Do the flavors of liquor really exist?

When it comes to liquor, there are many types. From the legendary Du Kang brewing wine to the present, it is estimated that there are no less than a thousand kinds of liquor. However, people still classify liquor, one of the basis is the aroma.

There are different classifications of the flavor of liquor. For example, the most common ones are sauce-flavored, light-flavored, strong-flavored, and mixed-flavored. Of course, some even classify it into more than ten flavors.

Do wine aroma types really exist? People who know wine can tell them apart. It is said that many wine drinkers can tell the difference between different aroma types, and even between different wines of the same aroma type. Some even can tell the year by the aroma type. However, many people think that all liquors taste the same, and it is difficult to tell the aroma type.

So, is the aroma of wine a metaphysics or is there a scientific basis? Let's talk about this question.

01. The Determinant of Fragrance Type - Ingredients

First of all, we don't need to mythically describe the flavor of liquor. In fact, with the development of chemistry today, liquor, as a mixture, is not indistinguishable. We can find out where its flavor comes from by analyzing its components with modern chemical instruments.

The main ingredient of liquor is alcohol, or ethanol. As a pure compound, the taste of ethanol is the same whether it is brewed from corn, sorghum, or even directly synthesized industrially. Ethanol has the same taste.

The main differences in the flavor of liquor lie in the ingredients other than ethanol, and these ingredients, or flavor substances, vary among different liquors.

For example, in the study “Cluster Analysis and Principal Component Analysis of Different Flavor Types of Liquor”, the authors selected five common liquor flavor types, namely strong aroma, light aroma, sauce aroma, sesame aroma and special aroma [1].

Of course, different brands of liquor are selected for each flavor, such as 9 types of strong aroma (N1-N9), 2 types of light aroma (Q1, 2), 3 types of sauce aroma (J1-3), and 1 type of special aroma.

Next, chromatography and mass spectrometry were used to identify the components in the liquor.

First of all, white wine contains a lot of ingredients

These ingredients include many types. For example, the figure below shows the performance of some ingredients when clustered. Ethyl caproate, butyric acid, isobutanol, ethyl palmitate, furfural, furan methanol, etc. are all ingredients in white wine.

Then, by classifying according to the cluster analysis method, we can see that the clusters of different types of liquor are really different.

For example, the N series of strong-flavored flavors will be grouped together, while the Q series of light-flavored flavors will also be grouped together. It can be seen that different flavors do have differences, and these differences include differences in both the types of ingredients and the proportions of ingredients.

It is this difference that causes different wines to have different aromas. Some people taste wine frequently or have richer taste buds, so they can taste the flavor of the wine.

So, where does this flavor difference come from? The root of it lies in the fermentation of liquor.

02. Fermentation: The Root of Flavor

Liquor is brewed from grains, so the fundamental difference between liquors lies in fermentation. The factors that affect fermentation mainly include:

1. Raw materials

Different liquors are fermented from different grains, and these grain differences themselves will lead to differences in fermentation results.

For example, Moutai uses sorghum and wheat for fermentation, Fenjiu uses sorghum, and Wuliangye uses sorghum, rice, glutinous rice, wheat and corn.

In fact, many grains can be used to make wine, such as glutinous rice, buckwheat, peas, and even potatoes.

These fermentation raw materials each have their own flavor, and in the process of forming wine, their own flavor will inevitably be extracted, thus forming a unique aroma.

In addition to the raw materials, another important factor also has an impact, that is, fermentation microorganisms.

2. Fermentation Microorganisms

Liquor is fermented with yeast, but yeast is a very large family, so each family has its own unique yeast strains.

In particular, many wineries have a very long history, and these fermentation pools have also formed a unique ecology, resulting in differences in winemaking.

We take the earliest, largest and most complete existing Wuliangye ancient cellar from the Ming and Qing dynasties in my country as an example to explore the microbial conditions of these fermentation pools. This fermentation pool can be traced back to 1368 AD and has been fermenting without interruption since the Ming Dynasty. It is the oldest continuous fermentation pool that can be verified and is also my country's intangible cultural heritage.

Researchers used advanced high-throughput sequencing technology to study the microbial community structure of Wuliangye pit mud and found that there are actually many types of microorganisms in the fermentation tank[2]

For example, in the koji, there are both common yeasts and bacteria and molds, and not just one type of microorganism. For example, yeast includes brewer's yeast, the basic ingredient for brewing, and tropical Candida.

In fact, not only these organisms, but also prokaryotes are very complex.[3]

A total of 19 phyla of microorganisms were detected in the fermentation tank, including Euryarchaeota, Crenarchaeota, Acidobacteria, Acinobacteria, Bacteroidetes, Chlamydiae, and 7 unnamed phyla (AC1, FBP, OP9, TM7, WS1, WWE).

Such a complex microbial community is also the main factor that ultimately leads to brewing differences.

From the above introduction, we can see that fragrance is not pseudoscience, but real chemical and biological differences.

So, what’s the point of all this technology?

03. Technology empowers the future

In recent years, technology has made great progress, and these technologies have been well reflected in brewing. The research we mentioned above is an example of this.

In fact, these analyses have already formed many applications, a typical example being liquor identification.

Nowadays, the price of high-end liquor is high, which has also caused a big problem of counterfeiting. How to identify the authenticity? Using methods such as chemical chromatography is a good strategy.

Many famous and precious liquors have already established stable production, so their products often contain stable ingredients, that is, chromatographic fingerprints. By comparing the tested liquor with the standard chromatographic fingerprint, the authenticity can be well detected.

In the future, this kind of research can also promote the off-site production of liquor and realize new production of liquor by simulating microbial communities and fermentation environments.

References:

[1] Qian Chong, Liao Yonghong, Liu Mingyan, Xu Jin, Liu Li, Yu Li. Cluster analysis and principal component analysis of different flavor liquors[J]. Journal of Chinese Institute of Food Science and Technology, 2017, 17(02): 243-255.

[2] Zhao Dong, Niu Guangjie, Peng Zhiyun, Chen Liang, Yang Rong. Changes in microbial flora and evolution of physicochemical factors in Wuliangye Baobaoqu [J]. Brewing Technology, 2009(12):38-40.

[3] Zhao Dong, Zheng Jia, Peng Zhiyun, Lv Xuelan, Yang Kangzhuo, Zhang Jianmin. Analysis of the prokaryotic microbial community structure of Wuliangye cellar mud using high-throughput sequencing technology[J]. Food and Fermentation Industries, 2017, 43(09): 1-8.