Measurement of Flavor Absorption from Soft Drinks

International Journal of Food Engineering Volume 7, Issue 4

2011

Article 11

Measurement of Flavor Absorption from Soft Drinks into PET Bottle by Headspace Solid Phase Microextraction-Gas Chromatography Mehdi Farhoodi, University of Tehran Maryam Salami, University of Tehran Zahra Emam-Djomeh, University of Tehran SM Mohammad Mousavi, University of Tehran Karamatollah Rezaei, University of Tehran

Recommended Citation: Farhoodi, Mehdi; Salami, Maryam; Emam-Djomeh, Zahra; Mousavi, SM Mohammad; and Rezaei, Karamatollah (2011) "Measurement of Flavor Absorption from Soft Drinks into PET Bottle by Headspace Solid Phase Microextraction-Gas Chromatography," International Journal of Food Engineering: Vol. 7: Iss. 4, Article 11. DOI: 10.2202/1556-3758.2031 Available at: http://www.bepress.com/ijfe/vol7/iss4/art11 ©2011 Berkeley Electronic Press. All rights reserved.

Measurement of Flavor Absorption from Soft Drinks into PET Bottle by Headspace Solid Phase Microextraction-Gas Chromatography Mehdi Farhoodi, Maryam Salami, Zahra Emam-Djomeh, SM Mohammad Mousavi, and Karamatollah Rezaei

Abstract Absorption of flavors into packaging is of great importance in the food industry because of the final quality needs of the product. In the present study one-sided exposure of D-limone, αPinene and myrcene from three types of carbonated drinks into PET bottles was studied at different test temperatures (4, 25 and 40°C). Headspace solid-phase microexraction was used as a technique for extracting the absorbed flavors from PET and the analysis performed by gas chromatography coupled with FID detector. The results showed that the absorption level of flavors is dependent on the structure and initial concentration of the flavors, media type and storage temperature. The flavors stored at 4°C showed higher consistency in the media, but the absorption rate of flavors enhanced with increasing temperature. KEYWORDS: absorption, polyethlene terephthalate (PET), solid phase microexraction (SPME), D-limonene, myrcene, pinene

Farhoodi et al.: Measurement of Flavor Absorption from Soft Drinks into PET Bottle

1. Introduction Polymeric packaging materials due to their relatively low cost compared to metal or glass packages have become popular. Polyethylene terephthalate (PET) is produced by a condensation reaction of ethylene glycol and terephthalic acid. It is a widely used packaging material that offers good mechanical strength, moisture barrier and chemical resistance (Brandsch et al., 2000; Brooks, 2002; Brooks and Giles, 2002). In spite of growing demand for polymeric materials, interaction between the food and package is an important concern for the food industry. Absorption of flavors from food into the polymeric packaging material influences the sensory quality of packaged food. Flavor of a drink provides not only a generic identity for the product but also is an index of drink quality (Ashurst, 1998). So, it is important to estimate the rate of flavor absorption into packaging material in order to determine an appropriate shelf life for the product (Wright, 1999). Extensive studies have been done on the interactions between PET bottles and packaged food. Some research has been focused on the migration of volatile compounds from plastic material into food (Monarca et al., 1994; Nawrocki et al., 2002; Biscardi et al., 2003; Farhoodi et al., 2008). On the other hand, the absorption of flavors from food into the packaging material has also been investigated by some authors. Arora (1991) studied the absorption of flavor compound by low density polyethylene. Nielsen (1994) analyzed the absorption of myrcene and limonene into refillable PET bottles. Tawfik (1998) studied the effect of D-limonene absorption on the mechanical properties of refillable PET bottles. Mousavi (1998) recommended a model for the migration of volatile compounds into packaged food via package free space. Van Willage (2000a and 2000b) studied the Influence of food matrix (proteins, carbohydrates, oil and real food product) on absorption of flavor compounds by liner low density polyethylene. Nielsen (2006) studied the factors affecting the absorption of aroma compounds into low-density polyethylene and Sheung et al. (2006) proposed a mathematical model to determine the diffusion coefficient of orange juice flavor compounds into packaging materials. Solid phase microextraction (SPME) is a relatively new established method for sample preparation in the analysis of volatile compounds in different kind of matrices. SPME is a solvent free and rapid method, which allows direct analysis of the volatile component from solid phase. Volatiles are captured by SPME based on the theory of equilibrium partitioning of the analytes between the solid phase of SPME, the solid matrix and the headspace above the matrix can be analyzed by gas chromatography (GC). SPME has been applied for the flavor sampling in the various kinds of foods such as cheese, oil and mustard (Frank and Owen, 2004; Zhao et al., 2006; Chena et al., 2007).

