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- Microbial and pest contamination in nuts: Radio frequency disinfestation and controlled atmosphere preservation – A reviewPublication . Liberal, Ângela; Fernandes, Ângela; Moreira, Jorge; Fernandes, Natércia; Gonçalves, Alexandre; Ferreira, Isabel C.F.R.; Barros, LillianNuts are increasingly recognized for their rich nutritional profile and bioactive potential, making them a sig- nificant economic contributor globally. However, the commercialization of nuts necessitates stringent quality control measures to mitigate infestations by insect pests and microorganisms, which can lead to rapid deterio- ration both pre- and post-harvest. Contamination often arises from inadequate practices in harvesting, packaging, storage, and transportation, heightening the risk of pathogen infection and mycotoxin contamination. To address these challenges, innovative preservation techniques are essential for enhancing food safety and extending shelf- life without compromising quality. Radiofrequency (RF) technology has emerged as a promising solution in food processing, utilizing volumetric heating for effective disinfestation, pathogen pasteurization, drying, and blanching while maintaining product integrity. In contrast, Controlled Atmosphere (CA) storage employs gas composition control to create low-oxygen environments that inhibit microbial growth during storage. This re- view aims to provide a comprehensive overview of nut safety and preservation by identifying key contamination sources and the microorganisms that target nuts. It will analyze the effectiveness of RF and CA technologies in preserving and decontaminating nuts. By exploring these advanced methods, this study highlights their potential to surpass conventional processes, ultimately improving nut safety and quality throughout the supply chain.
- Incorporation of pumpkin peel extract into a pumpkin pulp formulation as a natural preservativePublication . Leichtweis, Maria Gabriela; Molina, Adriana K.; Petropoulos, Spyridon Α.; Gonçalves, Alexandre; Azevedo, Miguel; Silva, Beatriz Nunes; Pires, Tânia C.S.P.; Oliveira, Beatriz; Barros, Lillian; Pereira, CarlaExtract rich in preservative compounds was obtained from pumpkin peels by heat-assisted extraction, with water as solvent. This extract was incorporated into a ready-to-use pumpkin pulp product, in a concentration of 5g/kg, in order to replace the use of potassium sorbate (control). The product shelf-life was evaluated regarding microbial load and colour stability considering the best before date of the commercial product (30 days). For that purpose, the samples were stored at room temperature and evaluated on the day of production and after 7, 14, 21, 30, and 45 days of storage. Microbial load, it was evaluated in terms of aerobic plate count (total viable count; ISO 4833-2:2013), coliforms (and E. coli; ISO 4832:2006), and yeasts and moulds (ISO 21527-1/2:2008). For the physicochemical parameters, the colour was assessed by chromatic analysis in the CIELAB colour space, measuring L(lightness), a (redness), and b(yellowness) to obtain the palette of tones and the chroma values of the pulp formulations. In both pulp products, with the addition of extract and control, no microbial growth was evidenced up to the 45th days of storage. This result demonstrates the great efficiency of using the natural extract to replace potassium sorbate, a traditional but artificial preservative widely used in the food industry. Meanwhile, despite the satisfactory result obtained in terms of antimicrobial protection, the colour was clearly affected. Through both the RGB and L, a, and b parameters it was possible to verify the loss of colour of the pulp formulation containing the natural extract during the storage days, while in the control formulation it was less noticeable. Considering the preservative potential of the extract, new formulations will be tested with different concentrations, aiming a healthier pulp product and promoting a circular economy.