Effect of high pressure homogenization on the production of yeast extract via autolysis and beta-glucan recovery

Abstract

The aim of this study was to assess the application of high pressure homogenization (HPH) as a pretreatment prior to the process of autolysis of Saccharomyces cerevisiae cells in order to enhance both the production of yeast extract and the valorization of the solid residue of autolysis for β-glucan extraction. Autolysis of HPH treated (200–600 bar, 1–3 passes) and untreated samples, carried out at 52 °C and pH = 5.5, was mathematically modelled based on protein, amino acid and total solids release. HPH treatment accelerated yeast autolysis at all conditions studied and resulted in higher protein, amino acid and total solids yield. A combination of HPH treatment and shorter autolysis times achieved high extract yields of low turbidity. The β-glucan content of the solid autolysis residue increased with increasing treatment intensity and autolysis time with a simultaneous decrease in protein content due to the mechanical disruption of the cells. Industrial relevanceThe use of HPH as a pretreatment of yeast suspensions allows for the acceleration of yeast extract production by autolysis, reducing the very long autolysis times otherwise required. At the same time, the solid residue obtained after autolysis has a higher β-glucan content for HPH treated samples, allowing for more efficient valorization of this rich in valuable glucan by-product. In our work we have demonstrated that with one pretreatment step, both aspects of the autolytic process can be significantly enhanced.