Tunisian Researchers investigated the biological properties and natural preservative effect of the essential oil from pistachio by-product and the results were published in the Journal of Food Measurement and Characterization.

Essential oil was extracted for the first time from pistachio by-product (EOPB) by hydrodistillation then analysed by gas chromatography-mass spectrometry (GC-MS). Forty two different components were identified in EOPB. The major components were E-9-Octadecen-1-ol acetate, 11-Hexacosyne, 1-Eicosanol, 3-Eicosanol and 2-Methyl-EE-3,13-Octadecane. The antioxidant and antibacterial activities of EOPB were also investigated. Therefore, EOPB displayed high antioxidant activity, in terms of DPPH-radical scavenging effect (IC₅₀=4.6 mg/ml), beta-carotene bleaching inhibitory effect (IC₅₀=2.7 mg/ml) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging effect (IC₅₀=0.2 mg/ml). The antibacterial activity of EOPB was also tested against eight strains. The results indicated that EOPB has the highest activity against Salmonella thyphi, Enterococcus faecalis and Escherichia coli at the concentration of 100 mg/ml. Finally, the EOPB applications as food preservatives were studied. Indeed, the effect of different percentages (0.1 and 0.5%, w/w) of EOPB on thiobarbituric acid reactive substances (TBARS), meat color, and microbiological parameters of ground beef meat stored at 4°C for 9 days was evaluated.

The findings showed a reduction in lipid oxidation, meat color stability and an inhibition of bacterial growth in minced beef meat containing EOPB. In summary, the results suggested that EOPB can be used as natural preservatives for future application in meats industries.