Isomalt, Sugar and Fructose

Isomalt is a sugar substitute derived from sucrose, used in professional pastry for decades due to its unique properties:

• Perfect transparency: once melted and cooled, isomalt forms a crystalline mass transparent like glass. It is the star ingredient for sugar sculptures, transparent artistic pieces, "blown glass" candies, and spectacular competition decorations.
• Superior stability compared to sugar: it does not crystallize spontaneously when exposed to air, unlike traditional cooked sugar which turns white and opaque within hours. Isomalt maintains its transparency for several days or even weeks.
• Moisture resistance: less hygroscopic than sucrose, it maintains its structure even in moderately humid environments.
• Easier cooking: the cooking window is wider than for regular sugar, making it more accessible to amateur pastry chefs starting to work with sugar.
• Lower sweetening power: 50 to 60% of the sweetening power of sucrose, making it also a light sweetener for reduced sugar load preparations.
• Low glycemic index: very low glycemic index (around 2-9 depending on sources), it is partially used in diabetic pastry.

Key uses: decorative lollipops, pulled sugar flowers, edible stained glass, transparent spheres and bubbles, shiny decorations for entremets, artistic competition pieces, decorative pearls.

The glucose syrup is a thick and very viscous syrup derived from the hydrolysis of starch (corn, wheat, potato). In professional pastry, it has an essential functional role:

• Anti-crystallization: added to cooked sugar syrup, it prevents sucrose from crystallizing. This is the secret of soft caramels, nougats, marshmallows, gummy candies that remain flexible without becoming grainy.
• Softness contribution: in ganaches, glucose syrup replaces part of the chocolate to make the texture more melting and stabilize the emulsion.
• Moisture effect: hygroscopic, it helps pastries retain their freshness longer by holding moisture.
• Shine: it adds shine to glazes and coatings.
• Ice cream and sorbet: it lowers the freezing point and improves texture by preventing the formation of large crystals.

Key uses: whipped ganaches (see our vanilla whipped ganache recipe), salted butter caramels, nougats, marshmallows, mirror glazes, sorbets, gummy candies, candied chestnuts. Essential in professional pastry.

The invert sugar (marketed under the name trimoline in professional pastry) is a syrup obtained by hydrolysis of sucrose, which separates into glucose + fructose. Its properties:

• High hygroscopy: retains water in pastries, allowing them to stay moist longer. Essential for gingerbread, brioches, financiers, madeleines that need to keep their tenderness for several days.
• Increased sweetening power: about 1.2 times sweeter than sucrose, to be factored into recipe calculations.
• Delays crystallization: in ganaches, caramels, and confectionery, it prevents sugar from recrystallizing.
• Improves surface browning: it promotes the Maillard reaction, thus the golden browning of pastries in the oven.
• Compatible with fermentation: in leavened doughs, it can replace part of the sugar without hindering yeast activity.

Star uses: financiers (see our financiers recipe), madeleines, gingerbread, brioches, long-lasting ganaches, salted butter caramels, long-lasting soft cakes, glazes.

In pastry, fructose is used for its higher sweetening power than sucrose (about 1.3 times sweeter). This allows:

• Sweeten at a reduced dose: less fructose by weight for the same sweet taste as sucrose. Useful for carbohydrate-controlled diets.
• Improved texture: desserts with fructose have a slightly moister, more melting texture.
• Faster browning: it caramelizes at a lower temperature than sucrose, which can speed up browning in the oven. Watch carefully to avoid burning.
• Moderate glycemic index: about 20-25, which is significantly lower than sucrose (60-65).

Limitations: fructose is more expensive than sucrose and its use is limited to specific technical recipes (confectionery, diet biscuits, certain ice creams). It is not a universal sugar substitute in all recipes.

Note: fructose is also a natural component of fruits and honey, which explains its use in some traditional recipes (especially honey gingerbread).

Here is a quick guide to identify the right technical sweetener for your pastry project.

• Transparent sugar sculptures and decorations: isomalt without hesitation. It is the only one to provide this lasting crystalline transparency.
• Soft caramels, nougats, marshmallows, gummy candies: glucose syrup. Prevents crystallization and adds softness.
• Chocolate ganaches (all variants): glucose syrup added to chocolate to stabilize the emulsion.
• Gingerbreads, brioches, financiers, madeleines (long shelf life): inverted sugar / trimoline. Keeps softness for several days.
• Mirror glazes: glucose syrup + inverted sugar combined for shine and flexibility.
• Ice creams and sorbets: glucose syrup or trimoline to prevent crystal formation and improve texture.
• Diabetic or low glycemic pastry: isomalt (very low GI) as a partial sugar replacement.
• Confectionery with maximum sweetening power: fructose in reduced doses.

