Volatile compounds in juices and ciders made from Finnish apple cultivars

Abstract

Apples (Malus domestica Borkh.) are globally significant, ranking second in consumption and third in production. While primarily consumed fresh, a substantial portion is processed into value-added products like apple juice and cider. Cider, defined as a fermented alcoholic beverage, has gained popularity for its refreshing attributes and gluten-free nature. This study investigates how Finnish apple cultivars and the choice of Saccharomyces cerevisiae and Torulaspora delbrueckii yeast strains influence the volatile organic compounds of apple beverages. The juice and cider samples utilized in this investigation were derived from a prior study conducted last year and have been stored at -22 °C since then. The apple cultivars, managed by the Natural Resources Institute Finland (Luke), were harvested in autumn 2022. Juice samples from six native apple cultivars, including Antonovka, Mustialan Iso Venäläinen, Aleksanteri, Rambo, along with two unidentified cultivars, were analysed in triplicate, resulting in 18 juice samples. These juice samples were then separately inoculated with S. cerevisiae and T. delbrueckii in triplicate to produce cider samples. In the current study, the ciders were also analysed in triplicate, resulting in a total of 108 cider samples. All samples were investigated using headspace solid-phase microextraction gas chromatography-mass spectrometry. Juice samples presented 36 volatile compounds, whereas cider samples revealed 49. While certain volatile compounds were common to both juice and cider samples, cider samples boasted a more extensive range of these compounds compared to juice. Moreover, ciders featured distinctive volatile groups, like acetals and lactones, absent in juice samples. Through principal component analysis, correlations were identified between S. cerevisiae and esters as well as volatile acids, while T. delbrueckii exhibited correlations with higher alcohols and volatile acids. In addition to yeast strains, the choice of apple cultivar played a vital role in the formation of volatile compounds. Certain cultivars, such as Mustialan Iso Venäläinen, Rambo, and Antonovka, exhibited significant correlations with specific volatile compound profiles. This study unveils insights into crafting premium apple-based beverages from specific cultivars and catalysing the commercialization of native Finnish apple varieties.