Impact of fining agents on the volatile composition of sparkling mead

Sparkling mead is obtained by secondary fermentation of the mead involving the addition of starter yeast culture, sucrose, nutrients and fining agents. The aim of this study was to evaluate the effect of different fining agents (tannins vs combined fining agents) on the volatile composition of sparkling mead. Sparkling mead was produced from a base mead using a commercial yeast strain (Saccharomyces bayanus) and the volatile compounds were determined by gas chromatography–flame ionisation detection and gas chromatography–mass spectrometry. Thirty six volatile compounds were quantified and the major groups were alcohols (73.2%), acetates (19.1%), carbonyl compounds (5.5%) and ethyl esters (1.2%), represented by 3‐methyl‐1‐butanol, ethyl acetate, acetaldehyde and monoethyl succinate, respectively. The remaining compounds were present at <1%. Eleven volatile compounds exhibited odour activity values >1, with ethyl octanoate and ethyl hexanoate contributing to the aroma of sparkling mead, with fruity, strawberry and sweet notes. The combined fining agents caused a marked decrease in the concentration of volatile compounds compared with tannins. In general, 3‐ethoxy‐1‐propanol, ethyl lactate, ethyl octanoate, diethyl succinate, diethyl malate, monoethyl succinate, 2‐methylpropanoic acid, hexanoic acid, octanoic acid, acetaldehyde, acetoin, furfural, benzaldehyde, 5‐hydroxymethylfurfural, trans‐furan linalool oxide, cis‐furan linalool oxide and 4‐oxo‐isophorone decreased in concentration. Conversely, 1‐propanol and 2‐methylpropanoic acid (tannins) and ethyl butyrate (combined fining agents) increased in concentration. The remaining volatile compounds were not affected. Significant differences (p < 0.05) were found for 19 volatile compounds independently of the type of fining agents used. © 2018 The Institute of Brewing & Distilling     

Evaluating potential alternatives to potassium caseinate for white wine fining: Effects on physicochemical and sensory characteristics

The use of potassium caseinate for wine fining can cause allergic reactions and must be included on wine bottle labels. The focus of this research was to determine if non-allergenic pea protein or polyvinylpolypyrrolidone (PVPP) are possible alternatives for wine fining. Trials were performed to compare the effects of these potential fining agents on phenolic compounds, browning potential, turbidity and sensory attributes. The results indicate that flavonoid and non-flavonoid phenols decreased (p < 0.05) in the wines treated with potassium caseinate, pea protein, and PVPP. All fining agents decreased (p < 0.05) wine colour. Potassium caseinate was the most effective fining agent for reducing browning potential. Pea protein and potassium caseinate resulted in increased clarity of the final wines. No sensorial differences (p < 0.05) were detected among the wines prepared with the different fining agents. This study provides information that could be used to select an appropriate alternative to potassium caseinate.     

Exploring stingless bee honey from selected regions of Peninsular Malaysia through gas chromatography–mass spectrometry–based untargeted metabolomics

Volatile organic compounds in honey are known for their considerable impact on the organoleptic properties of honey, such as aroma, flavor, taste, and texture. The type and composition of volatile organic compounds are influenced by entomological, geographical, and botanical origins; thus, these compounds have the potential to be chemical markers. Sixty-two volatile compounds were identified using gas chromatography–mass spectrometry from 30 Heterotrigona itama (H. itama) honey samples from 3 different geographical origins. Hydrocarbons and benzene derivatives were the dominant classes of volatile organic compounds in the samples. Both clustering and discriminant analyses demonstrated a clear separation between samples from distant origins (Kedah and Perak), and the volcano plot supported it. The reliability and predictability of the partial least squares–discriminant analysis model from the discriminant analysis were validated using cross-validation (R²: 0.93; Q²: 0.83; accuracy: 0.97) and the permutation test (p < 0.001), and the output depicted that the model is legitimate. In combination with the variable importance of projection (VIP > 1.0) and the Kruskal–Wallis test (p < 0.01), 19 volatile organic compounds (encompassed aldehydes, benzene derivatives, esters, hydrocarbons, and terpenoids) were sorted and named potent chemical markers in classifying honey samples from three geographical origins. In brief, this study illustrated that volatile organic compounds of stingless honey originated from the same bee species, but different geographical origins could be applied as chemical markers.     

