Proteínas do soro de leite: estrutura, propriedades espumantes e habilidade de ligar luteína e ácido fólico

Author(s)

Danilo Corsi Vidotto

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos
• Defense date: 2022-10-27

Examining board members

Guilherme Miranda Tavares; Ruann Janser Soares de Castro; Miriam Dupas Hubinger; Paulo Cesar Stringheta; Antônio Fernandes de Carvalho

• Advisor: Guilherme Miranda Tavares

Abstract

Whey proteins are valuable ingredients for the food industry given their techno-functionality and high nutritional value. Such techno-functionalities, as foaming properties and the ability of binding small ligands, are dictated by protein structure. In this context, the aim of this thesis was to evaluate the relation between whey protein structure, its techno-functionality (foaming properties), and the ability to bind and protect bioactive compounds (lutein and folic acid). Firstly, dry heating (DH) was applied to whey protein isolate (WPI) powder, supplemented or not with lactose, in neutral and alkaline environments. Even for the untreated powders, the alkaline environment, by itself, triggered the formation of insoluble protein aggregates, that formation of aggregates was potentialized with lactose addition and high temperatures of DH. These insoluble aggregates presented high water absorption capacity. DH under neutral and alkaline environments led to the formation of soluble aggregates, however, only an alkaline environment produced soluble aggregates that enhanced the foam stability. Another protein techno-functionality, the ability to bind bioactive compounds, was evaluated for the main whey proteins, beta-Lactoglobulin and alpha-Lactalbumin. Both proteins had their ability to bind folic acid and lutein in the absence or presence of folic acid evaluated. Results pointed out that, even though the preferable region of interaction of both ligands was the same in each protein, they were able to bind folic acid and lutein simultaneously. Besides, the interaction with both ligands induced minimal alterations to protein structure and denaturation temperature. Finally, the impact of dynamic high-pressure microfluidization (DHPM) on the structure of WPI and beta-Lactoglobulin was evaluated, associated or not to the control of intrinsic heating of the process (cooling). In addition, the influence of the structural changes observed after DHPM on the interaction protein-lutein and on the functionality of the complexes formed was studied. Results pointed out minimal alterations to protein structure when samples were cooled after each microfluidization cycle. However, when the process was associated with the intrinsic heating of the process (without cooling), WPI dispersions presented slight aggregation. Regarding the interaction with lutein, both WPI and beta-Lg had association constants in the order of magnitude of 10E4 M E(-1), regardless of the treatments applied. When complexed with proteins, lutein showed a 3-fold lower photodegradation constant compared to the absence of proteins. This thesis gathers relevant information for the development of new protein-rich food products, free or with reduced lipid content, and with the potential to carry and protect bioactive compounds, such as lutein (AU)

• FAPESP's process: 18/09304-6 - Interaction between carotenoids and native and non-native globular proteins from milk: structural and functional effects in mono and multi protein systems
• Grantee: Danilo Corsi Vidotto
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)