Instant coffee and preparation method thereof
Technical Field
The invention relates to instant coffee and a preparation method thereof.
Background
Instant coffee (soluble coffee/instant coffee) is a food material commonly available on the market, and is defined as, according to GB/T29602 "solid beverage", the following: the solid beverage is prepared from coffee bean and/or coffee product (ground coffee powder, coffee extract or its concentrate) as raw materials, and optionally food additive without other food adjuvants. Instant coffee is one of the solid coffee beverages and is an important raw material for instant coffee beverages.
The instant coffee product is prepared with green coffee bean and through roasting, grinding, extracting, concentrating, spray drying, packing and other technological processes. At present, the aroma and flavor quality of instant coffee products is improved by adding coffee essence or coffee extract to coffee concentrated solution before spray drying in commercially available instant coffee enterprises. The instant coffee product obtained by the method meets the market demand to a certain extent, but has the problem of consumer acceptance of adding the artificially synthesized essence, and meanwhile, the method of adding before spray drying still has the problem of aroma loss in the spray drying process.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a preparation method of instant coffee.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method of preparing instant coffee, the method comprising the steps of:
(1) roasting green coffee beans, and then grinding the green coffee beans to the fineness of 5-35 meshes to obtain ground coffee powder;
(2) extracting the ground coffee powder obtained in the step (1) with water at 170-200 ℃ and 0.8-1.6 MPa, wherein in the extraction process, when the mass of extracted liquid is a set value, the extracted liquid is used as an aromatic liquid raw liquid, continuing extraction, and taking the residual extracted liquid as a low-aroma extract liquid;
(3) distilling and separating the aromatic liquid stock solution obtained in the step (2) to obtain aromatic liquid and low-aroma liquid components;
(4) distilling the aromatic liquid obtained in the step (3) at 50-65 ℃ and under the vacuum degree of-0.07-0.09 Mpa, collecting gas generated by distillation, and condensing to obtain concentrated aromatic liquid and aromatic liquid residual liquid;
(5) mixing the low-fragrance liquid component obtained in the step (3) and the low-fragrance extraction liquid obtained in the step (2), and concentrating until the solid content is 45-50% to obtain a concentrated solution;
(6) combining and uniformly mixing the aromatic liquid residual liquid obtained in the step (4) and the concentrated liquid obtained in the step (5) to obtain concentrated coffee liquid;
(7) carrying out spray drying on the concentrated coffee liquid obtained in the step (6) to obtain coffee dry powder;
(8) and (5) atomizing the concentrated aromatic liquid obtained in the step (4), and mixing the atomized concentrated aromatic liquid with the coffee dry powder obtained in the step (7) to obtain the instant coffee.
Coffee is perennial evergreen shrub or small arbor of the genus coffee (Coffea) of the family Rubiaceae (Rubiaceae), native to the central and northern part of africa, and is now widely grown in tropical and subtropical regions such as asia, africa, latin america, oceania, and the like. Raw coffee beans, which are endosperm parts of coffee fruits, are prepared by using ripe fresh coffee fruits (Cherry coffee) as raw materials and performing dry processing (main process flow: fruit drying, peeling, air removing and screening classification) or wet processing (main process flow: cleaning, peeling, fermenting, bean washing, soaking, drying, peeling, polishing, classifying and sorting). There are two categories of coffee commonly used for drinking: arabica coffees (Arabica coffee) and Robusta coffees (rofusta coffee, Coffea canephora).
Further, the baking temperature in the step (1) is 160-230 ℃, and the baking time is 10-20 min.
Further, in the step (2), the set value is greater than or equal to 20% of the mass of the total extracted effluent.
Further preferably, the set value is 20-30% of the total mass of the extracted liquid.
In the invention, all extracted liquid can be used as aromatic liquid raw liquid to be subjected to distillation separation treatment to recover aromatic substances in the extraction liquid, but in the actual operation process, when the extracted liquid accounts for 20-30% of the total extracted liquid mass, the content of the aromatic substances in the extraction liquid is relatively high, and the total amount of the extraction liquid is not much and is easy to further treat. Therefore, the extracted liquid is more preferably used as the raw aromatic liquid when the mass of the extracted liquid is 20-30% of the total mass of the extracted liquid.
Further, in the step (2), the extraction time is 10min to 45 min.
Further, in the step (3), the distillation is performed at 120 to 140 ℃ and 0.31 to 0.33 MPa.
Further preferably, in the step (3), the distillation separation is performed as follows: and (3) feeding the aromatic liquid stock solution obtained in the step (2) into a flash tank, feeding the steam obtained by flash evaporation into a distillation tower for distillation, collecting gas generated by distillation and condensing to obtain the aromatic liquid, and collecting the liquid at the bottom of the distillation tower to obtain the low-aroma liquid component, wherein the condensing temperature of condensation is 4-10 ℃.
