Marco Alves

Dr. Marco Alves

orcid

Research Focus & Metrics

Academic Career Length

3Years (2024-Present)

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

Representative Publications

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25 April 2024 in Applied Sciences
Verified
Journal Article
Open access
PDF file
SDSara Dias
Sara Dias
Enrique Pino-HernándezEnrique Pino-Hernández
Enrique Pino-Hernández
DGDiogo Gonçalves
Diogo Gonçalves
DRDuarte Rego
Duarte Rego
Luis M. S. RedondoLuis M. S. Redondo
Luis M. S. Redondo
MAMarco Alves
Marco Alves
This study aimed to investigate the impact of Pulsed Electric Fields (PEF) technology in the extraction of olive oil on a pilot scale, using the “Galega Vulgar” olive variety as raw material. The extraction assisted by PEF had a malaxation time of 30 min and was compared with the traditional process of 45 min of malaxation. The main quality parameters of olive oil and the PEF’s cost-benefit assessment were performed. The incorporation of PEF in olive oil production reduced the malaxation stage by 33% without compromising the yield or extra-virgin classification. This efficiency leads to a potential 12.3% increase in annual olive oil production, with a 12.3% and 36.8% rise in revenue and gross profit, respectively. For small-scale production, the considerable upfront investment required for PEF equipment may be a challenge in terms of return on investment. In this scenario, opting for a renting scheme is the best economic solution, especially given the seasonal nature of olive oil production. In medium- to large-scale production, the investment in PEF is a sound investment since it is possible to achieve, with an equipment cost of EUR 450,000 and a production output of 5 tons per hour, an annual ROI of 20%.

20 April 2025 in Molecules
Verified
Journal Article
Open access
PDF file
NPNelson Pereira
Nelson Pereira
ARAna Cristina Ramos
Ana Cristina Ramos
MAMarco Alves
Marco Alves
Vitor D. AlvesVitor D. Alves
Vitor D. Alves
MMMargarida Moldão-Martins
Margarida Moldão-Martins
MAMarta Abreu
Marta Abreu
Sweet potato (Ipomoea batatas (L.) Lam.; SP) flour enhances food nutrition and bioactivity while functioning as a thickening/gelling agent. This study investigated the impact of two drying methods [hot-air (75 °C/20 h) and freeze-drying (−41–30 °C/70 h)] on the physical–functional properties of flours from three SP varieties: Bonita (white-fleshed), Bellevue (orange-fleshed), and NP1648 (purple-fleshed). Particle size, morphology, water/oil absorption capacities (WAC/OAC), bulk density, swelling power (SwP), water solubility (WS), foaming/emulsifying properties, least gelation concentration (LGC), and gelatinisation temperature (GT) were analysed. Both the drying method and variety significantly influenced these properties. Hot-air-dried flours exhibited bimodal particle distribution, compact microstructure, and aggregated starch granules, yielding higher WAC (≈3.2 g/g) and SwP (≈3.6 g/g). Freeze-dried flours displayed smaller particles, porous microstructure, and fragmented granules, enhancing OAC (≈3.0 g/g) and foaming capacity (≈17.6%). GT was mainly variety-dependent, increasing as Bellevue (74.3 °C) < NP1648 (78.5 °C) < Bonita (82.8 °C), all exceeding commercial potato starch (68.7 °C). NP1648 required lower LGC (10% vs. 16% for others). All flours exhibited high WS (24–39.5%) and emulsifying capacity (≈44%). These results underscore the importance of selecting the appropriate drying method and variety to optimise SP flour functionality for targeted food applications. Freeze-dried flours might suit aerated/oil-retentive products, while hot-air-dried flours could be ideal for moisture-sensitive formulations.

