Fruit pits recovered from fourteen genotypes of apricot (Prunus armeniaca L.) as potential biodiesel feedstock

Abstract

Kernels recovered from fruit pits of fourteen apricot (Prunus armeniaca L.) genotypes were tested for future application as feedstock for biodiesel production. The difference between the lowest and the highest oil yield between studied samples was over two-fold and reached between 27.1 and 58.7% (w/w) dw. The oleic and linoleic acids were the two dominant fatty acids in apricot kernel oils; however, their content was affected meaningfully by the variety and amounted to 38.5–67.2% and 26.4-54.8%, respectively. Two significant correlations (p < 0.000005) were found between oil yield in kernels of different apricot genotypes and two fatty acids, oleic and linoleic (r = 0.947 and r = -0.927, respectively). The biodiesel parameters of fourteen apricot genotypes were calculated empirically according to previously developed equations based on the fatty acid methyl esters composition of the potential feedstock. The European biodiesel standards of kinematic viscosity, cetane number, density and iodine value were met for thirteen investigated samples. The exception was noted for genotype HL PSŠ 5. The recorded differences between minimum and maximum value of individual biodiesel parameters calculated empirically for various apricot genotypes differed as follows: 0.20 mm²/s (kinematic viscosity), 4.9 (cetane number), 0.06 MJ/kg (higher heating value), 0.0028 g/cm³ (density), 15.6 I₂/100 g (iodine value), 1.67 °C (CFPP) and 2.15 h (induction period). The logarithmic regression model in comparison to linear regression model, better expressed the relationship between physicochemical properties of biofuel and the ΣPUFA/(ΣSFA+ΣMUFA) ratio. To confirm the usefulness of the applied empirical equations for biodiesel parameters prediction of the apricot feedstock, five cold-pressed apricot kernel oils of different origin and with a varied composition of fatty acids were tested experimentally and compared with the values calculated empirically.

Practical applications: Apricot kernels have limited use in food industry due to a high content of the amygdalin. Therefore, application of apricot kernels as potential feedstock for the biodiesel production seems to be reasonable, especially due rich oil yield (up to even 60%). This paper describes the impact of the apricot genotype on the potential application in the biodiesel industry as well as the relationship between the oil yield and apricot biodiesel quality. Obtained biodiesel parameters of fourteen apricot (Prunus armeniaca L.) genotype oils can help estimate the economic perspectives of utilization as a potential energy source. The present study may contribute to the more targeted use of the apricot (Prunus armeniaca L.) kernels and promotes the efficient management of the plant material and environmental sustainability.

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