Thermal pre-treatment of β-Lactoglobulin as a tool to steer enzymatic hydrolysis and control the release of peptides

Abstract

Tryptic hydrolysis of β-Lactoglobulin (β-Lg) has been shown as an excellent way to produce several functional peptides. However enzymatic hydrolysis results in a mixture of numerous different peptides, which is problematic regarding the enrichment of one functional peptide in foods. Therefore, a new approach was investigated to control enzymatic hydrolysis by thermal pre-treatment of the substrate to produce specifically desired peptides. For this a 5% β-Lg solution (w/w) was denatured at 80°C and the influence of the surrounding pH (pH 4.6, 6.8 and 8) on the formed denatured particles was characterised by degree of denaturation (DD) and particle size. The native, as well as the denatured protein was then hydrolysed by trypsin (EC 3.4.21.4) at enzyme optimal conditions (pH 8 and 37°C). Hydrolysis was monitored by degree of hydrolysis (DH) using the pH-stat method and the hydrolysates were analysed by MALDI-TOF-MS/MS after several DHs. It could be demonstrated that the attacked cleavage sites during tryptic hydrolysis of native β-Lg followed no specific order. Denaturation independent of the environmental conditions led to a decrease of the DH during the total hydrolysis. Of special interest was the formation of non-native monomers by thermal denaturation at pH 8 and the subsequent decrease of attacked peptide bonds to only five different cleavage sites after a DH of 1%. This conditions were favorable, due to the release of a slightly heterogeneous hydrolysate, containing the functional peptide f(142-148), with reported ACE-inhibitory activity.

Substantial Improvement of Tryptic and Chymotryptic Hydrolysis of β-Lactoglobulin Pretreated with High Voltage Electrical Treatments

“…For the tryptic hydrolysis of β-lg samples, (Figure 4A), the DH of the native β-lg reached its maximum (5.6%) after 150 min of hydrolysis, which conforms with the results of Mikhaylin et al, 13 Leeb et al, 2 and Lung et al 49 It is worth noting that trypsin as well as other gastric proteases (e.g., pepsin, chymotrypsin) seems to have a limited ability to hydrolyze β-lg due to its inhibition by enzyme−peptide interactions. 50 Comparing the tryptic hydrolysis of native and preheated β-lg, one can notice that the preheated sample has a 22% higher DH value.…”

“…Their applications in different food products have become increasingly interesting for the agri-food industries. 2 Several authors have defined bioactive peptides as specific fragments of proteins that have a positive impact on human health. 3−5 Milk proteins, such as β-lactoglobulin (major whey protein), are an important source of bioactive peptides.…”

Changes in Nutrient Profile and Antioxidant Activities of Different Fish Soups, Before and After Simulated Gastrointestinal Digestion

“…Furthermore, the biological activity of food is further enhanced by the release of bioactive compounds and peptides during the digestive procedure, thermal pre-treatment, microbial fermentation or other technological processing [ 12 ]. Studies of the pharmacological effects of fish peptides or the other metabolites hydrolyzed by digestion have revealed their different functions, such as antihypertensive, immunomodulatory, antioxidant, antitumor, and antimicrobial activities [ 13 ].…”

Whey protein isolate polydispersity affects enzymatic hydrolysis outcomes

“…The nature of this denaturation and the characteristics of any resulting aggregates will dictate the alteration of the reaction. For example, the pH, mineral content and heterogeneity of the substrate during heat-treatment will determine the size of any resulting aggregates and whether that matrix restricts or facilitates enzymatic cleavage (Leeb, Kulozik & Cheison, 2011;O'Loughlin et al, 2012).…”