Encapsulation of Hibiscus sabdariffa Extract into Zein Nanoparticles

Abstract

A combined approach for the extraction of antioxidants from Hibiscus sabdariffa and entrapment of the extract in zein nanoparticles is proposed. Different green extraction techniques were adopted: high‐pressure and ‐temperature extraction, ultrasound‐assisted extraction, and microwave‐assisted extraction, using an ethanol/water mixture as extracting solvent. The extracts were used for the preparation of zein nanoparticles by liquid antisolvent precipitation. The impacts of process variables were investigated using response surface modeling, demonstrating that the proposed strategy allows high extract encapsulation efficiency, good particle size control, and high particle stability.

Extraction, Characterization, and Bioactivity of Phenolic Compounds—A Case on Hibiscus Genera

“…When MAE was applied, the evaluated parameters were similar between studies: solvent composition (% EtOH in aqueous mixtures), extraction time, and temperature [31,34]. However, the resulting optimum values for the mentioned parameters differed across the bibliographic results, especially for solvent composition and extraction time.…”

“…For this purpose, TPC was obtained through the Folin-Ciocalteu method by spectrophotometric measures. The optimum values of TPC in these studies ranged from 20.4 mg GAE/g extract [31] to 233.20 mg of GAE/g extract for UAE [32]. Considering the selected studies and TPC as the response variable, the most efficient extraction method would be UAE.…”

“…In general, the experimental designs of the selected literature were focused on the use of response surface methodology (RSM), considering from two to three independent variables coded at three levels, and second-order models. From the variety of design models applied, Box-Behnken (BB) with a factorial design of 3 3 or 2 3 [30][31][32] and central composite design (CCD) with a factorial design of 2 3 [33,34] were the most popular. However, central composite rotable design (CCRD) [35] and face-centered central composite design (FCCCD) [36] were also considered.…”

“…The main extraction variables to be optimized were temperature, pressure, time, solvent composition, and sample amount, among others. With the objective of efficient extraction of polyphenols and high recovery, most studies selected as response variables the extraction yield of bioactive molecules [34]; individual phytochemical concentrations [32,33]; total phenolic, flavonoid, or anthocyanin contents [30,31,36]; and antioxidant capacity [32].…”

“…In addition, in Calliari et al, 2020, the extraction conditions considered for optimization were the output amplitude (%), the extraction time (min), and the solvent composition (water-ethanol, v/v), whereas the optimized variables were TPC and TAC. Optimization was achieved by extracting for 60 min with 80% ethanol and 80% of output amplitude [31]. Nevertheless, in these studies, the optimization was evaluated through response variables measured by UV-Vis spectroscopy which, as further described in this section, may present limitations due to being a non-selective analytical technique.…”