Further, in the step (5), the concentration is carried out at 50 ℃ to 80 ℃ under a vacuum degree of-0.07 MPa to-0.09 MPa.
Further, in the step (5), triple effect falling film concentration is adopted for concentration.
Further, in the step (4), the cooling substance used for condensation is water with the temperature of 0-1 ℃.
Further, in the step (4), a rotary evaporator is adopted for the distillation.
Further, in the step (8), the mixing is carried out in a fluidized bed with a spray head, which is embodied as follows: and (4) conveying the coffee dry powder obtained in the step (7) into a fluidized bed, atomizing the strong aromatic liquid obtained in the step (4) by using the atomizing head, and mixing the atomized strong aromatic liquid with the coffee dry powder in the fluidized bed.
The related equipment is conventional and universal equipment in the industry.
Preferably, the spray drying equipment used for spray drying employs a spray drying tower manufactured by kagaku, suzhou food industry ltd. This spray drying tower, including nozzle, drying tower entry end and drying tower body, the nozzle sets up on the drying tower entry end, and the quantity of nozzle is three at least, and the nozzle is evenly set up along same circumference. The concrete structure is as described in the utility model with application number 201020022379.3.
The invention adopts another technical scheme that: an instant coffee is prepared by the above preparation method.
Due to the implementation of the technical scheme, compared with the prior art, the invention has the following advantages:
the instant coffee provided by the invention takes raw coffee beans as a raw material, in the production process of the instant coffee, aroma substances are recovered to obtain coffee aroma liquid, low-temperature rectification technology is adopted to collect low-moisture high-concentration coffee aroma liquid, the high-concentration coffee aroma liquid is atomized and then is mixed with the spray-dried coffee dry powder, an instant coffee product with strong aroma and good aroma quality is produced, the product aroma is strong, all indexes meet the product execution standard, and the content of the aroma substances is higher than that of the instant coffee prepared by a conventional production method by more than 40%.
The preparation method of the invention can greatly reduce the loss of aroma in the coffee production process.
Drawings
FIG. 1 is SPME-GC-MS analysis spectrum of instant coffee aroma of example 1 and comparative example 1.
Detailed Description
The invention creatively invents an instant coffee product with strong aroma and good aroma quality by taking raw coffee beans as raw materials and comprehensively using aroma recovery equipment, a rotary evaporator and a fluidized bed (for dense aroma liquid atomization backfilling), wherein the product has strong aroma, all product indexes meet product execution standards, and the content of aromatic substances is higher than that of instant coffee by more than 40 percent compared with the conventional production method.
The invention is further described with reference to specific examples.
Example 1
Taking 10 tons of Vietnam Robusta secondary coffee beans and 100 tons of drinking water, and preparing instant coffee according to the following steps:
(1) roasting the coffee beans for 700-750 s under the condition of 160-230 ℃ (roasting curve temperature variation range) to obtain roasted coffee beans;
(2) grinding the roasted coffee beans obtained in the step (1) on a coffee bean grinder to 30 meshes to obtain ground coffee powder;
(3) conveying the ground coffee powder obtained in the step (2) to an extraction tank for extraction with water, wherein the extraction temperature is 175 ℃, the extraction pressure is 1.0MPa, the extraction time is 25min, and in the extraction process, when the mass of extracted liquid is 25% of the total mass of extracted liquid, the extracted liquid serves as aromatic liquid raw liquid (25 tons), residual water is continuously extracted, and the residual extracted liquid serves as low-aroma extract liquid (75 tons);
(4) and (3) directly conveying the aromatic liquid stock solution obtained in the step (3) to a flash tank, feeding the steam obtained by flash evaporation into a distillation tower for distillation, collecting gas generated by distillation and condensing to obtain aromatic liquid, and collecting the liquid at the bottom of the distillation tower to obtain a low-aroma liquid component, wherein the distillation is carried out at the temperature of 135 ℃ and the pressure of 0.32MPa, and the cooling substance used for condensation is water at the temperature of 4 ℃.
(5) And (3) adding the aromatic liquid obtained in the step (4) into a rotary evaporator, fractionating at 60 ℃ and under the vacuum degree of-0.08 Mpa to volatilize the aroma substances, introducing the aroma substance gas into a condenser, and condensing with ice water at 1 ℃ to obtain condensed liquid, namely the concentrated aromatic liquid, wherein the content of the aroma substances in the concentrated aromatic liquid is about 4%, and the residual aromatic liquid at the bottom of the evaporator is aromatic liquid residue.
