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- Upcycling fish by-products into bioactive fish oil: the suitability of microwave-assisted extractionPublication . Pinela, José; Rodrigues, Matilde; Pires, Tânia C.S.P.; Mandim, Filipa; Almeida, André; Dias, Maria Inês; Caleja, Cristina; Barros, LillianThe seafood industry is often left out of the food waste discussion, but this sector is no exception, as it generates large amounts of various by-products. This study aimed to explore the potential of the microwave-assisted extraction (MAE) technique to obtain high-quality oil from fish by-products. The independent variables, which were time (1-30 min), microwave power (50-1000 W), and solid/liquid ratio (70-120 g/L) were combined in a 20-run experimental design coupled with the response surface methodology (RSM) for process optimization. The obtained oil yield values were fitted to a quadratic equation to build the theoretical models, which were statistically validated based on statistical criteria and used to predict the optimal MAE condition. The oil yields were significantly affected by the three independent variables through linear, quadratic, and/or interactive effects. Compared to a conventional Soxhlet extraction (SE), the optimal MAE conditions allowed between 60 and 100% of oil to be recovered in less than 19 min and with less solvent consumption. The fatty acid profiles of the oils obtained through SE and optimized MAE were characterized by gas chromatography with flame ionizing detection (GC-FID) after a derivatization process. These oils were constituted mainly of health, beneficial unsaturated fatty acids, such as oleic, docosahexaenoic (DHA), linoleic, and eicosapentaenoic (EPA) acids, which were not affected (p > 0.05) by the extraction methods. Interestingly, the oils obtained through MAE showed the best microbial growth inhibition results may have been due to thermolabile compounds, preserved via this unconventional non-thermal method. The oils also exhibited anti-inflammatory effects via nitric oxide production inhibition and cytotoxic potential especially, against breast and gastric adenocarcinoma cells. However, the threshold of toxicity should be further investigated. Overall, this work emerges as a future-oriented approach to upcycling fish by-products into high-quality oils that can be used in the formulation of pet food and other products.
- Natural food ingredients from quince peel: towards a "zero-waste" production systemPublication . Pereira, Alexis; Añibarro-Ortega, Mikel; Rodrigues, Matilde; Nogueira, António José M.; Pinela, José; Barros, LillianQuince is the yellow fruit of the deciduous tree Cydonia oblonga Mill. Its taste is sour and astringent when eaten raw, so it is usually processed into marmalade and many other food products, mostly sweets, through processes that discard the peel as a by-product. Therefore, this work was carried out to promote the upcycling of quince peel into valuable food ingredients following a "zero waste" approach. A response surface methodology (RSM)-coupled experimental design with 20 runs, combining five levels of time (1–120 min), temperature (25–95 °C) and ethanol concentration (0–100%), was implemented for maximizing the extraction of soluble solids and malic acid while simultaneously obtaining fiber concentrate extracts. The yields of soluble solids and fiber concentrate extracts were determined gravimetrically. Malic acid, which has been used as a food preservative, was analyzed by ultra-fast liquid chromatography with photodiode array detection.1 The dietary fiber content of the fiber concentrate extracts was determined by an enzymatic-gravimetric method (AOAC Official Method 985.29) and their color was measured with a portable colorimeter.2,3 The three independent variables affected significantly the extraction process and the predictive model equations were validated based on different statistical criteria, which allowed to determine the optimal extraction conditions. In general, the soluble solids yield was promoted by lower temperatures and ethanol concentrations, while malic acid was better extracted at higher temperatures for longer processing times. In turn, the fiber concentrate extracts remaining after extraction had opposite yields to the soluble solids. However, the highest yields of these fiber concentrates were not in agreement with their dietary fiber contents. The highest fiber values were recorded in the concentrate extracts obtained at high temperatures and medium-low ethanol concentrations. In fact, only these two independent variables significantly impacted its extraction, through linear, quadratic, and also interactive effects. Furthermore, the lighter fiber concentrate extracts were those with the highest yields. Overall, quince peel can be totally upcycled into natural food ingredients rich in malic acid and dietary fiber.
