Vinegar aging method

Abstract

The invention discloses an ageing method of table vinegar, which comprises the following steps: carrying out gradient constant-temperature and temperature-control ageing on vinegar grains which are fermented for the last day. In a vinegar aging process, differences of environmental factors, seasons and brewing processes can influence dynamic succession of microbial communities of vinegar culture, so that the aging process is unstable. According to the research, the quality of the vinegar grains can be effectively improved by manually intervening the aging temperature and time, and by adopting gradient temperature-control constant-temperature aging, flavor substances in the vinegar grains can be increased, and the content of nutrient substances can also be increased.

Description

Technical Field

[0001] The invention belongs to the technical field of vinegar aging, and more particularly relates to a vinegar aging method. Background Art

[0002] At present, the aging of vinegar mainly adopts the natural aging method, which is greatly affected by temperature and seasonal changes, resulting in unstable quality of aged vinegar mash. At the same time, aging takes a long time. Without human intervention, long-term uncontrolled aging is more likely to cause food safety problems. Summary of the Invention

[0003] Based on the above problems, the present invention provides a method for aging vinegar, in order to solve the related problems in the background technology.

[0004] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0005] A method for aging vinegar comprises the following steps:

[0006] The vinegar mash on the last day of fermentation will be aged under gradient constant temperature control.

[0007] In some embodiments, the gradient constant temperature controlled aging comprises:

[0008] The first stage of aging is carried out at 28-32℃ for 28-33 days;

[0009] The wine then undergoes a second aging phase at 42-48°C for 28-33 days.

[0010] In some embodiments, the gradient constant temperature controlled aging comprises:

[0011] The first stage of aging was carried out at 30°C for 30 days;

[0012] Then a second stage of aging was carried out at 45°C for 30 days.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] During vinegar aging, environmental factors, seasonal variations, and brewing techniques can influence the dynamic succession of the vinegar mash's microbial community, leading to instability during the aging process. Our research has shown that manipulating the aging temperature and time can effectively improve the quality of the mash. Using gradient temperature control and constant temperature aging can not only enhance the flavor compounds in the mash, but also increase the nutrient content. DETAILED DESCRIPTION

[0015] The present invention will be further described below with reference to the embodiments. The embodiments described are only a part of the embodiments of the present invention and are not all embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without making creative work are all within the scope of protection of the present invention.

[0016] Example 1

[0017] A method for aging vinegar comprises the following steps:

[0018] The vinegar mash on the last day of fermentation was subjected to gradient temperature control and constant temperature aging. After aging at 30°C for 30 days, the total acid reached 0.78 mmoL / g, the Maillard reaction products accumulated, and the lactic acid content increased from 23.01 mg / kg to 33.66 mg / g, an increase of 33%.

[0019] The total amino acid content increased from 17.21 g / kg to 19.91 g / kg, an increase of 37.45%, among which arginine (Arg) increased by 29%, serine (Ser) increased by 22%, threonine (Thr) increased by 13%, tyrosine (Tyr) increased by 41%, proline (Pro) increased by 32%, methionine (Met) increased by 21%, and phenylalanine (Phe) increased by 23%.

[0020] The content of various volatile flavor substances increased, with esters and phenols showing a significant increase. Isovaleric acid increased from 0.34 mg / kg to 0.55 mg / kg, a 61% increase; furfuryl alcohol increased from 0.53 mg / kg to 0.99 mg / kg, an 87% increase; isoamyl acetate increased from 0.046 mg / kg to 0.46 mg / kg, a 576% increase; furfuryl acetate increased from 0.17 mg / kg to 0.8 mg / kg, a 371% increase; ethyl phenylacetate increased from 0.12 mg / kg to 0.26 mg / kg, a 371% increase; and ethyl phenylacetate increased from 0.12 mg / kg to 0.26 mg / kg. kg, an increase of 117%, phenylethyl acetate increased from 1.41mg / kg to 5.54mg / kg, an increase of 293%, propyl nonanolide increased from 0.34mg / kg to 0.71mg / kg, an increase of 109%, 4-methylguaiacol increased from 1.15mg / kg to 7.66mg / kg, an increase of 385%, and 4-ethylguaiacol increased from 0.2mg / kg to 0.49mg / kg, an increase of 145%.

[0021] After aging at 45°C for 30 days, the Maillard reaction continued, melanoidins gradually accumulated, and L-pyroglutamate increased from 1.47 mg / kg to 2.99 mg / kg, a 103% increase.

[0022] Among the volatile flavor compounds, aldehydes and phenols were significantly increased, with furfural increasing from 4.78 mg / kg to 13.20 mg / kg, a 176% increase. 5-Methylfuraldehyde, 2-phenylcrotonaldehyde, cocaaldehyde, and α-(2-furylmethylene)phenylacetaldehyde were produced exclusively at this temperature, with concentrations of 0.25 mg / kg, 0.16 mg / kg, 1.46 mg / kg, and 0.29 mg / kg, respectively. 4-Vinyl-2-methoxyphenol increased from 0.7 mg / kg to 1.34 mg / kg, a 91% increase. Furthermore, the content of ligustrazine significantly increased to 2.68 mg / kg; phenylethanol increased from 1.6 mg / kg to 2.31 mg / kg, a 44.38% increase; and octanoic acid increased from 0.19 mg / kg to 0.35 mg / kg, an 84.21% increase.

