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- Novas tecnologias de processamentoPublication . Silva, Cristina L. M.; Alexandre, Elisabete M. C.; Santos, Dora M.; Vieira, Margarida C.; Gonçalves, Elsa M.; Oliveira, António J.
- Impact of non-thermal technologies and sanitizer solutions on microbial load reduction and quality factor retention of frozen red bell peppersPublication . Alexandre, Elisabete M. C.; Brandão, Teresa R. S.; Silva, Cristina L. M.The effect of non-thermal technologies (ozone in aqueous solution, ultrasounds and ultraviolet C radiation) and washings with chemical solutions (sodium hypochlorite and hydrogen peroxide) on Listeria innocua survival was studied in red bell peppers. Quality attributes such as total colour difference, firmness, pH and ascorbic and dehydroascorbic acid content were also evaluated. The treatments were applied before product storage under frozen conditions (-7 and -30 degrees C). Pre-washings with hydrogen peroxide solutions allowed obtaining frozen shred red bell peppers with lower microbial loads, when compared to the results obtained with the remaining treatments. However, those washings had a negative impact on colour and firmness. Alternatively, ozonation provided microbial reductions significantly higher than water-washings and improved, or at least allowed to preserve, all quality parameters analysed under both storage conditions. Storage at -7 degrees C provided higher microbial reductions in red bell peppers. However, this temperature implied higher colour alterations and ascorbic acid losses. Industrial relevance: The native microbial flora of fresh fruits and vegetables may include pathogens which are dangerous threats to consumers. Thermal treatments are conventionally used to attain safety standards; however, overall quality may be negatively affected by heat. Chemical treatments (environmental friendly) or non-thermal processes such as ozone, UV-C radiation and ultrasonication are promising technologies. From an industrial point of view, these processes may have potential application if safe and high quality produce is to be attained.
- Non-thermal treatments impact on safety and quality aspects of refrigerated strawberry (Fragaria anannassa)Publication . Alexandre, Elisabete M. C.; Santos, Dora M.; Brandão, Teresa R. S.; Silva, Cristina L. M.
- Effect of modified atmosphere on phytochemical profile of pasteurized peach puréesPublication . Oliveira, Ana; Coelho, Marta; Alexandre, Elisabete; Gomes, Maria Helena; Almeida, Domingos P. F.; Pintado, ManuelaPeach phytochemical profile was analysed during 90 days storage under three different gas mixtures: 10 kPa O2+90 kPa N2, 100 kPa N2 and air (78 kPa N2+21 kPa O2+0.03 kPa CO2) for both 4 and 23 °C. The antioxidant activity increased when peach purée was stored under air at 4 °C and 100 kPa N2 at 23 °C, while total phenolic content was not affected by atmospheres. Total carotenoids were more stable for 100 kPa N2, where it decreases 48 and 58% respectively for 4 and 23 °C. The content of (+)-catechin decreased 42% for 10 kPa O2 at 4°C, remaining constant in other atmospheres. Chlorogenic and neochlorogenic acids were well preserved in atmospheres containing oxygen, presenting an increase of 14 and 24% for 10 kPa O2 at 4°C. The higher content of carotenoids was obtained for 100 kPa N2 at 23 °C. Principal component analysis shows that atmospheres variance was associated with carotenoids while storage time was more related with total phenolics and total antioxidant capacity.
- Environmental footprint of emerging technologies, regulatory and legislative issuesPublication . Castro, Sónia M.; Inácio, Rita S.; Alexandre, Elisabete M. C.; Fidalgo, Liliana G.; Pereira, Sofia; Quaresma, Patrícia; Freitas, Paulo; Teixeira, Paula; Pintado, Maria Manuela; Gomes, Ana M.; Tonello, Carole; Saraiva, Jorge A.Consumers are more demanding, better educated in terms of food quality and nutritional aspects, and forcing producers along with regulatory agencies to search for alternative processing technologies. Some of these technologies like high pressure, pulsed electrical fields, supercritical CO2, ultrasound, ozone, or plasma treatment are at industrially use, pilot scale, or even at the edge of application, but the most successful ones at the moment, with already a wide variety of commercial products, are high hydrostatic pressure and pulsed electrical fields. These technologies offer better products, both “natural” in terms of fresh-like flavor and ingredients and safe with extended shelf-life. This tendency leads to the need for a global regulation system that ensures quality of food regardless of country of origin and, at the same time, without compromising safety. In addition to this system, there should be governing bodies that regulate and monitor the enforcement of these food-processing regulations, to avoid regulations that often only apply to countries belonging to specific organizations. Together with food legislation concerns, sustainable food manufacturing and related efficient energy use have also became priorities of the food industries. While conventional preservation processes (e.g., canning, freezing, drying) mainly use thermal energy, more complex processes use mechanical, electromagnetic, electrical, and other forms of energy, which can reduce the energy consumption. Indeed the efficient use of resources in food industry is a critical element for the future generations for sustainable food processing, but the impact of energy requirements in emerging technologies has not been a matter of intense discussion. The objective of this chapter is to provide a concise overview of environmental footprint of emerging technologies, namely high-pressure processing and pulsed electric fields, and their current related food legislation status in various countries.
