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Reduction of the glucose syrup browning rate by the use of modified atmosphere packaging
Journal of Food Engineering 80 (2007) 370–373 www.elsevier.com/locate/jfoodeng
Reduction of the glucose syrup browning rate by the use of modified atmosphere packaging Ahmadreza Raisi a, Abdolreza Aroujalian a
a,b,*
Department of Chemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave., P.O.Box 15875-4413, Tehran, Iran b Food Processing Engineering and Biotechnology Research Center, Amirkabir University of Technology (Tehran Polytechnic), Hafez St., P.O.BOX 15875-4413, Tehran, Iran Received 13 June 2004; received in revised form 19 April 2006; accepted 20 April 2006 Available online 1 August 2006
Abstract Effects of modified atmosphere packaging (MAP) on browning in glucose syrups stored at 25 °C and 45 °C were studied. Different atmosphere such as air, 100% N2, 90% N2/10% O2, 25% CO2/75% N2, 75% CO2/25% N2 and vacuum were examined. The glucose syrups stored at 45 °C and pH 5 were completely brown after 26 weeks under vacuum packaging while they were brown after 15 weeks at that temperature and pH 6 under air packaging system. No color formation was observed in glucose syrups stored at 25 °C during this work. As so glucose syrups kept under CO2 gas had no significant effect on browning. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Glucose syrups; Browning; Modified atmosphere packaging (MAP); Shelf life
1. Introduction Shelf life is the duration of that period between the packaging of a product and its use, for which the quality of the product remains acceptable to the product user or the shelf life refers to the time for which a food can remain on both the retailer’s and consumer’s shelf before it becomes unacceptable (Robertson, 1993). Product shelf life can be controlled by three factors: (i) product characteristics, (ii) the environment to which the product is exposed during distribution, and (iii) the properties of the package. The shelf life of a product can be altered by changing its composition and form, the environment to which it is exposed, or the packaging system (Harte & Gray, 1987). In the case of glucose syrup, the major factor affecting the shelf life is brown color formation. Maillard reactions are the main causes of brown color formation in glucose syrup. Non-enzymatic browning reactions between amino acids *
Corresponding author. Tel.: +98 21 64543163; fax: +98 21 66405847. E-mail address: [email protected] (A. Aroujalian).
0260-8774/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2006.04.061
and reducing sugars are the basis of the Maillard reactions. This reaction in food is actually a complex network of chemical reactions which usually takes place during food processing or storage. Maillard reactions play an essential role in food acceptance through the ways they influence quality factors such as flavor, color, texture and nutritional value (Rizzi, 1994). In glucose syrups, the formation of color and odors determines the sensorial properties such as taste and flavor and also provides an index of purity. Color formation in glucose syrups during the manufacture of high boiled candies can be serious problems for the confectionery industry as it may lead to the loss of acceptable color and to the development of off-flavors (Kearsley & Brich, 1985). Mechanism and kinetic of color formation and factors affecting color development in glucose syrups during storage such as time of storage, temperature, pH, dextrose equivalent and sulfur dioxide, have been previously studied (Ramchander & Feather, 1975; Kearsley, 1978; Sapers, 1993; Bostan & Boyacioglu, 1997). In this work, effects modified atmosphere packaging (MAP) on the color formation and shelf lives of glucose syrups were determined.
A. Raisi, A. Aroujalian / Journal of Food Engineering 80 (2007) 370–373
a air
90% N2 /10% O2
100% N2
vacuum
1.0 0.8
Absorbance
Glucose syrup with 42 DE, 82.5° Brix and pH 4.78 were donated by Glucosan Co., Tehran, Iran. The used glucose syrups were produced from acid hydrolysis of corn starch. The physical and chemical characteristics of this syrup present in Table 1. Chloride acid and sodium hydroxide (Merck grade) were used for pH adjustment. The pH was measured with a Jenewy pH-meter which was calibrated according to the method of the Corn Refiners Association CRA (1985). The soluble solids were measured in degree of Brix with an Abbe refractometer at 25 °C. The Brix data were related to the total solids content of the syrup using the Critical Data Tables prepared for syrups with know DE values. Color indices of the syrups were measured by their absorbance at 295 nm on Perkin–Elemer model 550 UV/ VIS double beams spectrophotometer using a 1 cm path length cell. The wavelength used was based on the wavelength maximum obtained from spectral scans of aged syrup (Meydav, Saguy, & Kopelman, 1977). The protein contents of glucose syrup samples were determined by Kjeltec Auto 1030 Analyzer according to the method of ISI (1999). The carbohydrate profiles were determined by Jasco High Pressure Liquid Chromatography (HPLC) instrument using a carbohydrate analysis column and RI detector. The solvent system was a mixture of acetonitryle and deionized water (80/20) and the flow rate was 2 ml/min. For preparation of samples, at first pH of syrup was adjust to 4, 5 and 6 with the addition of 0.1 N NaOH and 0.1 N HCl, then they were put into polyethylene/aluminum/polyester pouch then packed with Henkelman 200A vacuum machine under six different atmospheric condition of air, 100% N2, 90% N2/10% O2, 25% CO2/75% N2, 75% CO2/25% N2 and vacuum. Finally samples were stored in thermostatic ovens of 25 and 45 °C.
