No abstract

The amino acid profile in dessert apple must and its effect on the synthesis of fusel alcohols and esters in cider were established by instrumental analysis. The amino acid profile was performed in nine apple musts. Two apple musts with high (>150 mg/L) and low (<75 mg/L) nitrogen content, and four enological yeast strains, were used in cider fermentation. The aspartic acid, asparagine and glutamic acid amino acids were the majority in all the apple juices, representing 57.10% to 81.95%. These three amino acids provided a high consumption (>90%) during fermentation in all the ciders. Principal component analysis (PCA) explained 81.42% of data variability and the separation of three groups for the analyzed samples was verified. The ciders manufactured with low nitrogen content showed sluggish fermentation and around 50% less content of volatile compounds (independent of the yeast strain used), which were mainly 3-methyl-1-butanol (isoamyl alcohol) and esters. However, in the presence of amino acids (asparagine, aspartic acid, glutamic acid and alanine) there was a greater differentiation between the yeasts in the production of fusel alcohols and ethyl esters. High contents of these aminoacids in dessert apple musts are essential for the production of fusel alcohols and most of esters by aromatic yeasts during cider fermentation.

The aim of this study was to identify the main amino acids responsible for the production of esters in ciders. The experiments were carried out in apple must and synthetic must. The amino acids were analysed by high‐performance liquid chromatography and the volatile compounds by gas chromatography. Aspartate, asparagine and glutamate positively influenced the production of esters in the cider models and were used in the experiments with mixtures. The response surface generated by the proposed model yielded two regions that maximized the production of esters. In addition, the combination of aspartate and glutamate predicted a higher production. The optimal suggested concentrations were 43.4% of aspartate and 56.6% of glutamate for 120 mg/L of total nitrogen. The apple must supplemented with these two amino acids resulted in four times more esters than in the same cider without supplementation, demonstrating the effectiveness of the proposed model.

This study aims to evaluate the aromatic profile of fermented apple, obtained by the action of strains of Hanseniaspora uvarum and Hanseniaspora guilliermondii using two methods of analysis: static headspace and solid phase microextraction (SPME). The results obtained confirm that the strains of the Hanseniaspora genus contributed positively to the aroma profile of fermented apple, producing considerable amounts of esters and higher alcohols. In comparing the methods of analysis of aromatic compounds using headspace and SPME, it was verified that by using the headspace method it was possible to capture amounts that were up to 16 times greater than the value of the volatile compounds obtained by SPME. However, when using SPME, 5 times more compounds were obtained than when using headspace. Even so, in the conditions of this study it was noted that headspace was more efficient in the extraction of the aromatics of fermented apple when taking into consideration the cost effectiveness of both methods.

This study evaluated the effect of the operations of selection, cleaning and sanitizing with sodium hypochlorite, on the populations of yeasts and lactic acid bacteria present in apple cider must, elaborated from commercial and industrial fruit. The microbial load differed between the cultivars and classes of fruit. The total populations of yeasts and lactic acid bacteria were higher in the industrial fruit. The operation of selection avoided cross-contamination and the presence of organic compounds that might react with the chlorine. Washing the apples decreased the populations of these microorganisms by one logarithmic cycle. Hierarchical cluster analysis indicated that sanitization was effective at a concentration of 100 mg/L for 5 min. The sanitizer was not effective in totally eliminating the microorganisms in populations greater than 10 4 CFU/mL. Selection and washing help reduce natural microbiota, making sanitization more effective, and positively affecting food safety and the quality of unpasteurized cider. PRACTICAL APPLICATIONSThis article presents the results, and a thorough discussion, of the use of prefermentation operations that can be used to reduce the microbial load of apple must, which is to be turned into cider. Among all the various techniques and controls, the three that were most noteworthy were analyzed (selection of fruits, washing and sanitizing with chlorine, followed by rinsing). These operations are critical control points, and if they are planned and monitored then can reduce or eliminate microorganisms (pathogens or not), eliminate or reduce the need for sulfite, facilitate the cleaning and disinfection of the environment and equipment, increase food safety, and ensure the production of high-quality unpasteurized cider.