Having the responsibility of purchasing the second largest amount of pepperoncini for a restaurant chain (Papa John's is the biggest), they are never processed in a jar or can for commercial use. They are only brined.
Greece grows the most of them. Spain is #2. They harvest them all at once, in the early summer, then vat them up in a very very very unedible brine. Its important to note that these peppers are 'needled" - that is they are all punctured all over so that the brine enters the cavity of the pepper.
They sit for about a year. Then next year, the processors all over the world book their needs with the Greeks. These containers come over by boat, dock into NY and then get trucked to the pepper processors. Once they arrive, the peppers are washed, then washed again. This is to get rid of the horrible salty brine.
My specs for the chain I worked for, was a triple wash. Then they are packed into fresh brine again, in vats, but a fraction of the size of the Greek containers. Upon order, the peppers are repacked into jars, pails, plastic bags, etc and distributed to the distributors who sell them to the restaurants. The specs were water, salt, vinegar and a preservative to retain color. We also allowed tumeric to retain/enhance the color.
Due to the salt and vinegar percentages, they were shelf stable. You can check the internet for exact proportions.
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