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Introduction: Beetroot (Beta vulgaris L.) is a good source of dietary fibers, minerals, vitamins, antioxidants, betalains and phenolic compounds. Drying is one of the oldest ways to preserve food and increase its shelf life. Drying with normal methods causes a lot of damage to the flavor and nutrients due to the long time of the drying process and high temperature. Drying with microwave can significantly remove these disadvantages. The use of microwaves in drying significantly reduces the process time and improves the reabsorption and shrinkage characteristics of the product. Foam \mat drying is a new method that takes place in a shorter and faster time than the traditional method of drying with hot air. This method is used to dry liquid or semi-liquid food such as fruit juice and fruit puree or vegetables. The subject of this research is to produce beetroot powder using the foammat method in order to improve the nutritional value and increase the shelf life.Materials and methods: 15 treatments were defined using Design Expert version 11 software and considering three independent variables [maltodextrin (MD), milk protein concerate (MPC], microwave power). The foam produced from maltodextrin and MPC with the same concentration (0-10%) was dissolved in 100 ml of distilled water and then added to 200 g of chopped beet pulp and the mixture and prepared foam was spread in a special tray with a thickness of 1 cm. Drying operation was done in a microwave with power intensity (400-800). Then the produced powder of beetroot was evaluated in terms of some physicochemical characteristics and the responses of the treatments were analyzed by the response surface method (RSM) and the central composite design (CCD) and the optimal sample was obtained.

Introduction: Beetroot (Beta vulgaris L.) is a good source of dietary fibers, minerals, vitamins, antioxidants, betalains and phenolic compounds. Fruits and vegetables are perishable due to their high water content and the presence of nutritious compounds in them, and their storage time is limited. Therefore, in order to preserve them, it is necessary to convert them into more stable products and increase the storage time and also reduce the waste after harvest. It is one of the most valuable products obtained from red beetroot powder, which can be an important component in instant drinks for athletes, a natural color enhancer for nitrite food products or other color substitutes in meat products. Drying is one of the oldest ways to preserve food and increase its shelf life. Drying with normal methods causes a lot of damage to the flavor and nutrients due to the long time of the drying process and high temperature. Drying with microwave can significantly remove these disadvantages. The use of microwaves in drying significantly reduces the process time and improves the reabsorption and shrinkage characteristics of the product. Microwave drying causes homogeneous distribution of heat and enables faster drying, which saves energy and reduces drying time and cost. Microwave assisted floor drying (MFD) for the production of fruit powder. It has high humidity, high viscosity and is sensitive to suitable heat. Foam \mat drying is a new method that takes place in a shorter and faster time than the traditional method of drying with hot air. This method is used to dry liquid or semi-liquid food such as fruit juice and fruit puree or vegetables. The subject of this research is to produce beetroot powder using the foam mat method in order to improve the nutritional value and increase the shelf life. Materials and methods: For this purpose, red beets were washed, peeled, and cut into small cubes. 15 treatments were determined by Design Expert software (version 11), with levels (0-10% w/w) of maltodextrin (MD) and (0-10%) of milk protein concentrate (MPC) to obtain a foam structure. 200 grams of chopped red beets were added to the mixture of malt dextrin, MPC and water. Then, they were mixed completely in a mixer at a speed of 200 rpm for 10 minutes until foam was formed. The beetroot foam was dried in a wide glass container and in a microwave at a power intensity of 400-800 watts. Dried red beetroot powder was ground using a laboratory mill. The powder was packed in zipped polyethylene bags and kept in the refrigerator for further analysis. Based on the achieved responses from the physicochemical tests of the resulting powder, and determining the optimal conditions in terms of the malt dextrin concentration level, MPC and microwave power, the optimal sample was obtained by the response surface method (RSM) and the central composite design (CCD). To prepare control sample, a hot air flasher was installed and dried at a temperature of 70 degrees Celsius. Results and discussion: By increasing the amount of maltodextrin in the foam, the L*, b* index increased (P≤0.05). The range of L* was 21.482-12.21 and the range of b* was 10.44-4.735. By increasing maltodextrin, the mass porosity had a decreasing trend (P≤0.05). Maltodextrin was ineffective on the stability. If the concentration of MPC in the foam increased, the stability, mass porosity, color parameters L*, b* were accordingly increased. The results of the powder evaluation showed that with the increase in the concentration of maltodextrin and MPC, the yield and total phenolic content increased (P ≤ 0.01). Antioxidant capacity in 500 ppm concentration decreased with the increase in the maltodextrin levels and increased with the increase in the concentration of MPC (P ≤ 0.05). The studied treatments had a significant effect on total betalain and its range was 217.676-333.86. The moisture content did not show significant behavior in this research. These two independent variables (MD, MPC) and 400W microwave power had a significant effect on the stability, L*, b* color indexes, porosity, yield, phenolic compounds, and antioxidant capacity of powder. The results showed that the powder with 9.92% maltodextrin and 10% MPC in 400W microwave power can be introduced as the optimal sample. SEM images indicated that the optimal sample has finer particles and smooth, softer and scaly surfaces. FTIR spectrum of optimum and control showed significant similarities. The intensification and displacement of some absorption peaks of the FTIR spectrum pattern confirmed the interaction of the functional groups of amide and carbonyl groups in the control sample, so that the decrease in the number of amide groups was more in the control sample. Conclusion: In the present research, red beetroot powder was obtained using foam mat drying and microwave. Physical properties and microstructure of powder were significantly affected by the influential variables (i.e. MD, MPC and microwave power). Based on the obtained results, the optimal conditions were 10% MD and 10% MPC and microwave power 400 w. The increase in the concentration of MPC led to the enhancement of the apparent porosity and stability of the foam. Also, the increase in MD, MPC and power had a significant effect on color indexes, yield, total phenolic content and antioxidant properties. Betalain showed the best performance in the lowest amount of MD, MPC and power. [ABSTRACT FROM AUTHOR]

