Whey proteins are relevant dairy derived products specially for the supply of high-quality protein and may relevant to reduce frailty in older adults, usually associated to low protein intake. Furthermore, whey proteins may be an important source of peptides bioactive (BPs) from food. β-lactoglobulin (β-LG) is the main protein in whey, accounting to around 80 % of the total protein content, however, β-LG is not fully digested and may, for some people, lead to an allergic response. Non-thermal processing technologies like UV-C and PEF are growing in interest for food industries to overcome the chemical changes induced by the traditional thermal processing methods like LTST pasteurization as used to reduce foodborne pathogens. UV-C light irradiation of β-LG has been shown to induce slight changes in the protein conformation due to the presence of the photoactive triads (Trp/Cys-Cys or Tyr/Cys-Cys) which led to disulfide reduction [1]. In this context, the present work investigates the effects of the UV-C light irradiation on the degree of hydrolysis (DH) by trypsin, changes in the peptidomic profile as determined by MALDI-TOF/TOF-MS, and the effect on the hydrolysates transepithelial transport across Caco-2 cell monolayers. β-LG (2 mg per ml) was photolyzed with Io = 1,81.10-10 Einstein/s for 2 hours or for comparison pasteurized by LTLT process. Native protein, UV-C irradiated, and thermo treated β-LG was afterword submitted to trypsin hydrolysis for different times up top 2 hours [2]. Different digestion times were evaluated for DH and the 2-hours hydrolysate submitted to peptidomic analysis and used to evaluate the transepithelial transport across Caco-2 cell monolayers using a static trans-well model [3]. The DH showed significant differences in digestibility for native, UV-C irradiated and thermal processed protein. UV-C light irradiated β-LG showed an increase of 3% in the DH in comparison to the native protein and an increase of almost 6% in comparison to pasteurization. The peptidomic profile as obtained by MALDI-TOF/TOF-MS shows a higher yield of bioactive peptides like the peptide ALPMHIR f(158-164) with a 4-fold increase in comparison to the native protein. The transwell assay suggested that three bioactive peptides fβ-LG (158-164; 87-91 and 57-76), are efficiently transported across Caco-2 cell monolayers with high apparent permeability. Thus, the use of UV-C as non-thermal processing technology for whey protein is a relevant alternative to thermal processing, being able to efficiently reduce foodborne pathogens and also increasing the total hydrolysis capacity by 2% and the specific hydrolysis capacity by 18% for β-LG, and in addition, increasing significantly the yield of bioactive peptides in hydrolysates by the use of commercial proteases.
[1] Fracola, J. S., Processamento. UV-C de proteínas do soro do leite: Efeitos na estrutura e digestibilidade, USP; [2] Cheison, S. et al., Food chemistry, 2011, v.125, 121-127; [3] de Haan, P. et al., Scientific Reports, 2021, v11 (1), 1-13.