PRESERVATIVES


the bacteria, showing the highest number of colonies living after seven days. For both the hand cream and serum


formulations, the results show a significant level of L. brevis surviving in the cosmetics seven days after the samples were inoculated. The initial decrease of L. brevis after two hours was expected – the bacteria were grown in our micro lab under optimal conditions, and utilising specific media, yielding the greatest count of bacteria in the initial inoculum level. Once this inoculum is added to the


formulation, an environment far from ideal, with minimal protein and nutrient content, and co-ingredients that may possess weak anti-microbial properties, a substantial amount of the bacteria will not be able to survive. However, it is postulated that this initial drop in bacteria may be compensated for by simply exaggerating the inoculum level of L. brevis that is added to the formulation, in order to attain the desired count in the final probiotic product. The hand wash formulation (entry 3) shows a particularly poor survival rate, with only 20 cfu of L. brevis still alive after two hours, and an insignificant number surviving for two days. Hand wash formulations contain high levels of surfactants, many of which intrinsically contain weak antimicrobial properties. The hand wash therefore presents a difficult


environment for bacteria to colonise. This effect highlights a potential limitation to using probiotics in surfactant based formulations, such as hand wash, shower gel, and facial wash. However, surfactants generally have a narrow spectrum of activity, and their antimicrobial effect changes depending on pH value, so future work to select an appropriate surfactant system and pH value may yield more promising results. The hand cream and serum formulations


provide proof of concept that the fruit acid preservative can be used to create viable probiotic cosmetics. We have demonstrated that Iscaguard IAF provides protection against common pathogenic organisms, but does not eliminate L. brevis bacteria. Further in-house testing is ongoing in order


to understand the potential shelf life of the probiotic formulations. Accelerated stability testing at 40°C has been initiated, and the viability of the L. brevis bacteria, and absence of other microorganisms, will be monitored periodically. In addition to the above mentioned tests,


our micro lab is currently developing a bacterial balance test in order to assess the impact of an antimicrobial compound on a group of two or more bacterial species coexisting in the same environment. The test is designed to mimic the skin’s microbiota, and measures changes that take place in the levels of “good” and “bad” bacteria. Preliminary results on Iscaguard IAF show


promising signs that this preservative does not upset the balance of ‘good’ and ‘bad’ bacteria when tested in an environment containing L. brevis and Staphylococcus aureus. In conclusion, Iscaguard IAF has shown


significant promise in the development of viable probiotic cosmetic formulations, where proof of concept has been achieved in two end product formulations.


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TABLE 5: FORMULATION OF HAND WASH. HAND WASH PRESERVED WITH ISCAGUARD IAF, CONTAINING L. BREVIS


Phase Ingredients A Deionised Water


Cocoamidopropyl Betaine (30%)


Sodium Lauryl Sulfate Noodles


Iscaguard IAF Squalane Glycerin


Litsea Essential Oil Lemon Essential Oil


B C


Inoculum INCI Aqua


Cocoamidopropyl Betaine Sodium Lauryl Sulfate


Lactic Acid, Propanediol, Citric Acid, Tartaric Acid, Gluconic Acid Squalane (100% Pure Extract) Glycerin


Litsea Cubeba (Litsea) Fruit Oil Citrus Limon Peel Oil


Base (pH adjustment to 4.7) Sodium Hydroxide (10% w/w) Aqua, Sodium Chloride, L. brevis


w/w (%) 72.25


15.00 8.00


1.50 1.00 1.00


0.125 0.125 q.s.


1.00


Procedure: Mix all ingredients of Phase A together. Add phase B to adjust the pH level as required. Once at the desired pH, add Phase C while mixing slowly


TABLE 6: FORMULATION OF HAND CREAM. MOISTURISING HAND CREAM PRESERVED WITH IAF, CONTAINING L. BREVIS


Phase Ingredients


A Deionised Water Glycerin


B C


Aevum Vita 525 Iscaguard IAF Coconut Oil


Glyceryl Strearate SE Seaweed Extract Vitamin E


D Inoculum INCI Aqua Glycerin Ammonium Polyacryloyldimethyl Taurate


Lactic Acid, Propanediol, Citric Acid, Tartaric Acid, Gluconic Acid Cocos Nucifera Oil Glyceryl Stearate SE


Caprylic/Capric Triglyceride, Fucus Vesiculosus Extract Tocopherol


Base (pH adjustmant to 5.0) Sodium Hydroxide (10% w/w) Aqua, Sodium Chloride, L. brevis


w/w (%) 76.00 4.00 4.00 1.50 7.80 5.00 0.50 0.20 q.s.


1.00


Procedure: Mix all ingredients of Phase A together. In a separate vessel, mix all ingredients of phase B together. Heat both phases separately to 60°C and then add phase B to phase A at moderate shear rate using an homogeniser. Once cooled to below 45°C, add phase C and mix slowly. Add the NaOH solution to achieve the desired pH level. Once at the desired pH, add in Phase D while mixing slowly


TABLE 7: FORMULATION OF VITAMIN C SERUM. VITAMIN C SERUM PRESERVED WITH ISCAGUARD IAF, CONTAINING L. BREVIS


Phase Ingredients


A Deionised Water Vitamin C


Aevum Vita 525 Iscaguard IAF Aevum Vita 167


Lemon Essential Oil Squalane Vitamin E


B C


Inoculum INCI Aqua Ascorbic Acid Ammonium Polyacryloyldimethyl Taurate


Lactic Acid, Propanediol, Citric Acid, Tartaric Acid, Gluconic Acid Propanediol


Citrus Limon Peel Oil


Squalane (100% Pure Extract) Tocopherol


Base (pH adjustment to 4.5) Sodium Hydroxide (10% w/w) Aqua, Sodium Chloride, L. brevis


wt. (%) 85.90 7.00 4.00 1.50 0.25 0.125 0.125 0.20 q.s.


1.00


Procedure: Mix all ingredients of Phase A together while mixing slowly. Add the NaOH solution to adjust the pH level as required. Once at the desired pH (4 to 5), add in Phase C and mix slowly


The supporting microbiology data for


Minimum Inhibitory Concentrations, Total Viable Counts, and Zone of Inhibitions have shown that L. brevis is tolerant to the presence of Iscaguard IAF, whilst the preservative continues to protect the cosmetic from unwanted pathogenic species of microorganism.


It is noted that the fruit acid preservative


requires low pH environments for its antimicrobial effect. Therefore, this approach to creating probiotic formulations is limited to those with pH levels that are less than 5.5. Further work continues to expand ISCA’s portfolio of skin- friendly ingredients to include active compounds with a wider pH range in use.


23


PC July 2023 PERSONAL CARE


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