cose syrup samples to reach the later value. Browning rate of syrups under four atmospheric condition of air, 100% N2, 90% N2/10% O2 and vacuum at pH 4 and temperature of 25 °C and 45 °C are shown in Figs. 1a and 2a, respectively. As shown in these figures, the browning rate in syrups stored at 45 °C was higher than those stored at 25 °C. Another result can be mentioned from these figures, browning rate in all syrups increased when oxygen content in package increased. Browning rate in syrups which stored under air condition was maximal, and also it was higher under 90% N2/10% O2 than 100% N2. These observations showed that oxygen can be accelerated non-enzymatic browning. The accelerate effect of oxygen on the rate of browning may be attributed to the fact that oxygen is required for formation of some interme-
0.6 0.4 0.2 0.0 2
0
4
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2. Materials and methods
371
3. Results and discussion
0.6 0.4 0.2
Table 1 Chemical and physical characteristics of glucose syrups Characteristics
Amount
DE PH Soluble solids Glucose Maltose Protein
42 4.78 82.5% 24.38% 13.87% 0.03–0.05%
0.0 0
2
4
6
8
10
12
14
16
Time (week)
c
1 0.8
Absorbance
Browning rate was measured as changes in absorbance values of glucose syrup samples at 295 nm as a function of time. Each package was opened and tested at two week interval times during storage of the samples in thermostatic oven at 25 °C and 45 °C. At absorbance value of 0.9 syrups had a light yellow color while at absorbance value of 3.72 syrup color was completely brown. Thus, the shelf life was defined as the time taken for the absorbance of stored glu-
0.6 0.4 0.2 0 0
2
4
6
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28
Time (week)
Fig. 1. Influence of packaging atmosphere on color formation in glucose syrups stored at 25 °C: (a) pH 4, (b) pH 5 and (c) pH 6.
A. Raisi, A. Aroujalian / Journal of Food Engineering 80 (2007) 370–373
a air
90% N2 /10% O2
100% N2
vacuum
4.5 4.0
Absorbance
3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0
2
4
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3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0
2
4
6
8
10
12
Time (week)
c
5.0 4.5
Absorbance
4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0
2
4
6
8
10
12
20
22
Time (week)
Fig. 2. Influence of packaging atmosphere on color formation in glucose syrups stored at 45 °C: (a) pH 4, (b) pH 5 and (c) pH 6.
