The chemical and microbiological changes during spontaneous <italic>budu</italic> fermentation were elucidated on monthly basis (1–12 months). A significant increase (P<0.05) in pH, acidity, soluble protein, total protein, and moisture content was observed during <italic>budu</italic> fermentation, except for the fat content. The total microbial load decreased gradually from the initial of 6.13±0.01 to 3.45±0.13 log CFU g−1 after 12 months of fermentation. Overall, 150 isolates were identified, with a majority of bacteria (77%), followed by yeasts (12%) and 11% of unconfirmed species. Micrococcus luteus was the predominant strain that initiated the fermentation before it was replaced by Staphylococcus arlettae that exists throughout the fermentation. This study confirmed that lactic acid bacteria and yeasts often coexist with other microorganisms, even though a microbiological succession usually takes place both between and within species, which shaped the chemical and sensory characteristics of the final product. In addition, some of the isolates could be potentially valuable as starter cultures for further improved and controllable <italic>budu</italic> fermentation.
The sensory quality of red wines is basically determined by the colour, which depends on the amount and on the evolution of anthocyanins and other phenolic compounds extracting from the berries into the wine during wine-making. The anthocyanin-monomers are responsible for the development of the red colour, and their acylated derivatives provide stability for the colour of the wines. The anthocyanin profile of wines is affected by several factors: the grape variety, the conditions during wine-making, and also the yeast culture used for the fermentation. In our experiments a self-compiled model solution was fermented by spontaneous fermentation, as well as by four commercial yeasts under laboratory conditions. After fermentation total polyphenolics, anthocyanins, anthocyanin monomer profile, colour intensity, hue, and the ratio of polymeric anthocyanins were studied. Our results show that the spontaneous yeast fermentation resulted in a higher anthocyanin concentration in the fermented model solution, but the commercial yeast strains provided a more advantageous colour characteristic compared to the spontaneous fermentation. After the spontaneous fermentation less sediment was left than in the commercial yeast fermented samples.
Initiated by the Association “Wine Route of Etyek Wine District”, the objectives of this study were to isolate and identify autochthonous yeast strains from local wines and to determine their oenologically important properties. The first aim of this work was to characterize the taxonomic and phenotypic diversity of the representative Saccharomyces yeast strains that dominate the spontaneous fermentations in this wine district. The results obtained by molecular ribotyping (ARDRA) revealed a strong dominance of S. cerevisiae, but S. bayanus var. uvarum was also present sporadically. Some of the natural isolates exhibited high volatile acid production or poor fermentation capacity, which imply a quality risk in spontaneous fermentations. Most of the isolates, however, displayed good oenological features during lab scale fermentations. As the second aim of this work, the most promising, selected strains were further tested for oenological properties in microvinification scale and, finally, in large scale fermentations. The analytical and sensory analysis proved that selected strains, including S. bayanus var. uvarum, can be used as local starter cultures, which may contribute to the typicality of the local wines in comparison with commercial starters.
In this study the role of different yeast strains in the production of volatile flavour components of Tokaji Aszú wine was tested. The effect of a Saccharomyces cerevisiae starter and that of the typical endogenous Candida stellata strain as well as spontaneous fermentation were studied and compared. For the fast comparison of aroma profile, a solid phase microextraction (SPME) sampling and a GC-MS separation and identification were used. Thirty of the present compounds were selected to characterise the changes of flavour. Significant differences were found between wines fermented with different yeast strains. Application of a Saccharomyces cerevisiae starter alone accelerated the fermentation but this caused only little change in the aroma profile and content. Candida stellata contributed weakly to the production of aroma, especially to that of the longer carbon chain ethyl esters. Characteristic compounds of aged wine were detected in bottle aged Tokaji Aszú. The change of aroma profile as a function of bottle storage time was studied. The concentrations of vitispirane, trimethyl dihydronaphtalene, 2-phenylethanol and diethyl succinate increased in the course of ageing time, while those of 3-methyl-butyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate and ethyl dodecanoate decreased.
Hydrostatic Pressure and Ultraviolet Light treatment, and spontaneousfermentation of oyster mushrooms. Materials and methods Pretreatments and fermentation The fresh oyster mushroom ( P . ostreatus ) utilised in this research was supplied from a local market
: spermidine; E: spermine; F: isoamylamine (1: sedimented must, inoculated alcoholic fermentation without malolactic fermentation; 2- non-sedimented must, spontaneousfermentation with spontaneous malolactic fermentation) The results of the present study showed
), kimchi ( Rhee et al., 2011 ) and sauerkraut ( Halász et al., 1999; Leroy and De Vuyst, 2004 ). Traditionally, many of the fermented foods are produced under spontaneousfermentation, however, by the application of Lactobacillus strains – which have good