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Investigation of Packaging Systems for Shelled Walnuts Based on Oxygen Absorbers

Jensen, Pernille N., Sørensen, Gitte, Brockhoff, Per, Bertelsen, Grete
Journal of agricultural and food chemistry 2003 v.51 no.17 pp. 4941-4947
air, cold storage, nitrogen, oxygen, packaging, packaging materials, permeability, regression analysis, storage temperature, taste, walnuts
Storage of nuts at a high oxygen concentration results in rancid nuts whereas storage at a low oxygen concentration results in fine-tasting nuts. During a 13 month experiment, packaging of walnuts with an oxygen absorber was compared to packaging in nitrogen or atmospheric air. At the same time, the effects of oxygen permeability of the packaging material and storage temperature (11 and 21 °C) were investigated by determination of hexanal and rancid taste of the walnuts. The optimal storage condition for walnuts is at 11 °C or lower, eventually combined with an oxygen absorber. However, without chilled storage and use of an oxygen absorber, it is possible to obtain an acceptable quality of walnuts with a packaging material having a very low oxygen permeability (e.g., laminate with EVOH) combined with nitrogen flushing. The results also revealed that the development of hexanal during time can be described by a second-order polynomial regression model.