Bio-physical, physiological, and nutritional aspects of ready-to-use cima di rapa (Brassica rapa L. subsp. sylvestris L. Janch. var. esculenta Hort.) as affected by conventional and organic growing systems and storage time

Abstract

The objective of this research was to evaluate the effect of the conventional and organic farming on the bio-physical, physiological and some nutritional aspects of ready-to-use ‘Riccia di San Marzano’ and ‘Cima grande’ cima di rapa genotypes, at harvest (T0) and after 7 (T7) and 14 (T14) days of cold storage. At harvest, the organic product had better overall appearance, higher chlorophyll and β-carotene concentrations and lower glucosinolate levels compared with the conventionally grown product. During the storage period the weight loss was lower in the organic product likely due to reduced respiration activity, particularly in ‘Riccia di San Marzano’. The lower respiratory rate of the organic sprouts could had been involved in a better color retention during the shorter storage time, however after 14days they showed a sharper loss of visual quality and, in particular, the development of off-odors. These differences were probably due to a higher N:S ratio in plant nutrition under the organic cultivation system.Vitamin C, ascorbic acid, dehydroascorbic acid and flavonol concentrations as well as tissue electrolyte leakage were all affected by the storage time and not by cultivation systems. Vitamin C concentration dramatically slowed down during the T0-T7 period, while flavonols progressively increased by 1.5 times during storage, thus leading to an enhancement of total antioxidant capacity of the product. ‘Riccia di San Marzano’ compared to ‘Cima grande’ was richer in antioxidant compounds and, under organic cultivation system, also in nitrates. Stored ‘Riccia di San Marzano’ showed a decrease in nitrate concentration and an increase in antioxidant activity.With the organic farming, cima di rapa visual quality resulted improved both at harvest and after 7days of storage, while after 14days a high development of off-odors occurred. The choice of cultivation system seems not to have modified the antioxidant proprieties of raw or processed product.