This study was conducted in styrofoam trays placed on an aerated nutrient solution in vats in order to determine the effect of different nutrient solutions on rocket plant growth, yield and quality. Seeds of Bengi F1 rocket cultivar were sown into peat as inserting each seed to each hole (17 ccs) of trays with 210 cells (957 plant m-2). Following germination in the germination chamber, seedling trays were moved to a climate controlled greenhouse for adaptation. After emergence, the seedlings were transferred to water culture. The nutrient solution was applied as “full dose” (mg/L: N 150, P 50, K 150, Ca 150, Mg 50, Fe 5.0, Mn 0.50, Zn 0.05, B 0.50, Cu 0.03, Mo 0.02), “half dose” (macro elements reduced by 50%) and “without nutrients” (water). Cultivation was performed in 2 consecutive periods and in each period 3 harvests were done and quality analysis was done on the leaves from the first harvest. Results were given as the mean of two periods. Results showed that plant growth, yield and quality parameters vary depending on the concentration of the nutrient solution. It was observed that as the concentration of nutrient solution decreased, plant growth, biomass, yield values decreased, leaf color and total chlorophyll concentration did not change and while nitrate content decreased, vitamin C content increased. Leaf N, P, K and Fe element contents decreased with half dose, whereas Ca and Mg content did not change. However, there was no statistical difference between full dose and half dose treatments in many measured parameters. When all the data obtained from the study are evaluated together; it is suggested that rocket can be grown in a floating water culture and the dose of macro elements as reduced 50% can be preferred because it reduces the nitrate content, increases the vitamin C content and allows the use of less fertilizers without causing any significant reduction in yield compared with full dose.

In our study, validation was carried out at 24 and 200 mg/kg enrichment for residue analysis of nitrate active substance only in lettuce samples. Analyses were performed by using high performance liquid chromatography (HPLC) in lettuce, spinach, salad and arugula samples. In order to eliminate the matrix effect, matrix calibration was used, ie calibration of lettuce samples. Validation of the method was performed with criteria such as precision, repeatability, repeatability limit, reproducibility, repeatability limit, accuracy, linearity of calibration and recovery. The calibration curve was found as linear in the range of 0.2-40 mg/kg. The recovery from the samples is between 97.3-100.2 %. The repeatability and reproducibility values for the two concentrations were 1.89 (matrix+24 ppm) and 3.65 (matrix+200 ppm), 3.951 (matrix+24 ppm) and 3.456 (matrix+200 ppm), respectively. The repeatability and reproducibility limit values are within acceptable limits. Accuracy, precision, combined uncertainty and extended uncertainty (95% confidence: k=2) were found as 0.015 (matrix+24 ppm) and 0.004 (matrix+200 ppm), 0.039 (matrix+24 ppm) and 0.006 (matrix+200 ppm), 0.041 (matrix+24 ppm) and 0.007 (matrix+200 ppm), 0.082 (matrix+24 ppm) and 0.014 (matrix+200 ppm). In our study, the highest nitrate ratio was determined in spinach with 3486 mg/kg in total 102 samples. Lettuce following spinach (2825 mg/kg) showed lower nitrate content, while lower concentrations of nitrate were detected in iceberg (1985 mg/kg) and arugula (1870 mg/kg), respectively. The results may be useful in estimating body intake levels for research on the effects of nitrite and nitrate on human health in vegetable producers and in our daily diet. In addition, the nitrate content of the vegetables analysed in the study is an indicator of the use of nitrogenous fertilizers in the Mediterranean region, but showed no problem for human and animal health.

Nowadays, consumer demand for healthy and natural food is reflected in the meat industry and researches and investments on this issue have gained speed. Nitrite is a widely used synthetic additive in meat products due to its contribution to the development of characteristic color and flavor, controls lipid oxidation and has an antimicrobial effect on pathogenic microorganisms, especially Clostridium botulinum. However, the fact that nitrite causes the formation of toxic, mutagenic and carcinogenic N-nitrosamine compounds and constitutes a risk to human health has led to the searches for alternative additives. An important part of the studies on this subject consists of testing the use of natural additives as an alternative to nitrite. In recent years, instead of using nitrate and nitrite in meat products, studies have been carried out to use organic acids and microbial resources. In addition to these methods, up-to-date technology applications such as high pressure, irradiation, encapsulation, active packaging containing nitrite, zinc protoporphyrin IX compound formation and cold plasma technology constitute other research areas that we encounter in reducing the nitrite rate in meat products. Within the scope of this review, the functions of nitrite in cured meat products, current potential methods for reducing nitrite content and the limitations of transferring these methods to industry were examined.