Simultaneous enzymatic hydrolysis and lactic fermentation to obtain a yogurt with low lactose content

André Rosa Martins,Janaína Fernandes De Medeiros Burkert,Ricardo Lemos Monteiro,Carlos André Veiga Burkert

doi:10.1590/s1413-70542012000500008

Abstract

In a single-stage process with the simultaneous addition of β-galactosidase and lactic culture, the lactose conversion, the processing time, viscosity and syneresis were evaluated. Fermentation was promoted by lactic culture containing two probiotic microorganisms, Bifidobacterium animalis and Lactobacillus acidophilus, associated with the typical microorganisms of yogurt. An enzymatic preparation containing β-galactosidases from Kluyveromyces lactis and Aspergillus niger was used. A central composite design (2³ trials plus three central points) was proposed in order to evaluate the effects of initial lactose concentration, enzyme concentration and the time of addition of the enzyme. The following conditions were established: initial lactose concentration of 91 g L-1, enzyme concentration of 0.5 g L-1 and enzyme addition at the beginning of fermentation. In these conditions, a decrease in processing time (from 4.55 to 3.68 h) and an increase in lactose conversion (from 15.2 to 97.9%) were observed in relation to the fermentation without enzyme addition, and no detrimental changes in some physical properties of yogurt (viscosity, and syneresis).

Highlights

Lactose intolerance affects a significant proportion of the worldwide adult population, with a major impact on the Asian, African, Amerindian and Aboriginal communities, with levels that may exceed 90% (SCHAAFSMA, 2008; SWALLOW, 2003).Lactose intolerance can be due to genetic factors
In a single-stage process with simultaneous exogenous b-galactosidase action and lactic fermentation, a 23 Central Composite Design (CCD) with three central points was proposed, resulting in a total of 11 trials (Table 2) in order to evaluate the effects of initial lactose concentration (L ), enzyme concentration (E) and the time of addition of the enzyme (t) on the parameters of processing time, viscosity, syneresis and lactose conversion
The results indicate a low lactose conversion for the fermentation without enzyme, similar to that observed by Lamoureux, Roy and Gauthier (2002)

Summary

Introduction

Lactose intolerance can be due to genetic factors. A single threshold of lactose for all lactose intolerant subjects cannot be determined owing to the great variation in individual tolerances. Symptons of lactose intolerance have been described after intake of less than 6 g of lactose in some subjects, and the only satisfactory treatment of lactose intolerance is a diet with reduced lactose content (EUROPEAN FOOD SAFETYAUTHORITY-EFSA, 2010). Β -galactosidase (EC 3.2.1.23) is an enzyme that catalyses the hydrolysis of lactose to glucose and galactose. It is potentially important in the production of lactose-reduced products in the food and dairy industry

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Results