While flavanones exist in a variety of chemical forms, their favorable health effects are most prominent in their free form-aglycones. Their concentrations in grapefruit (Citrus × paradisi L.) extracts vary according to the extraction and hydrolysis methods used. The primary aim of this work was to maximize the yields of naringin and naringenin from various parts of fresh grapefruit fruits (flavedo, albedo, and segmental) using different extraction and hydrolysis methods. In addition, we aimed to evaluate the excipient-magnesium aluminometasilicate-and determine its influence on the qualitative composition of grapefruit extracts. Extracts were obtained by heat reflux extraction (HRE), ultrasound-assisted extraction with an ultrasonic homogenizer (UAE*), and ultrasound-assisted extraction with a bath (UAE). Ultrasound-assisted extraction using a bath (UAE) was modulated using acidic, thermal, and alkaline hydrolysis. The highest yield of naringin 8A (17.45 ± 0.872 mg/g) was obtained from an albedo sample under optimal conditions using ultrasound-assisted extraction; a high yield of naringenin 23-SHR (35.80 ± 1.79 µg/g) was produced using the heat reflux method from the segmental part. Meanwhile, ultrasonic combined with thermal hydrolysis significantly increased flavanone extraction from the albedo and segmental parts: naringin from sample 9-A (from 17.45 ± 0.872 mg/g to 25.05 ± 1.25 mg/g) and naringenin from sample 15-S (from 0 to 4.21 ± 0.55 µg/g). Additionally, magnesium aluminometasilicate demonstrated significant increases of naringenin from all treated grapefruit parts. To our knowledge, this is the first report of magnesium aluminometasilicate used as an adsorbent in flavanone extractions.
Keywords: Citrus × paradisi L.; adsorbent; aglycones; excipient; extractions; flavanones; glycosides; grapefruit; magnesium aluminometasilicate.