diates in Maillard reactions and it can also alter the pathways of Maillard reactions. Although no data are reported on the influence of oxygen on the Maillard reactions in glucose syrup, some authors have studied the effects of oxygen on this reaction. Rada-Mendoza, Villamiel, and Olano (2002) demonstrated that the dissolved oxygen has a significant effect on the formation of Amadori compounds during the heat treatment of milk. Hayase, Shibuya, Sato, and Yamamoto (1996) observed less browning under aerobic conditions. Yeboah, Alli, and Yaylayan (1999) and Yeboah, Alli, Yaylayan, Konishi, and Stefanowicz (2000), studying the glycation of proteins via the Maillard reaction, demonstrated that the presence of oxygen in the reaction system induces oxi-
dative side reactions, which can slow the initial rate of formation of Amadori compounds. Studies of browning in simulated bread crust have revealed that oxygen is required for Maillard reactions since baking in a vacuum oven caused less damage (Ziderman & Friedman, 1985). Oxidative conditions enhance the browning of proteins by glucose (Knecht, Lyons, Thorpe, & Baynes, 1992; Knecht et al., 1994). Oxygen is a potent catalyst of the Maillard reactions between glucose and protein at physiological pH and temperature in vitro, leading to formation of characteristic glycoxidation products, such as Ne-(carboxymethyl) lysine (CML) and pentosidine. The browning of protein by glucose was accelerated approximately 2-folds under oxidative, compared to antioxidative conditions (Litchfield, Thorpe, & Baynes, 1999). As shown in Figs. 1a and 2a, browning rate in glucose syrups stored under vacuum is lower compared to samples stored in 100% N2. Both samples had no oxygen content and they just were kept under different hydrostatic pressure, thus it can be resulted that browning reaction has been influenced by storage pressure. Browning reaction was significantly suppressed by the pressure at 50–200 MPa with the activation volume of 13–27 ml/mol (Toru, Noriichi, & Rikimaru, 1991). Also it has been shown that high hydrostatic pressure affected the formation of intense chromophores formed from pentoses and primary amino acids (Frank, Heberle, Schieberle, & Hofmanu, 2000) and the formation of volatile components of a glucose/lysine model system (Hill, Isaacs, Ledward, & Ames, 1999). The effect of pressure on Maillard reaction may be attributed to this fact that the first stage, formation of the Amadori rearrangement product, is accelerated by pressure while the second stage, its degradation, is retarded. The Amadori rearrangement product is formed rapidly but decomposes more slowly under high pressure conditions (Bristow & Isaacs, 1999). Also Figs. 1 and 2 show browning rate in glucose syrups with pH 5 and 6 stored at 25 °C (Fig. 1b and c) and 45 °C. As shown in these figures, the results obtained from browning T= 25°C, 25% CO2
T= 25°C, 75% CO2
T= 45°C, 25% CO2
T= 45°C, 25% CO2
3.5 3.0
Absorbance
372
2.5 2.0 1.5 1.0 0.5 0.0 0
2
4
6
8
10
12
14
16
18
20
Time (week)
Fig. 3. Influence of CO2 on color formation in glucose syrups with pH 5 stored at 25 °C and 45 °C.
A. Raisi, A. Aroujalian / Journal of Food Engineering 80 (2007) 370–373 Table 2 Shelf lives for glucose syrups stored at 45 °C under various storage conditions pH 4
pH 5
pH 6
Air
Time (week) to abs. = 3.72 Time (week) to abs. = 0.9
16.6 1.5
19.5 2.1
15.0 1.3
90% N2/10% O2
Time (week) to abs. = 3.72 Time (week) to abs. = 0.9
18.1 2.4
20.9 2.8
16.6 2.1
100% N2
Time (week) to abs. = 3.72 Time (week) to abs. = 0.9
19.6 3.0
22.6 3.5
18.0 2.9
Vacuum
Time (week) to abs. = 3.72 Time (week) to abs. = 0.9
21.8 3.6
26.1 4.5
20.3 3.5
rate of syrup with pH 4 were similar to other pH values. Also browning rate for syrups stored under CO2 were similar to all syrups stored under 100% N2, results shown in Fig. 3. Shelf lives for glucose syrups with pH 5 stored at 45 °C under air, 90% N2/10% O2, 100% N2 and vacuum condition were 16.6, 18.1, 19.6 and 21.8 weeks, respectively while no color formation was observed in glucose syrups stored at 25 °C under these storage conditions. Shelf lives values for all syrups under above conditions are presented in Table 2. 4. Conclusion Maillard reactions are the main causes of brown color formation in glucose syrup. Oxygen and pressure were affected the Maillard reaction. In the absence of oxygen, browning rate in glucose syrup samples was low while it enhanced with increase in oxygen content. Under vacuum pressure, browning rate was very low while it increased under atmospheric pressure. The longest shelf lives of stored glucose syrups were about 26 weeks at pH 5 and the shortest shelf lives were 15 weeks at pH 6 for syrups stored at 45 °C, respectively. For syrups stored at 25 °C, no color formation was observed. This study shows modified atmospheric packaging (MAP) is a useful system to enhance the shelf lives of the glucose syrups. Acknowledgements The authors would like to thank Glucosan Co. (Tehran, Iran) for supplying glucose syrup. References Bostan, A., & Boyacioglu, D. (1997). Kinetics of non-enzymatic color development in glucose syrups during storage. Food Chemistry, 60(4), 581–585. Bristow, M., & Isaacs, N. S. (1999). The effect of high hydrostatic pressure on the volatile products in a model Maillard reaction. Journal of Chemical Society, Perkin Transactions 2, 2213–2218.
