Ultrasound and microwave techniques for assisting ageing on lees of red wines

Ageing on lees is a slow process that carries microbiological and economic risks in the wineries. This study evaluates the possibility of enhancing the extraction of different compounds from the lees, using combined strategies, such as ultrasound (US) or microwaves (MW) and the addition of inactive dry yeasts (IDY), to reduce the lees ageing time. The complete chemical analysis of the wine was done, amino acids, polysaccharides, colour and volatile compounds, together with the sensory analysis. The combined treatments increased the release of total polysaccharides, mannoproteins and total monosaccharides in the wines, and some amino acids like proline. However, wines treated with US and MW, with and without lees, showed a decrease in tannins and colour intensity, and in some volatile compounds like fatty acid esters, acetates and terpenes. The wines treated with IDY and MW were the best valued for their floral and red berry flavours and less astringency.

Use of probiotic yeasts with biocontrol activity for fermentation of ewe's milk

BACKGROUND

There are sufficient scienctific studies that support the benefit that fermented dairy products produce in those who consume them. Traditionally, cow's milk has been the most commonly used milk but there is a growing interest in the development of new dairy products, substituting cow's milk with milk from other sources, as well as in the use of microorganisms in fermentation to replace artificial preservatives or treatments that may affect the chemical and organoleptic characteristics of the product. For these reasons, the aim of the present work was to understand the behavior of five potential probiotic yeasts during the fermentation of ewe's milk and to consider their potential use as biocontrol agents.

RESULTS

Saccharomyces cerevisiae 3 and Hanseniaspora osmophila 1056 provided the most promising kinetic parameters in the different salt, temperature and pH conditions tested in their technological characterization. The profiles of organic acids and volatile compounds after the fermentation period was noteworthy for contributing to the final aroma of the dairy product. Sensory analysis revealed the sour taste of all samples, and S. cerevisiae 3, Lachancea thermotolerans 1039, and H. osmophila 1056 stood out for an accentuated cheese flavor. In addition, all strains showed biocontrol activity; they reduced the mycelium of the mycotoxigenic molds.

CONCLUSION

Saccharomyces cerevisiae 3 and H. osmophila 1056 could be inoculated along with bacterial starters to provide a functional fermented beverage with improved flavor. These strains also have an added value as they act as biocontrol agents. © 2022 Society of Chemical Industry.

Power ultrasound treatment of Viognier grapes as a tool to increase the aromatic potential of wines

BACKGROUND

High-power ultrasound is a novel and non-thermal technique normally used in red vinification to increase the extraction of phenolic compounds. However, few studies have been carried out on its effect on the extraction of aroma compounds and their precursors in white grapes. This study evaluates the effect of high-power ultrasound at winery scale in the maceration of Viognier grapes on the content of varietal volatile compounds (free and glycosidically bound) in musts and wines, in comparison with wines from direct pressing and from short skin maceration.

RESULTS

The pre-fermentative ultrasound treatment of the grapes produced an increase in most of the varietal compounds of musts and wines, both in the free fraction and in the bound one, especially in the C6 alcohols, terpenes and norisoprenoids, some of them of sensory relevance, while the effect on esters and lactones was less evident. Ultrasound maceration allowed us to obtain wines of higher aromatic intensity, with a more pronounced varietal character.

CONCLUSION

The pre-fermentative ultrasound treatment of Viognier grapes increases the aromatic potential of the wines, as it favors the extraction of free and bound varietal volatile compounds. In addition, it allows the maceration time of the grapes to be reduced compared to conventional pre-fermentation techniques, thus avoiding oxidative processes that could negatively affect the aroma of the wines. © 2022 Society of Chemical Industry.

Corky off-flavor compounds in cork planks at different storage times before processing. Influence on the quality of the final stoppers

BACKGROUND

Cork companies store cork planks before processing them for a minimum of 6 months to dry up and to stabilize their texture and chemical composition, although many companies extend this storage period up to 12 months. However, there is no information about the influence of this seasoning period on their 'corky' off flavors. For this reason, the main compounds responsible for the 'cork taint' of planks stored before processing from 6 to 12 months were investigated.

