Chemical Process Engineering and Forest Products Research Centre

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Publications

A review of conventional and emerging technologies for hydrogels sterilization

Publication . S. A. Bento, Cristiana; C. Gaspar, M.; Coimbra, Patrícia; de Sousa, Hermínio C.; E. M. Braga, Mara

Hydrogels are extensively used in the biomedical field, as drug delivery systems, wound dressings, contact lenses or as scaffolds for tissue engineering. Due to their polymeric nature and the presence of high amounts of water in their structure, hydrogels generally present high sensitivity to terminal sterilization. The establishment of an efficient sterilization protocol that does not compromise the functional properties of the hydrogels is one of the challenges faced by researchers when developing a hydrogel for a specific application. Yet, until very recently this aspect was largely ignored in the literature. The present paper reviews the state of literature concerning hydrogels sterilization, compiling the main findings. Conventional terminal sterilization methods (heat sterilization, radiation sterilization, and gas sterilization) as well as emerging sterilization techniques (ozone, supercritical carbon dioxide) are covered. Considerations about aseptic processing are also included. Additionally, and as a framework, hydrogels’ polymeric materials, types of networks, and main biomedical applications are summarily described.

2023-02-01Journal article

Open access

Supercritical fluid technology for agrifood materials processing

Publication . Braga, Mara E M; Gaspar, M. C.; de Sousa, Hermínio C

Supercritical fluid technology has been applied in the food area for processing and preserving food products and/or monitoring the food quality, with known advantages. The main solvent used at supercritical conditions for food applications is carbon dioxide. Some examples are presented, from the traditional decaffeination of coffee up to the micronization of vanilla, passing through innovative processes such as the extrusion of protein-based snacks and drying of beetroot. The gap between research and industries is addressed, mainly due to a lack of data about food chemical changes that may occur during some processes, as well as technical data. However, this is an area in clear expansion and probably, in the future, we will have a menu composed of meals prepared by supercritical methods.

2023-01-02Journal article

Open access

Edible films and coatings based on agrifood residues: A new trend in the food packaging research

Publication . Gaspar, Marisa C; Braga, Mara E M

Food packaging trends have been changing in the last years, mainly due to consumer concerns about plastic pollution and agrifood waste. Recent advances in the development of edible films and coatings are discussed. These systems can be much more than packaging, with additional functions such as antioxidant, antimicrobial, and nutritional properties, among others. Challenges in industrial processes and/or in some films’ properties are addressed from the authors’ point of view. The use of agrifood residues in these packaging systems is included as a promising strategy that promotes sustainability and circular economy. The authors consider that more research and actions are needed to achieve the best packaging material for each food product with reduced production costs.

2023Journal article

Open access

Edible films produced from agrifood by-products and wastes

Publication . Jorge, Alexandre M.S.; Gaspar, Marisa C.; Henriques, Marta H.F.; Braga, Mara E.M.

This study aims to develop edible films using agrifood by-products (pumpkin seeds, broken rice and orange pectin) and wastes (quince peel, potato peel, potato pulp, orange peel, pumpkin peel). The physicochemical characteristics of the films were investigated, including their mechanical and barrier properties. Higher amounts of plasticizer induced poorer mechanical and barrier properties in the films. The most promising ones were obtained with orange pectin, broken rice and pumpkin peel, with water contact angles (WCA) between 48° and 57°, maximum water vapor transmission rate and water vapor permeability of 575 g.m−2.d−1 and 108 × 10−12 g.Pa−1.s−1.m−1, respectively, Young's modulus between 350 and 800 MPa, maximum tensile strength between 9.0 and 26.25 MPa, and elongation at break between 2.28 and 9.3%. Orange pectin and broken rice are promising raw materials since they led to higher WCA, better barrier and mechanical properties. Broken rice and quince peel can be good substitutes for commercial starch and glycerol, respectively. Agro-industrial by-products and wastes revealed potential for the production of sustainable edible films.

2023-07-26Journal article

Open access

Sustainable starch-based edible films with agrifood residues as potential carriers for the probiotic Lactobacillus rhamnosus

Publication . Coimbra, Patrícia; Alarico, Susana; Empadinhas, Nuno; Braga, Mara E.M.; Gaspar, Marisa C.

Edible films are promising carriers for probiotics and can be composed by agrifood residues, which are usually rich in polymers and bioactive compounds. In this work, starch-based films were enriched with three types of agrifood residues (quince, potato and orange peels) and the incorporation of the probiotic Lactobacillus rhamnosus was studied, as well as the addition of inulin as a protective prebiotic. The resulting films were characterized in terms of mechanical properties, physicochemical properties, lactobacilli viability and microbiological properties. The mechanical properties of the films generally decreased with the introduction of L. rhamnosus, although this was highly dependent on the film composition. All films exhibited water vapor permeabilities in the typical range of starch-based films and were not greatly affected by the inclusion of probiotics. The loss of probiotic viability during films production was strongly related to the pH of the film-forming solutions. Films with agrifood residues had a slower loss of probiotic viability during storage, when compared to plain starch films, which may be explained by the presence of antioxidant compounds. Inulin was expected to improve viability, but this was not observed. Microbiological analysis showed that agrifood residues powders contained natural contaminant bacteria that were partially eliminated during film formation. Moreover, none of the target foodborne pathogens were detected in the analyzed samples. Overall, the results suggest that edible films containing agrifood residues can be a promising material for the delivery of probiotics and/or as primary packaging for some food products.

2023-08-11Journal article

Open access