Bioprocessing of Alcoholic Beverages from Apples and Pears: Effects of Raw Materials and Processes on Quality
Year: 2022
Type: dissertation
Abstract: Alcoholic beverages made from non-grape fruits by fermentation, such as apple cider and pear perry, are increasingly popular nowadays, as well as being among the most commonly consumed products in recent years. In general, industrial producers use specific ‘cider apple’ or ‘perry pear’ cultivars mixed with dessert fruit cultivars to obtain alcoholic fruit beverages (AFBs) with a high quality. A stable and low-price supply of local specialty fruit cultivars has been established in countries with a long history of cider making, such as England and France, whereas their availability is limited in the Nordic countries, like Finland. In addition, there are no existing breeding programs in Finland for ‘specialty beverage’ cultivars of apples or pears. Thus, the selection of traditional local cultivars or the development of novel cultivars for AFB production is of high economic importance in the industry. At the same time, alcoholic fermentation is a complex, yeast-driven process. Utilization of non-Saccharomyces yeasts in AFBs fermentation to create more versatile flavor profiles can also be considered to be a recent and growing trend in the beverage industry. The aim of this doctoral research was to investigate the utilization of apple and pear cultivars, as well as Saccharomyces and non-Saccharomyces strains in the process of producing AFBs. A special focus was placed on the fate of the volatile and non-volatile compounds during the fermentation and their correlations with the sensory properties of the AFBs. The goal was to produce new knowledge about the potential of producing AFBs of high quality and providing technical guidance for the beverage industry. Furthermore, this study promotes the exploitation of Finnish local apple and pear cultivars for commercial utilization in beverage processing. In Studies I & II, the volatile and non-volatile compounds and sensory quality of alcoholic apple beverages were evaluated. The alcoholic beverages were made from selected Finnish traditional and local apple cultivars Saccharomyces cerevisiae and Schizosaccharomyces pombe yeasts without any added carbon sources. The sugars, organic acids, volatile compounds, and phenolic compounds as well as the ethanol and glycerol content were measured using chromatographic and mass spectrometric methods before and after the fermentation. The sensory differences among selected fermented beverages were analyzed using check-that-all-apply tests with untrained panelists. In general, alcoholic fermentation enhanced the contents of the higher alcohols, aldehydes, and acetals but decreased the concentrations of phenolic compounds. Cultivar and yeast selections both significantly influenced the chemical compositions and sensory properties of the obtained beverage products. The utilization of S. pombe significantly decreased the malic acid, and these apple beverages were shown to be less sour when compared to beverages fermented with S. cerevisiae. Moreover, p-coumaric, caffeic, and 5-O-caffeoylquinic acids, as well as procyanidin dimers were shown to be potential contributors to the mouth-drying and puckering astringency in the alcoholic apple beverages. In Studies III & IV, compositions of phenolic compounds, sugars, organic acids and certain volatile compounds in juices and perries made from unreleased breeding selections and cultivars of the European pear were evaluated. In general, the chemical profiles of the pear juices are primarily dependent on the genetic background, but the effects are complex. Breeding selections sharing the same parental cultivars varied significantly among the cultivars. The ‘putative dessert pear’ group (determined by the breeders) contained more analyzed volatile compounds, whereas the ‘putative perry pear’ group was closely associated with the quinic acid derivatives of caffeoyl and coumaric acids and coumaric acid, in addition to (+)-catechin and procyanidin dimers. In Study IV, yeast strains of Saccharomyces cerevisiae and Torulaspora delbrueckii were used to produce fermented pear beverages from the selected pear fruits from Study III. The sensory characteristics, the chemical profiles of the alcoholic beverage products and the initial pasteurized juices were analyzed using a trained panel. For the alcoholic pear beverages, the fermentation process reduced the content of hydroxybenzoic acids, procyanidins, and flavonols, in addition to increasing the content of flavan-3-ols and hydroxycinnamic acids. The utilization of T. delbrueckii led to higher ‘cooked pear’ and ‘floral’ odors when compared with S. cerevisiae fermentations. Moreover, certain derivatives of hydroxybenzoic and hydroxycinnamic acid, flavan-3-ols, procyanidins, and flavonols were closely correlated with astringency whereas sorbitol associated with sweetness in the fermented pear beverages.
Source: UTUPub (University of Turku)
Author: He, Wenjia
Language: English
Subfield: Food Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W7064680513