Flavor retention of peppermint (Mentha piperita L.) essential oil spray-dried in modified starches during encapsulation and storage

Essential oil encapsulations: uses, procedures, and trends

Recently there has been an increased interest towards the biological activities of essential oils (EOs).

Edible coatings as encapsulating matrices for bioactive compounds: a review

Edible coatings can extend the shelf-life of many foods, controlling moisture and solute migration, gas exchange and oxidative reaction rates. Besides, edible coatings can be used as carriers of bioactive compounds to improve the quality of food products such as antioxidants, antimicrobials, flavors and probiotics. These approaches can be useful to extend shelf-life as well as provide a functional product. When edible coatings are used as a matrix holding bioactive compounds remarkable benefits arise; off odors and flavors can be masked, bioactive compounds are protected from the environment, and controlled release is allowed. In this sense, the present review will be focused on analyzing the potential use of encapsulation with edible coatings to incorporate bioactive compounds, solving the disadvantages of direct application.

Estabilidade da polpa de morango atomizada utilizando diferentes agentes carreadores

Este trabalho teve por objetivo avaliar o efeito de diferentes agentes carreadores (Maltodextrina 5DE, Maltodextrina 10DE, Goma arábica e Capsul®) nas características físico-químicas (umidade, densidade, solubilidade, teor de antocianinas e atividade antioxidante) da polpa de morango desidratada por atomização e armazenada à temperatura ambiente por 90 dias. A utilização dos diferentes agentes carreadores resultou em pós com valores de densidade aparente entre 0,40 e 0,52 g/cm³ e umidade menor do que 2,5%. Todas as amostras foram altamente solúveis, mas os pós obtidos com a Maltodextrina 5DE e com a Goma arábica apresentaram menor higroscopicidade. As isotermas de sorção obtidas foram do tipo III e o modelo de GAB foi o que melhor se ajustou aos dados experimentais. A amostra produzida com goma arábica apresentou a maior concentração de antocianinas e, consequentemente, maior valor de atividade antioxidante, tanto imediatamente após a secagem como ao longo de 90 dias de armazenamento. Os resultados obtidos indicaram que a goma arábica foi o agente carreador mais adequado para a produção de polpa de morango em pó.

Stability and bioaccessibility of β-carotene in nanoemulsions stabilized by modified starches

Oil-in-water nanoemulsions stabilized by food-grade biopolymer emulsifiers (modified starches) were fabricated using high-pressure homogenization in an effort to improve the stability and bioaccessibility of β-carotene. Physicochemical and biological properties of β-carotene nanoemulsions were investigated considering the particle size, β-carotene retention, and in vitro digestion. During 30 days of storage at different conditions, the mean diameters of the emulsion systems were increased by 30-85%. The retention of β-carotene in nanoemulsions was significantly higher compared to that of the β-carotene dispersed in bulk oil. After in vitro digestion, the bioaccessibility of β-carotene was increased from 3.1% to 35.6% through nanoencapsulation. The results also indicated that modified starch with high dispersed molecular density led to a higher retention but lower bioaccessibility of β-carotene in nanoemulsions. This could be due to the thick and dense interfacial layer around the oil droplets. This result provides useful information for developing protection and delivery systems for carotenoids.

Diverse applications of electronic-nose technologies in agriculture and forestry

Electronic-nose (e-nose) instruments, derived from numerous types of aroma-sensor technologies, have been developed for a diversity of applications in the broad fields of agriculture and forestry. Recent advances in e-nose technologies within the plant sciences, including improvements in gas-sensor designs, innovations in data analysis and pattern-recognition algorithms, and progress in material science and systems integration methods, have led to significant benefits to both industries. Electronic noses have been used in a variety of commercial agricultural-related industries, including the agricultural sectors of agronomy, biochemical processing, botany, cell culture, plant cultivar selections, environmental monitoring, horticulture, pesticide detection, plant physiology and pathology. Applications in forestry include uses in chemotaxonomy, log tracking, wood and paper processing, forest management, forest health protection, and waste management. These aroma-detection applications have improved plant-based product attributes, quality, uniformity, and consistency in ways that have increased the efficiency and effectiveness of production and manufacturing processes. This paper provides a comprehensive review and summary of a broad range of electronic-nose technologies and applications, developed specifically for the agriculture and forestry industries over the past thirty years, which have offered solutions that have greatly improved worldwide agricultural and agroforestry production systems.