- Nutritional and bioactive traits of Kweli® red raspberry cultivated in PortugalPublication . Rodrigues, Matilde; Vara, Ana Luísa; Petrović, Jovana; Dias, Maria Inês; Nogueira, António José M.; Soković, Marina; Ferreira, Isabel C.F.R.; Pinela, José; Barros, LillianRed raspberry (Rubus idaeus L.) is an increasingly popular food in contemporary diets due to its freshness, organoleptic features, nutritional value, and health claims. From the nutritional point of view, red raspberry has been described as containing vitamins, minerals, soluble fiber, reducing sugars, citric acid, and phenolic compounds.1 Anthocyanins are of particular interest in this fruit, since these pigments provide the characteristic red-purple color, as well as bioactive properties.1,2 The demand for raspberries has risen sharply in Europe and North America and, among the existing cultivars, Kweli® is one of the most productive and suitable for growing in moderate and Mediterranean climates. High levels of ellagitannins, anthocyanins, and vitamin C have been described in this cultivar and its phytochemical content has been correlated with antioxidant properties.1,2 Still, little else is known about the nutritional composition of Kweli®. Therefore, this work was performed to characterize the nutritional and chemical composition of this red raspberry cultivar gown in northern Portugal and assess its in vitro antioxidant and antimicrobial activities. Fresh fruits at commercial maturity were harvested and immediately lyophilized. Its proximate composition was determined by official method of food analysis and the concentrations of free sugars, organic acids, tocopherols, and fatty acids were evaluated by different chromatographic techniques.3 Anthocyanins were identified in an hydroethanolic extract prepared by solid-liquid extraction, which was also used to evaluate bioactive properties.3 The antioxidant activity was evaluated via inhibition of β-carotene bleaching, formation of thiobarbituric acid reactive substances (TBARS), and oxidative hemolysis.3 The antimicrobial activity was tested against foodborne bacterial and fungal strains by microdilution methods.3 Moisture (approximately 83%) and carbohydrates (16.12%), of which fructose (2.42%) and glucose (2.13%), were major constituents of Kweli® red raspberry, followed by ash (0.66%) and protein (0.18%). The fat content was quite low and consisted mainly by unsaturated fatty acids (58%), with a prevalence of oleic acid. High levels of citric (2.7%) and ascorbic (17 mg/100 g) acids and tocopherols (1.92 mg/100 g) were also detected. The anthocyanins (4.51 mg/g extract) cyanidin-O-hexoside and mostly cyanidin-O-sophoroside were identified in the hydroethanolic extract, which was able to inhibit in some extent the formation of TBARS, oxidative hemolysis, and β-carotene bleaching. In turn, the extract was more effective than the food additive E224 against Bacillus cereus. Overall, these results highlighted the nutritional quality of Kweli® red raspberry and may be useful to complete food composition databases. Therefore, the inclusion of this berry in a daily diet can be helpful to obtain nutrients and antioxidants and bring health benefits.
- Propiedades nutricionales y bioactivas de la frambuesa roja Kweli® cultivada en PortugalPublication . Rodrigues, Matilde; Vara, Ana Luísa; Petrović, Jovana; Dias, Maria Inês; Soković, Marina; Nogueira, António José M.; Ferreira, Isabel C.F.R.; Pinela, José; Barros, LillianLa frambuesa roja (Rubus idaeus L.) es un alimento cada vez más popular en la dieta contemporánea debido a su frescura, características organolépticas y evidencias de propiedades saludables. Desde el punto de vista composicional, la frambuesa roja contiene vitaminas, minerales, fibra soluble, azúcares reductores, ácido cítrico y compuestos fenólicos [1]. Las antocianinas son de especial interés en esta fruta, ya que estos pigmentos le proporcionan el característico color rojo-púrpura y propiedades bioactivas [1,2]. La demanda de frambuesas ha aumentado considerablemente en Europa y América del Norte y, entre los cultivares existentes, Kweli® es uno de los más productivos y aptos para el cultivo en climas moderados y mediterráneos. Sobre este cultivar ya se han descrito altos niveles de elagitaninos, antocianinas y vitamina C y su contenido fenólico se ha