ABSTRACT
In the present study, four different combinations of gums, including carrageenan (CG), its binary blends with xanthan gum (XG) or guar gum (GG) in equal ratios, and its ternary blends with XG and GG in three equal ratios, were involved into making partially crystalline emulsions (PCEs), respectively. The freshly prepared emulsions were systematically characterized by rheological property, particle size distribution, microscopic morphology, interfacial property, and intermolecular interactions, and their emulsion stabilities were further evaluated using multiple light scattering technique and storage test. All PCEs stabilized by gum blends (CG + XG, CG + GG, and CG + XG + GG) obtained decreased apparent viscosities at 0.01 s-1 (10.12-25.32 Pa·s), particle sizes (3.12-4.06 µm), as well as interfacial protein concentrations (22.60-27.01 mg/m2), which were much lower than those with single CG (35.98 Pa·s, 6.72 µm, and 47.74 mg/m2, respectively). The microscopic morphology showed that blending CG with XG and/or GG contributed to formation of firmer three-dimensional matrix, thereby preventing the aggregation of fat droplets. Inclusion of XG and/or GG also significantly reduced contribution of hydrophobic interactions from 0.72 to 0.24-0.44 mg/mL. Both multiple light scattering and storage test revealed that emulsion instabilities were mainly manifested as a clarification at the bottom and an agglomeration at the top. PCE-CG + XG + GG exhibited superior stability with low creaming index (6.20 %) and viscosity (1180.0 mPa·s) after three months of storage. The research aims to evaluate the effects of CG and its blends with XG and GG on stability of PCEs, and the results potentially provide valuable information for manufacture of stable PCE foods.
Subject(s)
Plant Gums , Polysaccharides, Bacterial , Carrageenan , Plant Gums/chemistry , Polysaccharides, Bacterial/chemistry , Emulsions/chemistry , Rheology , Viscosity , Particle SizeABSTRACT
The aversive behavior of Caenorhabditis elegans is an important strategy that increases their survival under pathogen infection, and the molecular mechanisms underlying this behavior have been described. However, whether this defensive response occurs in plant-parasitic nematodes (PPNs), which have quite different life cycles and genomic sequences from the model nematode, against biocontrol microbes and affects interspecific interactions in ecological environments remains unclear. Here, we showed that Meloidogyne incognita, one of the most common PPNs, engaged in lawn-leaving behavior in response to biocontrol bacteria such as Bacillus nematocida B16 and B. thuringiensis Bt79. Genomic analysis revealed that the key genes responsible for the aversive behavior of C. elegans, such as serotonin-and TGF-ß-related genes in canonical signaling pathways, were homologous to those of M. incognita, and the similarity between these sequences ranged from 30% to 67%. Knockdown of the homologous genes impaired avoidance of M. incognita to varying degrees. Calcium ion imaging showed that the repulsive response requires the involvement of the multiple amphid neurons of M. incognita. In situ hybridization specifically localized Mi-tph-1 of the serotonin pathway to ADF/NSM neurons and Mi-dbl-1 of the TGF-ß pathway to AVA neurons. Our data suggested that the repulsive response induced by different biocontrol bacteria strongly suppresses the invasion of tomato host plants by M. incognita. Overall, our study is the first to clarify the pathogen-induced repulsive response of M. incognita and elucidate its underlying molecular mechanisms. Our findings provide new insights into interspecific interactions among biocontrol bacteria, PPNs, and host plants.
