Effect of freezing rates on α-amylase enzymatic susceptibility, in vitro digestibility, and technological properties of starch microparticles.

The aim of this study was to evaluate the effect of freezing rates using direct (LF: Liquid nitrogen) and indirect (RF: Cryogenic refrigerator and UF: ultra-freezer) methods at temperatures of (-20, -80, and - 196 °C) on the enzymatic susceptibility with α-amylase for microparticles. In vitro digestibility parameters and technological properties were also analyzed. Lower rates resulted in larger ice crystals, damaging the starch structure. Hydrolysis was more pronounced at slower rates RF: 0.07 °C/min and UF: 0.14 °C/min, yielding maximum values of RDS: 37.63% and SDS: 59.32% for RF. Type A crystallinity remained unchanged, with only a noted increase in crystallinity of up to 6.50% for FR. Starch pastes were classified as pseudoplastic, with RF exhibiting superior textural parameters and apparent viscosity. (RF: 7.18 J g-1 and UF: 7.34 J g-1) also showed lower values of gelatinization enthalpy. Freezing techniques were viable in facilitating the diffusion of α-amylase and reducing RS by up to 81%.

Enzyme immobilization technology as a tool to innovate in the production of biofuels: A special review of the Cross-Linked Enzyme Aggregates (CLEAs) strategy.

This review emphasizes the crucial role of enzyme immobilization technology in advancing the production of two main biofuels, ethanol and biodiesel, with a specific focus on the Cross-linked Enzyme Aggregates (CLEAs) strategy. This method of immobilization has gained attention due to its simplicity and affordability, as it does not initially require a solid support. CLEAs synthesis protocol includes two steps: enzyme precipitation and cross-linking of aggregates using bifunctional agents. We conducted a thorough search for papers detailing the synthesis of CLEAs utilizing amylases, cellulases, and hemicellulases. These key enzymes are involved in breaking down starch or lignocellulosic materials to produce ethanol, both in first and second-generation processes. CLEAs of lipases were included as these enzymes play a crucial role in the enzymatic process of biodiesel production. However, when dealing with large or diverse substrates such as lignocellulosic materials for ethanol production and oils/fats for biodiesel production, the use of individual enzymes may not be the most efficient method. Instead, a system that utilizes a blend of enzymes may prove to be more effective. To innovate in the production of biofuels (ethanol and biodiesel), enzyme co-immobilization using different enzyme species to produce Combi-CLEAs is a promising trend.