Optimization of protein extraction from flaxseed meal

Quantification of crustacean tropomyosin in foods using high-performance liquid chromatography-tandem mass spectrometry method

BACKGROUND

Allergic reactions to crustacean products have been increasing owing to the rising consumption. Tropomyosin (TM) is the main crustacean allergen; it has a coiled-coil structure, which shows stability to various food processing methods. Crustacean processed products have been used in several food products, thereby causing greater difficulties in detecting TM in these products. We aimed to develop an assay based on high-performance liquid chromatography-tandem mass spectrometry for the accurate and reproducible quantification of crustacean TM in foods.

RESULTS

The three peptides IQLLEEDLER, LAEASQAADESER, and IVELEEELR were selected as peptide markers, and the peptide IVELEEELR was selected as the quantitative marker. Extraction conditions and enzymatic digestion conditions were completely optimized. The extraction solution of Tris-hydrochloric acid buffer (50 mmol L^-1 , pH 7.4) containing 1 mol L^-1 potassium chloride and the enzymatic treatment at 1:15 ratio (enzyme/protein, m/m) for 13 h showed excellent efficiency. The method exhibited a good linear relationship, with the qualified coefficient of determination (R²  = 0.9994) in the wide range of 1 to 1000 μg L^-1 . The accuracy was validated based on spiked recovery at three spiking levels (12.5, 25.0, and 50.0 μg kg^-1 , TM/matrix) in blank matrices that included chicken sausages, beef balls, and egg-milk biscuits. The recoveries ranged from 91% to 109% with qualified relative standard deviations <15% with the limit of quantification (of 1.6 mg kg^-1 , TM/matrix).

CONCLUSION

This new approach can be used for the qualitative and quantitative detection of crustacean TM in various food matrices. © 2021 Society of Chemical 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.

Valorization of Flaxseed Oil Cake Residual from Cold-Press Oil Production as a Material for Preparation of Spray-Dried Functional Powders for Food Applications as Emulsion Stabilizers

Flaxseed oil cake extract (residual from cold-press oil production and rich in proteins and polysaccharides) was evaluated as a potential substrate for the preparation of spray-dried powders with emulsifying activity. Three variants of powders were obtained using different spray-drying process inlet temperatures: 160 °C, 180 °C, and 200 °C. The influence of temperature on physicochemical features (water holding capacity, oil binding capacity, water activity, solubility, color, chemical composition, antioxidant activity, and surface morphology) of the powders was estimated. Additionally, the emulsifying activity of the powders and the stability of oil-in-water emulsions prepared with their various content (0.5%, 1%, and 3%) were determined. Results showed that inlet temperature had significant influence on all physicochemical and functional properties of the powders. Increased inlet temperature decreased solubility and antioxidant activity but increased water-holding capacity, oil-binding capacity, and emulsifying activity. The emulsions prepared with the powder obtained at 200 °C showed the highest stability. SEM images showed the production of relatively spherical particles which were folded or wrinkled with a lot of dentures. This study could open a promising pathway for producing natural and plant-based spray-dried powders for food applications as emulsion stabilizers.

Covalent modification of flaxseed protein isolate by phenolic compounds and the structure and functional properties of the adducts

Covalent modification of flaxseed protein isolate by phenolic compounds including flaxseed polyphenols, ferulic acid, and hydroxytyrosol was studied under alkaline condition and in the presence of oxygen. The structure and function of the adducts was evaluated. The extent of covalent reaction and the physicochemical characteristics of flaxseed protein isolate-phenolic adducts were found to depend on the structure of the phenolic compounds. The decrease in free amino, thiol and tryptophan groups and increase in molecular weight were different. Crosslinks were found in flaxseed protein isolate-hydroxytyrosol adducts while ferulic acid and flaxseed polyphenols were unable to crosslink flaxseed proteins. The thermal stability and antioxidative capacity of the adducts were higher than those of flaxseed protein isolate. The structural conformation and hydrophobicity of the adducts were also found to depend on the nature of phenolic compounds. These adducts can be used in food formulations as natural antioxidants, emulsifiers and encapsulating shell materials.

