Effect of gamma radiation on the microbiological and physicochemical parameters and on the phenolic compounds of a fruit residue flour during storage

Abstract

Agroindustrial residues have high levels of nutrients, but are little exploited for consumption because they require prior treatment to ensure microbiological safety. Irradiation is an effective process for the reduction of microbial counts with maintenance of the product characteristics. The objective of this study was to evaluate the effect of irradiation on the microbiological quality, physicochemical properties and phenolic compounds of a fruit residue flour during storage. The flour was obtained from dehydrated residues of pineapple, melon, papaya and apple, which were submitted to irradiation doses of (0, 1, 2 and 3 kGy). The microbiological (coliforms, moulds, yeast and Salmonella sp. counts) and physicochemical (pH, titratable acidity, soluble solids, water activity, colour parameters L*, a* and b* and phenolic compounds) parameters were evaluated after 0, 7, 14 and 21 days of storage. All the irradiation treatments reduced the microbial count, and the presence of Salmonella sp was not detected in any of the samples. The acidity and pH showed changes during storage. The soluble solids and water activity showed no significant differences between the doses during storage. The phenolic compounds were preserved by the application of irradiation. The colour of the flour samples darkened slightly with irradiation. It was concluded that the most effective doses for the maintenance of the microbiological quality and physicochemical characteristics of the flour were 2 and 3 kGy.

Keywords:
By-products; Peel; Proximate composition; Food irradiation