Aktivnost zgrušavanja mlijeka i primarna proteoliza liofiliziranog ekstrakta cvijeta artičoke (Cynara scolymus L.)

Research background. A few studies have investigated Cynara scolymus enzymes as a substitute for calf rennet in cheese making. They used aqueous extracts prepared by maceration of plant material and stored by freezing. However, it was indicated that lyophilisation is a better alternative to preserve the coagulant properties of plant extracts over a longer period of time, as it is a more controllable, stable and hygienic alternative with a better shelf life that is easier to transport, store and standardise. Experimental approach. We obtained a lyophilised extract of mature artichoke flowers, named CS, which was characterised for its milk-clotting properties at different pH and temperatures. In addition, the potential yield, whey composition and the primary hydrolysis profile of caseins by urea-polyacrylamide gel electrophoresis (PAGE) of mini curds prepared with different doses of coagulant were determined. Results and conclusions. The lyophilised extract was able to hydrolyse casein and showed stable proteolytic activity at pH=6.4 and 37 °C for 50 min, which decreased when the process temperature was increased to 41 and 45 °C and was lost at 70 °C. On the other hand, milk-clotting activity increased significantly (p<0.001) when the temperature increased from 37 to 45 °C and the pH of the milk decreased from 6.8 to 5.8. Potential yield ​​between 10 and 17 % was obtained for the mini curds prepared with the lyophilised artichoke extract, and the casein degradation pattern obtained by urea-PAGE was similar to that of the commercial coagulant. Novelty and scientific contribution. On a laboratory scale, our work has shown that the lyophilised artichoke extract has sufficient proteolytic and coagulant activity to be used as a milk coagulant, i.e. plant rennet, in cheese making as an alternative to animal rennet. As this extract is lyophilised, it has the advantage of being a better alternative in terms of preservation and shelf-life. It offers an innovative way to diversify cheese products and appeal to consumers with different dietary preferences and needs.Pozadina istraživanja. U nekoliko je istraživanja ispitana primjena enzima dobivenih iz artičoke (Cynara scolymus) kao zamjena za teleće sirilo u proizvodnji sira. U njima su korišteni vodeni ekstrakti dobiveni maceracijom biljnog materijala te skladišteni zamrzavanjem. Međutim, pokazalo se da se liofilizacijom bolje očuvaju koagulacijska svojstva biljnih ekstrakata tijekom duljeg skladištenja, jer ih je jednostavnije kontrolirati, održati stabilnima i higijenski ispravnima, a mogu se i dulje vrijeme skladištiti te lakše distribuirati i standardizirati. Eksperimentalni pristup. U ovom smo radu pripravili liofilizirani ekstrakt cvijeta zrele artičoke, te opisali njegova svojstva zgrušavanja mlijeka pri različitim pH-vrijednostima i temperaturama. Osim toga, određeni su mogući prinos, sastav sirutke i uzorak razgradnje kazeina u grušu pripremljenom u malim porcijama s različitim količinama sredstva za koagulaciju, ispitanom elektroforezom na poliakrilamidnom gelu s dodatkom uree. Rezultati i zaključci. Liofilizirani ekstrakt je razgradio kazein i imao stabilnu proteolitičku aktivnost pri pH-vrijednosti od 6,4 i temperaturi od 37 °C tijekom 50 min, koja se smanjila pri porastu temperature na 41 i 45 °C, a potpuno nestala pri 70 °C. Nasuprot tome, aktivnost zgrušavanja mlijeka se bitno povećala (p<0,001) pri porastu temperature s 37 na 45 °C i padu pH-vrijednosti mlijeka sa 6,8 na 5,8. Mogući prinos gruša pripremljenog u malim porcijama pomoću liofiliziranog ekstrakta artičoke bio je od 10 do 17 %, a uzorak razgradnje kazeina određen elektroforezom na poliakrilamidnom gelu s dodatkom uree bio je sličan uzorku dobivenom primjenom komercijalnog koagulanta. Novina i znanstveni doprinos. Naše istraživanje provedeno u laboratorijskim uvjetima pokazalo je da liofilizirani ekstrakt artičoke ima dovoljno veliku proteolitičku aktivnost i sposobnost koagulacije, pa se može upotrijebiti kao sredstvo za zgrušavanje mlijeka, odnosno u proizvodnji sira kao koagulant biljnog podrijetla, umjesto sirila životinjskog podrijetla. Prednost liofiliziranog ekstrakta je u tome što bolje zadržava koagulacijska svojstva i može se dulje vrijeme skladištiti. Osim toga, pruža inovativnu mogućnost proizvodnje različitih vrsta sireva, što može biti zanimljivo potrošačima koji imaju različite prehrambene potrebe i navike

