epoxy-2-propyl]quinoline 35
10 12.248 1,639 1,650 1,663 12,357 14,835 1.06 0.59 Tridecanoic acid, 12-methyl-, methyl ester 83
11 12.388 1,663 1,677 1,690 90,045 84,605 6.04 3.37 2H-1-Benzopyran-2-one, 7-(4-methyl-5-phenyl-2H-1,2,3-triazol-2-yl)-3-phenyl- 59
12 12.959 1,768 1,787 1,795 807 2,070 0.15 0.08 Cyclopentanetridecanoicacid, methyl ester 53
13 13.519 1,876 1,895 1,903 18,196 25,427 1.82 1.01 9-Octadecenoic acid (Z)-, methyl ester 95
14 13.67 1,909 1,924 1,948 270,802 327,084 23.36 13.03 Pentadecanoic acid, 14-methyl-, methyl ester 97
15 13.96 1,963 1,980 1,990 6,884 10,126 0.72 0.40 trans-2-Decen-1-ol, methyl ether 50
16 14.158 2,005 2,018 2,026 1,961 3,616 0.26 0.14 2,4,3,5-Diethylidene-l-xylose 50
17 14.292 2,038 2,044 2,056 2,635 3,243 0.23 0.13 Dodecanoic acid, methylester 64
19 14.817 2,110 2,145 2,161 749,047 1,400,183 100.00 55.78 9-Octadecenoic acid (Z)-, methyl ester 99
20 14.936 2,161 2,168 2,182 137,725 172,630 12.33 6.88 Octadecanoicacid, methyl ester 97
21 15.05 2,182 2,190 2,194 1,853 4,677 0.33 0.19 Cyclopropanenonanoic acid, methyl ester 47
22 15.117 2,194 2,203 2,212 3,839 6,142 0.44 0.25 Silane, triethyl-2-pentenyl-, (Z)- 50
23 15.2 2,212 2,219 2,242 6,331 8,829 0.63 0.35 Phytol 38
24 15.745 2,317 2,324 2,335 6,674 10,928 0.78 0.44 5,8,11,14,17-Eicosapentaenoic acid, methyl ester, (all-Z)- 64
25 15.828 2,335 2,340 2,350 3,107 6,316 0.45 0.25 4-(6-Methyl-4-methylene-3,4,5,6-tetrahy-dro-2H-pyran-2-yl)-1-butanol 38
27 16.083 2,383 2,389 2,401 1,515 2,373 0.17 0.10 Pentanoicacid, methyl ester 58
31 16.933 2,530 2,553 2,563 96,726 174,952 12.49 6.97 9-0xabicyclo[6.1.0]nonane 86
32 17.037 2,563 2,573 2,605 26,231 67,728 4.84 2.70 Eicosanoic acid, 2-hydroxy-1-(hy-droxymethyl)ethyl ester 38
35 17,909 2,725 2,741 2,743 953 2,876 0.21 0.12 4-Dehydroxy-N-(4,5-methylenedi-oxy-2-nitrobenzylidene)tyramine 37
45 22,158 3,556 3,560 3,580 663 2,067 0.15 0.08 Benzamide, 4-me-thoxy-N-[4-(1-methylcyclopropyl) 35
phenyl]-
class of identified compounds in all the samples. Their mass fraction in the total amount of identified substances ranged from 76.61% to 81.60%. Another 4 classes of compounds, present in all the samples, were represented less evenly. For example, the content of alcohols, oxygen-containing heterocycles (except ketones and aldehydes), and nitrogen-containing heterocycles (except heterocyclic amines, amides and hydrazides) ranged from 0.3% to 0.51%, 0.2% to 8.03%, and 0.26% to 5.02%, respectively.
A detailed analysis of the classes of substances present in the aroma of the samples, as well as their
elemental analysis, did not reveal any relationship between the type and permeability of the casing and the characteristics of volatile substances.
Carboxylic acid esters were mainly represented by methyl esters and less frequently by ethyl esters. On the one hand, this could be explained by the sample preparation method using methylation. On the other hand, methyl and ethyl esters could already be present in the product during its manufacture. The esters identified in the samples differed in their molecular weight, chain length, and the presence of not only carbon, hydrogen, and oxygen, but also nitrogen, chlorine, and fluorine.