(6) Mixing the low-fragrance liquid component obtained in the step (4) and the low-fragrance extraction liquid obtained in the step (3), concentrating to obtain a concentrated solution with a solid content of 45%, concentrating by adopting triple effect falling film concentration, and performing at 60 ℃ and under a vacuum degree of-0.08 Mpa;
(7) combining and uniformly mixing the aromatic liquid residual liquid obtained in the step (5) and the concentrated liquid obtained in the step (6) to obtain concentrated coffee liquid;
(8) spray drying the concentrated coffee liquid obtained in the step (7) to obtain coffee dry powder;
(9) and (3) conveying the coffee dry powder obtained in the step (8) into a fluidized bed with a spray head, atomizing the concentrated aromatic liquid obtained in the step (5) by the spray head, and mixing the atomized concentrated aromatic liquid with the coffee dry powder in the fluidized bed to obtain the instant coffee, wherein the total amount of aroma substances in the instant coffee is 253.04 mu g/kg.
Example 2
Taking 10 tons of Yunnan Arabica three-level coffee beans and 200 tons of drinking water, and preparing instant coffee according to the following steps:
(1) roasting the coffee beans for 750s under the condition of 160-230 ℃ (roasting curve temperature variation range) to obtain roasted coffee beans;
(2) grinding the roasted coffee beans obtained in the step (1) on a coffee bean grinder to 5 meshes to obtain ground coffee powder;
(3) conveying the ground coffee powder obtained in the step (2) to an extraction tank for extraction with water, wherein the extraction temperature is 170 ℃, the extraction pressure is 0.9Mpa, the extraction time is 40min, and in the extraction process, when the mass of extracted liquid is 30% of the total mass of extracted liquid, the extracted liquid serves as aromatic liquid raw liquid (25 tons), residual water is continuously extracted, and the residual extracted liquid serves as low-aroma extract liquid (75 tons);
(4) and (3) directly conveying the aromatic liquid stock solution obtained in the step (3) to a flash tank, feeding the steam obtained by flash evaporation into a distillation tower for distillation, collecting gas generated by distillation and condensing to obtain aromatic liquid, and collecting the liquid at the bottom of the distillation tower to obtain a low-aroma liquid component, wherein the distillation is carried out at the temperature of 140 ℃ and the pressure of 0.31MPa, and the cooling substance used for condensation is water at the temperature of 6 ℃.
(5) And (3) adding the aromatic liquid obtained in the step (4) into a rotary evaporator, fractionating at 50 ℃ and under the vacuum degree of-0.09 Mpa to volatilize the aroma substances, introducing the aroma substance gas into a condenser, and condensing with ice water at 1 ℃ to obtain condensed liquid, namely the concentrated aromatic liquid, wherein the content of the aroma substances in the concentrated aromatic liquid is about 6.5%, and the residual aromatic liquid at the bottom of the evaporator is aromatic liquid residue.
(6) Mixing the low-fragrance liquid component obtained in the step (4) and the low-fragrance extraction liquid obtained in the step (3), concentrating to obtain concentrated solution with solid content of 50%, concentrating by triple effect falling film concentration, and performing at 80 deg.C and vacuum degree of-0.07 Mpa;
(7) combining and uniformly mixing the aromatic liquid residual liquid obtained in the step (5) and the concentrated liquid obtained in the step (6) to obtain concentrated coffee liquid;
(8) spray drying the concentrated coffee liquid obtained in the step (7) to obtain coffee dry powder;
(9) and (3) conveying the coffee dry powder obtained in the step (8) into a fluidized bed with a spray head, atomizing the concentrated aromatic liquid obtained in the step (5) by the spray head, and mixing the atomized concentrated aromatic liquid with the coffee dry powder in the fluidized bed to obtain the instant coffee, wherein the total amount of aroma substances in the instant coffee is 318.54 mu g/kg.
