Lipid Oxidation and Degradation Products in Raw Materials: Low‐Fat Topical Skin‐Care Formulations

Abstract

Topical skin formulations with a lipid content below 15% were stored for 6 months at 5, 20, or 40 °C or for 2 weeks at 50 °C in darkness or at 20 °C with exposure to light for 6 months. The volatile lipid‐oxidation compounds formed during this storage period were compared to those formed in the raw materials during 3 months of accelerated stability storage at 40 °C. The volatile compounds were collected by dynamic headspace and analyzed using gas chromatography–mass spectrometry. It was possible to link eight out of nine volatile compounds detected during storage of topical skin formulations to the raw materials. In addition, a possible link between the appearance of butane nitrile and the decomposition of an initiator used for polyacrylate crosspolymer‐6 production was observed. The polymer may originate from texture modifiers added to the topical skin formulation or from plastics used for packaging of topical skin formulations. Furthermore, six well‐known lipid‐oxidation and nonenzymatic browning products were suggested to originate from the two raw materials, tricaprylin/tricaprin and coconut oil.

Investigation of Lipid Oxidation in the Raw Materials of a Topical Skin Formulation: A Topical Skin Formulation Containing a High Lipid Content

“…However, these were only determined for the volatile compounds that increased during storage in a PSCF. In general, we found that odor detection threshold values in PSCF were above 70 ng g −1 (Thomsen, Hyldig, et al, , in press). Therefore, in this study, we found that volatile compounds present in concentrations below 70 ng g −1 were not considered to affect product odor when present alone (3‐methylbutanal and octanal).…”

“…The odor detection threshold value for pentanal (87 ± 5 ng g −1 ) was slightly higher compared with butanal (Thomsen, Hyldig, et al, , in press). The concentration was above this level after three months storage at 20 °C with exposure to light (92 ng g −1 ) or 40 °C (104 ng g −1 ), and after six months storage at 20 or 5 °C (Fig.…”

“…The odor detection threshold value determined for butanal was 72 ± 3 ng g −1 (Thomsen, Hyldig, et al, , ). In this study, the concentration was above this level after three months storage at 20 °C, 20 °C with exposure to light, or 40 °C, and after six months at 5 °C (Fig.…”

“…a). Butanal odor in PSCF has been described as parmesan and sour dishcloth (Thomsen, Hyldig, et al, , in press).…”

“…Several studies have shown that lipid oxidation often occurs in topical skin care formulations containing unsaturated lipids, and that lipid‐oxidation products can affect product quality (Malinowska, Gliszczynska‐Swigło, & Szymusiak, ; Poyato et al, ; Thanonkaew, Wongyai, Decker, & McClements, ; Thomsen, Horn, et al, ; Thomsen, Hyldig, Taylor, Blenkiron, & Jacobsen, ; Thomsen, Hyldig, et al, ) (i.e., odor—Thomsen, Horn, et al, ; Thomsen, Hyldig, et al, , and color—Poyato et al, ), potentially impacting product both positively and/or negatively.…”