Importance of virtual resources in pandemic times: The Analytical Chemistry I course at UNNOBA as a case study

Las nuevas exigencias en la educación superior se centran en la mejora del proceso educativo. En tal sentido, la integración de las TIC facilita aspectos relacionados con la mejora del trabajo individual, la autonomía del alumnado, la facilidad para el desarrollo de trabajos en equipo y colaborativos, la posibilidad de modificar y adaptar los métodos de evaluación y la interacción entre el profesorado y el alumnado.El objetivo de este trabajo es relatar cómo ha sido atravesar un proceso acelerado desde lo presencial a lo virtual, y su impacto positivo no sólo en el cuerpo docentesino también en los alumnos. El trabajo será abordado desde tres ejes: la importancia de la plataforma digital, la metodología llevada a cabo en las clases virtuales y la forma de evaluar a los alumnos.Concluimos que la pandemia aceleró un proceso que inexorablemente debía ocurrir y que nos llevó a replantearnos la forma de enseñar, acompañada por el uso de los TIC. En esta nueva modalidad el alumno asume un rol protagónico en el proceso de aprendizaje y el docente necesita disponer de nuevas herramientaspara adaptarse. En tal sentido, resulta fundamental el apoyo de las instituciones con herramientas y formación continua.The new demands in higher education focus on improving the educational process. In this sense, the integration of ICT facilitates aspects related to the improvement of individual work, the autonomy of students, the ease of developing team and collaborative work, the possibility of modifying and adapting evaluation methods and the interaction between teachers and students. The objective of this work is to relate what it has been like to go through an accelerated process from the face-to-face to the virtual, and its positive impact not only on the teaching but also on the students. This work will be approached from three axes: the importance of the digital platform, the methodology carried out in the virtual classes and the way to evaluate the students. We conclude that the pandemic accelerated a process that inexorably had to occur and that led us to rethink the way of teaching, accompanied by the use of ICT. In this new modality the student assumes a leading role in the learning process and the teacher needs to have new tools to adapt. In this sense, the support of institutions with tools and continuous training is essential.Fil: Crosetti, Valentina. Universidad Nacional del Noroeste de la Provincia de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Caggiano, Claudia Gabriela. Universidad Nacional del Noroeste de la Provincia de Buenos Aires; ArgentinaFil: Casella, Mónica Laura. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Noroeste de la Provincia de Buenos Aires; Argentin

Importance of virtual resources in pandemic times. The Analytical Chemistry I course at UNNOBA as a case study

Las nuevas exigencias en la educación superior se centran en la mejora del proceso educativo. En tal sentido, la integración de las TIC facilita aspectos relacionados con la mejora del trabajo individual, la autonomía del alumnado, la facilidad para el desarrollo de trabajos en equipo y colaborativos, la posibilidad de modificar y adaptar los métodos de evaluación y la interacción entre el profesorado y el alumnado. El objetivo de este trabajo es relatar cómo ha sido atravesar un proceso acelerado desde lo presencial a lo virtual, y su impacto positivo no sólo en el cuerpo docente sino también en los alumnos. El trabajo será abordado desde tres ejes: la importancia de la plataforma digital, la metodología llevada a cabo en las clases virtuales y la forma de evaluar a los alumnos. Concluimos que la pandemia aceleró un proceso que inexorablemente debía ocurrir y que nos llevó a replantearnos la forma de enseñar, acompañada por el uso de los TIC. En esta nueva modalidad el alumno asume un rol protagónico en el proceso de aprendizaje y el docente necesita disponer de nuevas herramientas para adaptarse. En tal sentido, resulta fundamental el apoyo de las instituciones con herramientas y formación continua.The new demands in higher education focus on improving the educational process. In this sense, the integration of ICT facilitates aspects related to the improvement of individual work, the autonomy of students, the ease of developing team and collaborative work, the possibility of modifying and adapting evaluation methods and the interaction between teachers and students. The objective of this work is to relate what it has been like to go through an accelerated process from the face-to-face to the virtual, and its positive impact not only on the teaching but also on the students. This work will be approached from three axes: the importance of the digital platform, the methodology carried out in the virtual classes and the way to evaluate the students. We conclude that the pandemic accelerated a process that inexorably had to occur and that led us to rethink the way of teaching, accompanied by the use of ICT. In this new modality the student assumes a leading role in the learning process and the teacher needs to have new tools to adapt. In this sense, the support of institutions with tools and continuous training is essential.Facultad de Informátic

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements