Title Ultrazvučno potpomognuta ekstrakcija polifenolnih spojeva iz taloga kave Title (english) Ultrasonically assisted extraction of polyphenolic compounds from coffee residue Author Mislav Humski Mentor Jana Šic Žlabur (mentor)Committee member Jana Šic Žlabur (predsjednik povjerenstva)Committee member Marko Petek (član povjerenstva)Committee member Neven Voća (član povjerenstva)Granter University of Zagreb Defense date and country 2023-09-27, Croatia Scientific / art field, BIOTECHNICAL SCIENCES Abstract Kava se kao napitak priprema prelijevanjem vruće vode preko samljevenih, prethodno prženih sjemenki (zrna) biljke kavovac (Coffea arabica L.), a danas je jedan od najpopularnijih napitaka diljem svijeta. Prilikom pripreme kave zaostaje velika količina organskog ostatka, taloga kave. S obzirom kako je zrno kave općenito bogato različitim fitokemikalijama, posebice polifenolnim spojevima, ostatak koji zaostaje nakon pripreme kave, potencijalno predstavlja bogat izvor bioaktivnih spojeva značajne antioksidacijske aktivnosti. Takav organski ostatak umjesto da se zbrinjava kao biootpad pokazuje veliki potencijal oporabe. U suvremenim procesnim tehnologijama danas se sve više upotrebljavaju zelene tehnologije čiji je glavni cilj upotrebe smanjen negativni utjecaj na okoliš i zdravlje ljudi. Jedna od takvih tehnologija je i ultrazvuk visokog intenziteta, a koji pokazuje niz prednosti od kojih valja izdvojiti znatno skraćeno vrijeme izolacije spojeva te veći prinos istih. Cilj ovog rada bio je utvrditi utjecaj ultrazvučno potpomognute ekstrakcije (sustav sonde i kupelji) na sadržaj polifenolnih spojeva i antioksidacijski kapacitet ekstrakata od taloga kave. Uzorci za testiranje ultrazvučno potpomognute ekstrakcije pripremljeni su iz taloga kave (5 g) sakupljenog iz objekta za posluživanje hrane prilikom čega je kao otapalo varirana koncentracija etanola: 50 i 80 % (v/v). Variran je i način ekstrakcije, klasični tretman i ekstrakcija potpomognuta ultrazvukom visokog intenziteta. Kod ekstrakcije potpomognute ultrazvukom variran je tip uređaja, sonda i kupelj, vrijeme tretmana (5 i 10 min) te u tretmanu sondom amplituda: 20, 40 i 60 %. Najviše vrijednosti ekstrahiranih polifenolnih spojeva utvrđene su u ekstraktima tretiranima sondom pri amplitudi od 60 % i uz upotrebu 50 %-og etanola u vremenskom trajanju od 10 minuta. Također, utvrđeno je da općenito svi uzorci ekstrakata od taloga kave imaju visok antioksidacijski kapacitet, a prilikom čega ABTS metodom utvrđen najviši kapacitet za uzorke tretirane klasično, a FRAP metodom za uzorke tretirane ultrazvučnom sondom pri amplitudi od 20 %, uz upotrebu 50 %-og etanola u vremenskom trajanju od 5 minuta. Iz navedenog može se zaključiti kako tretman ultrazvučnom sondom visokog intenziteta ima pozitivan utjecaj na ekstrakciju polifenolnih spojeva iz taloga kave. Konačno, može se utvrditi da su etanolni ekstrakti od taloga kave bogat izvor specijaliziranih metabolitima prilikom čega se može zaključiti da se radi o potencijalno nutritivno vrijednom nusproizvodu za daljnju oporabu.
Abstract (english) The beverage coffee is prepared by pouring hot water over ground, previously roasted seeds (beans) of the coffee plant (Coffea arabica L.) and is one of the most popular beverages in the world today. When coffee is prepared, a significant amount of organic residue, coffee sludge, is left behind. Since coffee beans are generally rich in various phytochemicals, especially polyphenolic compounds, the residue remaining after coffee preparation may represent a rich source of bioactive compounds with significant antioxidant activity. Rather than disposing of such organic residues as biowaste, they offer great potential for reuse. Today's processing technologies are increasingly using environmentally friendly technologies that are primarily aimed at reducing negative impacts on the environment and human health. One of these technologies is high-intensity ultrasound, which offers several advantages, including significantly reduced time for compound isolation and higher yield. The objective of this study was to determine the effects of ultrasound-assisted extraction (probe and bath system) on the polyphenolic compound content and antioxidant capacity of coffee sludge extracts. Samples for ultrasound-assisted extraction testing were prepared from coffee sludge (5 g) collected from a food service establishment and spiked with different ethanol concentrations: 50 and 80% (v/v). The extraction method was also varied, with classical treatment and high-intensity ultrasound-assisted extraction. For ultrasound-assisted extraction, the type of device, probe and bath, treatment time (5 and 10 minutes), and probe treatment were varied with amplitudes of 20, 40, and 60%. The highest levels of extracted polyphenolic compounds were found in extracts treated with the probe with an amplitude of 60% and using 50% ethanol for a duration of 10 minutes. It was also found that all coffee sludge extract samples generally had high antioxidant capacity, with the highest capacity observed in samples conventionally treated with the ABTS method and in samples treated with the ultrasonic probe at an amplitude of 20% and using 50% ethanol for 5 minutes with the FRAP method. It can be concluded that treatment with a high-intensity ultrasonic probe has a positive effect on the extraction of polyphenolic compounds from coffee sludge. Finally, it can be concluded that ethanol extracts from coffee sludge are a rich source of specialized metabolites, suggesting that they are a potentially valuable nutritional by-product for further utilization.
Keywords
talog kave
ultrazvučna sonda
ultrazvučna kupelj
polifenolni spojevi
antioksidacijski kapacitet
Keywords (english)
spent coffee grounds
ultrasound probe
ultrasound bath
polyphenols
antioxidant capacity
Language croatian URN:NBN urn:nbn:hr:204:185836 Study programme Title: Renewable energy sources in agriculture Type of resource Text File origin Born digital Access conditions Open access Terms of use Created on 2023-11-15 13:32:38
