Presence of mono-, di- and galactooligosaccharides in commercial lactose-free UHT dairy products

• Published in: Journal of food composition and analysis 2012-12, Vol.28 (2), p.164-169
• Main Authors: Ruiz-Matute, Ana I., Corzo-Martínez, Marta, Montilla, Antonia, Olano, Agustín, Copovi, Paula, Corzo, Nieves
• Format: Article
• Language: English
• Subjects: beverages; Biological and medical sciences; Dairy drinks; enzymatic hydrolysis; Food analysis; Food composition; Food industries; Fundamental and applied biological sciences. Psychology; Furosine; galactooligosaccharides; General aspects; GOS; hydrolysis; lactose; Lactose-free UHT; Lactozym; low lactose milk; manufacturing; Methods of analysis, processing and quality control, regulation, standards; milk; Milk and cheese industries. Ice creams; Milks; Prebiotics; UHT milk
• ISSN: 0889-1575; 1096-0481
• DOI: 10.1016/j.jfca.2012.06.003

► Lactulose was not detected in any of analyzed samples. ► High furosine content indicates that lactose hydrolysis took place before UHT process. ► GOSs were detected in all commercial lactose-free UHT dairy products analyzed. ► In low lactose milk GOS formation may be improved controlling lactose hydrolysis. In this work a study of mono-, di- and galactooligosaccharide (GOS) content as well as the determination of thermal indicators of different commercial lactose-free UHT (LF-UHT) milks and dairy drinks has been carried out. Moreover, GOS formation during hydrolysis of lactose in a commercial UHT milk using Lactozym® pure 6500 was also studied. Presence of GOS was detected in all analyzed samples ranging from 950 to 4350mg/L in LF-UHT milks and from 600 to 2260mg/L in LF-UHT dairy drinks. Their GOS contents correlate roughly with the remaining lactose content of samples. During enzymatic hydrolysis of lactose in commercial UHT milk, the GOS formed reached a maximum about 10,000mg/L when 75–90% of lactose was hydrolyzed and then gradually decreased to values considerably lower than 5000mg/L when over 99% of the lactose was hydrolyzed. Therefore, GOS formation during low lactose milk manufacture might be improved by controlling enzymatic lactose hydrolysis so that it would be possible to elaborate low-lactose milk products able to satisfy the physiological requirements of the majority of intolerant groups and with a GOS content high enough to confer beneficial effect as prebiotic.