Temperature Dependent Antimicrobial Activity of Menhaden Fish Oil in vitro and on Pet Food Kibbles Against Salmonella spp.

Fish oil inclusion into a dry pet food provides a source of long-chain omega-3 fatty acids. Polyunsaturated fatty acids (PUFA) in fish oil have antibacterial activity against various foodborne pathogens such as Salmonella and pathogenic Escherichia coli. The purpose of this study was to determine the effect of temperature applied to dry pet food kibbles on the antimicrobial activity of Menhaden fish oil against Salmonella spp. Sterile Menhaden oil was inoculated with ~8 logs of Salmonella cocktail (~3 % moisture; S. Enteritidis , Heidelberg, and Typhimurium) and incubated at 25°C, 37°C, and 45°C. Microbiological evaluation of the water phase was done after 2h on TSA agar. Sterile kibbles were coated with fish oil (7.0 % w/w). Canola oil coating was kept as a control. One hour after coating, the kibbles were inoculated with ~9 logs of Salmonella and incubated at their respective temperature. The microbiological evaluation was conducted at 0h, 2h, 6h, 12h, and 24h. The oil phase of the fish oil system was negative for Salmonella after 2h of incubation and confirmed by enrichment and PCR. From the water phase, 8.1 and 7.3 logs were recovered at 25°C and 37°C respectively and no Salmonella was detected at 45°C. On the kibble, Menhaden oil had higher antimicrobial ( p ≤ 0.05) activity after 12h at 25°C, and throughout the experiment at 37°C. At 45°C, the fish oil had a superior antimicrobial activity against Salmonella cocktail after 2h. When the fish oil alone was compared at different temperatures a higher antimicrobial activity was observed at 37°C and 45°C across all time points. The results indicate antimicrobial activity of the Menhaden oil increases with temperature. This is an important finding to the pet food industry; wherein a higher fat holding temperature (~ 45ºC) and the application process may help mitigate Salmonella on extruded kibbles.

Characterization of Mice Ubiquitously Overexpressing Human 15-Lipoxygenase-1: Effect of Diabetes on Peripheral Neuropathy and Treatment with Menhaden Oil

To rigorously explore the role of omega-3 polyunsaturated fatty acids (PUFA) in the treatment of diabetic peripheral neuropathy (DPN), we have created a transgenic mouse utilizing a Cre-lox promoter to control overexpression of human 15-lipoxygenase-1 (15-LOX-1). In this study, we sought to determine the effect of treating type 2 diabetic wild-type mice and transgenic mice ubiquitously overexpressing 15-LOX-1 with menhaden oil on endpoints related to DPN. Wild-type and transgenic mice on a C57Bl/6J background were divided into three groups. Two of each of these groups were used to create a high-fat diet/streptozotocin model for type 2 diabetes. The remaining mice were control groups. Four weeks later, one set of diabetic mice from each group was treated with menhaden oil for twelve weeks and then evaluated using DPN-related endpoints. Studies were also performed using dorsal root ganglion neurons isolated from wild-type and transgenic mice. Wild-type and transgenic diabetic mice developed DPN as determined by slowing of nerve conduction velocity, decreased sensory nerve fibers in the skin and cornea, and impairment of thermal and mechanical sensitivity of the hindpaw compared to their respective control mice. Although not significant, there was a trend for the severity of these DPN-related deficits to be less in the diabetic transgenic mice compared to the diabetic wild-type mice. Treating diabetic wild-type and transgenic mice with menhaden oil improved the DPN-related endpoints with a trend for greater improvement or protection by menhaden oil observed in the diabetic transgenic mice. Treating dorsal root ganglion neurons with docosahexanoic acid but not eicosapentaenoic acid significantly increased neurite outgrowth with greater efficacy observed with neurons isolated from transgenic mice. Targeting pathways that will increase the production of the anti-inflammatory metabolites of omega-3 PUFA may be an efficacious approach to developing an effective treatment for DPN.

Protection of menhaden oil from oxidation in Pickering emulsion-based delivery systems with α-lactalbumin-chitosan colloidal nanoparticle

In this study, α-lactalbumin-chitosan (ALA-CHI) colloidal nanoparticles were spontaneously formed mainly through electrostatic interactions for stabilizing Pickering emulsion. The film of ALA-CHI colloidal nanoparticles had more hydrophobic surface in nature...