Enzymatic generation of lactulose in sweet and acid whey: Feasibility study for the scale up towards robust processing

• Published in: Food and bioproducts processing Vol. 119; pp. 329 - 336
• Main Authors: Schmidt, Christian M., Nedele, Ann-Kathrin, Hinrichs, Jörg
• Format: Journal Article
• Language: English
• Published: Rugby Elsevier B.V 01.01.2020; Elsevier Science Ltd
• Subjects: Dairy; Enzymes; Feasibility studies; Galactosidase; Lactase; Lactose; Lactulose; Microbial origin; Prebiotic; Prebiotics; Proteins; Ratios; Robustness; Scaling up; Transgalactosylation; Valorization; Whey; Yeasts; Yields; β-galactosidase; Dairy; β-galactosidase; Microbial origin; Transgalactosylation; Prebiotic; Valorization
• ISSN: 0960-3085; 1744-3571
• DOI: 10.1016/j.fbp.2019.11.015

•Seven β-galactosidases were tested on their ability to produce lactulose in whey.•Influence of pH value on hydrolysis and transgalactosylation was investigated.•Enzymes with sufficient yield in pH-ranges relevant for whey were identified. Utilization of sweet and acid whey is a frequently researched and discussed topic, but lactose as major part of the dry mater is often neglected. Hence, the aim of this study was to valorize the non-protein fraction of sweet and acid whey by transgalactosylation of lactose to prebiotic lactulose. Therefore, seven commercial β-galactosidases were tested regarding their ability to produce lactulose in sweet and acid whey UF-permeates. Additional performance parameters characterizing the transgalactosylation reaction were defined and evaluated in order to select enzyme preparations. Three promising enzyme preparations were identified, which provide a high lactulose yield (Enzeco: 0.27, Biolactase: 0.21, Lactozym: 0.21). Furthermore, the high yield was stable over a long period of time (≥24h) and therefore, qualifies for a scale up towards robust processing. The degree of hydrolysis exceeded 0.8 only with the bacterial enzyme preparations (Saphera, Nola-Fit), which showed no affinity towards the transgalactosylation reaction. Yeast β-galactosidases (Ha-Lactase, Biolactase, Lactozym) provided overall higher isomeric ratios of 1-lactulose, compared to fungal β-galactosidases (Enzeco, Maxilact).