Improved Viscosity of Tomato Fruit Paste and Serum by Genetic Engineering
Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicester, LE12 3RD UK
Received October 10, 1994
Accepted July 28, 1995
Tomato processors aim to produce tomato paste with maximum viscosity. The viscosity of the paste is determined largely by the pectin components of the fruit cell walls. During processing the action of two endogenous hydrolases - pectinmclhyleslerase (PE) and polygalakluronase (PC) - can extensively degrade the pectin and this results in a singificanl reduction in paste viscosity. One approach to reduce this problem is to heat the fruit prior to pulping - the so called "hot break" process. This unactivates endogenous enzymes. With the advent of recombinant DNA techology it is now possible to down regulate enzyme expression in plant tissue. Tomato plants have been genetically engineered with antisense genes to reduce the endogenous levels of both PE and PC. Paste produced from these transgenic fruit has improved serum viscosity and pulp viscosity, respectively.
Presented at the 2nd Croatian Congress of Food Technologists, Biotechnologists and Nutritionists, Zagreb, June15-17,1994