Effect of Location and Age of Plantation On Organoleptic Characteristics of a Typical Italian Asparagus Crop

Asparagus is a very common and important vegetable in the Veneto region especially in the areas of Treviso, Vicenza and Padova provinces, where it is also a typical and historical product. Recently the demand for high of quality produce (nutritional value) has been increasing dramatically. For green asparagus, and in particular for typical cultivar grown in Northern Italy, the information on these issues are limited. For these reasons experiments have been carried out in order to evaluate nitrates, nitrites, polyphenols and pigments contents and antioxidants activity of marketable product of green asparagus cv Eros, grown in two areas of Veneto region. The qualitative analysis in green shoots, were performed in 2008 at the Department of Environmental Agronomy and Crop Science of the University of Padova on samples coming from the 2 areas (Pd and Ba). The first asparagus plantation considered was three years old and the second one eight years old. During harvest (from April till May), six sampling were collected. After each harvest, shoots were calibrated, washed and placed at 4 C° till next day. For qualitative analysis only extra class shoots (diameter >16 mm) were used. Shoots were weighted and then cut to 270 mm from the apex in order to separate not marketable portion from the commercial one. The latter fraction was cut in 3 parts 90 mm long (apical (A), intermediate (I) and basal (B)) to evaluate quality characteristics of each part. Results showed that asparagus from Pd had a lower content of dry matter but a greater weight. The nitrate content, which was always far below the recommended WHO limits, was not influenced by location, while considering the part of shoot, as expected, a decreasing trend from the base to the apex was observed. For nitrites there were no significant differences between locations and among shoot parts. The pigments content increased during the advancing of the harvest season in Pd that showed the highest values. The content of these compounds strongly increased moving from the base to the top of the shoot and the chlorophyll a content was higher than the chlorophyll b and the pool xanthophylls + carotenoids. The antioxidants activity and polyphenols analysis showed that the upper part is the richest in these compounds mainly because directly exposed to stress situations (light) caused by the shoot emergence through the soil and by the increasing of xanthophylls and carotenoids content.