Effect of temperature on structural configuration and immunoreactivity of pH-stressed soybean (Glycine max) agglutinin.

Soybean agglutinin (SBA) was purified using ammonium sulfate precipitation and liquid chromatography. Purified SBA was used to produce monoclonal antibodies through hybridoma technology. SBA secondary structure was studied using circular dichroism. pH-stressed (pHs 3.0, 7.2, 8.5, and 9.6) SBA physical properties (particle size, ζ-potential, and aggregation temperature) were investigated. Gel electrophoresis (non-native and native) was used to study heat-induced structural configuration changes in SBA. The effect of pH and temperature on the immunoreactivity of SBA was analyzed using enzyme-linked immunosorbent assay and immunoblots probed with two anti-SBA monoclonal antibodies with either linear or conformational epitopes. The hemagglutinating activity of heated SBA was measured by hemagglutination assay. Our results indicated that SBA had the least thermostability at pH 3.0 and the highest at pH 8.5. Temperature-induced structural configuration change on pH-stressed SBA led to immunoreactivity change. Heat-induced (70 and 80 °C) soluble SBA aggregation was proportionally related to hemagglutinating activity reduction.

Investigation of Antioxidant and Cytotoxicity Activities of Chocolate Fortified with Muscadine Grape Pomace.

Muscadine grape pomace and mixed products with chocolate extracts from three muscadine genotypes exhibiting different berry skin colors (black and bronze) were investigated for total phenolic content (TPC), total flavonoid content (TFC), DPPH, FRAP antioxidant activity, and anticancer activity using MDA-MB-468 (MM-468; African American) breast cancer cells. Muscadine berry extracts and mixed products showed cytotoxicity activities of up to 70% against MM-468 breast cancer cells. Cell growth inhibition was higher in 'macerated Floriana' with an IC50 value of 20.70 ± 2.43 followed by 'Alachua' with an IC50 value of 22.25 ± 2.47. TPC and TFC in macerated MGP powder were (1.4 ± 0.14 and 0.45 ± 0.01 GAE/g FW, respectively), which was significantly higher than those in cocoa powder. Data analysis showed a high association between DPPH, FRAP antioxidant activities, and TPC content and a positive high correlation between anticancer activity and antioxidant capacity and between TPC and anticancer activity. The anticancer and antioxidant effects of muscadine grape pomace and chocolate extracts are attributed to the TPC of extracts, which showed a stronger positive correlation with growth inhibition of African American breast cancer cells. This study would be of great value for food industries as well as other manufacturers who are interested in new food blends.

Composition, structural configuration, and antigenicity of Atlantic cod (Gadus morhua) tropomyosin.

Tropomyosin, a myofibrillar muscle protein, has been recognized as a finfish allergen. In this study, tropomyosin from Atlantic cod fillets (Gadus morhua, CTM) was purified using a two-step purification strategy (isoelectric precipitation and anion-exchange chromatography). CTM structural configuration in two sample matrices (impure and pure) were elaborated using different polyacrylamide gel electrophoresis (native, non-reducing, and reducing PAGE). Their corresponding immunoblots were conducted to investigate CTM antigenicity under three conditions. Overall, CTM retained solubility, integrity, and antigenicity after heat treatment. Three CTM monomeric α-type isoforms (33 kDa) were identified using two-dimensional PAGE. Under native condition, the vast majority of CTM existed in the disulfide-reduced dimeric form (66 kDa). Under non-reducing condition, sodium dodecyl sulfate (anionic surfactant) broke CTM dimers, leaving monomers and disulfide-induced tetramers. Under reducing condition, ß-mercaptoethanol (thiol reducing agent) dissociated disulfide-linked CTM tetramers (132 kDa) into monomers (33 kDa). CTM retained antigenicity regardless of structural configuration under different conditions.

Aquatic food animals in the United States: Status quo and challenges.

This review summarizes (1) the U.S. status quo for aquatic food animal production and marketing; (2) major food safety and quality issues/concerns for aquatic food animals in the United States, including fish misbranding, finfish/shellfish allergies, pathogens, toxins and harmful residues, microplastics, and genetically engineered salmon; and (3) various U.S. regulations, guidances, and detection methods for the surveillance of fishery products. Overall, fish misbranding is the biggest challenge in the United States due to the relatively low inspection rate. In addition, due to the regulatory differences among countries, illegal animal drugs and/or pesticide residues might also be identified in imported aquatic food animals. Future regulatory and research directions could focus on further strengthening international cooperation, enhancing aquatic food animal inspection, and developing reliable, sensitive, and highly efficient detection methods.

Effects of casein micellar structure on the stability of milk protein-based conjugated linoleic acid microcapsules.

The effects of casein micellar structure on the stability of milk protein-based conjugated linoleic acid (CLA) microcapsules were investigated. CLA emulsions were prepared with milk protein concentrates (MPC) or a mixture of whey protein isolates (WPI) and sodium caseinate (SC). Larger droplet sizes and wider size distributions were observed for MPC-CLA emulsions, where the varied sizes and heterogeneous protein particles with different rigidity discontinuously adsorbed on the oil droplets. Aggregated oil droplets with porous walls were found on the inner surface of MPC-CLA spray-dried powders. These microcapsules also had lower encapsulation efficiency and unfavorable oxidative stability. For MPC-CLA, 17% of the CLA remained after 45 days at 35 °C, while ∼80% was retained for the WPI+SC-CLA microcapsules. The adverse effect of the casein micellar structure suggested that modification of casein micelles will be needed to improve the efficiency and chemical stability of such microcapsules.