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Food Additives & Contaminants Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfac19
Rapid method for the simultaneous GC quantitation of acids and sugars in fruits and vegetables a
Ibolya Molnár‐Perl & Magdolna Morvai
a
a
Institute of Inorganic and Analytical Chemistry, L. Eötvös University, PO Box 32, Budapest 112, H‐1518, Hungary Published online: 10 Jan 2009.
To cite this article: Ibolya MolnrPerl & Magdolna Morvai (1992) Rapid method for the simultaneous GC quantitation of acids and sugars in fruits and vegetables, Food Additives & Contaminants, 9:5, 505-514, DOI: 10.1080/02652039209374104 To link to this article: http://dx.doi.org/10.1080/02652039209374104
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sublicensing, systematic supply, or distribution in any form to anyone is expressly
Downloaded by [Purdue University] at 19:49 27 July 2013
forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
FOOD ADDITIVES AND CONTAMINANTS, 1992, VOL. 9, NO. 5, 505-514
Rapid method for the simultaneous GC quantitation of acids and sugars in fruits and vegetables IBOLYA MOLNÁR-PERL and MAGDOLNA MORVAI
Downloaded by [Purdue University] at 19:49 27 July 2013
Institute of Inorganic and Analytical Chemistry, L. Eötvös University, Budapest 112, PO Box 32, H-1518, Hungary Rapid methods of analysis for the simultaneous determination of acids and sugars in fruits and vegetables using trimethylsilylation and gas chromatography are reported. The methods have been shown to be generally applicable, rapid, simple and cheap. Typical applications are shown involving the determination of a range of organic acids and sugars in carrot, potato, cucumber, tomato, apple, pear, grape, strawberry and citrus fruits. Keywords: simultaneous analysis of acids and sugars, gas chromatography, trimethylsilyl derivatives, carrot, potato, cucumber, tomato, apple, pear, grape, strawberry, citrus fruits
Introduction
The goal of this compilation is to propagate the use of the trimethylsilylether/ester(TMS) and TMS-oxime derivatives in the qualitative and quantitative analysis of acids and sugars by gas chromatography(GC), of those acids and sugars which are present in almost all plants, fruits, vegetables, foods and food products as their main constituents. As to the relevancy of the topic, it is known how important can be the exact knowledge of the qualitative and quantitative distribution of the characteristic acids and sugars in various matrices. Namely, both their absolute amounts and/or the ratios of their amounts (i) can serve as a powerful tool to detect adulteration and/or presevatives in juices, ciders or in other fruit products, (ii) are indices to control the changes in the production and in the storage of fresh, frozen or canned products, and, (iii) are indicators in the evaluation of fruit maturity. The reason for the importance of this derivatization technique can be explained as follows: (a) the general applicability of the silylation technique to all compounds containing active hydrogen functions (—OH, —COOH, - S H , — NH2, —NH, —POH, -SOH); (b) the relatively slightly increased molecular weight of derivatized products compared to underivatized ones, a very important feature of this technique from the point of view of the higher molecular weight components, such as sugars with a degree of polymerization up to 5; (c) the simplicity (it is a rapid procedure, neither time consuming nor tedious); and, (d) the low cost of the method. 0265-203X/92 $3.00 © 1992 Taylor & Francis Ltd.
506
/. Molndr-Perl and M. Morvai
As can be seen, the examples (point (a)) cover almost all the main functional groups of organics which can be converted to the corresponding silyl derivatives (with the sole exception of the carbonyl group which has to be oximated prior to silylation). Finally, in connection with the general applicability of the silylation technique, one disadvantage of this derivatization procedure is to be emphasized: in order to get quantitative interactions, the optimum silylation parameters, which are considerably different for the various groups of organics, have to be followed strictly.
