Provider: - Institution: Josip Juraj Strossmayer University of Osijek. FACULTY OF FOOD TECHNOLOGY. Department of Process Engineering. Sub-department of Modelling, Optimisation and Automatisation. - ...Data provided by Europeana Collections- Fizikalno-kemijska i druga svojstva piva mogu biti izložena promjenama tijekom skladištenja, što pivo čini manje atraktivnim do tržišno neupotrebljivim. Cilj ovog istraživanja bio je statističkim analizama i metodama te matematičkim modelima opisati značajne promjene fizikalno-kemijskih svojstava svijetlog lager piva uskladištenoga tijekom šest mjeseci u različitoj ambalaži staklena ambalaža, PET (polietilen-tereftalat), limenke i bačve. Značajnije promjene tijekom skladištenja su zabilježene za vrijednosti: boje (CL), stabilnosti pjene (FO), otopljenog kisika (DO) i bistroće/mutnoće (HZ) piva, te lako hlapljivih komponenti: acetaldehida (ACE), dimetil sulfida (DMS), diacetila (DIA) i pentanodiona (PEN). Dat je prikaz usporedbe sličnosti promjena ukupnih analiziranih fizikalno-kemijskih svojstava i sastava piva (lako hlapljive komponente) u različitoj ambalaži preko koeficijenta korelacije (r) iz kojega je vidljivo da je najveća sličnost ukupnih promjena između piva u staklenoj ambalaži i bačvama. Najveće i najintenzivnije promjene zabilježene su kod piva u PET ambalaži. Promjene fizikalno-kemijskih svojstava piva koje su pokazale najveće varijabilnosti vrijednosti tijekom skladištenja, a i najznačajniji su pokazatelji fizikalno-kemijskih svojstava, opisane su modelima polinomne regresije (PR) s koeficijentima determinacije \R^{2}\ = 1. Model je validiran (svijetlo lager pivo u PET ambalaži) pri čemu koeficijent korelacije (r) potvrđuje sličnost promjene za vrijednosti boje (CL), r = 0,99, stabilnosti pjene (FO), r = 0,94, bistroće (HZ), r = 0,98 i gorčine (BI), r = 0,59, između izmjerenih vrijednosti i vrijednosti dobivenih primjenom polinomnog modela.- General properties of beer are subject to change while in storage, which makes the beer less attractive and even unmarketable. The aim of this research was to describe any significant changes in lager stored in different packaging glass bottles, PET (polyethylene terephtalate), cans, kegs by using mathematical models and statistical analysis. The data were collected during a period of six months and it shows significant changes in color (CL), foam (FO), dissolved oxygen (DO), haze (HZ), and easily evaporating components: acetaldehyde (ACE), dimethyl sulphide (DMS), diacetyl (DIA), and pentanedione (PEN). This paper presents a similarity comparison of significant changes using the correlation coefficient (r) in overall analysis of physicochemical properties and structure of beer in different packaging. The most significant changes are recorded in beer stored in PET. The properties of beer, which show the highest level of variability during storage are described using polynomial regression (PR) models with a coefficient of determination, \R^{2}\ = 1. The model is validated (lager in PET packaging) while the correlation coefficient (r) confirms a similarity in changes for color (CL), r = 0.99, foam (FO), r = 0.94, haze (HZ), r = 0.98, and bitterness (BI), r = 0.59, between the measured values and the calculated polynomial values.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Tajna glazbe Davidović, Dalibor
Arti musices,
05/2014, Letnik:
45, Številka:
1
Paper
Odprti dostop
Misao Ivana Fochta neprestance kruži oko onoga što je nazivao tajnom glazbe. Pokušavajući je imenovati, filozof se nalazi u paradoksalnoj poziciji: rastumačena, tajna glazbe neopazice mu izmakne, ...otkrije mu se prikrivajući se u isti mah, i tako ga odvede upravo na onaj put što ga je želio ostaviti za sobom. Članak evocira četiri međusobno povezana prizora ovoga zbivanja.
Provider: - Institution: - Data provided by Europeana Collections- Senzorne karakteristike vina Plavca malog često uključuju negativna svojstva gorčine okusa i
astrigentnosti nezrelih tanina što je ...dijelom posljedica pogrešnog roka berbe grožđa. S
tehnološkog stajališta, sastav bobica u trenutku berbe od presudne je važnosti za
proizvodnju visokokvalitetnih crnih vina. Tradicionalno odluka o berbi se donosi na temelju
sadržaja šećera, ukupnih kiselina i pH-vrijednosti, a koji ukazuju samo na stupanj zrelosti
pulpe (tehnološka zrelost), dok nam stupanj zrelosti kožice i sjemenki (fenolna zrelost) ostaje
nepoznat. Grožđe ubrano temeljem osnovnih parametara ne garantira fenolnu dozrelost pa
takva vina mogu imati loša senzorna svojstva. Cilj ovog istraživanja je bio procijeniti zrelost
grožđa sorte Plavac mali kvantifikacijom osnovnih fizikalno-kemijskih i polifenolnih spojeva u
moštu i vinu. Grožđe je ubrano u četiri različita roka na dvije različite lokacije pri sadržaju
šećera od 17,6 do 21,40 °Brix, a što odgovara vinima sa 9,30 do 12,98 vol. % alkohola.
