https://hdl.handle.net/10259/5827 Thu, 28 May 2026 16:29:32 GMT 2026-05-28T16:29:32Z https://hdl.handle.net/10259/11720 Physical–Chemical and Microbiological Characterisation of Blueberry By-Products (Vaccinium myrtillus L.) as Potential Food Ingredients Ortega Heras, Miriam; González San José, Mª Luisa; Hortigüela Delgado, Ruth; Fernández Varona, Ángela; Rodríguez, Verónica; Melero Gil, Beatriz The production of blueberry juice generates large quantities of waste products such as skins, pulp and seeds. These by-products contain high levels of bioactive compounds and are suitable for use as functional ingredients in food systems. In this study three powdered products obtained from blueberry pomace—with skins and seeds, seedless, and with seeds—have been physically–chemically and microbiologically characterised as being the individual anthocyanins and phenolic compounds identified by HPLC-QTOF. Furthermore, to ensure product safety, the effect of a heat treatment at 90 °C for 30, 60, 90 and 120 min was also studied. The three products showed high concentrations of fibre, phosphorus, calcium and potassium. The two products with skins also showed high levels of anthocyanins, phenolic compounds and antioxidant activity. The product from seeds had the highest load of Aerobic Mesophilic Bacteria and Enterobacteriaceae whereas Bacillus spp. was found in the three products. Heat treatment at 90 °C for 90 min reduced the Aerobic Mesophilic Bacteria count below the detection limit. This treatment did not significantly affect the anthocyanin content, although some anthocyanins seemed to be more thermolabile than others, and increased the concentration of the phenolic acids and their derivatives. This study demonstrates the high nutritional and functional value of blueberry by-products, highlighting their potential as sustainable ingredients in the food industry and their viability after a heat treatment. Fri, 01 May 2026 00:00:00 GMT https://hdl.handle.net/10259/11720 2026-05-01T00:00:00Z https://hdl.handle.net/10259/11287 Genome-Wide association study to identify genetic markers associated with Campylobacter jejuni motility Ortega Sanz, Irene; Rovira Carballido, Jordi; Megías, Gregoria; Rivero Pérez, Maria Dolores; Melero Gil, Beatriz The ability of Campylobacter jejuni to survive and persist under harsh conditions is linked to the presence of flagella. This structure promotes the motility of the bacteria towards their optimum environment. The aim of this study was to examine the genetic basis for motility within 136 C. jejuni isolates through two different Genome-Wide Association Studies, gene presence/absence and Single Nucleotide Polymorphisms (SNPs). The motility phenotype was widely distributed across the phylogeny with large intra-lineage swarming performance variabilities. Accessory genes significantly associated with motility were found in four key genomic regions. One of these regions affected the Cj0727-Cj0733 operon, that encodes a putative ABC transporter system for phosphate uptake, while other influenced the capsule biosynthesis locus. Multiple SNPs mostly linked to increased motility were also discovered in clusters of genes, with special relevance to transport and membrane proteins. Therefore, the capsule and membrane composition might influence nutrient transfer, further impacting the protonmotive force that drives flagellar motor rotation in C. jejuni. The study provides novel genetic markers with a potential role in the motility phenotype of the pathogen. Fri, 01 Aug 2025 00:00:00 GMT https://hdl.handle.net/10259/11287 2025-08-01T00:00:00Z https://hdl.handle.net/10259/11286 High-Pressure Processing for Cold Brew Coffee: Safety and Quality Assessment under Refrigerated and Ambient Storage Polanco-Estibález, Berta; García-Santa-Cruz, Rodrigo; Queirós, Rui P.; Serment-Moreno, Vinicio; González Angulo, Mario; Tonello Samson, Carole; Rivero Pérez, Maria Dolores Cold brew coffee (CBC) has gained in popularity due to its distinct sensory experience. However, CBC can pose a risk for bacterial pathogens if not stored properly. High-Pressure Processing (HPP) is a nonthermal technology that can improve the safety of CBC while maintaining its quality. In this study, CBC made from ground roasted coffee grains was processed at 600 MPa for 3 min and stored at 4 or 23 °C for 90 days. The microbiological quality indicators remained stable throughout the study period. Physicochemical and quality parameters, such as pH, total dissolved solids, titratable acidity, color, total phenolic compounds and antioxidant activity, were not significantly affected by HPP. Both unprocessed and HPP CBC samples showed changes in pH, titratable acidity and color stability after 60 days at 23 °C. Unprocessed CBC samples spiked with Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enterica showed decreased counts, but the pathogens were still detectable after 60 days at 4 °C and after 90 days at 23 °C. HPP achieved a >6-log10 reduction in the species tested, with non-detectable levels for at least 90 days at both storage temperatures. These findings suggest that HPP can effectively control vegetative pathogens and spoilage microorganisms in CBC while preserving its quality attributes. Fri, 01 Dec 2023 00:00:00 GMT https://hdl.handle.net/10259/11286 2023-12-01T00:00:00Z https://hdl.handle.net/10259/11219 Preliminary Study of the Effect of Short Maceration with Cherry and Oak Wood Chips on the Volatile Composition of Different Craft Beers Correia, Ana C.; González San José, Mª Luisa; Ortega Heras, Miriam; Jordão, António M. In the last few years, the production and consumption of craft beers has increased notably. However, there is restricted knowledge about the potential impact of chips from different wood species on beer quality. Thus, this work aimed to evaluate the effect of the addition of wood chips from cherry and oak species—after the fermentation was completed and during a brief maceration time—on the volatile composition of three different beer groups (Ale, Lager, and Porter) through a headspace solid-phase dynamic extraction (HS-SPDE) and GC-MS analysis. Fifty-six volatile compounds from different chemical families (esters, alcohols, terpenes, acids, aldehydes, ketones, and pyrazines) were detected, identified, and considered in this study. In general, the volatile composition of the beers macerated with wood chips was very similar to that of the control beers. However, the control beers showed higher volatile compound levels. The results suggest potential interactions between beer volatile compounds and the wood chips during maceration. The outcomes of this research could be of practical interest to brewers since they could improve the knowledge of the impact of short-time contact and low wood chip concentration on the volatile composition of different craft beers. Fri, 01 Sep 2023 00:00:00 GMT https://hdl.handle.net/10259/11219 2023-09-01T00:00:00Z