Effect of the Rare Sugar D-Allulose on Hardening of Starch Gels during Refrigerated Storage

The problem behind the study

If you make refrigerated starch-based foods, you own this problem. A starch gel is smooth when it comes out of the kettle. Leave it in the cooler overnight, and it firms up. Puddings lose their spoonable texture. Pie fillings turn rubbery. The usual culprit is amylopectin recrystallization, a slow re-association of starch chains. Sugar helps, but sugar brings calories and sweetness limits. D-allulose offers a different option. This paper, published in Foods (2024, 13, 2183), tested whether the rare sugar can slow gel hardening.

What the researchers did

The team made starch gels rich in amylopectin. They added D-allulose or sucrose, then stored the gels under refrigeration and measured hardness over time. They also looked at the hydrogen bond network inside the gels.

That second step matters. Gel firmness is not only about starch concentration; it depends on how starch molecules organize. Amylopectin recrystallization requires intermolecular hydrogen bonds. If those bonds stay loose, the network stays flexible.

This is where allulose stands out. In the tested gels, D-allulose suppressed hardening more effectively than sucrose. It reduced the proportion of intermolecular hydrogen bonds and increased the proportion of loose hydrogen bonds. In plain terms, it kept the starch network from locking into a rigid structure.

Key findings

The headline result is simple: D-allulose beat sucrose in slowing starch gel hardening. The mechanism points to hydrogen bond rearrangement. Allulose altered the balance of bond types in the gel, making recrystallization harder.

Attribute	Sucrose	D-allulose
Hardening suppression in amylopectin-rich gels	Weaker than allulose	Stronger
Intermolecular hydrogen bond proportion	—	Decreased
Loose hydrogen bond proportion	—	Increased
Sweetness	Reference	~70% of sucrose
Calories	Reference	~10% of sucrose
Regulatory status	Conventional sweetener	FDA GRAS

The sweetness and calorie numbers are worth repeating. D-allulose delivers about 10% of the calories of sucrose, with roughly 70% of its sweetness. It also carries GRAS status in the U.S. Those properties make it attractive beyond texture. If you replace part of the sucrose in a formulation, you cut calories without relying on high-intensity sweeteners alone.

What it means for manufacturers

Formulators can treat D-allulose as more than a bulk sweetener. This study suggests it can play a structural role in refrigerated starch systems. That is useful for reduced-sugar puddings, pastry creams, and fruit fillings where sucrose is removed and texture often suffers.

Because allulose is about 70% as sweet as sucrose, you may need to adjust sweetness with a high-intensity sweetener or by increasing the allulose level. But the textural benefit is not tied to sweetness. The effect comes from how allulose interacts with starch chains and water. That means it can work in savory products too, or in systems where sweetness is already balanced.

If you work with high-amylopectin starches, pay close attention. This study gives you direct evidence that allulose can delay the firming that makes those products less appealing. It does not solve every shelf-life problem, but it targets the specific mechanism behind cold-storage hardening.

Frequently asked questions

Is D-allulose approved for food use in the United States?

Yes. The FDA has designated D-allulose as GRAS. That simplifies sourcing and labeling for commercial products.

Does D-allulose taste like sugar?

It is about 70% as sweet as sucrose. The calorie content is roughly 10% that of sugar. You may need a sweetness booster if you want to match a full-sugar reference.

Will allulose keep a starch gel soft forever?

No. This study measured refrigerated storage, not infinite shelf life. Allulose slowed hardening during storage, but you still need to validate your own product. Fat, protein, water activity, and other ingredients all affect gel behavior.

Where to go from here

Allulose has been on the radar for sugar reduction. This study gives formulators another reason to test it. It fights the textural damage that happens when starch-based products sit in the cold. That is not a small thing. Refrigerated desserts live or die by mouthfeel, and mouthfeel starts with the starch network. Allulose keeps that network softer, with fewer calories than sugar. Try it in your next gel system. The data says it can work.