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The phenolic compounds chlorogenic acid, p-coumaric acid, protocatechuic acid, (+)-catechin, (−)-epicatechin, phloridzin and di-, tri- and tetrameric procyanidins in apple juice were separated by reversed-phase high-performance liquid chromatography on a C18 column using a methanol-dilute hydrochloric acid solvent gradient. Absorbance ratios and UV spectrometry were used to identify the separated phenolic compounds and to check their purity.

The objective of this work was to study the effect of alcoholic fermentation on the content of phenol compounds of five cider apple varieties. The initial content in the apple juice samples, as determined by HPLC, varied from 188.4 to 2776.17 m mg.L-1. In three of them (DC, PJ, GU), the total phenol compounds remained unaffected by fermentation. However, in two (DM, KE), the final values were lower (55 and 313 mg.L-1). In these apple cider, the values of caffeic acid increased from 6.6 mg.L-1 to 41.8 mg.L-1. The catechin content increased during the process, approximately 13 mg.L-1 independent of the variety. The other phenols class did not present any modifications due to the alcoholic fermentation, maintaining the phenolic compounds of original clarified apple juice in the cider.O objetivo deste trabalho foi estudar o efeito da fermentação alcoólica no teor de compostos fenólicos de cinco mostos de maçãs industriais. Os compostos fenólicos foram analisados por HPLC. Os mostos apresentaram fenóis totais entre 188,4 a 2776,17 mg.L-1. Os teores de fenóis durante a fermentação permaneceram os mesmos para as variedades DC, PJ e GU, entretanto, em DM e KE foi observada uma diminuição dos teores de fenóis (55 e 313 mg.L-1, respectivamente). Em KE o teor do ácido caféico aumentou de 6,6 mg.L-1 para 41,8 mg.L-1. O teor de catequinas aumentou cerca de 13 mg.L-1 durante o processo, independente da variedade. As outras classes de fenóis não apresentaram modificações com a fermentação alcoólica, permanecendo na sidra os compostos fenólicos do suco de maçã clarificado.

Polyphenols influence the organoleptic properties of cider. Polyphenols in cider apples are those of table apples but with higher concentrations. The three main classes are flavan-3-ols, monomeric (catechins) and oligomeric or polymeric (procyanidins), hydroxycinnamic acids and dihydrochalcones. Procyanidins generate bitterness and/or astringency, depending on their size. The colour of ciders is due to ” enzymatic browning ”, a complex chain of reactions initiated by the oxidation of cafeoylquinic acid onto its highly reactive quinone by polyphenoloxydase. Apple phenolics were followed quantitatively during cider elaboration for five varieties during three years and at two maturation steps. Their impact on the taste and mouthfeel of the final cider were assessed. Three points were studied in depth : retention of tannins on apple pomace; evolution of the quinones generated by action of polyphenoloxydase on cafeoylquinic acid ; competition for dioxygen between yeasts and polyphenoloxydase. Major differences occurred between fruit and must. Fermentation by Saccharomyces uvarum had very little impact on the polyphenolic composition. Organoleptic assessment of the final ciders confirmed the link between polyphenols and bitterness and/or astringency; the jury detected differences due to post-harvest maturation and pomace oxigenation prior to pressing. Isolated procyanidins bound spontaneously to apple cell walls by H-bonds and hydrophobic interactions. The amount of bound procyanidins increased with their size and concentration, and could be influenced by temperature, presence of salts or ethanol, and by the physical state of the cell walls. These interactions explain the selective retention of high molecular weight procyanidins during apple pressing. Oxidation products were systematically searched in apple musts by LCMS. Numerous products were present, and we identified addition products involving molecules of the same class, sometimes with addition of water, and co-dimers i.e. from reaction between different classes. Four dimers of cafeoylquinic acid were isolated from synthetic solutions and their structures were elucidated by LC-MSn and NMR. Polyphenoloxydase activity and polyphenol concentrations in cider apple juices are such that all dissolved oxygen is rapidly consumed. Anaerobic conditions are thus established at the start of fermentation, and will influence yeast growthand indirectly the stability of the final product. The phenolic composition of cider is for the most part established at pressing, and we have identified a key role of oxygen in cider fermentations. More work is needed notably to further clarify the diversity of oxidation products, their reaction schemes and organoleptic properties. IUFoST 2006 DOI: 10.1051/IUFoST:20060374

Cell walls were prepared from apple parenchyma by a phenol:buffer procedure. Polyphenols were extracted from freeze-dried apple parenchyma by methanol and water:acetone, and purified by preparative HPLC. Interactions were quantified by bringing into contact suspended cell walls and polyphenol solutions. Hydroxycinnamic acids and (-)-epicatechin did not bind to cell walls. Binding of procyanidins was fast and reached up to 0.6 g per g cell walls. The amounts of procyanidins bound increased with the initial concentration and with DPn. Procyanidins could be partially desorbed by buffer, more being desorbed in the presence of dissolved cell wall polysaccharides. They were totally desorbed using 8 M urea or acetone:water. Higher polymers were bound selectively from procyanidin mixtures, and very high average DPn were obtained in extensively washed complexes. Binding of procyanidins inhibited enzymic degradation of the cell walls.

