Kinetics of lactose hydrolysis and galactooligosaccharides formation in beverages based on goat\u2019s milk and its permeate

Dorota Cais-Sokolińska,Łukasz K. Kaczyński,Artur Szwengiel

doi:10.1007/s10068-019-00600-0

Dorota Cais-Sokolińska, Łukasz K. Kaczyński + Show 1 more

Open Access

https://doi.org/10.1007/s10068-019-00600-0

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Abstract

The aim of this work was the analysis of galactooligosaccharides (GOS) formation in a model mixture of goat’s milk and its permeate from microfiltration and further concentration by ultrafiltration based on the hydrolysis and transgalactosylation of lactose under various temperature and time regimes. These reactions were catalyzed by a β-galactosidase from Kluyveromyces lactis. Simultaneous hydrolysis and transgalactosylation of the milk lactose was carried out at 37, 40, and 43 °C for 6 h. The maximum GOS content in the mixture was obtained at 37 °C after 20 min. It was 6.9% of the total sugars and the degree of lactose hydrolysis was 13.3%. This was about 10% more GOS than in milk. The mixture containing GOS had a faster maximum acidification rate, 33% greater than before transgalactosylation.

Highlights

Goat’s milk, due to its unique characteristics is of particular interest to consumers and producers and can be the basis for the creation of new dairy products using enzymatic processes and membrane separation (Cais-Sokolinska et al, 2015; Pikul et al, 2014)
The aim of this work was the analysis of galactooligosaccharides (GOS) formation in a model mixture of goat’s milk and its permeate from microfiltration and further concentration by ultrafiltration based on the hydrolysis and transgalactosylation of lactose under various temperature and time regimes
Milk permeate can be subjected to the same technological processes as milk, e.g. lactose hydrolysis, which leads to a further reduction in the lactose content of the finished product

Summary

Introduction

Goat’s milk, due to its unique characteristics is of particular interest to consumers and producers and can be the basis for the creation of new dairy products using enzymatic processes and membrane separation (Cais-Sokolinska et al, 2015; Pikul et al, 2014). Lactose in milk may be a substrate in multidimensional chemistries, including hydrolysis, fructosyl transfer, transgalactosylation, isomerization, oxidation, and reduction. Such processes may involve glucose, galactose, lactosucrose, galactooligosaccharides (GOS), lactulose, lactobionic acid, and lactic acid (Santibanez et al, 2016). GOS are complex mixtures consisting of galactose and glucose, with a molecular (Gal)n–Glu structure. They belong to so-called prebiotics, which are non-digestible and show many beneficial functions in the human body (Cordova et al, 2017). GOS after the transgalactosylation process consist of oligosaccharides with varying degrees of polymerization, significant amounts of monosaccharides (glucose and galactose) and unreacted lactose. The removal of sugar compounds (monosaccharides and lactose) from raw GOS is a fundamental requirement for the introduction of GOS into functional foods (Cordova et al, 2017; Maischberger et al, 2008)

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