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CRA (1985). E48 PH measurement method. Washington, DC: Corn Refiners Association Inc. Frank, O., Heberle, I., Schieberle, P., & Hofmanu, Th. (2000). Influence of high hydrostatic pressure on the formation of intense chromophores formed from pentoses and primary amino acids. International Congress Series, 1245(November), 387–388. Harte, B. R., & Gray, J. I. (1987). The influence of packaging on product quality. In J. I. Gray, B. R. Harte, & J. Miltz (Eds.), Food productpackage compatibility proceedings (pp. 17). Lancaster, Pennsylvania: Technomic Publishing Co. Inc. Hayase, F., Shibuya, T., Sato, J., & Yamamoto, M. (1996). Effects of oxygen and transition metals on the advanced Maillard reaction of proteins with glucose. Bioscience, Biotechnology & Biochemistry, 60, 1820–1825. Hill, V. M., Isaacs, N. S., Ledward, D. A., & Ames, J. M. (1999). Effect of high hydrostatic pressure on the volatile components of a glucose– lysine model system. Journal of Agricultural and Food Chemistry, 47(9), 3675–3681. ISI (1999). ISI 24-1e Determination of Protein by Kjeldah. Science Park Aarhus, Denmark: International Starch Institute. Kearsley, M. W. (1978). The control of hygroscopicity, browning and fermentation in glucose syrups. Journal of Food Technology, 13, 339–348. Kearsley, M. W., & Brich, G. G. (1985). The chemistry and metabolism of the starch based sweeteners. Food Chemistry, 16, 191–207. Knecht, K. J., Lyons, T. J., Thorpe, S. R., & Baynes, J. W. (1992). Role of oxygen in the crosslinking and chemical modification of protein by glucose. Diabetes, 41(2), 42–48. Knecht, K. J., Lyons, T. J., Fu, M. X., Blackledge, J. A., Thorpe, S. R., & Baynes, J. W. (1994). Glycation, glycoxidation and crosslinking of collagen by glucose; kinetics, mechanisms and inhibition of late stages of Maillard reaction. Diabetes, 43, 676–683. Litchfield, J. E., Thorpe, S. R., & Baynes, J. W. (1999). Oxygen is not required for browning and crosslinking of protein by pentoses: relevance to Maillard reactions in vivo. International Journal Biochemistry and Cell Biology, 31(11), 1297–1305. Meydav, S., Saguy, I., & Kopelman, J. I. (1977). Browning determination in citrus products. Journal of Agricultural and Food Chemistry, 25(3), 602–604. Rada-Mendoza, M., Villamiel, M., & Olano, A. (2002). Dissolved air effects on lactose isomerisation and furosine formation during heat treatment of milk. Lait, 82(5), 629–634. Ramchander, S., & Feather, M. S. (1975). Studies on the mechanism of color formation in Glucose Syrups. Cereal Chemistry, 52, 167–173. Rizzi, G. P. (1994). The Maillard reaction in foods. Maillard reactions. In T. P. Labuza, G. A. Reineccius, V. M. Monnier, J. O’Brien, & J. W. Baynes (Eds.), Chemistry, food and health (pp. 11). The Royal Society of Chemistry. Robertson, G. L. (1993). Shelf life of foods. In H. Huges (Ed.), Food packaging: principles and practice (pp. 339). NewYork: Marcel Dekker. Sapers, G. M. (1993). Browning of foods: control by sulfites, antioxidants and other means. Food Technology, 47(10), 75–84. Toru, T., Noriichi, I., & Rikimaru, H. (1991). High pressure effect on Maillard reaction. Agricultural and Biology Chemistry, 55(8), 2071–2074. Yeboah, F. K., Alli, I., & Yaylayan, V. A. (1999). Reactivities of D-glucose and D-fructose during glycation of bovine serum albumin. Journal Agricultural Food Chemistry, 47, 3164–3172. Yeboah, F. K., Alli, I., Yaylayan, V. A., Konishi, Y., & Stefanowicz, P. (2000). Monitoring glycation of lysozyme by electrospray ionization mass spectrometry. Journal Agricultural Food Chemistry, 48, 2766–2774. Ziderman, I. I., & Friedman, M. (1985). Thermal and compositional changes of dry wheat gluten-carbohydrate mixtures during simulated crust baking. Journal of Agricultural and Food Chemistry, 33, 1096–1102.