Downloaded by [Purdue University] at 19:49 27 July 2013
Materials and methods The materials and methods used are detailed elsewhere (Molnar-Perl and Pinter-Szakacs 1981, 1984, 1986, Molnar-Perl et al. 1985, 1990, Morvai and Molnar-Perl 1989, 1990, Morvai et al. 1991, Morvai et al. in press). Results
Taking into account the limitations detailed above and lack of literature data, there was a need for a really appropriate method for the analysis of sugars and acids, simultaneously, potentially present in matrices of interest. Thus, an exhaustive study was done (as a function of the composition and the quality of the silylating agent, time and temperature of interactions), in order to optimize the quantitative and competitive protocol with respect to both the silylation and GC conditions, and for all compounds listed (in tables 1-3 and/or in figures 1-6). As a result of our efforts we have added two new principles to this field: (a) the development of silylation and GC procedures, satisfactory for numerous compounds potentially present in matrices of interest, ensuring (i) quantitative silylation without any side reaction, (ii) within a reasonable reaction time (20 min) and temperature (125°C), and (iii) with a good reproducibility of the measurements; (b) the possibility of the quantification of compounds being present in extremely different concentration ranges (10~3-10% w/w) based on the discovery that the silylated solutions of acids and sugars can be evaporated, without any irreversible changes. (without going into details of previously published analytical aspects) are shown some concrete tasks, solved without exception with the GC analysis of silyl derivatives. As has been detailed in the introductory part of this compilation the unified procedure appropriate for the simultaneous measurement of numerous acids and sugars as TMS and/or TMS-oxime derivatives, from a single solution by one injection was developed. According to the task and the equipment and materials available, we optimized two programmes: the short programme (figure 1) can be suggested for the measurement of the main components and also for analysts having older apparatus and packed columns only. The long programme (figure 2, table 1) developed on a Chrompack CP 9000 apparatus using a fused silica capillary column of 10 m length can be recommended for special tasks needing also a knowledge of the amounts of trace constituents.
Downloaded by [Purdue University] at 19:49 27 July 2013
Detection of acids and sugars in fruits and vegetables
10
ISO
210
507
Ret. time, tnin
2T0 ' [Temp. 'C 290 isorerm
Figure 1. Gas chromatogram of the TMS/TMS-oxime derivatives of 1 malic-, 2 citric-, 3 quinic acids, 4 fructose, 5 glucose, 6 sucrose. Column: 3 m x 4 mm stainless steel; filling: CHROMOSORB W AW DMCS 100-120 mesh, coated by 3% SE 30. Both injector and detector ports were 320°C; temperature programme: heated from 150 to 290°C at 12°C/min; held at 290°C for 4 min.
Ret.tin, .In. tix
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Figure 2. Gas chromatogram of the TMS/TMS-oxime derivatives of 1 glycolic-, 2 lactic-, 3 oxalic-, 4 sorbic-, 5 benzoic-, 6 succinic-, 7 malic-, 8 pimelic-, 9 tartaric acids, 10 arabinose, 11 xylose, 12 citric + isocitric acids, 13 rhamnose, 14 quinic acid, 15 mannitol, 16 sorbitol, 17 fructose, 18 ascorbic acid, 19 galactose, 20 mannose, 21 glucose, 22 palmitic-, 23 caffeic, 24 linoleic-, 25 stearic-, 26 arachidic-, 27 behenic acids, 28 sucrose, 29 maltose, 30 chlorogenic acid, 31 isomaltose, 32 raffinose, 33 maltotriose. Column: WCOT fused silica (10 m x 0-25 mm i.d.) (CHROMPACK). Both injector and detector ports were 300°C; temperature programme: hold at 60°C for 1 min, followed by 60 to 84°C at 12°C/min, then from 84 to 68°C at 14°C/min, hold at 168°C for 4 min, then from 168 to 270°C at 10°C/min, hold at 270°C for 12 min.
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Downloaded by [Purdue University] at 19:49 27 July 2013
(a) apple
isothra
25 Rat.tlm, "in. Isotherm 270 "C
lia
Figure 4. Gas chromatograms of the TMS/TMS-oxime derivatives obtained from fresh apple (a), pear (b) and grape (c). Peaks: 1 lactic-, 2 malic-, 3 pimelic-, 4 tartaric acids, 5 arabinose, 6 xylose, 7 citric + isocitric acids, 8 rhamnose, 9 quinic acid, 10 mannitol, 11 sorbitol, 12 fructose, 13 ascorbic acid, 14 galactose, 15 mannose, 16 glucose, 17 palmitic-, 18 caffeic-, 19 linoleic-, 20 arachidic acids, 21 sucrose, 22 maltose, 23 isomaltose, 24 chlorogenic acid and 25 rafnnose.
ti 1(8 Isotherm UB
zfa
Ret.tine, mm.