Polifenolni spojevi su analizirani spektrofotometrijskim i kromatografskim analitičkim
metodama, a intenzitet boje bobica je utvrđen koristeći nedestruktivni CIELab kolorimetrijski
pristup. Identifikacija i kvantifikacija polifenolnih spojeva ekstrakata grožđa (kožice i
sjemenki) i vina je provedena tekućinskom kromatografijom visoke djelotvornosti HPLC-DAD.
Značajnost razlika u sastavu i koncentraciji pojedinih spojeva tijekom četiri roka berbe na
dvije lokacije je testirana dvosmjernom analizom varijance. Rezultati su pokazali da
dozrijevanjem grožđa raste udio ukupnih i pojedinačnih antocijana i flavonola, a smanjuje se
udio monomernih i dimernih flavan-3-ola u kožici. Udio monomernih flavan-3-ola u
sjemenkama se smanjuje, dok udio dimernih spojeva ostaje stabilan neovisno o roku berbe.
Odgoda roka berbe ima značajan utjecaj na polifenolni sastav vina, grožđe ranijih rokova
berbe daje vina siromašna tvarima boje, antocijanima i flavonolima, s visokim udjelom
procijanidin monomernih i dimernih flavan-3-ola. Vina kasnijih rokova berbe su bolje obojena
uslijed veće koncentracije antocijana i flavonola te sadrže veći udio prodelfinidin naspram
procijanidin monomernih jedinica i nižu koncentraciju dimernih flavan-3-ola. Dobiveni rezultati
pokazali su mogućnost procjene zrelosti grožđa preko vanjskih karakteristika, kao što su boja
kožice bobica i sjemenki. Definirani su metaboliti koji najznačajnije utječu na razlike u
sastavu grožđa i vina između četiri različita roka berbe. Obzirom na povezanost vanjskih
svojstava kožice i sjemenke te kemijskih spojeva izrađena je vizualizacija tonske gradacije
boje sjemenki i kožica bobice tijekom četiri različita roka berbe, a koja predstavlja kvalitetni
indikator dozrelosti grožđa Plavca malog.- Plavac Mali is major red grapevine of the Croatian wine industry. The sensory characteristics
of Plavac Mali wine often include negative sensations of bitter taste and astringency of
immature tannins, which is partly due to the wrong date of grape harvest. From a
technological point of view, the composition of berries at the harvest is essential for
production of high quality red wines. Traditionally the decision about harvest was taken
based on sugar content, titratable acidity, and pH that only provide information about pulp
ripeness, while the real degree of skin and seed maturity (phenolic maturity) remains
unknown. The grape harvested based on conventional parameters does not guarantee
phenolic maturation. Review of the similar researches on phenolic maturation, with emphasis
on so far conducted researches on Plavac Mali, project hypothesis and aims are shown in
the introduction chapter. Plavac Mali is late ripening variety and the race to produce high
concentrated wines, as well as uneven nature of the grape berry ripening, and the wrong
harvest timing indicators implies a delay in harvest with the aim of achieving better coloration
and rounded, velvet tannins which often results in unbalanced wines with high alcohol, low
acid content and high pH value. In this research project it is assumed that the specific ratios
of metabolites (sugars, organic acids, phenolic compounds, nitrogen, and potassium) in
grapes of the Plavac Mali of different harvest dates affect the chemical composition and the
production of different types of wine. It is also assumed that the color of the skin and the
seeds during maturation is correlated with the phenolic composition and can therefore be
used as a good indicator of ripeness of Plavac Mali. The aims of this research project were to
characterize grape and wine of Plavac Mali harvested at different technological ripeness,
examine the most suitable, practical maturity parameters (general maturity indexes, total
concentration of phenolic compounds, CIELab and RGB (HSV) variables of the color, HPLC
profiles) and to determine the best time of harvest. Correlation between the concentration of
the phenolic compounds and color development of the grapes was determined, and
visualisation of the colour gradiation of the grape seeds during diferent harvest dates was
made. The second chapter gives an overview of the latest research in the phenollic maturity
of grapes and consequences on the quality of wines. Chapter is organized in five
subdivisions and includes an overview of 198 literature references. The research carried out
by different authors showed that phenolic compounds play an important role in the quality of
red wine, particularly on sensory characteristics of the color, bitterness and astringency. The
production of high quality wines is based on the optimum degree of phenol grape maturity.
The concept of phenolic maturity at the level of the skin and the seed coat during maturation
implies achieving the highest concentration of anthocyanins in the skin with the lowest
extraction of the seeds proanthocyanidins in the total proantocyanidins. Red grape varieties
easily reach the sugar content required for the production of high quality wines in the
Mediterranean climates, but this is not the case with the phenolic compounds. In the last
stage of the grape berry development, the phenolic compounds, especially the anthocyanins
and the proanthocyanidins go through continuous quantitative and qualitative changes, and
the intensity of the same depends on agro-ecological conditions and vineyard practice.
Wines that are produced from unripe berries, whose skins and seeds did not achieve full
phenolic maturity are poor in color, have bitter taste and astringent sensations. Precise
research material and methods used in determination of grape maturity were described in
third chapter. Grape samples were collected during four different harvest dates in two
different collection vineyards, Duilovo and Baštica. Conventional oenological methods
included 7 different analytical methods. Total polyphenolic capacity of the grape berries was
determined through 3 spectrophotometric methods, and the separation of 5 different groups
of polyphenolic compounds was performed with HPLC. Traditional measurements of sugar
content, titratable acidity and pH are very important for the determination of grape ripeness.
