Modeling and optimization of enzymatic and fermentation reactions in the production process of a symbiotic fermented milk beverage

Abstract

Symbiotic fermented kinds of milk are products with probiotic microorganisms and a simultaneous prebiotic effect. The presence of fibers or oligosaccharides causes it. This work aimed to evaluate and model fermented milk beverage production with probiotic microorganisms and in situ Galactooligosaccharides (GOS) synthesis. GOS enzymatic production was maximized through the mathematical model, and finally, the mathematical prediction was experimentally validated. For this purpose, the enzymatic kinetics of GOS production from Aspergillus oryzae β-galactosidase enzyme was experimentally evaluated for different initial lactose concentrations (30%, 35%, and 40% w/v) and enzyme/lactose ratio (R: 0.2%, 0.4%, and 0.6%). In addition, the fermentative kinetics of lactic acid and biomass production were evaluated using the probiotic strain Lactobacillus acidophilus. The parameters correlation for both models was then performed. A unified model determined the process conditions that maximize GOS concentration in the fermented milk beverage. According to the model, the operating values that maximized the GOS production were 40% of initial lactose, R: 0.15%, 20 min of enzymatic reaction, and 17 h of fermentative reaction. The final fermented milk drink showed a GOS content of 2.9 g/portion of 200 g, guaranteeing the recommended daily values of the prebiotic with the consumption of two servings.

Keywords:
Galactooligosaccharides; Enzyme kinetics; Fermentation kinetics; Fermented milk drink; β-galactosidase

HIGHLIGHTS

An enzymatic reaction in the first part of the symbiotic milk beverage process generated galactooligosaccharides

Enzymatic product rich in Galactooligosaccharides is part of the substrate of the fermentation reaction to produce the symbiotic milk beverage

Fermented milk beverages could be classified as prebiotic beverages according to their galactooligosaccharide content