Reduction of the glucose syrup browning rate by the use of modified atmosphere packaging Ahmadreza Raisi a, Abdolreza Aroujalian a
a,b,*
Department of Chemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave., P.O.Box 15875-4413, Tehran, Iran b Food Processing Engineering and Biotechnology Research Center, Amirkabir University of Technology (Tehran Polytechnic), Hafez St., P.O.BOX 15875-4413, Tehran, Iran Received 13 June 2004; received in revised form 19 April 2006; accepted 20 April 2006 Available online 1 August 2006
Abstract Effects of modified atmosphere packaging (MAP) on browning in glucose syrups stored at 25 °C and 45 °C were studied. Different atmosphere such as air, 100% N2, 90% N2/10% O2, 25% CO2/75% N2, 75% CO2/25% N2 and vacuum were examined. The glucose syrups stored at 45 °C and pH 5 were completely brown after 26 weeks under vacuum packaging while they were brown after 15 weeks at that temperature and pH 6 under air packaging system. No color formation was observed in glucose syrups stored at 25 °C during this work. As so glucose syrups kept under CO2 gas had no significant effect on browning. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Glucose syrups; Browning; Modified atmosphere packaging (MAP); Shelf life
1. Introduction Shelf life is the duration of that period between the packaging of a product and its use, for which the quality of the product remains acceptable to the product user or the shelf life refers to the time for which a food can remain on both the retailer’s and consumer’s shelf before it becomes unacceptable (Robertson, 1993). Product shelf life can be controlled by three factors: (i) product characteristics, (ii) the environment to which the product is exposed during distribution, and (iii) the properties of the package. The shelf life of a product can be altered by changing its composition and form, the environment to which it is exposed, or the packaging system (Harte & Gray, 1987). In the case of glucose syrup, the major factor affecting the shelf life is brown color formation. Maillard reactions are the main causes of brown color formation in glucose syrup. Non-enzymatic browning reactions between amino acids *
Corresponding author. Tel.: +98 21 64543163; fax: +98 21 66405847. E-mail address: [email protected] (A. Aroujalian).
0260-8774/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2006.04.061
and reducing sugars are the basis of the Maillard reactions. This reaction in food is actually a complex network of chemical reactions which usually takes place during food processing or storage. Maillard reactions play an essential role in food acceptance through the ways they influence quality factors such as flavor, color, texture and nutritional value (Rizzi, 1994). In glucose syrups, the formation of color and odors determines the sensorial properties such as taste and flavor and also provides an index of purity. Color formation in glucose syrups during the manufacture of high boiled candies can be serious problems for the confectionery industry as it may lead to the loss of acceptable color and to the development of off-flavors (Kearsley & Brich, 1985). Mechanism and kinetic of color formation and factors affecting color development in glucose syrups during storage such as time of storage, temperature, pH, dextrose equivalent and sulfur dioxide, have been previously studied (Ramchander & Feather, 1975; Kearsley, 1978; Sapers, 1993; Bostan & Boyacioglu, 1997). In this work, effects modified atmosphere packaging (MAP) on the color formation and shelf lives of glucose syrups were determined.
A. Raisi, A. Aroujalian / Journal of Food Engineering 80 (2007) 370–373
a air
90% N2 /10% O2
100% N2
vacuum
1.0 0.8
Absorbance
Glucose syrup with 42 DE, 82.5° Brix and pH 4.78 were donated by Glucosan Co., Tehran, Iran. The used glucose syrups were produced from acid hydrolysis of corn starch. The physical and chemical characteristics of this syrup present in Table 1. Chloride acid and sodium hydroxide (Merck grade) were used for pH adjustment. The pH was measured with a Jenewy pH-meter which was calibrated according to the method of the Corn Refiners Association CRA (1985). The soluble solids were measured in degree of Brix with an Abbe refractometer at 25 °C. The Brix data were related to the total solids content of the syrup using the Critical Data Tables prepared for syrups with know DE values. Color indices of the syrups were measured by their absorbance at 295 nm on Perkin–Elemer model 550 UV/ VIS double beams spectrophotometer using a 1 cm path length cell. The wavelength used was based on the wavelength maximum obtained from spectral scans of aged syrup (Meydav, Saguy, & Kopelman, 1977). The protein contents of glucose syrup samples were determined by Kjeltec Auto 1030 Analyzer according to the method of ISI (1999). The carbohydrate profiles were determined by Jasco High Pressure Liquid Chromatography (HPLC) instrument using a carbohydrate analysis column and RI detector. The solvent system was a mixture of acetonitryle and deionized water (80/20) and the flow rate was 2 ml/min. For preparation of samples, at first pH of syrup was adjust to 4, 5 and 6 with the addition of 0.1 N NaOH and 0.1 N HCl, then they were put into polyethylene/aluminum/polyester pouch then packed with Henkelman 200A vacuum machine under six different atmospheric condition of air, 100% N2, 90% N2/10% O2, 25% CO2/75% N2, 75% CO2/25% N2 and vacuum. Finally samples were stored in thermostatic ovens of 25 and 45 °C.
