Purslane-Fortified Yogurt: In-Line Process Control by FT-NIR Spectroscopy and Storage Monitoring

Area of Science:

• Food Science and Technology
• Biotechnology
• Spectroscopy

Background:

• Yogurt fortification with purslane (Portulaca oleracea L.) may impact fermentation and final product characteristics.
• Monitoring lactic acid fermentation is crucial for consistent yogurt quality.

Purpose of the Study:

• To evaluate Fourier Transform-Near Infrared (FT-NIR) spectroscopy for in-line monitoring of lactic acid fermentation in purslane-fortified yogurt.
• To compare FT-NIR spectroscopy with rheology for fermentation monitoring.
• To assess changes in yogurt properties during storage.

Main Methods:

• Set-type yogurts with and without lyophilized purslane leaves (0.55%) were produced and stored at 4 °C for 18 days.
• Lactic acid bacteria counts, rheological properties (complex modulus), and FT-NIR spectra were analyzed.
• Data were processed using Principal Component Analysis and the Gompertz equation.

Main Results:

• Purslane addition did not inhibit bacterial growth during fermentation.
• Purslane-fortified yogurt exhibited higher complex modulus values (360 Pa) compared to the control (172 Pa).
• FT-NIR spectroscopy, analyzed with the Gompertz equation, detected fermentation critical points approximately 18% earlier than rheology, indicating superior monitoring capability.
• No significant changes in microbial or textural properties were observed during storage, confirming product stability.

Conclusions:

• FT-NIR spectroscopy is a suitable tool for in-line monitoring of lactic acid fermentation in purslane-fortified yogurt.
• Purslane fortification enhances yogurt rheological properties without compromising microbial or textural stability during storage.
• The integration of FT-NIR spectroscopy and kinetic modeling (Gompertz equation) allows for precise control over yogurt production processes.