Effects of ultrasound irradiation on the properties of apricot kernels during accelerated debitterizing.

In this paper, studies were conducted to investigate the effects of ultrasonically accelerated debitterizing on the physicochemical properties of apricot kernels, such as color, texture, oil content, protein characteristics and amino acids, with UV-Vis spectroscopy, synchronous fluorescence spectroscopy, circular dichroism, electrophoresis, environmental scanning electron microscopy, and thermal property analysis. The results indicate that the novel debitterizing technique has insignificant influences on the oil and protein contents of apricot kernels; meanwhile, the color, texture and activity of beta-glucosidase were substantially improved, greatly contributing to the quality modification and shortening the debitterizing time. In addition, ultrasound greatly influenced the amino acid contents and compositions, the fluorescence spectra and the thermal properties of the apricot kernel proteins. In a word, all these results greatly contribute to our understanding of the debitterizing mechanism mediated by ultrasound irradiation and further prove the feasibility of this novel debitterizing technique in the practical processing of apricot kernels.

Changes of amygdalin and volatile components of apricot kernels during the ultrasonically-accelerated debitterizing.

Ultrasound has been regarded as an efficient novel technique for debitterizing of the apricot kernels, but its influence is severely concerned on the possible epimerization of d-amygdalin to the l-amygdalin, a more potentially toxigenic compound. Considering this, the experiments were conducted to investigate the epimerization of d-amygdalin and the volatile components in the debitterizing water, which were separated and identified by the high performance liquid chromatography (HPLC) and gas chromatography with a mass spectrometer (GC-MS), respectively. The results indicate that the ultrasonically-debitterizing did not cause the epimerization of d-amygdalin to the l-amygdalin, while the procedure can be greatly accelerated due to the rapid mass transfer and degradation of d-amygdalin induced by ultrasound irradiation. In addition, the water from the ultrasonically-debitterizing of apricot kernels exerted more aromas compared with that of the conventional debitterizing, which might have more applications about this kind of water. In a word, ultrasound can be safely applied in the debitterizing industry of apricot kernels.