Papaya seeds contain papaine, an enzyme that has many applications one of them being to help digestion. It also help to avoid or to get rid of intestinal parasites that don’t like the pepper like taste of these seeds. A few seeds are enough and you can eat them together with the papaya. The hot taste of the seeds mixing together with the sweetness of the fruit can be quite nice. People who enjoy eating spicy will like these seeds and may even want to dry them and use them as black pepper. As for me, I rather choose the most mature seeds, that have a milder taste. We can recognize them because they are the most black, having lost almost all their transparent gelly skin and they may have sometimes a bumpy structure or a different shape. I like their taste, recalling, from far, the taste of cheese or bread (from very far), whereas the younger seeds are too spicy for me. If you have a lot of mature seeds in your papaya, then you know that it’s likely that it was ripe from the tree.
It is important to mention that papaine may lower the blood pressure, people with low blood pressure should be careful about green papaya and papaya seeds, some people believe that salt hinders this effects, so eating papaya salad (usually salted with fish sauce) should be fine.
Papaya has a lot more of medical applications, from the leaves, the latex, all parts. We can for instance clean a wound with the green papaya sap, by making a small cut on a green fruit still hanging on the tree and collecting the sap dripping from it. Thaï people use the green papaya as a vegetable for their famous « som tam », papaya salad. They finely slice the fruit with a knife or a tool made for it, and add to it lemon or lime, garlic and fish sauce as main ingredients. Then they would add chili, tomatoes, roasted peanuts, long bean (eaten raw to balance with the spicyness of the chili), white shredded cabbage, carrot, and dried shrimp. Adding to that : sugar and tamarind. If you grow papaya out of the tropics and have them green but never ripe enough, this may be a nice way to eat them ! You can pick whatever ingredient you like from the list or adding new local ones and make your own combination.
As for the fruit when it is mature, it has plenty of vitamins A, B and C, a few slices cover our daily needs for vitamin C. Of course, if your region doesn’t grow papaya, local fruits will provide you with the best nutrients, as fruits lose their vitamins every hour they wait from being picked from the tree to being eaten, this period of time is longer with imported fruits. Nothing is better than a fresh and local fruit.
How to chose the ripest papaya ? Pick the ones that have a fruity papaya smell or that are not too hard when pressing it. You can feel the density of the fruit by pressing gently, and feeling if it’s deep hard or a bit soft inside. The yellow papaya type should have an orange colour, and the more village style green papaya, that hide inside a strong orange orange sweet flesh, can have only some orange marks on the skin and be very ripe : pressing and smelling are maybe the best indicators for fruits maturity. I feel that the best smell will come from fruits that could get ripe before they where picked from the tree.
Papaya can be integrated as a daily food because it’s a fruit that grows easily and all year long. The taste is sweet and it contains a lot of water, and, adding to that, one of the only fruits that doesn’t have an acidic pH, which is supposed to bet better for teeth.
Some people are more attracted by sour fruits, or less ripe ones, even still green, whereas other people are crazy about sweet or very ripe fruits. I am still wondering why, I beleive this could depend on their body type, such as ayurvedic types, or on their stomac balance (if they have a lot of acidity or not), it could also be related to their diet (vegan or raw diet can make the people crazy about sugar, but they may chose these diets because they already love sugar), and acidity is considered to help digesting meat, especially the acid from pinapples, that has singular properties.
Source : Natural medicine in the tropics, Anamed.ned (Association for a natural medicine)