Emulsion properties of sunflower (Helianthus annuus) proteins

Sensitization Potency of Sunflower Seed Protein in a Mouse Model: Identification of 2S-Albumins More Allergenic Than SFA-8

SCOPE

Food allergy to sunflower seed (SFS) protein is not frequent and only non-specific lipid transfert protein (nsLTP) Hel a 3 is officially recognized as a food allergen. Out of the eleven seed storage 2S-albumins (SESA) detected in SFS, only SFA-8 allergenicity has been investigated so far. The study aimed then to evaluate SFS protein allergenicity and particularly, to compare the sensitization potency of SESA in a mouse model.

METHODS AND RESULTS

The most abundant SESA and nsLTP were isolated from SFS through a combination of chromatographic methods. Purified proteins were then used to measure specific IgG1 and IgE responses in BALB/c mice orally sensitized to different SFS protein isolates. The study, thus, confirmed the allergenicity of SFA-8 and Hel a 3 but mice were also highly sensitized to other SESA such as SESA2-1 or SESA20-2. Furthermore, competitive inhibition of IgE-binding revealed that SFA-8 IgE-reactivity was due to cross-reactivity with other SESA. 11S-globulins were weakly immunogenic and were rapidly degraded in an in vitro model of gastroduodenal digestion. In contrast, Hel a 3, SESA2-1 and SFA-8 were more resistant to proteolysis and gastroduodenal digestion did not affect their IgE-reactivity.

CONCLUSIONS

SESA2-1 or SESA20-2 were more potent allergens than SFA-8 in this mouse model. Allergenicity of SESA must be now confirmed in SFS-allergic patients.

Alternative Protein Sources as Technofunctional Food Ingredients

Proteins obtained from alternative sources such as plants, microorganisms, and insects have attracted considerable interest in the formulation of new food products that have a lower environmental footprint and offer means to feed a growing world population. In contrast to many established proteins, and protein fractions for which a substantial amount of knowledge has accumulated over the years, much less information is available on these emerging proteins. This article reviews the current state of knowledge on alternative proteins and their sources, highlighting gaps that currently pose obstacles to their more widespread application in the food industry. The compositional, structural, and functional properties of alternative proteins from various sources, including plants, algae, fungi, and insects, are critically reviewed. In particular, we focus on the factors associated with the creation of protein-rich functional ingredients from alternative sources. The various protein fractions in these sources are described as well as their behavior under different environmental conditions (e.g., pH, ionic strength, and temperature). The extraction approaches available to produce functional protein ingredients from these alternative sources are introduced as well as challenges associated with designing large-scale commercial processes. The key technofunctional properties of alternative proteins, such as solubility, interfacial activity, emulsification, foaming, and gelation properties, are introduced. In particular, we focus on the formation of isotropic and anisotropic structures suitablefor creating meat and dairy product analogs using various structuring techniques. Finally, selected studies on consumer acceptance and sustainability of alternative protein products are considered.

Sunflower Proteins at Air-Water and Oil-Water Interfaces

The adsorption of a sunflower protein extract at two air-water and oil-water interfaces is investigated using tensiometry, dilational viscoelasticity, and ellipsometry. For both interfaces, a three step mechanism was evidenced thanks to master curve representations of the data taken at different aging times and protein concentrations. At short times, a diffusion limited adsorption of proteins at interfaces is demonstrated. First, a two-dimensional protein film is formed with a partition of the polypeptide chains in the two phases that depends strongly on the nature of the hydrophobic phase: most of the film is in the aqueous phase at the air-water interface, while it is mostly in the organic phase at the oil-water interface. Then a three-dimensional saturated monolayer of proteins is formed. At short times, adsorption mechanisms are analogous to those found with typical globular proteins, while strong divergences are observed at longer adsorption times. Following the saturation step, a thick layer expands in the aqueous phase and appears associated with the release of large objects in the bulk. The kinetic evolution of this second layer is compatible with a diffusion limited adsorption of the minor population of polymeric complexes with hydrodynamic radius R_H ∼ 80 nm, evidenced in equilibrium with hexameric globulins (R_H ∼ 6 nm) in solution. These complexes could result from the presence of residual polyphenols in the extract and raise the question of the role of these compounds in the interfacial properties of plant protein extracts.

