阅读说明：本技术 一种能提升咖啡豆芳香物质的发酵方法 (Fermentation method capable of improving coffee bean aromatic substances ) 是由 山云辉 于 2020-06-01 设计创作，主要内容包括：本发明公开了一种能提升咖啡豆芳香物质的发酵方法,述的能提升咖啡豆芳香物质的发酵方法包括前处理、发酵和烘焙步骤,本发明是在成熟的咖啡鲜果脱皮完成而没有去除果胶以前,添加适量的可溶性果糖和葡萄糖,让果胶糖度达到20以上,迫使其更多的参与有氧、无氧、加压、恒温恒湿发酵和种子的新陈代谢(seed metabolism)活动,从而转化为咖啡豆的芳香类植物化学成分,进而扩散和渗透到种仁内部,更利于产生更多的咖啡芳香类风味化学物质,使其口感在香气、水果味、花香味、甜度、浓稠度、层次感等方面更加显著。(The invention discloses a fermentation method capable of improving aromatic substances of coffee beans, which comprises the steps of pretreatment, fermentation and baking, wherein a proper amount of soluble fructose and glucose are added before the fresh ripe coffee fruits are peeled without removing pectin, so that the sugar degree of the pectin reaches more than 20, more pectin is forced to participate in aerobic, anaerobic, pressurized, constant temperature and humidity fermentation and seed metabolism (seed metabolism) activities, and then the pectin is converted into aromatic phytochemicals of the coffee beans, and further the aromatic phytochemicals are diffused and permeated into kernels, so that more coffee aromatic flavor chemical substances can be generated, and the taste of the coffee aroma chemical substances is more remarkable in the aspects of aroma, fruit flavor, flower flavor, sweetness, thickness, layering and the like.)

1. A fermentation method capable of improving coffee bean aromatic substances is characterized by comprising the steps of pretreatment, fermentation, drying, shelling and baking, and specifically comprises the following steps:

A. pretreatment:

1) picking fresh coffee fruits, removing immature fruits, over-ripe dried fruits, pest and disease damage fruits and foreign matters, enabling the maturity, particle size and quality of raw materials to be consistent through a color selector and a particle size classifier, and classifying according to the residual degree of pectin after peeling to obtain a material a;

2) adding soluble fructose and/or glucose into the material a until the pectin sugar degree of the material a is more than 20 to obtain a material b;

B. fermentation: carrying out aerobic fermentation and anaerobic fermentation on the material b under the conditions of pressurization, constant temperature and constant humidity to obtain a material c;

C. drying and shelling: naturally drying the material c at low temperature, then shelling, and carrying out color sorting, particle size sorting and specific gravity selection grading to obtain a material d with consistent raw materials;

D. baking: and roasting the material d to obtain the target coffee beans.

2. The fermentation method of claim 1, wherein the peeling in step 1) requires a pectin retention rate of 20% or more.

3. The fermentation method of claim 1 or 2, wherein the peeling requires a pectin retention rate of more than 75%.

4. The fermentation method of claim 1, wherein the sugar degree of pectin in step A2) is 20-40.

5. The fermentation method of improving aroma of coffee beans according to claim 1 or 4, wherein the sugar degree of pectin is 30.

6. The fermentation method of claim 1, wherein the temperature of the aerobic fermentation in step B is 30-40 ℃, the humidity is 60-80%, the pressure is 0.1-0.5 MPa, and the fermentation time is 60-80 hours.

7. The fermentation method for improving aroma of coffee beans according to claim 1, wherein the anaerobic fermentation in step B is carried out at a temperature of 18 to 20 ℃, a humidity of 40 to 60%, a pressure of 0.1 to 0.5MPa, and a fermentation time of 30 to 60 hours.

8. The fermentation method of claim 1, wherein the natural low temperature drying in step C is natural drying in an environment without direct contact with the ground and without direct sunlight.

9. The fermentation method for improving aroma of coffee beans according to claim 1, wherein in the roasting process in the step D, the pressure value of the liquefied gas tank is adjusted to 30-150KPa, the roasting time is 9-15 min, the roasting temperature is 110-220 ℃, and the temperature for taking out of the pot is 195-208 ℃.

10. The fermentation method of claim 1, wherein the roasting in step D is Light-medium roasting, which is suitable for one of Light roasting (Light), darker roasting (Cinnamon), lighter-medium roasting (Media), medium roasting (High), lighter-medium roasting (City), and normal roasting (Full City).

