Effect of gamma irradiation on red beet (Beta vulgaris l. var. conditiva) textural properties

LATORRE M.E; NARVÁIZ P; ROJAS A.M.; GERSCHENSON L.N.

ANAHEIM, CALIFORNIA, USA.

Congreso; IFT 2009 ANNUAL MEETING + FOOD EXPO; 2009

Institute of Food Technologists

Recent studies have suggested that gamma irradiation (absorbed doses lower then 3 kGy) is one of several “hurdles” that can be used in fruit and vegetable processing. Red beet (Beta vulgaris L. var. conditiva) is a popular item present in ready to eat salads and minimally processed foods. Being texture a major attribute of food quality, the aim of this research is the study of the effect of gamma radiation on red beet textural properties. Cylindrical specimens (10mm length, 15mm diameter or 10mm length, 29mm diameter) were placed in boxes and  were exposed to gamma radiation from a 600,000 Ci  Cobalt 60 source (Semi-industrial facility, Ezeiza Atomic Center, Argentina) at 25ºC, receiving doses of 1.00 and 2.00 kGy. Sample texture was evaluated using a universal testing machine and performing punction (parameter evaluated: ratio of the maximum force to deformation), compression (parameters evaluated: stress and Hencky strain, eH al fracture point) and relaxation assays. These last data were fitted to a Maxwell model consisting of two elements and a free spring. The sample that received a dose of 1 kGy showed a higher ratio of the maximum force to the deformation than the control or the 2kGy-irradiated sample. This behaviour can be correlated with the increase in ferulic acid observed. Stress at compression increased with radiation doses; eH did not showed differences between irradiated and non irradiated samples. Relaxation data modelling showed that the constant of the spring for the first Maxwell’s element, as well as the one of the free spring, increased significantly as radiation doses increased. In general, results obtained pointed to a more elastic behaviour for gamma irradiated samples. Results obtained can help in the understanding of the effect of radiation doses on the textural behaviour of red beet, helping in the optimization of a combined preservation technique.