Browsing by Author "Ranasinghe, R.D.R."

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Effect of Gamma Irradiation on Microbiological and Physicochemical Properties of Dehydrated Carrot (Daucus carota L.) and Dehydrated Ripe Jackfruit (Waraka) (Artocarpus heterophyllus L.)
    (Uva Wellassa University of Sri Lanka, 2020) Madushani, R.V.C.; Wijesinghe, W.A.J.P.; Ranasinghe, R.D.R.; Silva, P.D.P.M.D.
    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
  • Thumbnail Image
    Item
    Impact of Gamma Irradiation on Control of Microorganisms in Export Oriented Moringa (Moringa oleifera) Powder and Flakes
    (Uva Wellassa University of Sri Lanka, 2019) Karunanayake, K.M.S.P.L.; Rathnayake, R.M.N.P.; Ranasinghe, R.D.R.; Wijesinghe, W.A.J.P.
    Moringa (Moringa oliefera) has a growing demand in export market mainly due to its health benefits. The study was carried out to evaluate the effect of different gamma irradiation doses to physical parameters and microbial quality of export oriented Moringa powder and flakes in Sri Lanka. Homogenized Moringa samples were collected from a particular exporter. Samples were 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 Gy min-1. Under physical parameters, water activity, moisture content, color and infusion color (∆E value based on L*, a*, b* in Hunter color scale) were measured for each of the treatment. Under microbial safety, total plate count, yeast and mold count and coliform counts were done. All treatments were replicated in three times. Average moisture content of irradiated Moringa powder and flakes were 6.32±0.04% and 6.09±0.03% respectively. Average water activity of irradiated Moringa powder was 0.41±0.00 and irradiated Moringa flakes was 0.44±0.03. Mean values of color and infusion color of irradiated Moringa powder and flakes were not significantly different (P<0.05) with the control sample. The average total plate count in control sample of powder was 1.29×107±2.47×105 CFU g-1 and flake was 4.5×105±3.71×105 CFU g-1, both irradiated Moringa samples showed significant reduction in dose dependent manner. No Yeast and Mold counts were observed in all the treated samples. Escherichia coli were identified in 0 kGy and 2 kGy samples only. It is concluded that the 6 KGy was better for Moringa flake and 8 kGy was better for Moringa powder for microbial safety, while preserving the physical quality.