Technical Field

The invention belongs to the technical field of deep processing of food, and particularly relates to a fermentation method capable of improving aromatic substances of coffee beans.

Background

Coffee is a beverage made from roasted coffee beans, and is a popular main beverage in the world together with cocoa and tea. Coffee is made by matching coffee beans with various cooking devices, wherein the coffee beans refer to kernels in coffee fruits and are baked by a proper method.

Disclosure of Invention

The invention aims to provide a fermentation method capable of improving coffee bean aromatic substances.

The invention aims to realize that the fermentation method capable of improving the aroma of the coffee beans comprises the steps of pretreatment, fermentation, drying and shelling and baking, and specifically comprises the following steps:

A. pretreatment:

1) picking fresh coffee fruits, removing immature fruits, over-ripe dried fruits, pest and disease damage fruits and foreign matters, enabling the maturity, particle size and quality of raw materials to be consistent through a color selector and a particle size classifier, and classifying according to the residual degree of pectin after peeling to obtain a material a;

2) adding soluble fructose and/or glucose into the material a until the pectin sugar degree of the material a is more than 20 to obtain a material b;

B. fermentation: carrying out aerobic fermentation and anaerobic fermentation on the material b under the conditions of pressurization, constant temperature and constant humidity to obtain a material c;

C. drying and shelling: naturally drying the material c at low temperature, then shelling, and carrying out color sorting, particle size sorting and specific gravity selection grading to obtain a material d with consistent raw materials;

D. baking: and roasting the material d to obtain the target coffee beans.

The principle of the invention is as follows: the essential meaning of the method for the fermentation treatment of the wet coffee beans is to ferment and decompose pectin of the green coffee beans, and polysaccharide substances in the coffee are decomposed and converted into alcohols, acetic acid, lactic acid and other acid substances by virtue of microorganisms and enzymes of the coffee. Many in the industry believe that the sugars and fruity notes in pectin (pulp)/mucine and pericarp/pulp diffuse/penetrate through the coffee bean Husk (husks) into the coffee seeds. Unfortunately, this assumption lacks any scientific data. In contrast, the relevant papers of many researchers in the world have demonstrated that coffee bean Husk (Husk) is a high density, non-porous seed shell, and that many nutrients, including sucrose (in different coffee fresh fruit processing methods), do not diffuse through the bean Husk into the seed.

According to the invention, through a plurality of times of fermentation experiments of different sugars, a certain kinds of fructose and glucose (based on different treatment methods) are suddenly discovered, and can participate in metabolism of coffee seeds (seed metabolism) through fermentation of coffee pectin, so that the fructose and glucose are converted into aromatic phytochemical components of coffee beans, and then the components are diffused and permeated into kernels, and the components become key factors for improving sweetness and aromatic substance content of the coffee drink and enriching mouthfeel of coffee after entering the interior of the coffee beans.

1. The pectin fermentation of coffee beans is found to participate in the metabolism mechanism of coffee beans:

(1) after the fresh coffee fruits are picked, immature fruits, over-ripe dried fruits, pest and disease fruits and foreign matters are removed, and the amount of molecules/molecules (such as isocitrate lyase components, beta tubulin) related to the seed germination/development mechanism is measured, we can see the difference between fermentation after peeling and direct drying treatment of coffee beans without peeling. The number of molecules (molecules associated with the seed germination/development mechanism) in the dehulled treated coffee peaks within two days after harvest, beginning to decrease dramatically after about one week, while in the de-skinned direct-dried treated coffee, these molecular numbers peak only one week after harvest and then decrease slowly. These two factors explain this phenomenon, firstly, the possible presence of some inhibitors in the pectin of coffee slows the germination process of the seeds, secondly, the rapid drying of the coffee by the post-peel fermentation treatment allows rapid attainment of the cell quiescence, and the coffee without peel direct drying treatment requires more time to dry to cell quiescence because of its higher mass and moisture content.

