Sustainable Electroisomerization of Lactose into Lactulose and Comparison with the Chemical Isomerization at Equivalent Solution Alkalinity

Abstract

The demand of lactulose production is increasing tremendously because of its bifidogenic (prebiotic) functionality. Therefore, the isomerization of lactose to synthesize lactulose through electroactivation (EA) technology is of great interest nowadays. However, lactulose production through electroisomerization is affected by several operational and experimental conditions, and the process needs to be optimized. In this context, the EA technique was applied to isomerize lactose into lactulose in an EA reactor modulated by anion and cation exchange membranes. The effect of lactose concentrations (5, 10, 15, and 20%), applied electric fields (300, 600, and 900 mA), and processing time (0−60 min) on lactose electroisomerization rate (lactulose formation) and coproduct (glucose, galactose, and fructose) formation has been investigated. The effect of different physicochemical parameters such as pH, alkalinity, temperature, ion migration, and oxidation−reduction potential (ORP) on the conversion of lactose into lactulose was correlated with the lactulose formation to understand the involved process mechanism of action. The conversion of lactose into lactulose was lactose-concentration-, electric-current-, and EA-time-dependent and reached the highest lactulose yield of 38% at 40 min using a 900 mA current intensity in a 10% lactose solution. The results were then compared to conventional chemical isomerization maintaining similar alkaline conditions at ambient temperature (22 ± 2 °C). A higher yield of lactulose was achieved in the EA process within a short reaction time compared to that of the chemical isomerization. The outcome of this study suggests that EA is a promising technique for the enhanced production of lactulose from lactose.

The Mucosally-Adherent Rectal Microbiota Contains Features Unique to Alcohol-Related Cirrhosis

“…All of our patients are from the Northeastern United States and thus likely consuming similar American diets. However, given the higher prevalence of lactase-persistence in people of Scandinavian descent 48 and the biochemical and structural similarity between lactose and lactulose, 49 Caucasian subjects are more likely to tolerate lactose and remain on lactulose, whereas non-Caucasian subjects may have higher prevalence of intolerance to lactose and lactulose. Indeed, no non-Caucasian subjects in the alcohol-related cirrhosis group were on lactulose despite some having documented hepatic encephalopathy.…”

Sustainable Valorization of Whey by Electroactivation Technology for In Situ Isomerization of Lactose into Lactulose: Comparison between Electroactivation and Chemical Processes at Equivalent Solution Alkalinity

“…In fact, H + and OH − ions might be generated by water decomposition at the CEM interface facing the central compartment once the reaction reached a critical stage, to evade the ion deficiency in the central compartment. 19 Maximum alkalinities of 1.33, 16.00, and 25.33 mmol/L were obtained at 60 min of EA under 300, 600, and 900 mA current intensities, respectively, when a 14% whey solution was used. On the other hand, only 3.33 and 5.33 mmol/L alkalinities were obtained for 600 and 900 mA current intensities, respectively, and no alkalinity was created for 300 mA in the 21% whey solution.…”

“…In fact, more H + and OH − ions were produced through this water splitting, and newly generated H + ions competed for electromigration with K + ions. 19 The competition for electromigration from the central compartment toward the cathodic one was favorable for the H + ions because H + ion has higher electrophoretic mobility than K + ion in solution. As a result, the K + cation migration toward the catholyte also decreased at the same time.…”

“…21 Another possible reason could be the decreased conductivity in the central compartment because the demineralization due to ion migration may have increased the resistance of the system. 19 The rate of temperature increase was higher for greater current intensities used because the heated energy dissipation is proportional to the increase in the electric tension and electric current (Joule's law). 17 Nevertheless, the statistical analysis of the obtained data did not show any correlation between the temperature rise (from 22 to 42 °C) and the formed lactulose.…”

“…However, in our previous study, it was found that lactulose can be produced without external heating with a high pH (>10.00). 19 It is worth mentioning that all of the above-mentioned reports used lactose as feed solution, whereas whey was used in our study. Thus, it is obvious that higher activation energy was required for the isomerization reaction for whey than for lactose because it contains proteins, peptides, and other components with high buffering capacity.…”