Selection of best conditions of inoculum preparation for optimum performance of the pigment production process by Talaromyces spp. using the Taguchi method

Process optimisation techniques increasingly need to be used early on in research and development of processes for new ingredients. There are different approaches and this article illustrates the main issues at stake with a method that is an industry best practice, the Taguchi method, suggesting a procedure to assess the potential impact of its drawbacks. The Taguchi method has been widely used in various industrial sectors because it minimises the experimental requirements to define an optimum region of operation, which is particularly relevant when minimising variability is a target. However, it also has drawbacks, especially the intricate confoundings generated by the experimental designs used. This work reports a process optimisation of the synthesis of red pigments by a fungal strain, Talaromyces spp. using the Taguchi methodology and proposes an approach to assess from validation trials whether the conclusions can be accepted with confidence. The work focused on optimising the inoculum characteristics, and the studied factors were spore age and concentration, agitation speed and incubation time. It was concluded that spore age was the most important factor for both responses, with optimum results at 5 days old, with the best other conditions being spores concentration, 100,000 (spores/mL); agitation, 200 rpm; and incubation time, 84 h. The interactive effects can be considered negligible and therefore this is an example where a simple experimental design approach was successful in speedily indicating conditions able to increase pigment production by 63% compared to an average choice of settings. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:621–632, 2017     

Designs for restricted exploration in mixture experiments

Extreme Vertices designs were developed by MCLEAN and ANDERSON (1966) for situations where components of a mixture are restricted by lower and upper bounds, SNEE and MARQUARDT (1974) and SNEE (1975) gave algorithms to construct optimum designs in these situations. SAXENA and NIGAM (1975) evolved a transformation which provides designs for restricted exploration using Symmetric Simplex designs. In this paper a procedure has been given which provides alternative designs with uniform exploration in constrained mixture experiments. The procedure is illustrated by an example.     

On the Construction of Balanced and Partially Balanced Ternary Design

A method of constructing balanced and partially balanced ternary designs from balanced and partially balanced incomplete block designs, respectively, and two methods of constructing partially balanced ternary designs from association schemes are obtained. Two new and efficient balanced ternary designs having K < V and R ≦ 20 are obtained by the first method.     

Systematic designs for experiments with mixtures

In this paper systematic designs for experiments with mixtures are developed. The plan of analysis of the experiment is discussed for a quadratic model of SCHEFF É (1958) for q-component mixture with orthogonal polynomials of third degree describing the time trends.