Daniela Freitas

Mrs. Daniela Freitas

orcid

Research Focus & Metrics

Academic Career Length

2Years (2025-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
5 September 2025 in Sci
Verified
Journal Article
Open access
PDF file
DFDaniela Freitas
Daniela Freitas
Ana Rita CoelhoAna Rita Coelho
Ana Rita Coelho
JDJoão Dias
João Dias
MFMiguel Floro
Miguel Floro
Ana Coelho MarquesAna Coelho Marques
Ana Coelho Marques
OAOlga Maria Amaral
Olga Maria Amaral
Grape pomace (i.e., the residual skins, seeds, and pulp left after vinification) retains up to 70% of the fruit’s original phenolic compounds and is also rich in dietary fiber. As such, because this by-product is generated in large quantities worldwide and its disposal is both technologically problematic and costly, reusing it as a food ingredient could simultaneously mitigate environmental burdens, lower winery waste-management expenses, and enhance the nutritional profile of fortified foods. In this context, this study investigated the nutritional enrichment of dark chocolate by incorporating flour produced from red (cv. Syrah) and white (cv. Arinto) grape pomace at three levels (5, 10, and 15% w/w). Formulated chocolates and controls were manufactured under industrial tempering conditions and subsequently analyzed for protein, lipids, sugars, dietary fiber, total phenolic content, antioxidant capacity (DPPH and ORAC), color, texture, and consumer perception (hedonic test). All fortified samples showed higher fiber and antioxidant activity than the control, with “White_15” showing higher fiber content (43.1%) and “Red_5” for ORAC (69,483 µmol TE/100 g) and DPPH (6587 µmol TE/100 g). Dietary fiber showed an increase in content with the increase in grape pomace incorporation, regardless of the type (red or white). Texture softening was observed in all fortified chocolates independently of the incorporation level or type (red or white). Principal Component Analysis (PCA) and hierarchical clustering confirmed clear separation between control and fortified chocolates based on the parameters analyzed. Sensory evaluation with untrained panelists revealed good overall acceptability across all formulations. These findings demonstrate that grape pomace flour can be effectively valorized as a functional ingredient in dark chocolates, supporting circular economy practices in the wine and confectionery sectors while delivering products with enhanced health-promoting attributes (nutritional and antioxidant).

30 October 2025 in Dairy
Verified
Journal Article
Open access
PDF file
JSJoão Miguel Santos
João Miguel Santos
JGJoão Nuno Pinto Miranda Garcia
João Nuno Pinto Miranda Garcia
JDJoão Dias
João Dias
JMJoao Martins
Joao Martins
Nuno Bartolomeu AlvarengaNuno Bartolomeu Alvarenga
Nuno Bartolomeu Alvarenga
JCJosé Jasnau Caeiro
José Jasnau Caeiro
Improving the energy efficiency of traditional production methods while preserving their cultural and economic value is a challenge aligned with the Sustainable Development Goals of the 2030 agenda. Refrigeration during cheese maturation is particularly energy-intensive, contributing significantly to greenhouse gas emissions and operating costs. An approach to make traditional cheese production more sustainable, through the development of a prototype ripening chamber with a natural refrigerant-based refrigeration system powered by renewable energy was studied. A dedicated system based on an Internet of Things architecture was developed using low-cost sensors, microcontroller units, and single-board computers to enable real-time measurement and monitoring of environmental variables and energy consumption throughout the ripening process. A comparative analysis was conducted using ewe’s milk cheese, produced and ripened with Protected Designation of Origin conditions, in both the prototype and the conventional chambers over four weeks, quantifying energy consumption and evaluating product quality. Results demonstrate the technical feasibility of energy efficient and sustainable refrigeration systems, as well as the possibility of retrofitting installed cheese ripening chambers with affordable IoT monitoring systems, while maintaining traditional cheese quality standards.

20 July 2025 in Applied Sciences
Verified
Journal Article
Open access
PDF file
Karina Santos Santos SilvérioKarina Santos Santos Silvério
Karina Santos Santos Silvério
DFDaniela Freitas
Daniela Freitas
JDJoão Dias
João Dias
Cheese production is an ancient practice that is associated with the food and cultural identity of different peoples. There are over 500 cheese types globally, including 207 with protected denomination of origin (PDO) and 70 with protected geographical indication (PGI) status in the European Union (EU). Each cheese has various biochemical compositions, production methods, and maturation environments. This study has provided a critical review of the environmental impacts of cheese production, focusing on energy consumption, greenhouse gas (GHG) emissions, and the integration of renewable energy sources as sustainable strategies for this sector. Based on case studies and life cycle assessment (LCA) methodologies, the analysis revealed significant variability in energy use (3.0 to 70.2 MJ/kg) and GHG emissions (up to 22.13 kg CO2 eq/kg), influenced by factors such as the cheese type, production complexity, system boundaries, and the technological or geographical context. Particular attention was given to heat treatment, refrigeration, and maturation processes, which contribute substantially to the overall energy footprint. The paper also discusses the methodological challenges in LCA studies, including the role of co-product allocation and database limitations. Finally, strategic renewable energy options, such as biogas recovery and solar thermal integration, are discussed as sustainable alternatives to reduce the environmental footprint of the dairy sector and support its sustainability.

