Spinach is characterized by having a high water content and different vitamins and minerals. However, this vegetable could have high oxalate and nitrate concentrations and can affect human health if consumed.The aim of this study was to evaluate the nitrogen fertilization effect on the yield, nitrate and oxalic acid content of spinach produced in an autumn-winter cycle under different growing systems. Spinach was grown in soil in a greenhouse and in an open field at the experimental field of the Faculty of Agronomy of the University of Buenos Aires. Soil treatments were 0.50 and 100 kg N.ha-1. Another culture was in substrate (perlite) where nitrogen supply restriction was applied 15 days before harvest. Color, leaf area, harvest index, yield, nitrate and oxalic acid levels were determined for each crop at harvest. Leaves were selected and 60 g were packaged in 31 micron polyolefin bags. Bags were stored in a refrigerated chamber at 5 ºC for 9 days. The nitrate and oxalic acid content of spinachwas also determined at the end of the storage period. Yield and leaf area were higher with 100 kg N.ha-1 without differences between greenhouse and open field. Oxalate content was higher in spinach from the open field, showing the highest value in the case of 100 kg N added, without changes at the end of postharvest period. The maximum nitrate content was 2.7 in greenhouse with 100 kg N.ha-1. The nitrogen restriction reduced the commercial yield, oxalic acid and nitrate content at harvest in perlite. The difference was maintained postharvest, except for the nitrate content.

The quality of food is determined by different aspects: type and quantity of nutrients, quality and sanitary safety. However, one of the most important aspects that will ultimately determine its acceptance or rejection is related to the consumers’ subjective perception, that is, aspects related to the preference of color, taste, texture, consistency and presentation of the product. The objective of this work was to evaluate consumers’ acceptability and preference of lettuce grown with and without incorporation of swine deep-litter compost. The experiment was carried out in the FCA-UNR, Zavalla, Santa Fe (33º 01´ S; 60º 53´ W), comparing two samples: M0, without incorporation of compost into the soil and M1 from lettuce grown with application of deep-litter compost (12 kg m-2). Lettuce plants were harvested the same day of the tasting test. Twenty plants from each treatment were randomly harvested, subsequently conditioned and offered to 72 participants at random. A hedonic questionnaire was used, with the following parameters: global appearance, aroma, bitter taste and texture, allowing participants to make free comments on each attribute. At the same time, participants were asked to choose one of the samples based on their preference. Results were analyzed with Kruskal Wallis test (Infostat Professional) and Roessler test. Under the conditions of the sensory evaluation carried out in this work, lettuce from the treatment with swine deep-litter compost added to the soil would have a greater probability of being chosen by the consumer.

Horticulture constitutes an engine of development for countries like Argentina that have the challenge of optimizing the consumption of vegetables in quantity and diversity, given that the plurality of species and varieties consumed is traditionally very limited. In this sense, the objective of this work is to analyze the current importance of the Argentine horticultural sector, taking as reference the information generated by the main Argentine concentrator market: Mercado Central de Buenos Aires (MCBA), where annually between 17- 20% of the national total is commercialized. The variables considered were: diversity and volume (t.ha-1) of vegetables marketed, main vegetables consumed (PHC) (potato, tomato, squash, onion and carrot) and monthly evolution of the marketing of leafy vegetables (EHH), by province and main varieties marketed, in 2018. A total of 69 species was recorded among vegetables (60) and aromatics (9). In vegetables, 80% of the total volume marketed corresponded to 5 species: potato (38%), tomato (14%), onion (12%), squash (6%), carrot (6%), summer squash (3% ), pepper (3%); followed by lettuce, sweet potato, corn, melon, cassava, watermelon, eggplant, chard, cabbage, cucumber, spinach, beets, green onion, garlic, broccoli, parsley, green bean, celery, cauliflower, pea, arugula, leek, sweet corn , fennel, accuse, asparagus, artichoke, endive, radicheta, cabbage, bean, turnip, Brussels sprout, radish, pack-choy, chicory, salsify, mushrooms, potatoes, radicchio, radicchio, bean, endive, grelo, soybean sprout, kale, cress, ciboullete, shallot, achojcha, thistle, turmeric and chervil. Regarding aromatics, the order of importance corresponded to: basil, ginger, coriander, mint, oregano, sage, turnip, rosemary and other aromatics. Although the diversity of commercialized species is encouraging, a greater balance in consumption is a priority.

The search for good quality hardwood vegetables has grown, and consumers are becoming increasingly demanding as to the appearance, color and size of these products. Chemical quality is one of the main programs used in food control. The objective of this paper was to determine the macronutrient contents in leafy vegetables marketed in open fairs in the city of São Luís. The experiment was carried out in the laboratory of mineral nutrition of plants of the engineering nucleus of the State University of Maranhão. From a universe of 14 hardwood vegetables, six of the highest consumption in five free fairs through the application of questionnaires, were selected. Sulfuric digestion/ hydrogen peroxide and P and K determined the N contents by nitroperchloric digestion. The six leafy vegetables selected were: Lactuca sativa, Allium schoenoprasum, Coriandrum sativum, Brassica oleracea var. capitata, Talinum triangulare and Hibiscus sabdariffa. It was verified that the regional vegetables are the most consumed by the population, with emphasis on the non conventional vegetables Hibiscus sabdariffa and Talinum triangulare. The results obtained in the chemical analyses showed potassium and phosphorus deficiency for the samples of Lactuca sativa and Brassica oleraceacapitata in the five fairs studied, indicating inadequate mineral fertilization (excess or deficiency) of these vegetables. While for other unconventional vegetables, more studies are necessary because literature is deficient in information about them.

