PHYSIOLOGICAL-CHANGES IN ASPARAGUS SPEARS IMMEDIATELY AFTER HARVEST

Respiratory activity of asparagus spears measured in the field showed a 4-fold increase between the butt and the tip of 190-mm spears. After harvest, there was an immediate rise in the respiration rate, followed by a rapid drop during 24 h at 16°C to a constant level, ∼ 30% of the peak respiration rate. Strong gradients of sugars and proteins were measured along the spears with low levels of sugars and high levels of proteins present in the spear tips. Sugars declined markedly in the first 24 h after harvest, particularly in spear tips. Proteins in spear tips were unchanged 24 h after harvest, but had decreased 25% by 72 h. Total free amino acids remained steady for the first 24 h after harvest, but increased by 75% at 48 h. Asparagine/aspartic acid increased, whereas glutamine/glutamic acid and proline decreased in concentration substantially during the first 24 h after harvest. Tips of taller spears had a lower sugar content and more protein than tips of short spears. © 1990.