USING SUMFLOWER PROTEIN AS A COMPONENT OF FORCEMEATS FOR FROZEN SEMI-PROCESSED MINCED MEAT PRODUCTS

The problem of how to remediate protein deficiency in the human diet can be solved by using new raw material sources or by consuming vegetable proteins, in particular, sunflower protein, more efficiently. Sunflower is high in biologically complete proteins with a wide range of functional properties. This makes it practical to use sunflower protein as a component of forcemeats for frozen semi- processed minced meat products. As this task is highly topical and promising, it has determined the direction of further research. The purpose of the research is to establish how sunflower protein affects the qualitative characteristics of forcemeat for frozen semi-processed minced meat products, and to specify the rational norms of using it in their composition. It has been studied how sunflower protein effects on the moisture-holding capacity of forcemeat. The results have shown a sharp increase in this parameter after introducing sunflower protein. It has been established that sunflower protein affects the processes of freezing and defrosting in forcemeat systems. However, it has no pronounced cryoprotective properties independent of  its concentration in a system, and the loss in weight during freezing the samples is but insignificant. Studying the effect of sunflower protein powder on the sensory, functional, and technological properties of forcemeat reveals positive dynamics and direct relationship between these characteristics and the concentration of sunflower protein. The losses in the weight of the semi-processed products during heat treatment have been analysed. The   data   obtained  have  shown  that   this   parameter   decreases   by 1.9 times when sunflower protein is used. Sensory evaluation of the samples has allowed establishing that the rational norm for sunflower protein as a forcemeat component is up to 10%. Thus, the research conducted prove that it is practical to use sunflower proteins as components of forcemeats for frozen semi-processed minced meat products. This will make the products more nutritious, allow controlling their amino acid composition, curtail the expenditure of raw meat, help control the rheological parameters, and expand the range of products.

Localized enzymolysis and sonochemically modified sunflower protein: Physical, functional and structure attributes

Impacts of localized enzymolysis and sonication on physical, techno-functional, and structure attributes of sunflower meal protein (SMP) and its hydrolysate (SMPH) were studied. SMP was subjected to enzymolysis (using alcalase) to prepare SMPH with various degrees of hydrolysis (6-24% DH). Enzymolysis decreased colour lightness, turbidity, and particle size of unsonicated and sonicated SMP, while it increased the absolute values of zeta potential (P < 0.05). Sonication improved oil absorption capacity and dispersibility over unsonicated samples. Contrarily, sonicated preparations showed a decrease in water holding capacity. Intrinsic fluorescence and FTIR spectral analyses suggested that SMPH had more movable/flexible secondary structures than SMP. Moreover, the changes in sulfhydryl clusters and disulfide linkages following sonication demonstrated limited unfolding of SMP and SMPH structure and decrease in intermolecular interactions. SDS-PAGE profile exhibited significant reduction in molecular weight (MW) of sonicated SMP, whereas did not display differences between unsonicated and sonicated SMPH. From further MW analysis, SMPH was categorized with high proportion of small-sized peptides ≤ 3 kDa fractions, which increased from 78.64 to 93.01% (control) and from 82.3 to 93.88% (sonication) with enzymolysis (6-24DH). Localized enzymolysis and sonication can be utilised to modify the physical and conformational attributes of SMP and SMPH, which could enhance their functionalities and broaden the utilisation area in food industry.

Multi-objective optimization of solid/liquid extraction of total sunflower proteins from cold press meal

The impact of pH (6-9) and NaCl concentration (0-0.5 mol.L^-1) on sunflower protein extraction was studied through design of experiments. The considered criteria were protein extraction yield (total proteins, helianthinin and albumins), chlorogenic acids covalently bound to proteins, and free chlorogenic acid concentration in the aqueous extract. Statistical analysis showed that the obtained by design of experiments the polynomial models of each extraction criteria were reliable for predicting the responses. They were employed in an original multi-objective optimization methodology. The optimal conditions revealed to be pH 7.3/0.3 mol.L^-1 NaCl yielded 46.83% and 59.16% of total protein and albumin extraction yield, 1.730 and 1.998 mg.g^-1 of chlorogenic acids covalently bound to helianthinin and albumins in aqueous extract, respectively. The sunflower protein isolate obtained after extraction in this condition had good solubility (40-80% at pH 5-8), functional properties (foaming and emulsifying) and a satisfying color.

