Extraction, Purification and Thermodynamic Characterization of Almond (Amygdalus communis) β-Galactosidase for the Preparation of Delactosed Milk

Ajay Pal1*, Melita Lobo2 and Farhath Khanum2

1Department of Biochemistry, College of Basic Sciences and Humanities, Chaudhary Charan Singh Haryana Agricultural University, Hisar–125004, India

2Biochemistry and Nutrition Discipline, Defence Food Research Laboratory, Siddarthanagar, Mysore–570011, India

Article history:

Received April 22, 2011
Accepted September 24, 2012

Key words:

almond, β-galactosidase extraction, lactose intolerance, thermodynamic characterization


Buffer type, pH and ionic strength, as well as the fraction of polyvinylpyrrolidone were optimized for efficient extraction of β-galactosidase from almond seeds. The enzyme was purified up to electrophoretic homogeneity employing (NH4)2SO4 (15–60 %) fractionation, size exclusion and ion-exchange chromatography. Molecular mass of β-galactosidase as estimated by gel filtration and SDS-PAGE was approx. 62 kDa, confirming its monomeric nature. The optimum activity of the enzyme was at pH=5.5, and it was stable within the range of pH=5.0–6.0. Various kinetic parameters of β-galactosidase thermal inactivation were calculated: ΔH°, ΔS° and ΔG° suggested that the enzyme undergoes significant processes of unfolding during denaturation. Using b-galactosidase from almond seed powder, lactose hydrolysis in milk up to approx. 50 % was observed. The findings indicate the potential use of almond seeds for the production of low/delactosed milk for lactose-intolerant population. 

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