Published by Berkeley Electronic Press, 2011

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International Journal of Food Engineering, Vol. 7 [2011], Iss. 4, Art. 11

D-limonene, myrcene and pinene are water dispersible flavors which participate in the taste of soft drinks. The objective of this study was to investigate the effect of time, temperature and drink type on the absorption of flavors from soft drinks into PET bottles. 2. Experimental part 2.1 Materials The analytes used in this research were D-limonene, myrcene and pinene (Merck Co., Germany). The properties of flavors used in the soft drink are listed in table 1. The soft drinks used in this study (Limonene, cola and Orange) produced in the research laboratory of Zam Zam company. The final drinks were packed in 300ml PET bottle and stored in three different temperatures (4, 25 and 40ºC). Table 1 The properties of flavors used in this study. Name

Molecular Formula

Molecular weight (g/mol)

Structure H3C

D-limonene

C10H16

136.23

CH3 H2C

CH2

Myrcene

C10H16

136.23

CH3

H2C CH3

CH3

Pinene

C10H16

136.23 H2C H2C

2.2 Sample preparation To prepare the soft drinks the ingredients (sugar, citric acid, sodium benzoate and the flavor extracts) mixed together with a specific ratio. The carbonated water added to the mixture using a carboculer (Hook Co, Switzerland) under the pressure 3.5 psi and the temperature 4°C. The characteristics of drinks are shown in table 2.

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Table 2 The characteristics of the drinks

Name

pH

Dominant Acid

CO2 (gr/100 ml)

Flavor content (mg/l) D-limonene

Myrcene

α-pinene

Cola

2.5

Phosphoric acid

0.7

5.05

0.16

0.27

Orange

3

Citric acid

0.6

25.50

0.48

0.15

Limone

3

Citric acid

0.6

6.8

0.16

0.12

2.3 Instrumental Analyses The bottle was cut into small pieces (100mm2) after the soft drink was removed and the plastic pieces were washed with distilled water. SPME analysis were carried out with SPME fibers (Supelco Co. Bellefonte, USA) coated with poly (dimethyl siloxane) (PDMS, 100 mm). Prior to the analysis, the PDMS fiber was conditioned at 350 ºC for 30 min in a GC injection port. GC analyses were performed using a Shimadzu 2010 gas chromatograph equipped with an FID and a DB-5 fused silica capillary column (30m×0.22mm i.d. and 0.25 mm film thickness). The analytes were injected into the GC using split/splitless injection port in the splitless mode at 300ºC with splitless time 2 min. The oven temperature was held at 35ºC for 4 min, then programmed at 10°Cmin-1 to 80ºC and then at 3°Cmin-1 to 110ºC and maintained in this temperature for 3 min. Ultra pure helium was used as a carrier gas at constant linear velocity of 30 cms-1. All the samples were analyzed in duplicate. The determination of calibration curve is a crucial point in the experiment, therefore in order to express the area under each curve in terms of concentration, calibration curve was determined with known concentrations of flavors. 3. Results and discussion The amounts of flavors (D-limonene, myrcene and α-pinene) are listed in the table 2. It is clear that D-limonene considered as dominant flavor in all soft drinks because of the higher initial concentration in the formulation.


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3.1 Effect of initial concentration Undoubtedly the concentration gradient between the packaging material and the drink is an important factor causing the flavors to absorb into package. Tawfik et al. (1998) concluded that the absorption of flavors into PET during storage time depends on the initial concentration of the flavor. He found that the amount of flavor absorption from the model solution containing 320 ppm D-limonene was higher than the one containing 160 ppm. It has been reported that absorption of limonene from the orange juice with 177 mg litre-1 limonene was about 30 ppm (Imai et al., 1990) while it was 9.9 ppm from the orange juice with 60 mg litre-1 limonene (Nielsen, 1994). At the present study D-limonene was the only flavor that was absorbed into the PET bottles in all the specimens (orange, limonene and cola drinks). Because of the low concentration of myrcene and α-pinene in the primary solution, the absorption of these constituents was not detectable and the study has been focused on the D-limonene absorption as a function of time and temperature. 3.2 Effect of storage temperature Table 3 displays the amount of D-limonene absorption from orange, lemon and cola drinks into PET bottles at three test temperatures. At the first hours of the study, in all three samples the absorption rate was temperature dependant and after 45h storage, the samples stored at 40°C absorbed higher level of D-limonene than the samples stored at 4 and 25°C. At higher temperatures, increased free volume of the polymer resulted in molecules’ easier absorption. Smililar results were observed in the findings of Aroral (1991), Tawfik et al. (1998), Van Willige et al. (2001). Nielsen et al. (1992) found that temperature influenced the absorption of flavor compounds by LDPE significantly. They suggested that the higher absorption was from the greater mobility of the flavor compunnds, or the swelling of the polymer at higher temperatures, creating more space for solvation of the flavor molecules. Table 3 Absorption of D-limonene from orange, lemon and cola drinks into PET bottles (ng/g) at different temperatures as a function of time Time (h)

