Odor changes in breast milk during different storage temperatures and times using GC × GC-O-MS

Breastfeeding is generally the preferred way that most mothers will choose. It is common to store expressed breast milk in the refrigerator in many families. However, there is a phenomenon that infants may refuse to consume stored breast milk, presumably due to changes in odor. Thus, the odor changes in breast milk stored at 4 °C for 72 h and at -20 °C for 60 d were studied. Compared with fresh breast milk, 7 and 16 odor compounds were newly detected by SPME and GC × GC-O-MS when breast milk was stored at 4 and -20 °C, respectively. The concentration of (E)-2-decenal, octanal, hexanal, 1-octen-3-ol, 2-pentylfuran, lauric acid, decanoic acid and hexanoic acid significantly increased after storage at 4 °C for 36 h and -20 °C for 30 d. In addition, the proportion of acids increased, whereas that of aldehydes decreased during storage. Chemometric analysis with OPLS-DA suggested that breast milk should be stored at 4 °C for less than 36 h and at -20 °C for less than 30 d for maximum preservation of the original odors.