A potential source of postbiotics: fermentation of WPC by K. marxianus VM005

AMINAHUEL, CARLA A; VICO ANA P; CAVAGLIERI, LILIA R; MONTENEGRO, MARIANA A.

Los cocos

Congreso; XVII Congreso Argentino de Microbiología General; 2022

Sociedad Argentina de Microbiología Genereal

Recently, consumers are showing a growing interest in microbiome health and food products that not only satisfies their nutritional requirements but also has health benefits. This has caused great interest from industries to search for and develop food and ingredients to promote human health. On the other hand, industries must design strategies for the use of by-products generated and give them added value. The dairy industry is one of the most important production sectors, which generates a large quantity of by-products that can be revalorized like whey and whey permeate concentrate (WPC). An interesting option is the fermentation of these by-products by yeast to produce postbiotics. Kluyveromyces marxianus is one of the yeasts found in whey with the ability to use whey for fermentation. Yeasts have diverse applications in the functional food industry as postbiotic producers due to the high value of their components. In this sense, the aim of this work was to evaluate the potential production of postbiotics through the fermentation of WPC with K. marxianus VM005, a native yeast from whey. For this purpose, the strain was initially grown to achieve 107 cells/mL it was centrifuged, and then washed twice with phosphate buffer saline. The biomass was resuspended in the same buffer and used as the initial inoculum. WPC (35% w/w protein) was used as fermentation medium; it was prepared at 4% (w/v) and pasteurized. The process was carried out for 48 h, at 30°C and 200 rpm. Samples were taken at 18, 24, and 48 h. Each sample was inactivated in a bath at 90°C for 10 min and then, lyophilized. WPC medium without inoculum was used as a control. Antioxidant capacity (AOx) and total polyphenols content (TPC) were measured in each sample. All experiments were carried out in triplicate. The AOx was evaluated by deactivation efficiency of the radical cation 2.2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+) expressed as % D/µg powder. The results showed a time-depending significant increase of AOx, from 0.15% at 18 h to 0.23% at 48 h of fermentation. The AOx of WPC was 0.09%. The TPC was evaluated using the Folin-Ciocalteu method and results were expressed in mg equivalents of Gallic acid per gram of powder. The TPC maximum was at 48 h with a significant increase, 57% more TPC than control and, 23% more than the sample at 18 h. The powder at 48 h was chosen to evaluate the AOx capacity equivalent to Trolox by ABTS•+ method (TEAC) and the O2- radical deactivation capacity by the pyrogallol autoxidation method. The latter was expressed as the concentration necessary to inhibit 50% of the O2- radical (IC50). The results showed a TEAC of 0,045 ± 0,002 µmol Trolox/mg powder and an IC50 of 1,71 ± 0,01 mg powder/mL for the O2- radical. These results have demonstrated that it was possible to obtain an ingredient with antioxidant capacity and polyphenol content as a potential postbiotic for the formulation of healthy and functional foods.