Chilled Pacu (Piaractus mesopotamicus) fillets: Modeling Pseudomonas spp. and psychrotrophic bacteria growth and monitoring spoilage indicators by 1H NMR and GC–MS during storage

• Published in: International journal of food microbiology 2024-04, Vol.415, p.110645-110645, Article 110645
• Main Authors: Baptista, Rafaela C., Oliveira, Rodrigo B.A., Câmara, Antonio A., Lang, Émilie, dos Santos, Juliana L.P., Pavani, Matheus, Guerreiro, Tatiane M., Catharino, Rodrigo R., Filho, Elenilson G.A., Rodrigues, Sueli, de Brito, Edy S., Alvarenga, Verônica O., Bicca, Gerson B., Sant'Ana, Anderson S.
• Format: Article
• Language: English
• Subjects: Biomarkers; Chilling; decision making; fish; food microbiology; Freshwater fish; growth models; microbial growth; octenol; Piaractus mesopotamicus; Predictive microbiology; Pseudomonas; refrigeration; Shelf-life; Spoilage; storage time; temperature; volatile organic compounds
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2024.110645

This study aimed to assess the growth of Pseudomonas spp. and psychrotrophic bacteria in chilled Pacu (Piaractus mesopotamicus), a native South American fish, stored under chilling conditions (0 to 10 °C) through the use of predictive models under isothermal and non-isothermal conditions. Growth kinetic parameters, maximum growth rate (μmax, 1/h), lag time (tLag, h), and (Nmax, Log10 CFU/g) were estimated using the Baranyi and Roberts microbial growth model. Both kinetic parameters, growth rate and lag time, were significantly influenced by temperature (P 0.97 and were further validated under non-isothermal conditions. The model's performance was considered acceptable to predict the growth of Pseudomonas spp. and psychrotrophic bacteria in refrigerated Pacu fillets with bias and accuracy factors between 1.24 and 1.49 (fail-safe) and 1.45–1.49, respectively. Fish biomarkers and spoilage indicators were assessed during storage at 0, 4, and 10 °C. Volatile organic compounds, VOCs (1-hexanol, nonanal, octenol, and indicators 2-ethyl-1-hexanol) showed different behavior with storage time (P > 0.05). 1H NMR analysis confirmed increased enzymatic and microbial activity in Pacu fillets stored at 10 °C compared to 0 °C. The developed and validated models obtained in this study can be used as a tool for decision-making on the shelf-life and quality of refrigerated Pacu fillets stored under dynamic conditions from 0 to 10 °C. •Growth models of Pseudomonas and psychrotrophic bacteria in chilled Pacu (0-10 °C)•Secondary growth models were validated under non-isothermal conditions•Volatile organic compounds and biomarkers showed diverse behavior with storage time•1H NMR indicated that Pacu fillets presented higher spoilage at 10 °C than at 0 °C•Models can predict the shelf-life of Pacu fillets in dynamic conditions (0-10 °C)