Curcumin-sunflower protein nanoparticles-A potential antiinflammatory agent

Curcumin is an antiinflammatory molecule, however, due to its lipophilic nature, has the limitation of very low aqueous solubility and degrades rapidly when dispersed in aqueous media. The potential of sunflower seed protein isolate (SFPI), one of the underutilized plant protein, as a drug carrier was studied by synthesizing SFPI nanoparticles (NPs) and encapsulating curcumin in NPs. Increase in solubility of encapsulated curcumin was observed with an encapsulation efficiency of 83%. Stability studies showed that curcumin-SFPI NPs are stable in water and in gastrointestinal condition. The mechanism of interaction of curcumin involves the binding with the hydrophobic patches of protein. In complex with NPs, curcumin showed potent antioxidant activity; antiinflammatory effect of curcumin was studied by following lipoxygenase inhibition (IC₅₀  = 45.3 µM). The study explores the potential of sunflower seed protein to be used as carrier for delivery of nutraceutical by taking curcumin as model compound. PRACTICAL APPLICATIONS: Sunflower seed protein is one of the versatile, quality proteins found in abundance; yet it is an underutilized plant protein. The study exploits the use of sunflower seed protein as a delivery system for lipophilic nutraceuticals by synthesizing NPs and encapsulating them. Solubility and stability of curcumin is increased along with enhanced antioxidant and antiinflammatory activity in complex with SFPI NPs when compared to free curcumin.

Functional properties of Ditaxis heterantha proteins

Ditaxis heterantha is a plant of the Euphorbiaceae family that grows in semiarid regions of Mexico. It produces yellow pigmented seeds that are used for coloring of foods. The seeds contain about 20% of proteins. Proteins of D. heterantha were extracted and fractionated on the basis of solubility. Three main protein fractions were obtained: glutelins, 488 ± 0.5; albumins, 229 ± 2; and total globulins, 160 ± 1 g/kg. The amino acid profile was evaluated for each fraction and protein isolated, where the protein isolate contains essential amino acids such as Val, Phe, Tyr, and Leu. A calorimetric study showed that globulins and glutelins have a high denaturing temperature between 100 and 106°C, while albumins showed a denaturing temperature at 76°C. The protein isolate and its fractions exhibited functional properties: the isolated protein demonstrated good oil‐holding capacity of 40.7 g/kg. Foam capacity (FC) and foam stability (FS) were observed principally in glutelins and globulins where FC maximum was 330% and the FS was 28 min. The emulsifying capacity was observed in the same fractions of glutelins and globulins, followed by albumins. However, the glutelin fraction in particular was the only fraction that exhibited emulsifying stability at pH 5, 6, and 7. Gelling capacity was observed in albumins and globulins. This study indicated that protein isolated from D. heterantha could be used in food formulations due to its essential amino acid profile. Glutelin could be used as an emulsifying additive. Additionally, glutelin and globulin were stable at temperatures above 100°C; this is an important factor in food industry, principally in heat processes.

Production of low chlorogenic and caffeic acid containing sunflower meal protein isolate and its use in functional wheat bread making

Sunflower meal protein isolate (SMPI) is a promising food additive in different matrices. However, the uses of SMPI are limited because of the presence of antinutritional compounds like polyphenolic substances. Chlorogenic and caffeic acids are the dominants polyphenolics in the SMPI. These substances cause significant changes of the colour of the meal, proteins and food matrices during their extraction and use as food additives. Moreover, these substances lower the nutritional value of the end product due to their interaction with some amino acids such as lysine and methionine. Thus, the removal of these substances is important to enable the use of the SMPI and meal in general in a greater extent in food applications and replacing more expensive protein sources such as soy proteins. The aim of this work was to study the production of functional bread by supplementing wheat flour with sunflower meal protein isolate (SMPI). SMPI with low content of chlorogenic and caffeic acid was usefully produced following alkaline extraction and purification with succinic acid. Purified SMPI showed well balanced amino acid profile and was characterized by high water and fat absorption capacities. It was incorporated to dough formula at 8-12 % of the total wheat flour. The results showed that production of bread supplemented with SMPI was technologically feasible. The supplemented bread had high mass volume and nutritional quality compared to the control bread. The optimal SMPI to incorporate into dough formula without significant alteration of the final bread colour was established at 10 %. This study will be helpful to find economic ways to enhance the nutritional quality of wheat bread and to improve the profitability of sunflower meal residue.