Effect of MAP and Different Atmospheric Conditions on the Sensory Attributes and Shelf life Characteristics of Fresh Pistachio Nuts

Modified atmosphere packaging (MAP) was used to increase the shelf life of fresh in hull pistachio nuts (Pistacia vera L.), meeting the market demand for fresh high quality products. Fresh in hull pistachio nuts were stored at 5°C and three different gaseous conditions including 10% O2, 20% CO2 and 70% N2 (MAP1), 100% CO2 (MAP2) and ambient atmosphere for 42 days. The samples of 300 g of pistachio nuts were packaged in sealed high barrier poly propylene (PP) bags (26×20 cm). The permeability of films for CO2 was 3910 cm3/m2 dbar at 23°C and 50% RH. The thickness and the surface of the used films were 2.00 mm and 78.90 cm2, respectively. External appearance, weight loss, firmness and color attributes and microbial growth were investigated at regular intervals throughout the storage period. Significant differences were found between packaged and unpackaged fresh in hull pistachio nuts in the most of parameters considered. The firmness in the nuts decreased markedly in control samples. This trend was also observed in the nuts stored under 10% O2, 20% CO2 and 70% N2. However, the firmness in those nuts stored in 100% CO2 increased. On the other hand weight loss was quite slighter in the samples stored at MAP comparing to the control ones (p<0.01). MAP had a significant effect (p<0.01) on the storage time, with the external appearance being the limiting factor for shelf-life of pistachio nuts. Storage in 100% CO2 and 5°C showed the best results among the treatments in terms of retaining physical properties and sensory attributes, increasing the health and extending the shelf-life of fresh in hull pistachio nuts.