Sustainable and integrated management of water, energy, food, and ecosystems requires a coordinated and cross-sectoral approach to manage trade-offs and maximize synergies among these deeply interconnected resources. This line of action is called the water-energy-food-ecosystem (WEFE) nexus approach. This 5-day course provides an overview of WEFE nexus concepts, issues, and approaches to develop the capacities of early- to mid-career professionals in any WEFE or WEFE-adjacent sector, to foster the integrated, equitable, and sustainable management of WEFE resources. This course was co-developed under the umbrella of the CGIAR Initiative on NEXUS Gains by the Center for Water Resources Studies (CWRS), Institute of Engineering, Tribhuvan University, in partnership with the Alliance of Bioversity international and CIAT, and the International Water Management Institute (IWMI). It includes theory as well as practical applications and interactive elements.

Exploring the environmental impact of dietary consumption has become increasingly important to understand the carbon-water-food nexus, vital to achieving UN sustainable development goals. However, the research on diet-based nexus assessment is still lacking. Here, we developed an Environmentally Extended Multi-Regional Input-Output (EE-MRIO) model with compiling a global MRIO table based on the latest Global Trade Analysis Project (GTAP) 10 database, where we specifically constructed a water withdrawal account and matched it to each economy at the sectoral level. The regional heterogeneity and synergy of carbon-water nexus affected by dietary patterns in nine countries was explored. The results show that: (1) Dietary consumption is the main use of water withdrawal for each country; Japan, the US, South Korea, and India have a high per capita dietary water footprint. Mainly due to consumption of processed rice, Japan has the highest per capita value of 488 M³/year, accounting for 63.4% of the total water footprint. (2) The total dietary carbon footprints in China, India, and the US are high, which is mainly caused by the high consumption of animal products (including dairy) either due to the large population (China, India) or animal-based diet (the US). Americans have the highest per capita dietary carbon footprint, reaching 755.4 kg/year, 2.76 times that of the global average. (3) Generally, imported/foreign footprints account for a greater share in dietary water and carbon footprints of developed countries with an animal-based diet. (4) In the nexus analysis, the US, Japan, and South Korea are key-nexus countries, vegetables, fruit and nuts, tobacco and beverages, and other food products are selected as key-nexus sectors with relatively high dietary water and carbon footprint. Furthermore, dietary consumption choices lead to different environmental impacts. It is particularly important to find a sustainable dietary route adapted to each country considering that heterogeneity and synergism exist in key-nexus sectors to achieve the relevant Sustainable Development Goals.

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.

Strong acidic electrolyzed water (SAcEW) is generated by using a diaphragm type electrolytic cell and adding a small amount of salt solution to the tap water. The acidity of this water causes chloride ions, as the major factor in sterilization process, to form hypochlorous acid. Therefore, it is said that the sterilization time with SAcEW is shorter than with sodium hypochlorite generally used for food sterilization. After being registered as a food additive (2002) in Japan, SAcEW began to be used for washing food in food processing facilities in order to improve the food sterilization level. In this research, the possibility of an enhanced sterilization effect of SAcEW generated by a water electrolyzer was evaluated by adding physical washing methods (ultrasonic, stream overflow, bubbling) and pre-washing with strong alkaline electrolyzed water (SAlEW) which is generated at the same time. As a result, the combination with pre-washing with SAlEW was found to be less effective than washing with SAcEW only when comparing the same washing time. As for the supplementation of physical washing methods, the stream type was found most effective. In addition, comparison between the sodium hypochlorite treatments (200 mg/L, soaked for 5 minutes) recommended by the Japanese Ministry of Health, Labor and Welfare for raw food materials and the SAcEW treatment for 10-30 seconds suggested equivalent sterilization effects on raw food materials.

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 (5–50 s) and the treatment time of the specimens with PPA/PTW (1–5 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—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.

