Application of electron beam irradiation for improving the microbial quality of processed laver products and luminescence detection of irradiated lavers
2018
Lee, E.J., Kyungpook National University, Daegu, Republic of Korea | Kim, G.R., Kyungpook National University, Daegu, Republic of Korea | Kashif Ameer, Kyungpook National University, Daegu, Republic of Korea | Kyung, H.K., Kyungpook National University, Daegu, Republic of Korea | Kwon, J.H., Kyungpook National University, Daegu, Republic of Korea
The laver (Porphyra spp.) is normally processed in three kinds of products: dried laver (DL), roasted laver (RL), and seasoned roasted laver (SL). This work evaluated the effects of electron beam (E-beam) irradiation at different doses (0, 1, 4, 7, and 10 kGy) on microbiological and physicochemical qualities and detection characteristics of irradiated samples by luminescence analysis. E-beam irradiation resulted in dose-dependent microbial reductions, showing that 1 kGy destroyed initial coliforms (less than 2.35 log CFU/g) to undetectable levels (less than 10 CFU/g), while 7 kGy (approved dose for seaweed in Korea Food Code) reduced total aerobic bacteria (3.72-6.33 log CFU/ g) and yeasts and molds (2.05-4.98 log CFU/g) by about 2 log cycles. Chlorophyll content remained unaffected in irradiated samples as compared to control; however, carotenoids content and Hunter's b values (degree of yellowness) showed a tendency to decrease in a dosedependent manner (p less than 0.05). However, E-beam irradiation less than 7 kGy did not significantly affect sensory properties of the processed laver products. Irradiated laver products (DL, RL, and SL) could be screened and detected by analyzing photostimulated luminescence and thermoluminescence, respectively, from the non-irradiated ones. The overall results indicated that E-beam irradiation is effective for ensuring the improved microbial quality (less than 4 log CFU/g) for the exporting processed laver products without apparent quality changes.
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