The effects of irradiation on lipid oxidation of almonds
G. L. SANTOS-NORRIS, Graduate Student, Chapman University, 5312 Cobb Drive, Dayton, OH 45431, D. R. Connell, Senior Chemist, R&D, Con Agra, 1645 West Valencia Drive, Fullerton, CA 92833-3860, and A. Prakash, Professor, Food Science and Nutrition, Chapman University, 333 North Glassell Street, Orange, CA 92666.
Insect infestation of tree nuts can cause tremendous losses of these globally marketed commodities. Chemical fumigation with pesticides, such as methyl bromide, is gradually being phased out due to negative side effects associated with residues. Irradiation has been proposed as an alternative means of pest control; however, perceptions exist that irradiation would lead to oxidative rancidity in these high fat foods.
The objective was to evaluate the effects of irradiation on lipid oxidation of shelled almonds during accelerated storage.
Almonds were exposed to gamma irradiation from a Cobalt60 source to receive dosages of 0.5, 1.0, and 2.0 kGy and stored at 35°C for 77 days. Every week, oil from the almonds was obtained by cold pressing. Lipid oxidation was measured using dynamic headspace-capillary gas chromatography (DHS-GC) to determine changes in volatile compounds. Percent free fatty acid (%FFA) and peroxide values (PV) were also measured to assess the extent of lipid oxidation.
There were no differences in PV and %FFA values, as well as volatile headspace compounds, due to irradiation as indicated by analysis of variance (a=0.05); although, there was a small effect of storage time on certain volatile headspace compounds.
These results show that low dose irradiation does not promote lipid oxidation in almonds. Previous studies have shown that irradiation of almonds at 0.5 kGy is an effective means of post harvest pest control. Other studies have shown no sensory changes in almonds up to 2 kGy. Thus, irradiation has the potential to be an effective means for insect disinfestation in almonds.
Session 30A, Food Chemistry: Lipids