Isotherm
270 °C
Figure 5. Gas chromatograms of the TMS/TMS-oxime derivatives obtained from fresh orange (a), lemon (b), tomato (c) and banana (rf). Peaks: 1 succinic-, 2 malic-, 3 pimelic-, 4 tartaric acids, 5 xylose, 6 citric + isocitric-, 7 quinic acids, 8 sorbitol, 9 fructose, 10 ascorbic acid, 11 galactose, 12 mannose, 13 glucose, 14 palmitic acid, 15 sucrose, 16 maltose, 17 isomaltose, 18 rafnnose.
Detection of acids and sugars in fruits and vegetables -a
-o
11- .
(a) strawberry
21
Downloaded by [Purdue University] at 19:49 27 July 2013
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Figure 6. Gas chromatograms of the TMS/TMS-oxime derivatives obtained from: fresh strawberry (variety Aiko; gathered on 16.05.90 (a), carrot (b), cucumber (c) and potato (d). Peaks 1 lactic-, 2 succinic-, 3 malic-, 4 pimelic-, 5 tartaric acids, 6 arabinose, 7 xylose, 8 citric + isocitric-, 9 quinic acids, lOsorbitol, 11 fructose, 12 ascorbic acid, 13galactose, 14mannose, 15 glucose, 16 palmitic, 17 caffeic-, 18 linoleic- 19 stearic-, 20 arachidic acids, 21 sucrose, 22 maltose, 23 raffinose.
As can be seen, the number of identified components were 20-25, depending on the sample. The main differences in the composition of apple samples (samples 1-4) can be related to the place of preparation (sample 2, increased lactic acid and decreased rhamnose and sucrose contents), probably owing to the fact that in the factory the bacteria for lactic acid fermentation are immediately available. Smaller changes could be observed during the clarification procedure (sample 3, decreased oxalic and malic acid contents) and/or as a result of the concentration step (sample 4, decreased lactic acid, arabinose, fructose and glucose contents). Both reproducibility studies and tests concerning the amount and quality of the constituents present in different varieties of the matrices are in progress. References MOLNÁR-PERL, I., and PINTÉR-SZAKÁCS, M., 1981, Gas--liquid chromatographic separation and determination of the components of maltitol syrups. Journal of Chromatography, 216, 219-228. MOLNÁR-PERL, I., and PINTÉR-SZAKÁCS, M., 1984, Gas-liquid chromatographic determination of the raffinose family of oligosaccharides and their metabolites present in soya beans. Journal of Chromatography, 295, 443-433. MOLNÁR-PERL, I., and PINTÉR-SZAKÁCS, M., 1986, Monitoring of Maillard reaction in soy products. Zeitschrift für Lebensmittel-Unterschung und -Forschung, 183, 18-25. MOLNÁR-PERL, I., PINTÉR-SZAKÁCS, M., KÖVÁGÓ, Á., and PETRÖCZI, J., 1985, Quantitative extraction
and gas/liquid chromatography of the soluble saccharide in soya bean. Carbohydrate Research, 138, 83-89. MOLNÁR-PERL, I., MORVAI, M., PINTÉR-SZAKÁCS, M., KÖVÁGÓ, Á., and PETRÓCZI, J., 1990,
Gas--liquid chromatographic assay of the components of electrochemically reduced glucose solutions. Journal of Chromatography, 520, 185-191. MORVAI, M., and MOLNÁR-PERL, I., 1989, Simultaneous GLC quantitation of the characteristic organic acids and sugars in apples. Proceedings of the fifth European Conference on Food Chemistry,
514
/• Molndr-Perl and M. Morvai
Volume 2, Impact of Technology of Food Quality Food Chemistry and Quality Assurance, pp. 497-502. MORVAI, M., and MOLNÁR-PERL, I., 1990, Simultaneous determination of organic acids and sugars in apples by gas--liquid chromatography. Journal of Chromatography, 520, 201-207. MORVAI, M., PÁLYKA, I., and MOLNÁR-PERL, I., Flame ionization detector response factors using the effective carbon number concept in the quantitative analysis of esters. Journal of Chromatographic Science (in press). MORVAI, M., MOLNÁR-PERL,
I., and KNAUSZ, D., 1991, Simultaneous gas chromatographic
Downloaded by [Purdue University] at 19:49 27 July 2013
quantitation of sugars and acids as trimethylsilyl derivatives in vegetables and strawberries. Journal of Chromatography 552, 337-344.
