Effects of blanching method on hardness and quality components of white asparagus (Asparagus officinalis L.) spears harvested in rootstock-planting: 'Fusekomi' forcing culture.

摘要

In Japan, two blanching methods for blocking sunlight are used for growing white asparagus spears, namely, the traditional soil-molding method and the shading-film method. The objective of this study was to compare the influence of the shading-film and soil-molding method on the quality of white asparagus spears cultivated in winter. We investigated the effects of the blanching method on the hardness and sugar (fructose, glucose, and sucrose) and saponin (furostanol saponins, e.g. protodioscin) content in white asparagus cultivated by using the "Fusekomi" forcing culture system in winter. The hardness of the top and middle parts of spears was significantly higher in those blanched using the soil-molding method than in those blanched using the shading-film method; however, no significant difference was observed in the hardness of the bottom parts in the spears of the two methods. Throughout the harvest period, the protodioscin content in the bottom sections of the spears was higher in those blanched using the soil-molding method than in those blanched using the shading-film method. No significant difference was observed in the sugar content of the spears blanched using either method.