JOURNAL OF COSMETIC SCIENCE 240 within 12 mo of opening, known as the period after opening (27). These recommenda- tions were used as a guideline for interpreting the results of the stability testing. Initial and fi nal measurements for L*, a*, c*, h°, and dE* all formulas can be seen in Table IV. Although individual variations occurred within groups and between formulations, some gen- eralizations can be observed. Overall, increased stability was shown with formulations con- taining cyanidin (elderberry) and acylated cyanidin (purple corn and purple sweet potato). Changes in lightness (L*) were minute for all formulas across all treatments (2.5). All samples were slightly darker at the conclusion of the 12 weeks at 45°C. Changes in red- ness (a*) of the samples were not statistically signifi cant (p value  0.01) for all treat- ments, with the exception of the red radish formula at 37° and 45°C. The elderberry and purple corn formulations showed the smallest changes in a* across treatments, and the red grape and red radish showed the greatest changes. Changes in chroma (c*), followed a similar pattern with changes in a*, with the smallest changes observed with the elder- berry and purple corn lipsticks. Interestingly, both elderberry and purple corn formulas showed increased color intensity at 20°C after 12 weeks. T able IV Initial and Final CIELab Color of ACN-Lipstick Formulations at Accelerated Environmental Testing Conditions Elderberry Purple sweet potato Temperature L* a* c* h° ΔE* Temperature L* a* c* h° ΔE* Initial 29.09 1.80 2.41 318.64 0.00 Initial 29.98 6.43 6.45 361.61 0.00 -20°/20°C 29.33 2.39 2.92 325.40 0.73 -20°/20°C 31.98 6.14 6.16 355.90 0.66 20°/37°C 29.18 1.94 2.47 321.98 0.26 20°/37°C 30.22 5.53 5.54 359.36 1.09 20°C 28.78 3.07 3.31 338.45 1.78 20°C 31.54 5.85 5.89 354.17 1.99 37°C 27.40 2.99 3.19 339.29 1.97 37°C 30.18 4.28 4.40 346.65 2.80 45°C 27.99 1.94 2.29 328.24 1.27 45°C 28.82 4.52 4.57 351.43 2.36 Purple carrot Red grape Temperature L* a* c* h° ΔE* Temperature L* a* c* h° ΔE* Initial 33.63 7.97 8.01 354.44 0.00 Initial 35.30 9.66 9.66 1.42 0.00 -20°/20°C 33.95 7.55 7.61 353.27 0.93 -20°/20°C 34.85 9.47 9.47 0.59 0.41 20°/37°C 33.76 7.22 7.28 352.53 0.44 20°/37°C 34.88 9.16 9.16 0.81 0.33 20°C 32.85 9.25 9.27 356.63 1.28 20°C 36.88 9.25 9.27 3.33 0.89 37°C 33.93 8.87 8.92 355.25 1.07 37°C 33.00 8.94 8.96 2.79 1.65 45°C 32.09 6.29 6.45 347.25 3.21 45°C 32.82 6.95 6.96 0.19 3.95 Purple corn Red radish Temperature L* a* c* h° ΔE* Temperature L* a* c* h° ΔE* Initial 28.65 3.72 3.77 350.45 0.00 Initial 29.37 13.75 14.20 14.34 0.00 -20°/20°C 29.54 4.08 4.13 350.72 0.81 -20°/20°C 30.54 13.07 13.45 13.51 0.68 20°/37°C 28.83 3.67 3.73 350.34 0.38 20°/37°C 29.97 12.15 12.35 10.26 1.76 20°C 27.42 4.81 4.83 355.92 1.65 20°C 29.47 11.62 11.82 10.42 1.80 37°C 26.75 3.77 3.83 354.52 1.68 37°C 28.48 9.57 9.66 7.68 3.83 45°C 27.09 3.90 3.94 352.35 1.18 45°C 28.75 9.22 9.30 7.36 4.22 Measurements presented for cycling conditions (-20°/20°C and 20°/37°C) are after six 48-h cycles. Measure- ments shown for constant accelerated conditions (20°, 37°, and 45°C) are after 12 weeks incubation. All re- sults shown are means (n = 9).

ANTHOCYANINS AS NATURAL ALTERNATIVES TO SYNTHETIC COLORS FOR LIPSTICK 241 Changes in hue angle varied between formulations, with the greatest changes observed with the elderberry and purple sweet potato formulas. The elderberry lipstick hue angles increased for all conditions, toward a more red hue angle. Conversely, the purple sweet potato lipstick hue angles decreased for all conditions, toward a more purple hue angle. The red radish lipstick hue angles also decreased for all conditions, toward a more red hue angle. Very little changes were observed in hue angle for purple carrot, red grape, and purple corn formulations. Delta E (ΔE*), or the total color difference, can be used to quantify changes in color (28). Just noticeable differences in color can be detected at a Delta E around 2.36 however, unexperienced observers notice differences in color when the Delta E is between 3.5 and 5 (28). Ten weeks at 45°C is considered a predictor for shelf stability of 2 year (24) there- fore, some color changes were expected by week 12. Red radish formulations showed the greatest ΔE* after 12 weeks at 45°C (ΔE*: 4.22), and elderberry and purple corn formu- las showed the smallest ΔE* after 12 weeks at 45°C (ΔE*: 1.27 and 1.18, respectively). Based on the detection limits of color differences, it was determined that the color changes recorded for the formulas at all conditions were within acceptable limits therefore, shelf stabilities of at least 2 year were predicted. In addition, the samples were stored in such a way to mimick an opened container, which increases the assurance of their stability. CHANGES IN TOTAL MONOMERIC CONTENT The recovered percentage of monomeric ACN content for the formulations were deter- mined based on the initial monomeric content by weight, after the accelerated environ- mental testing. In general, the highest recovery was seen for the freeze/thaw cycles for all formulations, with a recovery of 98.91% (±0.22) for purple corn to 91.72% (±0.18) for red grape. The recovery at 45°C was the lowest for all formulations, with a recovery of 93.81% (±0.24) for purple corn to 59.11% (±1.40) for red grape. The recovery rates for the formulations followed the same pattern for all accelerated environmental testing. In order of highest recovery the formulations were purple corn, purple sweet potato, elder- berry, red radish, purple carrot, and fi nally red grape (See Figure 1). Overall, the percentage of recovered ACNs from the formulations followed a similar pat- tern shown with the color measurements reported previously. These results were expected because of the association of changes in color with degradation, or changes in chemical structure, of ACNs (11). It is not surprising then that the formulations that showed the smallest changes in color, such as the purple corn and elderberry, should have the highest recovery of monomeric ACN content, depending on the storage conditions. It is interesting to note that although the red radish had the greatest change in color, its recovery rate was higher than that of the purple carrot or red grape for all testing conditions. This may be due to the low initial monomeric content, as seen with the purple carrot. Another possibility is that some irreversible binding occurred between the ACN and lipstick matrix, as may be the case for the red grape, which had the lowest recovery for all testing conditions. CONCLUSIONS ACNs incorporated into the matrix of lipstick formulations proved to be stable, even under the accelerated environmental testing used to predict a shelf life of at least 2 year.