Browsing by Author "Guerra, Manuela"
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- Effect of Rocha pear peel extracts added to wheat and rye bread formulations on acrylamide reduction and sensory quality maintenancePublication . Morgado, Cátia; Bernardo, Patrícia; Henriques, Inês; Jesus, Susana; Rego, Andreia; Delgado, Inês; Coelho, Inês; Castanheira, Isabel; Félix, Nelson; Fernandes, António; Guerra, Manuela; Brandão, CarlosPear peels are seen as potentially valuable for their low-cost beneficial components content such as polyphenols. These may reveal acrylamide (AA) mitigation effect and thus their application in a susceptible food matrix, such as bread, should be considered. Aiming to assess the AA reduction potential of Rocha pear peels in bread and the effects on its sensory quality, two types of bread highly consumed in Portugal - wheat (WB) and rye (RB) – were assayed with the extract of these by-products, in two forms aqueous [a] and dry [d]. Eight bread batches were produced (4 WB; 4 RB); each composed of one control sample and five replicates added with extract. The process included controlled fermentation, and cooking in a traditional oven (TO) and convection oven (CO). Hedonic evaluation was made to samples of each batch. Overall, slight differences were observed for WB and RB hedonic evaluation between the control sample and those with both extract forms. Lower scores were observed in both bread types baked in CO, with [d] comparing with the control; for bread with [a], oven influence varied; higher scores for WB in CO and for RB baked in TO, comparing with the control. Regarding AA reduction, the highest mitigation rate was accomplished by the [d] in WB cooked in a CO, 27.3%. However, for RB the best formulation was obtained with [d] in the TO, 19.2%. These results support the importance of selecting the best baking process according to the varieties of bread and AA reduction.
- Evaluation of the oxidative status of salami packaged with an active whey protein filmPublication . Andrade, Mariana A.; Ribeiro-Santos, Regiane; Guerra, Manuela; Sanches-Silva, AnaActive packaging aims to prolong food's shelf-life by directly interacting with the packaged food. This type of packaging is characterized by having the active agent incorporated into the package polymer, such as antioxidant additives, that will gradually migrate from the package polymer to the packed food and, consequently, delay food's natural lipid oxidation. In this study, the efficiency of an active whey protein film incorporated with a rosemary extract on retarding the lipid oxidation of salami slices was evaluated. The lipid oxidation of the salami was measured by the thiobarbituric acid reactive substances (TBARS) assay and hexanal monitorization. Also, a sensory analysis on the salami packaged for 60 and 90 days was performed. The active film was able to delay the salami's lipid oxidation for, at least, 30 days. The samples packaged with the active film revealed a bitter taste related to the rosemary extract and a bit sweet from the WP and the glycerol.
- Mitigation of acrylamide in bread by plant extracts and by productsPublication . Jesus, Susana; Delgado, Inês; Rego, Andreia; Bordado, João; Lopes, Rui; Brandão, Carlos; Guerra, Manuela; Morgado, Cátia; Coelho, Inês; Castanheira, IsabelAcrylamide (AA) is a carcinogen, mutagen and reproductive toxicant, mainly formed by the reaction between an amino acid, asparagine and a reducing sugar. The compound is formed in cereal, coffee and potato based products. In 2017 the European Commission established a regulation for AA levels in foodstuffs and AA mitigation measures. Recently, many studies demonstrated a positive correlation between AA mitigation and the application of herbs extracts, spices and antioxidants in bread. However, due to the complexity of the Maillard Reaction, the mitigation mechanism is still unknown. To study the impact of plant extracts (fennel, oregano, lemon balm), by products extracts (Rocha pear peel) and baking process (traditional oven vs convection oven) in the formation of acrylamide in three types of breads (wheat, rye and sweet yeast). The highest AA mitigation occurred in wheat bread with addition of fennel dry extract, followed by the fennel dry extract (etanol) in rye bread. No AA mitigation was verified in sweet yeast bread, likely due to the higher concentration of sugar in this type of bread. The impact of the baking process in AA formation was inconclusive. AA mitigation can be related with the phenolic profile and the interactions between bioactive compounds.