Alternative methods of Applying Extra Low Voltage Electrical Stimulation

Summary

Research has shown that the single greatest contribution to variability in meat eating quality occurs during processing. Therefore, starting in 2002, MLA undertook R&D in parallel with the MSA and SMEQ programs to develop processing intervention electronics technologies through the Meat Quality Science and Technology (MQST) program. This program was co-funded with Meat & Wool New Zealand via the MLA Donor Company.

Generation One technologies

To address the quality variation that occurs during sheep and beef processing, MLA developed a suite of computer-controlled processing intervention technologies. These technologies were based on new forms of electronics that maximise both eating quality and processing efficiency. The initial development of the sheep technologies was completed in 2002 and the beef technologies in 2003. The suite of technologies that comprised the Generation One electronics is summarised below.

• Controlled Dose Low Voltage Stimulation (beef and sheep): to control meat tenderness.
• Electronic Bleeding (beef): to enhance blood yield, improve meat colour, improve plant hygiene and reduce costs.
• Low Frequency Carcase Immobilisation (beef and sheep): to reduce OHS risk. Imparts a small stimulation effect.
• High Frequency Carcase Immobilisation (beef and sheep): to reduce OHS risks. No stimulation effect.
• Mid Voltage Electrical Stimulation (beef and sheep): to control meat tenderness.

The above Generation One electronics was to be controlled by an overarching management system called the Computer Process Management System (CPMS) which was to regulate their operation based on operator defined parameters. These parameters were to based on the normal characteristics of the type of animals being processed in a batch, taking into account factors such age, sex, and husbandry.

However, this was never implemented owing to the cost, complexity and technical limitations in developing centralised process control of eating quality within a processing plant.

Generation One technology was to be replaced by a more sophisticated, carcase specific, stimulation system (SmartStim) but further work on this has been discontinued. See the SmartStim summary for more information.

Early Research (1970-2000)

Some early research was carried out in the 1970's and1980's on electrical stimulation and immobilisation, but this did not lead to widely available, commercial systems.

Project report 0581 outlined the test work undertaken on a high voltage stimulation unit that had been designed and installed on a commercial beef slaughter floor.

The objective of the testing was to determine optimum conditions for effective stimulation of beef carcases under production conditions on a commercial slaughter floor.

Nine tests were completed between June 1980 and February 1981 each involving measurements on up to 40 carcases out of a single day’s production.

The report summarises the effectiveness related to animal characteristics, time after stunning and stimulation conditions. It provides further findings and recommendations regarding unit configuration, duration of stimulation, voltage, pulse frequency, electrical resistance of carcases and power requirements.

Project report 0576 investigated the effect of electrical stimulation on the bleeding of cattle at slaughter.

The objectives of this project were to determine if electrical stimulation causes:

• An increase in blood loss; and
• Blood to be expressed from the muscle tissue.

This report shows that electrical stimulation of the carcase after sticking increases the weight of blood discharged from the carcase but, the additional amount of blood released by the carcase is not expressed from muscle tissue.

Project report 0379 investigated extra-low voltage stimulation of beef carcases using a rectal probe.

Two experiments, one with young steers, the other with old cows, were conducted to determine the effectiveness of stimulation with a rectal probe used in conjunction with a stimulation unit having a maximum output voltage of 45V DC.

In both experiments, hindquarter muscles from stimulated carcass were more tender than the corresponding muscles from comparable carcases that had not been stimulated.

This method of stimulation had no effect on forequarter muscles. Because the stimulation unit uses extra-low voltage (ELV) guarding of the probe or carcases is not normally required.

Project report 0179 described experimental work on beef stimulation and outlines alternative systems and methods of implementation.

Two alternative systems were fully automatic, high voltage systems, requiring isolation in a protective enclosure. In one method, the current floweds lengthwise along the carcase, from a live electrode making rubbing contact at the neck region, though the Achilles tendon roller hooks to the earthed rail. In the other method, the trailing roller was diverted onto a parallel, isolated, electrified rail and the current flows down one leg and up the other to the earthed rail. Both methods required sufficient length of line for 90 seconds stimulation.

