The transport of water in four EVOH copolymers commonly used in high barrier food packages was characterized through permeation (continuous flow) and gravimetric experiments at different rela tive humidities and 23 ± 2°C. Water sorption isotherms were fitted with the D'Arcy and Watts' equa tion. From these data, the value of the solubility coefficient (S, as defined by Henry's law) was deter mined and was found constant within a 0.2-0.75 water activity (a w) range. Water uptake at the same a w increased as the EVOH ethylene content decreased. The permeability coefficient (P) for water through EVOH was determined as a function of water activity. The permeability was constant within the range of 0.3-0.75 a w and decreased with EVOH ethylene content. At high relative humidities (a w > 0.75) the value of permeability increased by up to two orders of magnitude. In this range, the higher the ethylene content the lesser the value of P.

Home Hydroponic Gardens. P Bradley & C Marulanda. Global Hydroponic Network. 2000. 240 pp.US$ 34.95 E 40.95 Contact GHN for price of mail, or details of distributors in Zimbabwe, Europe, Asia and Latin America GHN PO Box 151 Corvallis, Oregon 9

Growing food in little space is a challenge being faced daily by families in crowded areas. Hydroponics, the art of growing plants with no soil in water with added nutrients, is one solution but it has faced opposition from urban planners and scientists who stress that its complexity is beyond the normal woman or man. As the article on urban agriculture in Spore 81 urged, 'The scientist, whether based in a laboratory or a local community group, who develops a popular and transferable method of hydroponics will be remembered far into the next millennium for a significant contribution to food security.' Is Home Hydroponic Gardens the answer to the prayer? It could well be, with its rugged hard-cover full of careful and detailed texts and superb step-by-step coloured illustrations explaining how to use simplified hydroponics, requiring no mechanical devices. It gives methods and construction techniques for building hydroponic gardens on waste lots in towns, in backyards, on rooftops, with details of experiences in Zimbabwe, Senegal and Colombia. There are precise and proven recipes for the production of home-made organic nutrient mixes, as well as explanations of how plants take their nutrients and grow. This is real popular science at work, with dietary advice and recipes following the section on the daily chores of plant care and harvesting the dozens of suggested fruits, herbs, spices and salad, root and table vegetables. With a little bit of effort, a family with a hydroponic garden will not only end up healthier and wealthier, but also much better informed about how plants grow, and thus able to encourage the neighbours to take the hydroponic route too. Home Hydroponic Gardens. P Bradley & C Marulanda. Global Hydroponic Network. 2000. 240 pp.US$ 34.95 E 40.95 Contact GHN for price of mail, or details of distributors in Zimbabwe, Europe, Asia and Latin America GHN PO Box 151 Corvallis, Oregon 97339, USA Email: [email protected] | Home Hydroponic Gardens. P Bradley & C Marulanda. Global Hydroponic Network. 2000. 240 pp.US$ 34.95 E 40.95 Contact GHN for price of mail, or details of distributors in Zimbabwe, Europe, Asia and Latin America GHN PO Box 151 Corvallis, Oregon 9

This is a discussion of the issues surrounding water resource development and management in South Asia, namely, which innovative approaches and methodologies can help resolve the deadlock in water resources development and management?

Cet article est la synthese thematique d'une enquete menee recemment aupres de professionnels (industriels, fabricants et chercheurs) des industries alimentaires sur le theme de la reduction de la consommation d'eau et de la production d'effluents polluants, liee a ces operations. Sont presentees dans un premier temps, secteur par secteur, des donnees de consommations d'eau et de volumes d'effluents produits. Il apparait que de nombreuses procedures de travail et procedes de fabrication peuvent etre ameliores. La tendance doit aller vers une gestion de l'eau comme matiere premiere ou solvant recyclable faisant partie integrante de la rationalisation des procedes (economie d'eau, d'energie, de matiere). Cette gestion passe par la minimisation des rejets apres epuration, en particulier dans le cas de traitement des effluents, et le recyclage des flux aqueux et de matieres, soit directement dans le processus classique de fabrication, soit de facon degradee dans les processus connexes. De nombreux points d'amelioration sont precises et des axes de recherche sont proposes

A new model of water sorption isotherm is developed on the basis of Raoult's law. It is assumed that water present in food occurs in two states, as free water with properties of the bulk water and as water of hydration. Hydrated molecules are considered as new entities with molecular weights larger than those of non-hydrated molecules. Hydration reduces the free concentration of water and thus affects water activity in solution. Application of the developed equation to food sorption data showed that it gives approximation of sorption isotherms much better than that offered by the GAB model. Moreover, it predicts infinite adsorption at a(w)=1, the property which is not offered by the GAB equation. The new equation makes it possible to interpolate isotherms at high water activities close to one. The probability that the new equation will fit the food isotherm with small RMS is higher than 90% and substantially exceeds that found for the GAB model. As a two-parameter model it makes substantial improvement over the three-parameter GAB equation.