Development of a lactic casein based savoury flavour product : a thesis presented in partial fulfilment of the requirement for the degree of Master in Food Technology at Massey University, Manawatū, New Zealand

Abstract

The aim of this project was to develop a casein-based hydrolysate formulation that has higher savoury flavour and is more cost effective than an existing commercial savoury hydrolysate. From the literature review, bovine casein protein has the most savoury flavour potential of all proteins due to its high glutamic acid and glutamine content. The symbol of savoury flavour is cheese which is made from casein protein in the western world. The main reaction resulting in cheese savoury flavour development is proteolysis where casein protein breaks down to peptides by protease and free amino acids by peptidases. Two different systems were designed to be based on those reactions in order to generate maximum free glutamic acid during the experiments. The enzyme substrate was a 10% lactic sodium caseinate slurry, which is the foundation of the experiments. With the first system, an enzyme preparation with protease functions was added first and followed by an enzyme preparation with peptidase functions. With the second system only one enzyme preparation with both protease and peptidase activity was added for each trial. From the results, it was found that none of the enzyme combinations from either system were able to achieve the same amount of free glutamic acid as the existing commercial product (31.95 mg/g of protein) within 24 hours. However, multiple options would have had equivalent free glutamic acid if the free glutamine content could be converted to L-glutamic acid using a glutaminase. Flavorzyme 1000L from system one was selected to be the option combining with glutaminase based on its cost, microbiology and chemistry process results. Two different dosages (0.25% and 0.5%) of Glutaminase C100SD were trialled with 2% of Flavorzyme 1000L. From the degree of hydrolysis, free amino acid content, molecular weight profile and residual glutamine results, there were almost no difference between the two trials. The final formulation of Flavorzyme 2% and 0.25% Glutaminase C100SD had 48% more free glutamic acid than the existing commercial control. It also achieved a 33% ingredient cost reduction. Most importantly, the final formulation resulted in a 22.5% final ingredient cost reduction per kilogram based on the same commercial cost model as the control. An informal sensory panel indicated that the new savoury hydrolysate was more savoury and less bitter than the existing commercial control.