Effect of the type of substrate on the chemical composition and productivity of a protein concentrate of yeast origin

Abstract

Extracts of Saccharomyces cerevisiae (Sc) yeast were generated using a biotechnological solid-state fermentation method. The organic material used for fermentation consisted of a variety of fibrous substrates of agricultural origin, and their effect on the chemical composition and productivity of cellular biomass generated was evaluated. The substrates studied included the following: wheat straw, WS; barley straw, BS; chili stubble, CS; oat hull, OH and starch powder, SP (control). For incubation with Sc, 2 g of (dry) vegetable substrate were added to 12 mL of cultivation medium. The fermentation time was seven days under aerobic conditions (pH 5, 26ºC). After extraction of the yeast biomass, its chemical composition and productivity were analyzed. The results showed an effect (P≤0.01) of the type of vegetable substrate fermented on the crude protein (CP) and true protein (TP) contents of the yeast biomass. The highest concentration of CP was obtained by fermentation of the control TSP (treatment with the starch powder substrate ) (506.3 g kg -1 DM), followed by the treatment TOH (474.5 g kg -1 DM). The productivity of the yeast biomass was affected by the type of substrate fermented (P≤0.001). The highest value was obtained with TSP (327.10 mg g -1 ), followed by TOH (treatment with the oat hull substrate) (207.08 mg g -1 ). The lowest efficiency was measured in TCS (156.30 mg g -1 ). On the basis of these results, it may be inferred that an extract of high CP can be obtained from yeast (Sc) by the fermentation of fibrous substrates.

Improvement in nutritional quality of fibrous food via in vitro digestion by Aspergillus niger

“…This dose established a substrate-limiting kinetic condition, which was determined by preliminary experiments in our laboratory. Basal input of An to the culture medium was corrected by inoculum incubation in inert material, without organic substrate (Velásquez et al, 2012). The incubation time was 144 h under continuous ventilation (28 °C).…”

“…The biological methods include those based on the use of hydrolytic enzymes and microorganisms, particularly saprophytic fungi with fibrolytic potential (Zafar et al, 1996;Kuhad et al, 1997;Rodrigues et al, 2008;Gaitán-Hernández et al, 2011). These biological methods can improve the nutritional quality of fibrous foods by increasing true protein (TP) content (Velásquez et al, 2012), and improve digestibility by decreasing cell wall content (Kuhad et al, 1997;Villas-Boas et al, 2002). The advantage of biological methods for improving the nutritional quality of these foods over physical and chemical techniques is their low environmental impact, which generate little pollution and require little energy for their application (Basu et al, 2002;Shrivastava et al, 2012).…”

Producción de proteína unicelular de Saccharomyces cerevisiae con granza de arroz e inclusión en cerdos

“…En el proceso de obtención de etanol, se realiza fermentación anaeróbica con el uso de una levadura como la S. cerevisiae, que consume los azucares fermentables hidrolizados a partir del almidón del arroz produciendo alcohol y CO2 como productos del metabolismo final del microorganismo (Gohel y Duan, 2012); aunque el proceso no está enfocado a la obtención de PUC, hay crecimiento celular de la levadura y se recupera en lo que se denomina granos de destilería, los que poseen valores proteicos similares a PUC obtenida de almidones por FL aerobia y bajos niveles de SS usados como sustrato (Velásquez et al, 2012, Aruna et al, 2017. Los granos secos de destilería con solubles (DDGS) de arroz son subproductos del proceso de obtención de etanol, producidos a partir del arroz partido "broken rice", que poseen buenas características nutricionales y son utilizados para la alimentación animal (Gohel y Duan, 2012, Chu-Ky et al, 2016.…”

Effect of substrate on the in vitro protein digestibility of extracts generated by Saccharomyces cerevisiae

“…The total contents of the bioreactors were homogenized by blending (3 min) (Waring 8010BU-CAC33) and filtered through cheesecloth, followed by a second filtration through a steel mesh with a pore size of 100 μm. The filtrate was then centrifuged at 6,500 x g (10 min) at 4 ºC, obtaining a pellet corresponding to the yeast biomass (Velásquez et al, 2012). This protein concentrate was frozen at -32 ºC until the in vitro digestibility of its proteins was assayed.…”

“…Each treatment was corrected with the respective blanks, consisting of incubations of the substrates without inocula (Sc). Furthermore, the basal input of inoculum by incubation of yeast (Sc spores) in the culture medium was corrected using an inert material without organic substrate (Velásquez et al, 2012).…”