PR | IFPRI3; ISI; CRP5 | EPTD; MTID | CGIAR Research Program on Water, Land and Ecosystems (WLE)

The world economy is under pressure for greater, more efficient and more sustainable use of natural resources to meet complementary and competing objectives in the food, water and energy sectors. Interactions between these three sectors have become increasingly affected by the bioeconomy—a concept that encompasses economic growth driven by the development of renewable biological resources and biotechnologies to produce sustainable products, employment and income. This article explores how water and the bioeconomy are interlinked, including how the constraints from growing water scarcity—in part caused by development of the bioeconomy—may influence bioeconomic growth. The article describes the impact of biofuel production on water quantity and quality and examines the potential for improved water use through the development of crop biotechnology and improved crop management. Then alternative scenarios for water in the bioeconomy are assessed, and policy conclusions are presented.

Pulsed-field gradient NMR (PFG-NMR) is being widely applied to probe living tissues and biological cells structure for measurement of thermodynamic binding constants, membrane permeability and rate of transmembrane exchange processes. Water movements in biological systems and food matrices are important in the engineering aspect such as quality manipulation in food processing. The measurement of diffusion properties of water molecules in food systems is now possible using PFG-NMR, and the hydration properties and hydrodynamic properties of food materials can be accurately evaluated by this method.

Pulsed-field gradient NMR (PFG -NMR) is widely applied to probe living tissues and biological cells structure for measuring thermodynamic binding constants, membrane permeability and rates of transmembrane exchange processes. Water movements in biological systems and food matrices are important in the engineering aspect such as quality manipulation in food processing. The measurement of diffusion properties of water molecules in food systems is now possible using PFG -NMR, and the hydration properties and hydrodynamic properties of food materials can be accurately evaluated by this method. In this paper, we measured the diffusion behavior of water in protein matrix, Tofu, and the membrane permeability in biological cell such as chlorella, yeast and human red blood cell non-invasively by PFG-NMR.

When a starchy food such as a rice grain or a strand of noodle is boiled, a high moisture region is generated at the surface spreading inward, producing a low moisture core. The characteristic features of the change of moisture profile were recently observed by nuclear magnetic resonance imaging (MRI). However, the profile cannot be described by any existing mathematical model based on the principle that water molecules are driven by the gradient of moisture content. In this paper, a new mathematical model is proposed using a new concept, water demand (WD). In this model, migration of water is driven by the gradient of WD, which is defined as the difference between the ceiling moisture content and the existing moisture content. This model is demonstrated to have a potential to describe the characteristic features of the change of moisture profile in starchy food during boiling.

The consequences of humidity exchanges between food and environment are always very important for the preservation of microbiological and sensorial quality of the product. For a realistic shelf-life evaluation of sensitive food-products is therefore essential to know exactly the water vapour transmission rate (WVTR) through the packaging material. The measurement of this important diffusional property is commonly performed without regard of the exchange direction and in conditions very far from those of reality: extremes temperature and humidity combinations as 38 deg C and 90% of RU. Thus, it was considered useful and interesting to verify if the permeability phenomenon could be affected by the direction of flow and by the contact of dry or moist product. To such purpose, measures of water vapour permeability were realized using PET and OPP pouches, filled with water or calcium chloride. The results achieved excluded the influence of the contact of dry or wet substances with the pouches walls and of the flow direction on the determination of the WVTR for the materials and the conditions examined | Le conseguenze di uno scambio di umidita' tra alimento ed ambiente risultano sempre molto importanti per la conservazione della qualita' biologica ed organolettica del prodotto. Per una reale valutazione della conservabilita' dei prodotti alimentari sensibili all'umidita' e' quindi essenziale conoscere la velocita' di trasmissione al vapore acqueo (WVTR) attraverso il materiale di confezionamento. I metodi convenzionali di misura di questa importante proprieta' diffusionale sono solitamente riferiti a condizioni lontane da quelle reali sia per le combinazioni temperatura-umidita' relativa in cui si effettuano le determinazioni (38 gradi C e 90% di UR), sia per quanto riguarda le modalita' in cui il fenomeno di permeazione avviene. Non si tiene infatti in considerazione ne' la direzione di flusso del vapore d'acqua, ne' che nel caso reale il prodotto (umido o secco) si puo' trovare a diretto contatto con il materiale. Si e' cosi' ritenuto importante poter verificare se il fenomeno di permeabilita' fosse influenzato da queste condizioni e dalla direzione del flusso. A tal fine si sono effettuate misure di permeabilita' impiegando buste realizzate con PET ed OPP, riempite con acqua o cloruro di calcio. I risultati ottenuti hanno escluso l'influenza del contatto e della direzione di flusso sulla determinazione della WVTR per i materiali e le condizioni considerate

Nylon 6 and nylon 12 food packaging materials used as sausage casings are typically exposed to fatty food on one side and boiling water on the other during the cooking process. To simulate the migration behaviour under these conditions, a special migration cell was constructed and filled with olive oil on one side of the polymer and water on the other to find out what amounts of the migrants will transfer to either side and phase at 100 °C. Results show that when a nylon 6 film is exposed to the conditions as described above, total mass transfer of the monomer—caprolactam—into the water phase occurs after 2 h at 100 °C. Nylon 12 sausage casings release similar amounts of their monomer—laurolactam—into both the aqueous and oil phase. An existing computer migration model was adapted to simulate the situation of simultaneous two-sided migration applying previously determined diffusion and partitioning coefficients. The suitability of the model was confirmed by experimental data.

This paper reports on the development of an approximate empirical-CFD modelling procedure combining experimental correlations for the heat and mass transfer coefficient determination and specific user-defined functions (UDF) implemented in the commercial CFD code Fluent to simulate the interrelationships at play between airflow and transfers of unwrapped food products bathing in air. Transfer modelling required specific calculation to account for water evaporation from the product surface. Mean transfer coefficients at the air-product interface were determined empirically from validated experimental correlations, where the CFD mean air velocity that is calculated in a small user-defined volume surrounding the product was incorporated. Internal water diffusion was taken into account by considering the product as a motionless fluid composed of dry matter and water. The procedure developed allows, in a single CFD calculation using a single mesh, temperature and water concentration fields to be computed and the water loss kinetics of the products to be determined together with the temperature and relative humidity fields of the air flowing around them. Although the established procedure was set up with the aim of assessing heat and water exchanges occurring in large stacks of unwrapped food products subjected to airflow, this last was validated for modelling, first, one-dimensional drying of a meat cylinder and second, three-dimensional drying of five cylindrical plaster casts placed in a row. Its application to the ripening of a row of six cheeses is also discussed.