During recent years evaluation of the grape color development and the estimation of the skin
and seed ripeness demands application of sophisticated analytical methods, primarily
spectrophotometric, colorimetric, and the methods of the liquid chromatography.
Unfortunately, these methods are not easily available to viticulturists and winemakers and
require knowledge of analytical chemistry and expensive devices. As the wine market
becomes more competitive, precise determination of the harvest date for production of the
specific wine style will become normal in the future. An inexpensive way of determination of
the best harvest date is the combination of traditional analyses and evaluation of the color of
the grape which is possible with the new tool developed in this research project, visualization
of the grape seed color. The fourth chapter consists of 25 tables, 24 graphs and 4 figures.
The results show the significance of influence of four harvest dates and two locations on
changes in the level of the conventional and polyphenolic parameters of grape and wine
Plavac Mali by two-way analysis of variance. Techniques of the multivariate analysis PCA
and Canonical correlation are used to determine the relationships between samples (PCA)
and parameters (Canonical correlation). Significant difference in physiochemical and
polyphenolic profile of grape berries of the four different harvest dates was determined.
Wines produced from grapes of the different harvest dates showed a greater difference in
basic oenological and polyphenolic profile. Comparison of the results of the polyphenolic
profile of Plavac Mali grape and wine demonstrated the opportunity to evaluate maturity of
the grapes by external parameters of color of grape skins and seeds. Due to the relationship
between external properties of the skin and seeds and chemical compounds, visualization of
the tonal gradation of the seed color during four different harvest dates was developed and
the possibility of its use as a quality indicator of maturity of grapes Plavac Mali was
determined. The research questions from hypothesis and raised by analysis were discussed
in the fifth chapter, organized in three subdivisions. The results are compared to latest
researches from this field. The proposed research provides a detailed insight into the
potential of technological maturity of Plavac Mali. Conventional grape maturity indicators (°
Brix, titratable acid and pH) as well as basic quality indicators, allowed a separation of
grapes based on harvest date and/or growing location. However, it is not possible to
correlate these indicators with the phenolic maturity of berries for the production of high
quality wines. Berries of Plavac Mali reached optimal acidity content in th
Provider: - Institution: - Data provided by Europeana Collections- Kraljevina, autohtoni kultivar Prigorja na područje Svetog Ivana Zeline. ima dugu tradiciju uzgoja, međutim uočena je velika ...varijabilnost biotipova unutar populacije. Upravo zbog sve većeg interesa za uzgojem Kraljevine kao i nepostojanje matičnih (selekcioniranih) nasada upućivali su na potrebu klonske selekcije. U postupku selekcije klonova uz osnovne pokazatelje rodnosti i kvalitete grožđa potrebno je istražiti i razinu varijabilnosti klonskih kandidata u sintezi pojedinih grupa kemijskih spojeva (hlapivi aromatski spojevi, polifenolni spojevi, aminokiseline, pojedinačne organske kiseline) koji sudjeluju u formiranju senzornih svojstava vina te definiraju njegovu kvalitetu. Cilj ovog istraživanja bio je utvrditi osnovni kemijski sastav te udio pojedinačnih organskih kiselina, aminokiselina i aromatskih spojeva u moštu i vinima klonskih kandidata kultivara Kraljevine kao i utjecaj soja kvasca na osnovni kemijski sastav, te udio pojedinačnih organskih kiselina, aminokiselina i aromatskih spojeva, te sastav polifenolnih spojeva u vinima klonskih kandidata kultivara Kraljevine. Uz to cilj je bio i definirati senzorna svojstva vina klonskih kandidata kultivara Kraljevina. Dvogodišnje istraživanje 9 klonskih kandidata (VV-438, VV-406,VV-479,VV-486,VV-483,VV-423,VV-360, VV-434,VV-482) provedeno je u moštu i vinu dobivenom od grožđa iz pokusnih vinograda smještenih u Svetom Ivanu Zelini. Tretmani u istraživanju bili su tretman A: vinifikacija korištenjem komercijalnog soja kvasca Anchor VIN13, i tretman B: vinifikacija korištenjem komercijalnog soja kvasca Uvaferm Affinity. Kemijska analiza mošta i vina obuhvatila je određivanje koncentracije šećera refraktometrijski, ukupnu kiselost titracijskom metodom prema O.I.V.-u, pH vrijednost te određivanje pojedinačnih organskih kiselina te aminokiselina tekućinskom kromatografijom visoke djelotvornosti (HPLC). U uzorcima vina provedena je osnovna fizikalno-kemijska analiza vina prema metodama O.I.V., pojedinačni polifenoli analizirani su primjenom tekućinske kromatografije visoke djelotvornosti (HPLC) dok se određivanje kvalitativnog i kvantitativnog udjela tvari arome provelo primjenom instrumentalne metode plinske kromatografije (GC). Vina su senzorno ocijenjena metodom 100 bodova. Dobiveni rezultati istraživanja ukazali su na značajnu različitost ispitivanih klonskih kandidata pri čemu je klonski kandidat VV-360 u obje godine istraživanja imao najveću koncentraciju nakupljenog šećera kao i koncentraciju pojedinačnih aminokiselina dok se kao klonski kandidat sa najmanjim potencijalom nakupljanja šećera ali i najvećom ukupnom kiselošću nametnuo klonski kandidat VV-479. Po aminokiselinskom profilu 9 istraživanih klonskih kandidata možemo svrstati u tri grupe i to VV-360 u kojem je dominantna aminokiselina arginin, VV-434 u kojoj dominira glutaminska kiselina te preostalih sedam u kojima se