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

Ajay Pal^1*, Melita Lobo² and Farhath Khanum<sup>2

1</sup>Department 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

Summary:                                                                                                                                                                                 
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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