Chemical and sensory changes in fresh cider spirits during maturation in inert containers.

BACKGROUND: Fresh cider spirits are alcoholic beverages mainly constituted by volatile compounds from apples that are formed during fermentation or generated during distillation. In this study the chemical and sensory changes that take place during the maturation of fresh cider spirits in inert containers made of stainless steel and glass were investigated. RESULTS: The type of container did not influence the maturation process for any of the studied compounds. Esterification, acetalisation and hydrolysis reactions occurred during the maturation of cider distillates over 24 months, giving rise to several changes in the original composition of this alcoholic beverage, but neither oxidation nor evaporation reactions were detected. A decrease in ethyl acetate, ethyl lactate, diethyl succinate and acetal was observed and an increase in fatty acid ethyl esters and 1,1,3-triethoxypropane. Likewise, the sensory evaluation of the spirits was significantly influenced by the maturation time, with matured samples obtaining higher scores than fresh ones. CONCLUSION: The presence of reactive compounds in recently distilled products makes a period of around 12 months of maturation advisable to reach equilibrium and to improve the sensory assessment of cider distillates consumed in the fresh state.

Production and composition of cider spirits distilled in "alquitara".

The capacity of alquitara (a traditional distillation system) to produce cider brandies is evaluated. To do so, the chemical composition of 12 fractions obtained during the distillation process and the cider brandies obtained from five ciders were analyzed (alcohol strength, methanol, volatile substances, furfural, and metals), taking into account European and Spanish legislation. During the course of distillation, an important increase in methanol, furfural, 2-phenylethanol, and metals in the last fractions was observed, while fusel oils were more abundant in the first fractions collected. Only acetaldehyde behaved differently, showing a minimum concentration in the middle fractions that might be explained by its formation on the surface of alquitara. On the other hand, the final distillates obtained by means of this method complied with the considered regulations. Worth highlighting in this regard are the low levels of a potential toxin such as methanol, as well as the detection of a constant ratio for methanol, ethanol, and fusel oil for the pairs of cider/spirits analyzed, which could be interpreted as an indication of good uniformity in the distillation system and method, thus guaranteeing product quality.

Determination of volatile compounds in apple pomace by stir bar sorptive extraction and gas chromatography-mass spectrometry (SBSE-GC-MS).

UNLABELLED: A method based on stir bar sorptive extraction combined with gas chromatography-mass spectrometry detection (SBSE-GC-MS) has been optimized with the aim of applying it to the analysis of apple pomace. The method allowed the identification of 124 volatile compounds after 3 h of extraction with a precision (RSDs) ranging between 2% (linalool) and 11% (ethyl hexanoate). Its use in analyzing varietal apple pomace revealed the interest of this substrate as regards its content in aromas. From a semi-quantitative point of view, the higher content in aldehydes and esters of the Blanquina variety is worth highlighting, as are the greater concentration of acids in the Clara variety and the higher content of terpenes and norisoprenoides in the Coloradona variety. In contrast, the Ernestina and Perico varieties presented the lowest levels of aromas. PRACTICAL APPLICATION: The analysis of varietal apple pomaces showed the importance of this type of waste in the food industry, both for its content in aromas such as for its use as substrate in biotechnological processes.

Yeast species associated with the spontaneous fermentation of cider.

This paper reports the influence of cider-making technology (pneumatic and traditional pressing) on the dynamics of wild yeast populations. Yeast colonies isolated from apple juice before and throughout fermentation at a cider cellar of Asturias (Spain), during two consecutive years were studied. The yeast strains were identified by restriction fragment length polymorphism analysis of the 5.8S rRNA gene and the two flanking internal transcribed sequences (ITS). The musts obtained by pneumatic pressing were dominated by non-Saccharomyces yeasts (Hanseniaspora genus and Metschnikowia pulcherrima) whereas in the apple juices obtained by traditional pressing Saccharomyces together with non-Saccharomyces, were always present. The species Saccharomyces present were S. cerevisiae and S. bayanus. Apparently S. bayanus, was the predominant species at the beginning and the middle fermentation steps of the fermentation process, reaching a percentage of isolation between 33% and 41%, whereas S. cerevisiae took over the process in the final stages of fermentation. During the 2001 harvest, with independence of cider-making technology, the species Hanseniaspora valbyensis was always isolated at the end of fermentations.