The impact of E-beam treatment on the microbial population and sensory quality of hard annatto-coloured cheese

Abstract

The effects of E-beam radiation on microbiota, colour, texture and sensorial properties of hard annatto-coloured cheese during storage at 4 and 14 °C were studied. Doses of up to 2 kGy provoked a decrease in the total bacterial number, although microbiota recovery to initial levels during storage, even under refrigeration temperature, was observed. However, a higher temperature (14 °C) was required to detect bacterial growth in cheese treated at 3 kGy. Moreover, the effects of the dose on the hardness, springiness, cohesiveness and colour parameters were interdependent of the storage conditions. According to the combined effects of E-beam treatment and storage conditions, multivariate cluster analysis allowed treated cheeses irradiated at 0–1 kGy (cluster 1) to be distinguished from those irradiated at 2–3 kGy (cluster 2), which were stored at 4 °C for 28 days. Cluster 3 included irradiated cheeses (1–3 kGy) stored at a higher temperature (14 °C). Although off-odour and off-flavours arose immediately after treatment, they disappeared progressively during storage at doses lower than 2 kGy. Nevertheless, consumers could detect changes in the colour derived from the radiation at 2 kGy, however, those changes may be unimportant because of the wide colour ranges of commercial annatto-coloured cheeses.