- Long-term frozen storage and pasteurization effects on strawberry polyphenols contentPublication . Oliveira, Ana; Coelho, Marta; Alexandre, Elisabete M. C.; Almeida, Domingos P. F.; Pintado, ManuelaThe profile of the strawberry polyphenols was analysed on fresh strawberry, immediately after freezing or after pasteurization and during frozen storage of strawberry at -20 A degrees C for 360 days. Freezing increased the extractability of (-)-epigallocatechin gallate (60 %), (-)-epicatechin (48 %) and ellagic acid (51 %) and decreased the pelargonidin-3-glucoside (18 %). Direct pasteurization of fresh strawberry increased the extractability for (-)-epigallocatechin gallate (73 %), (-)-epicatechin (45 %) and ellagic acid (143 %) and decreased for pelargonidin-3-glucoside (16 %). During storage at -20 A degrees C for 360 days the extractable levels of pelargonidin-3-rutinoside, (-)-epigallocatechin gallate, (+)-catechin, (-)-epicatechin and ellagic acid decreased by 17, 20, 37, 65 and 80 %, respectively, while those of pelargonidin-3-glucoside increased 13 %. Changes in polyphenols content, produced by pasteurization after 360 days frozen storage, were minimal. Polyphenols content decreased during storage of strawberry pieces at -20 A degrees C for 360 days, while the thermal treatment applied after freezing storage did not induce any significant change.
- High value-added compounds from fruit and vegetable by-products – characterization, bioactivities, and application in the development of novel food productsPublication . Trigo, João P.; Alexandre, Elisabete M. C.; Saraiva, Jorge A.; Pintado, Manuela E.Fruit and vegetable processing industry is one of the relevant generators of food by-products, which display limited commercial exploitation entailing economic and environmental problems. However, these by-products present a considerable amount of dietary fiber as well as bioactive compounds with important biological activities such as antioxidant and antimicrobial properties. Therefore, the international scientific community has considered the incorporation of their extracts or powders to preserve or fortify food products an area of interest, mainly because nowadays consumers demand the production of safer and health-promoting foods. In the present review, several statistical and other relevant data concerning the increasing generation of fruit and vegetable by-products (FVB) are critically analyzed and presented. Next, a special focus is given to the chemical characterization and bioactivities (namely antioxidant and antimicrobial properties) of several FVB. Lastly, an in-depth review with recent studies (briefly compiled) about the incorporation of fruit and vegetable processing wastes in animal, dairy, beverages, and bakery products, among others is provided.
- Modelling microbial load reduction in foods due to ozone impactPublication . Alexandre, Elisabete M. C.; Brandão, Teresa R. S.; Silva, Cristina L. M.
- Effect of non-thermal methods on the safety of strawberries (Fragaria anannassa) and watercress (Nasturtium officinale)Publication . Alexandre, Elisabete M. C.; Santos, Dora M.; Fundo, Joana; Brandão, Teresa R. S.; Silva, Cristina L. M.
- Assessment of the impact of hydrogen peroxide soutions on microbial loads and quality factors of red bell peppers, strawberries and watercressPublication . Alexandre, Elisabete M.C.; Brandão, Teresa R.S.; Silva, Cristina L.M.The impact of sodium hypochlorite and hydrogen peroxide (H2O2 at 1 and 5%) solutions on Listeria innocua in red bell peppers, total mesophiles in strawberries and total coliforms in watercress was studied. Quality attributes such as colour, firmness and pH were studied for all products; total anthocyanins content was determined for strawberries. Sensorial analyses were also carried out for all products. Results showed that H2O2 (5%) provided the highest reductions of microbial loads. Besides H2O2 (1%) had a lower impact, it was more effective than water-washings. Sodium hypochlorite solutions lead to microbial reductions comparable to water risings. In terms of quality, H2O2 (5%) was the solution with higher negative impact on products’ colour. For strawberries, such colour alterations were also detected by sensorial analyses. The anthocyanins content decreased significantly. Overall it was found that H2O2 (1%) was a good sanitizer solution, since microbial reduction was attained while quality factors did not suffer considerable alterations.