FermentYeast

: otimização das condições de propagação de leveduras cervejeiras

Abstract

Brewer’s yeast are Saccharomyces genus and they need some requirements to be propagated effectively, in order to obtain the maximum concentration of yeast capable of generating high yields. Factors such as temperature, concentration of nitrogen and glucose, aeration and agitation are the main factors contributing to an increased concentration of yeast. For the studies we used three ale yeasts such as Saccharomyces cerevisiae 1762: Belgian Abbey II TM, Saccharomyces cerevisiae 1084: Irish Ale TM and Saccharomyces cerevisiae 3068: Weihenstephan WeizenTM and a lager yeast type, Saccharomyces pastorianus 2308: Munich LagerTM. The yeasts that are commonly used in the brewing industry, bakery and bioethanol production, are normally bought lyophilized. The lyophilization process cause yeast viability drop, and consequently there is a decrease in final product yields. Thus, the project FermentYeast: Optimization of propagation conditions for brewing yeasts is mainly to optimize the maximum growth rate (μmáx.) and to find the optimum concentration of Corn Steep Liquor (CSL inexpensive supplement) and temperature. Aeration and agitation were also later studied factors. The optimal conditions of propagation depends mainly on the yeast strain so, this process of optimization is unique for every yeast. The yeast Saccharomyces pastorianus 2308: Munich LagerTM presented optimal temperature values of 27 ⁰ C and optimal CSL concentration of 16.20 g /L. The yeast Saccharomyces cerevisiae 1762: Belgian Abbey II TM, Saccharomyces cerevisiae 1084: Irish Ale TM and Saccharomyces cerevisiae 3068: Weihenstephan WeizenTM showed optimum values of temperature of 30 ° C and optimal concentration of CSL of 15.84, 13.30 and 20,00 g /L. The flow rate of 6 l / h gave more efficient growth to Saccharomyces cerevisiae 3068: Weihenstephan WeizenTM and Saccharomyces pastorianus 2308: Munich LagerTM.

Date of Award	26 May 2014
Original language	Portuguese
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Fernando Filipe Macieira da Silva (Supervisor) & Isabel Vasconcelos (Supervisor)