Fermentation of Texturized Pea Protein in Combination with Proteases for Aroma Development in Meat Analogues

The potential use of texturized pea protein in meat analogues was investigated by comparing the effects of fermentation on pea and myofibrillar pork proteins in a model system including additives, microbial starters, and proteases. Model fermentation was controlled for 15 days by a pH decrease and microbial count and free amino acid increase. Besides, volatile production and sensory properties were evaluated at the end of fermentation. Protein type affected free amino acid generation and volatile profile. Models supplemented with proteases showed an increase in amino-acid-derived compounds (branched aldehydes and alcohols) and fruity odor notes. During fermentation, protease addition significantly reduced the production of linear aldehydes (pentanal, hexanal, and octanal) in vegetal models, while pyrazine compounds were not affected. This changes in the volatile profile reduced the legume beany odor but increased the perception of toasted cereal-like notes generated by the texturization process.

Table S3.Microbial counts (log cfu/g) and pH from the fermentative process of the vegetal models without and with proteolytic enzyme.Samples were taken at 0, 3, 8 and 15 days of incubation.
Table S4.Free amino acids content (mg/g protein) in the animal model without and with proteolytic enzyme.Samples were taken at 0, 3, 8 and 15 days of incubation.

Animal model without enzyme
Animal Animal models containing myofibrillar proteins without (A) and with (AE) enzyme at 0, 3, 8 and 15 d of incubation. 2 RMSE: root mean square of the errors.
3 Pf: P value of the time effect, P E : P value of enzyme effect, P txE : P value of interaction between time and enzyme effects.***: P < 0.001; **: P < 0.01; *: P < 0.5; ns: P > 0.05. 4 Different letters in the same row indicate significant differences among models and times.
Table S5.Free amino acids content (mg/g protein) in the vegetal model without and with proteolytic enzyme.Samples were taken at 0, 3, 8 and 15 days of incubation.

Vegetal model without enzyme
Vegetal model with enzyme Vegetal models containing texturized pea protein without (V) and with (VE) enzyme at 0, 3, 8 and 15 d of incubation. 2 RMSE: root mean square of the errors. 3Pf: P value of the time effect, P E : P value of enzyme effect, P txE : P value of interaction between time and enzyme effects.***: P < 0.001; **: P < 0.01; *: P < 0.5; ns: P > 0.05. 4 Different letters in the same row indicate significant differences among models and times.
Table S6.Volatile compounds identified in the headspace of the animal and vegetal models.Animal models contain myofibrillar proteins without (A) and with (AE) enzyme.Vegetal models contain texturized pea protein without (V) and with (VE) enzyme.Tr: retention time, 2 LRI: Linear retention indices of the compounds (LRI DB624) or standards (LRI-std) eluted from GC-MS using a DB-624 capillary column. 3Reliability of identification: a, identification by mass spectrum and by coincidence with the LRI of an authentic standard; b, tentatively identification by mass spectrum. 4(s) present in model, (n) absent in model. 5Target ion (m/z in parenthesis) used to quantify the compound when the peak was not completely resolved.

Compound
Table S7.Volatile compounds content (AU 10 -5 /g protein) in the headspace of the animal models (containing myofibrillar proteins) without and with proteolytic enzyme.Samples were taken at 0, 3, 8 and 15 days of incubation.Table S8.Evolution of the content of volatile compounds (AU 10 -5 /g protein) in the headspace of vegetal models (containing pea protein) without and with proteolytic enzyme.Samples were taken at 0, 3, 8 and 15 days of incubation.