Browsing by Author "Amaral, Renata A."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- Chemical-based methodologies approaches to extend the shelf life of fresh fish — a reviewPublication . Amaral, Renata A.; Pinto, Carlos A.; Lima, Vasco; Tavares, Jéssica; Martins, Ana P.; Fidalgo, Liliana G.; Silva, Ana M.; Gil, Maria M.; Teixeira, Paula; Barbosa, Joana; Barba, Francisco J.; Saraiva, Jorge A.Due to its characteristics, fresh fish is a highly perishable food with a very short shelf-life under refrigeration. Several methods have been introduced to slow down its deterioration, such as by means of oxygen depletion of the food package (vacuum packaging), or by changing the natural atmosphere that is in contact with the fresh fish (modified atmosphere packaging), or by the use of chemicals generally recognized as safe: such compounds can be directly applied (by dipping or spraying) or incorporated into packaging materials and slowly migrate to the product, exerting a hurdle effect against microbial development and lipid oxidation (active packaging). This review aims to cover the most recent advances in chemical-based approaches for fresh fish preservation, applied either singly or in combination. Vacuum packaging, modified atmosphere, and active packaging preservation methodologies are presented, along with the inclusion of chemical additives, such as organic acids and natural extracts, and their combination with icing systems. Advantages and disadvantages of these methodologies and their impact on fresh fish quality and shelf-life are discussed, reaching the conclusion that both are positively influenced overall. Indeed, the contribution of chemical-based strategies for fresh fish preservation is undeniable, and is expected to be a research topic of increasing interest in the future.
- Combining high pressure and electric fields towards nannochloropsis oculata eicosapentaenoic acid-rich extractsPublication . Sousa, Sérgio; Carvalho, Ana P.; Pinto, Carlos A.; Amaral, Renata A.; Saraiva, Jorge A.; Pereira, Ricardo N.; Vicente, António A.; Freitas, Ana C.; Gomes, Ana M.Nannochloropsis oculata is naturally rich in eicosapentaenoic acid (EPA). To turn this microalga into an economically viable source for commercial applications, extraction efficiency must be achieved. Pursuing this goal, emerging technologies such as high hydrostatic pressure (HHP) and moderate electric fields (MEF) were tested, aiming to increase EPA accessibility and subsequent extraction yields. The innovative approach used in this study combined these technologies and associated tailored, less hazardous different solvent mixtures (SM) with distinct polarity indexes. Although the classical Folch SM with chloroform: methanol (PI 4.4) provided the highest yield concerning total lipids (166.4 mglipid/gbiomass), diethyl ether: ethanol (PI 3.6) presented statistically higher values in terms of EPA per biomass, corresponding to 1.3-fold increase. When SM were used in HHP and MEF, neither technology independently improved EPA extraction yields, although the sequential combination of technologies did result in 62% increment in EPA extraction. Overall, the SM and extraction methodologies tested (HHP—200 MPa, 21 °C, 15 min, followed by MEF processing at 40 °C, 15 min) enabled increased EPA extraction yields from wet N. oculata biomass. These findings are of high relevance for the food and pharmaceutical industries, providing viable alternatives to the “classical” extraction methodologies and solvents, with increased yields and lower environmental impact.
- Effect of high-pressure processing to improve the safety and quality of an Quercus acorn beveragePublication . Sardão, Rita; Amaral, Renata A.; Alexandre, Elisabete M. C.; Saraiva, Jorge A.; Pintado, ManuelaThe development of an acorn beverage can be an opportunity to increase the intake of bioactive compounds and add value to Quercus acorn. However, unprocessed plant-based beverages have a very short shelf-life and thermal treatments affect their overall quality. High-pressure processing (HPP) emerges as a possible solution to better retain nutritional properties and sensorial quality and extend shelf-life. This research assessed the impact of HPP (450/600 MPa, 5/12.5/20 min) and thermal processing (TP, 85 °C, 30 min) on an acorn beverage during 63 days of refrigerated storage (4 °C). From all processing conditions, HPP at 450 MPa for 5 min showed to be suitable to assure microbiological safety (mesophiles, psychrophiles, yeasts and moulds, and Enterobacteriaceae) during 63 days and to better preserve total soluble solids and colour. The antioxidant activity (ABTS/DPPH) was similar to higher for heat-treated samples, being gallic acid the main phenolic compound found in the beverage. Total carbohydrates, lipids, proteins, minerals, and fatty acids contents were similar for HPP and TP. This beverage revealed low thrombogenicity and atherogenicity indices, and potassium as the main mineral. Concluding, HPP extended the shelf-life of the beverage and improved the physicochemical quality, revealed by panellists preference, as revealed by sensorial analysis.