Most existing slaughter floors wouldnot have space for such a system. The third alternative was the rectal probe method, which used existing space on the bleeding rail. No guards were required as ELV was used. This method can therefore be implemented very simply and at a very low capital cost, but had a recurring labour cost.

Project report 283 evaluated the AIS nostril-rectal extra low voltage electrical stimulation system for its effect on the tenderness of a number of beef cuts including:

• topside - semimembranosus muscle
• striploin - longissimus dorsi
• rump - gluteus medius
• silverside - biceps femoris and semitendinosus.

The report documented the findings from the evaluation.

Project 0483 investigated an automatic beef side orientation device to assist with orienting caracsses pre-stimulation.

Under project MRR481 experiments were undertaken in 1981 to determine the maximum time after stunning at which 800V RMS produces effective stimulation for beef sides.

The MRR 485 1985 project evaluated alternative methods of applying extra-low voltage stimulation, while project MRR 588 evaluated two commercial extra-low voltage stimulation systems, which met Australian regulations, in four abattoirs for their ability to prevent cold shortening.

Project MRR 393 evaluated use of an electronic monitor for use with ELV beef carcase stimulation units.

Later Research (post 2000)

From 2003 onwards, key MLA R&D staff such as Ian Richards collaborated with Australian and New Zealand researchers in the commercial development of stimulation and immobilisation technologies.

One specific project was the development of stimulation electrodes to suit single leg suspension in sheep (P.PIP.0142, P.PIP.0165). With the knowledge gained from recent developments in wool-on sheep immobilization, there was a possibility that electrodes could be developed which could work on sheep carcases suspended by one leg in the bleed area. The method to be attempted was to use multiple blade electrodes positioned on either side of the carcase which would reduce the twisting of the carcase (twisting has been the obstacle to blade electrodes in the past). This project attempted to develop a working production prototype which effectively stimulated the carcase.

Facilitated adoption

To assist of the takeup on this Generation One technology, a series of MLA Donor Company PIP projects were funded with key beef and sheep processors. By 2005, facilitated adoption and commercial sales were 22 LVES/MVES and 2 immobilisation (sheep) and 16 LVES and 14 immobilisation (beef).

Under project P.PSH.0270, MLA and the commercialiser co-funded further refinement and cost reductions in the stimulation electronics so as to lower the entry cost for processors. This has led to two versions (generations) of the electronics being used by processors (supplied by AST and HE Tech respectively).

Outcomes (beef)

The two most important reasons to install the new technologies in beef plants have been:

• Better meat colour due to more efficient bleeding with the LVES
• Effective elimination of involuntary kicking at shackling with the HFEI and hence improved OH&S outcomes.
• Beef stimulation to increase tenderness does not appear to be a major driver for installing a LVES, as the pH decline curve for beef cannot always be effectively manipulated to improve tenderness.

Outcomes (sheep)

From 2003 onwards, first Woolworth and shortly thereafter also Coles started to adopt SMEQ grading criteria and thus the requirements of electrical stimulation of sheep meat, and especially lamb. Furthermore, the sheep meat processing industry was quick to recognise the need for installing ES systems, and as a consequence the proportion of poor eating quality sheep meat has decreased from approximately 20% to almost 0% in some recently sampled plants (MLA 2005).

Adoption

Currently (mid 2014) there are 116 installations of Gen One technologies (AST and HE Tech) in beef and sheep plants. 88 of these are in Australia with the balance overseas. Furthermore, similar competing technologies have been developed by other New Zealand companies and are also being sold in Australia.

The uptake of this technology has significantly improved the eating quality of sheepmeat, although challenges remain as regards the support and maintenance of existing sites, as these need to be regularly serviced and 'tuned' to maximise eating quality.

Project V.EQT.1407 funded an audit and survey at 14 sites ranging from small to large producers of sheep and beef to gauge the compliance of equipment and establish their requirements for developing their capabilities. It was found that two sites had no issues with their equipment, 5 sites had equipment needing repair and 7 sites needed advice for better operation of their current equipment or a source of effective equipment. Discussions are underway to address this gap at an industry level.