不同下胶剂对蓝莓红酒下胶效果的研究

选用豌豆蛋白(INOFINEV)、颗粒皂土(BOG)、复合抗氧化澄清剂(FPR)3种下胶剂对蓝莓酒进行下胶,通过蓝莓酒沉淀物、浊度和色度确定最佳的下胶效果.研究结果表明,单一下胶实验中,BOG是适宜的下胶剂,蓝莓酒形成的沉淀物最多,紧实度最好;最佳用量为0.6 g/L,蓝莓酒浊度1.7 NTU,色度值降低9.49％.复...     

Effects of fining agents on trans-resveratrol concentration in wine

Resveratrol has been identified as a wine component related to moderate wine consumption and a reduction in serum cholesterol levels. Processes such as wine fining that result in loss of resveratrol during winemaking are therefore of interest, and led to these present studies. A number of agents were compared and were found to lower resveratrol levels in all wines to some extent. Results from two studies (1996 and 1997) are reported. The standard addition method was used in combination with High Pressure Liquid Chromatography to calculate resveratrol levels. In Study 1 (1996), recommended maximum levels of all fining agents (Level 3), bentonite, egg white, gelatin + kieselsol and polyvinylpolypyrrolidone (PVPP), lowered resveratrol levels significantly compared to controls (Level 0). Nevertheless, addition of fining agents at Level 0 resulted in resveratrol levels that were significantly higher than those at Level 3, but resveratrol levels in wine from Level 0 were not significantly different from Level 1. In Study 2 (1997), carbon + egg white, and gelatin + kieselsol fining was studied, and their effects differed according to grape variety. Least removal of resveratrol by carbon fining occurred in wine from Cabernet Sauvignon (Vitis vinifera) whereas most removal occurred in wines from Cynthiana (Vitis aestivalis) and Noble (Vitis rotundifolia). Resveratrol levels of control wine were significantly higher than resveratrol levels of wine treated with recommended maximum addition of fining agent in all varieties. Taken overall, any addition of any fining agent lowered resveratrol levels in all wines to some extent, but complex interactions between fining agent and wine variety resulted in different regression trends. While recognising the constraints set by our particular data that could reflect unique circumstances, we are nevertheless able to infer from these trends that low levels of fining agents can be used without statistically significant loss of resveratrol.     

High-cell-density fermentation of Saccharomyces cerevisiae for the optimisation of mead production

Mead is a traditional drink that contains 8%–18% (v/v) of ethanol, resulting from the alcoholic fermentation of diluted honey by yeasts. Mead fermentation is a time-consuming process and the quality of the final product is highly variable. Therefore, the present investigation had two main objectives: first, to determine the adequate inoculum size of two commercial wine-making strains of Saccharomyces cerevisiae for the optimisation of mead fermentation; and second, to determine if an increase in yeast pitching rates in batch fermentations altered the resulting aroma profiles. Minor differences were detected in the growth kinetics between the two strains at the lowest pitching rate. With increasing pitching rates net growth of the strain ICV D47 progressively decreased, whereas for the QA23 the increasing inoculum size had no influence on its net growth. The time required to reach the same stage of fermentation ranged from 24 to 96 h depending on the inoculum size. The final aroma composition was dependent on the yeast strain and inoculum size. Fourteen of the twenty-seven volatile compounds quantified could contribute to mead aroma and flavour because their concentrations rose above their respective thresholds. The formation of these compounds was particularly pronounced at low pitching rates, except in mead fermented by strain ICV D47, at 10⁶ CFUs/mL. The esters isoamyl acetate, ethyl octanoate and ethyl hexanoate were the major powerful odourants found in the meads. The results obtained in this study demonstrate that yeast strain and inoculum size can favourably impact mead's flavour and aroma profiles.     