Food Additives & Contaminants Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfac19
Rapid method for the simultaneous GC quantitation of acids and sugars in fruits and vegetables a
Ibolya Molnár‐Perl & Magdolna Morvai
a
a
Institute of Inorganic and Analytical Chemistry, L. Eötvös University, PO Box 32, Budapest 112, H‐1518, Hungary Published online: 10 Jan 2009.
To cite this article: Ibolya MolnrPerl & Magdolna Morvai (1992) Rapid method for the simultaneous GC quantitation of acids and sugars in fruits and vegetables, Food Additives & Contaminants, 9:5, 505-514, DOI: 10.1080/02652039209374104 To link to this article: http://dx.doi.org/10.1080/02652039209374104
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sublicensing, systematic supply, or distribution in any form to anyone is expressly
Downloaded by [Purdue University] at 19:49 27 July 2013
forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
FOOD ADDITIVES AND CONTAMINANTS, 1992, VOL. 9, NO. 5, 505-514
Rapid method for the simultaneous GC quantitation of acids and sugars in fruits and vegetables IBOLYA MOLNÁR-PERL and MAGDOLNA MORVAI
Downloaded by [Purdue University] at 19:49 27 July 2013
Institute of Inorganic and Analytical Chemistry, L. Eötvös University, Budapest 112, PO Box 32, H-1518, Hungary Rapid methods of analysis for the simultaneous determination of acids and sugars in fruits and vegetables using trimethylsilylation and gas chromatography are reported. The methods have been shown to be generally applicable, rapid, simple and cheap. Typical applications are shown involving the determination of a range of organic acids and sugars in carrot, potato, cucumber, tomato, apple, pear, grape, strawberry and citrus fruits. Keywords: simultaneous analysis of acids and sugars, gas chromatography, trimethylsilyl derivatives, carrot, potato, cucumber, tomato, apple, pear, grape, strawberry, citrus fruits
Introduction
The goal of this compilation is to propagate the use of the trimethylsilylether/ester(TMS) and TMS-oxime derivatives in the qualitative and quantitative analysis of acids and sugars by gas chromatography(GC), of those acids and sugars which are present in almost all plants, fruits, vegetables, foods and food products as their main constituents. As to the relevancy of the topic, it is known how important can be the exact knowledge of the qualitative and quantitative distribution of the characteristic acids and sugars in various matrices. Namely, both their absolute amounts and/or the ratios of their amounts (i) can serve as a powerful tool to detect adulteration and/or presevatives in juices, ciders or in other fruit products, (ii) are indices to control the changes in the production and in the storage of fresh, frozen or canned products, and, (iii) are indicators in the evaluation of fruit maturity. The reason for the importance of this derivatization technique can be explained as follows: (a) the general applicability of the silylation technique to all compounds containing active hydrogen functions (—OH, —COOH, - S H , — NH2, —NH, —POH, -SOH); (b) the relatively slightly increased molecular weight of derivatized products compared to underivatized ones, a very important feature of this technique from the point of view of the higher molecular weight components, such as sugars with a degree of polymerization up to 5; (c) the simplicity (it is a rapid procedure, neither time consuming nor tedious); and, (d) the low cost of the method. 0265-203X/92 $3.00 © 1992 Taylor & Francis Ltd.
506
/. Molndr-Perl and M. Morvai
As can be seen, the examples (point (a)) cover almost all the main functional groups of organics which can be converted to the corresponding silyl derivatives (with the sole exception of the carbonyl group which has to be oximated prior to silylation). Finally, in connection with the general applicability of the silylation technique, one disadvantage of this derivatization procedure is to be emphasized: in order to get quantitative interactions, the optimum silylation parameters, which are considerably different for the various groups of organics, have to be followed strictly.