aminokiselinski profil nije značajno razlikovao. Prema koncentracijama pojedinačnih organskih kiselina u grupi klonskih kandidata sa višim sadržajem vinske kiseline možemo izdvojiti VV-483, VV-482 i VV-423 dok se višim sadržajem jabučne kiseline nametnuo klonski kandidat VV-434 koji je zajedno sa klonskim kandidatima VV-479 i VV-486 u obje godine imao i niži pH. Rezultati polifenolnog profila ispitivanih klonskih kandidata također su se značajno razlikovali pri čemu je klonski kandidat VV-479 imao najviše hidroksicimetnih kiselina, VV-438 hidroksibenzojevih kiselina, a klonski kandidat VV-360 izdvojio se većim koncentracijama ukupnih flavanola. Aromatski profil dobivenih vina razlikovao se kako između ispitivanih klonskih kandidata tako i korištenog soja kvasca. Kao najzastupljeniji monoterpen izdvojo se linalol kojega je najviše utvrđeno kod klonskog kandidata VV-438. Po vrijednostima C13-norizoprenoida izdvojio se klonski kandidat VV479 dok je najviše viših alkohola imalo vino od klonskog kandidata VV-486. Pri tome je kod svih klonskih kandidata utvrđen i značajan utjecaj ispitivanih sojeva kvasaca pri čemu je soj Anchor VIN13 utjecao na veću koncentraciju norizoprenoida i monoterpena dok je Uvaferm Affinity stvorio više estera i viših alkohola. Dobiveni rezultati utjecali su i na senzornu ocjenu analiziranih vina pri čemu su se izdvojila vina od klonskih kandidata VV482 i VV-438 oba dobivena primjenom soja kvasca Anchor VIN13.- Kraljevina is an autochthonous grapevine cultivar whose name is closely linked to the area of St. Ivana Zelina. In this area cultivar Kraljevina has a long tradition, however, was observed large variability biotypes within the population. Because of the increasing interest in the cultivation of Kraljevina as well as the lack of selected plantation pointed to the need for the implementation of clonal selection. In the process of selection of clones with basic indicators of fertility and quality of grapes is necessary to investigate the level of variability of clonal candidates in the synthesis of certain groups of chemical compounds (volatile aromatic compounds, polyphenolic compounds, amino acids, individual organic acids) which participate in the formation of the sensory properties of wine and define its quality. The aim of this study was to determine the chemical composition and content of individual organic acids, amino acids and aromatic compounds in must and wine of clonal candidates cv Kraljevina and the impact of yeast strain on the chemical composition and content of individual organic acids, amino acids and aromatic compounds in wines of Kraljevina clonal candidates. In addition, the aim was to define the sensory characteristics of wines made from clonal candidates cv Kraljevina. In the chapter Overview of previous research data about cultivar Kraljevina and its general characteristic are noted as well as previous research conected with ampelographic description and basic chemical analysis of Kraljevina must and wine. Also the importance of clonal selection and resent achivments conected with this scientifical topic are listed as well as the results dealing with positive clonal selection. Published data about aromatic compounds in must and wine as well as their concentrations, pointed out the influence of wine technology, yeast selection and cultivar as well as selected clone. Stronge difference in the amount of individual chemical compounds from the group of monoterpens and C13 norisoprenoids is defined between Chardonnay selected clones as well as in clones of Kerner, Traminer, Rhine risling. Subchapter about polyphenols is dealing with a large and diverse group of chemical compounds that can strongly influence wine quality. So, determination of possible variability between cultivars and also clonal candidat in the accumulation of this group of compounds is important, the statement that is confirmed with large amount of published scientifical research dealing with this topic. Research wines of different clonal candidates have shown that it can significantly vary in intensity and color tonality as well as in concentration of individual polyphenols. Phenolic composition, antioxidant activity and color diversity was investigated in Concord grape clones from Brazil while in the wines obtained from seven clones Monastrell significant differences in the mineral composition, organic acids and color intensity was noticed. In the chapter Material and methods the course of research and data processing is presented. The two-year study of clonal candidates cv Kraljevina (Vitis vinifera L.) was carried out in the must and wine made from grapes grown in experimental vineyards located in Sveti Ivan Zelina, specifically at the position Puščak and position Krčina. Individual bunches of selected mass positive selection within the "Clonal selection of grapevine, cv. The Kraljevina ", are propagated and planted in both locations. This study was conducted on 9 clonal candidates cv Kraljevina (VV-438, VV-406, VV-479, VV-486, VV-483, VV -423, VV-360, VV-434, VV-482) which are separated due to a sufficient number of vines from which a minimal amount of grapes needed for good mikrovinifikacijskog process of alcoholic fermentation was secured. Grape harvest of each clonal candidate was done by hand, at the time of full maturity. The grapes were harvested in plastic boxes with capacity of 20 kg. After crushing the grapes must was settled for 24 h after which the precipitate was separated and clear must was poured in the four vessels, volume of 10 L per each clone candidate (a total of 36 pots). The alcoholic fermentation was carried out using two different commercial yeast strains, Anchor VIN13 and