Distiller's dried grains and garbanzo flour were blended with corn grits for the development of extruded snacks using a single screw extruder. Distiller's dried grains were processed for food application and termed as food grade distiller's dried grains or FDDG. Effects of different level of FDDG addition (0%–20%) and extrusion process parameters such as barrel and die temperature (100–140°C), screw speed (100–200 rpm), and feed moisture content (14%–20% wet basis) on the physical properties (expansion ratio, bulk density, color parameters), functional properties (water absorption and solubility indices), and nutritional properties (total dietary fiber, soluble and insoluble dietary fiber and protein content) of the extrudates were investigated and optimized using response surface methodology. FDDG incorporation had a significant effect (p < 0.05) on the total dietary fiber, color parameters, water solubility, and water absorption indices of the extruded snacks. Desirable expanded extrudates with a high level of total dietary fiber and protein were obtained with blends containing 20% FDDG extruded at 140°C extrusion temperature, 167 rpm screw speed, and 19% feed moisture content. Results indicate garbanzo flour, and FDDG can be successfully blended with corn grits to produce nutritious gluten‐free extruded snacks which are high in protein and dietary fiber.
A combination of different levels of distillers dried grains processed for food application (FDDG), garbanzo flour and corn grits were chosen as a source of high‐protein and high‐fiber extruded snacks. A four‐factor central composite rotatable design was adopted to study the effect of FDDG level, moisture content of blends, extrusion temperature, and screw speed on the apparent viscosity, mass flow rate or MFR, torque, and specific mechanical energy or SME during the extrusion process. With increase in the extrusion temperature from 100 to 140°C, apparent viscosity, specific mechanical energy, and torque value decreased. Increase in FDDG level resulted in increase in apparent viscosity, SME and torque. FDDG had no significant effect (p > .5) on mass flow rate. SME also increased with increase in the screw speed which could be due to the higher shear rates at higher screw speeds. Screw speed and moisture content had significant negative effect (p < .05) on the torque. The apparent viscosity of dough inside the extruder and the system parameters were affected by the processing conditions. This study will be useful for control of extrusion process of blends containing these ingredients for the development of high‐protein high‐fiber extruded snacks.
Hydrodynamic cavitation (HC) is a process in which high energy is released in a flowing liquid upon bubble implosion due to decrease and subsequent increase in local pressure. While cavitation has been a serious problem in a hydraulic system, its energy can be harnessed for various physical and chemical processes. Food and beverage industries have been utilizing the principle of HC as a tool to homogenize, pasteurize, break, or mix food macromolecules. In this review article, the principle, design aspects, and different application of hydrodynamic cavitators in food and beverage processing are described in details. Advantages over acoustic cavitation, comparative studies, and future prospects of HC in food and beverage industries are also discussed.
Practical ApplicationsIn this fast-developing world, food industries are thriving to adopt energy efficient advanced technologies. Hydrodynamic cavitators are popular in dairy research facilities and industries. Hydrodynamic cavitation has the advantages in lowering the capital cost, reducing production time, enhancing production efficiency, and food safety while preserving the quality of the food product. Hydrodynamic cavitators can be utilized for the purpose of extraction, emulsification, sterilization, and homogenization. Large-scale application of hydrodynamic cavitators is still not common and there is scope for its applications in different food and beverage industries.
The nutritional profile of apple pomace and soy makes them ideal for development of a new extruded snack food with health benefits. Understanding how blend of apple pomace, defatted soy flour, and corn grits behave under different process conditions during extrusion will help in formulating the extrusion process. Experimental design with apple pomace level (0–20%), barrel and die temperature (100–140 °C), screw speed (100–200 rpm), and moisture content of blend (14–20% wet basis) as independent variables produced 27 different combinations that were studied using response surface methodology to investigate the effect of these variables on system parameters (apparent viscosity, mass flow rate, torque, die pressure, dough temperature, and SME). As the temperature profile increased, apparent viscosity, die pressure and specific mechanical energy decreased. Increase in apple pomace level resulted in significant (p < .05) decrease in apparent viscosity, SME, and torque, and significant (p < .05) increase in the mass flow rate. Response surface regression models were established to correlate the system parameters to the process variables. The data obtained from the study could be used for control of extrusion process of blends containing the aforementioned ingredients.
Practical applications
During extrusion process, the shearing effect of screws along with thermal energy and other extruding conditions modifies the rheological, physical and chemical properties of the raw materials. Investigating the changes in system parameters will provide better insight into understanding such modifications. In this study, we have chosen raw materials that are high in protein and fiber, and the effect of extrusion processing on the system parameters such as viscosity, SME, MFR, and torque was evaluated. The study provides new experimental data of system parameters of apple pomace‐soy flour‐corn grits dough during single screw extrusion. The results obtained will be of great significance for formulation and development of snacks using the above mentioned raw materials.
Response surface methodology was used to investigate the single screw extrusion of apple pomace-defatted soy flour-corn grits blends and the product properties. Five different blends at a level of 0-20% w/w apple pomace were extrusion cooked with varied barrel and die temperature (100-140℃), screw speed (100-200 rpm), and feed moisture content (14-20% wet basis). Increasing apple pomace content in the blends significantly ( P < 0.05) increased the bulk density, the total phenolic content, and the antioxidant activity of the extrudates. The expansion ratio increased with pomace inclusion level of 5% but decreased significantly ( P < 0.05) at higher levels of pomace inclusion (10-20%). Moisture content had quadratic influence on water absorption and solubility indices. Optimal extrusion cooking conditions most likely to produce apple pomace-enriched extruded snack products were at 140℃ barrel and die temperature, 20% feed moisture content, and 200 rpm screw speed. The results indicated active interaction between apple pomace and starch during expansion process.
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