Introduction: Aerated dairy desserts have shown a great market potential as a function of consumer behavior, interested in lighter and healthier relish products. Mousse is an aerated dessert with stabilized foam structure that, although traditionally home-made, is nowadays produces on an industrial scale and is gaining space in the dessert market. The most popular mousse flavor is chocolate followed by orange, lemon and strawberry. The industrial production of aerated dairy dessert is delicate, requiring knowledge about the formation and stabilization of foam, the use of functional ingredients. Food foam is formed by air, liquid and surface-active agent such as proteins. The formation of air bubbles modifies the texture and the rheological properties of aerated food. In aerated confectionery, foams are produced by aeration of a mixture of sugar syrups and proteins. Egg white protein (EW) is the most widely used surface active agent for production of aerated dairy desserts. Foam is a two-phase system in which the diffused phase is air bubbles and the surface phase is formed by a thin layer of proteins with changed nature. These days, consumers prepare ready-made foods, and low-calorie, healthy foods and are more aware of the relationship between a diet and disease. Given the efforts to reduce the incidence of diseases such as cancer, cardiovascular diseases and health improvement, the expansion of plant-rich and anti-cancer foods can play a key role in ensuring health.
Glycyrrhiza glabra (Licorice) is a perennial leguminous plant. The medicinal organ of the plant is constituted of its roots, containing triterpene saponins that has many indications. Licorice is one of the most important medicinal herbs in terms of economics that has been widely studied. The most striking compound of licorice is Glycyrrhizin, and this compound is responsible for licorice sweet flavor that is 50 times sweeter than sucrose. The aqueous extract (essential oil) of licorice root has a variety of applications in pharmacy and food industries due to its functional physical properties. Licorice root extract contain saponins which have surfactant properties. One distinctive property of saponins is that they yield relatively stable, soap-like foam in aqueous solution and can be used to adjust the foam in the food industries to improve the stability of the foam and create flavor and aroma. There is a growing commercial interest in using Liquorice root extract in food foams. However, little is known about the foaming behavior of the extract. Liquorice root extract can be used to modify food foams, to enhance foam stability. It can also be used in the development of new foamy foods.
In general, the present study was carried out to develop a kind of mousse to which a native, local, natural plant ingredient was added and to verify the perspectives of the product with regard to potential for consumer health benefits and textural acceptance, and also to replace part of egg white with licorice as a plant alternative.
Materials and method: The ingredients in the preparation of Mousse are: egg white 15.67 g, sucrose 13.05 g, water 7.31 g, butter 5.57 g, cocoa 2.61 g, sugar powder 3.48 g, cream 52.33 g, vanilla 0.05 and various levels of licorice (12.5, 25, 37.5 and 50 percent), which replaced egg white in the above formulation.
The samples' moisture content, overrun, volume of foam and density was measured. The texture analyzer was used to evaluate the textural attributes of the final product and TPA test was performed.
Results and discussion: The moisture content of samples reduced with increasing the substitution level. The moisture content of the product directly depends on the molecular weight, the type of hydrophobic and hydrophilic factors, and the number of these bonds. The most prominent compound of licorice is glycyrrhizin, a water soluble glycoside terpenoid that cannot be connected to a large amount of water. Therefore, it seems that reducing moisture content with increasing the replacement level is related to this characteristic of licorice.
The highest amount of over run was quantitatively related to the control sample and the lowest amount was related to 50% licorice substitution level. Generally, overrun of samples decreased with increasing the amount of licorice replacement. The reason is the lack of the formation of a complex with Ovotransferrin (which is about 13% in egg white and helps formation of the foam) due to its denaturation. In conducted studies, it has been reported that with increasing the concentration of gum (gum in licorice), the volume of the foam system reduced.
In fact, with increasing the viscosity of the aqueous phase by adding the gum, the air cannot enter the system during the stirring process, and therefore the volume of the system will be less increased. Albumin is a heterogeneous protein system that occurs during the foaming process of protein-protein interactions.
Foam durability index of samples reduced with increasing the amount of the replacement of licorice. This is due to the fact that in low inter-surface tension, the surface covering film does not have sufficient strength, the two adjacent bubbles are easily deformed and undergoes considerable Van der Waals gravity. Thus, the bubbles mixed (coalescence) and the foam lost its stability. In general, licorice is less hydrophobic. This interacts with the formation of the coherent film on the air-water contact surface, which reduces the stability of the foam.
Density of the foam samples increased with increasing the amount of licorice, the density of the foam is in fact a proportion of the diffused phase to the continuous phase and represents the amount of air entering it during the formation of the foam. In fact, the low density of the foam indicates a greater volume increase, and vice versa.
The air phase of the foam samples reduced with increasing the amount of the replacement of licorice. The reason for this is that the use of the replacement of licorice reduced the ability of the foam due to reducing the elasticity of the interface of air bubbles and caused rapid degradation of the foam.
According to the results obtained from the statistical analysis, it was found that with increasing the replacement of licorice in formulation, elasticity, chewing ability, cohesiveness, adhesive force, adhesiveness and the degree of softness increased. Therefore, using appropriate licorice concentrations, the amount of egg white consumption can be reduced to an acceptable level for mousse. In general, it can be said that using a low-cost source of a native, local, herbal plant, licorice in the formulation of an aerated dairy dessert we can produce a product without having a significant negative impact on the texture from the viewpoint of consumers.