Isomerization of retinyl palmitate in fortified skim milk under retail fluorescent lighting

Effects of Pro‐Oxidants and Antioxidants on the Total Antioxidant Capacity and Lipid Oxidation Products of Milk During Refrigerated Storage

“…Exposure to light contributes to the degradation of α‐tocopherol in milk due to its chemical quenching of singlet oxygen and decomposition to tocopherol quinones and tocopherols quinone epoxides (Clough and others ; Slots and others ; Choe and Min ). Retinyl palmitate in milk is isomerized to 9‐ cis ‐retinyl palmitate and 13‐ cis ‐retinyl palmitate, resulting in reduced vitamin A activity (Murphy and others ).…”

“…The degradation of vitamins A and E in the presence of light is likely responsible for the lack of an antioxidant effect on the FRAP value after day 0. Murphy and others () reported that vitamin A can undergo photoisomerization in the presence of light, leading to the formation of cis isomers with reduced antioxidant activity. The oxidation of α‐tocopherol to tocopheryl radicals, which decompose to tocopherol quinone and tocopherol quinone epoxides, would also contribute to a reduction in antioxidant activity (Clough and others ; Choe and Min ).…”

Vitamin A stability in triple fortified extruded, artificial rice grains containing iron, zinc and vitamin A

“…RP retention was 18% higher ( P < 0.05) after storage for 18 weeks in AF bags as compared to storage in PE bags, which resulted in about 40% degradation. These findings are in agreement with results published by Murphy et al. (1988) who investigated the extent of isomerisation and degradation of all trans retinyl palmitate‐fortified skim milk in three types of containers (paperboard, PE and glass) under fluorescent lighting.…”

Stabilization of Vitamin A in a Synthetic Rice Premix

“…Rate constants for degradation were determined by plotting linear regression of In (% remaining) on the time using the SAS statistical package (Gary, NC) (Murphy et al, 1988). Standard deviations and % error were estimated.…”