4°C

25°C

45°C

Orange

Lemon

Cola

Orange

Lemon

Cola

Orange

Lemon

Cola

0 45 90 120

0.00 11.36 17.54 17.01

0.00 0.41 2.00 3.11

0.00 13.22 22.08 24.26

0.00 19.15 26.67 46.61

0.00 3.50 5.12 3.33

0.00 15.56 30.06 36.93

0.00 46.70 27.92 17.01

0.00 6.81 2.41 0.38

0.00 20.55 7.14 4.26

145

23.24

3.93

28.25

37.10

1.60

23.47

9.84

0.01

2.84

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3.3 Effect of drink type The maxiumum absorption of D-limonene was observed for the orange drink stored at 25°C after 145h. Fig. 1 compares the absorption of D-limonene from three different media into PET bottles at similar storage temperature. For all the samples, absorption continued during the entire period of storage at 4°C. After 145h storage at 4°C, the absorption of D-limonene from lemon drink reached to a higher level than orange and cola drinks. At 25 and 45°C the absorption mechanism was different than 4°C. At 25°C the absoption of D-limonen decreased after 120h storage for orange and cola drinks and after 90h of storage for lemon drink. At 45°C for all the samples, the absorption of D-limonene into PET bottles decreased after 45h of storage. Limonene is a relatively stable terpene, which can be distilled without decomposition, although at elevated temperatures it cracks to form isoprene (Pakdela et al., 2001). It oxidizes easily in moist air to carveol and carvone (European Chemicals Bureau). The most widely practiced conversion of limonene is to carvone. When the component was warmed with mineral acid, limonene isomerizes to the conjugated diene α-terpinene, which can itself easily be oxidized to p-cymene, an aromatic hydrocarbon (fig. 2). So it means by increasing the temperature from 4 to 25 and 40 °C the conjugation will happen and the concentration of D-limonen will decrease in solution. The reaction took place faster in high temperature and as a result a very sharp and fast inverse in absorption was appeared as shown in fig. 3. Furthermore evidence for isomerization includes the formation of Diels-Alder α-terpinene adducts when limonene is heated with maleic anhydride.


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D‐limonene absorption (ng/g)


30 25 20 15 10 5 0

4°C

Lemon Orange Cola 0

47

89

121

144


Time (Hour) 50

25°C

40 30 20

Lemon

10

Orange

0

Cola 0

47

89

121

144

Time (hour)


50

45°C

40 30 20

Lemon

10

Orange

0

Cola 0

47

89

121

144

Time (hour)

Fig.1 Absoption of D-limonene into PET bottle at 4, 25 and 45 °C http://www.bepress.com/ijfe/vol7/iss4/art11 DOI: 10.2202/1556-3758.2031

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CH3

H3C

CH2

d-limonene

CH3

CH3

H3C

CH2

α-terpinene

H3C

CH2

p-cymene

Fig.2 Conversion of D-limonene to α—terpinene and p-cymene Fig. 3 shows that in each drink, the effect of acidic media was enhanced with increasing temperature, so the reduction in d-limonene occurred sooner at elevated temperatures. For example in orange drink which had the highest initial level of D-limonene (table 2), inverse in the absorption of limonene was observed after 120 h of storage at 25°C while the same effect was observed after 45 h for the samples stored at 40°C. Similar results were observed for cola and lemon drinks which were stored at 25 and 40°C. The samples stored at 4°C showed an even increasing trend in limonene absorption which indicated that the isomerization of limonene did not occur at low temperatures.


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Absorption (ng/g)

60

Orange Drink

50 40 30

4°C

20

25°C

10

40°C

0 ‐50

0

50

100

150

200

Absorption (ng/g)

Time (h) 8 7 6 5 4 3 2 1 0

‐50

Lemon drink

4°C 25°C 40°C

0

50

100

150

200

Time (h) 40

Cola

Absorption (ng/g)

35 30 25 20

4°C

15

25°C

10

45°C

5 0

‐50

‐5 0

50

100

150

200

Time (h)

Fig.3 Absorption of D-limonene from orange, lemon and cola drinks into PET bottle http://www.bepress.com/ijfe/vol7/iss4/art11 DOI: 10.2202/1556-3758.2031

