Effect of phosphatase/transglutaminase treatment on molar mass distribution and techno-functional properties of sodium caseinate

Effect of protein-glutaminase on the texture, rheology, microstructure and sensory properties of skimmed set-type yoghurt

The effects of enzymatic deamidation by protein-glutaminase (PG) on the texture, rheology, microstructure, and sensory properties of skimmed set-type yoghurt were studied. The proportion of small-particle size milk protein micelles (10-50 nm) increased significantly from 0 to 99.39% after PG deamidation. Cryo-SEM results revealed that PG-treated yoghurt had a denser and less open 3D structure. PG was effective at inhibiting post-acidification during storage at 4 ℃. The water holding capacity of PG-treated yoghurt (0.12 U·mL-1) increased by more than 15%. The fluidity and viscosity of yoghurt were significantly improved with increasing PG dose. Sensory evaluation revealed that PG (0.06 U·mL-1) significantly improved the smoothness and creaminess of skimmed set-type yoghurt, which corresponded to the pastiness in texture. In summary, PG can effectively address the problems of post-acidification, gel fracture, and flavors change in skimmed set-type yoghurt, providing new applications for PG in the food industry.

Effects of Texture Modifiers on Physicochemical Properties of 3D-Printed Meat Mimics from Pea Protein Isolate-Alginate Gel Mixture

Meat mimics were prepared from pea protein isolate-alginate gel via 3D printing. The texture of 3D-printed meat mimics was modified by incorporating transglutaminase (TGase) or κ-carrageenan (κc) at 0.3, 0.6 or 0.9% (w/w) into printing material prior to 3D printing. Rheological properties of modified printing material were measured; results were used to support 3D printing results. Textural properties of raw and cooked meat mimics were determined and compared with those of selected animal meats, namely, pork tenderloin, chicken breast, salmon meat and Spanish mackerel. Cooking losses of meat mimics were also determined. G', G″ and tan δ of TGase-modified material were not significantly different from those of the control. In contrast, increasing κc content resulted in increased G' and G″; tan δ of all κc-modified samples decreased from that of the control. Addition of TGase at 0.9% into printing material increased the hardness of raw meat mimics, while κc at 0.9% increased hardness of cooked meat mimics. Raw meat mimics treated with 0.9% TGase exhibited texture closest to raw salmon. Texture of cooked meat mimics treated with 0.9% κc was closest to that of cooked salmon. TGase-treated meat mimics tended to experience lower cooking losses, while κc-treated meat mimics exhibited an opposite trend.

Industrial Waste-Derived Nanoparticles and Microspheres Can Be Potent Antimicrobial and Functional Ingredients

Rapeseed oilcake or press-cake is generated as bulk waste during oil extraction from oilseeds. Owing to its high protein content, further processing of oilcakes into vegetable protein generates large quantities of fibrous residue (“oil-and-protein” spent meal) as by-product, which currently has very limited practical utility. Here, we report hydrothermal carbonization of this industrial waste to convert it into carbon nanoparticles, bestowed with multitude of functionalities. We demonstrate that these nanoparticles can be assembled into micrometer-sized spheres when precipitated from water by acetone. These microspheres, with their added feature of hemocompatibility, can be potentially utilized as an encapsulation vehicle for the protection of thermolabile compounds (such as protein); however, the secondary and tertiary features of the protein were marginally perturbed by the encapsulation process. The synthesized carbon nanoparticle was found to be an effective biocidal agent, exhibiting bacterial cellular damage and complex formation with the bacterial plasmid (evident from ethidium bromide exclusion assay), which are critical for cell survival. The results show the ability to convert industrial biowaste into useful nanomaterials for use in food industries and also suggest new scalable and simple approaches to improve environmental sustainability in industrial processes.

Physicochemical and functional properties of rapeseed protein isolate: influence of antinutrient removal with acidified organic solvents from rapeseed meal

The presence of antinutritional constituents in rapeseed protein products (RPI), such as polyphenols, phytates, allyl isothiocyanates, and glucosinolates, is a formidable constraint. The effect of antinutrient removal from rapeseed meal with an organic solvent mixture (methanol/acetone, 1:1 v/v, combined with an acid (hydrochloric, acetic, perchloric, trichloroacetic, phosphoric)) on the physicochemical and functional properties of RPI was investigated. The extraction resulted in a substantial reduction of antinutrients from RPI, especially polyphenols and phytates, with concomitant decreases in protein yield and solubility. Treatment harbored significant improvement in the degree of whiteness, which was highest in the perchloric acid case. Surface hydrophobicity and free sulfhydryl group of RPI changed considerably, with perchloric acid-treated samples showing higher values, whereas the disulfide content remarkably increased in trichloroacetic acid- and phosphoric acid-treated samples, signifying aggregation. Intrinsic emission fluorescence and FTIR spectra showed significant changes in proteins' tertiary and secondary conformations, and the changes were more pronounced in samples treated with higher concentrations of acids. No appreciable alteration appeared among the electrophoretic profiles of proteins from pristine meal and those treated with lower levels of acids. Interfacial surface properties of proteins were variably improved by the solvent extraction, whereas the converse was true for their extent of denaturation. The results suggest that the physicochemical and conformational properties of RPI are closely related to its functional properties.

Low-salt restructured fish products from Atlantic mackerel (Scomber scombrus) with texture resembling turkey breast

Atlantic mackerel (Scomber scombrus) is a pelagic and migratory species that is usually caught with other fish as bycatch. The aim of this work was to obtain low-salt restructured fish products from Atlantic mackerel resembling turkey breast using transglutaminase (0.2 U/g) as binder. NaCl concentration (0-20 g/kg), temperature (25-40 °C) and time of incubation (30-90 min) were assayed. The texture parameters (Warner-Bratzler force and Warner-Bratzler work) and expressible water were compared to those of turkey breast. Mathematical models were obtained to determine the effect of these variables on the texture of Atlantic mackerel restructured products. Optimal conditions to obtain a similar texture than turkey breast were found. The overall optimization point out that the treatment at 31.8 °C for 63.35 min using a NaCl concentration of 8.45 g/kg allowed to obtain restructured products from Atlantic mackerel with texture and expressible water similar to those of turkey breast. Color parameters (L*, a* and b*) of the product were also similar to those of turkey breast. The results showed the feasibility of producing low-salt restructured products from Atlantic mackerel resembling turkey breast using transglutaminase.