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E. T. Contis et al. (Editors) Food Flavors: Formation, Analysis and Packaging Influences © 1998 Elsevier Science B.V. All rights reserved

753

Identification of the source of an off-odor in premiums intended for use with dry mix beverages Dimitrios Apostolopoulos Kraft Foods, Technical Center, Packaging Research and Technology, 801 Waukegan Road, Glenview, IL 60025, USA

Abstract Premiums intended to be inserted inside packaged dry mix beverages were tested for off-odor. Headspace gas chromatography/mass spectrometry was used in combination with an odor test to identify the volatiles in the premiums and also evaluate the odor barrier characteristics of the overwrap film. Data obtained from the headspace analysis of unwrapped premiums showed extraordinarily high amounts of chemicals with the major residual component being identified as cyclohexanone. Toluene, 2-methyl heptane, and 3-methyl hexane were the next sizable components. The source of those residual chemicals was considered to be solvents used with either the resin or the paint employed in the manufacturing and painting of the premiums. Odor testing of unwrapped premiums demonstrated a very strong, "solvent-like", objectionable odor. Residual cyclohexanone in overwrapped premiums was found to be about 16 times less than in the unwrapped premiums. Furthermore, the overwrapped premiums exhibited no off-odor. This clearly suggested that the solvent barrier provided by the plastic film used for overwrapping of the premiums was sufficient to prevent any residual solvent contamination of the dry mix beverages. It is apparent, however, that an unsealed premium overwrap or a premium with a punctured overwrap film would allow significant amounts of residual cyclohexanone and other residual solvents to transfer into the packaged contents and cause a severe off-odor problem. For that reason, it was recommended that those premiums should not be used with packaged dry mix beverages.

1. INTRODUCTION A common promotional tool is the insertion of a premium inside a food package. The volafiles in these inserts, if not controlled, can impart an undesirable flavor to packaged foods. Common practice is the use of an overwrap film to prevent direct contact and contamination of the product (1). The present study was undertaken with the objecfive to identify any product quality issues associated with the insertion of premiums inside packaged dry mix beverages. More specifically, i) identify any volatiles of the premiums that could potentially impart an off-odor

754

to the dry mix beverages, ii) quantify the odor impact of such volatiles upon their potential transfer into the product, and iii) determine whether the barrier provided by the premium overwrap film was sufficient to prevent transferring of the premium volatiles into the packaged contents. 2. MATERIALS AND METHODS 2.1 Premiums The premium samples under evaluation were molded polyethylene bodies shaped as potato men and women, which were painted and sealed in a nylon overwrap film. 2.2 Identification of Residual Species Present in Premiums by Using Headspace Gas Chromatography/Mass Spectrometry The identification of residual species present in the premiums under evaluation was performed in accordance with the ASTM F 151-86 method, modified as described below. Two over wrapped or two unwrapped premiums were placed into half-quart Mason jars. The jars were fitted and sealed with teflon-lined lids, equipped with sampling ports. Mason jars containing the premium specimens were placed inside a mechanically convected oven and heated at 110°C for 90 minutes, to ensure vaporization of the premium residuals into the headspace of the Mason jars. Using a preheated gas-tight syringe to avoid condensation of the volatiles, headspace aliquots of ImL were withdrawn from the Mason jars and injected into a gas chromatograph/mass spectrometer (GC/MS), equipped with a CP-Sil 8 CB chromatographic column operated at 20°C for 2 minutes and then increased at 10°C/min to 250°C. The compounds present in the injected aliquots were separated resulting in GC/MS scans with tentative mass spectral identification presented in Figures 1, 2, and 3.

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Figure 1: GC/MS profile of residual compounds for overwrapped premiums

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Figure 2: GC/MS profile of residual compounds for unwrapped premiums

Overwrapped Premiums

Figure 3: GC/MS profile of residual compounds for overwrapped versus unwrapped premiums

2.3 Odor Test The odor test was performed as described below. Three overwrapped or unwrapped premiums were placed in thoroughly cleaned one quart Mason jars, sealed with aluminum foil lined lids and heated at 49°C for 1 hour. Blanks (empty jars) were prepared and carried through the entire odor test to assure against any extraneous odors resulting from the jars or the screw caps. The Mason jars containing the premium specimens, as well as the blanks, were cooled to room temperature and then presented to an experienced panel for odor evaluation. The panel was composed of four people. All the panel menbers were familiar with the odor of solvents commonly used by the packaging industry. Odor evaluation entailed removing the screw caps of the Mason jars, opening a hole through the aluminum foil to allow sniffing of the headspace and determinating the odor givenoff by the premiums.

756 The odor evaluation panel was asked to briefly describe the type of odor present, rate the odor intensity on a 0-10 scale, and also indicate whether the odor was objectionable or not. 3. RESULTS AND DISCUSSION As indicated by the GC/MS profiles presented in Figures 1 and 2, both the overwrapped and unwrapped premiums exhibited a rather large number of residual compounds. The most abundant of all the residual compounds identified was cyclohexanone, followed in concentration by toluene, 2-methyl heptane, and 3-methyl hexane. The source of such residual chemicals was considered to be either the polyethylene resin or the paint used with the premiums. A comparison of the GC/MS profiles of the overwrapped and unwrapped premiums showed that the amount of cyclohexanone given-off by the unwrapped premiums was about 16 times more than the amount of cyclohexanone displayed by the overwrapped premiums (See Figure 3). This clearly suggested that the plastic film used for overwrapping of the premiums possessed very good solvent barrier characteristics and provided sufficient protection against any odor transfer under this test procedure. The conclusion above was also supported by the results of the odor test. Overwrapped premiums exhibited essentially no odor at all, unlike their unwrapped counterparts which exhibited a very strong solvent-like, objectionable odor, as shown by the table below. Table 1 Results of Odor Test for Premiums Type of Premium Overwrapped Unwrapped

Type of Odor

Odor Intensity on a 0-10 Scale*

None

0

Very strong, solvent-like, objectionable

* Where: 0 corresponds to essentially no odor characterized as objectionable

9

and

8-10 to excessive odor, usually

Based on the data generated, it can be stated that the overwrapped premiums inserted in the package were expected to contribute no odor to the dry mix beverage. However, the same data suggests that an occasionally unsealed or punctured overwrap could allow significant amounts of residual cyclohexanone, as well as other odorous residual compounds to transfer very easily into the packaged contents and cause a severe off-odor problem. For that reason, it was recommended that those premiums not be used in dry mix beverage packages.

757 4. REFERENCES 1. M.G. Heydanek, Jr., G. Woolford, and L.C. Baugh, J. Food Sci., 44 (1979) 850 2. ASTM Designation: F151-86. Standard test method for residual solvents in flexible barrier materials, (1986) 812-816.