| Abstract: | Present-day economic pressures stimulate technological innovations toward more rapid processing and to minimise both capital and production costs. Fermentation and maturation practices in most production plants are essentially unchanged from the low productivity batch processes. In terms of process economics two alternatives exist—moving to greater volume accelerated-batch processing and applying fully continuous high rate fermentation systems. Central to these issues are the growth controlling aspects of yeast performance in brewery fermentations. The importance of dissolved oxygen on lipid metabolism, yeast growth and beer flavour, the precise role of storage carbohydrates and the critical nature of the glycolytic/gluconeogenic junction in controlling fermentation performance are reviewed. The objectives of process optimisation are to build up sufficient yeast concentrations to gain optimal rate and extent of attenuation and desired flavour development whilst balancing but not over-expending wort nutrients for growth and maintenance. In this regard great promise may lie with new technologies including yeast oxygenation and immobilised cell systems. Particular emphasis is placed upon the ways in which this may be technically achieved and attention is drawn to the complexity of innovation management. Practical implications of factors benefiting and adversely affecting fermentation efficiency and beer flavour in both traditional and continuous immobilised cell systems are discussed. |
