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  • Writer's pictureLydia Gerratt

TOMATOES - everything you need to know to buy the very best for cooking and eating

Tomatoes are the one thing I always buy when I go food shopping – I can’t have a fridge without some tomatoes in it. I use them in so many of my recipes that I get heart palpitations if we run out.

Having said that, I used to be a bit tomato phobic……in the past I would buy tomatoes because I thought I should eat something healthy, but they would always disappoint; too sharp, bland, watery and worst of all, mushy.

But my tomato eating days literally changed overnight when I became Waitrose’s Fresh Salads Buyer and I was responsible for their multi million pound tomato business (I know, can you believe tomatoes make that much money?!). Sourcing good quality tomatoes was one of my preferred Buying roles during my nearly 20 years as a Food Buyer (16 of those with Waitrose).

My favourite part of the job was talking to and working with growers on the Isle of Wight and Sussex during the British tomato season and the phenomenal trips to Spain, Italy, Sardinia, Sicily and beautiful Jersey to work with generations of tomato growers when the British season was over.

They taught me everything you need to know about growing sweet tasting tomatoes and which variety to buy at the right time of year. But best of all, they taught me the perfect recipes to use to bring out the natural sugars, acidity and more-ishness that all the finest tomatoes possess.

Everything you need to know about tomatoes and my guide for buying the best

Tomatoes - Solamnum lycopersicum

Beautiful and luscious, this plump fleshy fruit was brought to Europe during the 1500s by the Spanish Conquistadors from Mexico. Spain and southern Italy (ruled for most of that time by the Spanish) developed a lasting love for this sweet, glutamate enhanced fruit and created a new food and farming culture to satisfy their appetite with a multitude of dishes.

A careful balance of sugar, acid and glutamate (glutamic acid) make up a flavoursome tomato. If the balance of sugar to acid is out of kilter a tomato can either taste too sharp or too sweet, like sugary water. The biggest problem with tomatoes grown in Northern European countries or those encouraged to grow during the dark winter months is a definite absence of sugar. They not only taste unpleasantly tart but also bland with a pappy texture. It is this, more than anything else, which puts people off buying and cooking with fresh tomatoes.

As the tomato is indigenous to the hot, Equator hugging countries of Mexico and South America it needs heat and strong light to ripen and develop enough sugar to balance the high acidity. Farmers in northern Europe (the UK and The Netherlands) grow tomatoes in large glass houses to maximise the shorter hours of daylight and vamp up the heat. Southern Europe uses glass houses to grow tomatoes during the unforgiving winter months.

Different varieties have different levels of sugar. The small tomatoes; cherry, baby plum and midi plum have higher levels of sugar than larger everyday round, plum, beef and marmande tomatoes. The sugar measurement in tomatoes (or any fruit) is called brix. A high brix means more sugar. Cherry tomato brix can be as great as 10 during the summer months while a round tomato might only achieve a brix of 5 at its peak.

Tomatoes are full of glutamate. This compound is the savoury taste known as umami. The seeds and the jelly contain three times the amount of glutamate as the flesh so it’s worth keeping the seeds and jelly when cooking with fresh tomatoes to develop a rich, deep flavour.

A tomato plant that has been stressed during its growing season by dramatic changes in temperature from day to night and/or high levels of natural salt and minerals in the water will harvest a more flavoursome tomato. Tomatoes grown on islands are highly prized as there is a big difference between day and night time temperatures and the water has higher levels of salt from the sea; Sicily, Sardinia, even Jersey and the Isle of Wight are known for their sublime tomatoes.

The rich, mineral laden Vesuvian soil of Naples grows the absolute best tomato for both cooking and eating raw: Piennolo, a pear shaped midi plum tomato. The harvests are so small that barely any is exported. Piennolo is the perfect tasting tomato to use in classic Neopolitan dishes. Locals hang their harvested vines in great bunches outside their homes so they have a supply of fresh tomatoes up until December. The Piennolo has a thicker skin than most commercial varieties with very low acidity so the flesh stays fresh and doesn’t dissolve to a mush.

The Canary Islands grow some truly delicious tomatoes. They have it all; island temperatures, high salt water from the sea, mineral rich volcanic soil, heat and plenty of light.

It’s useful to know that commercial varieties sold in supermarkets have been developed for a long shelf life to with stand the protracted road journeys from the south of Spain and Italy to supermarkets in Northern Europe. Breeding for longevity takes precedence over flavour, you just can’t have both. By carefully choosing the right variety grown in a country with warmth and lots of light for your cooking you should get a good tasting tomato. It will never compare to the taste of the rich flavoursome tomatoes grown in the south of Europe during a hot summer and allowed to fully ripen on the vine before picking and cooking immediately. But by carefully choosing which one to use for each recipe will go a long way to creating a more-ish tomato dish.

The best time of year to buy and eat fresh tomatoes is during the summer months. Tomatoes from Spain and the south of Italy taste good in spring and early summer as the temperatures are high and they are particularly delicious in early autumn when the plants, bathed in summer warmed soil, are coming to the end of their season. UK tomatoes are particularly good from mid summer when daylight is at its longest.