8 September 2025 in Applied Sciences
Verified
Journal Article
Open access
PDF file
JDJoão Dias
João Dias
SGSandra Gomes
Sandra Gomes
Karina Santos Santos SilvérioKarina Santos Santos Silvério
Karina Santos Santos Silvério
DFDaniela Freitas
Daniela Freitas
Jaime Filipe FernandesJaime Filipe Fernandes
Jaime Filipe Fernandes
Nuno Bartolomeu AlvarengaNuno Bartolomeu Alvarenga
Nuno Bartolomeu Alvarenga
The enzymatic coagulation of milk, crucial in cheese production, entails the hydrolysis of κ-casein and subsequent micelle aggregation. Conventional assessment standards, such as the Berridge method, depend on visual inspection and are susceptible to operator bias. Recent methods for the identification of milk-clotting time rely on optical, ultrasonic, and image-based technologies. In the present work, the composition of milk was evaluated through standard methods from ISO and AOAC. Milk coagulation time (MCT) was measured through viscosimetry, Berridge’s operator-driven technique, and a machine learning approach employing computer vision. Coagulation was additionally observed using the Optigraph, which measures micellar aggregation through near-infrared light attenuation for immediate analysis. Sheep milk samples were analysed for their composition and coagulation characteristics. Coagulation times, assessed via Berridge (BOB), demonstrated high correlation (R2 = 0.9888) with viscosimetry (Visc) and machine learning (ML). Increased levels of protein and casein were linked to extended MCT, whereas lower pH levels sped up coagulation. The calcium content did not have a notable impact. Optigraph assessments validated variations in firmness and aggregation rate. Principal Component Analysis (PCA) identified significant correlations between total solids, casein, and MCT techniques. Estimates from ML-based MCT closely align with those from operator-based methods, confirming its dependability. This research emphasises ML as a powerful, automated method for evaluating milk coagulation, presenting a compelling substitute for conventional approaches.

9 January 2026 in Sci
Verified
Journal Article
Open access
PDF file
DFDaniela Freitas
Daniela Freitas
Ana Rita CoelhoAna Rita Coelho
Ana Rita Coelho
Ana Coelho MarquesAna Coelho Marques
Ana Coelho Marques
JDJoão Dias
João Dias
OAOlga Maria Amaral
Olga Maria Amaral
MSManuela Simões
Manuela Simões
The winemaking industry represents one of the most important sectors of the Mediterranean agrifood economy, generating large amounts of solid residues, especially grape pomace. The study aimed to evaluate during two consecutive harvest years the influence of the production system (conventional vs. organic) and cultivar on the mineral, chemical, and antioxidant composition, as well as the colorimetric properties, of grape pomaces obtained from four Vitis vinifera L. cultivars in Alentejo-Portugal. The results showed that mineral composition was significantly affected by both production system and cultivar, with organic grape pomace showing higher K and Mn contents, whereas Ca and Cu showed consistently higher content under conventional. Protein content tended to increase under organic production, while fiber and fat were overall higher in conventional, particularly in the first year. Sugars displayed strong cultivar specificity, with Arinto showing the highest concentrations (30 to 40%), and considering all cultivars, total phenolic content ranged between 4000 ando 9000 mg GAE/100 g, while antioxidant capacity varied among cultivars and years. Colorimetric parameters were essentially influenced by cultivar and harvest year rather than production system. The PCA revealed that PC1 (44.06%) represented a gradient associated with mineral and antioxidant composition, while PC2 (21.26%) reflected minor variation in color and sugars, and the hierarchical clustering distinguished Syrah and Alicante Bouschet as the cultivars most responsive to production system, whereas Aragonez and Arinto exhibited greater compositional stability across years. Overall, the findings indicate that both cultivar and management practices (organic and conventional) influence the compositional profile of grape pomace, with organic showing a tendency to enhance K, Mn, protein, and antioxidant parameters, whereas conventional practices favored higher levels of Ca, Cu, and fiber. The results provide valuable insights for the valorization of grape pomace and the development of sustainable viticultural strategies in Mediterranean environments.

30 October 2026 in Frontiers in Sustainable Food Systems
Verified
Journal Article
Open access
PDF file
DFDaniela Freitas
Daniela Freitas
Ana Rita CoelhoAna Rita Coelho
Ana Rita Coelho
JDJoão Dias
João Dias
MSManuela Simões
Manuela Simões
MFMiguel Floro
Miguel Floro
OAOlga Amaral
Olga Amaral
Bread is a widely consumed staple food worldwide and is a source of carbohydrates and energy in the human diet; however, it usually contains low levels of bioactive compounds, such as polyphenols and dietary fiber. Grape pomace (i.e., the residual skins, seeds, and pulp left after vinification) is rich in dietary fiber and antioxidants and is generated in large quantities worldwide. The use of grape pomace as a food ingredient can offer a promising approach, supported by circular economy and sustainable production principles, to add value to a winery by-product and enhance the nutritional profile of foods. This study investigated the nutritional enrichment of breads by incorporating flour produced from red (cv. Alicante Bouschet) and white (cv. Arinto) grape pomace at three levels (5, 10, and 15% w/w). Breads were produced at a pilot scale, using professional bakery fermentation and baking equipment, and analyzed for protein, lipids, sugars, dietary fiber, total phenolic content, antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl [DPPH] and oxygen radical absorbance capacity [ORAC] assays), color, texture, pH, and consumer acceptance (hedonic test). The control and breads fortified with 15% red grape pomace showed similar patterns in protein, fat, and fiber contents were lowest in the control bread and highest in the bread fortified with 15% red grape pomace (15Red). Grape pomace fortification of bread increased the protein, fat, sugar, fiber, and total phenolic compound contents and antioxidant capacity, providing a sustainable strategy to enhance bread antioxidant capacity. Grape pomace is a sustainable, polyphenol-rich ingredient for bread fortification.