A Multiscale Study of Powder Reconstitution Phenomena

Executive summary until October 2021 – year 3
(PhD duration: 1st February 2019 – 31th January 2022)
The first year of the PhD work dealt with the systematic physicochemical analysis of powders and their classification according to their reconstitutability. It was achieved at the end of January 2020 with the following deliverables:
(1) Powder classification according to their reconstitution behavior;
(2) First statistical correlations between the various powder characteristics and their wettability and reconstitutability.
Paper I has been published in Powder Technology and is related to year 1 deliverables. https://doi.org/10.1016/j.powtec.2021.01.056.
The second year of the PhD work was focused on a powder presenting a low wettability (i.e. whey protein powder), which was coated with sugars to improve its wetting behavior. In agreement with IFPRI partners, five sugars (i.e. sucrose, lactose, glucose, fructose, and galactose) were chosen for their wide range of physicochemical properties: solubility, chain length, structure, glass transition temperature, hydrophilicity, etc. Links between powder wetting and sugar nature, surface modification, quantity, and coating depth were thoroughly investigated. The deliverables were achieved at the end of July 2021:
(1) Surface chemical mapping and nanoindentation to establish correlations with powder wettability;
(2) Effect of surface modifiers (quantities to cover the surface, distribution at the particle surface, minimal quantity necessary to improve wetting, etc.).
This part, focused on AFM, will be continued during the 4th year of IFPRI project (Feb. 22 – Feb. 23) by a post doc or a technician working on the project.
The third year of the PhD work was dedicated to modelling. On one hand, a new approach of descriptive modelling of food powders reconstitution kinetics followed by granulometry was investigated. The developed model allows to describe the different reconstitution steps by successive first-order indicial responses, thus allowing to calculate characteristic times and rates of each step. On the other hand, it was tried to develop a predictive model for reconstitution times in reconstitution conditions employed in year 1 based on physicochemical properties of powder characterized in year 1. The deliverables were achieved in November 2021:
(1) Fitting of reconstitution kinetics followed by granulometry;
(2) Empirical models able to predict reconstitution times from powder physicochemical characteristics.
Paper II related to year 3 deliverables is under correction and will be submitted soon.