Awamori Quality Measurement by Using Near Infrared Spectroscopy and Fourier Transform Infrared Spectroscopy

Abstract

　Near-infrared s pectroscopy and Fourier transform infrared spectroscopy (FTIR) were used to develop simple, nondestructive quality estimation models for Okinawa Awamori based on its physical properties and chemical components. Further, classifying Awamoriby the producing areas by using FTIR was examined. No differences were observed between the analyzed Awamori samples in terms of the viscosity and density; however, minor differences in the quantities of fusel oil, aldehyde, and methyl alcoholwere noted. Particularly, the acidity values of "Seifuku", "Miyanotsuru", and "Awanami" produced in the Yaeyama Districtwere higher than the acidity values in other products.Except for the above Awamori samples, in other samples, a correlation coefficient (R) of －0.82 was observed between a cidity and pH and that between acidity and aldehyde was 0.52. The fusel oil and methyl alcohol quantityshowed high values in the northern and southern parts of the Okinawa Islandand Miyako and Yaeyama Islands. The fusel oil, aldehyde, methyl alcohol quantities, a cidity, and pH were estimated with high accuracy by using FTIR and the R values were 0.91, 0.74, 0.78, 0.98, and 0.80, respectively. Cluster classification was used along with FTIR to successfully distinguish the Awamori samples by the producing areas.