[0023] During aging at all temperatures, the acidity of the mash accumulated, reaching its highest value at 30°C [30d (0.77), 60d (0.78), 90d (0.77)]. The reducing sugar content varied significantly during aging, increasing significantly at 45°C [30d (7.78), 60d (6.16), 90d (5.55)] and fluctuating more significantly at 30°C [30d (5.50), 60d (6.77), 90d (6.41)]. The crude polysaccharide content decreased significantly at 45°C (30 days (5.92), 60 days (4.99), and 90 days (4.09)), but increased significantly at 15°C and 30°C [15°C: 30 days (5.50), 60 days (6.77), and 90 days (6.41)] [30°C: 30 days (7.84), 60 days (6.21), and 90 days (6.85)]. Similar to the changes in reducing sugars, the total amino acid content also fluctuated significantly during aging at 30°C and 45°C, accumulating primarily at 30°C [30 days (18.47), 60 days (20.16), and 90 days (21.64)] and decreasing at 45°C [30 days (21.73), 60 days (16.48), and 90 days (15.86)]. At 30℃, RS was negatively correlated with acidity, indicating that RS was converted into organic acids through microbial action during the aging process, and temperature had a significant effect on microbial fermentation activity.

[0024] Similarly, FAA and CP contents accumulated at 30°C, likely as a result of microbial metabolism through the secretion of numerous hydrolytic enzymes. Furthermore, changes in chemical parameters are not only determined by microbial activity but also by chemical reactions during aging, such as the Maillard reaction. During aging at 45°C, the Maillard reaction was detected to continue, as reflected by an increase in melanoidin levels (absorption at 420 nm). Consequently, RS and FAA levels initially increased sharply and then decreased sharply over time during aging at 45°C, suggesting that the initial increase was the result of glycosidase and protease activity, followed by a continuous decrease due to the Maillard reaction. Maillard products are frequently reported as flavor compounds and antioxidants that can improve vinegar color.

[0025] Among the eight organic acids, lactic acid and acetic acid were found to have the highest content. Lactic acid is the primary non-volatile acid in vinegar, contributing to its mellow taste. Lactic acid content increased significantly during aging at all temperatures, reaching its highest level at 30°C [30 days (28.28), 60 days (30.66), and 90 days (30.21)]. Acetic acid content showed little change, with only a slight increase after aging at 15°C for 90 days [30 days (18.39), 60 days (17.92), and 90 days (18.95)]. In addition to lactic acid, other organic acids can also buffer the pungent flavor of acetic acid, contributing to the unique flavor of vinegar. L-pyroglutamic acid, a product of glutamate metabolism, was found at high levels in bran vinegar and also increased significantly during aging at 30°C [30 days (2.83), 60 days (1.47), and 90 days (3.52)]. During aging at 45°C, l-malic acid content increased significantly [at 30 days (1.40), 60 days (1.91), and 90 days (2.07)]. Phenyllactic acid content fluctuated slightly during aging at 15°C [at 30 days (0.17), 60 days (0.20), and 90 days (0.18)], but decreased significantly at 30°C [at 30 days (0.15), 60 days (0.13), and 90 days (0.15)] and 45°C [at 30 days (0.18), 60 days (0.16), and 90 days (0.14)], potentially indicating that microbial metabolism was most active under these conditions. FAA content increased from 17.21 g / kg to 19.91 g / kg during aging at 30°C; however, due to the Maillard reaction, it decreased significantly to 14.99 g / kg after 90 days at 45°C. Among them, His (histidine), Arg (arginine), Glu (glutamic acid), Ala (alanine), Ser (serine), Gly (glycine), Ile (isoleucine), Thr (threonine), Met (methionine), Phe (phenylalanine), Val (valine), and Leu (leucine) significantly accumulated during aging at 30°C. Except for His (histidine), which decreased significantly during aging at 45°C, the others all decreased significantly. Among them, His (histidine), Glu (glutamic acid), and Ala (alanine) are important taste compounds.

[0026] Overall, aging at 30°C and 45°C significantly altered the chemical parameters of the mash. Aging at 30°C was most beneficial for increasing the contents of organic acids and FAAs, while aging at 45°C significantly decreased the contents of FAAs and RS. However, aging at 45°C [30 days (7.17), 60 days (9.72), and 90 days (10.36)] promoted the accumulation of phenolic compounds and Maillard products.

[0027] With the increase of aging temperature, the content of volatile compounds increased. At 15℃, 30℃ and 45℃, the content of volatile compounds was 11.90-16.52 g / kg, 15.71-29.31 g / kg and 23.10-31.70 g / kg, respectively.

