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These jars are nicely packed. It does look like some siphoning occurred. Yes, they are safe to eat, but the vacuum will be weak causing a shorter shelf life and the fruit above the liquid will start to have noticeable quality changes in the next two to three months. Texture and color will start to change soon. Nutrient loss will be a bit more accelerated above the liquid line. The best course of action will be to open and eat the fruit from these jars first. If undesirable browning and softening occurs, you could use the peaches to make fruit leather.
Siphoning can be prevented:
1) Use the recommended headspace - over-full jars can start siphoning during processing when the liquid boils up to the rim inside the jars. Under-filled jars can cause a weak vacuum.
2) Clean the jar rims well with hot water on a clean towel.
3) The jars need to be level in your canner. Position them correctly on the rack.
4) Tilting the jars when you take them out of the canner can start siphoning, too.
When heated, sometimes air bubbles caught under peach halves can expand and rise to the surface. This can increase the head space, too, but usually by only slight amounts. This can be prevented by using a "bubbler," a thin plastic strip that can be inserted along the peaches to gently guide visible bubbles to the surface. When the tip of the bubbler touches it, the surface tension is broken on a bubble and it will rise quickly to the top of the jar. A sharpened, cleaned chop stick or clean corn dog stick can also work. You can also tilt jars slightly and apply a small amount of pressure with the bubbler to nudge the air bubbles out of their hiding spaces.
If neither of the above options work well, hot packing your product can also limit a change of head space. Hot packing is heating the fruit before it is added to the jar. This can break cells open and release excess air. The fruit is softer so you can also get more fruit packed in the jars. Hot packing can also reduce the risk of floating.
If your peaches were canned within the past 24 hours, you may want to reprocess them so they will last longer than three months on the shelf. Use hot liquid, gently bubble the product, clean the rims well and use a new lid.
OSU Extension has free resources online: See https://extension.oregonstate.edu/mfp/publicationsLook for Canning Fruits in the Fruits and Vegetables link and instructions for making fruit leather in Drying Fruits and Vegetables in the Drying link. These publications can also be found at your local OSU Extension office, usually for a small printing fee.
Thank you so much for your thorough response! That is very helpful!
I'm happy to help!