This book makes it possible for those interested in the water or food industry to understand better the causes of the concerns of environmentalists, and for the environmentalists to understand better the problems associated with the control of nitrate exposure with respect to decreased food production and possible wholesale changes in the appearance of the countryside.

Cold plasma is an emerging non-thermal disinfection and surface modification technology which is chemical free, and eco-friendly. Plasma treatment of water, termed as plasma activated water (PAW), creates an acidic environment which results in changes of the redox potential, conductivity and in the formation of reactive oxygen (ROS) and nitrogen species (RNS). As a result, PAW has different chemical composition than water and can serve as an alternative method for microbial disinfection.This paper reviews the different plasma sources employed for PAW generation, its physico-chemical properties and potential areas of PAW applications. More specifically, the physical and chemical properties of PAW are outlined in relation to the acidity, conductivity, redox potential, and concentration of ROS, RNS in the treated water. All these effects are in microbial nature, so the applications of PAW for microbial disinfection are also summarized in this review. Finally, the role of PAW in improving the agricultural practices, for example, promoting seed germination and plant growth, is also presented.PAW appears to have a synergistic effect on the disinfection of food while it can also promote seedling growth of seeds. The increase in the nitrate and nitrite ions in the PAW could be the main reason for the increase in plant growth. Soaking seeds in PAW not only serves as an anti-bacterial but also enhances the seed germination and plant growth. PAW could potentially be used to increase crop yield and to fight against the drought stress environmental conditions.

Nitric oxide has been suggested to be involved in the regulation of fluid and nutrient homeostasis. In the present investigation, vasopressin and nitric oxide metabolite (nitrite and nitrate) levels were determined in plasma of male Wistar rats submitted to water or food deprivation for three days. Hematocrit and plasma sodium showed marked increase in dehydrated and starved rats. Potassium levels and plasma volume decreased in both treated groups. Plasma osmolality and vasopressin levels were significantly elevated in water deprived (362.8±7.1 mOsm/kg H₂O, 17.3±2.7 pg/ml, respectively, p<0.001) rats, but not in food deprived (339.9±5.0, 1.34±0.28) rats, compared to the controls (326.1±4.1, 1.47±0.32). The alterations observed in plasma vasopressin levels were related to plasma osmolality rather than plasma volume. Plasma levels of nitrite and nitrate were markedly increased in both water and food deprived rats (respectively, 2.19±0.29 mg/l and 2.22±0.17 mg/l <i>versus</i>1.33±0.19 mg/l, both p<0.01). There was a significant negative correlation between plasma nitrite and nitrate concentration and plasma volume. These results suggest that both dehydration and starvation increase plasma nitric oxide, probably by activation of nitric oxide synthases. The release of nitric oxide may participate in the regulation of the alteration in blood flow, fluid and nutrient metabolism caused by water deprivation or starvation.

Luminescent Tb³⁺ functionalized metal–organic frameworks (MOFs) are prepared and act as food preservatives sensor and water scavenger for NO₂–. Classical metal–organic frameworks with uncoordinated N atoms in pores are elected as carrier to encapsulate Tb³⁺ ions. This Tb³⁺ incorporated material reveals excellent characteristic green luminescence of Tb³⁺ and good fluorescence stability in water. Subsequently, we choose this probe for sensing NO₂– among several food preservative compounds, showing a highly sensitive capability for detection of NO₂–; it is then proved that the Dexter energy transfer (DET) causes the luminescent quenching between Tb³⁺ and NO₂–, achieving the detection of NO₂–. This probe is also employed to detect the NO₂– in real water samples and act as water scavenger to remove the NO₂– in drinking water, showing a good removal capacity 3.45 mg (75.0 μmol) of NO₂– per gram of particles.

The synergistic antimicrobial effects of plasma-processed air (PPA) and plasma-treated water (PTW), which are indirectly generated by a microwave-induced non-atmospheric pressure plasma, were investigated with the aid of proliferation assays. For this purpose, microorganisms (Listeria monocytogenes, Escherichia coli, Pectobacterium carotovorum, sporulated Bacillus atrophaeus) were cultivated as monocultures on specimens with polymeric surface structures. Both the distinct and synergistic antimicrobial potential of PPA and PTW were governed by the plasma-on time (5&ndash;50 s) and the treatment time of the specimens with PPA/PTW (1&ndash;5 min). In single PTW treatment of the bacteria, an elevation of the reduction factor with increasing treatment time could be observed (e.g., reduction factor of 2.4 to 3.0 for P. carotovorum). In comparison, the combination of PTW and subsequent PPA treatment leads to synergistic effects that are clearly not induced by longer treatment times. These findings have been valid for all bacteria (L. monocytogenes > P. carotovorum = E. coli). Controversially, the effect is reversed for endospores of B. atrophaeus. With pure PPA treatment, a strong inactivation at 50 s plasma-on time is detectable, whereas single PTW treatment shows no effect even with increasing treatment parameters. The use of synergistic effects of PTW for cleaning and PPA for drying shows a clear alternative for currently used sanitation methods in production plants. Highlights: Non-thermal atmospheric pressure microwave plasma source used indirect in two different modes&mdash;gaseous and liquid; Measurement of short and long-living nitrite and nitrate in corrosive gas PPA (plasma-processed air) and complex liquid PTW (plasma-treated water); Application of PTW and PPA in single and combined use for biological decontamination of different microorganisms.