Physical and antimicrobial properties of peppermint oil nanoemulsions

The mixture of peppermint oil (PO) with medium-chain triacylglycerol was emulsified in water and stabilized with a food-grade biopolymer, modified starch, to form PO nanoemulsions. The effects of emulsifying conditions including homogenization pressure, the number of processing cycles, and oil loading on the mean diameters and viscosities of nanoemulsions were characterized by dynamic light scattering, optical microscopy, and rheological measurements. The formulated PO nanoemulsions with mean diameters normally <200 nm showed high stability over at least 30 days of storage time. Their antimicrobial properties related to those of PO have also been evaluated by two assays, the minimum inhibitory concentration (MIC) and time-kill dynamic processes, against two Gram-positive bacterial strains of Listeria monocytogenes Scott A and Staphylococcus aureus ATCC 25923. Compared with bulk PO, the PO nanoemulsions showed prolonged antibacterial activities. The results suggest that the nanoemulsion technology can provide novel applications of essential oils in extending the shelf life of aqueous food products.

Preparation of core-shell CaCO3 capsules via Pickering emulsion templates

Micron size and food grade pristine CaCO(3) particles were used to stabilize an oil in water Pickering emulsion. The particles also acted as nucleation sites for the subsequent crystallization of CaCO(3) with the addition of CaCl(2) and CO(2) gas as precursors. After the controllable crystallization process, a dense CaCO(3) shell with a few microns in thickness was formed. The CaCO(3) shell was proven to be calcite without the presence of crystallization modifiers. The crystallization speed and the shell integrity were controlled by manipulating the addition of CaCl(2) amount during the different crystallization stages; therefore, the homogeneous nucleation in the bulk was almost inhibited, and the heterogeneous nucleation at the oil-water interface on pristine CaCO(3) particles was the main contribution to the growth of the shell. The encapsulated limonene flavor in CaCO(3) capsules showed a prolonged release in neutral water at 85°C, while a burst release at pH 2 water as expected. The method is a simple and scalable process for creating inorganic core-shell capsules and can be used for producing food grade capsules for controlling the flavor release or masking undesirable taste in mouth.

Spray-dried oil powder with ultrahigh oil content

We report a new facile route to the production of solid oil powders with an oil weight content of as high as 90% or beyond. The proposed method starts from a standard protein-stabilized oil-in-water emulsion in which a protein monolayer absorbed at the oil-water interface is successively cross linked by a thermal treatment. The emulsion is then spray dried as for ordinary emulsions, however without the addition of hydrocolloids typically needed when spray drying liquid oil dispersions. This leads to a final solid oil powder in which the total mass is constituted of oil, proteins, and eventual buffer salts and in which the elasticity of the cross-linked protein monolayer is alone sufficient to stabilize the powder and to limit any oil leakage. To best illustrate the potential in food applications and to preserve the food-grade nature of the constituents, we have used thermal denaturation at 80 °C for 15 min to cross link a β-lactoglobulin-stabilized olive oil-in-water emulsion and to produce the corresponding solid oil powder. Because of the simplicity and flexibility of the proposed pathway, the present method can be used inexpensively to convert any type of hydrophobic liquid into the corresponding solid powder and is then particularly suitable for cosmetic, pharmaceutical, medical, biotechnological, and food applications.

Chitosan coating improves retention and redispersibility of freeze-dried flavor oil emulsions

Flavor oils are often encapsulated as emulsions by drying processes such as freeze-drying or spray-drying, using mainly macromolecular emulsifiers such as gums and proteins to stabilize the emulsions during drying. The objective of the present study was to examine whether a combination of a charged small-molecule emulsifier and an oppositely charged polysaccharide adsorbed to the emulsion droplet surface can substitute commonly used encapsulation materials for the drying of flavor oil emulsions. To this end, polysaccharide-coated flavor oil emulsions were prepared by high-pressure homogenization of mixtures consisting of a flavor oil (R-carvone), a negatively charged citric acid ester small-molecule emulsifier (citrem), and various concentrations of a positively charged polysaccharide (chitosan) in acetate buffer at pH 4.0. Nanoemulsions with average particle diameters of approximately 100 nm in the absence and approximately 230-250 nm in the presence of chitosan coating were obtained. These emulsions were subsequently freeze-dried with different concentrations of maltodextrin, which served as the main encapsulation material. It was demonstrated that coating the oil droplet surface with a small amount of chitosan resulted in remarkably improved retention levels and redispersibility properties of the freeze-dried carvone emulsions. Maltodextrin content also affected both retention and redispersibility. At optimal chitosan and maltodextrin concentrations approximately 95% retention levels were obtained, and the average particle sizes of freeze-dried and redispersed emulsions were approximately 270-300 nm, as compared to approximately 230-250 nm before freeze-drying. The results demonstrate that charged small-molecule emulsifiers used in combination with oppositely charged polymers are viable alternatives to macromolecular emulsifiers for freeze-drying of flavor oil emulsions.