The use of propolis as a dietary supplement or as an ingredient in different food products is increasing, due to its antioxidant and bactericidal properties. These nutritional properties directly depend on its phenolic composition. For this reason, this study analysed the total contents of flavones and flavonols, flavanones and dihydroflavonols, and the antioxidant capacity by using the methods of ABTS and linoleic acid/β-carotene in 99 samples of propolis from Spain and Chile. A rapid method was developed for quantifying these parameters in raw propolis using near infrared (NIR) spectroscopy with a remote reflectance fibre-optic probe applied directly to the ground-up sample. The models developed allow for the determination of the total flavones and flavonols (0–183 mg quercetin/g propolis and 0–72 mg rutin/g propolis), of the total flavanones and dihydroflavonols (9–109 mg pinocembrin/g propolis extract), and of its antioxidant capacity by the ABTS method based on the reduction of the 2.2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation(0–3212.6 nmol Trolox/mg of propolis) and of linoleic acid/β-carotene (22–86% inhibition). The NIR spectroscopy models were applied in external validation to different samples of the calibration group, which led to the conclusion that the methods developed provide significantly identical data to the initial chemical data of reference.

In this study we analyzed the phenolic composition of 50 propolis extracts from Spain and Chile by high performance liquid chromatography (HPLC). Ten compounds were identified and quantified: caffeic acid; p-coumaric acid; cinnamic acid; ferulic acid; isoferulic acid and 3,4-dimethyl-caffeic acid (DMCA); caffeic acid benzyl ester; p-coumaric cinnamyl ester; p-methoxy cinnamic acid cinnamyl ester; and caffeic acid phenylethyl ester (CAPE). The amounts of phenolic acids found ranged from 20.1–156.4 mg/g for Spanish propolis to 1.7–37.4 mg/g for Chilean propolis. Higher amounts were found for phenolic acid derivatives in all samples analyzed with values between 23.5–132.2 mg/g in Spanish propolis and 21.0–123.0 mg/g in Chilean propolis. A new method based on Near-Infrared Spectroscopy (NIR) is used to estimate the phenolic composition of acids and acid derivatives. The results obtained show that there are no differences between the results obtained by NIR spectroscopy and the chromatographic data.