[0028] Volatile acids are important flavor compounds in vinegar, produced through the metabolic processes of various microorganisms during the fermentation process. In addition to acetic acid, butyric acid, 3-methylbutyric acid, hexanoic acid, and octanoic acid are the main volatile acids, characterized by rancid, cheesy, and creamy notes, and significantly contribute to the aroma of vinegar. Among them, 3-methylbutyric acid increases significantly during aging at all temperatures, likely due to microbial metabolic activity, while the levels of other acids are not significantly affected by aging. Esters are the most abundant flavor compounds, and these fruity compounds are mostly key flavor components of vinegar. Isoamyl acetate, 2-furanmethanol acetate, γ-nonanolactone, and phenylethyl acetate increase significantly at all temperatures. Ethyl phenylacetate and ethyl palmitate increase during aging at 30°C and 45°C, while ethyl linoleate increases only at 30°C. These esters are believed to be produced by microbial metabolic activity.

[0029] Aldehydes, with aromas of caramel, almond, cream, and fruit, contribute significantly to the aroma of vinegar. Benzaldehyde, phenylacetaldehyde, furfural, and 5-methylfurfural have been identified as key flavor compounds in many Chinese grain vinegars and Italian balsamic vinegars. During aging, 5-methylfurfural, 2-phenyl-5-methyl-2-hexenal, and α-(2-furylmethylene)phenylacetaldehyde (2-phenyl-3-(2-furyl)-propenal) accumulated only at 45°C. Furfural is primarily produced by the Maillard reaction of pentoses and can also be produced by the oxidation of 2-furyl alcohol, which may explain the weak Maillard reaction and the significant increase in furfural at 30°C. Benzaldehyde can be produced by the oxidation and decarboxylation of phenylalanine and methionine, and roasting can increase benzaldehyde levels. In this study, benzaldehyde increased only during aging at 30°C, likely due to microbial production.

[0030] Phenolic compounds, including cresol, 4-ethylguaiacol, and 2-methoxy-4-vinylphenol, are believed to be produced by lignin degradation and microbial metabolic activity. Creosol content increased dramatically during aging at 30°C, becoming the most abundant phenol during in situ aging of the mash. It can be considered a biomarker of in situ aging. 4-ethylguaiacol and 2-methoxy-4-vinylphenol also increased during aging at 30°C, which may also be related to microbial metabolism. Tetramethylpyrazine has been detected in many brewed vinegars and is known to be produced by the Maillard reaction during thermal processing, with acetoin as its precursor. Therefore, during aging at 45°C, ligustrazine significantly increased, while acetoin was consumed. The loss of acetoin at 15°C and 30°C may be attributed to microbial metabolic activity.

[0031] Overall, based on principal component analysis, it was observed that aging at 30°C and 45°C was most beneficial for improving the flavor compounds of the mash. It is worth noting that microbial metabolic activity had a considerable impact on the formation of flavor compounds during in situ aging at all temperatures, especially at 30°C.

[0032] Table 1 shows the changes in flavor compounds at 15℃, 30℃ and 45℃

[0033]

[0034]

[0035] During the aging process at 30℃, organic acids and amino acids increased significantly; some amino acids increased significantly at this temperature, such as 3-methylbutyric acid (isovaleric acid), isoamyl acetate (Isoamyl acetate), ethyl phenylacetate (Ethylphenylacetate), phenylethyl acetate (Phenethyl acetate), coconut aldehyde (γ-nonanolactone), and phenylacetaldehyde (Benzeneacetaldehyde), which reached the highest level after aging for 60 days, and benzaldehyde (Benzaldehyde), fusel oil (Creosol), and 4-ethylguaiacol (4-ethylguaiacol) reached the highest level after aging for 90 days.

[0036] During the aging process at 45°C, the Maillard reaction can further increase the contents of furfural, 5-methylfurfural, and tetramethylpyrazine in the mash, reaching the highest level after 90 days of aging; and can significantly increase reducing sugars and total amino acids within 30 days of aging.

[0037] In general, aging at 30°C and 45°C is most conducive to improving the flavor compounds of vinegar mash; it is worth noting that at all temperatures, especially during in situ aging at 30°C, microbial metabolic activity has an important influence on the formation of flavor compounds.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for aging vinegar, characterized in that: The following steps are involved: The vinegar mash on the last day of fermentation will be aged under gradient constant temperature control.

2. A vinegar aging method according to claim 1, characterized in that: The gradient constant temperature controlled aging comprises: The first stage of aging is carried out at 28-32℃ for 28-33 days; The wine then undergoes a second aging phase at 42-48°C for 28-33 days.

3. A vinegar aging method according to claim 2, characterized in that: The gradient constant temperature controlled aging comprises: The first stage of aging was carried out at 30°C for 30 days; Then a second stage of aging was carried out at 45°C for 30 days.

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