I have to 'share a scare' that happened with my recipe. I use a traditional family recipe, nothing fancy. I started supplying a farmer's market and it is very popular with return customers. I put it into jars, tapped out the air bubbles, put a few drops more olio on top and sold away. I recommended customers to use it straight away, but they could freeze it (out of the glass jar) or once opened, cover in oil and put on a shelf out of the sunlight. That is how Nonna used to do it anyway.

One of my friends that is trying to get my recipe into shops, etc bought a jar and left it for 10-12 days before opening. It had gone off - more accuratley, the cheese which had to be fresh had gone off. It would certainly caused food poisen if eaten. What went wrong?

I have since been advised and will report on the results of: 1-using ALOT more olio, 2-sealing the headspace of the jar with parafin wax (designed for food)so NO air is in the jar 3-excluding the cheese and selling it seperatly advising to add cheese when consuming.

I am also putting on the label to consume within 2-3 days once the seal is broken.

I have looked at ALL the jars on the shop shelves and they have acidifiers, but they are also vacuum packed. (p.s. they also don't even come close to Nonna's recipe for taste!)

I will post any advice I get and I ask other pesto lovers to work and share info as well. The dish is one of the cullinary gems and needs to be shared!