Recombinant endo-mannanase (ManB-1601) production using agro-industrial residues: Development of economical medium and application in oil extraction from copra

Expression of pRSETA manb-1601 construct in Hi-Control Escherichia coli BL21 (DE3) cells improved recombinant endo-mannanase (ManB-1601) production by 2.73-fold (1821±100U/ml). A low-cost, agro-industrial residue supplemented industrial medium for enhanced and economical production of ManB-1601 was developed in two mutual phases. Phase-I revealed the potential of various pre- (induction time: 5h, induction mode: lactose 0.5mM) and post-induction [peptone supplementation: 0.94%(w/v), glycerol 0.123%(v/v)] parameters for enhanced production of ManB-1601 and resulted in 4.61-fold (8406±400U/ml) and 2.53-fold (3.30g/l) higher ManB-1601 and biomass production, respectively. Under phase-II, economization of phase-I medium was carried out by reducing/replacing costly ingredients with solubilized-defatted flax seed meal (S-DFSM), which resulted in 3.25-fold (5926U/ml) higher ManB-1601 production. Industrial potential of ManB-1601 was shown in oil extraction from copra as enzyme treatment led to cracks, peeling, fracturing and smoothening of copra, which facilitated higher (18.75%) oil yield.

Study of total dry matter and protein extraction from canola meal as affected by the pH, salt addition and use of zeta-potential/turbidimetry analysis to optimize the extraction conditions

Total dry matter and proteins were differentially and preferentially extracted from canola meal (CM) under different conditions. The effect of the extraction medium pH, CM concentration and salt concentrations were found to have different influences on the extractability of total dry matter and proteins from CM. The pH of the extracting medium had the most significant effect. The maximal total dry matter (42.8±1.18%) extractability was obtained with 5% CM at pH 12 without salt addition, whereas the maximal for total protein (58.12±1.47%) was obtained with 15% CM under the same conditions. The minimal extractability for the dry matter (26.63±0.67%) was obtained with 5% CM at pH 10 without salt added and the minimal protein extractability was observed in a 10% CM at pH 10, in 0.01 NaCl. Turbidity and ζ-potential measurements indicated that pH 5 was the optimum condition for the highest protein extraction yield. SDS-PAGE analysis showed that salt addition contributes to higher solubility of canola proteins specifically cruciferin fraction, although it reduces napin extraction.

Effect of Extraction Method on the Phenolic and Cyanogenic Glucoside Profile of Flaxseed Extracts and their Antioxidant Capacity

The application of flaxseed extracts as food ingredients is a subject of interest to food technologists and nutritionists. Therefore, the influence of the extraction method on the content and composition of beneficial compounds as well as anti-nutrients is important. In the study, the effects of two solvent extraction methods, aqueous and 60 % ethanolic, on phenolic and cyanogenic glucoside profiles of flaxseed extract were determined and compared. The impact of extracted phenolic compounds on the antioxidant capacity of the extracts was also investigated. Defatted meals from brown and golden flax varieties were used as extraction material. The ethanolic extraction was more selective for phenolics (100.8-131.7 mg g-1) than the aqueous one (11.5-15.7 mg g-1). However, the contribution of particular phenolic compounds to total phenolics was much more dependent on flax variety than extraction method. A strong relationship was observed between both radical scavenging and ferric reducing activity and the content of phenolics (particularly secoisolariciresinol diglucoside). The correlation between extract chelating ability and phenolics was moderate suggesting that other flaxseed compounds are involved in this activity. The extraction method strongly affected cyanogenic glucoside content of flaxseed extracts; the aqueous extraction caused 96 % reduction in cyanogenic glucoside content (0.56-0.62 mmol g-1) when compared to the content in defatted meal (9.1-11.6 mmol g-1). On the contrary, ethanolic extraction resulted in the high cyanogenic glucoside content in the extracts (71-89 mmol g-1). The results reveals that ethanolic extraction gives extracts rich in antioxidant lignans; aqueous extracts have lower antioxidant activity than ethanolic but cyanogenic glucosides are significantly reduced.

Effect of Flaxseed Meals and Extracts on Lipid Stability in a Stored Meat Product

Flaxseeds have been recently in focus due to the antioxidant capacity of some of their compounds. However, there is a lack of easily accessible information concerning their activity against lipid oxidation in food systems. Therefore, the aim of the study was to determine the effect of defatted meals (DFM) and the aqueous extracts (AFE) obtained from brown and golden flaxseeds on lipid oxidation in pork meatballs. Fatty acid composition, peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and cholesterol content were monitored during 6 months of freezer storage. Cholesterol oxidation products were identified and quantified. Both DFM and AFE limited fatty acid and cholesterol oxidation during meatball storage. Their antioxidant effect depended on flax variety (brown or golden) and preparation type (DFM or AFE). Lower level of PV and TBARS, compared with the ones with AFE, were noted in meatballs with DFM. Both DFM and AFE, from the brown seed variety, protect the lipids against oxidation to a higher extent. During the storage, a cholesterol degradation was observed. AFE (particularly from the brown variety) limited changes in cholesterol content. Moreover, they stabilized fatty acid composition of stored meatballs. However, DFM efficiently inhibited cholesterol oxidation.