Anders Leufvén

The effect of sugars and pectin on flavour release from a soft drink-related model system

Abstract Three types of sugar and high-methoxyl pectin at different concentrations were added to a soft drink-related model system consisting of water and six flavour compounds. The addition of these ingredients contributes to changes in viscosity and water activity, which in turn affects the release of the flavour compounds to the gas phase above the soft drink. In the study, a higher concentration of sucrose and invert sugar increased the release of five flavour compounds, probably owing to a so-called “salting-out” effect. Starch syrup at a concentration of 60% increased the amount of three of the flavour compounds released and would probably increase the release of more compounds at a higher concentration. When pectin was added to the system, it was seen that viscosity does not influence release of the flavour molecules, but that the kind of stabiliser used is more important.

The influence of α-tocopherol concentration on the stability of linoleic acid and the properties of low-density polyethylene

In food packaging applications where low-density polyethylene (LDPE) film containing α-tocopherol is used, the antioxidant may have a dual function, i.e. to protect the polymer from oxidative degradation during processing, and to delay the onset of oxidation of the packaged foodstuff during storage. Incorporation of high levels of α-tocopherol into LDPE film was found to inhibit oxidation of a linoleic acid emulsion stored in contact with the film at 6°C. However, the presence of 360 ppm caused changes in mechanical properties and an increase in oxygen transmission. Levels as high as 3400 ppm α-tocopherol also caused yellowing and reduction in crystallinity of the material. Thus, the use of high amounts of α-tocopherol in LDPE, which might be needed in active packaging applications, requires careful consideration of the protective requirements for each specific food and the maintenance of the desired properties of the packaging material. Copyright

Mobility of α‐tocopherol and BHT in LDPE in contact with fatty food simulants

The migration/sorption behaviour of butylated hydroxytoluene (BHT) and a‐tocopherol was studied in packaging material in contact with fatty food simulants. Two low‐density polyethylene (LDPE) films, containing either BHT or a‐tocopherol as antioxidants, were stored in contact with sunflower oil or 95% (v/v) ethanol. The antioxidant content was monitored in the films throughout a period of 7 weeks. The migration of a‐tocopherol into the food simulants was slower than that of BHT. Since a‐tocopherol was transferred from the film to the simulant to a lesser extent, it is considered to be a more stable antioxidant than BHT when used in an LDPE film in contact with 95% ethanol or sunflower oil.

Migration of model contaminants from PET bottles: influence of temperature, food simulant and functional barrier

To simulate post-consumer recycled plastics, selected model contaminants were incorporated into PET bottles using a time saving method. Migration into 3% acetic acid, a cola-type beverage and 95% ethanol was followed during 1 year of storage at 20 and 40°C. Aroma compounds previously found in post-consumer PET material were used as model contaminants. Benzaldehyde was found to migrate to the highest extent. Storage at 40°C affected the bottle material and this might be one reason for the high migration values of these bottles. Migration into ethanol was up to 20 times higher than into 3% acetic acid or a cola-type beverage. Bottles with a functional barrier resisted migration into food simulants even when filled with 95% ethanol and stored for 1 year at 40°C. Differential scanning calorimetry measurements showed that ethanol was interacting with the plastic material. This resulted in a lower glass transition temperature of bottles stored with ethanol compared with bottles stored empty or with other food simulants.

Identification of chemicals, possibly originating from misuse of refillable PET bottles, responsible for consumer complaints about off-odours in water and soft drinks

Mineral water and soft drinks with a perceptible off-odour were analysed to identify contaminants originating from previous misuse of the refillable polyethylene terephthalate (PET) bottle. Consumers detected the off-odour after opening the bottle and duly returned it with the remaining content to the producers. The contaminants in question had thus been undetected by the in-line detection devices (so-called ‘sniffers’) that are supposed to reject misused bottles. GC-MS analysis was carried out on the headspace of 31 returned products and their corresponding reference products, and chromatograms were compared to find the possible off-odour compounds. Substances believed to be responsible for the organoleptic change were 2-methoxynaphthalene (10 bottles), dimethyl disulfide (4), anethole (3), petroleum products (4), ethanol with isoamyl alcohol (1) and a series of ethers (1). The mouldy/musty odour (5 bottles) was caused by trichloroanisole in one instance. In some cases, the origins of the off-odours are believed to be previous consumer misuse of food products (liquorice-flavoured alcohol, home-made alcohol containing fusel oil) or non-food products (cleaning products, petroleum products, oral moist snuff and others). The results also apply to 1.5-litre recyclable PET bottles, since the nature and extent of consumer misuse can be expected to be similar for the two bottle types.

Effect of changes in pH on the release of flavour compounds from a soft drink-related model system

Abstract Citric acid and phosphoric acid were added in variable amounts to a soft drink model system to show their effect on the release of six flavour compounds. High concentrations of the acids decreased the release of esters, probably because of the presence of large amounts of the dissociated form of the acids. However, the same amounts of added citric acid had no effect on flavour release when pH was regulated with sodium hydroxide. Changes in pH values achieved by adding hydrochloric acid also had no effect on flavour release. These results indicate that pH values used in soft drinks do not affect the release of flavour molecules. It is more likely the citric acid and the phosphoric acid, particularly their dissociated forms, which decrease the release of the esters. The other flavour compounds were not affected.

Influence of trace metals, acids and ethanol in food-simulating liquids on the retention of α-tocopherol in low-density polyethylene film

The retention of alpha-tocopherol (vitamin E) in lowdensity polyethylene (LDPE) film was investigated when in contact with different food-simulating liquids. Variations of the aqueous food simulants approved by the EU for testing of interactions between packaging materials and food, and an alternative fatty food simulant (95% aqueous ethanol) were used to study the influence of trace metals and acids, as well as variation in pH and ethanol concentration, on the stability of α-tocopherol in the L DPE film. The presence of trace metals in aqueous media accelerated loss of α-tocopherol from the film, while the addition of citric or ascorbic acid counteracted this loss. In contact with aqueous ethanol at a concentration of 50% or higher, the loss of α-tocopherol from the film was total. However, with solutions containing less than 50% ethanol, the antioxidant was almost completely retained in the film, unless the temperature was increased from 6 to 40°C. For contact with solutions containing ethanol or trace metals, an increase in temperature resulted in a greater loss α-tocopherol from the LDPE film.

Active product packaging flavour interaction

Abstract The utilisation of polymer films, made from latex, onto food packaging with the aim to achieve different packaging functionalities was studied. Emphasis was given to the course of volatile compounds that affect food flavour, their adsorption, release from and distribution in hydrocolloid dispersion coatings as well as the aroma barrier properties of hydrocolloid dispersion coatings. Preliminary results indicate that the adsorption and retention during of polar and non-polar aroma compounds is different for different latex films. Furthermore, the chemical features of the aroma substances affect how they adhere to polymeric substrates.