Effect of triglycerides on gelatinisation and rheological properties of concentrated potato starch preparations

The effect of triglycerides on gelatinisation and rheological properties of potato starch was studied by calorimetric and rheological measurements, microscopy and electron spin resonance. Samples contained 45 or 48% water (w/w, wb) and the lipid content ranged from 0 to 20% (g/100 g starch–water). The addition of triglycerides had no effect on gelatinisation process and rheological behaviour of starch during heating. Triolein seems to form a separated dispersed phase in the system which does not prevent the hydration and swelling of starch granules and the melting of ordered regions, in our studied conditions. A lower value of the storage modulus (G′) of starch preparations at ambient temperature was detected in the presence of triglycerides. Shortenings could diminish bread firmness by a lubricant effect, without modifying retrogradation of starch. Triglycerides do not influence the changes in the water distribution during thermal treatment in the starch system. This behaviour has implications for the use of fat replacers in bakery products with a reduced fat content.