Many professional recipes combine several technical sugars in the same preparation to benefit from cumulative effects. A well-made vanilla whipped ganache typically contains sucrose + glucose + sometimes trimoline.

Isomalt is technically easier to master than traditional cooked sugar but still requires some precautions.

1. Weigh precisely: follow the recipe quantities to the gram. An accurate probe thermometer is essential.
2. Cooking without water or with very little: isomalt melts directly dry in a heavy-bottomed pan, or with a few spoons of water (maximum 10-20% of the isomalt weight). No need to add more moisture, unlike traditional cooked sugar.
3. Gradual heating: start on medium-low heat and monitor the temperature with a thermometer. Target cooking temperature 165-170°C for sculptures and candies.
4. Coloring: add a powdered colorant directly into the melted isomalt, or use a high-temperature resistant gel colorant. Gently mix with a spatula.
5. Pouring: pour the melted isomalt into silicone molds (high temperature compatible) or onto a clean silicone mat. Work quickly, as isomalt starts to set as soon as the temperature drops below 100°C.
6. Pulled sugar work (sculptures): let isomalt cool until it becomes workable but still plastic (around 90-100°C). Use heat-resistant latex gloves to handle it. Stretch, fold, shape as desired.
7. Final cooling: let cool at room temperature, away from humidity (dry climate ideal). Once solidified, isomalt forms a very hard transparent crystalline mass.

See our isomalt flower lollipops recipe for a step-by-step guided example.

These two sweeteners have precise dosages depending on the recipes. Some general guidelines for your preparations.

• Chocolate ganaches: about 10 to 15% glucose syrup relative to the cream weight. For 200 g of cream, 20-30 g of glucose.
• Soft caramels: count 20 to 30% glucose syrup relative to the sugar weight, to prevent crystallization.
• Mirror glazes: typically 10 to 15% glucose and 5-10% invert sugar in the total formula, combined with sugar + white chocolate + cream + gelatin.
• Leavened doughs (brioche, viennoiseries): 2 to 5% invert sugar of the flour weight to increase shelf life.
• Madeleines, financiers, gingerbreads: 10 to 20% invert sugar replacing part of the sucrose.
• Ice creams and sorbets: 20 to 30 g of glucose or trimoline per 1 liter of mix, to prevent the formation of large crystals.

Tip: store these two sweeteners at room temperature (20-25°C). Cold makes them very viscous and hard to measure. If your glucose syrup is too thick, microwave the jar for 10-15 seconds to soften it.

1. Confusing isomalt with cooked sugar: cooking curves, temperatures, and techniques are different. Do not follow a classic cooked sugar recipe with isomalt, and vice versa.
2. Overheating isomalt: above 170°C, isomalt starts to brown and lose its transparency. Stay below this threshold.
3. Storing isomalt in a humid environment: although less hygroscopic than sucrose, it eventually absorbs moisture and loses its transparency. Ideal storage is in an airtight container with desiccant packets.
4. Approximate dosing of glucose: too much glucose and the ganache remains too liquid, too little and it becomes hard. Respect the percentages down to the gram.
5. Refrigerating glucose: it becomes very viscous and impossible to measure. Always keep at room temperature.
6. Confusing fructose and sucrose in recipes: fructose caramelizes at a lower temperature, so fructose biscuits brown faster. Watch the baking closely.
7. Overdosing invert sugar: beyond 30-40% of total sugar, the dough becomes sticky and difficult to work with.
8. Child safety: isomalt melted at 165°C causes severe burns on contact. Strictly adult handling with thermal precautions.

• Isomalt crystals: store at room temperature in an airtight container, protected from moisture. Can last several years.
• Pieces made of melted and solidified isomalt: store in an airtight box with desiccant packets, lasting from several weeks to several months depending on ambient humidity. Avoid temperature fluctuations.
• Glucose syrup: store at room temperature in its original jar. Lasts several years. Do not refrigerate (becomes impossible to handle).
• Invert sugar / trimoline: store at room temperature in its original jar, protected from moisture. Lasts several years.
• Powdered fructose: store at room temperature in an airtight container, like regular sugar.
• Food safety: all these products comply with European food standards. The best before dates indicated on the packaging must be respected.

Patissland is one of the largest French stores specializing in equipment and ingredients for creative and professional pastry. Our technical sugars section includes special sweeteners essential for professional pastry (isomalt, glucose syrup, invert sugar / trimoline, fructose), in various formats suitable for both amateur and professional use.

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