Rosalee Brown

It is an accepted practice to 'condition' or 'ripen' beef after slaughter to develop its characteristic flavour and improve tenderness, especially in cuts closer to the ribs.

In the ageing process, enzymatic reactions take place which act on muscle proteins, breaking them down, thus increasing tenderness. This increase in tenderness is greatest at three to seven days post-mortem, after which the rate decreases.

Many older Jamaicans will remember, if they have ever been to a beef shop, carcasses being aged naturally by hanging them from the ceiling overnight and even for more than one day, to allow for ripening. I am not sure how pervasive this practice is now, as this is prohibited by public health standards.

Dry ageing

There are several methods which can be used for ageing beef. The dry ageing method is where the entire carcass is placed in a room uncovered at a controlled temperature of 32 to 34 degree Fahrenheit and at 80 to 85 per cent relative humidity and wind velocity of 0.5 to 2.5 minutes per second. Humidity is important, as too much can increase the moisture in the air which speeds microbial growth and the wind is important in the removal of moisture.

Wet ageing

Wet ageing is another method where the meats are placed in vacuum bags under refrigerated conditions of 32 to 34 degrees Fahrenheit. Humidity and air velocity is not a consideration in this case since the meat is vacuum packed.

Both methods are said to develop the characteristic flavours, but there are characteristic differences in the end products. The vacuum packed method is said to have a more bloody metallic flavour, while the dry method has a more beefy flavour.

In Jamaica, most small butchers usually sell their slaughter in a day and leftovers are refrigerated. The few large farms with greater amounts of slaughter are required to adhere to the standard of ageing at the controlled temperature. It should be emphasised that control of temperature is vital in this necessary ageing process.

The conditions of slaughtering are also important. Contamination from dirty hands, surfaces, clothing etc., can increase the total variable count of bacteria on the surface of the carcass, thus increasing its spoilage time or reducing its shelf-life. Keeping the meat cold or at the correct temperature is the next important thing in reducing spoilage or increasing the shelf-life of the beef. Microorganisms rapidly multiply at increased temperature.

The bacteria relevant to meat spoilage can be divided into three groups according to the temperature range at which they can grow.

The mesophiles, such as salmonella type bacteria, which need a moderate temperature of 15-45 degrees Celsius to grow. These bacteria are most responsible for food spoilage.

The psychrophiles are capable of growth at 0 to 28 degrees Celsius.

Psychrotrophs, which are capable of growth below 5 degrees Celsius.

So, bacteria can survive at varying temperature ranges. Some of these bacteria will cause food spoilage, limiting shelf-life of the meat, but others will cause food poisoning, resulting in illness.

As consumers, we need to be aware of the impact of temperature on some of our favourite foods and we must be vigilant in demanding that these standards are kept.

Rosalee M. Brown is a registered dietitian/nutritionist who operates Integrated Nutrition and Health Services; email: yourhealth@gleanerjm.com.