A Guide To Using Encapsulated Sorbic Acid In Sliced White Bread
Sliced bread is an ever-popular bakery product, but it is prone to rapid microbial growth due in part to a relatively high-water activity. It also has an increased microbial load as a result of the slicing process. Our flagship preservative SorbicPlus (an encapsulated Sorbic Acid) can be used with or without other preservatives to help reduce microbial stress and prevent premature spoilage.
We carried out shelf life trials to provide information to customers who might be considering SorbicPlus for use in their formulations. We’ve included a guide on expected mould free shelf life (MFSL) for a range of dosage levels, as well as a fermentation rate guide.
Method
We tested SorbicPlus and calcium propionate (CP) in a range of dosage levels, both independently and in combination. These were added to a standard white bread formulation (aW-0.98, pH 5.3-5.5). The 400g samples were sliced, sealed, incubated at 20˚C, and checked every day for mould growth. 40 samples (2 x 20) were baked for each treatment. The MFSL is the point at which at which ≥5% of the samples in each treatment have expired due to the presence of mould.
Yeast levels were adjusted for each treatment to ensure the dough pieces proved to reach a template in approx. 55 mins.
Results
The table below shows the minimum MFSL values for the range of preservatives used in this trial.
| SorbicPlus | Calcium Propionate | SobicPlus & Calcium Propionate | |
|---|---|---|---|
| 0.2% | 7 days | Not Tested | 9 Days |
| 0.3% | 9 days | 6 days | 17 days |
| 0.4% | 10 days | 7 days | >30 days |
| 0.5% | 10 days | 9 days | Not Tested |
The graph shows the addition of yeast which was required to ensure a fermentation time of 55 mins.
Shelf life data
Discussion
The amount of yeast required to prove bread dough in 55 mins varied significantly between treatments and the amount of preservative added. We observed the lowest yeast usage in the samples prepared with SorbicPlus only. This is because the barrier materials used in SorbicPlus ensure that the yeast can ferment optimally, so extra yeast isn’t required.
The calcium propionate used in this trial was not encapsulated, which accounts for the large amount of extra yeast required when using this preservative. Blends of SorbicPlus and calcium propionate generally required the highest yeast additions to ensure a 55 min prove time. However these blends also contained the highest levels of preservative overall.
MFSL results indicated that, weight for weight, SorbicPlus is a more effective preservative than calcium propionate. A 0.3% dosage of SorbicPlus achieved the same MFSL as 0.5% of calcium propionate, while using 50% less yeast. Increasing levels of SorbicPlus past 0.4%, in this trial did not increase the MFSL.
The longest shelf life was achieved when using a combination of SorbicPlus and calcium propionate. This is likely due to the increased levels of preservative and the fact that the two preservatives, when used together, can provide mould resistance over a broader microbial spectrum.
Conclusion
SorbicPlus, when compared to calcium propionate weight for weight, allowed an increase in MFSL while decreasing yeast usage.
The greatest extensions in MFSL shelf life were made using a combination of SorbicPlus and calcium propionate.
The shelf life results seen in this trial are likely to vary depending on factors such as formulation, processing, bakery hygiene, packaging and storage conditions.
The dosage rates used in this trial are for the purposes of information only. Maximum permitted levels of additives vary for different bakery products depending on the country/region. It is important to check local regulations to ensure these are adhered to.
SorbicPlus and pH
Sorbates operate over a wide pH range, and are effective preservatives at approximately pH 6.5 or below. Most yeast leavened bakery products have pH values within this range, and so will not require pH control for SorbicPlus to function. However, lower pH values can often result in an increase in efficacy. If possible, reducing the pH value of the product using SorbicPlus may result in an increased mould free shelf life, so this should be considered for longer life products.
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