14In this work, the potential of the electrospraying technique to obtain food-grade gelatin 15 capsules in the submicron range for sensitive bioactive protection was explored, 16 studying the influence of the protein concentration on the size and morphology of the 17 obtained particles. Gelatin was selected as encapsulating material because, being 18 commonly used as a food ingredient, it possesses unique gelation properties and is 19 commercially available at a low cost. The electrosprayed matrices were used to 20 encapsulate a model antioxidant molecule, (Ð)-epigallocatechin gallate (EGCG). Very 21 high encapsulation efficiencies, close to 100%, were achieved, and the antioxidant 22 activity of the bioactive was fully retained upon encapsulation. The EGCG release 23 profiles showed a delayed release of the encapsulated antioxidant in aqueous solutions. 24 Furthermore, while free EGCG in PBS lost a 30% of their antioxidant activity being 25 completely degraded in 100 hrs, encapsulated EGCG retained its whole antioxidant 26 activity within this time period. 27 28 29 KEYWORDS 30 Electrospray, encapsulation, gelatin, antioxidant, epigallocatechin gallate, functional 31 food 32 33 Chemical compounds studied in this article: 34 (-)-Epigallocatechin gallate (PubChem CID: 65064) 35 36 3
This work reports on the production and characterization of agar-based extracts from the seaweed Gelidium sesquipedale by means of simple protocols based on hot-water and sonication treatments. The combination of sonication with the hot-water treatment reduced 4-fold the extraction time without significantly affecting the extraction yield (ca. 10-12%) and the extracts' properties. Apart from agar, the extracts contained proteins, polyphenols and minerals, which conferred them high antioxidant capacity and led to the production of brownish softer gels. The application of an alkali pre-treatment yielded almost pure agars, with higher molecular weights and crystallinities than commercial agar, resulting in stiffer gels. However, the partial digestion of agar by the alkali led to low extraction yields (ca. 2-3%). These results show the efficiency of the combined heat and sonication method to generate cost-effective agar-based extracts with potential applications within the food industry.
Electrospraying has recently emerged as a novel microencapsulation technique with potential for the protection of probiotics. However, research efforts are still needed to minimize the viability loss observed during the processing of sensitive strains, and to maximize productivity. The aim of the present work was the optimization of the electrospraying conditions for the microencapsulation of a model probiotic microorganism, Lactobacillus plantarum, within a whey protein concentrate matrix. In a pre-optimization step, the convenience of encapsulating fresh culture instead of freezedried bacteria was established. Additionally, a surface response methodology was used to study the effect of the applied voltage, surfactant concentration, and addition of a prebiotic to the formulation on cell viability and productivity. Viability losses lower than 1 log 10 CFU were achieved and the bacterial counts of the final products exceeded 8.5 log 10 CFU/g. The protection ability of the developed structures during storage and in-vitro digestion was also evaluated.
In this study, curcumin was encapsulated within electrospun protein (i.e. gelatin and zein) 15 fibers to generate bioactive coatings for food packaging. Additionally, a green tea extract (GTE) was also incorporated within the formulations to evaluate its impact on the stability, protective ability, and release properties of the curcumin-loaded fibers. Due to the poor solubility of curcumin in aqueous media, a strategy based on its incorporation through liposomes was developed, allowing to successfully incorporating curcumin into gelatin fibers. Very high encapsulation efficiencies were attained for both zein and gelatin, with the former showing an enhanced protection effect and a more limited and slower release of the curcumin in hydrophobic food simulants. The addition of GTE resulted in strong interactions being established with the proteins and, in the particular case of gelatin, it improved the protective effect and slowed down the curcumin release from the fibers, although it did not prevent their collapse in water. The results showed that while the developed gelatin coatings showed a promising release behavior in contact with fatty food simulants, zein-based coatings would be more adequate for packaging of high water content food products.
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