Uvaferm Affinity. During the alcoholic fermentation degradation of sugar and temperature was regularly monitored. After completion of the alcoholic fermentation samples were taken for analysis of wine and the wine was kept in basement conditions until the time of sensory evaluation that was carried out 6 months after the completion of alcoholic fermentation. Chemical analysis of must involves determining the concentration of sugar, total acidity, the pH value and the determination of individual organic acids and amino acids. In all must samples also the value of free amino acids (FAN) and the concentration of total polyphenols was determined. In wine samples basic chemical analysis was carried on (%vol alcohol, reducing sugar, total extract, total acidity, pH, volatile acidity, ash), as well as organic acid the amino-acids and individual polyphenols and aroma compounds concentrations were done using high performance liquid chromatography (HPLC) and gas chromatography (GC). The concentration of total phenolics and free amino acids in the wine was determined by spectrophotometry. All wines were evaluated by organoleptic method of 100 points. In the chapter Results, the main results obtained in the experiment are listed. Research results indicated a significant difference of tested clonal candidates where the clone c
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. FACULTY OF FOOD TECHNOLOGY. Sub-department of Applied Chemistry and instrumental Methods. Engineering Chemistry. - Data provided ...by Europeana Collections- U ovoj disertaciji provedena je karakterizacija klorogenskih kiselina (CGAs) i analiza antioksidacijske aktivnosti u različitim vrstama kave (zelenim i prženim zrnima kave C. arabica i C. robusta, mljevenim kavama Franck Guatemala i Flatcher Olympia te instant kavama Nescafé Classic, Nescafé Espresso, Jacobs Monarch i Jacobs Intense). Prije karakterizacije CGAs, istražena su elektrokemijska svojstva kafeoilkina kiselina (CQAs), dikafeoilkina kiselina (diCQAs) i feruloilkina kiselina (FQAs) primjenom pravokutnovalne voltametrije (SWV), diferencijalne pulsne voltametrije (DPV) i protočne stripping kronopotenciometrije (FTSCP). Elektrokemijska mjerenja CGAs utvrdila su da se na površini radne elektrode odvijaju različite elektrokemijske reakcije različitim oksidacijskim mehanizmima, ovisno o kemijskoj strukturi CGAs. Karakterizacija CGAs provedena je primjenom metoda SWV, DPV, FTSCP i HPLC. Identifikacija i kvantifikacija CGAs u kavama pokazala je da najveći sadržaj ukupnih CGAs imaju zelena zrna kava. Antioksidacijska aktivnost CQAs i diCQAs istraživana je primjenom elektrokemijskog DNA biosenzora, dok je antioksidacijska aktivnost kave istraživana i primjenom DPPH i ABTS metode. Analiza antioksidacijske aktivnosti CQAs i diCQAs primjenom DNA biosenzora pokazala je ovisnost o kemijskoj strukturi ispitivanih klorogenskih kiselina. DNA biosenzor, ABTS i DPPH metode pokazale su da najveću antioksidacijsku aktivnost imaju uzorci zelenog zrna kave, zbog najvećeg sadržaja ukupnih CGAs. Istraživanjima je utvrđeno da postoji vrlo dobra do izvrsna korelacija između antioksidacijske aktivnosti kava i sadržaja ukupnih CGAs.- In this study, the characterization of chlorogenic acid (CGAs) and the analysis of antioxidant activity in different brands of coffee (green and roasted beans C. arabica and C. robusta, ground coffee Franck Guatemala and Flatcher Olympia, and instant coffee Nescafé Classic, Nescafé Espresso, Jacobs Monarch and Jacobs Intense) were investigated. Before the characterization, the electrochemical properties of the caffeoylquinic acids (CQAs), dicaffeoylquinic acids (diCQAs) and feruloylquinic acids (FQAs) were analysed by the square-wave voltammetry (SWV), differential pulse voltammetry (DPV) and flow through stripping chronopotentiometry (FTSCP). The electrochemical measurements of the CGAs have shown that on the surface of the working electrode, the different electrochemical reactions via different mechanisms of oxidation proceeded, in connection with the chemical structure of CGAs. Characterization of CGAs was performed by SWV, DPV, FTSCP and HPLC methods. The identification and quantification of the CGAs in different brands of coffee were performed by the SWV, DPV, FTSCP and HPLC methods. The results have shown that the highest CGAs total content exists in the green coffee beans. The antioxidant activity CQAs and diCQAs were analysed by DNA-biosensor while the antioxidant activity of coffee was analysed also by DPPH and ABTS methods. Antioxidant analysis of CQAs and diCQAs using DNA-biosensors has shown the dependence on the chemical structure of investigated CGAs. The methods of DNA-biosensor, ABTS and DPPH have shown the highest antioxidant activity in the green coffee beans due to the highest content of the total CGAs. Very good to the excellent correlation between the antioxidant activity of coffee and the CGAs total content was observed in this study.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. FACULTY OF FOOD TECHNOLOGY. Department of Food Technologies. Sub-department of Fruits and Vegetables Technology. - Data provided ...by Europeana Collections- Cilj rada je bio ispitati utjecaj šećera (glukoze, fruktoze, saharoze i trehaloze) na očuvanje polifenolnih
spojeva i antioksidativnu aktivnost kaša od jabuka pripremljenih zamrzavanjem i dehidratacijom
(liofilizacijom). Istraživanje je obuhvatilo ispitivanje dviju sorti jabuka (Granny Smith i Gold Rush) kroz
dvije proizvodne sezone, a također je obuhvatilo i mogućnost iskorištavanja nusprodukta industrije
voća, koru jabuke, koja se često tretira kao otpad pri preradi, a kojom bi se (kao dodatak) obogaćivala
kaša od jabuka.
