Experimental Design of Composites Based on Layered Double Hydroxide, PVP, and PVPP for Craft Beer Clarification

Here we aimed to design, characterize, and optimize the composition of composites with potential application in the clarification of craft beer. Composites were prepared from layered double hydroxide (LDH), polyvinylpyrrolidone (PVP360) and polyvinylpolypyrrolidone (PVPP) through sonication at room temperature followed by filtration, according to a Central Composite Rotatable Design (CCRD). Samples were applied to craft beer at the proper maturation stage, measuring the turbidity of the beverage as an experimental response. Characterization of composites by FTIR and X-ray diffractometry indicated the possibility of hydrogen bonds and an increase in the hydration degree at the interlayer region of LDH, with the absence of intercalation and exfoliation. Surface morphologies observed under SEM and TEM microscopies showed particles with typical features of individual components with good dispersion and apparent interfacial adhesion. Multiple regression analysis yielded a full quadratic model showing the dependence of the response on the composition variables, with a coefficient of determination (R2) of 0.99663. Analysis of variance showed that, except for the LDH*PVP360 interaction, all other coefficients were found to be statistically significant. Response surfaces showed that minimum turbidity (75.89 NTU) was reached for the composite prepared from level 0 of both LDH and PVP360, with PVPP at the +1.682 level, while the turbidity of the untreated sample remained higher than 289. Future perspectives include preparation of nanocomposites through precipitation of LDH in the presence of PVP solution prior to addition of PVPP.