/ Food & Drink

Not the best-o pesto: how do you make yours?

Our investigation found that pesto sold by some supermarkets contains a number of surprising ingredients. Do you add anything extra to your pesto to make it the… best-o?

Generally accepted as a Genoese invention, traditional pesto contains just basil, pine nuts, Parmesan and olive oil (as well as a pinch of salt and squeeze of lemon). However, our investigations team found supermarkets such as Tesco, Morrisons and Sainsbury’s have been adding extra ingredients.

Bamboo fibres, glucose syrup and cashew nuts were found in some of the pestos. And in others, pine nuts had been replaced with cashew nuts, olive oil with sunflower oil and Parmesan with cheaper Italian hard cheeses

Morrisons, Sainsbury’s and Tesco’s premium ‘alla Genovese’ pestos all contained vegetable or bamboo fibres as thickeners, as well as added sugar. And Morrisons Pesto alla Genovese also listed water as an ingredient. M&S’s standard pesto contained carrot fibres.

Asda and Waitrose did better – their products had the most authentic and traditional ingredients. You can read more about our pesto research results here.

Hey pesto!

Is pesto the real thing if it contains ingredients other than basil, pine nuts, olive oil and Parmesan? Some recipes substitute almonds for pine nuts – Hugh Fearnley-Whittingstall even goes so far as to say you can replace the nuts with breadcrumbs. And call me a pesto heathen (or maybe visionary), but I too play around with the traditional ingredients.

I made a wild garlic pesto this weekend which had no basil in it at all. The wild garlic – out in force in woodlands at the moment – gives it an amazing spiciness that’s still well balanced by the cheese and nuts. I also substituted half the pine nuts for walnuts because I like the bitterness (but I did stick to traditional olive oil and Parmesan – no shortcuts here).

I’m not sure what the Genovese would make of it, but wild garlic pesto has become a firm favourite among my friends.

But coming back to shop-made pesto, Nikki Stopford, director of research at Which?, advises to “check the ingredients list if authenticity is important to you, or if you are trying to avoid certain contents, such as added sugar… our advice is not to assume that all pesto contains the same traditional ingredients.”

Is my recipe as great a culinary crime as supermarkets adding bamboo shoots and vegetable oil into the mix? And do you have a similar non-conformist pesto recipe? Let us know your best-o ideas.


I’ve never made pesto before – maybe I should! My favourite things to have with pesto is nachos, tomatoes and mozzarella.

I buy my pesto from Tesco (for convenience) and I’m not to fussed that they add extra ingredients, I still like it. I think it should be clear what is in the pesto – avid pesto fans would be upset if it wasn’t made the way it should be.

Does pesto really contain as much basil as declared or is the description fawlty?

I wonder if the surprise ingredients were obvious from reading the ingredients list or have the manufacturers been adding undeclared ingredients, which would be fraud.

It’s well known that high price foodstuffs such as saffron are frequently adulterated but I remember we discussed the adulteration of oregano a few years ago: https://conversation.which.co.uk/food-drink/food-fraud-fake-oregano/

I love pesto, I’m always pining for it.


I hope no-one will say you are nuts. 🙂

“Does pesto really contain as much basil as declared or is the description fawlty? ”

Very clever Wave : )

The Which? survey covers supermarket brands of pesto but it’s not just these brands that contain unexpected ingredients. Delving into my cupboards I found a jar of pesto (not a supermarket brand but I cannot remember which brand) that contains both sugar and some cheese other than Parmesan. It’s one of these food items I keep in case a visitor wants them.

In other Conversations I have mentioned that few of us would think of putting sugar in soup, yet this is a common ingredient. There are plenty of recipes for soup without added sugar and none of the recipes I’ve seen for pesto call for sugar and glucose, bamboo and carrot fibres or cheaper cheeses. As pointed out in the introduction, even more expensive products can contain cheap additives.

Do you think this news will encourage you to look closely at ingredients in future?

Lots of pre-made sauces have added sugar – especially bolognese. I always buy my bolognese as a jar, combination of laziness and I just genuinely prefer it, but the sugar content is a concern.

Maybe I’m a bit sad but I do study the ingredients of foods. It might be a cursory glance in the supermarket but more thoroughly later, and that helps me decide whether to avoid a product in future.

Cooking sauces often contain modified maize starch as a thickener, whereas the home cook might use flour or cornflour for the same purpose. What I would like to know is how the maize starch is modified. There are various possibilities.

Sugar will obviously be of interest to diabetics but including it in foods is conditioning us to see sweeter foods as normal.

I’ve got a jar of Co-op pesto in the cupboard, bought a while ago when it came top in a newspaper taste test. Seems to be mostly cashew nuts and sunflower oil. No parmesan, very little pine nuts.
I’ve tried making my own in the past using the 4 ‘proper’ ingredients and it’s always tasted pretty vile, so I tend to stick to ready made ones.
As for sugar in bolognese mixes, I’ve seen this recommended quite often to counter the acidity of the tinned tomatoes. I add it sometimes when I remember, but I can’t honestly say I can tell the difference.

Oscar – Sugar only acts as a preservative at high concentration, as in the examples you have given. Many manufacturers have decreased the sugar content of jams etc. for health reasons, which means that it’s best to keep them in the fridge after opening. Smaller amounts of sugar won’t act as preservatives and since most bacteria and moulds grow well on sugars they may spoil faster.

Welcome to Which? Convo and thanks for your first topic.

According to authentic Italian recipes the cheese in pesto should be part parmesan, part pecorino sardo. But I don’t think one needs to take that too seriously.

Elizabeth David suggests parsley pesto with walnuts; I’ve often made it with either pine nuts or cashew nuts. In my experience it’s very worth while experimenting with different herbs, but they should be the fresh, green kind. Parsley, mint and fennel make a good pesto. And if you’re lucky enough to have lovage in your garden, then try that while the leaves are still very young and soft. When they get older it’s better mixed with some parsley or of course basil. I must try the wild garlic; it grows abundantly at the bottom of our garden. I’ve often wondered about coriander pesto but never quite had the nerve.

And you can perfectly well use a good mature cheddar cheese if your larder or your purse don’t run to parmesan. For goodness’ sake, it’s only a sauce! If it tastes good…

But not sugar.