RESULTS

Four haloanisoles and three halophenols were identified: 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA), pentachloroanisole (PCA), 2,4,6-tribromoanisole (TBA), 2,4,6-trichlorophenol (TCP), 2,3,4,6-tetrachlorophenol (TeCP), and 2,4,6-tribromophenol (TBP). All of the planks presented some haloanisole or halophenol after 6 and 9 months of storage, which practically disappeared after a year of storage. These compounds were only detected in the cork stoppers made from planks with 6 and 9 months of storage. Of the alkylmethoxypyrazines, 2-methoxy-3,5-dimethylpyrazine (MDMP), 3-isopropyl-2-methoxypyrazine (IPMP), and 3-isobutyl-2-methoxypyrazine (IBMP) were identified. The MDMP was detected in a larger number of planks with 6 months of storage and at higher concentrations than IPMP and IBMP. However, MDMP was not detected in the cork stoppers made from planks at 6, 9, and 12 months of storage.

CONCLUSION

A storage time of 6 months before processing of raw cork planks would be sufficient to obtain cork stoppers with low concentrations of corky off-flavor compounds. An increase in storage up to 9 or 12 months would result in practically 'cork taint'-free natural stoppers. © 2021 Society of Chemical Industry.

Potential of Different Natural Antioxidant Substances to Inhibit the 1-Hydroxyethyl Radical in SO2-Free Wines

The potential of different natural antioxidants to inhibit the 1-hydroxyethyl radical formation in SO₂-free wines was analyzed by electron paramagnetic resonance (EPR). Chitosan, glutathione, inactive dry yeast, oak and grape seed extracts, and ascorbic acid were tested in white and red wines. The ability of these substances to prevent the formation of acetaldehyde after the Fenton reaction and the oxygen consumption capacity were measured. Ascorbic acid was the antioxidant substance that offered higher percentages of 1-hydroxyethyl radical inhibition at 30 min of reaction. However, wines with ascorbic acid showed higher concentrations of acetaldehyde after the Fenton reaction. Grape seed extract and chitosan provided higher percentages of radical inhibition in red wine than those in white wine, in contrast to the inactive dry yeast that only produced radical inhibition in white wine. Although oak extract did not produce changes in the 1-hydroxyethyl radical, wines with that extract had lower concentrations of acetaldehyde.

Natural extracts from grape seed and stem by-products in combination with colloidal silver as alternative preservatives to SO2 for white wines: Effects on chemical composition and sensorial properties

The search for alternative additives to sulfur dioxide, with antioxidant and antimicrobial activity, in the production of wines is one of the current objectives of the enological industry. In the present study, aqueous extracts obtained from winery byproducts (grape seeds and stems), alone or in combination with colloidal silver complex, have been used in white vinification. The antimicrobial effect of the extracts was similar to that of sulfur dioxide, being more effective on lactic and acetic bacteria in those wines to which colloidal silver was added. The effect on the color, the phenolic compounds and the volatile fraction of the wines was evaluated, as well as their sensory profile. The use of both extracts modified the color of the wines, increasing the chromatic parameters a* and b*, indicating a browning tendency, although no other signs of oxidation were found. Wines with seed extracts contained higher amounts of flavan-3-ols, and a significant increase in some volatile compounds such as fatty acid ethyl esters and benzene compounds, which were identified in the extracts. From a sensorial point of view, the wines with stem extracts were the most similar to those elaborated with SO₂, detecting a certain bitterness in wines with seed extracts.

Oak wood extracts as natural antioxidants to increase shelf life of raw pork patties in modified atmosphere packaging

The use of antioxidants and refrigeration storage in modified atmosphere packaging, MAP, are the main strategies to slow down the oxidative and microbial deterioration of fresh meat. Synthetic antioxidants are commonly used for this purpose, however due to their controversial health effects, natural alternatives for their replacement are being looked for. The main aim of this work is the evaluation of pressurised aqueous extracts from oak wood as natural preservative of pork patties. The effect of different amounts of oak wood extracts (0.05, 0.5 and 1.0%) on the self-life of pork patties packed in MAP in refrigeration during 12 days were studied in comparison with the use of sodium ascorbate as synthetic preservative. Samples treated with oak wood extracts showed lower lipid oxidation, higher antioxidant capacity and an inhibitory effect on the enterobacteria growth. Furthermore, the addition of oak wood extracts resulted in a dramatically decrease of the volatile compounds coming from the lipid oxidation reactions. On the other hand, it is noteworthy that the use of oak wood extracts modified sensorial characteristics. Intensity colour was higher and new sensorial features such as oak wood and sweet spices appeared which were well appreciated.