Mineral composition,antioxidant and cytotoxic biopotentials of wild‐growing Ganoderma species (Serbia): G. lucidum (Curtis) P. Karst vs. G. applanatum (Pers.) Pat.

The aim of this work was to analyse mineral composition and chemical profile of two nonedible fungal species: Ganoderma lucidum and Ganoderma applanatum (Fru?ka Gora, Serbia) vs. their antioxidant (ABTS and A.E.A.C. assay) and cytotoxic biopotentials (MTT assay on MCF‐7). Both species were analysed for their content of macro‐ and microelements by atomic absorption spectrophotometry, while phenolic profile of EtOH and H₂O extracts was examined by LC‐MS/MS technique. Both species mostly contained the following ions: K⁺ > Ca²⁺ > Mg²⁺ > Mn²⁺ > Zn²⁺ > Cu²⁺ > Cr³⁺. Among nine phenolic compounds, the highest content of vanillic acid was detected in G. applanatum extracts while protocatechuic acid in EtOH extract and quinic acid in H₂O extract were mostly contained in G. lucidum. Ganoderma applanatum EtOH extract showed the best antioxidant activities related to its phenolic and flavonoid content. Further, the best cytotoxic effect after 72 h was observed in this extract as well.     

Analysis of volatile compounds in L. edodes blanched by hot water and microwave

The comprehensive flavour characterisation and volatile compounds of raw L. edodes, hot water blanching (HB) sample and microwave blanching (MB) sample were comparatively analysed by electronic nose technology and headspace solid‐phase micro‐extraction combined with gas chromatography‐mass spectrometry (HS‐SPME‐GC‐MS). Results indicated that volatile components in L. edodes markedly changed after HB and MB. Volatile compounds of raw L. edodes consisted mainly ketones, sulphide and alcohols, and 3‐octanone, as well as 1‐octen‐3‐one, were the major compounds. The content of ketones and sulphides in blanched samples markedly decreased, while the relative content of aldehydes, hydrocarbons and esters increased, which became the major volatile compounds of treatment samples. In addition, the percentage contents of esters, alcohols and sulphides in MB samples were significantly (P < 0.05) higher than that in HB samples, especially 1‐octen‐3‐ol, which contributes more to mushroom flavour. Therefore, MB is a better pretreatment method of L. edodes processing and cooking according to the results of experiment.     

Repercussion of the clarification treatment agents before the alcoholic fermentation on volatile composition of white wines

Albariño must was clarified with two fining agents, as bentonite and silica gel. Alcoholic fermentation was carried out at semi-industrial scale, and the concentration of free monoterpenes, norisoprenoids, C₆-alcohols, higher alcohols, fatty acids, ethyl esters, and acetates was then investigated. The use of bentonite allows loss of several volatile compounds compared to wine control. In a second step, the effect of clarification–stabilization treatments with silica gel on aromatic substances was compared in order to study this influence in white wines elaborated from different aromatic varieties (Albariño and Loureira). The results showed that the use of these fining agent plays a significant role in the wine volatile composition.     

Changes in flavour compound profiles of precooked pork after reheating (warmed-over flavour) using gas chromatography–olfactometry–mass spectrometry with chromatographic feature extraction

The unclear components and complex evaluation indicators affect the effectiveness of inhibition methods for warmed-over flavour (WOF). To evaluate the main components of WOF, the changes in flavour compound profiles of precooked pork after reheating were investigated quantitatively by using gas chromatography–olfactometry–mass spectrometry with chromatographic feature extraction. A total of 49 volatile compounds were identified, including 22 aroma-active compounds that were primarily derived from lipid oxidation. Fifteen key volatile compounds were obtained that represented principal components of the changes in flavour compound profiles, of which 1-octen-3-ol, (Z)-2-octenal and (E,E)-2,4-decadienal made the greatest contribution to the principal components and achieved odour activity value (OAVs) >1.0 after reheating. The results showed that the three compounds are the dominant volatile compounds and potential evaluation indicators of WOF. This study provides a further understanding of the components of WOF in precooked pork and an effective analysis method of gas chromatography.     

