echemi logo
Product
  • Product
  • Supplier
  • Inquiry
    Home > Biochemistry News > Microbiology News > The effect of low temperature fermentation on the type and content of wine aroma composition.

    The effect of low temperature fermentation on the type and content of wine aroma composition.

    • Last Update: 2020-07-29
    • Source: Internet
    • Author: User
    Search more information of high quality chemicals, good prices and reliable suppliers, visit www.echemi.com
    Proper cryogenic stress causes the metabolism of yeast to be regulated by different mechanisms and react accordingly, producing different content of metabolites, which in turn affects the quality of wine

    Low-temperature fermentation is conducive to improving the aroma and sensory properties of wine, mainly due to the increase of acetate and ethyl esters, and the reduction of advanced alcohol and volatile acid content

    From the angle of wine aroma composition, related metabolism and gene expression, this paper analyzes the effect of low temperature on wine quality, and combines non-wine yeast suitable for low temperature fermentation, which provides a theoretical basis for low temperature fermented wine



    aroma is one of the important characteristics of judging the quality of wine

    The aroma of wine can be divided into three categories: variety aroma or primary aroma, determined by grape variety, fermented aroma or secondary aroma, produced by yeast and bacteria during the fermentation of alcohol and lactic acid, aging aroma or three-level aroma, derived from the transition between aromas during the aging process

    Hundreds of compounds produced by the metabolism of microorganisms (mainly yeasts) in the process of alcohol fermentation play a leading role in the aroma composition of wine



    the chemical composition and fermentation conditions of grape juice are the two most important factors affecting yeast metabolism

    It is generally believed that low temperature spent on wine fermentation can increase and retain more volatile aroma scents, and a simple explanation may be that low-temperature fermentation retains higher primary and secondary flavor substances than normal temperature fermentation

    As a result, the improvement in the aroma and taste of low-temperature fermented wines can be attributed to more retention of steroids, increased production of volatile esters and C6-C10 medium-chain fatty acidests, and lower levels of advanced alcohols and volatile acids

    However, temperature also affects the growth rate and fermentation rate of yeast, the lower the temperature, the longer the fermentation time

    Changes in fermentation rates can also alter the ecology of yeast and bacteria, ethanol sensitivity and yeast metabolism

    Although fermentation temperature significantly affects the growth rate of yeast and its central metabolism, the effect of fermentation temperature on the biosynthesis pathway of yeast fragrance compounds is still unclear



    low-temperature fermentation of wine increases the probability of slow or stagnant fermentation, which can be reduced by selecting wine yeasts suitable for low-temperature fermentation while maintaining good wine quality

    Some non-brewery yeasts (Non-Saccharomyces, NSC) are better able to adapt to low temperatures than saccharomyces cerevisiae

    The secondary metabolites produced by NSC in the wine fermentation process play an important role in the formation of wine flavor substances, especially the early fermentation of NSC metabolism will produce esters, advanced alcohols, glycerin, aldehydes and succinic acid and other important components that affect the sensory characteristics of wine make wine have a more complex taste and aroma



    This paper summarizes the effects of low temperature on the type and content of wine aroma composition, the metabolic pathways of low temperature on aroma composition, the effect of key enzymes and their gene expression, and the non-wine yeast suitable for low temperature fermentation, which aims to provide a theoretical basis for better studying the fermentation mechanism at low temperature and improving the quality of wine



    1 Low temperature seisquil effects on wine aroma composition



    volatile compounds synthesized from wine yeast include premium alcohols (heterool, almonds and flowers), medium chain and long chain volatile acids (fat, cheese and sweat), acetate and ethyl esters (fruit and flower), aldehydes (aromas of creams, fruits and nuts), and more



    1.1 alcohols



    advanced alcohols can be synthesized by anabolic by the sugar metabolism intermediate, or by the multi-step metabolic reaction - the Ehrlich pathway, by the branch chain amino acids

    Propylene alcohol and isobutanol at a very low concentration of 0 -5 degrees C, the highest detection of the mass concentration of 48 mg/L; Low temperatures often lead to lower concentrations of advanced alcohols, which are thought to have a positive impact on product quality



    1.2 esters



    low-temperature fermented wines, yeast produces an increase in floral aromas (fatty acid ethyls) and fruit (acetate) and maintains a high level of variety aroma (ferns)

    This is due to increased stability of volatile compounds, reduced evaporation loss, and metabolic differences in yeast, i.e

    changes in fatty acid synthesis to alter the composition of cell membranes

    Acetate is made of advanced alcohol and acetyl coenzyme A

    This reaction is catalyzed by acetylmetase encoded by the genes ATF1 and ATF2, and the Esterases encoded by IAH1 and TIP1 also have an important effect on the final concentration of acetate in wine