Alternative amendment for vineyards from by-products of pyro-bituminous shale: Effect on wine amino acids and biogenic amines

With the aim of looking for a model of agroecological production, the use of by-products from pyro-bituminous shale as amendment, and its effect on wine amino acids and biogenic amines has been evaluated. Field trials aimed to compare the effect of different doses of conventional and limestone shale from by-products of pyro-bituminous. Four replicates for six different fertilization treatments were arranged in a split plot design during 2009/2010 and 2010/2011 vintage. A chromatographic analysis was carried out to evaluate the impact of fertilization treatments on the amino acid and biogenic amine content of wines produced. Results showed few significant differences among fertilization treatments tested according to the amino acids composition of wines, although it seemed that a combination of conventional and pyro-bituminous shale could be the best option. By-products of pyro-bituminous shale seem to be a good partial substitutive amendment for Brazilian vineyards. This research seems to be a new approach for sustainable revalorization of domestic fertilizers to enable minor environmental impacts and lower production costs without detriment to quality.

Cyclic polyalcohols: fingerprints to identify the botanical origin of natural woods used in wine aging

Cyclic polyalcohol composition of 80 natural wood samples from different botanical species, with the majority of them used in the oenology industry for aging purposes, has been studied by gas chromatography-mass spectrometry (GC-MS) after its conversion into their trimethylsilyloxime derivatives. Each botanical species showed a different and specific cyclic polyalcohol profile. Oak wood samples were characterized by the richness in deoxyinositols, especially proto-quercitol. Meanwhile, other botanical species showed a very low content of cyclic polyalcohols. The qualitative and quantitative study of cyclic polyalcohols was a useful tool to characterize and differentiate woods of different botanical origin to guarantee the authenticity of chips used in the wine-aging process. Monosaccharide composition was also analyzed, showing some quantitative differences among species, but cyclic polyalcohols were the compounds that revealed the main differentiation power.

Effect of freeze-drying and oven-drying on volatiles and phenolics composition of grape skin

Grape skins are the part of the fruit with the highest amount of volatile and polyphenolic compounds. Volatile compounds give the fruit and other grape derivatives their flavour. Polyphenolic compounds are responsible for the colour of the fruit, juice and wine, and also act as very important natural antioxidant compounds. Dehydration is a method used to prevent the damage of these compounds over time. Nevertheless, in the case of volatile compounds, removing water can cause compound degradation or the evaporation of such compounds. This work studied two drying methods, freeze-drying and oven-drying, at 60 degrees C, as skin preservation methods. The skins from two grape varieties, Carménère and Cabernet Sauvignon, were dried. Many volatile compounds, which are of interest in the aroma profile, were identified in both varieties as terpenes (linalool, etc.), sesquiterpenes (farnesol), norisoprenoids (vitispirane, etc.), C(6) alcohols (1-hexanol, etc.), etc., and their amount decreased significantly with the oven-drying method, in contrast to the freeze-drying method. Both phenolic compounds, anthocyanins and flavonols, were identified in fresh and dehydrated samples, thus resulting in the freeze-drying method being less aggressive than oven-drying methods.

Influence of storage conditions on chemical composition and sensory properties of citrus honey

Fresh citrus honey was stored at 10, 20, and 40 degrees C for 12 months. The effect of storage on the quality of honey was evaluated using physicochemical parameters, volatile compounds, mono-, di-, and trisaccharides, and sensory analysis. Diastase activity and HMF were out of the legal limit in honey stored 12 months at 40 degrees C. Volatile compounds (especially terpenes and terpene derivatives), monosaccharides, and disaccharides presented important losses during honey storage at any temperature. Honey storage at 10 or 20 degrees C maintained their floral, fresh, citric, and fresh fruit aroma, while the intensities of these attributes were diminished. Storage at 40 degrees C during 12 months resulted in the appearance of attributes such as "medicinal, smoked, toasted, cooked vegetable, and ripened fruit", associated with compounds formed during the Maillard reaction or through degradation of sugars such as volatile pyrroles, furanones, pyranones, and pyrazines, which appeared or increased in concentration during honey storage mainly at high temperature.

