Enzymatic Removal of Off-flavors from Apple Juice

Abstract

Contaminating microorganisms such as Actinomycetes, Alicyclobacillus, and Chlostridium can generate off-flavors in apple juices. Such bacterial metabolites represent, besides phenol types such as guaiacol and 2,6-dibromophenol, a broad range of other chemicals, for example, geosmin, 2-methylisoborneol, or alpha-terpineol. A laccase from Trametes hirsuta was purified, immobilized, and applied for the selective elimination of off-flavor substances in apple juice caused by microbial contamination. The evaluation using GC-MS showed that enzymatic treatment could reduce the amount of guaiacol and 2,6-dibromophenol in apple juice significantly by 99 and 52%, respectively. Upon addition of mediators, the degradation could be increased and the spectrum of substrates extented. Furthermore, commercial apple juices spiked with off-flavors were treated in a continuous-flow reactor and tested by sensory evaluation.

Laccase oxidation and removal of toxicants released during combustion processes

“…This remarkable ability of laccases has found widespread application ranging from effluent treatment, bioremediation of water and soil contaminated with xenobiotics to removal of bitter polyphenols from beverages. For example, phenolic removal by laccase proved useful in the production and treatment of beverages (wine, fruit juice and beer) (Brenna and Biachi, 1994;Schroeder et al, 2008). Laccase has been shown to oxidize, polymerize, and detoxify urushiol and many other phenolic based pollutants (Xu, 1999;Ri-He et al, 2008;Nyanhongo et al, 2002Nyanhongo et al, , 2006aNyanhongo et al, and b, 2007.…”

Preparation of immobilized Trametes pubescens laccase on a cryogel-type polymeric carrier and application of the biocatalyst to apple juice phenolic compounds oxidation

“…It is worthwhile to mention that according to literature [18], immobilized laccase leads to improvement of apple juice quality also by eliminating the oV-Xavor substances caused by microbial contamination.…”

“…Thus, the increase in stability by immobilization was successfully applied in a number of cases, some of them in connection with food applications [15][16][17][18][19].…”

A New Sensory Approach Combined with a Text-Mining Tool to Create a Sensory Lexicon and Profile of Monovarietal Apple Juices

“…A list of descriptors was developed with a text-mining process, using the R package "tm" [13]. The "Material and Methods" and "Results and Discussion" sections of 17 peer-reviewed papers [2,5,8,[14][15][16][17][18][19][20][21][22][23][24][25][26][27] related to sensory analysis of apple juice from 1998 to 2018 were selected from the Scopus database to be the "corpus" of the text-mining computation. Before texts could be assessed, a preprocessing step was necessary to reduce the amount of useless information of the corpus and transform the text into "tokens" (units of text such as words).…”