    Ethyl esters, such as ethyl acetate, buterate, ethyl hexate, ethyl acetate, ethyl acetate and ethyl lactate, give the wine the ideal fruit and flower aroma

    They are produced by the combination of ethanol and acetylase A, which are catalyzed by an acetyyl transferase, which is encoded by the genes EHT1, EEB1, and YMR210W

    The final concentration of ethyl esters in the same wine is also closely related to esterases encoded by IAH1 and TIP1

    The largest difference between the



    15 degrees C and 28 degrees C is the yield of ethyl esters, which is very high at 15 degrees C, which is consistent with other studies of wine volatile compounds

    The concentrations of 4 volatile compounds with positive sensory effects were significantly higher at 28 degrees C than 15 degrees C, namely, acetate-2-methylbutyleste, 2-methyl butylet (the fruit of bananas and pineapples), 2-phenethanol and 2-phenyl ethanol acetate (flower scent)

    THE RESULTS OF THE EXPERIMENTS OF GAMERO ET AL

    HAVE SHOWN THAT THE YIELD OF ACETATE INCREASES AT 28 DEGREES C, EVEN IF THE CORRESPONDING ALCOHOL YIELD IS HIGH AT 12 DEGREES C, WHICH MAY INDICATE AN INCREASE IN THE ACTIVITY OF ACETYL TRANSFERASE (ATF) AT HIGHER TEMPERATURES

    In addition to ethyl acetate, fermentation at low temperatures is significantly more conducive to the production of ethyl esters



    1.3 acids



    volatile fatty acids also contribute to the aroma of wine

    Fatty acids are important components of cell membranes and precursors of more complex molecules, such as phospholipids

    They are re-condensed by acetyl coenzyme A and catalyzed by fatty acid synthase complex



    levels of malic acid, ethanol, and some advanced alcohols (isobutanol and isoprene) increase with temperature

    The concentration of acetic acid is reduced at low temperatures

    The concentration of succinic acid is also high at 21 degrees Celsius

    When the main component analysis of organic acids was carried out, no significant grouping was observed; Temperature has a greater effect on naturally fermented wines, which may be due to the interaction between temperature and other factors, such as the natural presence of yeast populations on the grape skin

    Fermentation is suitable for 18 degrees C, as the content of advanced alcohols and organic acids is appropriate

    Regardless of the yeast used, a temperature slightly below 20 degrees C is the most suitable temperature for wine fermentation

    One strategy



    yeast cells to adapt to low-temperature conditions is to increase the percentage of medium-chain fatty acids (MCFA)

    If the increase in MCFA is the most significant change in the strain of low-temperature growth, then the presence of citric acid (C8) is the most important characteristic of cold-resistant yeast Saccharomyces kudriavzevii compared to S

    cerevisiae



    cytoplasmic membrane fatty acid analysis showed that dry yeast had similar levels of unsaturation, between 70% and 80%, no medium chain fatty acids (MCFA), and long-chain saturated fatty acids (SFA) were the most frequent membrane fatty acids in the entire fermentation

    Lipid composition varies with the temperature of growth

    The S.cerevisiae strain regulates optimal membrane fluidity at low temperatures through changes in fatty acid unsaturation

    However, no change in the percentage of unsaturated fatty acids (UFA) at different growth temperatures was observed, but the concentration of MCFA was higher at low temperatures



    1.4 Other aroma components



    in general, the reduction of acetaldehyde and acetic acid is one of the main advantages of low temperature fermentation

    The content of acetaldehyde and acetic acid produced by pre-adaptation vaccination was lower than that of a fermentation initiation agent only



    in some "simple" or "non-aromatic" grape varieties, such as the sashimi grapes, in the process of alcohol fermentation synthesis of characteristic varieties of aromas, proved to be volatile thiol

    Three major volatile aromatic thiols - 4-pyridine-4-methyl isopyl butylketone (4MMP), 3-pyridine-1-hexanol (3MH) and 3-pyrithyl hexyl ester (3MHA) - were identified as the characteristics of the "yellow poplar", "grapefruit" and "thyscoopyfruit" that make up this wine

    These compounds are also found in wines made by Joan, Riesling, Pigeon Cage White, Little Manson, Cabernet Sauvignon and Merlot Grapes

    Two sulfur compounds (4MMP and 3MH) are present in grape juice in the non-volatile form of sulfur-cysteine conjugate

    Volatile thiol is released by yeast from the corresponding sulfur-cysteine conjugate during alcohol fermentation

    Recent studies using genetic screening techniques identified four genes of the experimental strain that affect the release of volatile thiol 4MMP

    However, the mechanism by which yeast cysteine-related precursors are converted into aromas is not clear



    the final concentration of 4MMP and 3MH in the wine is higher than 13 degrees C when the alcohol is fermented at 20 degrees C

