Chitosan is widely used in the preparation of organic-inorganic composite materials, such as n-HAp/CS composites, which findapplication for bone regeneration. The methods for their preparation are various, and usually based on the preparation of intermediate n-HAp/CS dispersions, which can greatly influence the final properties of the resulting composites since it is expected that homogenous and stable dispersions lead to composite materials with improved final properties. This work hypothesizes that, additionally to process parameters such as pH, n-HAp/CS weight ratio, mixing conditions and the presence of salts, chitosan itself has a high impact on dispersions stability. Thus, the importance of properly control the preparation of the n-HAp/CS intermediate dispersions is highlighted by doing a systematic study where relevant processing parameters were studied at lab scale using ultrasonication, alone or in the presence of chitosan, namely on particle size and zeta potential. Furthermore, and based on the best laboratorial conditions, the production of n-HAp/CS nanocomposite dispersions in continuous mode was attempted through NETmix® technology,an innovative static mixer and reactor developed at the Associate Laboratory LSRE-LCM of the Faculty of Engineering of the University of Porto(FEUP).

In this work nano-hydroxyapatite/chitosan (n-HAp/CS) hybrid microparticles were prepared by spray drying following a methodology where, in a first step, aqueous nanodispersions of n-HAp in the presence of chitosan were produced by fast stirring at pH values below and above chitosan pKa (5.5 and 7.0, respectively). The mixing system used allowed the production of homogeneous and stable nanodispersions, and the subsequent spray-dried microparticles, incorporating highly pure HAp nanoparticles of approximately 50 nm, were successfully produced without degrading the organic component, chitosan. Comparatively with the n-HAp/CS-7.0, the n-HAp/CS-5.5 dispersions were characterized by a lower particle size and a higher zeta potential, being then more stable. Differences in the spray-dried microparticles were also evident from a morphological point of view. HApCS-5.5 microparticles, which present an average size in volume of 15.8 μm and n-HAp crystals homogenously distributed, were found to be preferred over the HApCS-7.0 counterparts, which require an extra step in the productive process and presented a tendency to form large agglomerates. Both prepared hybrid particles presented similar composition to that one of natural bone (HAp/CS of 70/30) and no traces of KCl salts were observed if a washed n-HAp paste was used.

Mushrooms are widely appreciated all over the world for their nutritional and pharmacological value being sources of important bioactive compounds. In this study the antioxidant potential of Suillus luteus and Coprinopsis atramentaria mushroom alcoholic extracts, and its synergistic effect, was evaluated before and after being spray-dried with maltodextrin, aiming at its exploitation as functional food ingredients. The antioxidant activity of free and spray-dried extracts was studied in vitro by DPPH radical scavenging activity, reducing power and inhibition of β-carotene bleaching (this only applied with free extracts assays). The encapsulation yield of the spray-drying process was around 50% and efficiency, determined in terms of cinnamic acid, comprised between 40-60%. The evaluation of the antioxidant activity of the combined extracts pointed out for synergistic effects.

The incorporation of mushroom extracts in food matrices configures an example of functional foods/nutraceuticals development. They are recognized as having anti-inflammatory, antitumor, antibacterial and antioxidant properties allowing the obtaining of health benefits, including disease prevention [1]. However, these extracts can present instability at high temperatures, presence of oxygen and light. Moreover, they are generally characterized by a strong odour and flavour. In this work, alcoholic extracts of two mushrooms species, Suillus luteus (SI) and Coprinopsis atramentaria (Ca), were studied for their antioxidant effect and their viability as functional food ingredients tested by incorporation into a food matrix (cottage cheese). In a first step, the individual extracts and a combination of both showing synergistic effects (Sl:Ca, 1:1) were microencapsulated by spray drying using maltodextrin as the encapsulating material [2]. After evaluating the antioxidant properties of the microencapsulated extracts and confirmation of their maintenance, comparatively to the corresponding free extract forms, the work proceeded with the incorporation of the microencapsulated and free forms into the cottage cheese. The incorporation of free extracts resulted in products with higher initial antioxidant activity (t=O days) but declining for t=7 days, which can be associated with their degradation. However, the cottage cheese enriched with the microencapsulated extracts, that have revelled a lower activity at initial time, showed for t=7 days an increase. This improvement can be explained by an effective protection provided by the microspheres together with a sustained release. Analyses performed on the studied cottage cheese samples showed the maintenance of the nutritional properties.

In this work, hydroalcoholic extracts of two mushrooms species, Suillus luteus (L.: Fries) (Sl) and Coprinopsis atramentaria (Bull.) (Ca), were studied for their synergistic antioxidant effect and their viability as functional food ingredients tested by incorporation into a food matrix (cottage cheese). In a first step, the individual extracts and a combination of both, showing synergistic effects (Sl:Ca, 1:1), were microencapsulated by spray-drying using maltodextrin as the encapsulating material. The incorporation of free extracts resulted in products with a higher initial antioxidant activity (t0) but declining after 7 days (t7), which was associated with their degradation. However, the cottage cheese enriched with the microencapsulated extracts, that have revealed a lower activity at the initial time, showed an increase at t7. This improvement can be explained by an effective protection provided by the microspheres together with a sustained release. Analyses performed on the studied cottage cheese samples showed the maintenance of the nutritional properties and no colour modifications were noticed.

A bioactive formulation based on the vegetative parts of the wild strawberry, Fragaria vesca L., was developed by using a microencapsulated extract (lyophilized infusion form). For that purpose, a process based on an atomization/coagulation technique with alginate as the wall material was applied. Among the tested hydromethanolic and aqueous extracts, both obtained from wild and commercial samples, the infusion of a wild species emerged as the most antioxidative one. The higher amounts of flavonols and flavan-3-ols found in the aqueous extracts seem to be responsible for this greater antioxidant activity. Furthermore, the developed bioactive formulation was applied in k-carrageenan gelatin, being observed that the antioxidant properties of the extract were preserved, as compared with the free form. Thus, the antioxidant activity of the Fragaria vesca L. vegetative parts was demonstrated, as well as the advantages of using microencapsulation to produce effective bioactive formulations.