Stability of pigments in pistachio kernels

Often the use of suitable packaging is very important to decrease the degradation of food products. The aim of this study was to test stability of pigments (chl a, chl b and lutein) in pistachio kernels stored for 14 months, in the dark, at three different temperatures: 10, 25 and 37°C. The samples were packaged using two films (nylon and EVOH), with and without oxygen scavengers; packages were hermetically closed. Moreover, per each temperature, some samples were packaged in bags without a hermetic seal, as reference. After 14 months, at the end of the storage period, pigments underwent a degradation that was influenced by storage time and temperatures. Lower concentrations were observed at 37°C with a degradation of about: 62% for chl a, 44% for chl b, 57% for lutein. At 10 and 25°C, the samples didn’t show any differences statistically significant and the degradation of pigments were: 46% for chl a, 33% for chl b, 37% for lutein. Among samples, during storage no difference was observed, due to the packaging films or the presence of oxygen scavengers. At 25°C, after 11 months, samples packaged in bags not closed hermetically, showed a presence of moulds and bugs (Plodia interpunctella - Hubner). For kinetic study, rate of degradation of the three pigments fitted a pseudo-zero-order kinetic and it was observed an activation energy of: 11.7 KJ/mol, 12.1 KJ/mol and 18.2 KJ/mol, respectively for chl a, chl b and lutein.