Development and optimization of a scalable process to produce protein isolates from sunflower

Le tourteau de tournesol, coproduit du procédé d’extraction d’huile, est une source importante de protéines (30−70 % de la matière sèche). Ces protéines sont composées de deux fractions principales : les globulines (hélianthinines) et les albumines (SFA). Grâce à un profil équilibré en acides aminés et de bonnes propriétés fonctionnelles, elles présentent un fort potentiel d’utilisation comme isolat pour l’alimentation humaine. Cependant, la littérature montre de nombreux verrous scientifiques quant à la production d’isolats de protéines de tournesol. Ces verrous sont liés aux interactions protéine-acide chlorogénique (composé phénolique principal hydrosoluble du tournesol), à la faible extractabilité des protéines du tourteau et la dénaturation irréversible des helianthinines lors de la purification par précipitation acide. L’objectif de ces travaux a donc été de lever ces verrous et, ainsi, de proposer des voies extrapolables de production d’isolats de protéines de tournesol. La première partie de thèse a reposé sur le développement d’une méthode de dosage simultané des protéines, des isomères de l’acide chlorogénique libres et de l’acide chlorogénique lié aux protéines. Cet outil analytique a permis d’avoir un accès rapide et fiable sur les critères de performances cruciaux pour la mise au point et l’optimisation des conditions de production. Dans la deuxième partie de thèse, une condition optimale d’extraction des protéines totales de tourteau de tournesol qui maximise le rendement et minimise les interactions protéine-phénol a été recherchée. Pour cela, une démarche d’optimisation multicritère reposant sur des outils de planification expérimentale et des algorithmes génético-évolutionnaires a été mise en œuvre. Ensuite, une méthode alternative de purification des protéines par ultrafiltration a été mise au point. Cette partie a permis d’améliorer le niveau de compréhension scientifique de l’extraction des protéines de tournesol et a abouti à un produit satisfaisant. Toutefois, il s’avère que le tourteau résiduel post-extraction a été appauvri en protéines et reste riche en acide phytique (facteur antinutritionnel). La troisième partie de thèse a donc été focalisée sur la mise en place d’une stratégie alternative de l’extraction sélective des albumines. Pour ce faire, la méthodologie de modélisation et d’optimisation multicritère, utilisée dans la deuxième partie de thèse, a permis d’identifier des conditions optimales d’extraction sélective des albumines, avec un bon rendement et maintiennent une valeur satisfaisante du tourteau résiduel. Les albumines ainsi extraites étaient très peu colorées, riches en acides aminés soufrés et d’une solubilité plus importante que les protéines totales. Les propriétés fonctionnelles des albumines (moussantes, émulsifiantes) ont été supérieures ou proches de celles de protéines de soja. La stratégie mise en place a donc permis de développer un procédé durable de production des albumines ayant un fort potentiel d’utilisation en nutrition humaine et un tourteau résiduel pour des applications en alimentation animale.Sunflower meal, by-produced after oil extraction process, is a valuable source of proteins (30−70% on dry matter basis). These proteins are composed of two main fractions: globulins (helianthinins) and albumins (SFA). Thanks to well-balanced amino acid composition and good functional properties, they are considered very promising for human nutrition as protein isolates. However, the literature shows many scientific drawbacks during sunflower protein extraction and purification. These drawbacks lie on interaction between proteins and chlorogenic acid (major hydrosoluble phenolic compound of sunflower), poor extraction yield and helianthinin denaturation during protein purification by acidic precipitation. The goal of this thesis work was to overcome these limitations and to propose a scalable process for production of sunflower protein isolates. The first part of the thesis was based on the development of a new method for simultaneous quantification of proteins, free chlorogenic acid isomers and chlorogenic acid bound to proteins. This analytical tool provided fast and reliable access to performance criteria crucial for further development and optimization of sunflower protein production process. In the second part of the thesis, an optimal condition for extraction of total proteins from sunflower meal allowing maximizing extraction yield and minimizing protein-phenol interaction was searched. For this purpose, multicriteria optimization based on modelling by design of experiments and genetico-evolutionary algorithms was applied. Then, an alternative method for protein purification by ultrafiltration was developed. This part of study has improved the global understanding of sunflower protein extraction process and yielded in a satisfactory product. However, the residual meal produced after protein extraction was poor in proteins and rich in phytic acid (antinutritional factor). The third part of the thesis was therefore focused on the implementation of an alternative strategy of selective extraction of albumins. To do so, the methodology of modelling and multicriteria optimization, used in second part of the thesis, allowed to identify the optimal conditions for selective extraction of albumins with good yield keeping a satisfactory value of the residual meal. The extracted albumins were light-coloured, rich in sulphur-containing amino acids and more soluble than total sunflower proteins. The functional properties of albumins (foaming, emulsifying) were improved or comparable to those of soy proteins. Therefore, the established strategy provided a sustainable process for production of albumins that would be used in human nutrition and residual meal for feed applications

