Ultrasound-assisted extraction (UAE) of phenolic compounds from dried edible flowers: method development and validation

ASADIN BRILIANTAMA, Dr. Widiastuti Setyaningsih STP., M.Sc; Prof. Dr. D. Miguel Palma Lovillo.

2022 | Tesis | MAGISTER ILMU DAN TEKNOLOGI PANGAN

Saat ini, edible flower kering telah menjadi salah satu kebiasaan makan gaya hidup sehat. Salah satu cara konsumsi bunga kering yang paling umum adalah infused water (tisane). Banyak penelitian melaporkan bahwa teh bunga mengandung banyak zat antioksidan terutama dari golongan senyawa fenoliknya. Penelitian ini mengembangkan metode ekstraksi baru menggunakan teknologi ultrasonik untuk mengekstraksi senyawa fenolik dari 15 edible flower kering yang paling banyak dikonsumsi di Indonesia. Beberapa faktor ekstraksi yang dipelajari pada penelitian ini diantara: pulse duty-cycle (0.2, 0.6, 1.0 s-1), suhu (10, 40, 70 °C), rasio pelarut terhadap sampel (10:1, 20:1, 30:1 mL pelarut/ g sampel), dan komposisi pelarut (0, 25, 50% metanol dalam air) dioptimasikan berdasarkan pada response surface methodology (RSM) menggunakan pendekatan Box-Behnken design (BBD). UHPLC-PDA digunakan untuk menganalisis12 senyawa fenolik target (asam 2,4,6-trihidroksi benzoat, asam protocatechuic, aldehida protocatechuic, asam p-hidroksibenzoat, asam caffeic, asam vanillic, epicatechin, p-coumaric, asam ferulic, quercetin -3-rutinosa, asam iso-ferulat, dan quercetin-3-glukosida) dalam ekstrak. Kondisi ekstraksi optimum untuk 1 g sampel adalah 30 mL pelarut (28% metanol dalam air) pada 42 °C dengan 1.0 s-1 pulse duty-cycle. Berdasarkan studi kinetika, waktu ekstraksi optimal adalah 10 menit. Metode ini divalidasi dengan presisi tinggi (CV kurang dari 7%) dan akurasi (82% flavonoid, 83% turunan asam sinamat, dan 91% turunan asam benzoat). Selain itu, ekstraksi berbantuan ultrasonik yang diusulkan telah berhasil diterapkan untuk menentukan kadar senyawa fenolik dalam 15 edible flower kering.

Nowadays, dried edible flowers have become one of the eating habits of a healthy lifestyle. The most common way to consume dried flowers is infused water (tisane). In addition, many published studies of floral tea contain antioxidant substances mainly due to their phenolic compounds. This work had developed new extraction using ultrasound technology to determine phenolic compounds in 15 most consumed edible flowers in Indonesia. Several extraction factors including pulse duty-cycle (0.2, 0.6, 1.0 s-1), temperature (10, 40, 70 °C), solvent to sample ratio (10:1, 20:1, 30:1 mL of solvent/g of sample), and solvent composition (0, 25, 50% methanol in water) had been optimized based on a Box-Behnken design coupled with response surface methodology. UHPLC-PDA had been employed to quantify 12 major phenolic compounds (2,4,6-trihydroxy benzoic acid, protocatechuic acid, protocatechuic aldehyde, p-hydroxybenzoic acid, caffeic acid, vanillic acid, epicatechin, p-coumaric, ferulic acid, quercetin-3-rutinose, iso-ferulic acid, and quercetin-3-glucoside) in the extracts. The optimum extraction conditions for the 1 g sample were 30 mL of solvent (28% methanol in water) at 42 °C with 1.0 s-1 of pulse duty-cycle. Based on the kinetic study, the optimal extraction time was 10 min. The method was validated with high precision (CV less than 7%) and accuracy (82% of flavonoids, 83% of cinnamic acid derivatives, and 91% of benzoic acid derivatives). Additionally, the proposed ultrasound-assisted extraction had been successfully applied to determine the levels of phenolic compounds in 15 dried edible flowers.

Kata Kunci : Box-Behnken design, method development, UHPLC, tisane, validation