Comparison of External Quality and Hardness of White Asparagus Spears Produced by Two Different Blanching Methods

Abstract

To clarify the differences between white asparagus (Asparagus officinalis L.) spears produced by two different blanching methods, the soil-mound method and film-cover method, the external appearance and hardness of spears were examined in forcing culture with two-year-old rootstocks. The blanching method had an obvious influence on the color and tightness of the spear tip. Color in the portion 2 cm below the spear tip was more yellowish in the film-cover method than in the soil-mound method. The spear tips tended to be tighter in the soil-mound method than in the film-cover method. These results suggest that both the spear tip color and tightness might be striking visible features to help us discriminate between the two blanching methods. Spears produced by the soil-mound method were greater in diameter in the upper (4 cm from tip) and middle (10.5 cm from tip) portions, and heavier by weight than those by the film-cover method. Spears boiled for 10 minutes from the soil-mound method were significantly tougher in the upper (4 cm from tip) and middle (10.5 cm from tip) sections than those from the film-cover. Therefore, the blanching method was thought to affect spear hardness, which is closely associated with eating and cooking quality.