1 Preliminary investigations into the use of deepchill temperatures for prolonged storage of beef A. Small 1 , A. Sikes 1 & D. Doral 2 ¹Food Science Australia, PO Box 3312, Tingalpa DC, QLD 4173, Australia, E-mail: alison.small@csiro.au, anita.sikes@csiro.au. ²Meat and Livestock Australia, Locked bag 991, North Sydney, NSW 2059, Australia, E-mail: ddoral@mla.com.au. Abstract The limited storage life of vacuum packaged beef is often the major factor affecting the distribution chain and can limit the versatility and market penetration of this product. Storage temperature is usually limited to a minimum of -1.5°C to prevent the meat from freezing, and previous legislation in Australia defined chilled meat as being stored between -1.5°C and 4°C. The current legislation has no such prescription. Deep chilling, super chilling or partial freezing are terms used to describe the process of cooling a product to one or two degrees below its freezing point. It has been utilised with some muscle foods, particularly seafood, to extend the storage life of products. This study describes preliminary investigations into the effect of storage of beef at -2.5°C or -5°C on physical, microbiological and sensory aspects, as compared with beef stored at 0°C or -20°C. Beef stored at -2.5°C or -5°C demonstrates characteristics of frozen meat in terms of microbiology and drip loss. In addition, unsightly small white spots form on the surface of the cuts. Neither temperature would appear to be suitable for a deep chilling process aimed at maintaining the attributes of fresh meat. Introduction The limited storage life of vacuum packaged beef and lamb is often the major factor affecting the distribution chain and can limit the versatility and market penetration of these products. Storage temperature is usually limited to a minimum of -1.5°C to prevent the meat from freezing. Chilling has been identified by industry groups as a priority area for improvement. Customer requirements and anecdotal evidence from the industry suggests that storage lives of greater than the current expectations can be achieved, but there is no scientific evidence available for processors to use in validating the process. Previous legislation defined chilled meat as being stored between -1.5°C and 4°C, but the current legislation has no such prescription (Anon 2006; 2007a; b). Deep chilling, super chilling or partial freezing are terms used to describe the process of cooling a product to one or two degrees below its freezing point (Duun and Rustad 2007). It has been utilised with some muscle foods, particularly seafood, to extend the storage life of products (Chang et al. 1998, Sivertsvik et al. 2003; Olafsdottir et al. 2006; Rosnes et al. 2006; Duun & Rustad 2007). In some applications crust freezing occurs without any measurable effect on final product quality. In other cases a portion of the freezable water has been converted to ice. Ideally, formation of ice should be prevented or avoided with a muscle food in order to retain its inherent properties. Slow freezing can result in formation of large intracellular ice crystals that cause more damage to the muscle structure resulting in higher loss of drip on thawing and poorer water holding capacity (Grujic et al 1993, Petrovic et al 1993). There is some evidence that the formation of ice crystals in meat at sub-freezing temperatures can be inhibited by the application of agents that prevent nucleation of crystals. Vacuum packaging alone may be sufficient to prevent freezing at slight sub-freezing temperatures (Eustace and Bill 1988). This paper covers some preliminary investigations into the effect of storage of beef at temperatures just below 0°C (namely -2.5°C or -5°C) on physical, microbiological and sensory aspects, as compared with beef stored at 0°C or -20°C.