Image is for illustrative purposes only.
This is a blueberry mirror glaze with the body of a jam: cooked fruit, sugar and glucose thickened with a little modified starch and set with gelatine, so it pours in a smooth, glossy sheet and stays put on the side of a cake. The colour is a deep purple-blue and the flavour is fruity and lightly tart, lifted with fresh lemon juice and a pinch of citric acid.
Use it over mousse cakes and entremets that have been frozen firm, over cheesecakes, or as a shiny topping on a tart. It can also be brushed on more thinly as a fruit glaze. Warmed gently, it goes back to a pouring consistency, so a batch can be made ahead and kept in the fridge.
Ingredients
The weights in the recipe table below will yield the following 'weight per unit' and 'number of units'. If you would like to change the recipe to cater to a different 'weight per unit' and/or 'number of units',
you can use the Recipe Calculator Tool below the ingredients table.
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Weight Per Unit: 516
Number of Units: 3
Unit Size: 20 cm round mousse cake or entremet
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WEIGHT
(grams)
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ALTERNATIVE METRIC
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INGREDIENT
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IMAGE
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CONDITION
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A
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600 |
2.5 cups
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Water
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B
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200 |
7 ounces
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Frozen Blueberries
Blueberries are small, deep blue-purple berries with a mild sweet-tart flavour. Frozen blueberries hold their shape well in cooking and are sold all year round, making them a reliable choice for fillings and compotes.
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frozen |
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C
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400 |
14.1 ounces
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Sugar
Sugar is the generalized name for sweet, short-chain, soluble carbohydrates, many of which are used in food. They are carbohydrates, composed of carbon, hydrogen, and oxygen. There are various types of sugar derived from different sources. Simple sugars are called monosaccharides and include glucose (also known as dextrose), fructose and galactose. The table or granulated sugar most customarily used as food is sucrose, a disaccharide. (In the body, sucrose hydrolyses into fructose and glucose.) Other disaccharides include maltose and lactose. Longer chains of sugars are called oligosaccharides. Chemically-different substances may also have a sweet taste, but are not classified as sugars. Some are used as lower-calorie food substitutes for sugar described as artificial sweeteners.
caster
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D
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200 |
7 ounces
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Glucose Syrup
Glucose syrup, also known as confectioner's glucose, is a syrup made from the hydrolysis of starch. Glucose is a sugar. Maize (corn) is commonly used as the source of the starch in the US, in which case the syrup is called "corn syrup", but glucose syrup is also made from potatoes and wheat, and less often from barley, rice and cassava.
Glucose syrup containing over 90% glucose is used in industrial fermentation, but syrups used in confectionery contain varying amounts of glucose, maltose and higher oligosaccharides, depending on the grade, and can typically contain 10% to 43% glucose. Glucose syrup is used in foods to sweeten, soften texture and add volume. By converting some of the glucose in corn syrup into fructose (using an enzymatic process), a sweeter product, high fructose corn syrup can be produced.
43 DE
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E
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15 |
1 tablespoon
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Fresh Lemon Juice
Fresh lemon juice is the juice squeezed from whole lemons and strained of seeds and pulp. It gives a natural sharpness and aroma that bottled juice cannot match, and roughly three medium lemons will yield the amount needed here.
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strained |
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F
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25 |
0.9 ounce
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Modified Starch
Modified starch is a corn or tapioca starch that has been treated so it thickens smoothly and stays stable when acid, sugar and freezing are involved. In a glaze it gives body and shine without becoming cloudy or watery; plain corn starch can be used instead, though the set will be a little softer.
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G
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25 |
0.9 ounce
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Pure Icing Sugar
Pure icing sugar is also made from pulverised granulated sugar but contains no cornflour. For everyday cooking, icing sugar mixture does the trick; the only place where pure icing sugar is a must is when making royal icing, modelling fondant and the like.
