Submitted to: Journal of Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 1, 1995
Publication Date: N/A
Interpretive Summary: Fresh-cut spinach generally are marketed in a film type package, where the internal oxygen can be depleted by respiration to a dangerously low level; the level at which the undesirable anaerobic respiration is induced. Neither the minimum safe oxygen level nor the quality condition of spinach at near the minimum safe level is known, so this was researched. Results of the research indicated that oxygen below 0.4 percent induced a very large amount of anaerobic respiration and only a slight amount was induced at 0.8 percent oxygen atmosphere. The slight amount of anaerobic respiration at 0.8 percent did not deleteriously affect the weight, color, or chlorophyll contents of spinach. Respiration was reduced 40 percent by the 0.8 percent oxygen atmosphere, thus due to no deleterious effect, oxygen can be allowed to go down to 0.8 percent with a beneficial effect, but levels below 0.4 percent can become undesirable and is not recommended. .This information will be useful to scientists and industry people involved in fresh-cut marketing of spinach.
The effect of low levels of oxygen, above the extinction point, for modified atmosphere storage of spinach was evaluated. The extinction point of spinach leaves at 0 degrees and 5 degrees C was found to be below 0.4 percent but above 0.2 percent O2, thus 0.8 percent O2 was selected as the minimum level that would be considered acceptable for the low O2 atmosphere estudy in which respiration rate (O2 uptake and CO2 production), weight loss, color and chlorophyll content of three spinach cultivars held at 0 degrees and 5 degrees C were determined. The average O2 uptake, over temperatures and cultivars, was reduced by 53 percent and CO2 production was reduced by 35 percent in a 0.8 percent O2 atmosphere relative to air storage. The RQ increased to about 1.5 at 5 degrees C. This implied that the threshold of anaerobic respiration was achieved but was not harmful to the tissue because there were 30 percent and 54 percent fewer deteriorated leaves in 0.8 percent O2 than in an air atmosphere at 0 degrees and 5 degrees C, respectively. Respiration rates were about 2.3 times greater at 5 degrees C than at 0 degrees C and were similar among the cultivars. The low O2 atmosphere had no beneficial effect on weight loss, color or chlorophyll content at either 0 degrees or 5 degrees C. These results indicate that the O2 level can be as low as 0.8 percent in modified modified atmosphere packaging without quality loss due to anoxia.