Effects of Wheat Starch Edible Films on Rancidity and Moisture Uptake of Pistachio Kernels as a New Package

Pistachio kernels were packed in wheat starch/glycerol (Gly) and polyethylenglycole (PEG) films. Wheat starch films were prepared by dispersing 4gr starch in distilled water, and plasticized with Gly and PEG in different levels (Gly =2 and 3 ml/100ml and PEG = 0.0, 0.2, 0.3 and 0.4 ml/100ml). The emulsion films were evaluated for mechanical properties, water vapor transmission rate (WVTR) .Peroxide value and moisture uptake of control (unpacked) and packed pistachio kernels were evaluated for 56 days during storage in ambient temperature (25°C) for 8 weeks. Increasing Gly content of films led to slight increase in Elongation (EL). Increasing the PEG ratio further resulted in an increase in EL for all films. No significant difference in WVT was observed between films made from mixtures of various proportions of Gly with increasing PEG (addition) at all levels of plasticizer. Maximum moisture uptake was found (6.83± 0.08percent) in unpacked (control) pistachio kernels but packaging pistachios in wheat starch films led to minimize moisture uptake. Wheat starch bags reduced the rate of oxidation in pistachio kernels. Incorporation of Gly and PEG in wheat starch films had no significant effect on the PV of packed pistachios. These results suggest that a wheat starch based films is a viable alternative packaging process for pistachio kernels and improvement of shelf life.

کلیدواژه ها:

Wheat starch films ، Pistachio kernels ، Mechanical tests ، WVTR ، Peroxide value ، Moisture uptake