In this study, the influence of encapsulation process conditions on the physical properties and chemical composition of encapsulated pumpkin seed oil was investigated. Four variants of encapsulated oil were prepared: spray-dried nonhomogenized emulsions at the inlet temperatures of 180 and 130°C, spray-dried homogenized emulsion at the inlet temperature of 130°C, and freeze-dried homogenized emulsion. The emulsion was prepared by mixing 10.6% oil with 19.8% wall materials (15.9% maltodextrin + 0.5% guar gum + 3.9% whey protein concentrate) and 69.6% distilled water. The quality of encapsulated pumpkin seed oil was evaluated by encapsulation efficiency, surface oil, total oil and moisture contents, flowing properties, color, and size. Additionally, fatty acid composition, pigment characteristics, and the content of bioactive compounds (tocopherols, squalene, and sterols) were determined. Changes of these components after the encapsulation process in comparison to the control pumpkin seed oil were considered as stability parameters. The highest encapsulation efficiency was obtained by spray-drying at the inlet temperature of 130°C. Generally, the spray-drying process had a positive effect upon the physical parameters of encapsulated pumpkin seed oil but results were dependent on process conditions. The higher inlet temperature generated more surface oil, but capsules obtained at the lower temperature were greater in size and more deformed. Although freeze-drying proceeded at a very low temperature, the powder obtained with this technique was characterized by the highest bioactive compound losses (with the exception of sterols) and the lowest stability. The homogenization process applied before spray-drying affected greater polyunsaturated fatty acid, squalene, and pigment degradation. In conclusion, results of the study showed that the spray-drying non-homogenized emulsion was a more recommendable technique for the encapsulation of pumpkin seed oil because of smaller changes of native compounds and better oxidative stability.

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The effect of pressurization at different pressures (from 200 to 1000 MPa, at 200 MPa intervals, t const. = 15 min) and periods of time (from 15 to 35 min, at 10 min intervals, p const. = 800 MPa) on the changes of proteins and nitrogen compounds of skimmed milk was studied.The pressurization caused an increase in the amount of soluble casein and denaturation of whey proteins. The level of nonprotein nitrogen compounds and proteoso-peptone nitrogen compounds increased as a result of the highpressure treatment. These changes increased with an increase in pressure and exposure time. High-pressure treatment considerably affected the changes in the conformation of milk proteins, which was reflected in the changes in the content of proteins sedimenting and an increase in their degree of hydration.

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The study investigated the influence of spray-and freeze-drying on the bio-oil powder quality. The powders were characterized by process efficiency, structure, colour, oil and bioactive compounds contents, fatty acid composition and oxidative stability. Cold-pressed bio-oils of evening primrose, borage and blueweed were homogenized with wall materials and water followed by spray-drying at 130°C inlet air temperature or freeze-drying at −56°C. It was shown that lower encapsulation efficiency of freeze-drying process correlated with higher surface oil content. The content of bioactive compounds was more affected by the processes than the fatty acid composition regardless of the method of drying. The powders produced by freeze-drying had a higher tocopherol content than those produced by spray-drying. Both spray-and freeze-drying significantly contributed to the changes of sterols concentration, but the changes were greater for bio-oil powders obtained by spray-drying. Influencia del secado en emulsión sobre la composición de ácidos grasos, el contenido de compuestos bioactivos y la estabilidad oxidativa de los bioaceites encapsulados RESUMEN El presente estudio investigó la influencia del secado por atomización y liofilización en la calidad del polvo de bioaceite. Los polvos se clasificaron de acuerdo con la eficiencia del proceso, la estructura, el color, el contenido de aceites y compuestos bioactivos, la composición de ácidos grasos y la estabilidad oxidativa. Los bioaceites de onagra, borraja y hierba azul prensados en frío se homogeneizaron con materiales de pared y agua, a lo que siguió su secado por atomización a 130°C de temperatura del aire de entrada o por liofilización a −56°C. Se constató que la menor eficiencia de encapsulación atribuible al proceso de liofilización se correlaciona con un mayor contenido de aceite superficial. El contenido de compuestos bioactivos se vio más afectado por los procesos que por la composición de ácidos grasos, independientemente del método de secado utilizado. Los polvos producidos por liofilización tienen mayor contenido de tocoferol que los producidos por atomización. Tanto la atomización como la liofilización contribuyeron significativamente a los cambios registrados en la concentración de esteroles; sin embargo, se detectaron mayores cambios para los polvos de bioaceite obtenidos por atomización.

Fortification of foods with fish oil rich in n–3 fatty acids improves the nutritional value, but creates challenges with flavor and oxidative stability, especially during storage. Pea, soy, and sunflower proteins were used in combination with whey protein or maltodextrin to encapsulate fish oil by spray-drying. The use of whey protein compared with maltodextrin as wall material improved oxidative stability of spray-dried emulsions, although the use of whey protein increased the number of observed cracks in outer shell of the particles. Non- and encapsulated oil were used in cookies and chocolates to examine flavor characteristics by generic descriptive analysis and volatile products by solid-phase microextraction with gas chromatography-mass spectrometry. A long-term storage test at room temperature was conducted to evaluate the oxidative stability of the food models. Fortification changed the texture, odor, and flavor of the food models with fishy flavor being the most impactful attribute. For both food models, use of pea protein with maltodextrin resembled attributes of control the best. Fortification and encapsulation material also affected volatile profiles of food models. Both non-encapsulated oil and whey protein formulations performed well in regard to oxidative stability for both food models. Generally, the cookie model showed more potential for fortification than the chocolate one.

The aim of the study is to compare selected carbohydrates that differed in the glycaemic index: maltodextrin, three native starches (wheat, rice, maize), and two disaccharides (trehalose and lactose) used to encapsulation of model oil (in this case cold-pressed pumpkin oil). Encapsulation efficiency of pumpkin oil by spray drying, size of obtained capsules, oxidative stability of encapsulated oil, and retention of tocopherols, squalene, and sterols in surface and core material of capsules were determined. It was found that encapsulation efficiency varied from 35% for rice starch to 68–71% for wheat starch, maltodextrin, and lactose. The bulk density of capsules was independent of the used carbohydrate type (189–198 kg/m3), while their size was significantly lower for samples of pumpkin oil encapsulated in native starches (over 2 times compared to capsules with trehalose). Of the best lipid capturing agents (native wheat starch, maltodextrin, and lactose), wheat starch mainly bound tocopherols, squalene, and sterols to the capsule surface, while lactose to the core material of the capsules (35.5–81.2%). Among tested carbohydrates, native wheat starch acted as the best antioxidant agent (oxidative stability was 15.1 h vs. 9.4 h for pure pumpkin oil).