Use of gamma radiation in sheep butter manufacturing process for shelf-life extension

Gamma-irradiated sheep cream (1 kGy) was used to produce butter that was analysed during refrigerated storage up to 90 days in shelf-life extension studies including sensory, microbiological and water content assessments. The water content of the sheep butter made with irradiated fermented cream was 10% higher than that of control butter. A slower increase in bacterial load during storage was detected for the butter manufactured with irradiated fermented sheep cream compared with control butter; however, fungi increased at similar rates in both cream-irradiated and control butters during storage. The sensory evaluation suggested, in general, the acceptance of the irradiated samples by the panellists. The microbiocidal potential of gamma radiation of fermented sheep cream was highlighted, but was not reflected in extension of shelf-life of the butter produced. The traditional manufacturing process itself was found to be a major vehicle for microbial contamination of this dairy product, preventing its shelf-life extension.