CONICET | Buscador de Institutos y Recursos Humanos

Recent studies have suggested that gamma irradiation (absorbed doses lower than 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 work was to study the effect of gamma irradiation on red beet textural properties. Cylindrical specimens (10-mm length, 15-mm diameter or 10-mm length, 29-mm diameter) were cut, placed in boxes and exposed to gamma irradiation 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. A control batch without irradiation was also considered. Sample texture was evaluated using a universal testing machine and punction (calculated parameter: ratio of the maximum force to deformation), compression (calculated parameter: stress and Hencky strain, sH, at fracture point) and relaxation assays were performed. Force relaxation data were fitted to the Maxwell model. Samples that received 1 kGy-dose showed a higher ratio of the maximum punction force to deformation than control or 2kGy-irradiated samples. This behavior can be correlated with the increase in ferulic acid observed. Stress at failure under compression increased with radiation dose; sH did not showed differences between radiated and control samples. Maxwell modelling of data, which resulted in two elements and a free spring, showed that the residual relaxation force corresponding to the isolated spring, significantly increased with the radiation dose, whereas the percent of the initial relaxation force lost in flow, decreased. All results pointed to a more elastic tissue after gamma irradiation. Results obtained can help in the understanding of the effect of radiation dose on the textural behaviour of red beet, contributing to optimize preservation techniques.

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