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4. Conclusions SPME provided an accurate and rapid test for extracting flavor compounds from PET. The results showed that the drink type is important in stability and constancy of d-limonene. In acidic type media like cola, orange and lemon, conjugation occurs and this phenomena is enhanced at elevated temperatures. The maximum amount of conversion happened at 40°C. The results showed that at the first days of storage before the conjugation, the amount of flavor absorption increased with increasing temperature from 4 to 25 and then 40°C which showed that the process is temperature dependent but as time passed, the condition favored for limonene conjugation, and the limonene concentration in the drinks decreased. Lower concentration of limonene in the solution resulted in lower absortption of flavor into PET bottles. References Ashurst, P. R. (1998). Chemistry and Technology of Soft Drinks and Fruit Juices, Introduction: Shffield Academic Press Ltd. Sheffield, England. Arora, D. K., Hansen, A. P. & Armagost, M. S. (1991). Sorption of flavor compounds by low density polyethylene film. Journal of food science, 56 (5), 1421-1423. Biscardi, D., Monarca, S., De Fusco, R., Senatore, F., Poli, P., Buschini, A., Rossi, C. & Zani C. (2003). Evaluation of the migration of mutagens/carcinogens from PET bottles into mineral water by Tradescantia/micronuclei test, Comet assay on leukocytes and GC/MS. The Science of the Total Environment 302, 101-108. Brandsch, J. & Pringer, O. (2000). Plastic Packaging Material for Food, Characteristics of plastic material: Wiley-VCH, Weinhein, Germany. Brooks, D .W. (2002). PET packaging technology, Barrier material and technology: Shffield Academic Press Ltd. Sheffield, England. Brooks, D. W. & Giles, G. A. (2002). PET Packaging Technology, Introduction: Shffield Academic Press Ltd, sheffield, England. Chena, W., Zhou, P., Wong-Moona, K. C. & Cauchona, N. S. (2007). Identification of volatile degradants in formulations containing sesame oil using SPME/GC/MS. Journal of Pharmaceutical and Biomedical Analysis 44 (2), 450-455. European Chemicals Bureau Farhoodi, M., Emam-Djomeh, Z., Ehsani, M. R. & Oromiehie, A. R. (2008). Migration of model contaminants (ethylene glycol, DEHA and DEHP) from PET bottles into Iranian yogurt drink. e-Polymers 037, 1-9.


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Frank, D. C., Owen, C. & Patterson, J. (2004). Solid phase microextraction (SPME) combined with gas-chromatography and olfactometry-mass spectrometry for characterization of cheese aroma compounds. Lebensmittel-Wissenschaft und-Technologie 37 (2), 139-154. Imai, T., Harte, B. R. & Giaicin, J. R. (1990). Partition distribution of aroma volatiles from orange juice into selected polymeric sealant films. Journal of Food Science 55, 158-161. Monarca, S., De Fusco, R., Biscardi, D., De Feo, V., Pasquini, R., Fatigoni, C., Moretti, M. & Zanardini, A. (1994). Studies of migration of potentially genotoxic compounds into water stored in PET bottles. Food and chemical toxicology 32, 783-788. Mousavi, S. M., Desobry, S. & Hardy, J. (1994). Mathematical modelling of migration of volatile compounds into packaged food via package free space. Part I: Cylindrical shaped food. Journal of Food Engineering 36 (4), 453-472. Nawrocki, J., Dabrowska. A. & Borcz, A. (2002). Investigation of carbonyl compounds in bottled waters from Poland. Water Research 36, 4893-4901. Nielsen, T. J., Jagerstad, I. M. & Oste, R E. (1992). Study of factors affecting the absorption of aroma compounds into low-density polyethylene, Journal of the Science of Food and Agriculture 60 (3), 377 – 381. Nielsen, T. J. (1994). Limonene and Mycrene Sorption into refillable polyethylene terephthalate bottles and washing effects on removal of sorbed compounds. Journal of Food Science 59, 227-230. Pakdela, H., Panteaa, D. & Roy, C. (2001). Production of dl-limonene by vacuum pyrolysis of used tires. Journal of Analytical and Applied Pyrolysis 57 (1): 91–107. Sheung, K., Sastry, S. K. & Min, D. B., Diffusion Coefficient of Orange Juice Flavor Compounds into Packaging Materials. LWT 40, 157-163 (2006). Tawfik, M. S., Devlieghere, F. & Huyghebaert, A. (1998). Influence of dlimonene absorption on the physical properties of refillable PET. Food Chemistry 61, 157–162. Van Willage, R.W.G. (2000a). Influence of food matrix on absorption of flavour compounds by linear low-density polyethylene: proteins and carbohydrates. Jouranl of food science 80, 1779-1789. Van Willage, R.W.G. (2000a). Influence of food matrix on absorption of flavour compounds by linear low-density polyethylene: oil and real food products. Journal of Food Science 80, 1790-1797. Wright, J. (1999). Food Flavorings, Essential oils: Aspen publishers, Inc., Gaithersburg, Maryland. Zhao, D., Tang, J. & Ding, X. (2006). Analysis of volatile components during potherb mustard (Brassica juncea, Coss.) pickle fermentation using SPME–GC-MS. LWT 40 (3), 439-447. http://www.bepress.com/ijfe/vol7/iss4/art11 DOI: 10.2202/1556-3758.2031

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