The Influence of Heat Processing and Mechanical Disintegration on Yeast for Single-Cell Protein

Yeast was processed by means of different technical drying procedures, heating in water suspension, and mechanical disintegration. The influence on the ultrastructure, the nutritive value and on the availability of the cell nitrogen-containing compounds to chemical extractants was studied. On micrographs no cell wall disrupture could be observed after any of the heat treatments. The internal cell structure was affected at the higher temperatures. After drum drying this structure was destroyed to a large extent. The heat treatments increased the nutritive value compared to unheated yeast cells but did not increase the availability of the cell content to chemical extractants. Mechanical disintegration increased both the nutritive value and the availability to chemical extractants. Heat processes and mechanical disintegration give high nutritive value to the yeast. Mechanical disintegration is advantageous when processing steps such as extraction with chemicals are necessary for obtaining specific protein products.