Cansplaining: Cooking with tinned food is healthy

Food writer and anti-poverty campaigner Jack Monroe is the go-to for making easy, nutritious meals with store cupboard essentials, and debunks the myth that tinned food isn't good for you

Monroe is an expert at cooking on a budget (Patricia Niven)

I knew as soon as I pitched the idea for the Tin Can Cook that I would be deluged by critics keen to share their perceived wisdom about how “canned food isn’t good for you”.

I’ve had this throughout my career as a food writer – from comments on my Guardian recipes, to emails, to a handwritten letter on fancy notepaper informing me that I was a “dangerous woman” for using tinned potatoes.

Here is my retort to the cansplainers, once and for all; an A to Z of tinned goods, and how great they really are. I’ve tried not to go too heavy on the science, and I hope it makes for interesting reading.

A detailed study by the University of California found that “freezing and canning processes may preserve nutrient value”.

However, the initial thermal treatment of processed products can cause loss of nutrients such as vitamin C and B vitamins, researchers found.

But these nutrients are relatively stable during subsequent canned storage owing to the lack of oxygen. Frozen products lose fewer nutrients initially because of the short heating time in blanching. The scientists, who published their study in 2007 in the Journal of the Science of Food and Agriculture, conclude: “Exclusive recommendations of fresh produce ignore the nutrient benefits of canned and frozen products.”

On top of that, many fresh fruits and vegetables have a shelf life of only days before they are unsafe or undesirable for consumption.

The study authors add: “Storage and processing technologies have been utilised for centuries to transform these perishable fruits and vegetables into safe, delicious and stable products. Refrigeration slows down the respiration of fruits and vegetables and allows for longer shelf lives.

“Freezing, canning and drying all serve to transform perishable fruits and vegetables into products that can be consumed year round and transported safely to consumers all over the world, not only those located near the growing region.”

In short, although canning can cause a slight loss of some nutrients, notably vitamin C in some fruits and vegetables when heat-treated, the nutrient value once canned remains stable. And nutrients from canned and frozen fruits and vegetables are more desirable than none at all.

There is some consternation about the potential presence of bisphenol A (BPA) – a plastic coating chemical – used in the lining of some tins. BPA can theoretically interact with oestrogen receptors in the body. The US Food and Drug Administration states that “normal levels of canned food consumption have no adverse effects on general health”, and as of 2016, major manufacturers have pledged to remove the BPA lining from their tins. I mention it merely as a precaution – and because it would be remiss of me to overlook it – but not to cause alarm.

Cansplaining at a glance

Baked beans
Look out for the low-salt and low-sugar versions of these. Baked beans are a source of magnesium, phosphorous, potassium, zinc and copper. In some of my recipes I rinse off the sticky orange sauce and use them as small white beans, in others I’m happy to just sling the whole lot in, sauce and all.

Lentils
Due to their fibre content, lentils can help to lower cholesterol, which is part of the maintenance of cardiovascular health. The slow release of complex carbohydrates helps to stabilise blood glucose (sugar) levels. They are a good source of fibre, B vitamins including vitamin B9, protein, copper, iron and manganese.

Coconut milk
Containing a mixture of saturated and non-saturated fats, coconut milk is a good source of potassium. Use it in curries, as a base for soups, or for baking in luxurious breads.

Lemons (preserved)
These are high in vitamin C, which isn’t adversely affected by the process of preserving them. Unusually for a lemon you can eat the whole thing – skin and all – providing some extra fibre rather than just squeezing out the juice.

Carrots
Known for being a source of beta-carotene that is converted by the body to vitamin A, carrots are also a good source of vitamin K.

Chickpeas
Also known as garbanzo beans, chickpeas are a good source of protein, carbohydrates and fibre. The iron, phosphorous, calcium, magnesium, manganese, zinc and vitamin K in chickpeas all contribute to building and maintaining bone strength.

Beef (stewed steak)
Beef is a good source of protein – even beef that comes in a can! You can also grab yourself some vitamin B12, zinc, selenium, iron, vitamin B3 and vitamin B6 here.

Extracted from Tin Can Cook: 75 Simple Store-cupboard Recipes by Jack Monroe. Published by Bluebird, £6.99