Rezultati su pokazali da dodatak šećera i praha kore jabuka znakovito utječe na očuvanje odnosno
povećanje polifenolnih spojeva i antioksidacijske aktivnosti procesiranih kaša jabuka u odnosu na
kaše jabuka bez dodataka. Od ispitivanih šećera trehaloza je najviše utjecala na očuvanje promatranih
parametara dok je glukoza imala najmanji utjecaj.
Nakon skladištenja uzorci s dodatkom šećera i praha kore jabuka su i dalje imali veći sadržaj polifenola i antioksidacijsku aktivnosti u usporedbi s kontrolnim uzorcima.- The aim of this research was to determine the influence of sugars (glucose, fructose, sucrose and trehalose) on retention of polyphenols and antioxidative activity of processed (frozen and freeze-dried) apple puree. The research included examination of two apple varieties (Granny Smith and the Gold Rush) through two production seasons, and also include the possibility of exploiting by-product from fruit industry, apple peels, which are often treated as waste for enrichment of apple puree.
Results showed that the addition of sugars and apple peel powder resulted in retention of polyphenols and antioxidative activity in comparison to samples without addition of additives. The addition of trehalose had the highest impact on polyphenol and antioxidant activity retention and glucose the lowest.
After storage samples with sugar and apple peel powder addition had higher content of polyphenols and antioxidative activity in comparison to control samples.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. FACULTY OF FOOD TECHNOLOGY. Department of Food Technologies. Sub-department of Carbohydrates Technology. - Data provided by ...Europeana Collections- U ovome radu je ispitivan utjecaj sastojaka (mlijeka u prahu, zamjenske masti, paste od lješnjaka, emulgatora: lecitina, poliglicerol poliricinoleata i estera limunske kiseline i mono i diglicerida masnih kiselina, pojedinačno i u smjesama) i vremena končiranja na reološka svojstva čokoladnih masa te utjecaj mlijeka u prahu, zamjenske masti i paste od lješnjaka te
uvjeta čuvanja (temperature i vlažnosti zraka) na pojavu sivljenja površine čokolade.
Reološka svojstva mjerena su Brookfield-ovim rotacijskim viskozimetrom. Za praćenje sivljenja površine uzoraka korišten je tristimulusni kromametar, a pomoću diferencijalne motridbene kalorimetrije (DMK) praćena je promjena sastava površinskog sloja čokolade u cilju utvrđivanja mehanizma migracije masti na površinu.
Rezultati istraživanja pokazali su da vrste i svojstva sirovina imaju značajan utjecaj kako na reološka svojstva čokoladnih masa tako i na stabilnost čokolada prema sivljenju. Tip mlijeka u prahu je značajno utjecao na reološka svojstva čokoladnih masa, pri čemu su mase s mlijekom sušenim na valjcima imale niže vrijednosti reoloških parametara. Utjecaj emulgatora na reološka
svojstva čokoladnih masa u značajnoj mjeri je ovisio o svojstvima ostalih sirovina, prije svega mlijeka u prahu. Ester limunske kiseline i mono i diglicerida masnih kiselina pokazao se kao učinkovito sredstvo za podešavanje granice tečenja i plastične viskoznosti čokoladnih masa, kako pojedinačno tako i u kombinaciji s ostalim emulgatorima, prije svega s poliglicerol
poliricinoleatom. Utvrđeno je da se u slučaju priprave čokoladnih masa s mlijekom u prahu dobivenim na valjcima i uz lecitin kao emulgator vrijeme priprave mase može skratiti, a da se dobiju proizvodi željenih reoloških svojstva. Kombiniranjem emulgatora, ovisno o sastavu čokoladnih masa, postignuti su pozitivni učinci na reološka svojstva čokoladnih masa koji se ne
mogu postići primjenom pojedinačnih emulgatora.
Udio i vrsta pojedinih sastojaka, kao i vlažnost zraka tijekom skladištenja, imali su značajan utjecaj na pojavu sivljenja površine čokolada. Čokolade koje su sadržavale mlijeko u prahu sušeno na valjcima bile su otpornije na sivljenje zbog činjenice da mlijeko sušeno na valjcima sadrži veći udio slobodne mliječne masti koja je inhibitor sivljenja. Čokolade koje su sadržavale masti s nižim talištem (pasta od lješnjaka) bile su sklonije sivljenju, već pri nižoj vlažnosti zraka. Uzorci koji su sadržavali kakao maslac ekvivalent (zamjenska mast) više su posivjeli u odnosu na one s istim udjelom ukupne masti koja je iz kakaovog maslaca i mliječnih komponenti. DMK mjerenjima posivljenog površinskog sloja čokolade dobile su se krivulje koje
su poslužile za izračunavanje entalpije taljenja (ΔH). Tijekom skladištenja čokolade, posebno pri povišenoj relativnoj vlažnosti (75 %), došlo je do sniženja entalpije taljenja saharoze, a povećanja entalpije taljenja kakaovog maslaca, te se može zaključiti da je povećana vlažnost zraka utjecala na otapanje šećera u površinskim slojevima čokolade što je omogućilo izlazak
masti na površinu.- Influence of ingredients (milk powder, vegetable fat, hazelnut paste, emulsifiers: lecithin,
polyglycerol polyricinoleate, mono-diglyceride ester of citric acid, individually and in
combinations) and conching time on rheological properties of chocolate masses, as well as
influence of milk powder, vegetable fat and hazelnut paste on fat bloom of chocolate were
investigated in this research.
