Physico-chemical changes in caseins and micellar casein isolate induced by ultraviolet-C light and pulsed electrical field

Research output: Book/ReportPh.D. thesis

  • Aline Teixeira Do Brasil Morais
Dairy products are defined as functional foods that contain proteins, fats, sugars, vitamins, and minerals such as calcium and phosphate. Although they are present in the daily diet of most of the population, children under 2 years of age and older adults commonly develop an allergic response to milk proteins, reducing the uptake of important nutrients such as proteins essential for maintaining mental and bone health and important for building muscle mass. Caseins comprise 80% of total milk protein and are the most allergenic protein due to the sequence of IgE epitopes and the type of processing in the food industry. During digestion, casein hydrolysis releases bioactive peptides, specially β-casomorphins, peptides with opioid activity that trigger allergic processes causing inflammation in the intestine. From this perspective, this work aimed to investigate the physico-chemical modifications in caseins and micellar casein isolates after nonthermal treatments, by UV-C light and pulsed electric field, PEF. Furthermore, evaluate the peptides of released impact on the peptide profile, by simulating in vitro gastric digestion and the uptake through caco-2 cells, as a model of intestine epithelium cells. Micellar casein showed a reduction in particle size (p<0.05), after 15 minutes of light exposure, from 138.1 to 96.0 nm. In the opposite direction, thermal treatment, LTLT, generated large micellar aggregates, as seen with increasing particle size to 159.8 nm (p<0.05) and micelle surface in AFM images. Structural modifications were observed in samples pretreated with UV-C light by decreasing the intensity of aromatic amino acids such as tyrosine and tryptophan, which are important in maintaining the conformation of the proteins. The slight modifications induced in micellar caseins by exposure to light did not affect the production of peptides or the absorption experiments. The treatment with PEF resulted in different effects; under the RT condition, there was a thermal effect due to the formation of micelle aggregates by increasing the roughness of the micelle surface. Under CT conditions, the electrical effect was observed by a reduction in the particle size, and the slight modifications in the micelle structure at Raman scattering suggest spatial reorganization in the micelle conformation. Furthermore, micellar casein PEF treated with CT showed an improvement in the number of peptides released from gastric digestion, but with lower uptake even after 90 minutes of transport assay. In conclusion, both treatments, UV-C and PEF, have proven promising as nonthermal alternatives to enhance nutritional properties in dairy products in the food industry by promoting the release of bioactive peptides that could provide the uptake of impaired nutrients in the elderly population.
Original languageEnglish
PublisherDepartment of Food Science, Faculty of Science, University of Copenhagen
Number of pages117
Publication statusPublished - 2022

ID: 337596200