Juan J. Mangas

Biochemical study of the ripening of cider apple varieties

ZusammenfassungDie Änderung der Zusammensetzung der wichtigsten Zucker und organischen Säuren in fünf asturianischen Apfelsorten wurden während der Endphase des Reifens durch Hochleistungsflüssigchromatographie untersucht. Ebenfalls wurden im gleichen Zeitraum die Veränderungen im Stickstoff-, Polyphenol-, Zucker- und Stärkegehalt dieser Sorten bestimmt. Unterschiede ergaben sich bei den wichtigsten Zuckerarten (Fructose, Saccharose und Glucose) und Sorbitol der fünf Apfelsorten. Die größte Fructosemenge wurde in der Endphase des Reifens angereichert. Mit fortschreitendem Reifen nahm der Gesamtzuckergehalt zu, wohingegen der Gehalt an Apfelsäure, Stärke, Stickstoff und Polyphenolen abnahm.SummaryChanges in the major sugars and organic acids in five Asturian apple varieties during the final stage of ripening were studied using HPLC. The changes in total nitrogen, polyphenols, sugars and starch in these varieties were also studied over the same period. Differences were noted among the major sugars (fructose, sucrose und glucose) and sorbitol for the five varieties studied. Fructose accumulated in a greater quantity in fruit during the final stage of ripening. The overall sugar content increased, while the malic acid and starch contents decreased in the final stage, which was preceded by a minimum in the nitrogen and polyphenol contents.

Changes in phenolic composition of apple juices by HPLC with direct injection

An analytical procedure for the quantitative determination of the major polyphenols in apple juices which successfully employs a RP-HPLC system without prior treatment of the sample is described. Apple juices were clarified by microfiltration and ultrafiltration without previous treatment. Polyphenols monitored were influenced by clarification technology employed for stabilising the apple juices. The p-coumaric acid derivative was significantly affected by membrane type and filtration time, while (−)-epicatechin and phloridzin were influenced by filtration time.

Influence of cider-making technology on low-boiling-point volatile compounds

ZusammenfassungDie hauptsächlichen niedrigsiedenden Aromakomponenten aus zwölf Apfelweinen, die mit verschiedenen technischen Methoden (verschiedene Preßgeschwindigkeiten und Klärungssysteme) erhalten wurden, wurden durch Gaschromatographie analysiert. Die chromatographischen Daten zeigten, daß der Anteil an Ethylacetat, Methanol, Propanol,Isobutanol, 2-Me-thylbutanol und 3-Methylbutanol von der Preßgeschwindigkeit abhängt, ebenso wie der Anteil an Methanol,Isobutanol, 2-Methylbutanol und 3-Methylbutanol vom Klärungssystem. Ein Einfluß beider Faktoren wurde nur fürIsobutanol und 3-Methylbutanol beaobachtet, während der Butanolanteil von der angewandten Technologie unabhängig ist.AbstractMajor low-boiling-point aroma components present in twelve ciders obtained by different technological methods involving different pressing speeds and clarification systems were evaluated by gas chromatography. Variance analysis of chromatographic data show that ethyl acetate, methanol, propanol, isobutanol, 2-methyl butanol and 3-methyl butanol contents depend on the pressing speed. In the same way, the metanol, isobutanol, 2-methylbutanol and 3-methylbutanol contents depend on the clarification system employed. The interactive effect of both factors was observed only forIsobutanol and 3-methylbutanol whereas the butanol content was independent of the technology used.

Characterisation of fermented apple products using data obtained from GC analysis

A study was conducted to typify ciders on the basis of their aromatic profile. Controlled cider fermentations were carried out using a mixture of Kloeckera apiculata, Saccharomyces cerevisiae and Leuconostoc oenos as inocula. Ciders were obtained under different technological conditions, taking into account several factors, such as the presence or omission of Kl. apiculata, the addition of yeast cell walls, temperature and the timing of inoculation with lactic acid bacteria. Fermentation at a low temperature, and the presence of Kl. apiculata increased the concentration of ethyl acetate. The production of propan-1-ol and 2-methylbutan-1-ol was found to be stimulated by the addition of yeast cell walls, and an increase in the fermentation temperature promoted a higher degree of synthesis of isoamyl alcohol and isobutanol. The use of principal component analysis (PCA) and linear discriminant analysis (LDA), allowed the authors to typify fermented apple products on the basis of the fermentation temperature and the presence of apiculate yeast.

Automated determination of total polyphenols in apple juice.

ZusammenfassungEs wurde eine automatische Methode zur Erfassung der gesamten Polyphenole in Apfelsaft mittels Folin-Ciocalteu-Reagens angewandt. Chlorogensäure wurde als Standard gewählt, da mit ihr ein ähnliches kinetisches Verhalten in der Standardprobe beobachtet wurde. Es wird eine unkomplizierte Methode mit guter Reproduzierbarkeit (Probenfrequenz C.V. <1%), Probenfrequenz (48 pro h) und gutem Verhältnis zur traditionellen schrittweisen Methode vorgeschlagen.AbstractAn automated method of total polyphenols analysis in apple juice using the Folin-Ciocalteu reagent is presented. Chlorogenic acid was selected as the standard since a similar kinetic behaviour, standard-sample, was observed. A straightforward method with good reproducibility (CV <1%), sampling frequency (48 h-1) and correlation with the traditional batch method (r=0.9924) is proposed.