91C-3 |
Low energy electron irradiation of an apple |
R. G. MOREIRA, G. Brescia, and M. E. Castell-Perez. Biological and Agricultural Engineering Department, Texas A&M University, Scoates Hall, 310, College Station, TX 77843-2117 The viability of pathogenic organisms on the surface of fresh fruits and vegetables can be significantly reduced by low energy electron beam irradiation. The most difficult technical challenge for surface irradiation of fruits and vegetable is the need to achieve a uniform dose distribution over the entire surface.This is particularly difficult if there are deep recesses such as the area of the stem of an apple, or convoluted surfaces such as some type of lettuces. The main goal of this research was to calculate the dose distribution after irradiation with a low energy electron source in a complex shaped apple using Monte Carlo simulation. A software package, MCNP (Monte Carlo N-Particle), was used to simulate an electron beam irradiation from a 1.0, 1.5 and 2.0 MeV source on an apple. The apple radius was 4.4 cm and 3.6 cm and the volume was divided into small segments to calculating energy deposition as a function of angular position and radius. Irradiation of the apple by a beam 1 cm wide and 10 cm high, propagating horizontally to the produce was simulated. A combination irradiation with the axis of the apple tilted 30º against and 30º towards the source irradiation position after one full revolution resulted in the most uniform dose distribution for the three source energies. The average dose at the front of the apple was in the range from 1.2 to1.6 kGy and 3.6 to 4.0 kGy at the top and bottom. The dose distribution was then correlated with the logarithm of the microorganism survival fraction on the surface of the apple by using the simple target theory. At least two logarithmic reductions in microorganism were obtained at all positions on the surface of the apple.
Session 91C, Food Engineering: Food process engineering
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