In the first issue of the RFC newsletter, I wrote an article on fruit drying in which I mentioned my search for machines suitable for drying in the very high levels of humidity which we experience in Far North Queensland.
I have read many books, bought numerous plans and inspected a variety of machines in the past two and a half years, until at long last I have found a machine which has most of the desired good features and none of the undesirable bad features.
The essential requirement in drying is to remove moisture with the least damage to the fruit or vegetable being dried. Heat is obviously essential, but very strict temperature control is required to prevent cooking or case hardening at one end, or moulding at the other.
The second essential is to ensure that the moisture removed from the fruit is well-dispersed into the atmosphere and not merely left in suspension in the hot air surrounding the fruit.
Thirdly, the air flow should be as even as possible to allow consistent levels of drying on all shelves without having to rotate shelves every couple of hours. Air flow, desirably, should be such as to allow drying of different fruit on different shelves without spreading flavours (ending up with a fruit salad taste no matter what the particular fruit).
Other design features call for ease of cleaning, both the individual shelves and the unit; use of inert materials which do not absorb either juices or flavours; compactibility, etc.
Add to all these the basic essentials of efficiency, cost of operation and initial cost.
Most dryers are square in shape with the electric element at the bottom - those with fans distribute heat upwards and over individual shelves to exhaust at the top of the machine. The first noticeable thing about Excalibur is that it is only 8½ inches high and has a horizontal air flow. The thermostatically-controlled element is sited at the rear of the drying trays and a fan produces a current of air over the product being dried, heating it and carrying the surplus moisture forward to exhaust at the front. The thermostat controls a 600 watt element to give a constant temperature range from 95° to 145° C.
Five trays slide into individual slots, giving a total drying area of almost 8 sq. feet, enough for 25 lbs of fruit or vegetables.
Construction throughout is of inert dishwasher-proof plastic, providing an excellent surface which is extremely easy and simple to clean.
The door is of see-through plastic, enabling a check on drying without the need to open the machine.
From first appearance, Excalibur met with my stringent requirements.
The next question was the obvious one - was it as efficient as its appearance led one to believe. Accompanying the dehydrator is a booklet giving instructions for drying a variety of fruit and vegetables, together with details on other uses such as yoghurt making, bread-rising, herb, flower, fish and meat drying and topped off with a collection of recipes for using dried ingredients.
Working by the book, we set out to test it. Mangoes not being available in May we settled for a case of Granny Smith apples. Drying time with rings 3/8" in diameter was less than the recommended 10 hours. The product - excellent, with almost no deterioration either in flavour or colour.
The next test was on pears - and this time we treated half with lemon juice. The result in 20 hours was too good - we had brought the moisture content too low and had crisp rather than pliable fruit. Left in the open for a couple of hours to naturally rehydrate, they were fine. Next time we'll cut them thicker or reduce time (or both). The difference between the natural and the lemon-treated fruit was barely distinguishable, indicating excellent drying with a minimum of oxidation.
Trials were then made with bananas, both Cavendish and sugar varieties. The latter were a little under-ripe for optimum drying but the result in both cases was surprising. I had never before seen a dried banana which was not brown - almost dark brown. Excalibur-dried bananas were golden. (We cut them lengthwise into three or four, dependent on thickness). Flavour very good.
We then turned to vegetables and very successfully began to fill jars of tomatoes, onions, beans, carrots, chillies, coconut and zucchini, to mention but a few. In all cases, we were fully satisfied with the results.
Our next venture will be fruit leathers - with the amount of over-ripe fruit around, fruit leathers will be one of the major items we need to produce.
Now what about running costs. In Brisbane it has been costed at 3 cents an hour - with FNQ electricity costs (not forgetting the increase this month) a figure of 5 cents an hour seems reasonable.
The machine measures 17" x 19" x 8 ½" and weighs 8 kilos - a very neat, compact unit.
DATE: September 1982
* * * * * * * * * * * * *