Athene, cut them into smaller pieces so they'll ferment faster. Part rotten fruit is ok too.. Don't be alarmed, but fungus will grow on the fruit peels anyway.. yUp, any beg/fruit will work, but it's better to not mix them, as each has their own distinctive 'flavour' and smell.. Orange peel concoction smells the best, banana the worst. Can make you want to throw up..
The brown sugar is the one used in kuih.. BTW, it is advisable to leave the mixture to ferment for at least a month.. THe dark colour of the brown sugar should fade away into a lighter hue by then.. This concoction is used by some people to mop floors and also to wash clothes! But so far, my family only uses it as natural insecticide. You can try making enough to fill 1 or 2 1.5litre bottles furst. Good luck
