I made a bottle of basil sauce by myself last year summer. It composed of basil leave, extra virgin olive oil, pine nuts, garlic and parmesan cheese.

It was kept in a glass bottle in the refrigerator, and I've add some lemon juice on the top of the sauce to preserve it.

It should be rotting already right?

  • That sounds a whole lot like pesto sauce - you sure there wasn't also any garlic?
    – Aaronut
    Commented May 18, 2011 at 2:35
  • Yeah, it is pesto, I forgot its name, so I called it basil sauce. I think there is garlic too. Commented May 18, 2011 at 3:41
  • 1
    Pesto is just Italian for paste or sauce. This is a basil pesto.
    – Carmi
    Commented May 18, 2011 at 6:20
  • If it's older than a week or two, throw it away. Next time, freeze your remaining sauce.
    – Sean Hart
    Commented May 18, 2011 at 18:57
  • 1
    Pesto will freeze better (or at least, it'll come back from freezing better) if you omit the cheese before freezing.
    – Joe
    Commented May 19, 2011 at 14:23

3 Answers 3


Last summer was a long time ago. The National Center for Food Preservation has this to say about herbs in oil:

Oils may be flavored with herbs if they are made up for fresh use, stored in the refrigerator and used within 2 to 3 days. There are no canning recommendations. ... Pesto is an uncooked seasoning mixture of herbs, usually including fresh basil, and some oil. It may be frozen for long term storage

Clostridium botulinum is a serious enough hazard with oiled herbs that I'd not trust a dash of lemon juice on top of the oil to protect me from getting sick after 9 months storage. You're much safer freezing the stuff as recommended. Ice cube trays produce nice pesto cubes that you can store safely in a freezer bag for at least a couple years.

  • Yes, and be especially wary if there was fresh garlic in that mix.
    – zanlok
    Commented May 19, 2011 at 16:42

I think it depends on how cold your refrigerator is. I'd try smelling it, and if it smells okay you can try tasting it. If it tastes okay then you're all set, but even if it's not rotten it might have lost its flavor in that time!


In future a good way to go is freezing it in an ice cube tray. Lay it in and drizzle some olive oil over the top to seal out air, and freeze. As soon as it sets up put the cubes into a freezer bag and put the bag into some sort of storage container and back in the freezer. Then you can just pop a cube out when you need some (or cut in half if you need less). Keeps a year easily, and two is possible.

  • This method is quite impressive....... Commented May 19, 2011 at 14:21
  • 1
    I do the same (without the cheese, see comment above), but I keep a separate set of ice cube trays for pesto / stock / etc ... most people just don't seem to like the trace of garlic flavor in their drinks.
    – Joe
    Commented May 19, 2011 at 14:24

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