Dehydrating fruit - part 3

So the Hendi 6 tray unit arrived. Ordered from sousvidetools.com on Sunday afternoon, it arrived at 9am on Tuesday. A quick test confirmed that the fan went round and the heater worked, so far so good.

The instruction book  is as useful as a chocolate fireguard:

The unit is reasonably robust, the casing's polypropylene and the trays are stainless. It's fine for domestic use but would probably last about a morning in a professional environment. Also the cable length at 1180mm is a bit mean.

1. I don't understand this limit. The unit's probably at a steady state in 30 minutes or so so what's wrong with running continously for 24 or 48 hours? A week might be a bit long but 20 hours? I suspect it's some arse covering to discourage long term, unattended operation but I might be wrong.
2. Now that I'm an expert, I don't agree with this either. At the end of the dehydrating process, turn the heat off and keep the fan on for 30 minutes or so. The food can't be packed until it's cool so you may as well use the fan to speed things up.

The first load.

We have lots of wild plums, generally 19 - 25mm diameter, foraged locally.
They're a bit sharp and need a fair bit of sugar in a pie, impossible to eat raw without wincing.
They were washed, halved and stoned.
In the interests of science, I decided to weigh one of the trays at more or less equal intervals and plot the weight loss over time.
In retrospect I should have weighed them all; weight loss for each tray would be an indication of how well the airflow is distributed across the trays, maybe another time.
The first tray went in the upper centre slot and had a two hour headstart, fan only, whilst I prepared the rest. As well as the plums I tried apple, pineapple and banana.
The apples were cored, peeled, sliced about 5mm thick then dipped into a weak water/ lemon juice solution to minimise browning.
The pineapple was prepared with one of those screwy slicery things that cuts a helix of fruit and removes the core, then quartered and cut through the thickness if that makes sense.

Anyway, the target weight loss was 80-90%.
The temperature was set at 65°C, the temperature of the air leaving the vent varied 50 - 55°C.

Results

Star of the show was the pineapple which was exquisite.
The plums had a bit of variation to the dryness and are now in a sealed bag to balance out the moisture but they are sweet and there's no more wincing.
The banana looks disgusting but is very nice and the apples are fine as well so a pretty good first run.

A few notes

A screwy slicery thing

Tray detail

The holes in the stainless trays are 13.5 x 13.5mm and some of the plums fell through to the trays below after shrinking. The surface is bumpy which I suppose is to reduce sticking. The pineapple stuck a bit but was easy enough to remove by turning the tray upside down and poking from below.

There is also a plastic mesh supplied, the larger holes are 3 x 2mm, maybe I should've used it...

Headstart

The plums probably would've been more consistent if they'd all had the 2hrs fan to start with.

The use of the fan only is a pretty good idea, it achieves a reasonable rate of moisture loss without paying for the heat, remember where you read it first.

Inspired by Коля. Спасибо m8!

Watch this space.