Slightly acidic electrolyzed water (SAEW) with available chlorine concentrations (ACC) of 35 and 70 mg/L is used instead of regular production water for soaking pea (Pisum sativum L.) seeds and spraying the sprouts during seed sprouting. Sodium hypochlorite (NaOCl) with the same ACC and tap water are used as a control in this study. The population of total bacteria, coliform, yeast and mold are determined at day 2, day 5, day 8, and day 11, respectively during seed sprouting. The biological indicators, nutritive indicators, and nitrite content after the sprouts are harvested are measured as well. The results indicate that when treated with SAEW, the counts of total bacteria, coliform, yeast and mold are reduced by 0.99–1.58 log CFU/g, 0.57–1.02 log CFU/g, and 1.01–1.22 log CFU/g respectively, compared to tap water treatment. Fresh weight, length, and edible rate of the sprouts significantly improve when treated with SAEW (p < 0.05). No evident adverse effects are observed in the nutritive indicators after SAEW treatment. In fact, a slight improvement (soluble sugar, flavonoid) was evident. Moreover, after a storage period of 7 d, the nitrite content of the sprouts was significantly lower in the SAEW treated samples than in any of other treatments. Therefore, SAEW could be a promising application in the production of pea sprouts to ultimately improve food safety.

Nitrite is a widely used food additive that has been shown to be carcinogenic and can cause health damage when consumed in excess. Therefore, developing a detection method is in demand. Here, we prepared a novel Fe-doped carbon dots (Fe-CDs) using metallic deep eutectic solvent (MDES) which showed high sensitivity and selectivity. Besides, it also showed excellent pH-dependent luminescence characteristics, which proved the feasibility as a pH sensor. Under the optimal conditions, the detection linear of nitrite ranged from 0.2 to 80 µM, and the detection limit was 50 nM. The recovery rate was between 98.8 % and 104.1 % in food and water samples. For pH monitoring, its fluorescence intensity was linearly correlated in the pH range from 2 to 7, accompanying a unique differential solution color change of colorless-yellow-green. Therefore, it can be used as an excellent fluorescent probe for detection of nitrite and pH in food and water environment.

Dietary exposure to nitrate and nitrite occurs via three main sources; occurrence in (vegetable) foods, food additives in certain processed foods and contaminants in drinking water. While nitrate can be converted to nitrite in the human body, their risk assessment is usually based on single substance exposure in different regulatory frameworks. Here, we assessed the long-term combined exposure to nitrate and nitrite from food and drinking water. Dutch monitoring data (2012–2018) and EFSA data from 2017 were used for concentration data. These were combined with data from the Dutch food consumption survey (2012–2016) to assess exposure. A conversion factor (median 0.023; range 0.008–0.07) was used to express the nitrate exposure in nitrite equivalents which was added to the nitrite exposure. The uncertainty around the conversion factor was taken into account by using conversion factors randomly sampled from the abovementioned range. The combined dietary exposure was calculated for the Dutch population (1–79 years) with different exposure scenarios to address regional differences in nitrate and nitrite concentrations in drinking water. All scenarios resulted in a combined exposure above the acceptable daily intake for nitrite ion (70 µg/kg bw), with the mean exposure varying between 95–114 µg nitrite/kg bw/day in the different scenarios. Of all ages, the combined exposure was highest in children aged 1 year with an average of 250 µg nitrite/kg bw/day. Vegetables contributed most to the combined exposure in food in all scenarios, varying from 34%–41%. Food additive use contributed 8%–9% to the exposure and drinking water contributed 3%–19%. Our study is the first to perform a combined dietary exposure assessment of nitrate and nitrite while accounting for the uncertain conversion factor. Such a combined exposure assessment overarching different regulatory frameworks and using different scenarios for drinking water is a better instrument for protecting human health than single substance exposure.