Review: Effect of Experimental Diets on the Microbiome of Productive Animals.

The microorganisms that inhabit the gastrointestinal tract are responsible for multiple chains of reactions that affect their environment and modify the internal metabolism, their study receives the name of microbiome, which has become more relevant in recent years. In the near future, the challenges related to feeding are anticipated to escalate, encompassing the nutritional needs to sustain an overpopulated world. Therefore, it is expected that a better understanding of the interactions between microorganisms within the digestive tract will allow their modulation in order to provide an improvement in the immune system, feed efficiency or the promotion of nutritional characteristics in production animals, among others. In the present study, the main effects of experimental diets in production animals were described, emphasizing the diversity of the bacterial populations found in response to the diets, ordering them between polygastric and monogastric animals, and then describing the experimental diets used and their effect on the microorganisms. It is hoped that this study will help as a first general approach to the study of the role of the microbiome in production animals under different diets.

Maqui (Aristotelia chilensis (Mol.) Stuntz): A Natural Antioxidant to Improve Quality of Meat Patties.

Aristotelia chilensis is an endemic shrub of the South Pacific with high concentrations of bioactive compounds in its leaves and, therefore, it is highly valued. The effect of Aristotelia chilensis leaf powders (maqui leaf powders; Ma) on the quality and shelf life of beef patties during 7 days of storage was investigated. Five beef patties treatments were prepared: (1) Control without antioxidants (CT); (2) Beef patties with synthetic antioxidants plus color (250 mg/kg) (PL); (3) Beef patties with 500 ppm of maqui leaf powders (Ma500); (4) Beef patties with 1000 ppm of maqui leaf powders (Ma1000); and (5) Beef patties with 2000 ppm of maqui leaf powders (Ma2000). The quality of the beef patties was evaluated on day 0 and day 7 of storage by physicochemical analysis (moisture, ash and lipid content, color, pH, fatty acid profile and lipid oxidation) and organoleptic analysis. The addition of maqui leaf powders did not produce changes in the proximate composition of the beef patties. The pH for all treatments showed a range of 5.50−5.75 and significant differences (p < 0.05) were observed at the beginning and end of storage. The pH of the control beef patties increased during storage while the pH of the beef patties with synthetic and natural antioxidants decreased. Redness (a*) was the color indicator that was mostly affected by the inclusion of 1000 ppm and 2000 ppm powders. High lipid oxidation was observed in control samples on the seventh day of storage due to the high percentage of fat used in the formulation and the absence of any antioxidant. However, the Ma500, Ma1000, and Ma2000 treatments presented the lowest lipid oxidation rates (42.05%, 40.29%, and 43.14%, respectively) in comparison with the synthetic antioxidant (52.23%). This lipid inhibition is related to the strong antioxidant activity (29.75 µg/mL IC50 DPPH) of the maqui leaf powder due to its high content of total polyphenols (148.76 mg GAE/g), mainly characterized by having great amounts of hydroxybenzoic acids (82.5 mg GAE/g), flavonoids (7.1 mg QE/g), and hydroxycinnamic acids (3.7 mg CAE/g). Although minimal variations were observed in some individual fatty acids, and despite the trend to decrease MUFA and increase SFA with the maqui leaf powder addition, these differences were minimal and, according to the nutritional indices results, without any influence on the nutritional quality of the beef patties. The organoleptic analysis showed that the addition of maqui leaf powders did not affect the general acceptability of the new formulations. This study reports for the first time the substitution of synthetic antioxidants with Aristotelia chilensis leaves extract. Based on the results, it can be concluded that this ingredient can be used as an alternative for the production of raw meat products with clean labels.

Antibacterial, kinetics and bacteriolytic properties of silver(I) pyridinedicarboxylate compounds.

Antibacterial properties of silver(I)-pyridinedicarboxylate compounds (with Pyridine-2,3-dicarboxylic(Lutidinic acid), pyridine-2,4-dicarboxylic (Quinolinic acid) and pyridine-2,5-dicarboxylic (Isocinchomeronic acid)) were studied against Escherichia coli, Listeria monocytogenes (ISP-65-08), Salmonella typhi and Staphylococcus aureus (ATCC 25923) using kinetics of grown inhibition, viability assays, minimum inhibitory concentration and optical microscopy. The 3 silver compounds were tested toward UV-radiation in order to characterize their light insensitivity for potential medical devices: UV-radiation curable polymers. Photophysical measurements show remarkable differences toward UV-radiation, which were explained based on their polymeric structures with multiple nature bonds between pyridinedicarboxylic ligands and Ag(I) centers. We found a bacteriolytic effect and differences in the antibacterial efficiency depending on the structure of the complexes and the nature of AgX (X=oxygen and nitrogen) bonds: AgQuinol>AgLutidin>AgIsocinchom.