A novel analytical approach in the assessment of unprocessed Kaffir lime peel and pulp as potential raw materials for cosmetic applications
Volatile fraction of fruits is a rich source of bioactive and aroma compounds, which can be used in the cosmetics industry after meeting relevant criteria. This is particularly evident in citrus fruits, especially in Citrus hystrix, in which the headspace consists mainly of terpenes. Due to the insufficient sensitivity of analytical methods, essential oils are used in investigations in contrast to fresh fruits. Therefore, a novel approach in the assessment of unprocessed Citrus hystrix was proposed for the first time. It was proven that the application of two-dimensional gas chromatography coupled with time-of-flight mass spectrometry combined with solid phase microextraction gives reliable results in this context. Quantitation of key aroma compounds (α-pinene, limonene, citronellal, linalool, terpinen-4-ol, myrcene, α-terpineol, and citral), in the peel and pulp of fruit after prior assessment of bioactive properties measured as total phenolic content, ferric-reducing/antioxidant power and binding to human serum albumin, gives opportunity to use Citrus hystrix as a raw material in the cosmetic industry. Terpinen-4-ol and citronellal appeared to be the most important constituents of Citrus hystrix with the highest concentrations in the peel (34.58 ± 0.75 μg/g) and pulp (66.02 ± 0.85 μg/g), respectively. Polyphenols and antioxidant activities and binding properties revealed approximately twice higher bioactivity of Kaffir lime peel than pulp. Fluorescence studies of interaction of polyphenol extracts and some volatile standards with human serum albumin (HSA) showed relatively high binding properties and the correlation between biological activity and the volatile composition. Terpenes are primarily used as components of the fragrances of new perfumes and also as additives to creams, lotions or shampoos. The natural origin of terpenes is recommended in cosmetics industry.