Abstract：
The composition of melanoidins in dried apple that affects quality remains unclear. The composition and structure of melanoidins in dried apple slices by hot air drying (HAAM), instant controlled pressure drop drying (DICAM), and vacuum freeze-drying (FDAM) were investigated. It showed that the melanoidins were highly heterogeneous mixtures with a light-yellow color and blue-green fluorescence, belonging to polysaccharide-type melanoidins. Specifically, HAAM had a large molecular weight (929.5 g/mol) and wide molecular weight distribution, with more double-bond conjugated systems. DICAM (610.9 g/mol), possessing the strongest fluorescence intensity, was mainly composed of compounds with fewer π-conjugated structures and more electron-donating groups. As a control, the low level of Maillard reaction in FDAM resulted in the formation of the smallest molecular weight (458.6 g/mol) with weak fluorescence intensity. Moreover, 10 compounds were tentatively identified in apple melanoidins. This study provides the foundation for the future functional preparation of apple melanoidins.
摘要：
影响质量的干苹果中黑色素的成分尚不清楚。通过热风干燥（HAAM）干燥的苹果片中黑色素的组成和结构，即时控制压降干燥（DICAM），和真空冷冻干燥（FDAM）进行了研究。结果表明，黑素是高度异质的混合物，具有浅黄色和蓝绿色荧光，属于多糖型黑色素。具体来说,HAAM具有大的分子量（929.5g/mol）和宽的分子量分布，有更多的双键共轭体系。DICAM（610.9g/mol），具有最强的荧光强度，主要由π共轭结构较少和给电子基团较多的化合物组成。作为一种控制，FDAM中低水平的美拉德反应导致形成最小的分子量(458.6g/mol),荧光强度弱。此外，在苹果黑色素中初步鉴定出10个化合物。本研究为今后苹果黑色素的功能性制备奠定了基础。