Comparison of the volatile composition of wild fennel samples (Foeniculum vulgare Mill.) from central Spain

Comparison of the volatile composition of fennel (Foeniculum vulgare Mill.) has been carried out using direct thermal desorption (DTD) coupled to gas chromatography-mass spectrometry. Forty-two wild fennel stem samples were collected in two different geographical areas of Central Spain. DTD allowed a high recovery of volatiles from small sample sizes without thermal decomposition. trans-Anethole was the main volatile compound for most cases, although a high variability was found among samples, showing clear phytochemical differences.

Volatile composition and contribution to the aroma of spanish honeydew honeys. Identification of a new chemical marker

Honeydew honeys from holm-oak, oak, and forest were isolated for aroma compounds by simultaneous distillation-extraction and analyzed by gas chromatography-mass spectrometry. In all, 66 volatile components were identified and quantified. trans-Oak lactone, a characteristic volatile component of oak wood, is proposed as a new chemical marker for the plant origin of honeydew honeys. Other compounds, such as aminoacetophenone and propylanisol, could be considered characteristic of holm-oak honeydew honeys. A total of 15 volatile compounds presented odor activity values (OAVs) greater than 1, with phenylacetaldehyde and beta-damascenone being those with the highest OAVs.

Influence of the species and geographical location on volatile composition of Spanish oak wood (Quercus petraea Liebl. and Quercus robur L.)

The influence of the species and geographical origin on the volatile composition of wood samples from 80 Spanish oaks (55 Quercus petraea Liebl. and 25 Quercus robur L.) has been studied. Oak volatile components were isolated by simultaneous distillation-extraction and analyzed by gas chromatography-mass spectrometry. cis- and trans-beta-methyl-gamma-octalactones were the main constituents, the cis stereoisomer being predominant. Other important volatile components were furfural, 5-methylfurfural, guaiacol, eugenol, vanillin, or syringaldehyde. The main differences were established between species, Quercus petraea being significantly richer in volatile compounds than Quercus robur; however, the variability found among trees was high. Differences among geographical provenances were much less important than those found between species.

Volatile components and key odorants of fennel (Foeniculum vulgare Mill.) and thyme (Thymus vulgaris L.) oil extracts obtained by simultaneous distillation-extraction and supercritical fluid extraction

Volatile oil extracts of fennel seeds (Foeniculum vulgare Mill.) and thyme leaves (Thymus vulgaris L.) were obtained by simultaneous distillation-extraction (SDE) and supercritical fluid extraction (SFE) and analyzed by gas chromatography-mass spectrometry (GC-MS). In general, fennel oil extracted by SDE and SFE showed similar compositions, with trans-anethole, estragole, and fenchone as the main components. In contrast, thymol and p-cymene, the most abundant compounds in thyme leaves, showed big differences, with generally higher amounts of monoterpenes obtained by SDE. However, in this case, the differences between the extracts were higher. Key odorants of fennel seeds determined by gas chromatography-olfactometry (GC-O) showed similar patterns when applying SDE and SFE. trans-Anethole (anise, licorice), estragole (anise, licorice, sweet), fenchone (mint, camphor, warm), and 1-octen-3-ol (mushroom) were the most intense odor compounds detected in fennel extracts. Thymol and carvacrol, with oregano, thyme, and spicy notes, were identified as key compounds contributing to the aroma of thyme leaves.

