Kinetic modeling of lactose hydrolysis with an immobilized beta-galactosidase from Kluyveromyces fragilis

Bio-conversion of whey lactose using enzymatic hydrolysis with β-galactosidase: an experimental and kinetic study

Lactose in cheese whey is increasingly challenging to metabolise under normal conditions. The hydrolysis of whey lactose into glucose and galactose using enzymatic methods has been acclaimed to confer benefits like enhanced substrate availability for better degradation in anaerobic digestion. In the present study, whey lactose was subjected to hydrolysis using the enzyme β-galactosidase derived from Aspergillus oryzae fungus to reduce the difficulty of lipid and fat transformation in anaerobic digestion. The individual and combined effects of hydrolysis parameters, pH, enzyme load, reaction time and temperature were studied using Response Surface Methodology by Central Composite Design. The optimum conditions were determined based on variance analyses and surface plots; pH 4.63, temperature 40.47°C, reaction time 25.96 min and enzyme load 0.49%. Results showed a maximum lactose hydrolysis value of 86.21%, while the predicted value was 87.44%. Indeed, enzyme hydrolysis induced a change of soluble chemical oxygen demand around 24.6% and 75.8% reduction in volatile fatty acid concentration. Upon anaerobic digestion, the pre-hydrolysed whey revealed a 3.6-fold higher bio-methane production than that of raw hey, and a visible decrease in volatile fatty acid concentrations. The resultant data agreed with the Gompertz model, and lag phase times were significantly reduced for hydrolysed whey.

A Review on Psychrophilic β-D-Galactosidases and Their Potential Applications

The majority of the Earth's ecosystem is frigid and frozen, which permits a vast range of microbial life forms to thrive by triggering physiological responses that allow them to survive in cold and frozen settings. The apparent biotechnology value of these cold-adapted enzymes has been targeted. Enzymes' market size was around USD 6.3 billion in 2017 and will witness growth at around 6.8% CAGR up to 2024 owing to shifting consumer preferences towards packaged and processed foods due to the rising awareness pertaining to food safety and security reported by Global Market Insights (Report ID-GMI 743). Various firms are looking for innovative psychrophilic enzymes in order to construct more effective biochemical pathways with shorter reaction times, use less energy, and are ecologically acceptable. D-Galactosidase catalyzes the hydrolysis of the glycosidic oxygen link between the terminal non-reducing D-galactoside unit and the glycoside molecule. At refrigerated temperature, the stable structure of psychrophile enzymes adjusts for the reduced kinetic energy. It may be beneficial in a wide variety of activities such as pasteurization of food, conversion of biomass, biological role of biomolecules, ambient biosensors, and phytoremediation. Recently, psychrophile enzymes are also used in claning the contact lens. β-D-Galactosidases have been identified and extracted from yeasts, fungi, bacteria, and plants. Conventional (hydrolyzing activity) and nonconventional (non-hydrolytic activity) applications are available for these enzymes due to its transgalactosylation activity which produce high value-added oligosaccharides. This review content will offer new perspectives on cold-active β-galactosidases, their source, structure, stability, and application.

Challenges and perspectives of the β-galactosidase enzyme

The enzyme β-galactosidase has great potential for application in the food and pharmaceutical industries due to its ability to perform the hydrolysis of lactose, a disaccharide present in milk and in dairy by-products. It can be used in free form, in batch processes, or in immobilized form, which allows continuous operation and provides greater enzymatic stability. The choice of method and support for enzyme immobilization is essential, as the performance of the biocatalyst is strongly influenced by the properties of the material used and by the interaction mechanisms between support and enzyme. Therefore, this review showed the main enzyme immobilization techniques, and the most used supports for the constitution of biocatalysts. Also, materials with the potential for immobilization of β-galactosidases and the importance of their biotechnological application are presented. KEY POINTS: • The main methods of immobilization are physical adsorption, covalent bonding, and crosslinking. • The structural conditions of the supports are determining factors in the performance of the biocatalysts. • Enzymatic hydrolysis plays an important role in the biotechnology industry.

