Protein Oxidation and In Vitro Gastric Digestion of Processed Soy-Based Matrices

Abstract

Process conditions that are applied to make structured soy-protein-based food commonly include high temperatures. Those conditions can induce protein oxidation, leading to a decrease in their susceptibility to proteolysis by digestive enzymes. We aimed to investigate the effects of thermomechanical processing on oxidation and in vitro gastric digestion of commercial soy protein ingredients. Samples were sheared at 100 to 140 °C and characterized for acid uptake, carbonyl content, electrophoresis, and surface hydrophobicity. The enzymatic hydrolysis was determined in simulated gastric conditions. Protein ingredients were already oxidized and showed higher surface hydrophobicity and hydrolysis rate compared with those of the processed matrices. However, no clear correlation between the level of carbonyls and the hydrolysis rate was found. Therefore, we conclude that gastric digestion is mostly driven by the matrix structure and composition and the available contact area between the substrate and proteolytic enzymes.

Texturization of a Blend of Pea and Destarched Oat Protein Using High-Moisture Extrusion

“…For example, Palanisamy et al [ 52 ] showed that lupin proteins extruded at temperatures from 135 to 180 °C and at moisture contents from 40 to 55% had 3 to 6% higher digestibility compared to the untreated raw material. Furthermore, Duque-Estrada et al [ 53 ] studied a soy protein meat analog that was made with a high-temperature shear cell at temperatures of 100 to 140 °C. They reported that the in vitro protein digestibility of soy proteins did not decrease despite the decrease in the protein solubility and the higher level of carbonyls in the protein due to the thermomechanical treatment.…”

Animal and Plant Protein Oxidation: Chemical and Functional Property Significance

“…More recently, Xu et al [ 37 ] confirmed that moderate oxidation in an iron–ascorbate system with 1–15 mM H 2 O 2 not only improved emulsifying properties of β-conglycinin but also reduced its allergenicity. It is worth noting that, because oxidation could both modify enzyme-accessible amino acid residues and alter the conformational structure to expose enzyme-susceptible peptide bonds, oxidation can result in either decreased or increased digestibility of soy proteins [ 23 , 94 , 95 ]. The degree of digestion is ultimately determined by the matrix structure and composition of affected proteins.…”

“…Several early investigations have shown that, as is in living tissues, ROS can cause food proteins to polymerize, degrade, and interact with other food components to produce complexes [ 5 , 6 , 7 , 8 ]. Subsequent research, including recent studies, has produced ample new evidence that ROS-induced physicochemical modifications could significantly alter the functionality (i.e., gelation, emulsification, foaming, film formation, and water-binding) of muscle [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ], egg [ 16 , 17 ], dairy [ 18 , 19 , 20 , 21 ], legume [ 22 , 23 , 24 , 25 ], and cereal [ 26 , 27 , 28 ] proteins. Table 1 lists the proteins from different commodity food groups that have been widely subjected to oxidative studies.…”

Effects of Cavitation Jet Treatment on the Structure and Emulsification Properties of Oxidized Soy Protein Isolate

“…Due to its unique nutritional value and excellent functional properties, soy protein has become one of the most important food ingredients widely used in the food industry [ 1 , 2 ]. At present, soybean protein isolate (SPI) is prone to oxidation and aggregation during storage and transportation, resulting in the loss of protein nutrition, quality degradation, and loss of some functional properties, such as solubility, gelation, and emulsification [ 3 , 4 ]. Protein oxidation is the covalent modification of a protein directly induced by reactive oxygen species or indirectly induced by reaction with secondary by-products of oxidative stress [ 5 ].…”

“…AAPH oxidation leads to the formation of carbonyl groups, the degradation of free sulfhydryl groups, and the formation of dihydrotyrosine in SPI. Oxidative modification results in the breaking of the main chain of proteins, a decrease in solubility and interfacial activity, and the formation of oxidative aggregates [ 3 , 14 ].…”