Table 5. Atomic composition of volatile compounds in Moskovskaya sausage aroma
Chemical formula of Content of identified compounds,
identified compounds % of total amount
Sample
no. 1 no. 2 no. 3 no. 4
1 2 3 4 5
CiHk - 0.б9 - 0.07
CiHkNl 3.35 0.14 - 0.09
C.HN.F Cl i k l m n 0.09 - - -
CiHkNlSm - 0.29 - -
C.HN.S Si i k l m n 0.10 - - 0.10
Ci HO 74.12 84.4б 87.41 89.12
CH 0,Cl i k l m 4.85 - 3.2б -
c. hon i k l m 2.27 7.00 2.7б 3.57
CH ON Br S Si i k l m n p q 0.17 - - -
CiHkOlNmCln i k l m n 0.28 0.18 - 0.07
CiHkOlNmFn i k l m n - - 0.49 -
CHON F Si i k l m n p - - - 0.1б
CHON S Cl i k l m n p CH ON S F i k l m n p 0.33 - - -
- - - 0.19
CHON Si i k l m n 0.08 - - -
CHkOlSm - - 0.10
CiHk°lSim 0.09 - - -
CHOFe i k l m - - 0.15 -
CHSi i k l 0.20 0.55 0.3б 0.25
Total identified com- 85.93 93.31 94.43 93.72
pounds
Including compounds
containing:
- oxygen 82.19 91.б4 94.07 93.21
- nitrogen б.б7 7.б1 3.25 4.18
- chlorine 5.55 0.18 3.2б 0.07
- sulphur 0.б0 0.29 - 0.39
- silicon 0.б4 0.55 0.3б 0.51
- fluorine 0.09 - 0.49 0.35
In total, we found over 35 compounds with a number of carbon atoms from 6 to 23. The most represented in all the samples were the methyl esters of oleic acid with the number of carbon atoms С19 (Table 7). The predominance of this ester was due to the fatty acid composition of fatback: the content of this monounsaturated acid ranged from 30% to 45% of the total fatty acids.
We were mostly interested in those groups of substances which were found in all Moskovskaya sausage samples as a result of the sensory evaluation and the "electronic nose" tests. The data allowed us to check our hypothesis about a correlation between the aroma intensity established by the "electronic nose" and the total content of substances in the gas phase of the samples (Table 8).
The correlation analysis produced an unexpected result: an increase in the aroma intensity was proportional to the increase in the content of nitrogen-containing heterocycles and chlorine-containing substances. In that case, it was reasonable to consider only positive values of the correlation coefficients, since the hypothesis that the nanosensor signals increased as the concentration of certain substances decreased had no physical sense.
Table 6. Major classes of chemical compounds in Moskov-skaya sausage aroma
Class Content of compounds by class,
% of total amount
Sample
no. 1 no. 2 no. 3 no. 4
1 2 3 4 5
Hydrocarbons
alkanes - 0.98 - -
arenes - 0.14 - 0.07
Oxygen-containing
alcohols 0.3 0.51 0.32 0.45
aldehydes - - 9.34 -
carboxylic acid - 0.18 4.17 -
esters 77.9 7б.б1 77.5 81.б0
heterocyclic aldehydes -(including nitro- 0.32 0.14
gen-containing)
heterocyclic ketones 0.б2 0.15 3.37
(including nitro-
gen-containing)
other oxygen-contai- 0.79 8.03 0.2 7.22
ning heterocycles
Nitrogen-containing
amines 0.09 0.4 - 0.12
amides 0.08 0.29 - -
hydrazines 0.18 - - -
nitriles - 0.18 - -
heterocyclic amines - - - 0.1б
heterocyclic amides 0.41 - 1.12 0.08
heterocyclic hydrazides 0.17 0.17 - -
other nitrogen-contai - 5.02 4.95 1.12 0.2б
ning heterocycles
Iron-containing
heterocycles - - 0.15 -
Total (without sili- 85.29 92.7б 94.07 93.21
con-containing compounds)
CONCLUSION
The study produced original data on the qualitative composition and the quantitative content of substances that form the aroma of Moskovskaya cooked smoked sausage. It involved a detailed comparative analysis of the main classes of compounds present in the gas phase of the samples formed in various types of casings. We found that all the samples contained two groups of compounds with the general chemical formulas of CH^O, and CHPN*. With a ratio of (12-33):1, they appeared to be the most significant in the formation of the Moskovskaya sausage aroma. Furthermore, we established that carboxylic acid esters were the main class of compounds identified in all the samples. Their mass fraction ranged from 76.61% to 81.60% of the total substances.
