Foam Stability as a Quality Parameter for Herbal Surface Cleaners: Correlation With Concentration and Storage Conditions

Foam stability-an essential quality indicator of liquid cleaning products not just in terms of a consumer feel for performance, but as an indicator of cleaning efficacy. This study focused on investigating the foam stability of neem- Azadirachta indica and lemon- Citrus limon based herbal surface cleaners at concentrations of 3%, 4%, 5%, 6% and 7% and storage temperatures 25C, 30C and 45C for 4 weeks duration with effect on foam stability monitored and evaluated weekly by test tube dilution method. All of the formulations that tested positively (stable foam above liquid level) yielded positive initial foam test-signifying the presence of triterpenic glycosides (saponins). As the duration of storage extended the rate of foam stability reduced for all of the formulations and more than anything the effect of temperature showed a significantly high influence on degradation (p<0.001) The most sensitive test was the one at 45C where foam test became negative (full collapse of foam) with 3% at week 4, whereas the most concentrated product of 7% was most resistant to complete foam collapse.