From Sun to Air Drying: Comparative Quality Evolution of Dried Octopus vulgaris

This study aimed to evaluate the effects of two drying methods on the physicochemical and microbiological quality of Octopus vulgaris. Samples were dried using sun drying (SD) at 28 ± 0.75 °C and convective air drying (CAD) at 30 ± 0.12 °C. Drying and rehydration kinetics were investigated. Physicochemical analyses included pH, water activity (aᵥ), color parameters, total volatile basic nitrogen (TVB-N), and trimethylamine (TMA), while microbiological quality was assessed through total viable count (TVC) and yeast and mold (YM) enumeration using standard methods. Quality attributes of the dried products were analyzed and compared using analysis of variance (ANOVA). CAD resulted in a significantly higher drying rate, whereas no significant differences were observed in rehydration behavior between the two drying methods. Drying led to the inhibition of yeasts and molds in both treatments, while lower total viable counts were observed in CAD-treated samples. TVB-N content increased after drying, from 5.1 ± 1.2 mg N/100 g in fresh samples to 6.0 ± 0.59 and 9.46 ± 1.81 mg N/100 g in CAD- and SD-treated samples, respectively. A similar trend was observed for TMA levels. Sun-dried octopus exhibited higher total color difference (ΔE) and browning index (BI) values, indicating more pronounced color changes and intensified non-enzymatic browning reactions. Overall, low-temperature convective air drying at 30 °C appears to be a suitable method for preserving the quality of dried octopus.