6 December 2024 in Molecules
Verified
Journal Article
Open access
PDF file
NPNelson Pereira
Nelson Pereira
ARAna Cristina Ramos
Ana Cristina Ramos
MAMarco Alves
Marco Alves
Vitor D. AlvesVitor D. Alves
Vitor D. Alves
CRCristina Roseiro
Cristina Roseiro
MAMarta Abreu
Marta Abreu
Sweet potato (Ipomoea batatas (L.) Lam.) is a nutrient-dense crop rich in fibre, minerals, and antioxidant compounds, including carotenoids and phenolic compounds, such as anthocyanins. Dehydrating sweet potato (SP) for flour production enhances its value and produces shelf-stable, health-promoting food products. This study investigated the effects of hot-air drying (HAD: 75 °C/20 h) and freeze-drying (FD: −41–30 °C/70 h) on the bioactive composition of flours from three SP varieties: Bonita (white-fleshed), Bellevue (orange-fleshed), and NP1648 (purple-fleshed). Key assessments included the total phenolic content (TPC), the total carotenoid content (TCC), and the total anthocyanin content (TAC) and the antioxidant activity (DPPH and FRAP). The results revealed distinct raw materials’ bioactive profiles: Bellevue was rich in TCC (49.3 mg of β-carotene/100 g db), NP1648 showed elevated TAC (27.3 mg of cyanidin-3-glucoside/100 g db), and Bonita exhibited minimal content of bioactive compounds. Both drying methods yielded significant losses of bioactive compounds, with the TPC decreasing by over 60%, while TAC and TCC losses did not exceed 32%, revealing higher stability. Multivariate analysis indicated that the variety significantly influenced the bioactive profiles more than the drying method. The interaction between carotenoids and anthocyanins and the SP fibrous composition likely contributed to their stability during drying, indicating that FD showed no advantages over HAD. The appealing colours and high antioxidant content of Bellevue and NP1648 flours suggest their potential as ingredients for enhancing foods’ bioactivity and sensory acceptance.

7 April 2024 in Applied Sciences
Verified
Journal Article
Open access
PDF file
Enrique Pino-HernándezEnrique Pino-Hernández
Enrique Pino-Hernández
MAMarco Alves
Marco Alves
NMNicole Ferreira Moreira
Nicole Ferreira Moreira
VLVasco Lima
Vasco Lima
CPCarlos Alberto Cruz Pinto
Carlos Alberto Cruz Pinto
JSJorge Manuel Alexandre Saraiva
Jorge Manuel Alexandre Saraiva
This study aimed to identify equivalent processing conditions using ultrasound (US), pulsed electric fields (PEF), and high-pressure processing (HPP) for shelf-life extension and to ensure the safety and quality of Reineta Parda apple puree (AP) in comparison to conventional thermal pasteurization (72 °C/15 s, CTP). The processing conditions were selected to achieve at least 5 log CFU/g inactivation of Escherichia coli. HPP (400 MPa/1 min), US (60 °C, 20 kHz/12 min), and PEF (57.2 °C, 10 kV/cm, 70 bipolar pulses of 8 µs each) reduced E. coli counts by 6.6, 6.1, and 5.8 log CFU/g, respectively, thus achieving the pasteurization status. After processing, HPP samples showed higher levels of total antioxidant activity (DPPH and ABTS) compared to the other samples. HPP and PEF samples showed lower browning degrees than the CTP samples. All treatments ensured indigenous microbial stability (below 1 log CFU/g) for at least 30 days under refrigeration. Principal component analysis showed that the HPP samples increased their similarity to the untreated fresh AP during storage based on the pH, total soluble content and water activity, retaining its fresh-like qualities. HPP and PEF were found to be potential alternatives to the CTP of AP, resulting in a safe, minimally processed product with improved antioxidant activity.

30 June 2025 in Processes
Verified
Journal Article
Open access
PDF file
PAPatrícia Antunes
Patrícia Antunes
SDSara Dias
Sara Dias
DGDiogo Gonçalves
Diogo Gonçalves
TOTelma Orvalho
Telma Orvalho
MEMarta B. Evangelista
Marta B. Evangelista
MAMarco Alves
Marco Alves
This study aimed to evaluate the drying kinetics, microstructural features, moisture content, color, pH, aw, texture, acidity, rehydration capacity, and sensorial attributes of strawberry slices processed by different drying methodologies. Strawberry samples were processed by hot air-drying (HA, 60 °C, 0.5 m/s), freeze-drying (FD, 0.055 mbar), and pulsed electric field (PEF)-assisted freeze-drying (PEFFD, 1 kV/cm and 3.2 kJ/kg). PEF pre-treatment significantly increased cell membrane permeability by forming micropores, which led to a significant reduction in the moisture content of up to 8.87% and improved the drying efficiency. Nonetheless, this pre-treatment did not significantly alter the drying rate due to the inherent constraints of the freeze-drying process. PEFFD samples better retained their shape, volume, and visual quality, and exhibited a maximum rehydration capacity of 64.90%. The ascorbic acid retention was found to be higher in the FD and PEFFD when compared to HA. FD and PEFFD samples had an increase in both red and yellow hue. PEF shows promise as a pre-treatment technique, improving both the drying efficiency and strawberry quality. Further studies are needed to assess PEFFD’s industrial scalability and economic feasibility.

2 April 2024
Verified
Book Chapter
Closed access
PDF file
Enrique Pino-HernándezEnrique Pino-Hernández
Enrique Pino-Hernández
PVPaula Valério
Paula Valério
SDSara Dias
Sara Dias
MEMarta B. Evangelista
Marta B. Evangelista
MAMarco Alves
Marco Alves