Gday,
I am lucky enough to work in an area that has plenty of Purple Mangosteen fruit available. Supporting the local people in their small market I have in the past ordered 20kg of mangosteen and eaten them all in a matter of a week or so. I was collecting the seeds to take back to Oz to plant in our garden. This I have done with no issues from customs at the airport as long as they are declared and clean I haven't had any problems. The only issue is that they are normally sprouted quite long by the time I get home and I think this might weaken the seedling but I am not 100% sure about this. Anyhow back to the story, last trip in to work I purchased 6kgs of fruit in Vientiane and ate them upon arrival to site 5 hrs later. I put the seeds in some 2nd hand vermiculite that I had in the cupboard from where I had brought some Z4 abiu seed over for the lads here at work who are mostly slash and burn type rice farmers. I put the seeds back into the cupboard and completely forgot about them. I worked for my roster of 4 weeks and then went on break for 2 weeks back to Oz. When I got back to site next time I found the seeds in the cupboard and they were still alive. See attached pics. The shoots were very long but they were still very much alive. Tough these little buggers!
I have found that I don't have any issues with mould because we clean the seeds properly as we are eating the fruit. Because we have had so many fruit I have been very rough with the seeds and found that sort of chewing the skin off the seed once the fruit has been eaten off it works the best and you can get quite rough. Sometimes the seed will crack in half but if the complete skin is not removed we have trouble with mould. Take all the brown skin off if possible and just leave the creamy colour seed, put it in a clip lock bag with just a touch of moisture in there and away you go. With this method we have been getting around 90% and more germination of the seeds with no mould issues.