Effects of Light on Riboflavin and Ascorbic Acid in Freshly Expressed Human Milk

Abstract

Millions of dollars each year is spent funding dairy research to better understand every aspect of milk processing, storage, handling, and shelf life. The dairy industry has shown that in animal milks vitamin C is photo-oxidized when exposed to light, which can cause a cascade of other nutrients that may be affected. Expressed human breast milk has had limited research published, mainly recommendations for storage duration secondary to bacterial growth, with scant research on nutrient quality during handling compared to the animal models. In this study, freshly expressed human milk was placed in containers of varying color/UV sensitivity and exposed to light over 6 hours. The laboratory analysis showed riboflavin and ascorbic acid concentrations rapidly decreased in clear containers. The containers wrapped in foil and those of amber color appear to have prevented the photo-oxidation of riboflavin and ascorbic acid. The concentrations of riboflavin and ascorbic acid consistently decreased over a relatively short space of time when stored in translucent containers. The control of photo-oxidation is an important component of maintaining nutrient quality, particularly in foods intended for infants. Minimizing light exposure would provide protection to the nutrients that are susceptible to oxidation. More research is needed to update recommendation for handling expressed human milk to ensure integrity of fragile nutrients in expressed human milk. The authors concluded that amber and other darkened containers that can prevent photo-oxidation of the breast milk could prevent degradation of certain nutrients in stored expressed human milk and possibly the shelf-life. While more research is needed to further identify harmful and helpful aspects of breast milk storage, these findings can establish a foundational understanding and new perspective on human breast milk handling.Keywords: Breast milk; Ascorbic acid; Riboflavin; Storage; Photo-oxidation; Dairy expressed and a baseline sample was immediately analyzed. Aliquots were split between the variable micro-centrifuge 1mL tubes. Into each of the tubes, clear, opaque, blue, green, amber and foil. 1mL of milk was pipetted gently while placing the tip against the side of the tube in order to avoid oxidation. The tubes were then exposed to light and samples were removed from each tube at the respective times of 30 minutes, 1 hour, 2 hours, 4 hours, and 6 hours. Twenty-seven samples were analyzed in triplicate. Every sample taken for testing was placed in amber HPLC vials, wrapped in foil under red light working conditions, and taken immediately for analysis under red-light working conditions. Riboflavin and ascorbic acid concentrations were identified and quantified on the basis of standard solutions used as external standards (R=0.9827). Isocratic chromatographic separation was carried out using a mobile phase of Milli-Q water with acetic acid (0.1%, v/v) and methanol in a relative proportion of 95:5 (v/v) using all HPLC grade reagents. One microliter of filtrate wa...

Protective influence of heat treatment on the light-induced riboflavin (vitamin B2) degradation in dairy products

“…Milk contains 1.75 mg/L riboflavin and is the most important source of riboflavin in many nations [2,3]. Milk and dairy products are particularly sensitive to light, and photo-initiated reactions not only affect the sensory quality but may also lead to the formation of toxic compounds in certain products and degradation of nutrients [2,4]. Riboflavin was the primary factor responsible for the development of light-induced oxidized flavor.…”