The effect of different particle size reduction techniques on the biomass microstructure and the influence on the pectin extraction yield and structure

Abstract

Particle size is known to be an influential parameter during pectin extraction, and a decreased particle size was already linked to an increased extraction efficiency. Particle size reduction can be achieved through different fracture mechanisms and this study investigated the effect of different particle size reduction techniques on the pectin extraction yield and structural characteristics. Three biomasses with an increasingly complex composition, being carrot pomace, broccoli stems and pumpkin pomace, were included in this study. For all three biomasses, high shear mixing, high pressure homogenization (HPH) and ball milling (BM) resulted in a significant decrease of the median particle diameter. After HPH and BM, samples with a comparable particle size distribution, but different microstructure, were obtained. After acid pectin extraction performed on these samples, a comparable and significantly higher extraction yield, compared to the non-treated sample, was obtained, indicating that particle size reduction resulted in an increased extraction efficiency. Yet, the fracture mechanism did not have a substantial influence. Overall, the different particle size reduction techniques had no clear impact on the structural characteristics of the extracted pectin, and the main difference between the different biomasses was the extent of protein and starch co-extraction during the pectin extraction process.