cose syrup samples to reach the later value. Browning rate of syrups under four atmospheric condition of air, 100% N2, 90% N2/10% O2 and vacuum at pH 4 and temperature of 25 °C and 45 °C are shown in Figs. 1a and 2a, respectively. As shown in these figures, the browning rate in syrups stored at 45 °C was higher than those stored at 25 °C. Another result can be mentioned from these figures, browning rate in all syrups increased when oxygen content in package increased. Browning rate in syrups which stored under air condition was maximal, and also it was higher under 90% N2/10% O2 than 100% N2. These observations showed that oxygen can be accelerated non-enzymatic browning. The accelerate effect of oxygen on the rate of browning may be attributed to the fact that oxygen is required for formation of some interme-
0.6 0.4 0.2 0.0 2
0
4
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b
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Absorbance
2. Materials and methods
371
3. Results and discussion
0.6 0.4 0.2
Table 1 Chemical and physical characteristics of glucose syrups Characteristics
Amount
DE PH Soluble solids Glucose Maltose Protein
42 4.78 82.5% 24.38% 13.87% 0.03–0.05%
0.0 0
2
4
6
8
10
12
14
16
Time (week)
c
1 0.8
Absorbance
Browning rate was measured as changes in absorbance values of glucose syrup samples at 295 nm as a function of time. Each package was opened and tested at two week interval times during storage of the samples in thermostatic oven at 25 °C and 45 °C. At absorbance value of 0.9 syrups had a light yellow color while at absorbance value of 3.72 syrup color was completely brown. Thus, the shelf life was defined as the time taken for the absorbance of stored glu-
0.6 0.4 0.2 0 0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
Time (week)
Fig. 1. Influence of packaging atmosphere on color formation in glucose syrups stored at 25 °C: (a) pH 4, (b) pH 5 and (c) pH 6.
A. Raisi, A. Aroujalian / Journal of Food Engineering 80 (2007) 370–373
a air
90% N2 /10% O2
100% N2
vacuum
4.5 4.0
Absorbance
3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0
2
4
6
8
10
12
14
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20
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14
16
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22
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18
Time (week)
b
4.5 4.0
Absorbance
3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0
2
4
6
8
10
12
Time (week)
c
5.0 4.5
Absorbance
4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0
2
4
6
8
10
12
20
22
Time (week)
Fig. 2. Influence of packaging atmosphere on color formation in glucose syrups stored at 45 °C: (a) pH 4, (b) pH 5 and (c) pH 6.