    Prior to HOWELL et al

    in synthetic medium, the effects of fermentation temperature (18 and 28 degrees C) on the release of 4MMP of different yeast strains were studied, and found that high temperatures (28 degrees C) had a positive effect on the 4MMP levels of 2 yeasts

    These comparisons of fermentation temperatures of 28 degrees C and 18 degrees C are consistent with those of 20 degrees C and 13 degrees C



    in maSNEUF and other studies, the concentration of 3MHA was higher in high-temperature fermentation samples

    The level of 3MHA is also closely related to the number of 3MH

    Therefore, for 3MHA, the temperature does not appear to affect yeast metabolism, but indirectly affects the level of 3MHA through the concentration of 3MH



    2 the effects of low temperatures on yeast metabolism and related gene expression



    EUGENIA, etc., analyzed proteomics associated with saccharomyces bayanus var.uvarum winemaking properties

    The protein classification of molecular functions shows that there are 24 different categories at 13 degrees C, 8 of which are unique to 13 degrees C, and 16 different categories are identified at 25 degrees C, but none of them are unique

    These unique groups of 13 degrees C are (1) antioxidant activity; (2) amino acid binding; (3) heteroenzyme activity; (4) heteroenzyme activity; (5) protein markers; (6) peptide binding; (7) ribbrion complex binding; (8) metal cluster binding; 10% of the total

    Of particular interest is the antioxidant active group, which removes free radicals from cells to reduce molecular damage

    As mentioned earlier, wine is a mixture of natural compounds such as flavonoids and polyphenols, which have important antioxidant activity

    Their data support the hypothesis that the enzyme system that produces these compounds is raised during low-temperature fermentation



    the classification of the genetic ontological body of biological processes found 70 categories: 27 are unique to 13 degrees C and 17 are unique to 25 degrees C

    The number of categories described is high, indicating changes in the activity of different proteins during wine fermentation

    By further examining the categories at 13 degrees C, there are many metabolic processes involving wine aromas, such as (1) cell aldehyde metabolism processes; Most unique categories constitute the main way to contribute to the accumulation of metabolites such as wine aromas, which are directly related to the quality of the wine



    the specific categories described are: (1) fermentation; (2) cell growth; (3) polysaccharide metabolism process, (4) energy reserve/metabolic process, and (5) ethanol metabolism process, all of which involve different steps in the fermentation process, from cell growth to ethanol synthesis



    cold-resistant yeast S.bayanus var.uvarum in 13 degrees C expression of the increased protein is acetone acid de-serotonin, glycerin-1-phosphate hydrolytic enzyme 2, acetaldehyde dehydrogenase (Ald6p, Ald3p), thiamine synthase (Thi13p), oxyoxymethyl transferase and methonenine synth metabolism, including aromatic compounds

    These enzyme activities promote the anabolic metabolism of glycerin, isofrol and 2-phenyl ethanol acetate, consistent with the unique sensory characteristics of S.bayanus var uvarum in wines fermented at 13 degrees C



    2.1 sugar metabolism



    the main sugars in grape juice, glucose and fructose fermented into ethanol and CO2 to provide energy and carbon compounds for yeast growth

    The winemaking process is mainly the conversion of sugars from grape juice into ethanol

    The sugar metabolism of yeast is the main metabolic process that determines the final ethanol content and, to a large extent, determines the sensory characteristics of wine

    In the process of yeast ethanol fermentation, due to the simultaneous presence of fermentation and other metabolic activities, yeast in addition to fermenting 92% - 95% of the sugar in grape juice into ethanol, CO2 and heat, yeast can also use another 5%-8% of the sugar to produce a series of other compounds, namely ethanol fermentation by-products

    The most important by-products are glycerin and acetic acid, followed by esters-based aromas



    glycerin is one of the main metabolites produced in the fermentation process of wine, which brings sweet, soft and plump taste to the quality of wine and reduces the astringent taste of the wine

    Glycerin is involved in the osmotic regulation of yeast and the adaptation to low temperature growth

    The production of glycerin balances the ratio of NADH/NAD in the cell, and glycerin, like algal sugar, acts as an antifreeze

    The synthesis of S.cerevisiae glycerin is produced by catalyzing the reduction of dihydroxypropylene phosphate (DHAP) by 3-phosphate glysphosphatase (GPP gene coding) by NAD-dependent 3-phosphate glycediadase (GPD gene coding), and then by catalytic 3-phosphate dephosphate

    Experiments have shown that the synthesis of glycerin in low-temperature-induced cells is activated immediately, and that the yield is higher than that of 12 degrees C

    This article is an English version of an article which is originally in the Chinese language on echemi.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to service@echemi.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

    Contact Us

    The source of this page with content of products and services is from Internet, which doesn't represent Echemi's opinion. If you have any queries, please write to service@echemi.com. It will be replied within 5 days.

    Moreover, if you find any instances of plagiarism from the page, please send email to service@echemi.com with relevant evidence.