Patricia Paneque

Volatile and sensory profile of organic red wines produced by different selected autochthonous and commercial Saccharomyces cerevisiae strains.

Organic wines were produced at pilot scale to select the best autochthonous and commercial yeast strains to obtain wines with high organoleptic qualities. We tested the behaviour of five S. cerevisiae yeast strains and determined their volatile composition and organoleptic characteristics by sensory analysis. A total of 51 volatile compounds were quantified in the wines produced. The concentration of most of the volatile compounds was significantly influenced depending on which yeast strain was inoculated. The differences observed in the volatile composition of the wines appear to be quantitative rather than qualitative. In general, acetals were the most abundant group of volatile compounds in all the samples studied, followed by alcohols without ethanol. The highest contents of volatile compounds were found in two of the wines produced by autochthonous yeast strains. The results obtained in the sensory analysis suggest that autochthonous yeast produced wines of higher organoleptic quality because this sample gave the highest value for the general impression attribute.

Effect of the use of commercial Saccharomyces strains in a newly established winery in Ronda (Malaga, Spain)

An ecological study of the yeasts present in a spontaneous and an inoculated fermentation in red wine was carried out in 2005 vintage in a winery located in the Denomination of Origin “Sierras de Málaga” (Málaga, southern of Spain). The winery operated by the first time with the 2003 vintage and since then, has used commercial yeast inocula to start alcoholic fermentation. Yeast isolates were identified by PCR-RFLP analysis of the 5.8S-ITS region from the ribosomal DNA and by mitochondrial DNA RFLP analysis. Except for non-Saccharomyces yeasts found in the fresh must before fermentation, all the isolates were found to be commercial Saccharomyces cerevisiae strains employed by the winery during the successive vintages; thus, no indigenous Saccharomyces yeasts were isolated during fermentation. The same four restriction patterns were found in non inoculated and inoculated vats, although with different frequencies. The use of commercial yeast starter in a new established winery seems to have prevented the development of a resident indigenous Saccharomyces flora.

Monitoring volatile compounds production throughout fermentation by Saccharomyces and non- Saccharomyces strains using headspace sorptive extraction

Currently, there is a growing interest in the use of non-Saccharomyces yeast to enhance the aromatic quality of wine, with pure or mixed cultures, as well as sequential inoculation. Volatile components of wines were closely related to their sensory quality. Hence, to study the evolution of volatile compounds during fermentation was of great interest. For this, sampling methods that did not alter the volume of fermentation media were the most suitable. This work reports the usefulness of headspace sorptive extraction as non-invasive method to monitor the changes in volatile compounds during fermentation. This method allowed monitoring of 141 compounds throughout the process of fermentation by Saccharomyces cerevisiae and Lachancea thermotolerans strains. Both strains showed a similar ability to ferment a must with high sugar content. The S. cerevisiae strain produced higher amount of volatile compounds especially esters that constitutes fruity aroma than L. thermotorelans.

Influence of Saccharomyces cerevisiae and Lachancea thermotolerans co-inoculation on volatile profile in fermentations of a must with a high sugar content

The aim of this work was to evaluate how the use of mixed cultures of Saccharomyces cerevisiae and Lachancea thermotolerans indigenous yeast strains influences the volatile composition of wine. Multivariate curve resolution (MCR) method has been applied to data analysis. Five fermentation trials were carried out: three co-inoculated with L. thermotolerans:S. cerevisiae, at the ratio of 50:1, 20:1 and 5:1 respectively, and two with a pure culture of each strain. A must from sun-dried Pedro Ximénez grapes was employed. Volatile composition was determined by dual sequential stir bar sorptive extraction, followed by GC-MS analysis. MCR provided 171 peaks. Results in co-inoculation fermentations revealed that the majority compounds obtained in each case followed the same trend as that observed for the pure culture of the strain that was present in a higher proportion. Finally, 50:1 and 20:1 seemed to be the best proportions to obtain a wine with a quality volatile profile.

Soil hydraulic properties as the main driver in the establishment of biomass crops in contaminated soils

In recent years increasing attention has been given to the potential use of contaminated lands for biofuel production, because these degraded soils cannot be used for food production. To establish these crops in Mediterranean contaminated areas, where the soil quality is usually very poor, the addition of soil amendments might be necessary to improve soil productivity. In addition, the use of crops with low water demands, adapted to these particular conditions of climate and soil contamination, is a key requirement. We studied the development of Cynara cardunculus and Silybum mariamun crops (both suitable for the production of biomass for biofuel uses under a Mediterranean climate) in trace element contaminated soils under field conditions. To our knowledge, this is the first such work under these particular experimental conditions (soil contamination and field trial). Soil physical (hydraulic), chemical, and biochemical properties were monitored for one year in experimental plots, where we tested the effects of the addition of two different amendments (sugar lime and biosolid compost) on soil functioning and crop productivity. Seed germination and plant biomass production were low, although amendment addition improved both parameters. The chemical and biological indicators (enzyme activities, PLFA profiles, and soil respiration) tended to be slightly improved by the amendments, especially sugar lime. The hydraulic properties of the soil in the experimental area were very deficient, and the effect of the amendments was not enough to improve them; this was probably the main cause of the general low productivity of these rain-fed crops, as water infiltrated poorly through the root zone. To improve crop productivity under these soil conditions, certain aspects could be improved: higher doses of amendments should be applied and deeper tillage of the soil after amendment addition should be performed to facilitate water infiltration.

Production of biostimulants from okara through enzymatic hydrolysis and fermentation with Bacillus licheniformis: comparative effect on soil biological properties

ABSTRACT In this work okara (OK), a by-product of soy milk manufacturing, is submitted to an enzymatic hydrolysis and a fermentative process to produce different soil biostimulants (BS): EH, hydrolysate obtained by the enzymatic process; FHEB, fermentation broth with Bacillus licheniformis and the enzymes secreted during the fermentation; FHE, fermentation broth without bacteria and FH, the FHE hydrolysate in which enzymes were denatured. Enzymatic hydrolysates showed a different chemical composition compared with fermented hydrolysates and OK. It had a higher protein concentration as well as C, P and K. The proteins of OK were converted into peptides with a lower molecular weight, the fermented hydrolysates being those with the lowest molecular weight profile. The influences of hydrolysates and OK were tested in soil, finding that β-glucosidase, phosphatase and dehydrogenase activities were stimulated by every treatment. However, it was observed that EH produced a greater stimulation of dehydrogenase and phosphatase than both OK and fermented BS. The bacterial and fungal phospholipid fatty acids were also higher in soils amended with BS than those of the control and soils with OK. It has also been found that β-glucosidase, phosphatase and microbial biomass were dose-dependent in every treatment, but dehydrogenase only was dose-dependent in EH and OK treatments.

Obtaining edaphic biostimulants/biofertilizers from sewage sludge using fermentative processes. Short-time effects on soil biochemical properties

ABSTRACT In this manuscript, we study the manufacture and effect on soils of different edaphic biostimulants/biofertilizers (BS) obtained from sewage sludge using Bacillus licheniformis as biological tool. These BS consist of different combinations of organic matter, bacteria and enzymes that were subjected to several treatments. These BS were applied in soil in order to observe their influence on the biochemical properties (enzymatic activities and ergosterol content). Dehydrogenase, urease, β-glucosidase, phosphatase activities and ergosterol content were measured at different incubation days. Only dehydrogenase activity and ergosterol content were significantly stimulated after the application of BS1 and BS4. Rest of the extracellular activities were not stimulated probably because B. licheniformis practically has digested all organic substrates during fermentation process.