The data revealed no relationship between the oxidative processes and the degree of casing permeability. The correlation analysis identified the main chemical compounds that increase the intensity of cooked smoked sausages.
The practical significance of the study lies in creating a database of over 200 aromatic compounds.
Semenova A.A. et al. Foods and Raw Materials, 2019, vol. 7, no. 1, pp. 168-176 Table 7. Elemental composition of esters identified in the gas phase of Moskovskaya sausage samples
Ci in the Chemical formula of identified esters Total amount of esters with Ci in the gas phase of samples,
ester % of total substances
molecule Sample no. 1 Sample no. 2 Sample no. 3 Sample no. 4
1 2 3 4 5 1
c6h12o2 c7h14o2
C8Hl6O4
Cl0Hl8O2' Cl0H20O2
C„H19C1°, CiiH2iCl°, CiiH22°
C12H20O2, C12H24O2 C13H15N3O4' C13H24°2= C13H26O2 C14H10°6 > C14H12C1NO3' C14H28°2 C15H30°, C15H30°2 C16HllF3N2O2S' C16H27N°3 Cl7H32O2, Cl7H34O2 Cl9H36O2, Cl9H36O3, Cl9H36O4, C20H28°6, C20H40°2 C2lH32O2, C2lH42O2 C22Hl8F6N4O4' C22H44°2 C23H32N2O4' C23H46O4
Cl9H38O2, Cl9H38O4
0.34
4.85 0.16
0.09 l.00 0.10 l2.9l 57.91 0.42
0.12
0.52
0.7l
0.18 0.38
10.87 63.45
0.5
0.28 l.l7 3.26
12.45
59.58 0.17 0.25 0.34
0.l
0.4
0.08
0.32
0.59 0.19 13.03 63.75
0.44
2.7
C
6
C
7
C
8
C
10
C
ll
C
12
C
13
C
14
C
15
C
16
C
17
C
19
C
20
C
21
C
22
C
23
Table 8. Correlation coefficients between aroma intensity ('electronic nose') and groups of substances in the samples gas phase
Groups of substances in the product gas phase
Correlation coefficient between groups of substances and aroma intensity
l
2
Substances with the general formula Ci HkOl Substances with the general formula
C, HPNm
All oxygen-containing substances incl. oxygen-containing heterocycles All nitrogen-containing substances incl. nitrogen-containing heterocycles (except amines, amides, nitriles, and hydrazides)
All chlorine-containing substances
Alcohols
Esters
incl. esters with total carbons C19
-0.9932 -0.2812
-0.9540 —0.5121 0.5812 0.7927
0.8128 -0.5419 -0.4805 -0.7561
This database allows for a deeper understanding of aroma formation processes in cooked smoked sausages under various technological conditions. As a result, we can exert a purposeful influence on the quality indicators and create various flavour compositions to adjust the sensory properties of the finished product.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
ACKNOWLEDGEMENTS
The authors are grateful to OOO Atlantis-Pak, a manufacturer of packaging materials, for supplying us with casings for the test samples of Moskovskaya cooked smoked sausage.
FUNDING
The study was carried out within the Centre's Research and Development Plan.
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ORCID IDs
Anastasia A. Semenova http://orcid.org/0000-0002-4372-6448 Andrey N. Ivankin https://orcid.org/0000-0002-6557-2697 Tatyana G. Kuznetsova https://orcid.org/0000-0002-5164-1807 Andrei S. Dydykin https://orcid.org/0000-0002-0208-4792 Viktoria V. Nasonova https://orcid.org/0000-0001-7625-3838 Elena V. Mileenkova https://orcid.org/0000-0001-5745-305X
