Food Technology
Delaram Hami; Mohammad Goli
Abstract
Introduction: Ice cream contains a mixture of milk components, sweeteners, stabilizers, emulsifiers, and flavorings. The quality of the finished product depends not only on the processing conditions or the freezing efficiency, but also on the constituents, the amount of entrapped air, and the number ...
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Introduction: Ice cream contains a mixture of milk components, sweeteners, stabilizers, emulsifiers, and flavorings. The quality of the finished product depends not only on the processing conditions or the freezing efficiency, but also on the constituents, the amount of entrapped air, and the number of ice crystals. The physical structure of ice cream has a significant effect on the melting properties (melting rate) and texture (hardness) of ice cream (Mouse & Hartel, 2004). The improvement and expansion of the ice cream structure are attributed to the macromolecules present in the ice cream mixture; milk fat, protein, and carbohydrates (Adapa et al., 2000). Quinoa as a high biologically valuable protein can be used in various food products to enrich and positively affect the physical and sensory properties of the product (James, 2009). The purpose of the present study was to replace skim milk powder with quinoa flour (0 to 100%), hydrogenated vegetable oil (4.5 to 8.5%) and Panisol gum (0.25 to 0.65%) to obtain the optimal formulas of Vanilla ice cream using the response surface methodology. Materials and Methods: After adjusting the ratio of the ingredients in the various ice cream formulations, the amount of raw material of each formula was weighed. The milk was then heated to about 45 ° C, and then the remaining ingredients were slowly added and thoroughly mixed. The mixture was then pasteurized at 85 °C for 15 minutes. After the pasteurization operation, the mixture was immediately kept in a water-ice bath and cold down for 4 hours in a 4 °C refrigerator. After the ripening step, the mixture went through the freezing phase in a homemade ice cream maker. The ice cream samples were packed in plastic containers and stored at -18 °C for the period of hardening. To optimize the process conditions, the independent variables A (quinoa flour replacement from 0 to 100%), B (hydrogenated vegetable oil from 4.5 to 8.5%) and C (Panisol gum from 0.25 to 0.65%) were selected at five levels. To obtain optimal points, 34 experiments were recommended by design expert software. The volumetric overrun (%) and the melting rate (g/min.) were measured according to Hashemi et al., (2015) method. Ice cream textural properties were tested after 3 days storage at -18 °C using a Brookfield texture analyzer. It was equipped with a cylindrical probe with a diameter of 6 mm and a height of 15 mm. The probe was applied to the test samples twice at a speed of 1 mm / s and up to 50% of the probe height and the results were recorded by device software. Ice cream textural data used in this study included hardness (g) and adhesiveness (g. sec) (Hashemi et al., 2015). Results and Discussions: Reducing overrun of ice cream samples by increasing the replacement levels of quinoa flour can be attributed to an increase in the viscosity. As viscosity increases, due to the reduced mixing ability of the ice cream mixture, the ability of air to enter the mixture of ice cream containing quinoa flour has been reduced during freezing (Gelroth et al., 2001). The reason for the decrease in the melting rate of ice cream with increasing percentage of quinoa flour replacement can be attributed to the existence of polysaccharide compounds with high water holding capacity, which led to increase the product water intake intensity and viscosity and subsequently decreasethe overrun. One of the factors affecting the melting properties is the increase in volume. In addition, the role of quinoa flour in enhancing the melting resistance of ice cream can be attributed to the type of protein content, the emulsifier potential and the surface active properties of its proteins and lipids. The presence of high amounts of protein in quinoa flour has a significant effect on the stability of air molecules. Since quinoa flour contains high amounts of protein, this fraction of flour quinoa protein, increases the hardness of ice cream through creating hydrogen bonds between the amide-hydroxyl and hydroxyl-carbonyl groups with other polar groups of other ice cream components such as panisol gum. In addition, hydrogen bonds are likely to be formed by electrostatic interactions between the quinoa protein groups of the polar with the polar part of the gum panisol, which may also be the reason for the increased hardness of the ice cream in the presence of the quinoa flour. With polar groups, quinoa flour traps the water in its structure and ultimately increases the consistency and adhesiveness of the ice cream. It is also possible that the protein portion of quinoa flour binds to the water molecules present in the sample through hydrogen bonding and ion-dipole and dipole-dipole interactions, thereby reducing water activity, increasing sample adhesiveness (Fatemi, 2008). The optimal formulas were predicted for replacement of skim milk powder with quinoa flour at 25 and 53%, hydrogenated vegetable oil 8.5 and 8.2% and panisol gum 0.39 and 0.48%, respectively.
Zahra Hoseinpour; Hojjat Karazhiyan
Abstract
Introduction: 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 ...
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Introduction: 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. Matrials and methods: 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. Results and discussion: 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.
