The influence of selected indigenous yeasts on Pinot Noir wine colour properties.

BACKGROUND: The use of indigenous selected starters in winemaking is gaining interest due to certain advantages for the sensory quality of the wine. The present work shows the results of a laboratory experiment in which the influence of selected indigenous yeasts on the colour characteristics of Pinot Noir was studied with the use of high hydroxycinnamate decarboxylase activity yeasts. Pichia guilliermondii ZIM624 and Wickerhamomyces anomalus S138 yeasts were used in sequential fermentation with two strains of Saccharomyces cerevisiae, the native ZIM2180 strain and commercial Fermol Premier Cru (FPC). RESULTS: In co-inoculation fermentations, non-Saccharomyces yeasts decreased colour intensity (on average by 25.5%). In wines fermented with ZIM624, the concentration of vinylphenolic pyranoanthocyanins increased (average concentration 1.5 mg L-1 ). However, vitisin concentration was significantly higher in S138 + FPC fermentation (1.3 mg L-1 and an average of 0.9 mg L-1 , respectively). Pinot Noir wines fermented with only ZIM2180 and sequential inoculation of ZIM624 + ZIM2180 resulted in significantly higher colour intensity (6.1 ± 0.0 AU and 4.4 ± 0.0 AU, respectively) and lower wine hue parameters compared to other wines. Sensory evaluation also showed that both wines had the highest perceived colour intensity and purple colour suggesting improvement in wine quality parameters. CONCLUSIONS: The results confirmed that selected indigenous starters made out of Saccharomyces and non-Saccharomyces yeasts can alter Pinot Noir wine colour parameters and improve wine colour properties. Those yeasts properties should be investigated prior to the development of new commercial starters but also be considered in large scale spontaneous fermentations of low colour intensity red wines like Pinot Noir. © 2021 Society of Chemical Industry.

Polyphenol, antioxidant and antimicrobial potential of six different white and red wine grape processing leftovers.

BACKGROUND: During winemaking, grape polyphenols are only partly extracted, and consequently unexploited. The main aim was to characterize the phenolic content of freeze-dried grape skin and seed (FDSS) extracts obtained from Slovenian and international grape varieties and to evaluate their antioxidant, antimicrobial and anti-adhesive activities. RESULTS: FDSS of six Vitis vinifera L. grapevine cultivars from Vipava Valley region (Slovenia) underwent extraction and sonification under different conditions. Flavonols were the predominant content of extracts from white 'Zelen' and 'Sauvignon Blanc' grape varieties, with strong antimicrobial activities against Gram-negative bacteria. 'Pinot Noir' FDSS extracted with 50% aqueous ethanol extraction produced a high phenolic content in the final extract, which was further associated with strong antioxidant and antimicrobial activities against all tested bacteria. Bacterial adhesion to stainless steel surfaces with minimal and maximal surface roughness was significantly inhibited (up to 60%) across a wide FDSS concentration range, with lower concentrations also effective with two types of stainless steel surfaces. CONCLUSION: FDSS extracts from winery by-products show interesting phenolic profiles that include flavonols, catechins, anthocyanins and hydroxycinnamic acids, with yields influenced by grapevine cultivar and extraction conditions. The antioxidant, antimicrobial and anti-adhesive activities of 50% aqueous ethanol 'Pinot Noir' FDSS extract reveals potential applications in food, pharmaceutical and cosmetic industries for these bioactive residues. © 2016 Society of Chemical Industry.

Isotopic and elemental characterisation of Slovenian apple juice according to geographical origin: Preliminary results.

This study examined the applicability of stable isotope and multi-element data for determining the geographical origin of fresh apple juices. Samples included three apple cultivars (Idared, Golden Delicious and Topaz) harvested in 2011 and 2012 from five different geographical regions of Slovenia. Regional discrimination of the juice samples was most successful when using linear discriminant analysis (LDA) and taking into account the following parameters: δ(2)H and δ(18)O content of juice water; δ(15)N and δ(13)C content of the pulp, (D/H)I and (D/H)II in ethanol and the concentration of S, Cl, Fe, Cu, Zn and Sr. Overall prediction ability was 83.9%. The factors that best distinguished the different types of cultivar were the δ(2)H and δ(18)O content of fruit juice water; the δ(13)C and (D/H)I content of ethanol; and the concentration of S, Mg, K, Cu, and Ti. Prediction ability, taking into account all ten parameters, was 75.8%.

Ultrasonic extraction of phenols from olive mill wastewater: comparison with conventional methods.

Recovery of phenols from olive mill wastewater (OMWW) was studied, comparing five sample preparation methods: filtration, solid-phase (SPE), liquid-liquid (LLE) and ultrasonic (US)-assisted extraction of liquid and solid (freeze-dried) OMWW. Results showed that ultrasonication is a good alternative to conventional solvent extractions, providing higher recoveries at both levels of individual and total phenol yields. Sonication of liquid OMWW in organic solvent was more efficient vs its nonassisted counterpart (agitation), but did not provide a representative phenol chromatogram due to ethyl acetate use. By contrast, the US-assisted extraction of freeze-dried OMWW (3 × 20 min) in 100% methanol (1.5 g/25 mL, w/v) offered the highest qualitative-quantitative phenol yields without any US-induced alterations. Moreover, freeze-drying is an excellent preservation of initial liquid OMWW, holding a great potential for delayed analysis. This study is also the first report that Slovenian OMWW may be utilized as a valuable source of phenols, especially hydroxytyrosol and tyrosol.