Traditionally in South Africa, drying of biltong was achieved by hanging the strips of meat on hooks and leaving them to ambient dry. Nowadays, home made biltong may be made Page 13 of 87 using a biltong-drying unit (Naidoo and Lindsay, 2010) whilst large scale operations use commercial dryers. The colder moisture ambient conditions in the UK, compared with South Africa, are not conducive to the making of biltong in ambient conditions.
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A warm dry environment is required for making biltong and Table 4 indicates that a
n air temperature of 35ºC will enable a microbiologically stable product to be produced in a around 6 days (144 hours). A lower air temperature would require a longer drying time and increase the microbiological hazard due to the slower drying rate. Whilst a heater can be used to raise the air temperature for drying, relative humidity of the air (related to pa in the equation above) also needs to be considered. For example, in the UK, typical weather conditions in the Summer would be 18ºC and 65% relative humidity.
Heating this air to 35ºC would produce a relative humidity of 24% which is below the 30 to 40% found in Table 3. The product would dry sufficiently in less than 6 days. The drier must be ventilated to allow fresh air to enter and some moist air to leave. Adjusting the rates of air intake and exhaust would allow the relative humidity to be controlled. For Winter weather in the UK, the temperature and relative humidity might be 4ºC and 85% relative humidity and heating this air to 35ºC would create a relative humidity of 12%. The product may become over-dried if all of the air is allowed to pass into the oven and immediately out again. Restricting the flow of air out of the drier and, perhaps, slightly reducing the air temperature may be required depending on the product moistness required and the need to prevent case-hardening. Allowing some of the air to recirculate in the oven would enable the relative humidity to increase. The speed of the air in the equipment used for drying also affects the rate of drying through the mass transfer coefficient (discussed above) because it moves hot air towards the meat and Page 14 of 87 removes moisture from the meat surface and also from the drying equipment. Few data have been reported on the air speeds used in making biltong. Traditional ambient drying relied on the wind.
Some driers produced for home use rely on the convective effect resulting from the heat source in the drier: in some cases, this is nothing more than an electric light bulb. Data reported in Table 4
suggest an air speed around 2.5 to 3 m/s. Lower speeds would reduce the drying rate but higher speeds would lead to little increase in drying rate because the rate of drying would be restricted by the rate at which moisture can move within the meat to the surface. Figures 1 and 2 show the change in moisture content, water activity, salt content and bacterial numbers during the drying of biltong in air at 35ºC, 30% relative humidity and 3 m/s. A suitably dry product is achieved after 144 hours but the microbial load would likely decrease further with longer drying. Conversely, reducing the drying time to 72 hours (3 days) would create a product with a moisture content between 30 and 40% but the microbial load would be higher. pH may also have an influence on the safety and shelf life of meat products. Fresh beef has a pH around 5.8, generally in the range 5.4 to 6.0. Table 4 shows that biltong from fresh meat retains it pH at around 5.6 to 5.9 unless some severe acidic treatment has been used in the preparation
From:
acm982rep.pdf (food.gov.uk)
Hope this helps :) Bolding is mine.
I use a
ProQ Food Smoking Cabinet, with a PC fan and a heating element in the bottom controlled by an Inkbird Temprature controller. I just have it free standing in my garage with suitable ventilation.
I think you're going to have issues with airflow, temperature and humidity doing it in a fermentation fridge.
