Extração de compostos fenólicos de farinha de resíduo de ciriguela por diferentes métodos e sua estabilidade utilizando microencapsulação

Abstract

In recent decades, economic and environmental problems have caused growing concerns about the large volume of by-products generated by the food industries. Of these, the ciriguela residue (Spondias purpurea L.) stands out, which contains bioactive compounds with antioxidant properties. Therefore, this study aimed to optimize the process of extracting phenolic compounds from ciriguela residue flour (CRF) using ultrasound-assisted extraction (UAE) and compare, in relation to the content of phenolic compounds (TPC), to the extracts obtained by conventional extraction and microwave-assisted extraction. Then, the optimization of microencapsulation was performed by spray-drying the CRF extract obtained by EAU and production of the microencapsulated extract by freeze-drying (control). Physical characterization, determination of the phenolic profile by HPLC, in vitro gastrointestinal digestion, and stability analysis for 90 days at two temperatures (7 and 25 ºC) were performed with the microencapsulated extracts of CRF. The optimal condition of the EAU of the phenolic compounds of the CRF extract was obtained using an ultrasonic amplitude of 100% and a time of 15 min. The extraction process affected TPC and antioxidant activity by DPPH and FRAP, the greater the ultrasonic amplitude and the longer the time, the greater the TPC and antioxidant activity. The TPC of the spray-dried extracts ranged from 190.45 to 454.66 mg equivalent of gallic acid (GAE/g), having greater influence on the formulation of encapsulating agents. The encapsulation efficiency (EE) of the spray-dried extracts ranged from 76.83% to 99.84%. The optimized condition of microencapsulation by atomization of the extract of CRF phenolic compounds was obtained using a temperature of 150 ºC, a feed rate of 0.80 L/h and 100% gum arabic as an encapsulating agent. Moisture, solubility and hygroscopicity of the spray-dried and freeze-dried extracts did not show any significant difference. For EE and TPC there was a significant difference (p<0.05), the spray-dried extract showed higher EE and the freeze-dried extract higher TPC. In the spray-dried extract of FRC, rutin (82.69 μg g-1) was the compound found in greater quantity. While catechin (93.94 μg g-1) was predominant in the freeze-dried CRF extract. When analyzing the simulated gastrointestinal digestion of the extracts, it was observed that higher values of phenolic compounds were found after the gastric phase, and the lowest values in the last phase. Rutin was the compound that presented the highest content after digestion of the spray-dried (68.74 μg g-1) and freeze-dried (93.98 μg g-1) extracts. The scanning electron microscope (SEM) revealed that the spray-dried microcapsules had a spherical shape and smooth surface, with less deformation than the freeze-dried microcapsules with extensive wrinkles and a more serrated surface. The spray-dried and freeze-dried microcapsules, regardless of temperature (7 or 25 °C), maintained their TPC almost unchanged for 90 days of storage. The spray-dried extract of CRF showed high TPC, antioxidant property and marketing potential, aiming to use the extract as an ingredient in food enrichment and in the production of new food, cosmetic or pharmaceutical ingredients.