Multiparametric investigation of mould-free shelf life of bread via factorial design

The investigation of a complex process, such as the bread making process, c an be greatly favored by the approach of statistical design of experiments. Using simple first order factorial designs, reliable models were construct ed investigating the effects of salt, sugar, sorbic acid, calcium propionat e, vegetable fibers, fat and emulsifier on the shelf life of bread (optimiz ation parameter). These effects were in general linear. An exception was ob served in the case of use of calcium propionate where an interaction betwee n salt and sugar was determined. The effects of all significant factors on optimization parameter were reasonable. Sorbic acid and calcium propionate proved to be more effective preservatives than salt and sugar by an order o f magnitude. Antifungal efficiency of sorbic acid was found to be about thr ee times that of calcium propionate. Prolongation of shelf life reached 117 % for sorbic acid and 63 % for calcium propionate, when salt and sugar were fixed to their basic levels. Vegetable fibers had a detrimental effect on shelf life greatly decreasing it by as much as 65 % of the control samples (without fibers). Addition of fat and emulsifier in the dough showed a slig htly negative effect on the mould-free shelf life of bread.