Rheological properties were investigated using Brookfield rotational viscometer. Fat
bloom of chocolates was monitored using tristimulus chromameter and, in order to reveal
mechanism of fat migration, change in composition of chocolate surface was determined by
differential scanning calorimeter.
Results showed that types and properties of ingredients significantly influenced both
rheological properties and stability of chocolates towards fat bloom. Milk powder type had
significant influence on rheological properties of chocolate masses, whereat masses with roller
dried milk powder had lower values of rheological parameters. Influence of emulsifiers on
rheological properties highly depended on properties of other ingredients, mainly milk powder.
Mono-diglyceride ester of citric acid proved to be efficient regulator of rheological properties of
chocolate masses, individually and in combinations, primarily with polyglycerolpolyricinoleat.
When chocolate masses where produced with roller dried milk powder and emulsifier lecithin,
time of chocolate mass preparation could be reduced without unwanted rheological effects.
Combinations of emulsifiers positively influenced rheological properties of chocolate masses, in
the way which couldn’t be achieved with individual emulsifiers.
Content and type of ingredients, as well as relative humidity during storage significantly
influenced fat bloom of chocolate. Chocolates containing roller dried milk powder were more
resistant to fat bloom due to higher content of free milk fat, which is fat bloom inhibitor.
Chocolates containing low melting fats (hazelnut paste) were more prone to fat bloom, even at
lower humidity. Samples containing cocoa butter equivalents (vegetable fat) were more bloomed
than samples containing same amount of fats from cocoa butter and milk powder. DSC curves,
which were used for melting enthalpy (ΔH) calculations, were obtained from DSC analyses of
grey layers from chocolate surfaces. During chocolate storage, especially at higher relative
humidity (75 %) sucrose melting enthalpy declined, while cocoa butter enthalpy increased. This
indicates that increased relative humidity caused sugar melting in surface layers of chocolate,
which enabled migration of fat to the surface.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. FACULTY OF FOOD TECHNOLOGY. Department of Applied Chemistry and Ecology. - Data provided by Europeana Collections- U ovome radu ...ispitivano je voltametrijsko ponašanje galne kiseline (GK) i glavnih katehinskih spojeva ili katehina epigalokatehin galat (EGCG), epigalokatehin (EGC), epikatehin (EC) i epikatehin galat (ECG) prisutnih u zelenim i crnim čajevima. Također, razvijena je nova elektroanalitička metoda za karakterizaciju katehina u vodenim ekstraktima odnosno suhom lišću zelenih i crnih čajeva.
Podaci o katehinskom profilu zelenih i crnih čajeva dobiveni su primjenom tekućinske kromatografije visoke djelotvornosti u kombinaciji s elektrokemijskim detektorom (HPLCECD).
Ustanovljeno je da su glavni katehini u zelenim i crnim čajevima EGCG i EGC, koji čine 84-89 % ukupnih katehina zelenog i 53-89 % ukupnih katehina crnog čaja.
Voltametrijska mjerenja pravokutnovalna voltametrija (SWV) i ciklička voltametrija (CV) na elektrodi od staklastog ugljika (GCE) pokazala su da je elektrokemijska oksidacija katehina difuzijom kontrolirani kvazireverzibilni proces. Voltametrijska svojstva katehina funkcija su koncentracije katehina, pH i brzine polarizacije. Utvrđeni su optimalni uvjeti i validirana je SWV kao metoda za karakterizaciju katehina u zelenim i crnim čajevima.
Analizirani su uzorci zelenih i crnih čajeva primjenom SWV metode na GCE i određen je sadržaj katehina u vodenim ekstraktima čajeva. Koncentracije katehina dobivene SWV metodom gotovo su identične onima dobivenima HPLC-ECD analizom. Stoga, SWV metoda predstavlja vrlo dobru alternativnu metodu analize katehinskih spojeva u ekstraktima zelenih i crnih čajeva u odnosu na zahtjevnu i skupu HPLC analizu.
Kao dodatna metoda karakterizacije katehina korištena je abrazivna SWV s anodnim otapanjem uzorka imobiliziranog na površini parafinom impregnirane grafitne elektrode (PIGE). Ova metoda pokazala se kao brza i jednostavna semikvantitativna metoda za detekciju elektroaktivnih katehina u suhom lišću zelenih i crnih čajeva.- The voltammetric behaviour of gallic acid (GA) and the main catechins epigallocatechin
gallate (EGCG), epigallocatechin (EGC), spicatechin (EC), and epicatechin gallate (ECG) found
in green and black teas was investigated. In addition, novel electroanalytical procedure for
characterization of catechins in tea extracts and dry tea leaves was developed.
