Ultrasonic disruption of Saccharomyces cerevisiae cells: Relationship between cytoplasm releasing and yeast biomass films properties

JUAN FRANCISCO DELGADO; CARLA INÉS MOYANO; MERCEDES ANA PELTZER; ANDRÉS SALVAY; ORLANDO DE LA OSA; JORGE RICARDO WAGNER

Punta del Este

Congreso; 2º Congreso Iberoamericano de Ingeniería de los Alimentos; 2016

Asociación de Ingenieros Alimentarios del Uruguay

ULTRASONIC CELLS DISRUPTION OF SACCHAROMYCESCEREVISIAE: RELATIONSHIP BETWEEN CYTOPLASM RELEASING AND YEAST BIOMASS FILMSPROPERTIES Delgado,J. F.(1)*, Moyano, C.(1), Peltzer, M.(1), Salvay, A. G.(1), de la Osa, O.(1) y Wagner,J. R.(2) (1)  Laboratoriode Obtención, Modificación, Caracterización y Evaluación de Materiales(LOMCEM), CONICET, Universidad Nacional de Quilmes(2)  Laboratoriode Investigación en Funcionalidad y Tecnología de Alimentos, CONICET,Universidad Nacional de Quilmes. Roque Sáenz Peña 352, Bernal, Buenos AiresProvince, Argentina (B1876BXD) e-mail: *juan.delgado@unq.edu.ar Thematic area:(2) New technologies for applications and innovations in food processing.  Keywords:ultrasonic disruption, biodegradable films, Saccharomyces cerevisiae, particlesize distribution, mechanical properties.  The development of new materials is a trending topicin the field of Materials Science. There are many reasons to look for newsources of biodegradable polymers due to its low environmental impact. In thissense, Saccharomyces cerevisiae cells have demonstrated to be a cheap andmassive source of biopolymers (proteins and polysaccharides). Ultrasonic is anemerging technology to break up microorganisms cells and make available itsbiopolymers for different applications, amongst these the development ofbiodegradable films, which is the aim of this work. Dispersions of S. cerevisiae cells (10 wt%) weretreated by an Ultrasonic homogenizer (US) at 80 W during different times: 5,10, 15, 20, 30 min. A fraction without treatment was prepared and stored. Aftereach treatment, dispersions were characterized by Static light scattering,using a refraction index of 1.4, to observe the particle size distribution andthe protein concentration in the supernatant after centrifugation was analyzedby UV-Vis Spectroscopy at 233 and 224 nm. Results demonstrated that while the UStime exposure increased, the number of small size particles (<1 µm) weregenerated in dispersions. The amount of protein released to the media wassignificant since 5 min of treatment. In addition, dispersions were thermallytreated (90 ºC, 20 min) and again US during 5 minutes. Films were obtained bythe casting method (30 ºC, 50 % r.h.) by pouring dispersions into plastic Petridishes, after the addition of glycerol as a plasticizer (25 %wt/wt dry matter).Performance of the formed films was tested by uniaxial traction and Youngmodulus, tensile strength and elongation at break parameters were compared betweenformulations. Films prepared with 30 min of US presented the best propertiesregarding mechanical behavior.It is possible to conclude that is necessary to reacha high amount cytoplasmatic material to form good quality films and this isrelated to high exposure times of ultrasound.