Extraction and modification by moderate electric filed of protein from lentil (Lens culinaris) for application in coacervates systems

Author(s)

Cristiane Grella Miranda

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos
• Defense date: 2020-03-10

Examining board members

Ana Carla Kawazoe Sato; Flavia Maria Netto; Talita Aline Comunian

• Advisor: Louise Emy Kurozawa; Ana Carla Kawazoe Sato

Abstract

This study aimed to evaluate the process of extracting lentil proteins to produce complex coacervates with pectin. The obtaining of protein extracted by the alkaline method (LPI-EA) and the alkaline method assisted by carbohydrases (LPI-EZ) or by ultrasound-assisted (LPI-US) was evaluated. The protein isolates obtained in the conditions with the highest extraction yield in the first step were evaluated by analysis of proximate composition, electrophoresis, zeta potential, solubility and interfacial tension. Significant differences were not observed (p> 0.05) between extraction yields comparing the different methods studied. After obtaining lentil protein isolates, LPI-EA and LPI-EZ showed a protein content higher than LPI-US. The treatments associated with alkaline extraction (ultrasound-assisted and enzymatic treatment) did not cause changes in the neutral charge condition or in the molecular mass profile of the protein. However, differences were observed in the solubility profile and in the interfacial tension decrease rate, indicating that extraction processes can modify the functionalities of the protein. The effect of thermal and ohmic heating (OH) on the structure of the protein extracted by the alkaline process as well as evaluated the formation process of coacervates were also studied. Changes on secondary and tertiary structure of the protein isolated by application of OH at different temperatures, time and strength of the electric field were evaluated. Significant changes in secondary structure were not observed after treatment of LPI-EA with OH. The reductions in the tryptophan fluorescence due to the OH temperature and the exposure time indicated alteration of the tertiary structure. The tryptophan fluorescence increase was also verified in conventional treatment. These results indicate that OH process is able to modify the lentil protein, depending on the temperature, exposure time and strength of the electric field. The conditions of formation of coacervates were optimized in relation to the formation pH, protein: pectin ratio and proportion of biopolymers: oil. Both coacervates produced with isolated protein obtained by different extraction process and coacervates obtained with LPI-EA treated with OH were characterized by Fourier transform spectrophotometry (FTIR). The high encapsulation efficiency (above 90%) was observed in the all biopolymers: oil ratio, with a 1: 1 ratio being higher (p <0.05). Finally, coacervates obtained using LPI-EZ, LPI-US and LPI-EA treated with OH with a high intensity of electric field, indicate involvement of other functionals groups that do not participating coacervation using LPI-EA. The association of pre-treatments (ultrasound and enzymes) to alkaline extraction did not result in significative difference on protein yield, but promoted significant differences in solubility and interfacial for the different isolates. Changes in the structure of the lentil protein by OH were dependent of temperature, time of exposure and intensity of the electric field. The linseed oil encapsulation was efficient, with high encapsulation efficiency for all the ratios biopolymers: oil used. The functional groups involved in the formation of coacervates were shown to be dependent on the type of treatment applied to IPL-EA (AU)

• FAPESP's process: 18/16456-7 - Complex coacervation using lentil protein obtained by different methods of extraction
• Grantee: Cristiane Grella Miranda
• Support Opportunities: Scholarships in Brazil - Master