correlacionado con propiedades antioxidantes [1,2]. Sin embargo, poco más se sabe sobre la composición nutricional de Kweli®. Por lo tanto, este trabajo se realizó para caracterizar la composición nutricional y química de este cultivar de frambuesa roja y evaluar su actividad antioxidante y antimicrobiana. Los frutos frescos en su madurez comercial fueron cosechados e inmediatamente liofilizados. Se determinó su composición proximal por los métodos oficiales de análisis de alimentos y se evaluaron las concentraciones de azúcares libres, ácidos orgánicos, tocoferoles y ácidos grasos mediante diferentes técnicas cromatográficas [3]. Se identificaron las antocianinas en un extracto hidroetanólico preparado por extracción sólido-líquido, que también se utilizó para evaluar las propiedades bioactivas [3]. La actividad antioxidante se evaluó mediante la inhibición del blanqueo del β-caroteno, de la formación de sustancias reactivas al ácido tiobarbitúrico (TBARS) y de la hemólisis oxidativa [3]. La actividad antimicrobiana se probó contra cepas bacterianas y fúngicas transmitidas por los alimentos mediante métodos de microdilución [3]. La humedad (~83%) y los hidratos de carbono (16,12%), de los cuales la fructosa (2,42%) y la glucosa (2,13%), fueron los principales componentes de la frambuesa roja, seguidos de las cenizas (0,66%) y las proteínas (0,18%). El contenido en grasa era bastante bajo y estaba compuesto principalmente por ácidos grasos insaturados (58%), con predominio del ácido oleico. También se detectaron niveles elevados de ácidos cítrico y ascórbico y tocoferoles. Las antocianinas cianidina-3-O-glucósido y cianidina-3-O-soforósido se identificaron en el extracto, que fue capaz de inhibir en cierta medida la formación de TBARS, la hemólisis oxidativa y el blanqueo del β-caroteno. Además, el extracto fue más eficaz que el aditivo alimentario E224 contra Bacillus cereus. Estos resultados destacan la calidad nutricional de la frambuesa roja y pueden ser útiles para completar las bases de datos de composición de alimentos. Por lo tanto, la inclusión de esta baya en la dieta diaria puede ser útil para obtener nutrientes y antioxidantes y aportar beneficios para la salud.
- Omega-3 fatty acids from fish by-products: Innovative extraction and application in food and feedPublication . Rodrigues, Matilde; Rosa, Ana; Almeida, André; Martins, Rui; Ribeiro, Tânia; Pintado, Manuela; Gonçalves, Raquel F.S.; Pinheiro, Ana C.; Fonseca, António J.M.; Maia, Margarida R.G.; Cabrita, Ana R.J.; Barros, Lillian; Caleja, CristinaOmega -3 fatty acids (O3FA) are essential nutrients that play a crucial role in maintaining human and animal health. They are known for their numerous health claims, including cardiovascular benefits, contributing to both the prevention and treatment of immunological, neurological, reproductive, and cardiovascular complications, and supporting overall well-being. Fish, especially oily fish, comprise rich source of O3FA. In the fish industry, significant amounts of by-products and waste are generated during processing which are often discarded or used for lower -value applications. However, there is recognition of the potential value of extracting O3FA from these by-products. Various extraction techniques can be used, but the goal is to efficiently extract and concentrate the O3FA while minimizing the loss of nutritional value. To prevent oxidation and maintain the stability of O3FA, natural antioxidants can be added. Antioxidants like polyphenolic compounds and plant extracts help to protect the O3FA from degradation caused by exposure to oxygen, light, and heat. By stabilizing the O3FA, the shelf life and nutritional value of the extracted product can be extended. In summary, this work presents a forwardlooking strategy for transforming fish by-products into high -quality oils, which hold great potential for application in food and feed.
- Perfil fenólico, atividade antioxidante e teor de fibra da casca de marmeloPublication . Pereira, Alexis; Añibarro-Ortega, Mikel; Dias, Maria Inês; Othman, Souha; Rodrigues, Matilde; Ferreira, Isabel C.F.R.; Pinela, José; Barros, LillianO marmelo tem sido objeto de vários estudos científicos focados na caracterização da sua composição nutricional e fitoquímica e na avaliação de proprieddaes biológicas, sobretudo da polpa e das sementes.