Role of light emitting diode (LED) wavelengths on increase of protein productivity and free amino acid profile of Spirulina sp. cultures.

LEDs have specific wavelengths that can positively influence the production of microalga biomass and biomolecules of interest. Filling the gaps in the literature, this study evaluated the effect of different LED wavelengths and photoperiods on protein productivities and free amino acid (FAA) profile of Spirulina sp. LEB 18 cultures. The best protein productivity results were obtained in red and green LED cultures using integral and partial photoperiods, respectively. In these experiments, protein productivities increased 2 and 1.6 times, respectively, compared to the control culture using fluorescent light. Green LEDs in partial photoperiod provided also the highest concentrations of essential and non-essential FAA, about 1.8 and 2.3 times higher, respectively, than control cultures. LEDs showed to be a promising sustainable light source for increasing protein productivity and FAA concentration in Spirulina sp. LEB 18 cultures.

Antibacterial activity of Timsen® (n-alkyl dimethyl benzyl ammonium chloride-40%) in scalding and precooling water in poultry slaughterhouses.

The objective of this study was to evaluate the efficacy of a product based on n-alkyl dimethyl benzyl ammonium chloride-40%, marketed as Timsen®, during scalding and precooling of poultry carcasses in slaughterhouses. To this end, three poultry slaughterhouses (A, B and C) were evaluated. The product was added (200 ppm) to the scalding (58 °C) and precooling water (4 °C), and microbiological analyses were performed of the water and the poultry carcasses before and after Timsen® addition. The product controlled the multiplication of aerobic mesophilic microorganisms, both in the scalding as in the precooling water. In a comparison of carcasses soaked in Timsen®-treated scalding and precooling water with carcasses soaked in untreated water, the count of aerobic mesophilic microorganisms in the later was higher and thermotolerant coliform was not detected in samples of carcasses soaked in Timsen®-treated water. When the scalding and precooling water was not treated with the product, Listeria spp. was isolated from poultry carcasses of two slaughterhouses (A and C), while these microorganisms were not detected when Timsen® was applied. The use of Timsen® in the scalding and precooling water enhanced the safety and control microbial contamination of poultry carcasses.