The formation of stable transparent nanoemulsions poses two challenges: the ability to initially create an emulsion where the entire droplet size distribution is below 80 nm, and the subsequent stabilization of this emulsion against Ostwald ripening. The physical properties of the oil phase and the nature of the surfactant layer were found to have a considerable impact on nanoemulsion formation and stabilization. Nanoemulsions made with high viscosity oils, such as long chain triglycerides (LCT), were considerably larger ( D = 120 nm) than nanoemulsions prepared with low viscosity oils such as hexadecane ( D = 80 nm). The optimization of surfactant architecture, and differential viscosity eta D/eta C, has led to the formation of remarkably small nanoemulsions. With average sizes below 40 nm they are some of the smallest homogenized emulsions ever reported. What is more remarkable is that LCT nanoemulsions do not undergo Ostwald ripening and are physically stable for over 3 months. Ostwald ripening is prevented by the large molar volume of long chain triglyceride oils, which makes them insoluble in water thus providing a kinetic barrier to Ostwald ripening. Examination of the Ostwald ripening of mixed oil nanoemulsions found that the entropy gain associated with oil demixing provided a thermodynamic barrier to Ostwald ripening. Not only are the nanoemulsions created in this work some of the smallest reported, but they are also thermodynamically stable to Ostwald ripening when at least 50% of the oil phase is an insoluble triglyceride.

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Purpose Water use in the livestock sector has featured in the debate about sustainable food systems. Most evidence has come from virtual water calculations which lack impact assessment and adequate consideration of the heterogeneity in livestock production. This study sought new evidence, using a recently developed life cycle impact assessment method for water use to assess six geographically defined beef cattle production systems in New South Wales, Australia, a major production region. Methods The livestock production systems were diverse in farm practice (grass and feedlot finishing), product (yearling to heavy steers), environment (high-rainfall coastal to semi-arid inland) and local water stress. Life cycle inventories were developed from representative farm enterprise budgets. The farm water use inventories sought to describe the impact of the production system on catchment water resources and included irrigation water use as well as the reduction in flows due to the operation of stock dams. Results and discussion The normalised life cycle impact category results for water use, referred to as the water footprint, ranged from 3.3 to 221 L H 2 Oe kg −1 live weight at farm gate. Due to variation in local water stress, the impact category results were not correlated with the inventory results. Conclusions The substantial variability in water footprint between systems indicates that generalisations about livestock and livestock products should be avoided. However, many low input, predominantly non-irrigated, pasturebased livestock production systems have little impact on freshwater resources from consumptive water use, and the livestock have a water footprint similar to many broad-acre cereals. Globally, the majority of beef cattle are raised in non-irrigated mixed farming and grazing systems. Therefore, the general assertion that meat production is a driver of water scarcity is not supported.