diates in Maillard reactions and it can also alter the pathways of Maillard reactions. Although no data are reported on the influence of oxygen on the Maillard reactions in glucose syrup, some authors have studied the effects of oxygen on this reaction. Rada-Mendoza, Villamiel, and Olano (2002) demonstrated that the dissolved oxygen has a significant effect on the formation of Amadori compounds during the heat treatment of milk. Hayase, Shibuya, Sato, and Yamamoto (1996) observed less browning under aerobic conditions. Yeboah, Alli, and Yaylayan (1999) and Yeboah, Alli, Yaylayan, Konishi, and Stefanowicz (2000), studying the glycation of proteins via the Maillard reaction, demonstrated that the presence of oxygen in the reaction system induces oxi-
dative side reactions, which can slow the initial rate of formation of Amadori compounds. Studies of browning in simulated bread crust have revealed that oxygen is required for Maillard reactions since baking in a vacuum oven caused less damage (Ziderman & Friedman, 1985). Oxidative conditions enhance the browning of proteins by glucose (Knecht, Lyons, Thorpe, & Baynes, 1992; Knecht et al., 1994). Oxygen is a potent catalyst of the Maillard reactions between glucose and protein at physiological pH and temperature in vitro, leading to formation of characteristic glycoxidation products, such as Ne-(carboxymethyl) lysine (CML) and pentosidine. The browning of protein by glucose was accelerated approximately 2-folds under oxidative, compared to antioxidative conditions (Litchfield, Thorpe, & Baynes, 1999). As shown in Figs. 1a and 2a, browning rate in glucose syrups stored under vacuum is lower compared to samples stored in 100% N2. Both samples had no oxygen content and they just were kept under different hydrostatic pressure, thus it can be resulted that browning reaction has been influenced by storage pressure. Browning reaction was significantly suppressed by the pressure at 50–200 MPa with the activation volume of 13–27 ml/mol (Toru, Noriichi, & Rikimaru, 1991). Also it has been shown that high hydrostatic pressure affected the formation of intense chromophores formed from pentoses and primary amino acids (Frank, Heberle, Schieberle, & Hofmanu, 2000) and the formation of volatile components of a glucose/lysine model system (Hill, Isaacs, Ledward, & Ames, 1999). The effect of pressure on Maillard reaction may be attributed to this fact that the first stage, formation of the Amadori rearrangement product, is accelerated by pressure while the second stage, its degradation, is retarded. The Amadori rearrangement product is formed rapidly but decomposes more slowly under high pressure conditions (Bristow & Isaacs, 1999). Also Figs. 1 and 2 show browning rate in glucose syrups with pH 5 and 6 stored at 25 °C (Fig. 1b and c) and 45 °C. As shown in these figures, the results obtained from browning T= 25°C, 25% CO2
T= 25°C, 75% CO2
T= 45°C, 25% CO2
T= 45°C, 25% CO2
3.5 3.0
Absorbance
372
2.5 2.0 1.5 1.0 0.5 0.0 0
2
4
6
8
10
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14
16
18
20
Time (week)
Fig. 3. Influence of CO2 on color formation in glucose syrups with pH 5 stored at 25 °C and 45 °C.
A. Raisi, A. Aroujalian / Journal of Food Engineering 80 (2007) 370–373 Table 2 Shelf lives for glucose syrups stored at 45 °C under various storage conditions pH 4
pH 5
pH 6
Air
Time (week) to abs. = 3.72 Time (week) to abs. = 0.9
16.6 1.5
19.5 2.1
15.0 1.3
90% N2/10% O2
Time (week) to abs. = 3.72 Time (week) to abs. = 0.9
18.1 2.4
20.9 2.8
16.6 2.1
100% N2
Time (week) to abs. = 3.72 Time (week) to abs. = 0.9
19.6 3.0
22.6 3.5
18.0 2.9
Vacuum
Time (week) to abs. = 3.72 Time (week) to abs. = 0.9
21.8 3.6
26.1 4.5
20.3 3.5
rate of syrup with pH 4 were similar to other pH values. Also browning rate for syrups stored under CO2 were similar to all syrups stored under 100% N2, results shown in Fig. 3. Shelf lives for glucose syrups with pH 5 stored at 45 °C under air, 90% N2/10% O2, 100% N2 and vacuum condition were 16.6, 18.1, 19.6 and 21.8 weeks, respectively while no color formation was observed in glucose syrups stored at 25 °C under these storage conditions. Shelf lives values for all syrups under above conditions are presented in Table 2. 4. Conclusion Maillard reactions are the main causes of brown color formation in glucose syrup. Oxygen and pressure were affected the Maillard reaction. In the absence of oxygen, browning rate in glucose syrup samples was low while it enhanced with increase in oxygen content. Under vacuum pressure, browning rate was very low while it increased under atmospheric pressure. The longest shelf lives of stored glucose syrups were about 26 weeks at pH 5 and the shortest shelf lives were 15 weeks at pH 6 for syrups stored at 45 °C, respectively. For syrups stored at 25 °C, no color formation was observed. This study shows modified atmospheric packaging (MAP) is a useful system to enhance the shelf lives of the glucose syrups. Acknowledgements The authors would like to thank Glucosan Co. (Tehran, Iran) for supplying glucose syrup. References Bostan, A., & Boyacioglu, D. (1997). Kinetics of non-enzymatic color development in glucose syrups during storage. Food Chemistry, 60(4), 581–585. Bristow, M., & Isaacs, N. S. (1999). The effect of high hydrostatic pressure on the volatile products in a model Maillard reaction. Journal of Chemical Society, Perkin Transactions 2, 2213–2218.
