Preparation of whey protein hydrolysates using a single- and two-stage enzymatic membrane reactor and their immunological and antioxidant properties: characterization by multivariate data analysis.
An initial 5% (w/v), followed thereafter with replacement aliquots of 3% (w/v), whey protein isolate (WPI) (ca. 86.98% Kjeldahl N x 6.38), was hydrolyzed using Protease N Amano G (IUB 3.4.24.28, Bacillus subtilis) in an enzymatic membrane reactor (EMR) fitted with either a 10 or 3 kDa nominal molecular weight cutoff (NMWCO) tangential flow filter (TFF) membrane. The hydrolysates were desalted by adsorption onto a styrene-based macroporous adsorption resin (MAR) and washed with deionized water to remove the alkali, and the peptides were desorbed with 25, 50, and 95% (v/v) ethyl alcohol. The desalted hydrolysates were analyzed for antibody binding, free radical scavenging, and molecular mass analysis as well as total and free amino acids (FAA). For the first time a quantity called IC50, the concentration of peptides causing 50% inhibition of the available antibody, is introduced to quantify inhibition enzyme-linked immunosorbent assay (ELISA) properties. Principal component analysis (PCA) was used for data reduction. The hydrolysate molecular mass provided the most prominent influence (PC1 = 57.35%), followed by inhibition ELISA (PC2 = 18.90%) and the antioxidant properties (PC3 = 10.43%). Ash was significantly reduced in the desalted fractions; the protein adsorption recoveries were high, whereas desorption with alcohol was prominently influenced by the hydrophobic/ hydrophilic amino acid balance. After hydrolysis, some hydrolysates showed increased ELISA reactivity compared with the native WPI.
Cheison
Seronei Chelulei
SC
School of Public Health and Community Development, Maseno University, P.O. Box 333, Maseno 40105, Kenya. seronei.cheison@wzw.tum.de
Wang
Zhang
Z
Xu
Shi-Ying
SY
D000704:Analysis of Variance; D000975:Antioxidants / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D006868:Hydrolysis; D008894:Milk Proteins / Q000737:chemistry* / Q000276:immunology* / Q000494:pharmacology; D011492:Protein Hydrolysates / Q000737:chemistry*; D000067816:Whey Proteins
D000975:Antioxidants; D008894:Milk Proteins; D011492:Protein Hydrolysates; D000067816:Whey Proteins