as long as when you harvested it, it showed some color at the blossom end (called the breaker stage). At this point seeds are mature and the ripening process is triggered (to help disseminate those seeds).

Breaker stage is second from left:

Bumping this so it will stay around a bit longer.

And here's a new fruit development chart:
http://www.lagorio.com/assets/pdf/lagorio-tomato-guide.pdf
[Firefox pointed out that this did not open in a clean format, and offered to open it in Adobe instead: luckily, that version came up without errors.]

can you tell me please how best to save the seeds, do i need to wash them?? and how to dry them quickly, so as to not let them rot???

The Seed Saver forum will be the best place to answer this type of question. The FAQs Q and short Answers are listed at the top of the forum.

Even this tomato forum might have some FAQs on the subject.

There are two methods:

1- just wash and let it dry.

2- FERMENT. In the method you smash the whole tomato in a small bow. Cover it . Keep is in a warm place in your kitchen ( few days) until you see white mold on the top. Then wash it, rinse it. Separate the seeds and dry them out as usual.

Fermenting method is said to disinfect in case of viral contamination. I am doing this way right t now. But I have done it the conventional method over the years and never had any problems with germination.

Initially is was said that fermentation removed the gel capsules on the seeds, and it does, and also with the help of enzymes from the fungi in the fungal mat that you let form frees the seed from tomato tissue,, and it does, and it was also said that it inactivated any seed borne viruses, and that is wrong since all viruses to date have been found to be in the endosperm of the seed and fermentation can only address pathogens on the seed coat.

And it does, in terms of eliminating most of the tomato foliage pathogens as well as some systemic ones. And this we know from the work of Dr. Helene Dillard which I've posted here several times.

I will only use fermentation to process seeds, not any of the oxidative methods b'c there's no data to confirm what the oxidative methods can do although many have searched for such data.

There are a couple of good places to go to about how to do fermentation correctly. One is at Tania's T-base site and another is at Victory Seeds,

Carolyn

Advantage of fermentation Method:

In the conventional method you cannot separate the good , viable seeds from the worthless one. Because of the gel around it.

But when fermented, the seeds are freed from the gel. So when you process the product of fermentation in a tall cup/glass( by adding water and stirring) the viable seeds would sink to the bottom. So by pouring about half of the water, the particles and the bad seeds are discarded. You keep doing this several times and end up with a bunch of heavy viable seeds at the bottom of the cup.

The advantage is that there is a leas chance that any of those seeds will no germinate.