When buying fresh tomatoes from a supermarket, greengrocer or farmers market, always look at the country of origin and ask yourself if it was warm, hot and sunny a week ago when the tomatoes were harvested? I only buy the larger tomatoes during the summer and opt for baby plum and sometimes cherry all year round.

My favourite variety of fresh tomato for both cooking and eating raw is the baby plum tomato, particularly the Santini variety (I can only find it in M&S). The ratio of flesh to seeds and water is much greater which means the tomatoes cook down to a thick sauce with very few seeds. The skins are thin so I don’t even bother sieving them out. Their acidity is lower than cherry tomatoes with a higher brix of sugar and as you don’t need to remove the seeds and jelly, all the umami-ness is retained during cooking. I always add a teaspoon of sugar when I’m cooking with these bright red jewels during the winter as even baby plums don’t develop enough sugar at this time of year.

Tomatoes on the vine look pretty, but they don’t necessary taste any better than those off the vine. Leaving them attached to the vine helps to stop some water evaporation, but the main reason for leaving the vine intact is the luscious tomato scent given off the green stalk.

The Italians use lots of different varieties and types of tomatoes for their cooking. Plum tomatoes are good for pasta sauces as they have a lot of flesh to create a thick sauce with very few seeds and water. Cherry, midi and baby plum tomatoes tend to be used for fresh pasta sauces.

Canned tomatoes

Plump, gorgeously red large plum tomatoes are harvested at the peak of their ripeness for canning. Canned tomatoes are perfect for long slow cooked dishes like Ragu Bolognese as it doesn’t matter if the flesh breaks down so long as all the flavours meld together. The San Marzano plum grown in the Vesuvian soil of Campania is the best variety for canning. It is a long thin plum tomato, with few seeds, thick flesh and low acidity.

The canning process heats the cans up to 120oC for 20 minutes to create a long shelf life. Citric acid is added to lower the pH, make the tomatoes more acidic and safer against bacterial spoilage. Calcium chloride, a firming agent, is used during the manufacturing process to help retain the tomatoes’ texture. As calcium chloride is classified as part of the manufacturing process it does not have to be declared on the list of ingredients.


Passata is made from fresh plum tomatoes that have been pureed and sieved to remove the skin and seeds. Once the smooth sauce has been bottled, it’s pasteurised (gently heated) to give it a longer shelf life of a few years.


Another wonderful way to preserve the earthy rich flavour of tomatoes when fresh are scarce is to dry them to a paste. Tomatoes are cooked for hours, the skin and seeds are sieved and then further cooked to evaporate all moisture and create a paste.

Dried and semi dried (Anti pasti)

Drying some of the harvest’s abundance to use during the winter has been a way of preserving tomatoes for centuries. The Italians have turned this into an eating art form using lots of different vegetables, preserving them in oil with some garlic and herbs to create anti pasti. Not all semi dried tomato anti pasti are the same. The best quality semi dried tomatoes are harvested ripe, dried on wooden racks under the sun for a few days then bottled in oil with herbs and a touch of garlic before pasteurisation. These tomatoes still retain the sweet plumpness and concentrated flavour of their original form. One of the most delicious is the small sweet Perinos variety from Puglia.

However, supermarkets are flooded with poor quality, poor tasting dried and semi dried tomatoes. These dried tomatoes are kept in barrels of brine for up to six months before they are bottled and pasteurised. The flavour and texture contrasts sharply to those tomatoes that are bottled straight away. They are tough, chewy and can have an unpleasant, bitter, salty taste.

It’s hard to tell just by looking at a jar or deli counter platter if the dried tomatoes are the delicious ones or not. The good quality anti pasti have a vibrant red colour, are fairly plump (for a dried tomato) and tend to be a lot more expensive than the reddy brown, wizened, cheaper dried tomatoes that have sat in brine for far too long.


The very best way to enjoy fresh or cooked tomatoes is in Italian recipes. The Italian love of the tomato is extraordinary and they have perfected how to get the most flavour out of this luscious fruit.

Eaten raw in a Caprese salad, their acidity balances the creamy fattiness of Buffalo mozzarella and their sweetness counteracts the slight bitterness of the extra virgin olive oil. Fragrant, aniseed basil torn over the dish finishes off the salad. Eaten with hunks of fresh bread this makes a sumptuous meal.

A simple fresh tomato sauce eaten with the best quality dry pasta and freshly grated Parmigiano Reggiano makes a truly satisfying dinner. In Naples, the full flavoured Piennolo cherry tomato is used, but as it is neigh on impossible to find this variety outside the city, the baby plum tomato is the best substitute. Halve the little tomatoes and pan fry in extra virgin olive oil with a crushed, chopped garlic clove on a medium heat for ten minutes. The tomatoes will slowly break down and create a sauce thick enough to cling to al dente pasta. I add a teaspoon of sugar when making this sauce during the winter when the tomatoes have been starved of the sun and sometimes I even add a handful of semi dried Perinos tomatoes to add another layer of flavour to the sauce.

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