Assessment of fatty acids, amino acids, minerals, and thermal properties of bee propolis from Northern India using a multivariate approach

Abstract

First-ever, the propolis samples collected from different geographical locations of Northern India were investigated based on nutritional composition and thermal analysis. Gas chromatograph flame ionization detector (GC-FID) identified the presence of essential fatty acids: linoleic acid, α-linolenic acid, cis-11,14,17-eicosatrienoic acid, eicosapentaenoic acid, docosahexaenoic acid, γ-linolenic acid, dihomo-γ-linolenic acid, and cis-11–14-eicosadienoic acid in the samples. Additionally, first-time detection of 17 amino acids showed the presences of tyrosine, glutamic acid, threonine, arginine, lysine and aspartic acid as predominant in the samples, whereas microwave plasma-atomic emission spectroscopy (MP-AES) revealed abundance of calcium (5706.2–3121.0 mg/kg) followed by potassium (2636.0–1615.5 mg/kg), iron (2487.0–1161.2 mg/kg) and magnesium (1573.4–841.0 mg/kg). Furthermore, differential scanning calorimetry (DSC) showed major endothermic peaks at approximately 60 ᵒC demonstrating melting of long and medium chain fatty acids especially beeswax and palmitic acid, while the secondary peaks exposed vaporization of aromatic compounds. Thermogravimetric analyzer (TGA) depicted major weight loss of propolis between 270 and 470 °C and obtained 14.99–40.02% residual weight. Principal Component analysis demonstrated 99.18% variation in the first three principal components. Hierarchical cluster analysis categorized all the propolis samples successfully based on geographical locations. This study may assist quality control authorities to establish nutritional and quality standards of Indian propolis in future.