The Comparative Value of Chocolate and Whole Milk as a Source of Riboflavin for the Rat

Several recent investigations have shown that the photochemical destruction of riboflavin in milk is quite rapid. Peterson et al. (1) found losses of riboflavin, as detected by the fluorometric procedure, in pint glass bottles of whole milk exposed to direct sunlight of 28, 50, 66 and 72 per cent after 30, 90, 120 and 210 minutes of exposure, respectively. Similar reports were given by Ziegler (4). Shetlar et al. (2) reported that chocolate milks lose riboflavin very slowly when exposed to sunlight, the average loss of riboflavin after 4 hours for five different brands being about 12 per cent as compared to a loss of 80 per cent for whole milk. Warner and Sutton (3) recently reported that calves fed on a photolyzed whole milk diet developed characteristic riboflavin deficiency symptoms. The reports by the above authors indicate the importance of preventing the exposure of milk to sunlight with the resultant inactivation of part of the riboflavin. Loss of riboflavin in whole milk due to light exposure easily could result in at least a partial riboflavin deficiency. Chocolate milk as manufactured compares favorably to whole milk in riboflavin content as determined by the fluorometric procedure developed by Shetlar et al. (2). The much slower photochemical loss of riboflavin in chocolate milk perhaps is due to the extra protection afforded by the added chocolate. This would indicate that chocolate milk might prove advantageous if the milk during delivery was subjected to much exposure to light, provided that the chocolate does not interfere with the assimilation of riboflavin after consumption.