IMPACT OF PASTEURIZATION AND PROCEDURES COMMONLY USED TO RETHERMALIZESTORED HUMAN-MILK ON FOLATE CONTENT

Severe heat treatment dramatically reduces milk folate content; howeve r, the impact of pasteurization and rethermalization techniques used b y mothers to thaw and warm banked milk is unknown. The purpose of this study was to determine the effect of pasteurization, microwaving and warming of milk in a tap water bath (conventional heating) on milk fol ate content and form. Human milk (n=10) collected by complete breast e xpression was pasteurized (62.5 degrees C for 30 minutes), microwaved (720 watts, high power for 30 seconds) or conventionally heated (40 de grees C for 10 minutes). Cow (n=10) and goat (n=10) milk was pasteuriz ed as above. The folate content of milk samples was determined using a differential microbiological technique with and without added folate conjugase. A 16% reduction in human milk folate content was noted foll owing pasteurization. Microwaving and conventional heating did not cau se a reduction in total milk folate content. A similar reduction in mi lk folate content was noted following pasteurization of cow milk (12%) , but goat milk folate content was not significantly affected. Additio n of ascorbate (1%) before pasteurization of human and cow milk amelio rated these losses. In a separate experiment, we found that ascorbate added to cow milk at a concentration of 0.01% was sufficient to protec t folate against degradation during pasteurization. The mean folate co ntent of human, cow, and goat milk was 113.7+/-3.7 (mean+/-SEM), 142.8 +/-6.8 and 21.3+/-9.0 nmol/L, respectively. Results suggest that therm al techniques typically used by mothers to thaw and warm banked milk w ould provide an infant with the recommended intake of folate. Pasteuri zation (62.5 degrees C for 30 minutes) without the addition of ascorba te may result in intakes of folate below recommended levels for some i nfants.