Stability of pigments and oil in pistachio kernels during storage

P>This work tested the stability of pigments (chlorophyll [chl] a and chlorophyll [chl] b, and lutein] and oil in pistachio kernels stored up to 14 months at three different temperatures: 10, 25 and 37 degrees C. The samples were hermetically packaged using two films (nylon and ethylene vinyl alcohol) with and without oxygen scavengers. For each temperature, reference samples were packaged in open bags. For both the oil and pigments, no differences were observed during storage, irrespective of packaging or oxygen scavengers. After 14 months, the oil showed very few changes: a slight increase in acidity and peroxide value (PV) irrespective of storage temperature; the spectrophotometric indices K-232 and K-268 remained the same. As for pigment stability, the lowest concentrations were observed at 37 degrees C with a degradation of about 62% for chl a, 44% for chl b and 57.5% for lutein. At 10 and 25 degrees C, the samples showed slight differences, the pigments degradations were about 46% for chl a, 33% for chl b and 37% for lutein. The degradation rate constants for the three pigments fitted a pseudo-zero-order kinetic in which Ea was 11.7 kJ mol-1, 12.1 kJ mol-1 and 18.2 kJ mol-1 for chl a, chl b and lutein respectively.