Heat-induced changes in microstructure of spray-dried plant protein isolates and its implications on in vitro gastric digestion. (January 2020)

• Record Type: Journal Article
• Authors: Rivera del Rio, Andrea; Opazo-Navarrete, Mauricio; Cepero-Betancourt, Yamira; Tabilo-Munizaga, Gipsy; Boom, Remko M.; Janssen, Anja E.M.
• Is Part Of: Lebensmittel-Wissenschaft + Technologie =. Volume 118(2020)
• Publication Date: 2020-01
• Subjects: In vitro digestion -- Gastric digestion -- Protein digestibility -- Spray-dried protein isolates -- Soy protein isolate -- Pea protein isolate; BCA bicinchoninic acid -- DH degree of hydrolysis -- FTIR Fourier-transformed infrared spectroscopy -- HPSEC high performance size exclusion chromatography -- OPA ortho-phtalaldehyde -- PPI pea protein isolate -- SPI soy protein isolate; Food industry and trade -- Periodicals; Food -- Composition -- Periodicals; Microbiology -- Periodicals; Nutrition -- Periodicals; 664.005
• DOI: 10.1016/j.lwt.2019.108795
• Languages: English
• ISSNs: 0023-6438

Abstract

Abstract: The quickly expanding field of plant-based food, generally uses protein concentrates or isolates as protein source. It is however not clear to what extent the intensive processing of these raw materials affects their digestibility. We here report on the in vitro gastric digestibility of the structures present in unheated and heated dispersions of spray-dried protein isolates of soybean and yellow pea. Unheated dispersions consist primarily of insoluble individual spray-dried particles, agglomerates of these and only a small fraction of soluble protein. Pepsin activity was followed in real-time through microscopic observations, showing the disassociation of agglomerates and inward-breakdown of individual particles, which are otherwise stable at gastric pH and ionic strength. This demonstrates that solubility is not necessarily an incentive for gastric protein digestion. Heating does not significantly affect the overall digestibility of protein isolate dispersions. Nevertheless, heating disrupts the structure of spray-dried particles, increasing the amount of smaller and better digestible particles that remain suspended after centrifugation. Conversely, heat-induced aggregates remain in the pellet and are up to 50% less digestible than their unheated counterparts. This impaired digestibility is counterbalanced by a reduced proportion of poorly-digestible species in the full system (up to 11% for soy and 23% for pea). Graphical abstract: Species found in supernatants and pellets of unheated and heated dispersions of soy or pea protein isolates. Ratios corresponding to pea protein isolate. Image 1 Highlights: Microstructure and solubility affect gastric digestibility of plant protein isolates. Solubility is not necessarily an incentive for gastric digestion. Heating did not affect protein digestibility in dispersions of spray-dried isolates. Heat-induced aggregation reduced susceptibility of proteins to pepsin hydrolysis.