Freezing - Articles and news items
Issue 5 2014 • 27 October 2014 • Christian James and Stephen J. James, Food Refrigeration and Process Engineering Research Centre, Grimsby Institute of Further and Higher Education
Frozen food is one of the largest sectors of the food industry and its value is increasing throughout the world. The frozen food market in seven of the major Western European Economies was valued at €83.51 billion in 2013 and is expected to grow in value by 10.89 per cent by 2016. The market is broadly segmented into frozen; vegetables and fruits, potatoes, ready meals, meat, fish/seafood and soup and more than 35 per cent of this market is in the frozen ready meals sector. In a previous article for New Food we discussed different innovative freezing technologies for foods. Apart from impingement, many of the technologies discussed are still in development. In this article we will look at proven technologies…
Issue 4 2012 • 6 September 2012 • Stephen J. James & Christian James, Food Refrigeration and Process Engineering Research Centre, Grimsby Institute of Further and Higher Education
Freezing is a well-established food preservation process that produces high quality nutritious foods that offer the advantage of a long storage life. However, freezing is not suitable for all foods and freezing does cause physical and chemical changes in many foods that are perceived as reducing the quality of the thawed material.
There is a general view that fast freezing, and the formation of small ice crystals, offers some quality advantages. However, this is not true of all foods. For example, while freezing rate may affect drip in meat there is no evidence that it has any substantial influence on its final eating quality. Nevertheless, many innovative freezing processes are currently being researched and developed across the globe to improve freezing times and product quality.
Some innovative freezing processes (impingement and Hydro-fluidisation) are essentially improvements of existing methods (air blast and immersion, respectively) that by providing far higher surface heat transfer rates than previous systems, aim to improve product quality through rapid freezing. In these cases, the advantages may depend on the size of the product, since the poor thermal conductivity of many foods limits the rate of cooling in large objects rather than the heat transfer between the cooling medium and the product.
Issue 4 2011 • 6 September 2011 • Lene Meinert, Consultant, Danish Meat Research Institute
Freezing is a well-known and widespread preservation method, prolonging the shelf-life of meat and many other food items. Freezing is popular, as it allows meat to keep a close-to-fresh quality for a long time, and it also allows long distance transports. However, depending on the time and temperature combinations during frozen storage, changes in meat quality can indeed occur. These changes include lipid oxidation, a major cause of deterioration of meat generating the undesired rancid taste and odour. It is important to note that freezing, which we use for food storage and distribution today, is not an infinite preservation method and quality reductions, made before freezing, do not disappear.
In order to understand which factors may affect the stability of pork during frozen storage, it is important to look at the composition of pork. Pork consists primarily of water, protein and fat, the proportion of the three vary greatly between the different cuts, some being more fatty e.g. pork belly than others e.g. pork loin. The composition of fat, or fat quality, has a huge influence on shelf-life and thereby also storage time, as the unsaturated fat content is prone to oxidation. Furthermore, pork also contains components that may promote oxidation such as iron. Finally, the amount of water influences the freezing process, as high water content requires increased freezing times.
Key driving forces for new foods are naturalness and nutrition. Consumers also expect pleasurable eating experiences. Unilever have recently launched “Frusi” , a completely new concept in ice cream that addresses the ‘enjoyment versus health’ paradox – the idea that something that tastes good cannot be healthy and vice versa. Moreover, Frusi is the first of a new generation of natural and nutritious pleasure-foods that is eaten directly from the freezer.
Issue 4 2007 • 16 November 2007 • Lars Reinholdt, Danish Technological Institute
Freezing and chilling are the most widespread conservation methods in the food production chain. Refrigeration is generally gentle but it can often influence the quality of food products. The International Institute of Refrigeration estimates that out of the total worldwide agricultural production (incl. fish and seafood) of 5,500 million tonnes a year, 1,800 million tonnes would benefit from refrigeration but only approximately 400 million tonnes are actually being refrigerated. This illustrates the importance of obtaining improved knowledge about the impact on food quality and the development of efficient refrigeration solutions.
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