Views: 11 Author: Site Editor Publish Time: 2021-11-01 Origin: Site
Drying meat at natural temperatures, humidity, and air movement, including direct sun rays, is the oldest method of meat preservation. It entails gradually dehydrating pieces of meat cut to a specified uniform shape, allowing for the equal and simultaneous drying of entire batches of meat.
Warm, dry air with a low humidity of about 30% and generally minimal temperature variations between day and night are ideal conditions for drying meat. However, with the correct meat drying equipment, meat drying can be done successfully in less-than-ideal conditions. The drying process's intensity and duration are determined by air temperature, humidity, and air circulation. High temperatures, low humidity, and vigorous air circulation will speed up drying.
The evaporation of water from the meat's peripheral zone to the surrounding air and the constant migration of water from the deeper flesh layers to the peripheral zone reduce the moisture content of the meat.
During the first day of drying, there is a relatively substantial evaporation of water from the meat, which then gradually diminishes. Weight losses of up to 60–70% can be recorded after drying the meat for three or four days, comparable to the amount of water evaporated. As a result, moisture losses can be tracked by adjusting the weight of a batch during drying.
The shrinkage of the muscle and connective tissue caused by continuous evaporation and weight losses during drying causes changes in the form of the meat. The meat portions get smaller, thinner, and wrinkled to some extent. The consistency changes as well, from soft to firm to hard.
In addition to these physical changes, there are certain metabolic reactions that have a significant impact on the organoleptic properties of the product. Meat used for drying in underdeveloped nations is typically derived from unchilled carcasses, and rapid ripening occurs during the first stage of drying since the meat temperature remains relatively high. As a result, the distinct flavour of dried meat differs significantly from that of fresh meat. The characteristic flavour of dried meat is enhanced by a slight oxidation of the animal lipids.
When raw meat contains a significant percentage of fatty tissue, undesirable changes in dried meat may occur. The relatively high temperatures used during meat drying and storage induce extensive oxidation (rancidity) of the fat and an unpleasant rancid flavour, which has a significant impact on the product's palatability.
Meat drying is a complex process with several significant processes, beginning with animal killing, carcass trimming, raw material selection, proper cutting and pre-treatment of the parts to be dried, and the organisation of drying facilities. Furthermore, the impact of unfavourable weather conditions must be considered in order to avoid quality issues or production losses. The key to proper meat drying is to establish a balance between water evaporation on the meat surface and water migration from deeper layers.
Uneven air distribution is a typical and important technological difficulty in meat drying equipment. An investigation employing CFD (Computer Fluid Dynamics) simulation and measurements in a heat pump chamber dryer demonstrated erratic airflows. The airflows could be seen and optimised after simulations with modified parameters and other chamber adjustments. It was demonstrated that modifying the chamber with a revolving disc had a good influence on the uniform distribution of air flows in the drying chamber.
The change improves the energy balance of the beef drying process dramatically. The technique was optimised, resulting in a high-quality final product-beef jerky. Appropriate drying process management and implemented adjustments allow for great product quality and a safe level of water activity without the use of preservatives.