(2) The second response is related to the "water deficit/water stress" of the plant (note: water deficit-when the water in the environment is insufficient to provide the plant with the need to sustain life, or when the environment has enough water but is affected by other conditions and the plant cannot take up this water, we say that (water stress). the coffee dried directly without peeling accumulates more gamma-aminobutyric acid (GABA) in the cells of the water-stressed plant than the coffee fermented after peeling, this is because it takes longer for the coffee dried directly without peeling to start its metabolism. Changes in the same treatment, but slight steps or only fine adjustments in fermentation time, result in different flavors, as demonstrated in numerous experiments, which are the guiding flavors of the primary coffee processing as follows: direct drying treatment method without peeling: lower acidity, more obvious sweetness, the clearest touch (Mouthfeel) and slightly lower cleanliness; and (3) a fermentation water washing treatment method after peeling: the acidity is obvious, the cleanliness is good, the touch feeling (Mouthfeel) is moderate, and the quality of the raw beans is the most consistent; and (3) fermentation treatment after peeling: moderate acidity, better sweetness than water washing, better cleanliness than sun drying, and moderate touch.

2. It was found that in the case of pectin participating in the fermentation treatment, the longer the fermentation time, the longer the time required for the microbial activity to develop, and the better the fermentation effect. This fermentation effect persists on the coffee bean hulls, as evidenced by higher concentrations of microbial metabolites, such as lactic acid and mannitol (with sucrose-like sweetness), and higher concentrations of floral or fruity volatile organic compounds. On the other hand, during long-term fermentation, the metabolism of coffee beans enhances the anaerobic effect, and affects the concentrations of carbohydrates (e.g., glucose and fructose), amino acids (e.g., aspartic acid and alanine), and organic acids (e.g., succinic acid). These compounds can be used as the main precursors for a series of chemical reactions in the next baking process. In particular, the degradation of mono-and polysaccharides in the maillard reaction during baking produces sweet and caramelised aromas. In contrast, the degradation of hydroxycinnamic acid, a phenolic compound, produces the aroma of a fragrance. Hydroxy amino acids such as threonine and serine are converted to volatile compounds called pyrazine and pyrrole, giving rise to the characteristic odor of coffee roasting. And produces a unique coffee flavor. With the change in the richness of these flavor precursors, longer fermentation times resulted in enhanced fruit flavor in coffee, which factors greatly improved the mouthfeel of coffee.

3. During the fermentation process of pectin, the coffee pectin content maintained during the peeling of fresh coffee has great influence on the flavor of coffee bean. The higher the pectin content is, the more active the microorganism activity is, the aromatic phytochemical components which are converted into coffee beans are further diffused and permeated into the kernels, the more flavor substances are formed, and the better the taste and flavor of the coffee are. Therefore, pectin is well preserved as much as possible when fresh coffee fruits are peeled, and classification is carried out according to the estimation degree of the pectin retention rate: 20-30% is white honey grade, about 60% is yellow honey grade, about 75% is red honey grade, and about 80% is black honey grade. The invention needs to control the pectin retention rate to be more than 20 percent and approach to more than 80 percent as much as possible, thereby achieving the black honey grade.

4. We found that during the fermentation process of pectin, river oligospore (R. oligosporus) can be added to greatly produce the necessary elements for promoting the generation of flavor substances, and Pichia pastoris (Pichia pastoris) can be added to promote the generation of flavor substances such as vanilla and flower fragrance. The pectin decomposition can be promoted by adding streptomyces marxianus (s.marxianus), streptococcus pasteurii (s.bayanus), streptococcus ellipsoidea (s.cerevisiae var. ellipsoidea), and the like.

5. The pectin sugar degree was found to have a large influence on the formation of coffee bean flavour.

Under the conventional condition, the pectin sugar degree value of the coffee cherry with insufficient maturity is lower, and the pectin sugar degree with high maturity is high. Therefore, all tests and results in the invention are calculated according to the highest value of the sugar degree of the pectin, wherein the coffee cherry is well-cooked and does not turn black. In a large number of experiments, we found that conventional coffee pectin has a sugar degree of 15-16 and a popular general level of mouthfeel; the pectin sugar degree of low altitude and poor planting environment management measures is generally lower than 8-12, and the taste is bitter and flat; the pectin with excellent high altitude and planting environment management measures has the sugar degree of about 20 generally, even as high as 30, obvious coffee aroma, strong fruit and flower flavors, high sweetness and consistency, rich layering and excellent overall taste. Therefore, the product test is made by selecting different saccharides in a breakthrough manner and improving the sugar degree of pectin after the addition, and the addition of sucrose and insoluble saccharides (before the peeling of the fresh coffee fruits is finished and the pectin is not removed) is found to have no influence on the quality and the taste of the coffee; and fructose and glucose with high solubility are added, so that the coffee has a very remarkable effect on enhancing the quality of coffee, such as aroma, sweetness, flavor, layering and the like.

