Does vitamin fortification affect light oxidation in fluid skim milk?

Area of Science:

• Food Science
• Dairy Science
• Nutritional Biochemistry

Background:

• Milk's susceptibility to light oxidation leads to off-flavors from riboflavin and tetrapyrrole photoxidation.
• Vitamin A fortification, particularly water-dispersible forms, has been linked to off-flavors due to vitamin degradation products.

Purpose of the Study:

• To investigate the impact of vitamin fortification on light-induced oxidation in pasteurized fluid skim milk.
• To differentiate the effects of light exposure on vitamin premixes versus fortified milk.

Main Methods:

• Aroma profiles and volatile compounds of light-exposed vitamin premixes (fluorescent and LED light) were analyzed using GC-MS and olfactometry.
• Skim milk fortified with vitamins A and D was exposed to light, and sensory profiles, vitamin degradation, and volatile compounds were assessed.
• Ultra-high-performance liquid chromatography and GC-MS were employed to quantify vitamin degradation and lipid oxidation products.

Main Results:

• Light exposure degraded riboflavin, vitamin A, and vitamin D, consistent with prior research.
• No significant effect of vitamin fortification on typical light oxidation off-flavors (cardboard, mushroom) or lipid oxidation volatiles was observed.
• Oil-based vitamin A fortification resulted in a perfumey/floral aroma, indicating differential light impact based on vitamin matrix.

Conclusions:

• Vitamin fortification at current levels does not protect fluid milk from developing light oxidation-related off-flavors.
• The matrix of vitamin fortification (oil vs. water) influences the type of off-flavors generated under light exposure.