Enzymatic hydrolysis of lupin protein isolates-Changes in the molecular weight distribution, technofunctional characteristics, and sensory attributes.

Katharina Schlegel,Andrea Hickisch,Ali Abas Wani,Ute Schweiggert‐Weisz,Peter Eisner,Katharina Sontheimer

doi:10.1002/fsn3.1139

Abstract

Enzymatic hydrolysis of lupin protein isolates (LPI; Lupinus angustifolius L.) was performed with nine different protease preparations to investigate their effect on technofunctionality, sensory properties, and the integrity of the proteins to estimate the reduction of the immunoreactivity. Alcalase 2.4 L, papain, and pepsin were most effective in the degradation of the α‐ and β‐conglutin examined by SDS–PAGE analysis, although the degree of hydrolysis only slightly increased. The technofunctional properties of LPI—solubility, emulsifying, and foaming activity—were improved by most of the proteolytic enzymes with the most impressive increase from 980% foam activity for LPI up to 3,614% foam activity for pepsin hydrolysate. The formation of bitterness, most likely linked to generation of bitter peptides, was pronounced in the Alcalase hydrolysate, while the other hydrolysates did not show an extensive increase in bitterness compared to the LPI. Other sensory attributes of the hydrolysates—with the exception of Alcalase treatment—were also very similar to the LPI. The results of this study show the potential of enzymatic degradation of LPI to modify the IgE‐reacting polypeptides and to improve the technofunctionality of the isolates and therefore their use as food ingredients.

Highlights

The demand for high‐quality plant proteins for applications in the food and feed sectors is increasing, and the search for alternative proteins has expanded considerably in the last years
Enzymatic hydrolysis of lupin protein isolates (LPI; Lupinus angustifolius L.) was performed with nine different protease preparations to investigate their effect on technofunctionality, sensory properties, and the integrity of the proteins to estimate the reduction of the immunoreactivity
The aim of this study was to investigate the effect of enzymatic hydrolysis using different proteases on the integrity of the proteins of LPI by means of degree of hydrolysis (DH) and molecular weight distribution, their technofunctionality and sensory properties

Summary

Introduction

The demand for high‐quality plant proteins for applications in the food and feed sectors is increasing, and the search for alternative proteins has expanded considerably in the last years. The protein content within lupin seeds can vary with 31% amounts in Lupinus angustifolius L. up to 44% in Lupinus luteus. The most abundant storage proteins in lupin seeds are the globulins, which comprise two major protein types, β‐conglutin (7S globulin, vicilin‐like protein) and α‐conglutin (11S globulin, legumin‐like protein) and minor components, γ‐conglutin and δ‐conglutin (Duranti et al, 1981). Β‐Conglutin is known as a major allergen The prevalence of sensitization and allergenic reaction is less known in the general population and as lupin becomes more popular as an alternative protein source for human consumption, the increased demand for the proteins may expose more consumers to lupin antigens (Jimenez‐Lopez et al, 2018). The known cases of lupin allergies have mainly been reported in patients with allergies to other legumes such as soybean, pea, lentil, chickpea, and peanut (Jappe & Vieths, 2010), probably due to cross‐reactions to structurally similar proteins including similar epitope regions from other legume species (Jimenez‐Lopez et al, 2018)

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