Modulation of Papaya Wine Flavour Compound Formation by Yeasts

Ph.DDOCTOR OF PHILOSOPH

Utjecaj prekurzora na hlapljive sastojke vina dobivenog fermentacijom soka papaje pomoću mješovite kulture kvasaca

The impact of the addition of fusel oil or amino acids on the volatile compounds in papaya wine fermented with a mixed culture of Saccharomyces cerevisiae var. bayanus R2 and Williopsis saturnus var. mrakii NCYC 2251 at a ratio of 1:1000 was studied. Fusel oil addition increased the fraction of alcohols and promoted the production of isoamyl octanoate, isoamyl decanoate and isobutyl decanoate, while decreased the fraction of ethyl acetate and 2-phenylethyl acetate. The addition of amino acids enhanced the formation of total volatile fatty acids, 2-phenylethanol and some ethyl esters. The papaya wine with added amino acids possessed more acidic and buttery notes than the control, while that with added fusel oil had an overall aroma profile comparable to that of the control. This study suggests that papaya juice fermentation with mixed yeasts in conjunction with the added fusel oil or selected amino acids may be another method of modulating the flavour of papaya wine.U ovom je radu ispitan utjecaj dodatka patočnog ulja ili aminokiselina na hlapljive sastojke vina dobivenog fermentacijom soka papaje pomoću mješovite kulture kvasaca Saccharomyces cerevisiae var. bayanus R2 i Williopsis saturnus var. mrakii NCYC 2251 u omjeru 1:1000. Dodatkom patočnog ulja povećan je udjel alkohola, te je poboljšana proizvodnja izoamilnog oktanoata, izoamilnog dekanoata i izobutilnog dekanoata, dok je smanjen udjel etilnog acetata i 2-feniletilnog acetata. Nastanak hlapljivih masnih kiselina, 2-feniletanola i nekih etilnih estera pospješen je dodatkom aminokiselina. U usporedbi s kontrolnim uzorkom, vino proizvedeno fermentacijom papaje uz dodatak aminokiselina imalo je izraženiju kiselu i putrastu notu, dok se aroma vina kojem je dodano patočno ulje nije razlikovala. Ovo je istraživanje pokazalo da se fermentacijom soka papaje pomoću mješovite kulture kvasaca uz dodatak patočnog ulja ili odabranih aminokiselina može promijeniti aroma vina

Modulation of grape wine flavor via the sequential inoculation of <i>Williopsis saturnus</i> and <i>Saccharomyces cerevisiae</i>

<p>The effects of the inoculum ratio of <i>Williopsis saturnus</i> var. <i>saturnus</i> NCYC22 and <i>Saccharomyces cerevisiae</i> var. <i>bayanus</i> EC-1118 at 1:200 and 1:800 on the chemical and volatile compositions of grape wine were studied in sequential fermentation. The grape juice was first inoculated with <i>Williopsis (W.) saturnus</i> for 9 d; thereafter, <i>Saccharomyces (S.) cerevisiae</i> was inoculated to continue the fermentation until d 19. The cell population of <i>W. saturnus</i> disappeared by d 13, with <i>S. cerevisiae</i> dominating until the end of the fermentation in both inoculum ratios. The changes in yeast count, pH, total soluble solids, sugars, organic acids, and amino acids were similar between the two inoculum ratios. A range of volatile compounds was formed, including alcohols, esters, fatty acids, aldehydes, and terpenes. There were significant differences between both inoculum ratios for medium-chain fatty acids (C8, C10, and C12), ethyl esters of fatty acids of C6, C10, C12, and C14 as well as isoamyl octanoate, while other volatiles were statistically the same.</p

Modulation of grape wine flavor via the sequential inoculation of Williopsis saturnus and Saccharomyces cerevisiae

10.1080/08905436.2017.1369434Food Biotechnology314245-26

The Possible Reduction Mechanism of Volatile Sulfur Compounds during Durian Wine Fermentation Verified in Modified Buffers

Durian fruit is rich in volatile sulfur compounds (VSCs), especially thiols and disulfides, which contribute to its onion-like odor. After fermentation, these VSCs were reduced to trace or undetectable levels in durian wine. The possible reduction mechanism of these VSCs (especially diethyl disulfide and ethanethiol) was investigated in a modified buffer in the presence of sulfite at different pH. An interconversion between diethyl disulfide and ethanethiol was found to be dependent on the pH: the higher the pH, the higher production of ethanethiol. It is suggested that, during durian wine fermentation, disulfides endogenous to durian pulp might be firstly converted into their corresponding thiols in the presence of reductant sulfite formed by yeast. The produced thiols as well as the thiols endogenous to the durian pulp were then removed by the mannoproteins of yeast lees