Effect of bioaugmentation on biochemical characterisation and microbial communities in Daqu using Bacillus,Saccharomycopsis and Absidia

Daqu, a saccharifying and fermenting agent for the production of Chinese vinegar and liquor, is manufactured through a spontaneous solid-state fermentation process (SSF). To investigate the influence of bioaugmentation with native microorganisms on Daqu SSF process, physicochemical properties, microbial biomass, volatile compounds and microbial communities were analysed in laboratory-scale Daqu. The results showed that the amylase activity of Daqu enhanced 6.35% ± 0.74% by inoculating Bacillus amyloliquefaciens, Saccharomycopsis fibuligera and Absidia corymbifera. Obviously higher microbial richness was found in the Daqu with bioaugmentation, although the microbial community structure remained relatively stable. Moreover, a total of twenty-two volatile compounds were detected in the mature Daqu. Slightly increase in the content of alcohols was found in the enhanced group by fungal inoculation, including ethanol (46.58 ± 1.36 mg kg⁻¹), isobutanol (0.19 ± 0.04 mg kg⁻¹) and isoamyl alcohol (1.55 ± 0.13 mg kg⁻¹). This study demonstrated that bioaugmentation had a positive effect on the amylase activity, main volatile compounds and microbial community richness.     

Foam aptitude of Bobal variety in white sparkling wine elaboration and study of volatile compounds

Fining agents can also have an effect on the flavor components of the must, and other compounds which are important for the sensory characteristics and in the case of sparkling wine, the foam quality. The influence of fining agents and tirage solution, on volatile compounds, and foam characteristics of sparkling wines made from grapes of the Bobal variety was studied. The data obtained show how the fining agent affects the foam properties and the final volatile composition of sparkling wines. In this study, it was bentonite with gelatine that produced amounts of acetates and esters. The use of Colle 2P in the tirage solution means that more aromatic sparkling wines with better foam characteristics can be obtained.     

Effect of sulphur dioxide concentration added at different processing stages on volatile composition of ciders

This study evaluated the effect of sulphur dioxide (SO₂) added at different steps in the process on the volatile composition contributing to the fruity aroma of cider. Potassium metabisulphite was added (150 and 300 mg/L) at three processing steps (a) crushed apple, (b) apple must and (c) final product. The SO₂ added to the crushed apple either maintained or increased the fermentation rate, whereas the addition to the apple must slowed the fermentation rate. The addition of 300 mg/L of potassium metabisulphite to Golden Delicious apple must inhibited fermentation. The losses of volatile compounds varied from 23 to 46% and from 33 to 97% in all of the treatments with 150 and 300 mg/L of potassium metabisulphite, respectively. 3‐Methyl‐1‐butanol, acetaldehyde and ethyl ethanoate corresponded to >85% of the volatile compounds in the cider; 3‐methyl‐1‐butanol was not affected by the sulphur dioxide. Acetaldehyde showed the greatest reduction (>80%) with the addition of sulphur dioxide and ethyl ethanoate was reduced when the compound was added to the crushed apple and apple must. All of the interactions between the apple variety, the stage of SO₂ addition and the concentration of SO₂ showed significant negative impact on volatile compounds. © 2018 The Institute of Brewing & Distilling     

Rapid determination of volatile composition from Polygala furcata Royle by MAE–HS-SPME followed by GC–MS

