Physical and chemical properties of whipped cream containing Liquorice powder

Whipped cream is one of the cream products that is widely used in confectionary products and is bulked by whipping and incorporating air bubbles. Cream is converted to a foam system by aeration process. The continuous phase is liquid serum and the dispersed phase is air bubbles. Profit formation of a complex foam-emulsion structure of whipped cream to create a desirable texture is dependent on different factors such as whipping conditions, fat content, and presence of stabilizers. A whipped cream with appropriate quality should contain 30-40% milk fat, easily whippable, and produce good foam with high over run. It should also have a long shelf-life and maintain its stability during preservation. Liquorice is one of the oldest pharmaceutical plants, whose active ingredients are used in pharmacy, confectionary, and beverage industries. The most important active ingredient is glycyrrhizic acid which is 50 times sweeter than sucrose. Its root is also an overflowing source of saponin which has different physiochemical properties. Stable foam formation is a property of saponin index. Liquorice saponin can be used in industrial use especially in pharmaceutical, food, and cosmetics industries. The aim of current research is to evaluate physiochemical and rheological properties and textural attributes of whipped cream containing different levels of liquorice powder as an aerating and foaming agent.

Whipped cream was produced from cream with at least 70% fat content, low fat pasteurized milk with 1.5% fat content, milk protein concentrate with 70% protein content, vanilla, sucrose, and different levels of liquorice powder (2, 4, 6, and 8%). Whipping time, acidity, pH, over run, and syneresis of final products were evaluated. Rheological properties were studied at 40C and at shear rate 0-100 S-1. Textural attributes were evaluated using back extrusion with a cylindrical probe (38 mm diameter) and penetration rate 1 mm/s and penetration depth 30 mm.

Whipping time increased with elevation of liquorice percentage in whipped cream formulation, which is due to presence of stabilizers which can both increase the viscosity of liquid phase and prevent foaming properties of milk proteins from protein-stabilizer interactions. The highest over run belonged to 4% treatment while the lowest magnitude was reported for 8% sample. Over run quantity is dependent on different factors such as mixture ingredients including fat content, solid materials, sweeteners, and presence of stabilizers. Due to presence of saponin in liquorice, it can be concluded that elevation of over run in samples containing liquorice up to 4% is probably because of foaming ability of saponins. From literature review, it has been reported that with the rise in gum concentration (gum in liquorice), over run decreases in the foam system. Generally, with further increase in viscosity of the liquid phase with the growth of gum concentration, air bubbles cannot be introduced to the system through aeration process. Hence, the descending trend in over run of samples containing 6 and 8% liquorice is probably due to higher viscosity of the whipped cream. Acidity content of samples also increased. Acidity increment in whipped cream samples with liquorice rise is probably due to the acidic nature of saponins in liquorice powder. PH was reduced significantly with an increase in liquorice amount in the formulation a growth in acidity. Saponins present in the extract can produce acidic properties to some extent. The highest extent of syneresis in different samples was reported for 6% while the lowest amount was for 2%. Syneresis in confectionary cream shows emulsion rupture and has a close relationship with product viscosity. So it can be expected that higher viscosity in whipped cream results in less syneresis in the final product. According to the results of the current research, syneresis value in 2% was lower compared to control sample, which is probably due to the increase in viscosity of the whipped cream. With elevation of liquorice, syneresis increased compared to the control sample. As indicated, liquorice root has gum and gums increase the viscosity of the final product, thereby reducing syneresis by absorbing water and incorporating it in the gelly network. Power law model was selected for predicting rheological properties of samples. The results suggested that flow index behavior was less than 1 in all samples indicating non-Newtonian, pesudoplastic behavior. Apparent viscosity versus shear rate showed shear thinning behavior, which indicated that the apparent viscosity diminished with increase in the shear rate. Gums have shear thinning behavior, so regarding the presence of gum in liquorice and augmented liquorice percentage, more deviation from Newtonian state was observed. Textural analysis indicated that hardness, adhesiveness, and adhesive force had an ascending trend with increase in liquorice percentage except for 4% sample. Totally, it can be concluded that a desirable product with higher over run and profit texture can be obtained using liquorice powder as a natural, native, local plant product in whipped cream formulation with pharmaceutical properties which can be potentially useful for the health of consumers.