INSECT FATS FOR COSMETICS 199 PROOF OF PRINCIPLE: A HAND CREAM PREPARATION A hand cream was prepared to assess the physical stability of the cream and the effi cacy of the preservative system when using insect fats. These are two important criteria any cos- metic product should meet before being placed on the market. No perfume was added to monitor any changes in odor more carefully. Various fat concentrations ranging from 1% to 10% (w/w) were tested to evaluate the physical stability and sensorial properties of the cream as a function of fat concentration. As the fat concentration was increased the color of the cream darkened and the specifi c fat odor became more pronounced. This was particularly the case at 10% fat, which resulted in a hand cream with undesirable organoleptic properties. The stability was tested by storing the creams at 5°C, 21°C, and 45°C for 2 mo and monitoring the color, scent, viscosity, pH, and general aspect (i.e., whether or not a phase separation can be observed) at various time points. The 5°C and 45°C conditions repre- sent enhanced aging conditions that allow a prediction of the long-term product stability at ambient conditions. Table VII summarizes the stability results for the cream contain- ing 5% fat, which are representative for all other concentrations tested. The odor and color values at 21°C can also be taken as the initial reference values. Overall the emulsions remained homogeneous and there was no signifi cant change in the viscosity or pH value of the cream. Only in the case of creams with BSF fat was a slight syneresis observed after 4 wk at 45°C. This suggests that the long-term stability of Table VI Spreadability of Insect Fats on Gelatin Films Species Spreadability (mm) Std. Dev. Cricket 6.07 (8) 0.2 Locust 5.86 (8) 0.2 BSF 6.44 (4) 0.6 Mink 8.76 (4) 0.9 Macadamia nut 8.08 (4) 0.4 The reported values are averages and the number of measurements is given between brackets. Table VII Stability of 5% Insect Hand Creams after 2 mo Cream Odor Color Aspect Remark 5°C 21°C 45°C 5°C 21°C 45°C 5°C, 21°C, 45°C Locust raw ++ ++ ++ 7 7 8 Homogeneous Discoloration Cricket raw -- - ++ 2 3 3 Homogeneous BSF raw - - + 3 2 3 Homogeneous Slight syneresis at 45°C Cricket decolored -- - - 1 2 2 Homogeneous Locust decolored ++ ++ ++ 6 7 7 Homogeneous Discoloration Locust decolored/ deodorized -- -- -- 6 7 7 Homogeneous Discoloration BSF deodorized + - + 3 2 3 Homogeneous Slight syneresis at 45°C Color scale: 1 = white to 10 = dark yellow (or green in case of locust fat). Odor scale: -- Negligible smell - Odor noticeable, but not off-putting + Odor noticeable and slightly off-putting ++ Clear, off-putting odor.

JOURNAL OF COSMETIC SCIENCE 200 these creams may pose an issue. Nevertheless, this can likely be solved by making slight modifi cations to the cream’s composition. The color of the creams was unchanged after 2 mo except for those containing locust fat. Here a discoloration of the cream from greenish to white at the emulsion–air interface was observed. Addition of an antioxidant (0.25% sunfl ower seed oil extract of rosemary leaf) countered this effect, indicating that the dis- coloration is due to oxidation, presumably of the chlorophyll present in the fat. The fi nal preservative effi cacy was tested only on a hand cream containing 5% insect fat. This is the standard concentration when using mink or macadamia nut oil. The microbial stability of the cream, or preservative effi cacy, was assessed by a challenge test according to the European Pharmacopoeia (21). All creams containing insect fats passed the challenge test according to the A-criteria as all inoculated microorganisms are killed within a certain time and there is no proliferation of microorganisms. This is illustrated in Figure 3, which shows the microorganism reduction plot as a function of time for P. aeruginosa and A. brasiliensis. The curves for the other microorganisms tested overlap with that of P. aeruginosa. This implies that the insect fats do not interfere with the preservative system. CONCLUSIONS Insects have the potential to provide a durable source of biomaterials such as fats. Here we extracted fats from BSF, crickets, and locusts and implemented them in a hand cream Figure 3. Microorganism reductio n in locust hand cream after inoculation according to the European Phar- macopoeia (21). Symbols: P. aeruginosa ( ) and A. brasiliensis ( ).