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<p>This study presents differential scanning calorimetry (DSC) and optical absorption data for <i>Spirulina platensis</i> cultured in Zarrouk’s medium at pH10.2, following exposure to elevated temperatures. Thermal treatment of <i>Spirulina platensis</i> suspension at + 85&#xa0;°C and + 100&#xa0;°C for 15&#xa0;min caused complete loss of chlorophyll a (Chl a) and carotenoid absorption spectra, as well as disappearance of the phycobiliprotein complex (PBPc) heat absorption peak at T = 57 ± 1.5&#xa0;°C and associated metabolic heat dissipation (in the 30–55&#xa0;°C range) from the DSC curve. Only a very weak, sharply defined thermal transition peak remained, with denaturation temperature (T<sub>d</sub>) near 78.5 ± 1.0&#xa0;°C and a narrow interval (ΔT = 0.8 ± 1.0&#xa0;°C). Upon recultivation of <i>Spirulina platensis</i>, the following recoveries were observed: (a) Chl a absorption returned to 89% and 91% of control levels, and the phycocyanin-to-carotenoid absorbance ratio recovered to 80% and 97% after exposure to + 85&#xa0;°C and + 100&#xa0;°C, respectively, and (b) DSC analysis revealed full recovery of both the heat absorption profile and total denaturation enthalpy (ΔH<sub>d</sub>). However, storing suspensions at 24–26&#xa0;°C for 48&#xa0;h triggered significant unfolding of PBPc, reflected by broadening of the ΔT<sub>d</sub> range and emerging new thermal transitions around 65&#xa0;°C, 85&#xa0;°C, and 95&#xa0;°C. These changes were accompanied by reduced PBPc-specific enthalpy (ΔH). The overall ΔH<sub>d</sub> increased slightly that is attributed to emergent high-temperature transitions. These results demonstrate that even brief storage initiates degradation of PBPc and its main components, C-phycocyanin (C-PC) and C-allophycocyanin (C-APC), despite prior thermal recovery—highlighting both the resilience and vulnerability of <i>Spirulina platensis</i> bioactive structures.</p>

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Thermodynamic stability of Spirulina platensis and phycobiliprotein complex after exposure to high temperatures

  • 期刊论文

  • 发表日期：

    2026年8月5日

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  • Jamlet Monaselidze,
  • Eugeni Kiziria,
  • Eteri Gelagutashvili,
  • Maya Gorgoshidze,
  • Shota Barbakadze,
  • Giorgi Majagaladze,
  • Maya Kiladze

摘要

This study presents differential scanning calorimetry (DSC) and optical absorption data for Spirulina platensis cultured in Zarrouk’s medium at pH10.2, following exposure to elevated temperatures. Thermal treatment of Spirulina platensis suspension at + 85 °C and + 100 °C for 15 min caused complete loss of chlorophyll a (Chl a) and carotenoid absorption spectra, as well as disappearance of the phycobiliprotein complex (PBPc) heat absorption peak at T = 57 ± 1.5 °C and associated metabolic heat dissipation (in the 30–55 °C range) from the DSC curve. Only a very weak, sharply defined thermal transition peak remained, with denaturation temperature (Td) near 78.5 ± 1.0 °C and a narrow interval (ΔT = 0.8 ± 1.0 °C). Upon recultivation of Spirulina platensis, the following recoveries were observed: (a) Chl a absorption returned to 89% and 91% of control levels, and the phycocyanin-to-carotenoid absorbance ratio recovered to 80% and 97% after exposure to + 85 °C and + 100 °C, respectively, and (b) DSC analysis revealed full recovery of both the heat absorption profile and total denaturation enthalpy (ΔHd). However, storing suspensions at 24–26 °C for 48 h triggered significant unfolding of PBPc, reflected by broadening of the ΔTd range and emerging new thermal transitions around 65 °C, 85 °C, and 95 °C. These changes were accompanied by reduced PBPc-specific enthalpy (ΔH). The overall ΔHd increased slightly that is attributed to emergent high-temperature transitions. These results demonstrate that even brief storage initiates degradation of PBPc and its main components, C-phycocyanin (C-PC) and C-allophycocyanin (C-APC), despite prior thermal recovery—highlighting both the resilience and vulnerability of Spirulina platensis bioactive structures.