This article outlines five key ways acidic and lactonic sophorolipids differ, with insights drawn from Holiferm’s commercial biosurfactants: HoneySurf® HF (high acidic) and HoneySurf® LF (high lactonic).
Sophorolipids, a class of biosurfactants derived through fermentation, have emerged as key ingredients for formulators and brand owners looking to develop high-performance and sustainable personal care and HI&I cleaning solutions.
These biosurfactants are available in two primary forms, acidic and lactonic, which each offer distinct benefits depending on the use case.
Understanding the differences between these forms is essential for formulators aiming to optimize foam, mildness, solubilization, or emulsification.
1. Molecular Structure and HLB Value
The fundamental difference between acidic and lactonic sophorolipids lies in their molecular structure:
For example, acidic sophorolipids contain a free carboxylic acid group, making them more hydrophilic, while lactonic sophorolipids form an internal ester ring (lactone), resulting in a more lipophilic molecule.
This structural difference is reflected in their Hydrophile-Lipophile Balance (HLB):
| Product | Approx. HLB | Composition |
|---|---|---|
| HoneySurf HF | ~13 | ~95% acidic, ~5% lactonic |
| HoneySurf LF | ~6 | ~15% acidic, ~85% lactonic |
Based on their respective HLB values, HoneySurf HF will be more suitable for aqueous systems and high-foam applications, while HoneySurf LF, with its lower HLB, is better suited to emulsifying oils and degreasing tasks.
2. Foaming Behavior
Foam generation is a key formulation parameter, especially in personal care and household products.
Generally, acidic sophorolipids, such as HoneySurf HF, enable high foaming formulations, particularly at ≥7 pH. This higher foam profile makes the acidic sophorolipids best suited for applications such as shampoos, facial cleansers, hand wash liquids and more.
The lactonic variety, on the other hand, is an excellent low foaming surfactant. For this reason, a biosurfactant like HoneySurf LF will perform well in applications such as hard surface cleaners, rinse aids, and other products where low foam is desired (or required).
Both maintain good performance in neutral and mildly acidic conditions, but their foam profiles help determine which to use depending on product expectations.
3. Emulsification and Solubilization Performance
Both forms are effective solubilizers, but their behavior in emulsions differs based on polarity.
For example, HoneySurf HF acts as a high-HLB emulsifier and performs well in oil solubilization tasks. It has been shown to outperform polysorbate 20 and PEG-40 hydrogenated castor oil in essential oil solubilization.
The lactonic HoneySurf LF is effective in both oil-in-water (O/W) and water-in-oil (W/O) systems due to its lower HLB and lipophilic nature. It excels in degreasing formulations and emulsifies oils at lower usage levels.
In one comparative test, 0.25% HoneySurf LF matched the performance of 1% AEO in an immersion cleaning protocol — demonstrating efficient emulsification at reduced dosage.
4. pH Stability and Formulation Clarity
Formulation pH range and clarity are key considerations for both technical performance and aesthetic qualities.
- HoneySurf HF is stable and forms clear solutions from pH 3 to 10, offering broad formulation flexibility.
- HoneySurf LF is stable from pH 3 to 8, and forms clear solutions best within pH 6 to 8.
Both are cold processable and stable up to 80°C. To avoid haziness or instability in hard water, a chelating agent is recommended when working with either surfactant.
5. Functional Applications
Each form lends itself to different types of formulations based on its structure and performance profile.
HoneySurf HF (acidic-rich):
- High-foam cleansing (shampoos, facial cleansers)
- Baby care and sensitive skin products (tear-free, non-irritant)
- Makeup removal and micellar waters
- Scalp care (reduction in sebum and skin lesions)
HoneySurf LF (lactonic-rich):
- Degreasing and hard surface cleaning
- Oil-based personal care or hybrid emulsions
- Rinse aids (anti-spotting at 0.2% active)
- Acne-prone skin care (inhibits C. acnes while maintaining microbiome balance)
In rinse aid and auto dish applications, HoneySurf LF outperformed benchmarks at minimal use levels, while in personal care, it helped reduce visible oiliness and improved cleansing without over-drying.
Bonus: Shared Strengths
Despite their differences, both forms share key benefits:
- Exceptional mildness: Both are non-irritating at typical use levels, outperforming CAPB, SLES, and other “mild” surfactants.
- Microbiome-friendly: Certified for both skin and scalp; support healthy flora.
- Excellent Environmental Profile:
- 100% renewable carbon index
- Biodegradable within 28 days
- No VOCs; produced at 20–35°C
- Carbon footprint ~1.16 t CO₂ per ton active
- Certifications: COSMOS certified, vegan, non-palm, cruelty-free, Prop 65 compliant
Formulators can also achieve cost savings — performance benchmarks have shown parity or superiority at up to 8× lower concentrations compared to glucosides and ethoxylates.
Final Thoughts
Understanding the difference between acidic and lactonic sophorolipids allows formulators to better target performance outcomes — whether you’re optimizing for foam, emulsification, mildness, or sustainability.
Using a combination of both can offer balanced performance across categories.
HoneySurf HF and LF from Holiferm are proven examples of how these two forms can be leveraged in real-world formulations.
As authorized Holiferm partners, JR Hess Company can provide technical support, samples, and formulation guidance to help you put them to work.
→ Interested in testing HoneySurf in your next formulation? Contact Us to request technical data, samples, or a formulation consult.