Andrews G R, Prasad S K
J Dairy Res. 1987 May;54(2):207-18. doi: 10.1017/s0022029900025358.
Milk ultrafiltrate and milks of varying protein, citrate and phosphate concentrations were heated in sealed containers. Protein was found not to be involved in the mechanism of formation of lactulose, but increasing the protein content of milk reduced the concentration of lactulose after heating. This was considered to be due to increased condensation of lactose and lactulose with amino groups of the protein. Less lactulose was formed in milk ultrafiltrate than in skimmed milk accorded the same heat treatment, which was attributed to the buffering capacity of the milk protein in skimmed milk. Activation energies for lactulose formation in skimmed milk and in ultrafiltrate were 128 and 131 kJ/mol respectively. Citrate and phosphate catalysed the formation of lactulose. It is proposed that the formation of free lactulose in heated milk and ultrafiltrate proceeds exclusively by the Lobry de Bruyn-Alberda van Ekenstein transformation with the naturally occurring phosphate and citrate acting as base catalysts.
将牛奶超滤物以及不同蛋白质、柠檬酸盐和磷酸盐浓度的牛奶在密封容器中加热。研究发现，蛋白质不参与乳果糖形成的机制，但增加牛奶中的蛋白质含量会降低加热后乳果糖的浓度。这被认为是由于乳糖和乳果糖与蛋白质氨基的缩合增加所致。在相同热处理条件下，牛奶超滤物中形成的乳果糖比脱脂牛奶中少，这归因于脱脂牛奶中乳蛋白的缓冲能力。脱脂牛奶和超滤物中乳果糖形成的活化能分别为128和131 kJ/mol。柠檬酸盐和磷酸盐催化乳果糖的形成。有人提出，加热牛奶和超滤物中游离乳果糖的形成完全通过洛布里·德·布鲁因 - 阿尔贝达·范·埃肯斯坦转化进行，天然存在的磷酸盐和柠檬酸盐作为碱催化剂。
