A starchy food that is initially a single-phase body turns into a multiphase body during boiling because of starch gelatinization. Fick's law is applicable only to a homogeneous system and is not applicable to such a multiphase system. Relative Water Content (RWC) model has been proposed as an alternative model that is able to describe water migration in multiphase food systems. In the RWC model, water migration is driven by the gradient of water content divided by the water holding capacity (WHC), m/m*. In this study a WHC profile (WHC plotted against water content with which starchy food is heat-treated) was assumed based on information concerning starch gelatinization. Using this WHC profile, the correlation between WHC profile and transient water content profile in a wheat flour dough slab during boiling was examined. A modified WHC profile was found to be applicable for describing certain characteristic features of the transient water content profile in a slab of wheat flour dough during boiling.

Given current demographic trends and future growth projections, as much as 60% of the global population may suffer water scarcity by the year 2025. The water-use efficiency techniques used with conventional resources have been improved. However, water-scarce countries will have to rely more on the use of non-conventional water resources to partly alleviate water scarcity. Non-conventional water resources are either generated as a product of specialized processes such as desalination or need suitable pre-use treatment and/or appropriate soil-water-crop management strategies when used for irrigation. In water-scarce environments, such water resources are accessed through the desalination of seawater and highly brackish groundwater, the harvesting of rainwater, and the use of marginal-quality water resources for irrigation. The marginal-quality waters used for irrigation consist of wastewater, agricultural drainage water, and groundwater containing different types of salts. in many developing countries, a major part of the wastewater generated by domestic, commercial, and industrial sectors is used for crop production in an untreated or partly treated form. The protection of public health and the environment are the main concerns associated with uncontrolled wastewater irrigation. The use of saline and/or sodic drainage water and groundwater for agriculture is expected to increase. This warrants modifications in the existing soil, irrigation, and crop management practices used, in order to cope with the increases in salinity and sodicity that will occur. It is evident that water-scarce countries are not able to meet their food requirements using the conventional and non-conventional water resources available within their boundaries. Another option that may help to achieve food security in these countries is the 'physical' transportation of water and food items across basins, countries, and regions. Long-distance movement of surface freshwater or groundwater and transporting the water inland via large pipelines or across the sea in extremely large bags are examples of 'physical' transportation. Most interregional water transportation projects are still in their infancy, though the trade of food items between countries has been going on since international trade began. Although food is imported in the international food trade, the water used to produce the food that is imported into water-scarce countries is equivalent to large water savings for those countries: without the imports, almost the same amount of water would be needed to produce that food domestically. The term 'virtual water' has been used to illustrate the important role that water plays in the trade in food between countries with a water surplus and those with a water deficit, which must rely in part on importing food to ensure food security. Because the major food-exporting countries subsidize their agricultural production systems, food-importing countries need to consider both the policies and political situations of food-exporting countries, while simultaneously using food trade as a strategic instrument to overcome water scarcity and food deficits. This paper reviews the literature and issues associated with the use of non-conventional water resources and opportunities for achieving food security in water-scarce countries. (c) 2006 Elsevier B.V. All rights reserved.

Apparent water diffusivity has been studied on an emulsified food model made of gelatin and hydrogenized vegetable fat. Lipid content was varied from 0 to 50% w/w and three particle mean diameters were generated (40, 110, and 400 mu m) in gelatin samples containing 75g of water per 100g of fat-free sample. In joined compartment experiments, fatty hydrated gels were dehydrated in contact with either a dry pure gelatin compartment or an industrial sponge cake. Water content profiles were used to determine the apparent water diffusivity value using Ruiz Cabrera et al.'s method,([1]) which takes gel shrinkage into account.

1. Growth and reproduction of Daphnia fed lake seston were measured in two categories of meso- to eutrophic lakes differing with respect to terrestrial organic matter influence (humic and clear water lakes). The content of highly unsaturated fatty acids (HUFA), P and N, as well as the taxonomical composition of seston were analysed. 2. Seston HUFA and C : P ratios were similar between lake categories, whereas C : N ratios were lower in the clear water lakes in both spring and summer. Despite the similarity in HUFA and P content of seston, Daphnia growth rate, clutch size and the proportion of gravid females were, respectively, about 1.5, 3 and 6 times higher in the clear water lakes. 3. Differences in growth and reproduction were related to a combination of higher N content and good fatty acid quality of the seston in the clear water lakes. Relatively high biomass of edible algae, such as Rhodomonas sp. and Cryptomonas sp., in the clear water lakes, and differences in water pH likely contributed to the observed differences in Daphnia growth and reproduction between lake categories. Additionally, it is possible that Daphnia was energy limited in the humic lakes despite high particulate organic carbon (POC) concentrations, as the contribution of non-algal and detrital C to the POC pool was high. 4. Our results suggest that dietary HUFA content has the potential to improve herbivore growth and reproduction if N and P are not limiting. N merits more attention in studies of zooplankton nutrition.