Despite the progress in the area of food safety, foodborne diseases still represent a massive challenge to the public health systems worldwide, mainly due to the substantial inefficiencies across the farm-to-fork continuum. Here, we report the development of a nano-carrier platform, for the targeted and precise delivery of antimicrobials for the inactivation of microorganisms on surfaces using Engineered Water Nanostructures (EWNS). An aqueous suspension of an active ingredient (AI) was used to synthesize iEWNS, with the ‘i’ denoting the AI used in their synthesis, using a combined electrospray and ionization process. The iEWNS possess unique, active-ingredient-dependent physicochemical properties: i) they are engineered to have a tunable size in the nanoscale; ii) they have excessive electric surface charge, and iii) they contain both the reactive oxygen species (ROS) formed due to the ionization of deionized (DI) water, and the AI used in their synthesis. Their charge can be used in combination with an electric field to target them onto a surface of interest. In this approach, a number of nature-inspired antimicrobials, such as H₂O₂, lysozyme, citric acid, and their combination, were used to synthesize a variety of iEWNS-based nano-sanitizers. It was demonstrated through foodborne-pathogen-inactivation experiments that due to the targeted and precise delivery, and synergistic effects of AI and ROS incorporated in the iEWNS structure, a pico-to nanogram-level dose of the AI delivered to the surface using this nano-carrier platform is capable of achieving 5-log reductions in minutes of exposure time. This aerosol-based, yet ‘dry’ intervention approach using iEWNS nano-carrier platform offers advantages over current ‘wet’ techniques that are prevalent commercially, which require grams of the AI to achieve similar inactivation, leading to increased chemical risks and chemical waste byproducts. Such a targeted nano-carrier approach has the potential to revolutionize the delivery of antimicrobials for sterilization in the food industry.

AIMS: To evaluate synergetic effect of slight acidic electrolysed water (SAEW) and fumaric acid (FA) on inactivation of total viable count (TVC) and Staphylococcus aureus, Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella Typhimurium in fresh beef and to study shelf life and sensory quality of beef. METHODS AND RESULTS: Inoculated samples was dipped for 1, 3 and 5 min and immersed at 25, 40 and 60°C in SAEW, strong acidic electrolysed water (StAEW) and SAWE + FA. Treated meat was air‐packaged and stored at 4 or 10°C. During storage, sampling was performed at 2‐day intervals for microbiological and sensory changes. TVC was decontaminated at 40°C for 3 min by more than 3·70 log CFU g⁻¹, and examined pathogens were reduced by more than 2·60 log CFU g⁻¹with SAEW + FA treatment. This treatment prolonged shelf life of beef meat up to 9 and 7 days when stored at 4 and 10°C, respectively. CONCLUSION: The combined treatment of SAEW + FA showed greater bactericidal effect and prolonged shelf life compared with individual treatments. SIGNIFICANCE AND IMPACT OF THE STUDY: Combined treatment of SAEW and FA can be a suitable hurdle technology reducing bacteria in fresh beef, substantially enhancing their microbial safety and decreasing pathogens growth during storage.

We report on high-internal-phase, oil-in-water Pickering emulsions that are stable against coalescence during storage. Viscous, edible oil (sunflower) was emulsified by combining naturally derived cellulose nanocrystals (CNCs) and a food-grade, biobased cationic surfactant obtained from lauric acid and L-arginine (ethyl lauroyl arginate, LAE). The interactions between CNC and LAE were elucidated by isothermal titration calorimetry (ITC) and supplementary techniques. LAE adsorption on CNC surfaces and its effect on nanoparticle electrostatic stabilization, aggregation state, and emulsifying ability was studied and related to the properties of resultant oil-in-water emulsions. Pickering systems with tunable droplet diameter and stability against oil coalescence during long-term storage were controllably achieved depending on LAE loading. The underlying stabilization mechanism was found to depend on the type of complex formed, the LAE structures adsorbed on the cellulose nanoparticles (as unimer or as adsorbed admicelles), the presence of free LAE in the aqueous phase, and the equivalent alkane number of the oil phase (sunflower and dodecane oils were compared). The results extend the potential of CNC in the formulation of high-quality and edible Pickering emulsions. The functional properties imparted by LAE, a highly effective molecule against food pathogens and spoilage organisms, open new opportunities in food, cosmetics, and pharmaceutical applications, where the presence of CNC plays a critical role in achieving synergistic effects with LAE.