Carcass chilling in Australian abattoirs

Summary

Chilling or freezing is a critical step in the processing of carcases. It is energy intensive, and correct chilling and freezing regimes are important in optimising eating quality.

This project set out to survey seven abattoirs in Queensland and New South Wales. Chiller design factors including room dimensions and cooling unit data were measured, as well as performance metrics such as deep meat temperatures and weight loss, for different chilling procedures.

Objectives

This project set about to provide information on the design, operation and performance of batch chillers in used in the Australian red meat industry and report on those which are most effective for specific use cases in the industry.

Key findings

• Preliminary tests showed that cooling conditions varied widely from place to place in a batch chiller and from time to time throughout the chilling cycle.
• Batch chillers were not of a standard design but varied widely in dimensions and carcass capacity. The type, cooling capacity and location of units varied in each installation.
• In 5 out of 7 test chillers, air temperatures in the vicinity of test carcasses varied from place to place in the chiller, and air velocities varied from 0 to 3m/s. Non-uniform air distribution, leading to non-uniform cooling rates, resulted from inadequacies in the design and location of cooling units.
• Chiller temperature control was generally unsatisfactory, mainly due to thermostat location in zones of poor air circulation or close to hot or cold surfaces.

Benefits to industry

Chilling is of great importance to the red meat industry because it minimises the growth of meat spoilage organisms. Good chilling practices are essential if meat is to be stored satisfactorily over long periods.

In addition, procedures adopted for cooling freshly killed carcases are known to affect certain quality attributes of meat, such as tenderness and bloom, and to influence weight losses by evaporation and drip. The project will further the knowledge of chillers in Australian abattoirs and their potential of having positive impacts on red meat products.

MLA action

The scoping study P.PSH.0557 estimated the potential value proposition for lamb processing plants by implementing automated carcase handling into and out of chillers using RFID traceability. Automated carcase handling is not a new idea. However, existing sorting systems do not provide individual carcase traceability, nor do they provide the enabling platform required to utilise other existing technologies that can improve supply chain profit.

Under project P.PSH.0186, MLA co-funded Australia’s first industrial refrigeration system utilizing Carbon Dioxide (CO²) refrigerant for freezing cartoned meat in a fully automatic mechanised carton freezing tunnel, as well as the associated frozen and chilled storage and sorting and loading areas. Realcold Milmech Pty Ltd, working with meat industry consultant and project manager Meateng, designed, installed and commissioned this ambitious, innovative and energy efficient system utilizing a CO² ammonia cascade refrigeration system and a Realcold automatic air blast carton freezing tunnel.

Prior to 2005, numerous studies and fact sheets were created by MLA's predecessors as well as CSIRO. These are shown as attached reports starting with REF project codes. In project MRR.296 (1996), the relative advantages of small capacity plate and air blast freezers for the freezing of cartoned meat were investigated.

P.PSH.0476 Chiller Shrink Project at Teys Beenleigh. The key objective of this project was to determine the level of chiller shrink at the Teys Beenleigh site as there was a perception that there are quantities of shrink which could be potentially reduced. Accurate measurements needed to be taken in order to establish if work is required with the refrigeration process at Teys Beenleigh. This project with the assistance from MLA would give a definitive result on what shrink is occurring to the carcasses whilst in the chillers, from this decisions could be made as to if the shrink is at an acceptable level or if changers needed to be made. However, it was concluded that the results were not enough to determine the true performance of the Beenleigh chillers.

Future research

In a special test of ‘ultra-rapid’ chilling cycle (using very cold air circulating at high velocity for the first 3hrs of the cycle, with no further cooling for the remainder of the cycle), deep meat temperatures were reduced to 10C or lower in 20hr chilling.

Weight loss was 1.5% and surface fat was soft enough for boning operations. The ‘ultra-rapid’ chilling conditions could be used as the basis for a continuous tunnel chilling procedure and it is suggested a industry partner be identified to trial this method in a commercial setting.