Encapsulated NOLA™ Fit 5500 Lactase—An Economically Beneficial Way to Obtain Lactose-Free Milk at Low Temperature

The current requirements of industrial biocatalysis are related to economically beneficial and environmentally friendly processes. Such a strategy engages low-temperature reactions. The presented approach is essential, especially in food processes, where temperature affects the quality and nutritional value foodstuffs. The subject of the study is the hydrolysis of lactose with the commercial lactase NOLA™ Fit 5500 (NOLA). The complete decomposition of lactose into two monosaccharides gives a sweeter product, recommended for lactose intolerant people and those controlling a product’s caloric content. The hydrolysis reaction was performed at 15 °C, which is related to milk transportation and storage temperature. The enzyme showed activity over the entire range of substrate concentrations (up to 55 g/L lactose). For reusability and easy isolation, the enzyme was encapsulated in a sodium alginate network. Its stability allows carrying out six cycles of the complete hydrolysis of lactose to monosaccharides, lasting from two to four hours. During the study, the kinetic description of native and encapsulated NOLA was conducted. As a result, the model of competitive galactose inhibition and glucose mixed influence (competitive inhibition and activation) was proposed. The capsule size does not influence the reaction rate; thus, the substrate diffusion into capsules can be omitted from the process description. The prepared 4 mm capsules are easy to separate between cycles, e.g., using sieves.

Synthesis of Ibuprofen Monoglyceride in Solventless Medium with Novozym®435: Kinetic Analysis

This study investigates the enzymatic esterification of glycerol and ibuprofen in a solventless medium catalyzed by immobilized lipase B from Candida antarctica (Novozym®435). Fixing the concentration of this enzymatic solid preparation at 30 g·L−1, and operating at a constant stirring speed of 720 rpm, the temperature was changed between 50 and 80 °C, while the initial concentration of ibuprofen was studied from 20 to 100 g·L−1. Under these conditions, the resistance of external mass transport can be neglected, as confirmed by the Mears criterion (Me < 0.15). However, the mass transfer limitation inside the pores of the support has been evidenced. The values of the effectiveness factor (η) vary between 0.08 and 0.16 for the particle size range considered according to the Weisz–Prater criteria. Preliminary runs permit us to conclude that the enzyme was deactivated at medium to high temperatures and initial concentration values of ibuprofen. Several phenomenological kinetic models were proposed and fitted to all data available, using physical and statistical criteria to select the most adequate model. The best kinetic model was a reversible sigmoidal model with pseudo-first order with respect to dissolved ibuprofen and order 2 with respect to monoester ibuprofen, assuming the total first-order one-step deactivation of the enzyme, with partial first order for ibuprofen and enzyme activity.

Lactose in processed foods: evaluating the availability of information regarding its amount

Patients with lactose intolerance, a high prevalence disease, should control the intake of food with lactose to avoid gastrointestinal symptoms. Since tolerance depends on the amount of lactose ingested, it is essential to discuss the availability of the amount of lactose information in processed foods, which is currently not mandatory. The study measured the availability of information on the amount of lactose on the labels of processed food that contained milk or lactose in the ingredient list. Then, we contacted the food industry to request this information. We evaluated 1,209 processed foods, of which 1,092 were traditional and 117 were diet/light/zero. Only 3,1% of the analyzed foods provided information on the amount of lactose in the labeled nutrition table. This information was more available in the diet/light/zero food group. Furthermore, of the 156 contacted companies, only 14 reported the amount of lactose contained in foods, 93 answered the request, but have not provided the amounts and 49 did not answer the request. We concluded that there is a low availability of information about the amount of lactose in processed foods.

The effect of transmembrane pressure and feed flow rate on transgalactosylation of lactose in an enzymatic membrane reactor

The hydrolysis and transgalactosylation reaction of lactose in enzymatic membrane reactor (EMR) with immobilized β-gal is affected by transmembrane pressure (TMP) and feed flow rate.

