CoreShell's effect on the water absorption rate in hot and humid conditions.
Encapsulated fruit acid, typically malic and citric, is used in confectionery to ‘sand’ the outside of gummies and jellies. They are pre-mixed with sugar to provide a visually appealing coating that delivers an initial burst of sweetness and sourness. The problem with using a coating of this nature is that the confections are then particularly susceptible to moisture.
Fruit acids are highly hygroscopic and can absorb water from the air; this is especially problematic in hot and humid conditions. Upon absorbing water, the acid particles swell and become sticky, giving them a ‘wet’ look and the shelf life of the confection is reduced.
The presence of water molecules on the surface of the sweet can also enable sugar in the coating to invert. A sucrose molecule will split into glucose and fructose in the presence of water and acid. Fructose itself is highly hygroscopic and will, in turn, attract more moisture to the surface, creating a positive feedback cycle, accelerating the decline of the sweet.
To reduce the hygroscopicity of the acid, different barrier materials can be used to coat the acid particles. These coatings resist the entry of water molecules into the acid, reducing their hygroscopicity and extending the product’s shelf life. This study aimed to determine which barrier material provided the best protection.
The study compared the water absorption of encapsulated and un-encapsulated malic and citric acid when exposed to hot and humid conditions (30°C, 60 RH). In both instances, two different barrier materials were used, palm oil and GMS (glycerol monostearate). For each of the encapsulates, 90% by weight was acid and 10% barrier material. The unencapsulated acids were the same grade and granular size used in the encapsulated versions.
Method
20g of each encapsulated fruit acid and 18g of each unencapsulated acid were weighed into a plastic beaker. Each acid was weighed out three times, giving a total of 9 beakers per acid type.
- 3 x 20g – 90% Encapsulated with palm oil
- 3 x 20g – 90% Encapsulated with GMS
- 3 x 18g – Un-encapsulated
Each beaker was then placed inside an improver oven at 30C, RTH 60% for 6 hours. The weight of each beaker was recorded every hour. The increase in the weight of each beaker shows how much water each acid had absorbed.
Results
The results indicate that less water was absorbed by the encapsulated fruit acid when compared to the unencapsulated versions (Fig. 1 and Fig. 2). Using a paired T-Test, these differences were shown to be statistically significant, demonstrating that the addition of 10% barrier material is sufficient to significantly reduce the amount of water absorbed by each type of acid. This suggests that using either palm or GMS encapsulated fruit acid will extend the shelf life of a coated confection when exposed to hot and humid conditions (30°C, 60% RH) for over 6 hours.
To determine whether there was an advantage of using palm fat over GMS to encapsulate the two different acids, a paired T-Test was used to identify whether the differences were statistically significant or due to random chance. The test showed that GMS encapsulated malic acid significantly (P<0.05) absorbed more water than the palm version, indicating that the palm encapsulate outperformed the GMS version (Fig 1).
However, the palm encapsulated citric acid absorbed more water than the GMS version (Fig 2). This was the opposite result compared to the malic acid. The differences were not deemed to be statistically significant and can therefore be attributed to random chance.
Conclusion
These results demonstrate the significant positive effects of CoreShell for encapsulated fruit acid, and the water absorption rate of both malic and citric acids in hot and humid conditions. Throughout our test, the amount of moisture absorbed was significantly reduced across all acids when an encapsulation barrier was used, which should substantially improve the shelf life of the confection.
If you have any questions or would like to try our CoreShell acids with your product, you can request a sample or get in touch.
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