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Contribution to the production of lactulose-rich whey by in situ electro-isomerization of lactose and effect on whey proteins after electro-activation as confirmed by matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry and sodium dodecyl sulfate-polyacrylamide gel electrophoresis

Kareb, Ourdia, Champagne, Claude P., Aïder, Mohammed
Journal of dairy science 2016 v.99 no.4 pp. 2552-2570
antioxidant activity, antioxidants, biotransformation, cheese whey, coproducts, dairy industry, desorption, electric current, free radicals, functional foods, galactose, hydrolysis, ionization, isomerization, lactose, lactulose, manufacturing, matrix-assisted laser desorption-ionization mass spectrometry, polyacrylamide gel electrophoresis, prebiotics, sustainable technology, synergism, temperature, whey, whey protein
Cheese-whey, a major co-product of the dairy industry, has recently been the subject of many technological applications. We studied the bioconversion of whey into valuable bio-products such as a potential lactulose prebiotic and compounds with antioxidant properties. This paper examines efficiency, safety, and economics of electro-activation as an eco-friendly technology for a maximum valorization of whey. Thus, a bottom-up approach was therefore addressed. The effect of 4 experimental parameters—low working temperatures (0, 10, and 25°C), current intensities (400, 600, and 800mA), volume conditions (100, 200, and 300mL), and feed concentrations [7, 14, and 28% (wt/vol)]—on lactose-whey isomerization to lactulose under electro-activation process were studied. Structural characteristics of whey proteins and antioxidant functionality were also investigated. The results showed a compromise to be reached between both parameters. Therefore, the maximum yield of 35% of lactulose was achieved after 40min of reaction at the working temperature of 10°C under 400mA electric current field and 100-mL volume conditions with using feed solution at 7% (wt/vol). The isomerization of lactose to lactulose is accomplished by subsequent degradation to galactose, but only at a very small amount. Additionally, whey electro-activation showed significantly elevated antioxidant capacity compared with the untreated samples. The enhancement of antioxidant functionality of whey electro-activation resulted from the synergistic effect of its partial hydrolysis and the formation of antioxidant components that were able to scavenge free radicals. In conclusion, the findings of this study reveal that the whey treated by the safety electro-activation technology has both lactulose-prebiotic and antioxidant properties and could have a substantial application in the manufacture of pharmaceutical and functional foods.