Monitoring the changes in UHT whole milk during storage under dynamic and constant temperature profiles

Area of Science:

• Food Science
• Dairy Technology
• Physical Chemistry

Background:

• Ultra-High Temperature (UHT) processing extends milk shelf life.
• Milk quality is sensitive to storage temperature, impacting physical and chemical properties.
• Real-world storage and transport conditions often involve dynamic temperature changes.

Purpose of the Study:

• To investigate the physical and chemical changes in UHT whole milk under constant and dynamic temperature conditions.
• To compare the effects of isothermal versus dynamic temperature storage on UHT milk quality.
• To evaluate the suitability of isothermal conditions for UHT milk shelf-life studies.

Main Methods:

• UHT whole milk samples were stored under three conditions: constant 25°C, constant 41.5°C, and dynamic (alternating between 25°C and 41.5°C every 24 hours).
• Storage duration was up to 158 days.
• Physical and chemical analyses included pH, acidity, electrical conductivity, viscosity, and color measurement.

Main Results:

• The most significant changes occurred at constant 41.5°C, followed by dynamic temperature storage, and then constant 25°C.
• Dynamic temperature storage resulted in changes intermediate between the two constant temperatures, but closer to 25°C.
• Increased acidity, electrical conductivity, and viscosity, along with reduced pH and browning, were observed, particularly at higher temperatures.

Conclusions:

• Constant isothermal conditions may not accurately predict UHT milk shelf life under real-world dynamic temperature fluctuations.
• Dynamic temperature conditions during storage and transport significantly impact UHT milk quality.
• Shelf-life assessments for UHT milk should consider dynamic temperature modeling for greater accuracy.