6. Results of different fermentation treatments after addition (fructose and glucose):

the fermentation treatment is divided into two types according to the degree of oxygen (air) participation: aerobic fermentation and anaerobic fermentation. In general, most of the conventional treatment methods are 'aerobic' fermentation, and the recent industry develops anaerobic fermentation treatment, which is based on the following principle:

C₆H₁₂O₆(glucose, etc.) +2ADP +2phosphate → 2lactic acid (lactic acid) +2ATP

C₆H₁₂O₆→2C₂H₅OH (ethanol) +2CO₂↑+2ATP

Aerobic fermentation is generally natural standing fermentation, and tests show that after soluble fructose and glucose are added, the flavor is optimal when the fermentation time reaches 72 hours. While anaerobic fermentation is generally conducted in a sealed environment without oxygen or submerged in water. The ethanol in the anaerobic fermentation treatment can be subjected to esterification reaction with other organic acids (such as lactic acid) to generate ester compounds with flower and fruit fragrance. Therefore, the anaerobically fermented coffee beans have both bouquet and red wine-like body and also flower-like cheese-like flavor. It can also be seen that how much gum is retained, i.e. how much sugar is present, is also important for the taste after fermentation. Careful screening of the beans prior to processing is required as factors such as the maturity, variety, seasonality and water and soil of the coffee also affect the quality of the pectin, particularly the glucose content. The fermentation process affects the balance of these flavors. Anaerobic fermentation easily controls the internal environment. For example, temperature, humidity, gas concentration, pH, etc., may control the type and amount of bacteria involved in fermentation. The temperature is controlled to 4-8 ℃ if beans with more complex acids are required and 18-20 ℃ if beans with higher sugar degrees are required. And controlling the fermentation reaction time, such as when pectin and sugar in mucus are completely consumed, immediately unsealing and stopping the fermentation, and immediately drying in the sunlight to avoid over-fermentation.

Pressure honey treatment, namely putting the coffee beans with peel or part of pectin removed into a stainless steel barrel for fermentation, and generating pressure which gradually raises in a closed container. In contrast, the "carbon dioxide impregnation method" is a method in which the whole coffee beans are put into carbon dioxide gas (i.e., in an oxygen-free state), that is, the coffee beans are kept intact before entering the sealed can. Thus, even in the absence of yeast, the coffee fruit itself converts its sugar into alcohol, and the remaining steps are largely different from the anaerobic fermentation treatment method. Because the peel of the fresh coffee fruit is left intact, fermentation proceeds slowly and occurs almost entirely within the fruit, which may take days or even weeks. The wine brewed by the method has soft fragrance, rich taste and stable color.

7. Through the repeated tests, the results show that: before the fresh coffee fruits are peeled without removing pectin, a proper amount of soluble fructose and glucose are added, so that the sugar degree of the coffee pectin reaches more than 20, the optimal range is 20-40, more coffee pectin is forced to participate in the fermentation process and the metabolic activity of seeds under the aerobic, anaerobic, pressurized, constant temperature and constant humidity conditions of the pectin, and the coffee pectin diffuses and permeates into coffee beans through bean shells, so that more coffee aromatic flavor chemical substances are generated, the coffee has more obvious aroma, stronger fruit flavor and flower flavor, higher sweetness and thickness, richer layering and obviously improved overall mouthfeel.

Coffee pectin is a colloidal substance between the pericarp and the hull of ripe coffee cherries, located in the primary cell wall and intercellular spaces (the middle layer), and is composed of complex and diverse polysaccharides such as the residue of sugar, D-galacturonic acid, and other components. The invention discloses a method for preparing coffee aroma, which is characterized in that a proper amount of soluble fructose and glucose are added before peeling of a fresh ripe coffee fruit is finished without removing pectin, so that the sugar degree of the pectin reaches more than 20, more pectin is forced to participate in aerobic, anaerobic, pressurized, constant-temperature and constant-humidity fermentation and metabolic activities of seeds, and the pectin is diffused and permeated into coffee beans through bean shells, so that more coffee aroma flavor chemical substances are generated, and the taste of the coffee aroma, fruit flavor, flower aroma, sweetness, thickness, layering and the like is more obvious.

