Energy efficient bead milling of microalgae: Effect of bead size on disintegration and release of proteins and carbohydrates

P.R Postma,E Suarez-Garcia,C Safi,K Yonathan,G Olivieri,M.J Barbosa,R.H Wijffels,M.H.M Eppink

doi:10.1016/j.biortech.2016.11.071

P.R Postma, E Suarez-Garcia + Show 6 more

Open Access

https://doi.org/10.1016/j.biortech.2016.11.071

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Abstract

The disintegration of three industry relevant algae (Chlorella vulgaris, Neochloris oleoabundans and Tetraselmis suecica) was studied in a lab scale bead mill at different bead sizes (0.3–1mm). Cell disintegration, proteins and carbohydrates released into the water phase followed a first order kinetics. The process is selective towards proteins over carbohydrates during early stages of milling. In general, smaller beads led to higher kinetic rates, with a minimum specific energy consumption of ⩽0.47kWhkgDW−1 for 0.3mm beads. After analysis of the stress parameters (stress number and stress intensity), it appears that optimal disintegration and energy usage for all strains occurs in the 0.3–0.4mm range. During the course of bead milling, the native structure of the marker protein Rubisco was retained, confirming the mildness of the disruption process.

Highlights

There is a growing demand for sustainable protein sources and bio-based products as an alternative for traditional agricultural crops
The aim of this work is to investigate the effect of the bead size on the disintegration, release of water soluble components and energy consumption during the bead milling of C. vulgaris, N. oleoabundans and T. suecica
As a follow up to Postma et al (2015), in which a benchmark for the disintegration of C. vulgaris using 1 mm ZrO2 beads was proposed, one goal of this study was to evaluate the effect of decreasing the bead size during bead milling of microalgae

Summary

Introduction

There is a growing demand for sustainable protein sources and bio-based products as an alternative for traditional agricultural crops. Microalgae are a potential source of renewable high value proteins, carbohydrates, lipids and pigments for food, feed and chemical industries (Vanthoor-Koopmans et al, 2013). Such products are typically located intracellular, either in the cytoplasm, in internal organelles or bound to cell membranes, and in most cases, the cells need to be disintegrated before extraction. This step can be done by chemical hydrolysis (Safi et al, 2014), high pressure homogenization (Safi et al, 2014), ultrasonication

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