In the 20th century, jelly meant coating hams in chaud-froid sauce and aspic or serving wobbly, sweet, coloured water to children or setting a mousse. Jellied stocks or consommés were sometimes served as garnishes for foie gras or made to bind together a terrine.
Gradually, chefs have turned their backs on these dishes. Setting cake crumbs in a rubbery mass and calling it trifle no longer hits the spot.
Meanwhile, at the other extreme of cookery, the manufacturing sector, "jellifiers" and "stabilisers" have boomed. Food technologists have devised dozens of gels for the processors. Some are heat-resistant, others freeze-resistant. They can thicken and pour and set. Describe them as a sub-heading of food additives and it's easy to view them with suspicion. They don't seem quite "natural". Unfamiliar names such as Agar, Carrageenan and Xanthan sound chemical, even though they originated as seaweed or some other form of plant life.
Only a few chefs realise that these gels and gums can open up a new world of textures and flavours. They really don't have to be the exclusive preserve of the food industry.
At the Fat Duck in Bray, Berkshire, Heston Blumenthal meets the challenge of industrial gels head-on. He has learnt what each one can do, what it can do for him and how to apply it to the dishes he is constantly evolving.
At the same time, they co-exist with traditional jellies, classic recipes revived and given a new taste or colour.
Gels provide a skeleton for carrying taste. They can be soft, pliable, elastic, viscous, rubbery or brittle. The chef who knows how to handle them creatively can add a new dimension to his cooking.
Types of gel
Polysaccharide gels Polysaccharide gums and gels are made up of thousands of sugar molecules. The best-known example is the starch, "cornflour", which turns a liquid into a sauce or a pudding. There are others, mainly used by the food industry either as stabilisers or setting agents. They may be very different from each other in performance, but they are usually soluble (they dissolve in water) and, if used correctly, don't form microscopic lumps that cloud a jelly. Each acts in its own specific way. They all form a sticky network with water that sets as it cools, forming gels.
Agar (or agar agar) This is similar to Carrageenan (see below) in being a seaweed extract. Its benefit is that it gels at body temperature but is also heat resistant and melts only at temperatures above 85°C.
It's a component of the Fat Duck's cauliflower risotto - carpaccio of cauliflower, caramelised cauliflower cream and cocoa jelly.
Carrageenan Extracted from the seaweed (Chondrus crispus) of the same name.
Type: available in a range of strengths. Combined with locust gum, it's freeze-resistant.
Current uses: traditional jellies; industrial - milk products, mousses, etc.
Characteristics: water soluble solution may need blending or clarifying], sets on cooling.
The Fat Duck uses it for a tea jelly (see below) to accompany a tarte tatin. "We pass the jelly through a Millipore blender, which changes the tea from a cloudy to a clarified colour," Blumenthal says.
How it works: it dissolves in water but doesn't properly disperse, forming a cloudy liquid. Blending completes the process.
Type: It's available in a range of strengths that form soft, elastic or hard, brittle gels.
Current uses: mainly industrial - baking fillings, frostings, fruit yogurts.
Characteristics: transparent, heat-resistant, water soluble, good flavour release.
The Fat Duck uses it for red pepper jelly served to garnish a hot soup and, as Blumenthal says, "Once it's set it can be reheated and won't melt".
How it works: after gelling, the polysaccharide network encapsulates flavours in the liquid phase. The taste comes through when you bite into it or crush it in the mouth.
Pectin "Pectin is the name of a class of jellying substances that occur naturally in many fruits, especially in cores, pips and skins… The cell walls of unripe fruit contain pectose, an insoluble substance that changes to soluble pectin as the fruit ripens. However, when the fruit is fully ripe, the pectin in turn changes to pectic acid and methyl alcohol, which is why barely ripe fruit is generally best for jelly."
Tom Stobart, The Cook's Encyclopaedia.
Type: Two kinds are available. HM (high ester) pectin provides gels for sweetened fruit preserves; LM (low ester) pectin gives sets for low-sugar items
Current uses: Fruit preserves - jams, jellies - with high sugar content: not used with acid products. LM pectin, mainly for industrial food processing, is in dairy products.
Characteristics: water soluble, usually with a little sugar to aid dispersion
The Fat Duck uses it for pàté de fruits. Blumenthal: "The beetroot pàté de fruits looks like blackcurrant, so people imagine that's what it is."
How it works: When the hot, sweet solution cools, the molecules stop moving and form a network that eventually sets.
Form: either as a powder (one to two teaspoons per litre) or in liquid form for preserves.
Gelatine, meat and fish jellies
Collagen About a quarter of the protein in an animal's body is collagen. It's in bones, tendons, sheets supporting skin, even in teeth. Its molecules are bound together to form a triple helix that looks like a rope. When heated, the three strands unwind and break down. As the denatured collagen cools, it soaks up surrounding water like a sponge, forming gelatine.
Gelatine Gelatine is concentrated animal protein, extracted from connective tissue to form a kind of glue. Either in leaf or powdered form, it was the chef's stabiliser of choice throughout the 20th century. It's the binding component of aspic and manufactured jellies.
Before gelatine's widespread use, chefs relied on hartshorn shavings (from deer antlers) and isinglass (from fish bladders).
Standard quantities: 15g packet of powdered gelatine will set 500ml of liquid; 7 leaves of gelatine will set 1 litre.
How to use it: Gelatine starts to melt at 27°C. It sets at 20°C.
Soaking in water for 30 minutes before use improves solvency.
Once set, a product made with gelatine continues to stiffen. A recipe that seems ideal when first prepared can seem too hard a day later.
Jellied stocks and consommes
Any stock containing collagen will eventually set to a jelly. You just have to keep reducing the liquid. What determines the kind of jelly is the ratio of collagen-containing protein to liquid and how well it's extracted.
Some common-sense rules apply:
\ Young animal bones - veal rather than beef - are more gelatinous.
* Sinewy pieces of meat - shin rather than topside - are more gelatinous.
* The smaller you chop meat and bones, the more efficient extraction becomes.
\ Boiling will cloud a jellied stock; simmering between 70°C and 80°C is better.
In classical cookery, chefs never simmered fish stocks for more than 30 minutes to prevent the stock from extracting too much gelatine from the bones. The best clarification of a double consommé results from using minced lean shin of beef that combines good flavour and a high proportion of collagen.
All about Heston
When he first set up the Fat Duck, Heston Blumenthal did French provincial dishes. In less than six years his style has changed drastically. By looking at the chemistry of cooking he has opened a Pandora's box. Most of the Biblical rules passed down in the kitchen are, he says, "not as they seem". This questioning hasn't led him to scrap his Chef's Manual, but to analyse what happens when he browns, fries, simmers or stews.
The passion for food technology has led him to work with ingredients (and equipment) that have had a place in the armoury of research and development chefs working for the food industry, but have never found their way into Michelin-starred restaurants in the UK before.
Many of his recipes rely on accurate measurement and precise timing. His chefs, supervised by his lieutenants Garrey Dawson and Ashley Watts, have to adapt to techniques they never dreamt of when studying their Ceserani & Kinton.
What is true of his kitchen applies to his customers too. They have to confront and learn to enjoy taste experiences that may be quite alien to their expectations. Blumenthal is not in the business of bamboozling them, but he's aware how acceptance and rejection can hinge on the smallest details: "Call a dish ‘crab ice-cream' and people imagine it to be sweet; call it ‘frozen crab bisque' and they'll expect it to be savoury."
He has opened up a new front for chefs and he's the best placed to know where it's going.