[P004] Poster

1:00 PM - 1:50 PM JST(4:00 AM - 4:50 AM UTC)

[P02-158] Effect of Distillation Apparatus Material on the Quality of Sweet Potato Shochu

○Shugo Kurazono¹, Yumiko Yoshizaki¹, Taiki Futagami¹, Hisanori Tamaki¹, Kazunori Takamine¹ (1. Kagoshima Univ. (Japan))

Keywords:

Sweet potato shochu,Distillation,Copper,Stainless- steel

Shochu is a Japanese traditional distilled spirit. Sweet potato shochu is one of popular shochu in Japan. Stainless steel-still is mainly used in shochu distillation. However, some distilleries also use copper, wood, or tin-stills. Although it is empirically known in production settings that the material of the distillation apparatus affects shochu quality, the scientific basis for this effect has not yet been fully clarified. In this study, we investigated the effects of these materials on the quality of sweet potato shochu during distillation using a glass distillation apparatus fitted with either copper or stainless-steel plates.The aroma component analysis showed that the stainless steel-distilled shochu (SUS), compared with the glass-distilled shochu without inserted metal plates (GL), exhibited increased levels of lipid-derived compounds such as hexanal and ethyl 9-oxononanoate. In contrast, phenolic and terpene compounds, including 2,4-di-tert-butylphenol, 2,3-butanediol, 4-vinylguaiacol, p-mentha-1,5,8-triene, cosmene, and δ-cadinene, were decreased. Among these compounds, 4-vinylguaiacol, p-mentha-1,5,8-triene, cosmene, and δ-cadinene increased in the copper-distilled shochu (Cu), indicating that the material of the distillation apparatus affects the formation behavior of aroma compounds. In addition, the sulfur compound dimethyl trisulfide (DMTS) was significantly lower in Cu compared with SUS, consistent with previous studies on whiskey. Sensory evaluation showed that Cu had significantly stronger sweet aroma than SUS and tended to have higher fruity aroma and a richer, thicker mouthfeel. On the other hand, although not significant, sulfur-like aroma received a higher score in SUS. DMTS (threshold: 0.25 μg/L) was 5.6 μg/L in GL, 0.3 μg/L in Cu, and 8.9 μg/L in SUS, confirming a significant reduction in Cu. Hexanal (threshold: 24 μg/L) was 129 μg/L in GL, 131 μg/L in Cu, and 817 μg/L in SUS, showing a significant increase in SUS; however, no difference in grassy aroma intensity was observed in the sensory evaluation.Furthermore, to evaluate the effect of copper plate position on DMTS concentration, we examined the following four conditions: copper inserted into all parts of the apparatus, namely the pot, lyne arm, and condenser; into the lyne arm and condenser; into the pot and condenser; and into the pot and lyne arm. DMTS remained low under the first three conditions. In contrast, when copper was inserted only into the pot and lyne arm, without copper in the condenser, DMTS was high. These results suggest that the presence of copper in the condenser is important for reducing DMTS.Overall, these findings indicate that the material of the distillation apparatus greatly influences the flavor characteristics of sweet potato shochu, and that the presence of copper in the condenser may be particularly important for DMTS reduction.