Last week, the ENOUGH project held two successful webinars showing results from some of our demonstrators. All presentations are available here (LINK).
On Monday (5 December) the webinar “Advancements in freezing technology for a sustainable food chain” took place. Several food products are perishable and highly depending on temperature control, which is energy intensive. This is why several of our demonstrators are focusing on freezing technologies.
- In Demo 15 (LINK), we are working with a brine freezer. The brine solution lowers the freezing point, and has the benefit of a great heat transfer efficiency. The main motivation for the brine freezing technology is the energy efficiency. The idea is to pre-freeze fish in brine before entering the freezing tunnel, which will save time and energy. One challenge is related to logistics. As frozen mackerel should fit in to a 20 kg box, the flexibility of the fish is important, i.e. it should not be frozen to a point where it becomes stiff. At the MMC First Process facility, several experiments have been conducted to monitor the effect of temperature and brine on the stiffness of mackerel. Other experiments have involved brine freezing of salmon, where one challenge is related to perceived quality, as the brine has shown to alter the colour of the fish.
- In Demo 18 (LINK), using ultra-low temperature blast freezing, the objective is to develop a refrigeration unit with high efficiency that guarantees significant energy savings and use of natural refrigerants. The freezing is achieved by exposing the product to extremely low temperatures to reduce the time required for freezing. The schematic diagram and technical details of the prototype was presented. A numerical model of the demonstrator unit has been developed and used to map the performance of the unit, diagnose problems, and optimise parameters. This model is currently being validated against experimental results at different conditions.
- Demo 12 (LINK) is about long-term food storage using freeze drying. This is a way of preserving the food while maintaining the nutritional quality. The challenges are that it is energy and time consuming. Improving the energy efficiency can reduce the GHG emissions of the process. The process of freeze drying was presented. This demonstrator will improve the freeze drying technology by basing the system on natural refrigerants. Applying vacuum freezing at the first stage of the process will reduce freezing and sublimation time. The unit will be in a domestic scale suitable for household applications. So far, experiments have been done using potato slices and raspberries. The results show that the cooling rate is about five times higher compared to a standard freeze dryer.
The next webinar, “How to improve the sustainability of the food chain?” took place on Thursday 7 December. Selected demonstrators were presented to show how to reduce emissions in several steps of the food chain: storage, packaging, transport and retail.
- Demo 5 (LINK) of the ENOUGH project is demonstrating how modifying the atmosphere of a fruit storage will delay the quality deterioration. The level of oxygen in the storage is important to balance; too high oxygen levels can lead to discoloration of the skin, while too low oxygen levels will create an internal browning and off-flavours of the fruit. The dynamic controlled atmosphere (DCA) makes us able to monitor respiration due to sensor technology. As the fruit respirates, oxygen levels go down and CO2 is being produced. The experiments have shown that the quality is retained during long-term storage and energy savings compared to standard CA is at about 15%, due to less cooling for respiration heat and less CO2
- Demo 6 (LINK) explores climate neutral food packaging. Perishable foods like fruit have a very high percentage of loss through the food chain. In Europe, we have high food waste at the consumption/household level. Packaging has several roles like display the product, protect fruits against the environment and increase the shelf life. However, packaging also creates waste. Using sustainable packaging materials can reduce emissions by replacing wasted packaging by sustainable alternatives. Optimised packaging solutions can reduce food waste and save energy by reducing refrigeration needs. This demonstrator is looking at the viable materials with the right material compatibility (technical and food wise).
- One big source of emissions occurring in several parts of the food chain is transport. This is being tackled in Demo 7 (LINK), “fresh and green delivery”. Refrigerated transport is key to preserve the cold chain and avoid food loss. The current refrigeration units are not optimised, presenting low efficiency (considering energy and logistics) and using synthetic refrigerants with high global warming potential. That is why this demonstrator is developing a transportation unit with higher efficiency, flexibility in temperature range, natural refrigerants, electrical vehicle, and renewable energy sources. The demo is working on system configurations, ejector design and performance, numerical modelling to develop a dynamic numerical model of the cooling unit.
- Demand-side response (DSR) is a tool to manage intermittency of energy sources. Refrigerating equipment with energy storage in the food supply chain have the potential to be used for DSR. In Demo 11 (LINK), the DSR technology is demonstrated in the retail sector for a display cabinet with closed doors. The technology is a thermal storage unit in a refrigerating equipment for DSR. Direct heat transfer between the refrigerant and PCM (phase changing material) is enabled, increasing the efficiency. The prototype is built in a laboratory and testing is ongoing. Next step will be to build a field prototype, currently under design.