Lactose hydrolysis by β-galactosidase enzyme: optimization using response surface methodology

In the present study, it was aimed to optimize the process of lactose hydrolysis using free and immobilized β-galactosidase to produce glucose and galactose. Response surface methodology (RSM) by central composite design (CCD) was employed to optimize the degree of hydrolysis by varying three parameters, temperature (15-45°C), solution pH (5-9) and β-galactosidase enzyme concentration (2-8mg/mL) for free mode of analysis and sodium alginate concentration (2-4%), calcium chloride concentration (3-6%) and enzyme concentration (2-8mg/mL) for immobilized process. Based on plots and variance analysis, the optimum operational conditions for maximizing lactose hydrolysis were found to be temperature (35.5°C), pH (6.7) and enzyme concentration (6.7mg/mL) in free mode and sodium alginate concentration (3%), calcium chloride concentration (5.9%) and enzyme concentration (5.2mg/mL) in immobilized mode.

Potential Applications of Immobilized β-Galactosidase in Food Processing Industries

The enzyme β-galactosidase can be obtained from a wide variety of sources such as microorganisms, plants, and animals. The use of β-galactosidase for the hydrolysis of lactose in milk and whey is one of the promising enzymatic applications in food and dairy processing industries. The enzyme can be used in either soluble or immobilized forms but the soluble enzyme can be used only for batch processes and the immobilized form has the advantage of being used in batch wise as well as in continuous operation. Immobilization has been found to be convenient method to make enzyme thermostable and to prevent the loss of enzyme activity. This review has been focused on the different types of techniques used for the immobilization of β-galactosidase and its potential applications in food industry.

Calcium alginate entrapped preparations of Aspergillus oryzae beta galactosidase: its stability and applications in the hydrolysis of lactose

Insoluble concanavalin A-beta galactosidase complex was obtained by using jack bean extract and this complex was crosslinked with glutaraldehyde, in order to maintain the integrity of complex in the presence of its substrate or products. Concanavalin A-beta galactosidase complex retained 92% of the initial enzyme activity whereas crosslinked complex showed 88% activity. Entrapment of concanavalin A-beta galactosidase complex into calcium alginate beads provided suitability to use this preparation in reactors. Temperature- and pH-optima of the various immobilized beta galactosidase preparations were the same as its soluble counterpart. Entrapped crosslinked concanavalin A-beta galactosidase complex retained more than 50% activity after 1h exposure with 4.0 M urea at room temperature. Moreover, entrapped crosslinked concanavalin A-beta galactosidase complex retained 81 and 62% of the original enzymatic activity in the presence of 5% calcium chloride and 5% galactose, respectively. Entrapped crosslinked concanavalin A-beta galactosidase complex preparation was more superior in the continuous hydrolysis of lactose in a batch process as compared to the other entrapped preparations. This entrapped crosslinked concanavalin A-beta galactosidase complex retained 95% activity after seventh repeated use and 93% of its original activity even after 2 months storage at 4 degrees C.

Kinetic and enzymatic adsorption model in a recirculation hollow-fibre bioreactor

A general procedure has been developed to model the behaviour of enzymatic reactions in a membrane bioreactor. This procedure unifies the kinetics of the reaction and the adsorption of the enzyme or enzymatic complexes on the membrane, enabling the selection of the most appropriate kinetic model. The general procedure proposed has been particularized and applied to experimental results obtained with two enzymatic reactions carried out in a hollow-fibre reactor, enzymatic hydrolysis of lactose by beta-galactosidase and glucose-fructose isomerization by glucose isomerase. The application of the general model has allowed us to determine the mechanism of the reaction for both kinetic reactions, assuming the adsorption of the enzymatic complex EGa for lactose hydrolysis and the adsorption of the free enzyme onto the membrane for glucose-fructose isomerization.