Allaoua Achouri

Effect of succinylation on the physicochemical properties of soy protein hydrolysate

Abstract The combined effect of enzymatic hydrolysis of soy protein isolate and the influence of various levels of succinylation on the physicochemical properties of resulting soy protein hydrolysate (SPH) have been studied. The results indicated that proteolysis followed by succinylation resulted in a major soluble protein fraction having a molecular weight of 7 kDa. Depending on the level of modification, succinylation appeared to cause both dissociation of the higher molecular weight fractions (1000 and 400 kDa), and re-association of polypeptides as a result of intermolecular hydrophobic interactions. Surface hydrophobicity (S0) of SPH decreased drastically due to the higher degree of hydrolysis value applied. Additionally, the significant increase in the net charge and elcectrostatic repulsion caused the molecules to expend and undergo conformational changes as reflected by the changes in the hydrophobicity and fluorescence intensity data. Total essential amino acid content was slightly lowered at the highest degree of modification. Low degrees of succinylation improved the in vitro digestibility of the soy protein hydrolysates, and the highest value was observed at 69.5% succinylation.

Analysis of Glabrous Canary Seeds by ELISA, Mass Spectrometry, and Western Blotting for the Absence of Cross-Reactivity with Major Plant Food Allergens

Glabrous (hairless) canary seed belongs to the Poaceae (Gramineae) family and could serve as an alternative source of gluten-free cereal grain. In this study, allergenic cross-reactivities between hairless, dehulled canary seeds (Phalaris canariensis) and major allergenic proteins from gluten, soy, peanuts, tree nuts, sesame, and mustard were studied using commercial enzyme-linked immune sorbent assay (ELISA) kits specific for these target allergens. Mass spectrometry (MS) and immunoblotting were further used to assess for the presence of gluten-specific protein fragments. MS results revealed the likely presence of proteins homologous with rice, oat, corn, carrot, tomato, radish, beet, and chickpea. However, no presence of celiac-related gluten fragments from wheat, rye, barley, or their derivatives was found. Immunoblotting studies yielded negative results, further confirming the absence of gluten in the canary seed samples tested. No cross-reactivities were detected between canary seeds and almond, hazelnut, mustard, peanut, sesame, soy, walnut, and gluten using ELISA.

Correction to Protein-Protein Multilayer Oil-in-Water Emulsions for the Microencapsulation of Flaxseed Oil: Effect of Whey and Fish Gelatin Concentration.

The impact of whey protein isolate (WPI) and fish gelatin (FG) deposited sequentially at concentrations of 0.1, 0.5, and 0.75% on the surface of primary oil-in-water emulsions containing 5% flaxseed oil stabilized with either 0.5% fish gelatin or whey protein, respectively, was investigated. The results revealed that the adsorption of WPI/FG or FG/WPI complexes to the emulsion interface led to the formation of oil-in-water (o/w) emulsions with different stabilities and different protection degrees of the flaxseed oil. Deposition of FG on the WPI primary emulsion increased the particle size (from 0.53 to 1.58 μm) and viscosity and decreased electronegativity (from -23.91 to -11.15 mV) of the complexes. Different trends were noted with the deposition of WPI on the FG primary emulsion, resulting in decreasing particle size and increasing electronegativity and viscosity to a lower extent. Due to the superior tension-active property of WPI, the amount of protein load in the WPI primary emulsion as well as in WPI/FG complex was significantly higher than the FG counterparts. A multilayer emulsion made with 0.5% WPI/0.75% FG exhibited the lowest oxidation among all of the multilayered emulsions tested (0.32 ppm of hexanal) after 21 days, likely due to the charge effect of FG that may prevent pro-oxidant metals to interact with the flaxseed oil.