Example 3
Taking 5 tons of Vietnam Robasta secondary coffee beans, 5 tons of Yunnan Arabica tertiary coffee beans and 160 tons of drinking water, and preparing instant coffee according to the following steps:
(1) roasting the coffee beans for 700s under the condition of 160-230 ℃ (roasting curve temperature change range) to obtain roasted coffee beans;
(2) grinding the roasted coffee beans obtained in the step (1) on a coffee bean grinder to 35 meshes to obtain ground coffee powder;
(3) conveying the ground coffee powder obtained in the step (2) to an extraction tank for extraction with water, wherein the extraction temperature is 190 ℃, the extraction pressure is 1.2MPa, the extraction time is 30min, and in the extraction process, when the mass of extracted liquid is 20% of the total mass of extracted liquid, the extracted liquid serves as aromatic liquid raw liquid (25 tons), residual water is continuously extracted, and the residual extracted liquid serves as low-aroma extract liquid (75 tons);
(4) and (3) directly conveying the aromatic liquid stock solution obtained in the step (3) to a flash tank, feeding the steam obtained by flash evaporation into a distillation tower for distillation, collecting gas generated by distillation and condensing to obtain aromatic liquid, and collecting the liquid at the bottom of the distillation tower to obtain a low-aroma liquid component, wherein the distillation is carried out at the temperature of 135 ℃ and the pressure of 0.31MPa, and the cooling substance used for condensation is water at the temperature of 10 ℃.
(5) And (3) adding the aromatic liquid obtained in the step (4) into a rotary evaporator, fractionating at 65 ℃ and under the vacuum degree of-0.07 Mpa to volatilize the aroma substances, introducing the aroma substance gas into a condenser, and condensing with ice water at 1 ℃ to obtain condensed liquid, namely the concentrated aromatic liquid, wherein the content of the aroma substances in the concentrated aromatic liquid is about 5.5%, and the residual aromatic liquid at the bottom of the evaporator is aromatic liquid residue.
(6) Mixing the low-fragrance liquid component obtained in the step (4) and the low-fragrance extraction liquid obtained in the step (3), concentrating to obtain a concentrated solution with a solid content of 45%, concentrating by adopting triple effect falling film concentration, and performing at 50 ℃ and a vacuum degree of-0.09 Mpa;
(7) combining and uniformly mixing the aromatic liquid residual liquid obtained in the step (5) and the concentrated liquid obtained in the step (6) to obtain concentrated coffee liquid;
(8) spray drying the concentrated coffee liquid obtained in the step (7) to obtain coffee dry powder;
(9) and (3) conveying the coffee dry powder obtained in the step (8) into a fluidized bed with a spray head, atomizing the concentrated aromatic liquid obtained in the step (5) by the spray head, and mixing the atomized concentrated aromatic liquid with the coffee dry powder in the fluidized bed to obtain the instant coffee, wherein the total amount of aroma substances in the instant coffee is 273.85 mu g/kg.
Comparative example 1
Taking 10 tons of Vietnam Robusta secondary coffee beans and 100 tons of drinking water, and preparing instant coffee according to the following steps:
(1) roasting the coffee beans for 700-750 s under the condition of 160-230 ℃ (roasting curve temperature variation range) to obtain roasted coffee beans;
(2) grinding the roasted coffee beans obtained in the step (1) on a coffee bean grinder to 30 meshes to obtain ground coffee powder;
(3) conveying the ground coffee powder obtained in the step (2) to an extraction tank for extraction with water, wherein the extraction temperature is 175 ℃, the extraction pressure is 1.0MPa, the extraction time is 25min, and in the extraction process, when the mass of extracted liquid is 25% of the total mass of extracted liquid, the extracted liquid serves as aromatic liquid raw liquid (25 tons), residual water is continuously extracted, and the residual extracted liquid serves as low-aroma extract liquid (75 tons);
(4) and (3) directly conveying the aromatic liquid stock solution obtained in the step (3) to a flash tank, feeding the steam obtained by flash evaporation into a distillation tower for distillation, collecting gas generated by distillation and condensing to obtain aromatic liquid, and collecting the liquid at the bottom of the distillation tower to obtain a low-aroma liquid component, wherein the distillation is carried out at the temperature of 135 ℃ and the pressure of 0.32MPa, and the cooling substance used for condensation is water at the temperature of 4 ℃.
(5) Mixing the low-fragrance liquid component obtained in the step (4) and the low-fragrance extraction liquid obtained in the step (3), and concentrating until the solid content is 45% to obtain a concentrated solution;
(6) and (3) adding the aromatic liquid obtained in the step (4) into the concentrated liquid obtained in the step (5), and then carrying out spray drying to obtain instant coffee, wherein the total amount of aroma substances in the instant coffee is 175.09 mu g/kg.
The instant coffee of example 1 and comparative example 1 were subjected to aroma analysis, and the results are shown in table 1.
Table 1 is a table comparing the total amount of aroma of the instant coffee of example 1 and comparative example 1
The instant coffee of example 1 and comparative example 1 were subjected to SPME-GC-MS analysis for aroma, the results of which are shown in FIG. 1.
The present invention is described in detail in order to make those skilled in the art understand the content and practice the invention, and the invention is not limited to the above embodiments, and all equivalent changes or modifications made according to the spirit of the invention should be covered by the scope of the invention.