Microalgae degradation follow up by voltammetric electronic tongue, impedance spectroscopy and NMR spectroscopy

Abstract Microalgae play a fundamental role in aquatic primary production and the food chain. They are a recognized source of fatty acids and fatty acid-based lipids of potential interest in the preparation of functional health products, biofuels and renewable chemicals. The exploitation of this bioresource requires a fine monitoring of each production stage. The aim of this work is the microalgae degradation follow up after the concentration stage at the end of the production process by voltammetric electronic tongue, impedance spectroscopy and 1 H NMR spectroscopy. Microalgae samples were allowed to progress along time (from 1 to 23 days). At scheduled selected times, voltammetry, impedance spectroscopy and 1 H NMR measurements were performed. Multivariate analysis was carried out on these data by PLSR. A model calculated in a training set was then applied to a set of validation to predict the time of evolution. For the three techniques good results in prediction for the validation set were obtained (R 2 /RMSEP of 0.961/1.51, 0.956/1.67 and 0.969/1.25 respectively for impedance, voltammetry and NMR spectroscopy). The three techniques were sensitive to the evolution of the microalgae samples. The detection of metabolical changes in the 1 H NMR spectra is also included. This proof of concept could be the basis for future development of rapid and robust strategies for quality control on microalgae production plants.