The concentrations of individual catechins in green and black teas were determined using
high-performance liquid chromatography with electrochemical detection (HPLC-ECD). EGCG
and EGC were the major catechins in green and black tea samples, representing 84-89% and 53-
89% of total catechins, respectively.
Square-wave and cyclic voltammetry experiments showed that the oxidation of catechins
on glassy carbon electrode (GCE) is a quasireversible and diffusion controlled process. It has
been shown that voltammetric properties of catechins depend on pH, scan rate and catechin
concentration. A new SWV method for characterization of catechins has been established,
optimized and validated. The proposed method was applied to characterize the catechins in green
and black teas.
Water extracts of green and black teas were analysed using SWV on GCE. Amounts of
catechins in green and black teas obtained using SWV were in good agreement to those obtained
using HPLC-ECD. Accordingly, SWV has been shown to be a good alternative compared to
more expensive, laborious and time-consuming HPLC methods.
In addition, the abrasive stripping SWV of microparticles of tea leaves immobilized on
the surface of paraffin-immpregnated graphite electrode (PIGE) was used for characterization of
catechins as well. This semiquantitative method enabled a fast and simple screening of catechins
in dry leaves of green and black teas.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. FACULTY OF FOOD TECHNOLOGY. - Data provided by Europeana Collections- Okarakterizirane su sortne rakije komovice proizvedene ...tradicionalnim načinom destilacije komine najznačajnijih sorti grožda u Istri, i to na osnovi sastava hlapivih spojeva arome. U proizvedenim rakijama komovicama te u različitim frakcijama destilata, kombiniranom tehnikom plinske kromatografije i spektrometrije masa (GC/MS), identificirani su najvažniji spojevi primarne i sekundarne arome (terpeni, C13-norizoprenoidi, viši alkoholi, masne kiseline, esteri, aldehidi, ketoni, te acetali), dok su njihovi udjeli određeni tehnikom plinske kromatografije uz plamenoionizacijski detektor (GC/FID). Uporabom statističkih metoda analize
utvrđene su razlike u sastavu hlapivih spojeva arome između rakija komovica od različitih sorti.
Provedeno je i senzorsko ocjenjivanje rakija DLG metodom, te su utvrđene korelacije između udjela spojeva arome i senzorske kvalitete. Zaključeno je da osnovu arome svih sortnih rakija komovica uključenih u istraživanje čine najvažniji spojevi sekundarne arome: viši alkoholi, hlapive masne kiseline, hlapivi esteri, te acetaldehid, a u pojedinim slučajevima i 1-heksanol.
Viši udjeli većine spojeva sekundarne arome pronađeni su u rakijama od sorti crnog grožda Teran i Cabernet Sauvignon, ali je utvrđeno da njihovi udjeli prvenstveno ovise o kvaliteti grožda i načinu pripreme komine. Rakije komovice od sorti Muškat bijeli i Muškat ruža porečki karakterizirala je izražena primarna, muškatna aroma, kao posljedica pojave visokih udjela
monoterpena. Rakije komovice od sorte Malvazija istarska karakterizirali su izrazito visoki udjeli metanola. Utvrđeno je da povišeni udjeli masnih kiselina srednjeg lanca, a posebno njihovih etilnih estera te ostalih estera, mogu poslužiti kao pokazatelji bolje senzorske kvalitete, dok povišeni udjeli seskviterpena, diterpena, C6-alkohola, metanola, octene kiseline, masnih
kiselina kratkog i dugog lanca te njihovih etilnih estera, acetatnih estera i aldehida, mogu poslužiti kao pokazatelji slabije senzorske kvalitete rakije komovice.- Monovarietal grape marc distillates, produced by traditional distillation of marcs from the
most important grape varieties in Istria, were characterized on the basis of volatile aroma
compound composition. In produced distillates, as well as in different fractions of the distillates,
the most important primary and secondary aroma compounds (terpenes, C13-norisoprenoids,
methanol, higher alcohols, fatty acids, esters, aldehydes, ketones and acetals) were identified by
gas chromatography-mass spectrometry (GC/MS), while their amounts were determined by gas
chromatography with flame-ionization detector (GC/FID). The differences in volatile aroma
compound composition between distillates made from different grape varieties were determined
using statistical methods. The distillates were subjected to sensory evaluation by the DLG
method, and correlations were determined between the amounts of aroma compounds and
sensory quality. It was concluded that basic aroma of all investigated monovarietal grape marc
distillates consists of the major secondary aroma compounds such as higher alcohols, volatile
fatty acids, volatile esters and acetaldehyde, and in some cases, 1-hexanol. Distillates made from
red grape varieties Teran and Cabernet Sauvignon contained higher amounts of the majority of
secondary aroma compounds, but it was assumed that their amounts mostly depend on the
quality of grapes and production parameters. Marc distillates made from Muscat blanc and
Muscat rose of Porec grape varieties were characterized by pronounced primary muscat aroma,
due to high amounts of monoterpenes. Malvazija istarska grape marc distillates were
characterized by very high methanol content. It was determined that increased amounts of
middle-chain fatty acids, and especially their ethyl esters, as well as other esters, could be used
as indicators of higher sensory quality, while increased amounts of sesquiterpenes, diterpenes,
C6-alcohols, methanol, acetic acid, short and long-chain fatty acids and their ethyl esters, acetates
and aldehydes could be utilized as indicators of lower sensory quality of grape marc distillates.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
