TY - JOUR
T1 - Simultaneous synthesis of mixtures of lactulose and galacto-oligosaccharides and their selective fermentation
AU - Guerrero, Cecilia
AU - Vera, Carlos
AU - Acevedo, Fernando
AU - Illanes, Andrés
N1 - Funding Information:
Work financed by Fondecyt 1130059 and 3130339 from Conicyt, Chile. We acknowledge the generous donations of A. oryzae β-galactosidase by Enzyme Development Corporation (New York, USA) and the donation of strains of Bifidobacterium lactis, Bifodobacterium longun, Lactobacillus rhamnosus and Lactobacillus platarum by Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), La Plata, Argentina. Valuable contribution of professor Robert Rastall and Dr. Sofia Kolida of the Department of Food and Nutritional Sciences, The University of Reading, UK, both in the development of the experimental work and the preparation of the manuscript, is acknowledged.
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/9/1
Y1 - 2015/9/1
N2 - Lactulose and galacto-oligosaccharides (GOS) are well recognized prebiotics derived from lactose. In the synthesis of lactulose with β-galactosidases GOS are also produced, but the ratio of lactulose and GOS in the product can be tuned at will, depending on the operation conditions, so to obtain an optimal product distribution in terms of prebiotic potential. The selectivity of fermentation of each carbohydrate alone as well as mixtures of both was determined using pH-controlled anaerobic batch cultures with faecal inoculum. Within the experimental range considered, lactulose/GOS molar ratio of 4 resulted in the highest selectivity for Bifidobacterium and Lactobacillus/Enterococcus, so this ratio was selected as the target for the synthesis of lactulose from fructose and lactose with Aspergillus oryzae β-galactosidase. Synthesis was optimized using response surface methodology, considering temperature, initial concentrations of acceptor sugars and fructose/lactose molar ratio as key variables, with the aim of maximizing lactulose yield at the optimal product distribution in terms of prebiotic potential (lactulose/GOS molar ratio of 4). Under optimal conditions (50. °C, 50%w/w total initial concentrations of sugars and fructose/lactose molar ratio of 6.44), lactulose yield of 0.26. g of lactulose produced per g of initial lactose was obtained at the optimal product distribution.
AB - Lactulose and galacto-oligosaccharides (GOS) are well recognized prebiotics derived from lactose. In the synthesis of lactulose with β-galactosidases GOS are also produced, but the ratio of lactulose and GOS in the product can be tuned at will, depending on the operation conditions, so to obtain an optimal product distribution in terms of prebiotic potential. The selectivity of fermentation of each carbohydrate alone as well as mixtures of both was determined using pH-controlled anaerobic batch cultures with faecal inoculum. Within the experimental range considered, lactulose/GOS molar ratio of 4 resulted in the highest selectivity for Bifidobacterium and Lactobacillus/Enterococcus, so this ratio was selected as the target for the synthesis of lactulose from fructose and lactose with Aspergillus oryzae β-galactosidase. Synthesis was optimized using response surface methodology, considering temperature, initial concentrations of acceptor sugars and fructose/lactose molar ratio as key variables, with the aim of maximizing lactulose yield at the optimal product distribution in terms of prebiotic potential (lactulose/GOS molar ratio of 4). Under optimal conditions (50. °C, 50%w/w total initial concentrations of sugars and fructose/lactose molar ratio of 6.44), lactulose yield of 0.26. g of lactulose produced per g of initial lactose was obtained at the optimal product distribution.
KW - Galacto-oligosaccharides
KW - Lactulose
KW - Prebiotics
KW - Probiotics
KW - β-galactosidase
UR - http://www.scopus.com/inward/record.url?scp=84934999423&partnerID=8YFLogxK
U2 - 10.1016/j.jbiotec.2015.06.394
DO - 10.1016/j.jbiotec.2015.06.394
M3 - Article
C2 - 26080080
AN - SCOPUS:84934999423
VL - 209
SP - 31
EP - 40
JO - Journal of Biotechnology
JF - Journal of Biotechnology
SN - 0168-1656
ER -