Changes in furfural compounds during storage of infant milks

The progress of the Maillard reaction in two infant milks (liquid and powdered forms of the same commercial brand) was monitored for 9 months of storage at 20, 30, and 37 degrees C. An increase in furfural compounds [hydroxymethylfurfural (HMF) and furfural (F)] was observed while no changes in available lysine occurred during storage at any temperature. In reconstituted powdered infant milk, at the three storage temperatures, the contents of free and total HMF ranged from 10.3 to 23.5 mu mol/L and from 15.0 to 34.7 mu mol/L, respectively. The content of free and total F ranged from 1.1 to 5.3 mu mol/L and from 1.8 to 6.8 mu mol/L, respectively. Free and total HMF content in liquid infant milk ranged from 0.6 to 1.6 mu mol/L and from 9.0 to 12.2 mu mol/L, respectively. The content of free and total F ranged from 0.3 to 0.6 mu mol/L and from 1.4 to 2.3 mu mol/L, respectively. Although free and total HMF and F were always higher in powdered milk than in liquid infant milk, in the latter the ratio total HMF/free HMF was more than 10 times that in powdered infant milk. On the basis of the increase in furfural compounds and by using the sum of free HMF and free F, an equation has been derived by which the shelf life of such products can be predicted.