Ultrasound-assisted starch hydrolyzing by alpha-amylase: Implementation of computational fluid dynamics, acoustic field determination, and rheology modeling.

The study aimed to optimize the ultrasonic-assisted modification (UAM) of corn and potato starch by assessing the influence of ultrasound geometry, power, and frequency on the fluid flow for sonicated starch to achieve porous starch with a higher degree of hydrolyzing by α-amylase. This assessment was conducted through mathematical modeling and 3D computational fluid dynamics (CFD) simulations. The ultrasonic pressure field is determined by the solution of the non-linear Westervelt equation in the frequency domain. Then, the obtained field is utilized to simulate the dissipated power and flow field characteristics. According to the results obtained from the Rapid Visco Analyzer (RVA), it was observed that the peak and final viscosity of hydrolyzed sonicated starch were less than hydrolyzed native starch. This decrease in viscosity indicates a breakdown of the starch structure, leading to a more fluid-like consistency. The shear rate and shear stress data are used for rheology modeling. The fluid's viscosity is represented based on three models of Herschel-Bulkley, Casson, and Power law (Ostwald-de Waele). The magnitude of yield shear stress at low shear rates, the shear-thinning behavior, and the nearly Newtonian fluid nature at high shear rates are extracted from the viscosity models. The surfaces of the starch granules were analyzed using scanning electron microscopy (SEM) revealed that sonication treatments caused damage, cracks, and porosity on the surfaces of the starch granules which were prone to amylolytic enzymes. This indicates that the structural integrity of the granules was compromised and facilitated enzyme penetration. This study proposes that ultrasonication can be utilized to produce damaged starch, which is susceptible to hydrolysis by α-amylase. This approach holds the potential for reducing enzyme consumption in various industries.

Effective mitigation in the amount of acrylamide through enzymatic approaches.

Acrylamide (AA), as a food-borne toxicant, is created at some stages of thermal processing in the starchy food through Maillard reaction, fatty food via acrolein route, and proteinous food using free amino acids pathway. Maillard reaction obviously takes place in thermal-based products, being responsible for specific sensory attributes; AA formation, thereby, is unavoidable during the thermal processing. Additionally, AA can naturally occur in soil and water supply. In order to reduce the levels of acrylamide in cooked foods, mitigation techniques can be separated into three different types. Firstly, starting materials low in acrylamide precursors can be used to reduce the acrylamide in the final product. Secondly, process conditions may be modified in order to decrease the amount of acrylamide formation. Thirdly, post-process intervention could be used to reduce acrylamide. Conventional or emerging mitigation techniques might negatively influence the pleasant features of heated foods. The current study summarizes the effect of enzymatic reaction induced by asparaginase, glucose oxidase, acrylamidase, phytase, amylase, and protease to possibly inhibit AA formation or progressively hydrolyze formed AA. Not only enzyme-assisted AA reduction could dramatically maintain bio-active compounds, but also no damaging impact has been reported on the sensorial and rheological properties of the final heated products. The enzyme engineering can be applied to ameliorate enzyme functionality through altering the amino acid sequence like site-specific mutagenesis and directed evolution, chemical modifications by covalent conjugation of L-asparaginase onto soluble/insoluble biocompatible polymers and immobilization. Moreover, it would be possible to improve the enzyme's physical, chemical, and thermal stability, recyclability and prevent enzyme overuse by applying engineered ones. In spite of enzymes' cost-effective and eco-friendly, promoting their large-scale usages for AA reduction in food application and AA bioremediation in wastewater and soil resources.