Downloaded by [Purdue University] at 19:49 27 July 2013
Materials and methods The materials and methods used are detailed elsewhere (Molnar-Perl and Pinter-Szakacs 1981, 1984, 1986, Molnar-Perl et al. 1985, 1990, Morvai and Molnar-Perl 1989, 1990, Morvai et al. 1991, Morvai et al. in press). Results
Taking into account the limitations detailed above and lack of literature data, there was a need for a really appropriate method for the analysis of sugars and acids, simultaneously, potentially present in matrices of interest. Thus, an exhaustive study was done (as a function of the composition and the quality of the silylating agent, time and temperature of interactions), in order to optimize the quantitative and competitive protocol with respect to both the silylation and GC conditions, and for all compounds listed (in tables 1-3 and/or in figures 1-6). As a result of our efforts we have added two new principles to this field: (a) the development of silylation and GC procedures, satisfactory for numerous compounds potentially present in matrices of interest, ensuring (i) quantitative silylation without any side reaction, (ii) within a reasonable reaction time (20 min) and temperature (125°C), and (iii) with a good reproducibility of the measurements; (b) the possibility of the quantification of compounds being present in extremely different concentration ranges (10~3-10% w/w) based on the discovery that the silylated solutions of acids and sugars can be evaporated, without any irreversible changes. (without going into details of previously published analytical aspects) are shown some concrete tasks, solved without exception with the GC analysis of silyl derivatives. As has been detailed in the introductory part of this compilation the unified procedure appropriate for the simultaneous measurement of numerous acids and sugars as TMS and/or TMS-oxime derivatives, from a single solution by one injection was developed. According to the task and the equipment and materials available, we optimized two programmes: the short programme (figure 1) can be suggested for the measurement of the main components and also for analysts having older apparatus and packed columns only. The long programme (figure 2, table 1) developed on a Chrompack CP 9000 apparatus using a fused silica capillary column of 10 m length can be recommended for special tasks needing also a knowledge of the amounts of trace constituents.
Downloaded by [Purdue University] at 19:49 27 July 2013
Detection of acids and sugars in fruits and vegetables
10
ISO
210
507
Ret. time, tnin
2T0 ' [Temp. 'C 290 isorerm
Figure 1. Gas chromatogram of the TMS/TMS-oxime derivatives of 1 malic-, 2 citric-, 3 quinic acids, 4 fructose, 5 glucose, 6 sucrose. Column: 3 m x 4 mm stainless steel; filling: CHROMOSORB W AW DMCS 100-120 mesh, coated by 3% SE 30. Both injector and detector ports were 320°C; temperature programme: heated from 150 to 290°C at 12°C/min; held at 290°C for 4 min.
Ret.tin, .In. tix
lsottera
lit
zh
Figure 2. Gas chromatogram of the TMS/TMS-oxime derivatives of 1 glycolic-, 2 lactic-, 3 oxalic-, 4 sorbic-, 5 benzoic-, 6 succinic-, 7 malic-, 8 pimelic-, 9 tartaric acids, 10 arabinose, 11 xylose, 12 citric + isocitric acids, 13 rhamnose, 14 quinic acid, 15 mannitol, 16 sorbitol, 17 fructose, 18 ascorbic acid, 19 galactose, 20 mannose, 21 glucose, 22 palmitic-, 23 caffeic, 24 linoleic-, 25 stearic-, 26 arachidic-, 27 behenic acids, 28 sucrose, 29 maltose, 30 chlorogenic acid, 31 isomaltose, 32 raffinose, 33 maltotriose. Column: WCOT fused silica (10 m x 0-25 mm i.d.) (CHROMPACK). Both injector and detector ports were 300°C; temperature programme: hold at 60°C for 1 min, followed by 60 to 84°C at 12°C/min, then from 84 to 68°C at 14°C/min, hold at 168°C for 4 min, then from 168 to 270°C at 10°C/min, hold at 270°C for 12 min.
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Table 3. Su,gar aiid orgi
51]
512
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Downloaded by [Purdue University] at 19:49 27 July 2013
(a) apple
isothra
25 Rat.tlm, "in. Isotherm 270 "C
lia
Figure 4. Gas chromatograms of the TMS/TMS-oxime derivatives obtained from fresh apple (a), pear (b) and grape (c). Peaks: 1 lactic-, 2 malic-, 3 pimelic-, 4 tartaric acids, 5 arabinose, 6 xylose, 7 citric + isocitric acids, 8 rhamnose, 9 quinic acid, 10 mannitol, 11 sorbitol, 12 fructose, 13 ascorbic acid, 14 galactose, 15 mannose, 16 glucose, 17 palmitic-, 18 caffeic-, 19 linoleic-, 20 arachidic acids, 21 sucrose, 22 maltose, 23 isomaltose, 24 chlorogenic acid and 25 rafnnose.
ti 1(8 Isotherm UB
zfa
Ret.tine, mm.