8. Through repeated tests, the coffee beans produced by the technical process have high product consistency, richer aromatic flavor chemical substances and more remarkable mouthfeel in aspects of aroma, fruit flavor, flower aroma, sweetness, thickness, layering and the like. However, in the final baking process, the degree of baking also greatly affects the content of aromatic flavor chemicals and the degree of flavor expression. Except that the ultra-hard beans and special varieties produced at ultra-high altitude need to be slightly deeper than the conventional baking degree, the excellent mouthfeel and various rich flavors such as fruit acid, flower fragrance and the like can be displayed to a greater degree by shallow baking in general, so the baking technical requirements grasped by people are as follows: adjusting the pressure value of the liquefied gas tank to be 30-150kpa, baking for 9-15 minutes, gradually raising the baking temperature to about 220 ℃ from about 75-120 ℃ of the temperature of the entering beans, and recommending that the soybean is taken out of the pot under the condition of 195-208 ℃ after the first explosion, wherein the optimal temperature for taking out the soybean is 198-205 ℃; if the roasting degree of the coffee is gradually deepened when the temperature of the coffee pot exceeds 208 ℃, the aroma substances of the coffee with different roasting degrees are identified by adopting an optimized method and combining GC-MS and PCA analysis is carried out on the classified aroma substances, so that the relative percentage content of flavor precursors such as pyrazine furans, aldehyde compounds, acids and the like is gradually reduced, the total amount of volatile components such as pyridine compounds, phenol compounds and the like is gradually increased, and the flavor and taste of the coffee tartaric acid, the aroma substances and the like are weakened along with the deepening of the oxidative decomposition of fat, the Maillard reaction and the caramelization reaction; if the temperature of the pot is over 220 ℃, the good flavor taste of fruit sourness, flower fragrance, fruit taste and the like is greatly reduced or is covered by burnt bitter taste. Therefore, the coffee beans of the present invention are recommended to be Light and medium roasted, suitable for Light (Light), Light and dark (cinmamon), Light and medium (Media), medium (High), Light and medium (City), and normal (Full City) roasting methods, and not suitable for medium (Light French), French (French), and deep (Italian/Full French) roasting methods.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to be limiting in any way, and any modifications or alterations based on the teachings of the present invention are intended to fall within the scope of the present invention.

The fermentation method capable of improving the aroma of the coffee beans comprises the steps of pretreatment, fermentation, drying, shelling and baking, and specifically comprises the following steps:

A. pretreatment:

1) picking fresh coffee fruits, removing immature fruits, over-ripe dried fruits, pest and disease damage fruits and foreign matters, enabling the maturity, particle size and quality of raw materials to be consistent through a color selector and a particle size classifier, and classifying according to the residual degree of pectin after peeling to obtain a material a;

2) adding soluble fructose and/or glucose into the material a until the pectin sugar degree of the material a is more than 20 to obtain a material b;

B. fermentation: carrying out aerobic fermentation and anaerobic fermentation on the material b under the conditions of pressurization, constant temperature and constant humidity to obtain a material c;

C. drying and shelling: naturally drying the material c at low temperature, then shelling, and carrying out color sorting, particle size sorting and specific gravity selection grading to obtain a material d with consistent raw materials;

D. baking: and roasting the material d to obtain the target coffee beans.

The peeling in the step 1) needs to control the pectin retention rate to be more than 20%.

The peeling needs to control the pectin retention rate to be more than 75%.

The sugar degree of the pectin in the step A2) is 20-40.

The sugar degree of the pectin is 30.

And B, the temperature of aerobic fermentation in the step B is 30-40 ℃, the humidity is 60-80%, the pressure is 0.1-0.5 MPa, and the fermentation time is 60-80 h.

And B, performing anaerobic fermentation at the temperature of 18-20 ℃, at the humidity of 40-60%, under the pressure of 0.1-0.5 MPa, and for 30-60 h.

And C, naturally drying at low temperature in an environment without direct contact with the ground and direct sunlight.

And D, in the baking process in the step D, adjusting the pressure value of the liquefied gas tank to be 30-150KPa, baking for 9-15 min, baking at the temperature of 110-220 ℃ and taking out of the pot at the temperature of 195-208 ℃.

The baking in step D is Light moderate baking, which is one of Light baking (Light), darker baking (Cinnamon), lighter moderate baking (Media), moderate baking (High), lighter moderate baking (City), and normal baking (Full City).

The invention is further illustrated by the following specific examples: