Stability of pigments and oil in pistachio kernels during storage

This work tested the stability of pigments (chlorophyll [chl] a and chlorophyll [chl] b, and lutein] and oil inpistachio kernels stored up to 14 months at three different temperatures: 10, 25 and 37 C. The samples werehermetically packaged using two films (nylon and ethylene vinyl alcohol) with and without oxygenscavengers. For each temperature, reference samples were packaged in open bags. For both the oil andpigments, no differences were observed during storage, irrespective of packaging or oxygen scavengers. After14 months, the oil showed very few changes: a slight increase in acidity and peroxide value (PV) irrespectiveof storage temperature; the spectrophotometric indices K232 and K268 remained the same. As for pigmentstability, the lowest concentrations were observed at 37 C with a degradation of about 62% for chl a, 44%for chl b and 57.5% for lutein. At 10 and 25 C, the samples showed slight differences, the pigmentsdegradations were about 46% for chl a, 33% for chl b and 37% for lutein. The degradation rate constants forthe three pigments fitted a pseudo-zero-order kinetic in which Ea was 11.7 kJ mol)1, 12.1 kJ mol)1 and18.2 kJ mol)1 for chl a, chl b and lutein respectively.