Les derives des acides hydroxycinnamiques (AHC) sont naturellement presents dans les jus de fruits, vins et cidres. Au cours de ce travail nous avons determine, a l'aide de plans d'experience, les effets de ces composes sur la croissance d'une souche de Oenococcus oeni et d'une souche de Lactobacillus plantarum. Les plans d'experience comprennent trois facteurs : pH, taux d'inoculation et concentration en composes phenoliques. Ces composes sont : l'acide quinique, les AHC libres (acides ferulique, p-coumarique et cafeique), les formes esterifiees (acides 5'-cafeoyl-quinique et p-coumaroyl-quinique) ainsi que deux melanges equimolaires (acide cafeique / acide quinique et acide p-coumarique / acide quinique). Les resultats ont montre que les AHC libres sont inhibiteurs vis-a-vis des bacteries lactiques, alors que leurs esters n'ont que peu ou pas d'effet. Les AHC libres peuvent etre classes par ordre d'actions inhibitrices decroissantes : acide ferulique, acide p-coumarique et acide cafeique, c'est-a-dire dans l'ordre decroissant de leur hydrophobicite. Les deux bacteries examinees reagissent differemment vis-a-vis de la toxicite des AHC : pour Oenococcus oeni, on observe a la fois une baisse du μ apparent et de la quantite de la biomasse produite. En revanche, pour Lactobacillus plantarum, l'effet des AHC concerne surtout la reduction du μ apparent.

The cortex of 14 French apple varieties (12 cider and 2 juice varieties), one English cider variety, and one dessert apple (i.e., Golden Delicious) were studied for their polyphenol composition. Total polyphenols were assayed by the Folin-Ciocalteu method, and the precise polyphenolic composition (monomeric catechins, proanthocyanidins, hydroxycinnamic acids, and dihydrochalcones) was obtained by HPLC following thiolysis. ESI-MS and ESI-MS/MS analyses showed that chlorogenic acid and p-coumaroylquinic acid were methylated under the conditions of thiolysis. Depending on the variety, the global polyphenol concentration varied from 1 to 7 g per kilogram of fresh cortex. Cider varieties globally showed a higher polyphenol concentration than the dessert apple Golden Delicious, bitter varieties being the more concentrated. The proportion of the polyphenol classes varied greatly from one cultivar to another. For all varieties, procyanidins were always the predominant class. They were mainly constituted of (-)-epicatechin units with a small proportion of (+)-catechin as a terminal unit. The average degree of polymerization ranged between 4.2 and 7.5 depending upon the variety with an exception for the sharp varieties Guillevic and Avrolles which showed significant concentrations of procyanidins with DPn of 40 and 50, respectively.

L'examen mycologique de neuf lots de pommes destinees a la transformation revele une predominance d'alterations fongiques liees aux blessures que subissent ces fruits a la cueillette ou au cours des manutentions et du stockage. Parmi les champignons detectes, les roles possibles du Penicillium expansum (producteur de patuline) et des Fusarium (elaborant des trichothecenes) dans l'etiologie du cancer de l'oesophage sont discutes.

There is strong epidemiological evidence that oesophageal cancer in the West of France is related to alcohol consumption. Various laboratory studies have been undertaken in connection with this finding. Samples of the spectrum of alcoholic drinks consumed in the region, notably apple cider and its distillates, were collected from retail outlets and from farms: several distillates produced under experimental conditions in the laboratory were also examined. These samples were analysed for the presence of selected nitrosamines; small amounts were found for the most part in beer, which is little consumed in Normandy and Brittany. Mutageniticy tests on the apple cider based drinks and on other commercially available alcoholic beverages (beer excepted), have shown a weak response, for the most part in farm distillates, that can be attributed neither to nitrosamines nor to polycyclic aromatic hydrocarbons, but to some other as yet unidentified compounds.

Among the lactic microflora of ciders it was found that the species Leuconostoc oenos was predominant at the end of the alcoholic fermentation as well as at the end of the malo-lactic conversion. Among yeasts, the genera Saccharomyces was predominant at the end of fermentation. However, in the case of one juice characterised by a low initial level of bacteria, a high amount of phenolic compounds and a small quantity of total nitrogen, the whole lactic flora was no longer detected after a fortnight.

J. Inst. Brew. 114(2), 102–110, 2008 This study looked at the effects of an operation used by some French cider makers in order to optimise the process. The tech-nique examined is one that consists of reducing the yeast population during fermentation, so that the fermentation velocity decreases. At different stages of the fermentation, several deci-mal biomass reductions were performed and their effects were determined both by counting the two main yeast populations (fermenting yeast and oxidative yeasts) and by analysing the main parameters involved in yeast growth and fermentation (total nitrogen, density). In the present experiments, it was shown that a single decimal biomass reduction was enough to control the fermentation once the density of the untreated raw juice had undergone a 5 to 10 point drop corresponding to the consumption of about 13–26 g sugar per litre. This drop was linked to the growth phase of the yeasts in the untreated assay. When this reduction was performed later, the fermentation velocity became too low to reach the expected density. Nitrogen consumption appears to be one of the key parameters of this operation.

Direct thiolysis of crude plant materials and HPLC analysis of the reaction media were used to quantify and to characterise procyanidins (condensed tanins) and other main polyphenols of three dessert apple varieties. Results showed evidence of the large predominance of the procyanidin class in the polyphenolic composition of dessert apple skin and flesh. The structure of procyanidins was wholly homogeneous with (-)-epicatechin representing more than 95% of the constitutive flavan-3-ol units and with average degrees of polymerisation in the 5–7 range.