In this study, the effect of starter type (probiotic and non-probiotic), milk (58 to 80%), cream (1 to 33%), whey powder (3 to 7%) and milk protein concentrate (6 to 12%) on acidity, pH, viscosity and sensory properties (flavor, color, texture and overall acceptance) of yogurt were evaluated using mixture design and then treatments were clustered and analyzed using two-stage clustering. The results showed that the linear effects of treatments (milk, cream, whey powder and protein concentrate) on all responses of the samples were significant, so increasing milk cream led to an increase in pH, viscosity, texture, color and flavor and overall acceptance and decreased acidity of the samples. Increasing whey powder and milk protein concentrate also led to increasing acidity and decreasing pH, viscosity, texture, color and overall acceptance of the samples. The linear effect of the starter type had no significant effect on the responses of the samples. Two-stage data clustering also divided the treatments of this study into two separate clusters and showed that whey powder and milk protein concentrate are not suitable substitutes for fat.

In this study, the effect of different amounts of skim milk powder (SMP) (5 to 11.5%), milk protein concentrate (MPC) (1 to 5%) and soy flour (0 to 5%) on acidity, pH, viscosity and sensory characteristics (flavor, color and overall acceptance ofconcentrated yogurt were investigated using mixture design. The results of acidity and pH showed that increasing the MPC and SMP decreased the acidity and increased the pH of the sample significantly, while increasing soy flour increased the acidity and decreased the pH of the samples. The results of viscosity showed that only the linear effect of SMP and MPC on the viscosity of samples was significant and increasing of SMP and MPC increased the viscosity of samples but soy flour had non-significant effect on the viscosity of the samples. The results of sensory score also showed that with increasing SMP and MPC, flavor, color and overall acceptance of samples increased significantly, but increasing soy flour decreased the sensory score. The results of variable importance in projection in PLS regression also showed that SMP had the highest positive significance and soy flour had the highest negative significance in terms of pH, viscosity, flavor score, color score and overall acceptance. The optimum formulation was obtained using numerical optimization algorithm in Design Expert software were SMP 9.8%, MPC 1.72% and soy flour 1%. [ABSTRACT FROM AUTHOR]

In this study, the effect of starter type (probiotic and non-probiotic), milk (58 to 80%), cream (1 to 33%), whey powder (3 to 7%) and milk protein concentrate (6 to 12%) on acidity, pH, viscosity and sensory properties (flavor, color, texture and overall acceptance) of yogurt were evaluated using mixture design and then treatments were clustered and analyzed using two-stage clustering. The results showed that the linear effects of treatments (milk, cream, whey powder and protein concentrate) on all responses of the samples were significant, so increasing milk cream led to an increase in pH, viscosity, texture, color and flavor and overall acceptance and decreased acidity of the samples. Increasing whey powder and milk protein concentrate also led to increasing acidity and decreasing pH, viscosity, texture, color and overall acceptance of the samples. The linear effect of the starter type had no significant effect on the responses of the samples. Two-stage data clustering also divided the treatments of this study into two separate clusters and showed that whey powder and milk protein concentrate are not suitable substitutes for fat. [ABSTRACT FROM AUTHOR]