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sifted |
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H
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40 |
1.4 ounces
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Gelatin
Gelatin or gelatine (from Latin: gelatus meaning "stiff", "frozen") is a translucent, colourless, brittle (when dry), flavourless foodstuff, derived from collagen obtained from various animal by-products. It is commonly used as a gelling agent in food, pharmaceuticals, photography, and cosmetic manufacturing. Substances containing gelatin or functioning in a similar way are called gelatinous. Gelatin is an irreversibly hydrolyzed form of collagen. It is found in most gummy candy as well as other products such as marshmallows, gelatin dessert, and some ice cream, dip and yogurt. Household gelatin comes in the form of sheets, granules, or powder. Instant types can be added to the food as they are; others need to be soaked in water beforehand.
powdered
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I
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40 |
1.4 fluid_ounces
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Water
for blooming the gelatine
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cold |
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J
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2 |
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Citric Acid
Citric acid is the natural acid found in lemons and other citrus fruit, sold as fine white crystals or powder. A small pinch sharpens the flavour of sugar syrups and helps stop them crystallising during storage.
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1547
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Recipe Calculator Tool
Using this tool, you can alter this recipe for your own requirements. Use the two fields below to generate new weights for the ingredients above.
STEP 1. Enter your Custom Weight Per Unit
The 'Custom Weight Per Unit' is already loaded with the weight per unit for this recipe but can be changed if required. If all you wish to do is change the number of units (or servings), just leave the current weight per unit.
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STEP 3. Click Calculate
The new weights for your adjusted recipe will be displayed in the table above.
Method
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STEP
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ACTION
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DETAIL
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CONDITION
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1 |
Prepare |
Sprinkle H (gelatine powder) over I (cold water) in a small bowl and stir once. Leave it to stand. |
Gelatine fully swollen and spongy, no dry grains |
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2 |
Mix |
In a separate small bowl, stir F and G (modified starch and icing sugar) together dry, then whisk in a few spoonfuls of cold water to make a smooth slurry. |
Smooth and lump free; the icing sugar keeps the starch grains separated |
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3 |
Boil |
Put A, B, C and D (water, frozen blueberries, caster sugar and glucose syrup) into a saucepan and bring to the boil over medium heat, stirring until the sugar and glucose have dissolved. |
Berries broken down and the syrup a deep purple |
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4 |
Thicken |
Stir the starch slurry once more and whisk it into the boiling fruit syrup. Cook, stirring, for about a minute. |
Thickened to a light jam consistency and no longer cloudy |
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5 |
Flavour |
Take the pan off the heat and stir in E and J (fresh lemon juice and citric acid). |
Fully dissolved; the flavour sharpens and the colour brightens |
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6 |
Dissolve |
Add the bloomed gelatine to the hot mixture and stir until it has melted through completely. |
No lumps or strands of gelatine visible |
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7 |
Blend |
If the glaze is not smooth enough, blend it with a stick blender, keeping the head under the surface, then pass it through a fine sieve. |
Glossy and even, with as few air bubbles as possible |
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8 |
Cool |
Cover the surface with cling film touching the glaze and leave it to cool. |
Down to about 30–35°C (86–95°F), thick but still pouring freely |
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9 |
Glaze |
Stand the frozen cake on a rack over a tray and pour the glaze over in one steady movement, starting in the centre and working outwards. Let the excess run off, then lift the cake onto its board. |
An even, shiny coat with no bare patches; the run-off can be strained and re-used |
Important Notes
Makes about 1,547 g of glaze, enough for two to three 20 cm round mousse cakes or entremets, including the run-off that drips into the tray. The cake must be frozen solid and its surface perfectly smooth before glazing, or the glaze will slide or set with ridges. Blend the glaze if it is not smooth, as the chef notes, but keep the blender head submerged so you do not beat in air bubbles. Strain the run-off through a fine sieve and it can be used again. Store the glaze in a covered container in the fridge for up to a week, or freeze it; re-warm gently over a water bath or in short microwave bursts and bring it back to about 30–35°C (86–95°F) before pouring.
Tools & Arrangements
Medium saucepan, whisk, small bowls, fine sieve, stick blender, digital thermometer, cooling rack and a tray to catch the run-off, palette knife, cling film
