Do spices really go off date?

Yesterday was my friend Kate’s 70^th birthday and I visited for a slice of cake and a cup of tea. Her main celebration is today, when she is cooking her family a Moroccan feast: beef stew for the carnivores and a chickpea and aubergine version for the vegetarians. I don’t know what went into the meat dish, but Kate confessed yesterday that the harissa she put in her vegetable stew was “a bit out of date”.

“I asked Johnny not to tell me how old it was,” she said. But, of course, I was all ears now – I really wanted to know, even if Kate didn’t.

John lent forward and whispered: “2005”.

I have to confess that my first thought was that, being the right side of the millennium, this didn’t sound too bad. My mother has spices dating back to the 1970s (“it seems a shame to throw them away and buy more when I use so little each time,” she reasons) – and one of my nephew’s favourite activities on visits is to rummage through her food cupboards and tweet about the ancient treasures he has found.

But then I did the maths – would eight year old Harissa be safe to eat?

“She wanted me to call you and get you to ask Steve,” John said. “But then we thought it must be fine – it’s only been open a year...!”

I imagine the harissa was already in the stew when Kate thought of consulting us - and John was wise to dissuade her, no doubt remembering the time Kate sought my counsel on reheating rice for a party. Her plan was to make the risotto a day in advance and then pop it in the microwave for her guests. My cautions about rice and bacillus cereus, a bacterium that can cause food poisoning (especially when rice is poorly reheated) did not go down well. Kate had, it turned out already made the risotto before calling me. 

I remembered the upset this caused, and decided to keep quiet this time. After all, I'd just seen the lovely vegetable stew in Kate's fridge - and I knew she was not going to change anything now. But, while dried spices just seem to fade in colour and flavour, I wasn’t sure what would happen to harissa – which is, unless Kate found something I don’t know about, a wet paste.

“Well, it’s a mild one!” Kate said as if that justified using it.

I fear it may be very much milder now –I've been Googling and  Wisegeek says harissa loses flavour and intensity with age – but since he says nothing about it turning toxic, I very much doubt anyone will suffer as a result.