Improved rapeseed oil extraction yield and quality via cold separation of ethanol miscella

In the extraction of vegetable oils, the idea of using ethanol as a solvent, allowing solvent recycling without distillation, can be attested as early as 1948 (Beckel), yet it is now seldom envisaged. The development of organic farming and a growing demand for a more natural diet prompted us to revisit this approach, which takes advantage of the relatively low affinity of ethanol for lipids to produce pure crude oils and meal with higher protein content. This method is based on the change of oil solubility in ethanol with temperature. Rapeseed oil extraction was carried out by hot pressurized ethanol (subcritical extraction condition). Oil was then recovered by cooling the miscella and demixing of two phases, an oil-rich phase and a solvent-rich phase. This study, after verifying the kinetics of extraction, focused on the optimization of the demixing temperature based on the amount and quality of recovered oil. The results show that ethanol extraction followed by cold demixing of the miscella makes it possible to obtain a high quality oil, free of free fatty acids and phospholipids

Improved rapeseed oil extraction yield and quality

In the extraction of vegetable oils, the idea of using ethanol as a solvent, allowing solvent recycling without distillation, can be attested as early as 1948 (Beckel), yet it is now seldom envisaged. The development of organic farming and a growing demand for a more natural diet prompted us to revisit this approach, which takes advantage of the relatively low affinity of ethanol for lipids to produce pure crude oils and meal with higher protein content. This method is based on the change of oil solubility in ethanol with temperature. Rapeseed oil extraction was carried out by hot pressurized ethanol (subcritical extraction condition). Oil was then recovered by cooling the miscella and demixing of two phases, an oil-rich phase and a solvent-rich phase. This study, after verifying the kinetics of extraction, focused on the optimization of the demixing temperature based on the amount and quality of recovered oil. The results show that ethanol extraction followed by cold demixing of the miscella makes it possible to obtain a high quality oil, free of free fatty acids and phospholipids

A Rational Approach for the Production of Highly Soluble and Functional Sunflower Protein Hydrolysates

Exploitation of plant proteins as an alternative to animal proteins currently presents an important challenge for food industries. In this contribution, total sunflower protein isolate from cold press meal was used as a starting material for the generation of highly soluble and functional hydrolysates that could be used in various food formulations. To do this, a rational and complete approach of controlled hydrolysis was implemented using the individual Alcalase and Prolyve enzymes. The method of stopping the hydrolysis reaction was also evaluated. The influence of operating conditions on hydrolysis kinetics and enzymatic mechanism was studied to identify the appropriate hydrolysis conditions. The gain of the solubility was then analyzed and compared to that of the initial proteins. Finally, the emulsifying and foaming properties (capacities and stabilities) of the resulting hydrolysates were also assessed. As a result, controlled enzymatic proteolysis significantly improved the sunflower protein solubility at neutral pH (twofold increase) and generated highly soluble hydrolysates. The limited proteolysis also maintained the good foam capacities and allowed an improvement in the initial foam stabilities and emulsifying capacities and stabilities of sunflower proteins. This contribution can greatly increase the value of sunflower meal and help in the development of sunflower protein products in the future

A new SE-HPLC method for simultaneous quantification of proteins and main phenolic compounds from sunflower meal aqueous extracts

International audienceThe aim of this research was to develop a method for simultaneous quantification of proteins and main polyphenolic compounds extracted from oleaginous meal by aqueous media. Size exclusion chromatography with a Biosep column (exclusion range from 1 to 300 kDa) and acetonitrile/water/formic acid (10:89.9:0.1 v/v) eluent at 0.6 mL min−1 yielded the most efficient separation of sunflower proteins and chlorogenic acid monoisomers (3-caffeoylquinic acid, 5-caffeoylquinic acid, and 4-caffeoylquinic acid). After a study of the stability of the extract components, the incorporation of a stabilization buffer (0.5 mol L−1 tris(hydroxymethyl)aminomethane-hydrochloric acid/1.0 mol L−1 sodium chloride at pH 7) was proposed to avoid polyphenol-protein interactions and/or isomeric transformation. The use of 214 nm as the wavelength for protein quantification was also included to minimize the effect of interference from polyphenol-protein interactions on the quantification. Under the used experimental conditions, the protein and chlorogenic acid monoisomer signals remained stable during 300 min at 20 °C (95–125% of the starting value). The developed method was validated and parameters such as specificity, sensitivity, precision, and accuracy were determined. The results from size exclusion chromatography correlated well with the results of protein determination by the reference Kjeldahl method. The proposed method was successfully applied for rapeseed extract analysis making simultaneous quantification of proteins and major rapeseed polyphenols (sinapine and sinapic acid) possible

A new size-exclusion chromatography method for fast rapeseed albumin and globulin quantification

International audienc

Optimization of sunflower albumin extraction from oleaginous meal and characterization of their structure and properties

International audienc