The scientists, who published their findings in the Journal of Food Process Engineering, said they were motivated to evaluate the factors that interfere in the stability of chewing gums, based on the fact that there is a scarcity of data in the literature on the subject.
Worth $23bn annually, the global gum market has grown by almost a quarter since 2005. But a major challenge in the production of chewing gum relates to its shelf life, continued the authors, and they cite frequent problems related to texture that can arise during storage:
“The gum can become too soft and stick to the packaging material, or become too hard, presenting high resistance to chewing,” they argue.
The team said their goal was to determine the effect of some ingredients and storage conditions on the stability of chewing gums, and they thus investigated citric acid and lactic acid concentrations, as well as the effect of the addition of sodium lactate.
Glucose syrup, base gum, lecithin and glycerin were mixed until a homogeneous mass was obtained, what occurred in approximately 4 minutes. The dye, citric and lactic acids, sodium lactate and sugar were then added and the mixture was homogenized in the mixer for 5 minutes, said the team.
Finally, the aroma was added and the mass was mixed for another 4 minutes. The temperature of the mass was kept at 50°C during all the mixing process. After preparation, the mass was kept at 45°C for 60 minutes, said the researchers.
Mass strings were manually shaped and cooled in an industrial cooling tunnel. The product was packed in an automatic packing machine, using internal wrap of bi-oriented polypropylene and external film of multilayer polyolefin, commonly used in chewing gum packing.
The authors said that all the formulations were carried out in a controlled environment (25°C and 60 per cent relative humidity (RH)) to avoid influence of weather oscillations in experimental runs.
The products obtained were stored in plastic beakers that were placed in sealed plastic boxes. Each box simulated a different RH condition using saline solutions. A saturated MgCl2, 40 per cent H2SO4 and 22 per cent CaCl2 were used to obtain RH of 30, 55 and 80 per cent respectively.
And the boxes, said the researchers, were kept in a temperature-controlled chamber at 35°C with physical–chemical analyses of samples carried out right after preparation and after 30, 60, 90, 120, 150 and 180 days of storage.
The samples were assayed, they added, for pH, moisture, mass gain, water activity, concentration of sugars (glucose, fructose and sucrose), total sugar reduction and the visual aspect of the product.
The RH at storage was the factor that most influenced the mass gain/loss by the product, followed by the total acid concentration and the ratio between the citric and lactic acid, noted the team.
They said that addition of sodium lactate presented a negative significant effect, confirming the ability of this salt to act as a buffering agent, hindering sucrose inversion and consequent water absorption by the product.
The most impressive change was observed in the condition of highest RH (80 per cent), where the samples became sticky after the 90th day of storage, found the authors. “During storage at 30 per cent RH, the product became gradually harder, making chewing more difficult,” they added.
An expressive acceleration of cold melt and glucose and fructose concentration was verified in the samples with 1 per cent of citric acid, without the addition of sodium lactate and in the samples with 0.8 per cent of lactic acid, 0.2 per cent of citric acid and without the addition of sodium lactate. “The latter was already sticky after 60 days of storage.”
The addition of sodium lactate (1.08 per cent dry basis) to the formulation favored stability of the product, as well as the use of lactic acid, instead of citric acid, concluded the researchers.
Source: Journal of Food Process Engineering
Published online ahead of print
Title: Evaluation of Sugar Inversion in Chewing Gum added of (sic) Sodium Lactate
Authors: E Valduga, M. Roberto, Lazzari, R. Vardanega, M. Di Luccio