PREHARVEST AND POSTHARVEST STRATEGIES FOR REDUCING NITRATE CONTENT IN ROCKET (ERUCA SATIVA)

The occurrence of nitrate and nitrite in Mediterranean fresh salad vegetables and its modulation by preharvest practices and postharvest conditions

Winter and summer nitrate/nitrite concentrations in 11 salad vegetables were surveyed using a validated HPLC-DAD method. Nitrate was highest in rocket, both in winter (x̅ = 3974 mg kg^-1 fw) and summer (x̅ = 3819 mg kg^-1 fw). High nitrate accumulators included spinach, purslane, chards, dill, coriander and parsley. Wide intra-species variability and levels in excess of permitted maxima highlighted the importance of monitoring vegetable production methods to protect consumer health. Occurrence of detectible nitrite (14-352 mg kg^-1 fw) was most frequent in winter head cabbage. Three additional experiments examined the seasonal effects of nitrogen (N) fertilization rate, application method, formulation and postharvest storage on nitrate and nitrite levels in lettuce, rocket and spinach. Violation of current nitrate limits is likely when total N exceeds 200 kg ha^-1, particularly in rocket and spinach. Postharvest nitrate reduction requires exogenous microbial nitrate reductase activity, which is unlikely to be achieved without visible loss of quality.

Evaluation of Two Wild Populations of Hedge Mustard (Sisymbrium officinale (L.) Scop.) as a Potential Leafy Vegetable

The minimally processed industry is always looking for produce innovation that can satisfy consumer needs. Wild leafy vegetables can be a good source of bioactive compounds and can be attractive for the consumer in term of visual appearance and taste. In this work, Sisymbrium officinale (L.) Scop., commonly called hedge mustard, was grown in a greenhouse and evaluated as a potential leafy vegetable. Two wild populations, Milano (MI) and Bergamo (BG), were grown in peat substrate and harvested at the commercial stage for the minimally processing industry. Leaf pigments such as chlorophyll and carotenoids were determined as well as chlorophyll a fluorescence parameters. Total sugars, antioxidant compounds such as ascorbic acid, phenolic index, total phenols, anthocyanins, and nitrate were determined at harvest. Significant differences between wild populations were found in April with higher nitrate content in BG, 2865 mg/kg FW than in MI, 1770 mg/kg FW. The nitrate levels of S. officinale measured in the present study are significantly lower than the maximum NO₃ level allowed in other fresh leafy vegetables. Ascorbic acid measured in November was higher in MI compared BG with values of 54.4 versus 34.6 mg/100 g FW, respectively. The chlorophyll a fluorescence data showed that BG reached optimal leaf functionality faster than MI. Overall results indicated that Sisymbrium officinale (L.) Scop. can be suggested as a potential leafy vegetable for the minimally processed industry.

Quality of fresh-cut products as affected by harvest and postharvest operations

There is a rising demand for fresh-cut convenience products with high quality and nutritional standards that needs to be met by the fresh-cut industry. It is well known that harvest and postharvest handling of fresh produce has a paramount impact on its quality and storage, although most of the existing literature has focused on these impacts related only to fresh produce that is destined for the final consumers. Indeed, current harvest methods and postharvest technologies have improved fruit and vegetable handling and distribution processes by slowing down physiological processes and senescence. Nonetheless, these technologies and methods may influence the quality of fresh produce as raw material for fresh-cut processing as a result of the dynamic responses of fresh produce to handling procedures and treatments. Here, we review the existing literature on the challenges facing the fresh-cut industry, focusing on the impact of harvest, maturity, and handling of fruit and vegetables on the quality of raw materials, as well as the implications for fresh-cut products. The review also highlights areas for further research with the aim of enhancing the sensorial, nutritional and biochemical quality of such products. © 2018 Society of Chemical Industry.

Nitrates and glucosinolates as strong determinants of the nutritional quality in rocket leafy salads

Rocket is an important leafy vegetable crop and a good source of antioxidants and anticancer molecules such as glucosinolates and other sulfur compounds. Rocket is also a hyper-accumulator of nitrates which have been considered for long time the main factors that cause gastro-intestinal cancer. In this review, the content of these compounds in rocket tissues and their levels at harvest and during storage are discussed. Moreover, the effect of these compounds in preventing or inducing human diseases is also highlighted. This review provides an update to all the most recent studies carried out on rocket encouraging the consumption of this leafy vegetable to reduce the risk of contracting cancer and other cardiovascular diseases.