RESUMOA elaboração do suco de uva em pó representa uma alternativa interessante no sentido de melhorar a conservação do produto, sendo a produção de sucos de frutas em pó uma aplicação de crescente interesse industrial. O produto seco apresenta um aumento da sua vida útil e maior disponibilidade, porém, o processo de atomização é dificultado devido ao comportamento pegajoso que as frutas exibem quando submetidas às variações de umidade e temperatura. É de grande importância para a indústria melhorar o desempenho do processo de secagem por atomização, a fim de obter produtos com melhores características, bem como aumentar o rendimento. Uma alternativa para otimizar o processo é adicionar agentes carreadores, que também possuem a função de encapsulantes. O objetivo deste trabalho foi avaliar a estabilidade e qualidade de sucos de uva em pó obtidos através spray drying, utilizando combinações de maltodextrina (MD) com proteína isolada de soja (SPI) ou proteína concentrada de soro de leite (WPC) como agentes carreadores, visando a proteção das antocianinas e obtenção de um produto com boa estabilidade. A amostra SPI 1, após 90 dias de exposição à luz, apresentou maior retenção de antocianinas, com perda de apenas 28 % do conteúdo inicial, com menor ganho de umidade e menor variação na coloração do suco em pó. A utilização desses agentes carreadores resultou em pós mais estáveis ao armazenamento, sendo promissores como encapsulantes.

Considering the antimicrobial effect of oregano essential oil, this work aimed to investigate the influence of its encapsulation in alginate beads, subjected or not to electrostatic interaction with whey proteins, wet or freeze dried, in the oil release kinetics in liquid medium simulating a meat marinating solution. Alginate beads presented loading and retention capacity between 64.19%-78.64% and 57.58%-73.26%, respectively. Freeze-drying resulted in shrunk and irregular shaped particles, with higher polydispersity in size distribution, increasing release rates. Swelling studies revealed that freeze-dried beads rapidly attained similar particle sizes of wet beads. Electrostatic interaction with proteins caused a slight reduction in porosity of freezedried beads and a slowdown effect on the release kinetics. The power law model showed good fittings to experimental release profiles and the model exponent values in the range of 0.29 to 0.33 indicated that oil release occurred mainly by Fickian diffusion. Practical applications This study shows the influence of coating and freeze-drying processes in the release kinetics of encapsulated oregano essential oil. The alginate beads present high amounts of oregano essential oil and, therefore, can be used as a natural antimicrobial. It is important to know the influence of these processes on alginate beads with encapsulated oregano essential oil, because these factors affect its release profile, reducing or extending its effect. Knowing the behavior of these beads in liquid medium simulating a meat marinating solution after these processes is very important in order to ensure a longer release kinetic, thus improving the effect of oregano essential oil, especially during its release, and enabling its use in food industry. How to cite this article: Gallo TCB, Cattelan MG, Alvim ID, Nicoletti VR. Oregano essential oil encapsulated in alginate beads: Release kinetics as affected by electrostatic interaction with whey proteins and freeze-drying.

In this study, grape juice powders from cultivar BRS Violeta was produced through spray drying. The influence of water activities on physical–chemical properties of powder, and the light stability of anthocyanins microcapsules were investigated. Evaluations of sorption isotherms, stickiness, and light stability of the anthocyanins microcapsules were carried out throughout 90 days. Blends of soy protein/maltodextrin and whey protein/maltodextrin in different concentrations and proportions were used as carrier agents. The Brunauer–Emmett–Teller and Guggenheim–Anderson–de Boer models were fitted to data of water adsorption, and the curves were classified as type II. The compression force was strongly dependent on water activity. The encapsulation matrix formulated with 10% soy protein and applied at CACof 1.25 g carrier agent/g soluble solids of the juice (1SM) resulted in the less hygroscopic powder, with a higher compression force, lower stickiness, and better anthocyanin protection, consequently presenting lower total color differences during storage. Practical applications This study shows the influence of water activities on the characteristics of spray‐dried grape juice and in the stability of microcapsules. The microcapsules of BRS Violeta grape juice present high amounts of anthocyanins and, therefore, can be used as a natural colorant or as a food additive due to their antioxidant properties. It is important to know the influence of moisture and stickiness on the powders’ properties, because these factors affect the processability, handling, and stability of microcapsules, possibly reducing the product quality. Knowing the physical–chemical properties of the microcapsules formulated with different carrier agents is very important in order to ensure longer shelf life, thus enabling a variety of applications both in the food and the pharmaceutical industry.

Oregano essential oil (OEO) exhibits antimicrobial and antioxidant properties. The bioactive compounds of OEO are volatile. Thus, encapsulation helps in protecting the activity of the compound when exposed to harmful conditions such as high (or low) temperature, light, and oxygen. Encapsulation also helps to improve the dispersibility of the compound in an aqueous medium, facilitating its application in formulated food products. We studied the release kinetics of OEO microencapsulated by gelatin/gum. Arabic complex coacervation was assessed, focusing on the influence of the physicochemical properties of the aqueous release medium (temperature (4, 25, and 30 ºC), ionic strength (0, 0.5, 1.0, and 1.5 M), and pH (3.8, 4.2, and 4.8)). Their capacity to act as release triggers was also investigated. High OEO release rates were recorded in the media with high ionic strengths (74% release in 5 h), high pH (78% release in 7 h), and low temperature (71% release in 7 h). In media at a temperature above 30 ºC and pH 3.8, the coacervated structure was disintegrated. A centered face experimental design (CFD) based on 17 samples was constructed, and an empirical model was developed to predict the maximum release conditions. The highest percentage of oil (reaching up to approximately 85%) is released over longer periods of time (7 h on an average) without damaging the integrity of the microcapsule. Peppas’ model showed the best fitting for all release profiles, with R² > 0.86 and relative average residual error < 6%, indicating the domain of Fickian diffusion during OEO release.