Abstract:
Dehydrated ripe Jackfruit (waraka) and carrot have a high demand in the local and export
market due to their health benefits and the use as ingredients for the food industry. The
study was carried out to evaluate the effect of different gamma irradiation doses on
physicochemical parameters and microbial quality of dehydrated waraka and carrot in Sri
Lanka. Dehydrated waraka and carrot samples were collected and irradiated at doses of 0
kGy, 2 kGy, 4 kGy, 6 kGy, 8 kGy, and 10 kGy by industrial Co-60 gamma irradiator at
dose rate 5.3 of Gy min-1
. Under physical parameters, water activity and moisture content
were measured for each of the treatments. Total plate count, yeast, and mold count and
coliform counts were determined by using ISO modified method. Antioxidant content by
following DPPH free radical scavenging method, total phenolic content by following
Folin- Ciocalteu (FC) method, and beta carotene content by using AOAC 1980 method
was analyzed in all the irradiated samples and non-irradiated samples and all
physicochemical and microbial treatments were replicated in three times. The average
moisture content of irradiated waraka and carrot samples was 97.04±0.09% and
96.37±0.09% respectively. The average water activity of irradiated waraka and carrot
samples was 0.49±0.00 and 0.50±0.00 respectively. Antioxidant activity and total
phenolic content of the waraka and carrot samples showed no significant difference
(P˃0.05) among different-irradiation doses. However, the content of beta carotene has
been reduced (P˂0.05) with the increase of irradiation-dose. Both irradiated waraka
samples and carrot samples showed a reduction (P˂0.05) of total plate count with the
increase of irradiation dose. There was no growth of yeast and mold and Escherichia
coli in all the gamma-irradiated samples. It was concluded that the most preferable
irradiation doses for preserving the physical and nutritional quality and microbial safety
of dehydrated waraka and dehydrated carrot were 2 kGy and 4 kGy.
Keywords: Dehydration, Waraka, Carrot, Gamma irradiation, Dose
