Jansson Therese, Clausen Morten R, Sundekilde Ulrik K, Eggers Nina, Nyegaard Steffen, Larsen Lotte B, Ray Colin, Sundgren Anja, Andersen Henrik J, Bertram Hanne C
Department of Food Science, Aarhus University , Kirstinebjergvej 10, DK-5792 Aarslev, Denmark.
J Agric Food Chem. 2014 Aug 6;62(31):7886-96. doi: 10.1021/jf501671z. Epub 2014 Jul 25.
The enzymatic hydrolysis of lactose to glucose and galactose gives rise to reactions that change the chemistry and quality of ambient-stored lactose-hydrolyzed ultra-high-temperature (UHT) milk. The aim of the present study was to investigate and compare chemical changes in lactose-hydrolyzed and conventional UHT milk during a 9 month ambient storage period. Several complementary analyses of volatiles, free amino acids, acetate, furosine, and level of free amino terminals were concluded. The analyses revealed an increased level of free amino acids and an increased formation rate of specific compounds such as furosine and 2-methylbutanal in lactose-hydrolyzed UHT milk compared to conventional UHT milk during storage. These observations indicate more favorable conditions for Maillard and subsequent reactions in lactose-hydrolyzed milk compared to conventional UHT milk stored at ambient temperature. Furthermore, it is postulated that proteolytic activity from the lactase-enzyme preparation may be responsible for the observed higher levels of free amino acids in lactose-hydrolyzed UHT milk.
乳糖酶解为葡萄糖和半乳糖会引发一些反应，这些反应会改变常温储存的乳糖水解超高温（UHT）奶的化学性质和品质。本研究的目的是调查和比较乳糖水解UHT奶和传统UHT奶在9个月常温储存期内的化学变化。我们完成了对挥发性物质、游离氨基酸、乙酸盐、糠氨酸以及游离氨基末端水平的多项补充分析。分析结果显示，与传统UHT奶相比，在储存期间，乳糖水解UHT奶中游离氨基酸水平升高，糠氨酸和2-甲基丁醛等特定化合物的生成速率也有所增加。这些观察结果表明，与常温储存的传统UHT奶相比，乳糖水解奶中发生美拉德反应及后续反应的条件更为有利。此外，据推测，乳糖酶制剂的蛋白水解活性可能是乳糖水解UHT奶中游离氨基酸水平较高的原因。
