Characterisation of peptide molecular mass distribution in commercial hydrolysates and hydrolysate-based nutritional products

High performance size exclusion chromatography with UV detection (HPSEC/UV) was evaluated for the routine characterisation of peptide molecular mass distributions in commercial protein hydrolysates and in protein hydrolysate-based liquid nutritional products. Several known sources of quantitative error were examined, as were additional sources potentially introduced by the complex matrices of liquid nutritional products. Although it is clear that these sources may compromise the accuracy of the molecular mass distribution estimates, the magnitude was typically small, and did not detract appreciably from method applicability. Method capability for reliably discriminating different lots of the same hydrolysate commodity was established via median molecular mass determinations. The molecular mass profiles of liquid nutritional products (median molecular mass range = 300–3610 Da) agreed well with those of their protein hydrolysate ingredient: the median molecular mass ratios for nutritional product to hydrolysate ingredient averaged 0.984 ± 0.091 (n = 5). The study demonstrated the considerable utility of the HPSEC/UV method as a direct, informative, simple, precise, rugged, and relatively inexpensive means for the routine characterisation of peptide molecular mass distributions in commercial protein hydrolysates and in hydrolysate-based liquid nutritional products.