Formation pathways of ethyl esters of branched short-chain fatty acids during wine aging

The particular behavior during wine aging of fermentative branched fatty acid ethyl esters, related to yeast nitrogen metabolism, compared that of their straight-chain analogues, related to yeast lipid metabolism, was first checked in 1-5 year aged Muscadet wines. Quantitative SIDA measurements showed that the levels of the former increased, whereas those of the latter decreased. Then, three hypothetical pathways suggested in the literature to explain these variations of branched esters were investigated. Two Muscadet and Sylvaner wines were spiked with levels of deuterated isobutanoic acid and its ethyl ester, similar to those of their natural analogues, then they were submitted to model aging. Quantitative SIDA measurements on the formation of these natural and labeled ethyl esters from the corresponding acids revealed that the behavior of the natural and labeled compounds were similar. The acid levels were much higher than the ester levels in the initial young wine, and a significant upward trend of their esterification ratios to those of the acid-ester equilibrium was observed with aging. Thus, this equilibrium proved to be the most effective in generating the branched fatty acid ethyl esters during wine aging. In contrast, the formation of these acids by Strecker-type degradation of wine amino acids in the conditions of the model aging or by hydrolysis of their glycoconjugates proved to be ineffective.

Fast screening method for volatile compounds of oak wood used for aging wines by headspace SPME-GC-MS (SIM)

A headspace solid-phase microextraction (HS-SPME) method is proposed for analyzing the main volatile components from a sensory standpoint (furfural, oak lactones, eugenol, vanillin, and syringaldehyde) present in nontoasted and toasted oak wood of different origins. To maximize the yield of compounds extracted from wood chips and to obtain a good precision of the method, the most important variables affecting HS-SPME have been studied. The best results were obtained when the sample was heated at 70 degrees C and the headspace extracted for 40 min with a DVB/CAR/PDMS fiber, which gave the overall best recovery. The values for the repeatability ranged from 6.4 to 7.8%, and those for the reproducibility from 5.4 to 8.7%. The precision of the results obtained makes the proposed technique appropriate for its use in characterizing oak wood samples of different origins and in the selection of the most suitable oak wood to age wines and spirits, on the basis of the chemical composition of the wood samples.

Influence of drying on the flavor quality of spearmint (Mentha spicata L.)

Spearmint (Mentha spicata L.) was dried using three different drying methods: oven-drying at 45 degrees C, air-drying at ambient temperature, and freeze-drying. The effect of the drying method on the volatile compounds and on the structural integrity and sensory characteristics of the spice was evaluated. The volatile components from fresh and dried spearmint samples were isolated by simultaneous distillation-extraction (SDE) and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 28 compounds were identified, carvone, limonene, and 1,8-cineole, in that order, being the main components in all of the samples. Oven-drying at 45 degrees C and air-drying at ambient temperature were the methods that produced the best results. An increase in monoterpenes was observed in all of the dried samples, except in the freeze-dried samples that underwent freezing at -198 degrees C. Freeze-drying resulted in substantial losses in oxygenated terpenes and sesquiterpenes. The effect of each drying method on leaf structure was observed by scanning electron microscopy. From a sensory standpoint, drying the spearmint brought about a decrease in herbaceous and floral notes together with an increase in minty odor.

Effect of drying method on the volatiles in bay leaf (Laurus nobilis L.)

The effect of different drying treatments on the volatiles in bay leaf (Laurus nobilis L.) was studied. Simultaneous distillation extraction (SDE) and solid-phase microextraction (SPME) were compared by gas chromatography-mass spectrometry (GC-MS) of the volatile components in bay leaves. SDE yielded better quantitative analysis results. Four drying treatments were employed: air-drying at ambient temperature, oven-drying at 45 degrees C, freezing, and freeze-drying. Oven drying at 45 degrees C and air-drying at ambient temperature produced quite similar results and caused hardly any loss in volatiles as compared to the fresh herb, whereas freezing and freeze-drying brought about substantial losses in bay leaf aroma and led to increases in the concentration levels of certain components, e.g., eugenol, elemicin, spathulenol, and beta-eudesmol.

Supercritical carbon dioxide extraction of volatiles from spices. Comparison with simultaneous distillation-extraction

Supercritical fluid extraction (SFE) and simultaneous distillation-extraction (SDE) were used to extract the essential oils from three different spices (oregano, basil, and mint), and a comparative study of extracts obtained using SFE and SDE is presented. Temperature and pressure for the SFE extraction were optimized prior to the experimental extractions. The extracts obtained using the two methods were very similar in composition, but SFE yielded better relative standard deviations and avoided the thermal degradation or solvent contamination of samples.