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CRA (1985). E48 PH measurement method. Washington, DC: Corn Refiners Association Inc. Frank, O., Heberle, I., Schieberle, P., & Hofmanu, Th. (2000). Influence of high hydrostatic pressure on the formation of intense chromophores formed from pentoses and primary amino acids. International Congress Series, 1245(November), 387–388. Harte, B. R., & Gray, J. I. (1987). The influence of packaging on product quality. In J. I. Gray, B. R. Harte, & J. Miltz (Eds.), Food productpackage compatibility proceedings (pp. 17). Lancaster, Pennsylvania: Technomic Publishing Co. Inc. Hayase, F., Shibuya, T., Sato, J., & Yamamoto, M. (1996). Effects of oxygen and transition metals on the advanced Maillard reaction of proteins with glucose. Bioscience, Biotechnology & Biochemistry, 60, 1820–1825. Hill, V. M., Isaacs, N. S., Ledward, D. A., & Ames, J. M. (1999). Effect of high hydrostatic pressure on the volatile components of a glucose– lysine model system. Journal of Agricultural and Food Chemistry, 47(9), 3675–3681. ISI (1999). ISI 24-1e Determination of Protein by Kjeldah. Science Park Aarhus, Denmark: International Starch Institute. Kearsley, M. W. (1978). The control of hygroscopicity, browning and fermentation in glucose syrups. Journal of Food Technology, 13, 339–348. Kearsley, M. W., & Brich, G. G. (1985). The chemistry and metabolism of the starch based sweeteners. Food Chemistry, 16, 191–207. Knecht, K. J., Lyons, T. J., Thorpe, S. R., & Baynes, J. W. (1992). Role of oxygen in the crosslinking and chemical modification of protein by glucose. Diabetes, 41(2), 42–48. Knecht, K. J., Lyons, T. J., Fu, M. X., Blackledge, J. A., Thorpe, S. R., & Baynes, J. W. (1994). Glycation, glycoxidation and crosslinking of collagen by glucose; kinetics, mechanisms and inhibition of late stages of Maillard reaction. Diabetes, 43, 676–683. Litchfield, J. E., Thorpe, S. R., & Baynes, J. W. (1999). Oxygen is not required for browning and crosslinking of protein by pentoses: relevance to Maillard reactions in vivo. International Journal Biochemistry and Cell Biology, 31(11), 1297–1305. Meydav, S., Saguy, I., & Kopelman, J. I. (1977). Browning determination in citrus products. Journal of Agricultural and Food Chemistry, 25(3), 602–604. Rada-Mendoza, M., Villamiel, M., & Olano, A. (2002). Dissolved air effects on lactose isomerisation and furosine formation during heat treatment of milk. Lait, 82(5), 629–634. Ramchander, S., & Feather, M. S. (1975). Studies on the mechanism of color formation in Glucose Syrups. Cereal Chemistry, 52, 167–173. Rizzi, G. P. (1994). The Maillard reaction in foods. Maillard reactions. In T. P. Labuza, G. A. Reineccius, V. M. Monnier, J. O’Brien, & J. W. Baynes (Eds.), Chemistry, food and health (pp. 11). The Royal Society of Chemistry. Robertson, G. L. (1993). Shelf life of foods. In H. Huges (Ed.), Food packaging: principles and practice (pp. 339). NewYork: Marcel Dekker. Sapers, G. M. (1993). Browning of foods: control by sulfites, antioxidants and other means. Food Technology, 47(10), 75–84. Toru, T., Noriichi, I., & Rikimaru, H. (1991). High pressure effect on Maillard reaction. Agricultural and Biology Chemistry, 55(8), 2071–2074. Yeboah, F. K., Alli, I., & Yaylayan, V. A. (1999). Reactivities of D-glucose and D-fructose during glycation of bovine serum albumin. Journal Agricultural Food Chemistry, 47, 3164–3172. Yeboah, F. K., Alli, I., Yaylayan, V. A., Konishi, Y., & Stefanowicz, P. (2000). Monitoring glycation of lysozyme by electrospray ionization mass spectrometry. Journal Agricultural Food Chemistry, 48, 2766–2774. Ziderman, I. I., & Friedman, M. (1985). Thermal and compositional changes of dry wheat gluten-carbohydrate mixtures during simulated crust baking. Journal of Agricultural and Food Chemistry, 33, 1096–1102.