Based on microwave-assisted extraction (MAE) and headspace solid-phase microextraction (HS-SPME) followed by gas chromatography mass spectrometry (GC–MS) was developed for the fast determination of volatile chemical compositions of Polygala furcata Royle, the experimental parameters of the MAE–HS-SPME were optimized by orthogonal experimental design. The results indicated that the optimum condition of the determination of the volatile compounds in P. furcata Royle. was achieved with the experimental parameters including microwave power of 400 W and irradiation time of 4 min, sample size 2.0 g. Under the optimal conditions, for the first time, 52 volatile compounds were separated and identified from the fresh plants of P. furcata Royle. The highest content component of the 52 compounds was 2-hydroxybenzoic acid methyl ester (21.65%). The relative standard deviation values <7% showed that the method of MAE–HS-SPME followed by GC–MS has good precision. The experimental results demonstrated that it is a simple, time-saving and solvent-free method, and it is a potential analytic tool for the determination of the volatile compounds of the vegetations materials and other materials.     

Manipulation of volatile compound transformation in durian wine by nitrogen supplementation

This study evaluated the impact of added diammonium phosphate (DAP) and a L‐leucine‐L‐phenylalanine mixture (Leu+Phe) on durian wine fermentation by Saccharomyces cerevisiae var. bayanus EC‐1118. Changes in yeast cell population, ^oBrix, sugars, organic acids and pH were similar in all fermentations, regardless of nitrogen supplementation at a concentration of 150 mg N L^?1. The supplementation of Leu+Phe accelerated the utilisation and reduced the formation of volatile sulphur compounds such as diethyl disulphide, ethyl thioacetate and 2‐(ethylthio)ethanol, which were 64.3%, 26.0% and 48.4% lower than the control, respectively. Nevertheless, the supplementation of Leu+Phe heightened the production of isoamyl alcohol, 2‐phenylethyl alcohol and their corresponding esters, especially isoamyl acetate was 1.6 times and 2‐phenylethyl acetate was 26.5 times higher than the control. The supplementation with DAP exerted negligible effects on the volatile composition. The results of this study suggest that the addition of specific amino acids may be a novel approach to manipulating durian wine flavour by suppressing or accentuating the formation of certain aroma compounds.     

Fining white wine with plant proteins: effects of fining on proanthocyanidins and aroma components

Plant-derived insoluble proteins (wheat gluten, and isolates from pea, lentil, and soybean) were used as fining agents in model white wine (made from Catalanesca grapes) after cold stabilization. Plant proteins were effective in giving a fast and remarkable decrease in turbidity. GC/MS and HPLC/MS approaches indicated that individual proteins had a different impact on the levels of compounds relevant to wine stability. Protein stability of wine was not affected by fining with plant proteins. Lentil proteins and gluten gave the best removal of monomeric and dimeric flavonol. Both caused a decrease in the total content of fermentative aroma compounds, such as ethyl esters, acetate esters, and alcohols. Lentil proteins had the highest impact on the aroma components, giving a marked decrease in aroma components. Gluten may thus be regarded as giving the best balance between fining efficacy and retention of aroma compounds. Also, gluten in the treated wines remained well below the suggested threshold for gluten-free foods. This study provides a methodological frame for thorough characterization of the impact of specific interventions on key wine components.     

Characterization of the aroma compounds in crystal malt

Crystal malt, the most popular type of specialty malt used in beer brewing, plays a vital role in forming complex flavor and color. Nevertheless, crystal malt is only defined based on the malting process, and there is not any standard to evaluate its quality. In the current study, the volatile aroma constituents of commercial crystal malt samples were analyzed with headspace solid-phase microextraction combined with gas chromatography–mass spectrometry, in order to explore the characteristic aroma compounds of crystal malt. The average concentration of volatile aroma compounds in 10 crystal malt samples is 587 µg L⁻¹, ranging from 347 to 1265 µg L⁻¹. A total of 38 aroma compounds were identified, 47% of which were existed in all the 10 samples. Based on principal component analysis and odor activity value, isobutyraldehyde, 2-methylbutanal, furfural, 2-acetyl-1H-pyrrole, oct-1-en-3-ol, 4-methyl-2-phenyl-2-pentenal, and (2E)-2-isopropyl-5-methyl-2-hexenal could be considered the characteristic aroma compounds of crystal malt. The results of this present study would help to establish a standard to assess the quality traits of crystal malt sample.     

