Effects of Ionizing Radiations on Plant Tissues. V. Some Effects of Gamma Radiation on Lettuce Leaves^a

Abstract

SUMMARY The effect of gamma radiation from a Cobalt60 source upon lettuce tissue was studied. The radiation‐induced softening of leaf discs was assessed with an instrument designed to measure the bending of the disc under application of a given weight. It is estimated that the “threshold dose” of radiation‐induced softening of lettuce is between 600 and 1,000 Kilorad. Lettuce leaf tissue thus appears more resistant to the softening effect of gamma radiation than the storage‐type tissues of apples, carrots, or beets. The radiation‐induced changes in the respiratory activity of lettuce were also studied, both during and after irradiation. Although both oxygen consumption and carbon dioxide evolution are stimulated during irradiation, the response subsides to near‐normal rates shortly after irradiation is stopped. There is some indication that the magnitude of the respiratory rate stimulation response is based primarily upon dose rate. A comparison of softening and respiratory rate measurements indicates that the tissue softening is probably not directly related to the respiratory stimulation that occurs during gamma irradiation.

Effect of Gamma Radiation Upon Cherries

“…Changes in the soluble-insoluble pectin ratio appear to be an excellent index of response. These are similar to changes reported for some other tissues (Kertesz et al, 1964;Massey et al, 1964). Fig.…”

Quality of Gamma Ray-irradiated Iceberg Lettuce and Treatments to Minimize Irradiation-induced Disorders

“…There have been a number of studies regarding the effect of MAP on irradiated cut lettuce. For example, Massey et al (2006) found that irradiation increased O 2 consumption and CO 2 production of lettuce. Fan andSokorai (2002, 2011) found that fresh-cut Iceberg lettuce packed in MAP and irradiated at 1 kGy had less tissue browning and better overall visual appearance compared with the non-irradiated one.…”

An Instrument for Measuring Rheological Properties by Bending. Application to Food Materials of Plant Origin*

“…The 'Droopmeter' developed by Gallop (1971) for measuring the 'droop' or sag of potato french fries operates on a cantilever principle. In a somewhat different approach, Massey et al (1961) subjected circular discs of lettuce to bending by placing them between the ends of two vertically mounted steel rods and lowering a 'weight' ring around the upper rod in order to make contact and bend the protruding disc. The amount of deflection produced by the weight was used as a measure of crispness, after normalizing for variations in thickness.…”