Isotherm
270 °C
Figure 5. Gas chromatograms of the TMS/TMS-oxime derivatives obtained from fresh orange (a), lemon (b), tomato (c) and banana (rf). Peaks: 1 succinic-, 2 malic-, 3 pimelic-, 4 tartaric acids, 5 xylose, 6 citric + isocitric-, 7 quinic acids, 8 sorbitol, 9 fructose, 10 ascorbic acid, 11 galactose, 12 mannose, 13 glucose, 14 palmitic acid, 15 sucrose, 16 maltose, 17 isomaltose, 18 rafnnose.
Detection of acids and sugars in fruits and vegetables -a
-o
11- .
(a) strawberry
21
Downloaded by [Purdue University] at 19:49 27 July 2013
11
20
LJuJS
JJJLLJ
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» 1(8
513
Isotherm UB
Ret.tin, ain. 270
Figure 6. Gas chromatograms of the TMS/TMS-oxime derivatives obtained from: fresh strawberry (variety Aiko; gathered on 16.05.90 (a), carrot (b), cucumber (c) and potato (d). Peaks 1 lactic-, 2 succinic-, 3 malic-, 4 pimelic-, 5 tartaric acids, 6 arabinose, 7 xylose, 8 citric + isocitric-, 9 quinic acids, lOsorbitol, 11 fructose, 12 ascorbic acid, 13galactose, 14mannose, 15 glucose, 16 palmitic, 17 caffeic-, 18 linoleic- 19 stearic-, 20 arachidic acids, 21 sucrose, 22 maltose, 23 raffinose.
As can be seen, the number of identified components were 20-25, depending on the sample. The main differences in the composition of apple samples (samples 1-4) can be related to the place of preparation (sample 2, increased lactic acid and decreased rhamnose and sucrose contents), probably owing to the fact that in the factory the bacteria for lactic acid fermentation are immediately available. Smaller changes could be observed during the clarification procedure (sample 3, decreased oxalic and malic acid contents) and/or as a result of the concentration step (sample 4, decreased lactic acid, arabinose, fructose and glucose contents). Both reproducibility studies and tests concerning the amount and quality of the constituents present in different varieties of the matrices are in progress. References MOLNÁR-PERL, I., and PINTÉR-SZAKÁCS, M., 1981, Gas--liquid chromatographic separation and determination of the components of maltitol syrups. Journal of Chromatography, 216, 219-228. MOLNÁR-PERL, I., and PINTÉR-SZAKÁCS, M., 1984, Gas-liquid chromatographic determination of the raffinose family of oligosaccharides and their metabolites present in soya beans. Journal of Chromatography, 295, 443-433. MOLNÁR-PERL, I., and PINTÉR-SZAKÁCS, M., 1986, Monitoring of Maillard reaction in soy products. Zeitschrift für Lebensmittel-Unterschung und -Forschung, 183, 18-25. MOLNÁR-PERL, I., PINTÉR-SZAKÁCS, M., KÖVÁGÓ, Á., and PETRÖCZI, J., 1985, Quantitative extraction
and gas/liquid chromatography of the soluble saccharide in soya bean. Carbohydrate Research, 138, 83-89. MOLNÁR-PERL, I., MORVAI, M., PINTÉR-SZAKÁCS, M., KÖVÁGÓ, Á., and PETRÓCZI, J., 1990,
Gas--liquid chromatographic assay of the components of electrochemically reduced glucose solutions. Journal of Chromatography, 520, 185-191. MORVAI, M., and MOLNÁR-PERL, I., 1989, Simultaneous GLC quantitation of the characteristic organic acids and sugars in apples. Proceedings of the fifth European Conference on Food Chemistry,
514
/• Molndr-Perl and M. Morvai
Volume 2, Impact of Technology of Food Quality Food Chemistry and Quality Assurance, pp. 497-502. MORVAI, M., and MOLNÁR-PERL, I., 1990, Simultaneous determination of organic acids and sugars in apples by gas--liquid chromatography. Journal of Chromatography, 520, 201-207. MORVAI, M., PÁLYKA, I., and MOLNÁR-PERL, I., Flame ionization detector response factors using the effective carbon number concept in the quantitative analysis of esters. Journal of Chromatographic Science (in press). MORVAI, M., MOLNÁR-PERL,
I., and KNAUSZ, D., 1991, Simultaneous gas chromatographic
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quantitation of sugars and acids as trimethylsilyl derivatives in vegetables and strawberries. Journal of Chromatography 552, 337-344.