Quality of base and sparkling wines as influenced by the type of fining agent added pre-fermentation

A comparison of the effect on base wines of pre-fermentative clarification between a fining mixture (potassium caseinate, bentonite and cellulose microcrystalline) and bentonite was carried out. Fining agents were added to two grape juices from different cultivars: Macabeo and Parellada. These varietal wines are used for making sparkling wine within the appellation (certified brand of origin) Cava. Vinification was done in parallel on an industrial scale (100 000 l). The use of the fining mixture in grape juice made the fermentations more complete and gave wines with less browning ability, more foam stability time and a lower content of nitrogenous fraction, polyphenols and some volatile compounds than the wines treated with single bentonite. Sensorial analysis showed that the wines produced with the use of different fining agents had different organoleptic characteristics. In addition, the effect of fining agent added pre-fermentatively was observed on some components of sparkling wines.     

Influence of processing steps and fruit maturity on volatile concentrations in juices from clementine, mandarin, and their hybrids

During growth, ripening, and post-harvest, the quality of fruits can be modified by various stresses. Ample maturation allows prolonged storage and increases the quality of citrus fruits. The eight major volatile compounds in fresh juices from mandarin (Citrus reticulata Blanco var. Willow Leaf), clementine (Citrus reticulata × Citrus sinensis var. Commune), and their six cross-pollinated hybrids were quantified by gas chromatography. Mandarin juice contained the highest volatile concentration (2177.6 ± 110.6 mg L⁻¹), whereas the total aromatic compounds of the hybrid and clementine juices were lower (1060.6 ± 81.6–1724.2 ± 138.5 mg L⁻¹ and 864.8 ± 67.8 mg L⁻¹, respectively). Limonene was the major compound (667.3 ± 53.7–1259.9 ± 98.4 mg L⁻¹) in all juices. We observed significant differences according to the process of juice extraction used (with and without peel). The relative volatile concentration was higher when the juice was extracted with peel, and the juicing process induced differences in the relative volatile concentrations of between 20 and 40%. The levels of volatile compounds in the juice changed according to the degree of fruit maturity. The concentrations of the eight major juice components increased during ripening and until the commercial maturity stage when the juice was obtained from peeled fruits, whereas their concentrations increased until the post-maturation stage when the juices were produced from whole fruits. These two factors determined the contributions of these compounds to the characteristic aromas of Citrus juices.     

Volatile composition of wines from cvs. Blanco lexítimo,Agudelo and Serradelo (Vitis vinifera) grown in Betanzos (NW Spain)

Wine aroma is formed by volatile compounds of different chemical natures and origins. Betanzos is the most northern viticole geographic area from Galicia (NW Spain). The aromatic profiles of wines produced from two white varieties (Blanco lexítimo and Agudelo) and one red variety (Serradelo) from Betanzos, harvested in 2006 and 2007, have been established by gas chromatography (GC/FID). A total of 35 varietal and fermentative aroma compounds were identified and quantified in free volatile form, which include terpenols, C₁₃‐norisoprenoids, alcohols, esters, volatile fatty acids and volatile phenols. To ascertain the compounds with major impact odours, the Odour Activity Value (OAV) was calculated. Twelve compounds showed concentrations above their perception threshold (OAV>1). The results obtained suggest that ethyl octanoate (apple), isoamyl acetate (banana), ethyl hexanoate (fruity) and β‐damascenone (floral) were the most powerful odorants for the white wines Blanco lexítimo and Agudelo from Betanzos. Ethyl octanoate and β‐damascenone (fruity and floral aroma respectively) were the most odorant for the red wine Serradelo.