Color Changes of UHT Milk During Storage

Area of Science:

• Food science
• Dairy technology
• Colorimetry

Background:

• Ultra-high temperature (UHT) processing impacts milk's physical and chemical properties.
• Packaging materials and storage duration are critical factors affecting milk quality.
• Color is a key sensory attribute influencing consumer acceptance of milk products.

Purpose of the Study:

• To investigate the color parameter changes in UHT milk with varying fat content during storage.
• To evaluate the influence of storage duration and milk fat percentage on UHT milk color.
• To analyze color stability using multiple color measurement systems.

Main Methods:

• Color parameters of UHT milk (1.6% and 3.2% fat) were measured using a MOM-color 100 photoelectric tristimulus colorimeter.
• Samples were stored for 0 to 90 days at ambient temperature (20±5°C) in PET-based packaging.
• Color data were analyzed in CIE, CIE L*a*b*, Hünter, and ANLAB systems.

Main Results:

• Mean reflectance in the CIE system showed highly significant changes (p < 0.01) with storage duration and fat content.
• A statistically significant decrease in psychometric chroma b* was observed after 60 days for 1.6% fat milk.
• For 3.2% fat UHT milk, a significant decrease in psychometric chroma b* occurred by the 45th day of storage.

Conclusions:

• Both storage duration and milk fat content significantly affect UHT milk color parameters.
• Lower fat UHT milk exhibits slightly better color stability compared to higher fat milk under the tested conditions.
• Color changes in UHT milk are measurable and quantifiable using tristimulus colorimetry, providing insights into product shelf-life.