The stability of gal-polyols and oligosaccharides during pasteurization at a low pH

The aim of the work was to compare the stability of gal-xylitol and gal-sorbitol (synthesized with β-galactosidase from lactose and polyols) with the stability of lactitol, galactooligosaccharides (GOSs) and fructooligosaccharides (FOSs) in the conditions of pasteurization of juices and fruit drinks. Juice and drinks of a pH ranging from 2.7 to 4.2 were used. Pasteurization was carried out in the following variants (depending on the juice or fruit drink used): 95 °C 30 s; 95 °C 30 s+84 °C 10 or 20 min; 99 °C 30 s+88 °C 25 min. It has been shown that galactosyl derivatives of polyols demonstrate high stability in the pasteurization conditions. It is comparable to the resistance to heating that is characteristic of GOSs and lactitol. The minimum of 97% of the initial amount of gal-polyols remains in an unchanged form after thermal preservation, while FOSs are hydrolysed during pasteurization. The degree of hydrolysis of these saccharides is higher the lower the pH and the longer the pasteurization time. The pasteurization of a black currant drink (pH=3.1; 95 °C 30 s+84 °C 10 min) causes the loss of approx. 50% of tetrasaccharide and up to 30% of trisaccharides.