Consumption of leafy vegetables is beneficial, however, the ingestion of contaminated food may cause diseases. The objective of this study was to obtain data on microbiological quality of leafy vegetables produced in the Fronteira Oeste region of Rio Grande do Sul. Samples of lettuce, cabbage leaf, arugula and a mixture of parsley and chive were collected, with quantification of total and thermotolerant coliforms by most probable number method and detection of Salmonella sp. using Petrifilm™ Salmonella Express System. A questionnaire was applied to understand the cultivation system of leafy vegetables used in the region: local, type of fertilizer, water source and surroundings.  Results showed high counts of coliforms ranging from 2.21 to 3.38 MNP/g for total coliforms and from 0.60 to 3.38 log MPN/g for thermotolerant coliforms, and 47% (n=16) of prevalence for Salmonella sp. In addition, 100% (n=8) of arugula, 85.7% (n=6) of parsley and chive, 75% (n=6) of cabbage leaf, and 60% (n=6) of lettuce samples were classified as improper for consumption, mainly in the municipalities of São Borja and Alegrete. The use of fertilizer considered organic and untreated water for irrigation and the presence of animals close to the production could be some of the factors involved in this type of contamination. Microbial contamination indicated unsatisfactory hygienic-sanitary quality, which emphasizes the need of good agricultural practices and good handling practices for leafy vegetables in order to reduce health risks to consumers.

Environmental factors and fertilization practices can affect the accumulation of nitrate in leafy vegetables. This research was carried out under an organic greenhouse, in the autumn - winter and spring production cycles, between 2007 and 2008 in Bajo Valle del Rio Negro, Patagonian Argentina. Various fertilizers with different doses were used, including composted bovine manure, onion-manure compost and commercial organic fertilizer. The accumulation of nitrate in leaves and petioles was evaluated. The concentration of NO-3 was related to temperature and incident solar radiation. The results indicate that organic production of spinach in the greenhouse is feasible in this region, in both crop cycles, keeping the nitrate content below the internationally established limits. The concentration of nitrate in spinach responded to the incident radiation with a correlation of -0.34 in spring and of -0.58 in autumn-winter. The highest contents were observed in periods of lower radiation during the autumn winter and lowest during spring.

Fruits and vegetables present losses after harvest. Practices that minimize respiration, transpiration and mechanical damage would increase their shelf life. The objective of this work was to evaluate post-harvest losses of Swiss chard, green onions, leeks, radish and rocket by the effect of the storage environment, hydration and material used for holding bunches during retail distribution, in autumn (May 30 to June 8, 2011). Storage environments: cold room (3.4 ºC, 97 % RH) and non-refrigerated environment (13 ºC, 81 % RH); Hydration: with and without immersion in chlorinated water on each day of measurement; Materials used for holding bunches: with Stipa sp. or tape. Variables evaluated on days 1, 3, 5, 7 and 9 after harvest were: weight loss by discard, loss or gain of weight by water, and total losses, in percentage. The experimental unit was the bunch with four replicates per treatment. A model of repeated measurements over time with MIXED procedure of SAS was used for the statistical analysis. The cold room storage produced less total loss (19.4 %) than the non-refrigerated environment (72.3 %). Losses in hydrated bunches were lower (37.3 %) than in non-hydrated ones (54.4 %). Bunches held with tape decreased discard in radish and total losses in leek. Cold room storage and hydration reduced post-harvest losses in Swiss chard, rocket, leek and radish.

The characteristics and the quality of vegetable crops during storage are influenced by the environmental conditions and the production technology. Some preharvest factors are closely bound and others act in an independent form. To provide high quality and value added to the product during the year, it is required high quality material and optimization in the different postharvest stages. Quality of vegetable product is affected by intrinsic factors, such as size, variety and maturation stage, like for extrinsic factors, temperature, processing, relative humidity and fresh-cut vegetable volume.

Mondino, M.C.; Ferratto, J.; Firpo, I.; Rotondo, R. Ortiz Mackinson, M.; Grasso, R. Calani, P. y Longo, A. 2007. Lettuce postharvest losses, at Rosario´s region, Argentine. Horticultura Argentina 26(60): 17-24.

The Fruithorticulture crisis is attributable, among other factors, to an inadequate postharvest. The objective of the work was the evaluation of postharvest losses and the identification of the main factors during harvest, handling and commercialization of the lettuce produced and marketed at Rosario’s Horticultural Belt. For the comparison of losses and their causes, a test for paired samples was used; for the different seasons, a Kruskal Wallis’s test, and for processes of handling the test of Wilcoxon and Kruskal Wallis. The losses were 21.2 % when arriving to the retailer and 19.05 % 24 hours later, totaling 40.25 %. Significant differences existed for damaged leaves when arriving to the retailer and for dehydrated leaves 24 hours later. In this stage, the damaged leaves and rusty stem were significantly higher in spring and for disease leaf in summer. Twenty four hours after harvest, differences in the three seasons were found for disease leaf, being significantly highest in summer. The losses for broken leaves and for rusty stem were higher when drip irrigation was used, the truck of the producer and retailer was not covered and when the period of time in parking area was more than three hours. The percentage of postharvest lettuce losses would justify the implementation of actions like covering trucks, and reducing the waiting time at wholesale markets parking areas.