I done a lot of plant extracts with fermentation technique and I heated the extracts to 80º C degree for 2 hour. Still Bacillus contamination is here. I am using benzyl alcohol, natural acids mix and sodium benzoate in totally %1.5 concentration. But still I have contamination around 400 cfu/ml. The main source for contamination is plant. How can I handle this problem (autoclave is not possible) sodium metabisulfite will work? Thank you from now on!
Handling Bacillus contamination in plant extracts can be challenging, especially when traditional sterilization methods (such as autoclaving) are not feasible. Here are some strategies you might consider:
1. Sodium Bisulfite Sodium bisulfite can be effective against certain types of bacteria, including Bacillus. It acts as a preservative and can help reduce the microbial load. However, its effectiveness can depend on the pH of the extract and the presence of other compounds. If you choose to use it, ensure:
o Determine the appropriate concentration (usually between 0.1% and 0.3%).
o Monitor the extract for any potential sensory changes.
2. Improve Initial Raw Material CleaningSince the primary source of contamination is plant material, consider enhancing your cleaning and preparation methods:
o Cleaning: Thoroughly clean plant material before extraction to remove surface contaminants.
o Drying: Ensure plant material is adequately dried before extraction, as moisture promotes bacterial growth.
3. Alternative Preservatives Explore using other preservatives that may be more effective against Bacillus, such as:
o Potassium sorbate: Often used in conjunction with sodium benzoate.
o Essential oils: Some essential oils have antimicrobial properties; however, they may alter the flavor or aroma of your extract.
4. pH Adjustment Bacillus thrives in neutral to slightly alkaline conditions. Adjusting the pH of your extract to a more acidic level (around pH 4) can help inhibit its growth. You can use natural acids such as citric acid or ascorbic acid to achieve this.
5. Filtration Consider using microfiltration or ultrafiltration to physically remove bacteria from the extract. This method can effectively reduce the microbial load without the need for heat treatment.
6. Refrigeration Keeping the extract in a cold environment can slow down bacterial growth. Ensure the extract is stored in a refrigerator or cold room after processing.
7. Evaluate Fermentation Conditions Review the conditions of your fermentation process. Factors such as temperature, time, and the starting culture can influence the growth of Bacillus. Optimizing these parameters may help reduce contamination.
Conclusion
A multifaceted approach may be most effective. Conduct small-scale trials to evaluate the effectiveness of each method before implementing them fully.