阅读说明：本技术 从谷物中同时生产乳酸和醇或沼气的方法 (Method for simultaneously producing lactic acid and alcohol or biogas from grains ) 是由 弗里德里克·范-甘思贝格 菲利普·科扎克 于 2018-04-18 设计创作，主要内容包括：描述了从必须在干燥条件下执行的谷物、更特别是玉米的碾磨开始的连续生产乳酸(第一发酵产物)和选自由醇和沼气组成的组的第二发酵产物的方法。在该方法的上下文中,从碾磨中回收主要流和难以发酵的废物流；这两种流分开但同时处理,以便一方面通过发酵产生乳酸而另一方面产生醇和/或沼气。(A process is described for the continuous production of lactic acid (first fermentation product) and a second fermentation product selected from the group consisting of alcohol and biogas starting from the milling of cereals, more particularly corn, which must be carried out under dry conditions. In the context of this process, a main stream and a waste stream that is difficult to ferment are recovered from the mill; these two streams are treated separately but simultaneously in order to produce lactic acid by fermentation on the one hand and alcohol and/or biogas on the other hand.)

1. A continuous process for the simultaneous production of lactic acid and a second fermentation product starting from cereals, comprising the stages consisting in:

dry milling the corn kernels and/or the corn cobs (20) in a mill (100) to form a millbase;

recovering the millbase (131) and mixing the millbase with a water stream in a mixer (102) to produce a slurry (103);

subjecting the slurry (103) to saccharification (104) in a reactor and producing a crude dextrose stream (105);

-in separators (106 and 107), the crude dextrose stream (105) is divided into two streams, the first stream comprising a liquid stream (108) and the second stream comprising a solid fraction (21);

removing the oil milled and present in the liquid stream (108) for subsequent treatment and recovering a purified dextrose stream (110);

wherein:

-subjecting the purified dextrose stream (110) to a selective separation of sugars (111) and recovering a purified stream (116), then subjecting said purified stream to a fermentation (118) in the presence of a microorganism (26) suitable for producing lactic acid (28);

recovering the solid dextrose stream (21) containing products difficult to ferment via line (121) and a stream rich in oligosaccharides (29) via line (112) to hydrolyze them under hydrolysis conditions in reactor (113) and convert them into a fermentable dextrose stream (114); and

subjecting the fermentable dextrose stream (114) to fermentation in a fermentor (120) to produce a second fermentation product (101).

2. The method of claim 1, wherein selectively separating the sugars (111) from the purified dextrose stream (110) is performed by chromatography.

3. The method of claim 1, wherein hydrolysis is performed in the reactor (113) in the presence of a strong acid at a temperature between 140 ℃ and 180 ℃ for a period of 30 minutes to 2 hours.

4. The method of claim 1, wherein the second fermentation product (101) is selected from the group consisting of alcohol and/or biogas.

5. The method of claim 4, wherein the alcohol is ethanol or butanol.

6. A system for the simultaneous continuous production of two dextrose streams starting from dry milling of grains, the system comprising:

a grain mill (100) equipped for dry milling,

a mixing vessel (102) for preparing a slurry (103) resulting from mixing the millbase (131) with a water stream,

a saccharification reactor (104),

a separator (106) for producing two dextrose streams, one stream (108) comprising liquid material and the other stream (21) comprising solid material,

a separator (109) for removing oil from the stream (108) and recovering a purified dextrose stream (110),

a system for chromatographic separation to remove oligosaccharides from the purified dextrose stream (110),

a fermenter for producing lactic acid (28), and

a fermenter (120) for producing alcohol or biogas.

Technical Field

The present invention relates to a continuous process for the simultaneous production of lactic acid (as a first fermentation product) and a second fermentation product starting from cereals, in particular from corn kernels.

The process of the present invention comprises several stages, the main of which is dry milling of the corn cobs (which will constitute the primary stream), separating the difficult to ferment wastes and other products from the mill (which will constitute the secondary stream), and processing these difficult to ferment wastes and other products to produce alcohol and/or biogas, while separately processing the initial mill product (purified from the difficult to ferment wastes and other products) for subsequent fermentation in a fermentor to produce lactic acid.

It is another object of the present process to maximize the economic upgrading of corn kernels.

Background

Following the liberalization of the sugar market, there is also an entry barrier introduced at the european level, and a significant trend towards the price of raw materials used in the production of commercial products such as biofuels (e.g. bioethanol), citric acid, succinic acid, lactic acid, etc. from biochemical compounds has become apparent. It is therefore imperative for these industrial enterprises to optimize their supply in order to obtain large quantities of raw materials available, to make biotechnological processes feasible at competitive costs and of sufficient quality without the need for major adjustments to pre-existing production units. In this case, several raw materials such as corn, wheat, barley, sorghum, rice, rye or oats can be envisaged, more particularly corn may advantageously respond to several of these criteria.

In the prior art relating to these grain treatment processes, it is known that the corn cobs contained in the grain can be subjected to either wet milling or dry milling, and dry milling is generally simpler and less expensive in two operating routes.

It is also common practice to separate the waste comprising fibres, germ and other products that are difficult to ferment from the initial stream consisting of directly fermentable products at the end of the milling or later in the process.

This is also described in patent EP 3121258 which mentions the need to separate undesirable components as well as components that are difficult to ferment prior to fermentation to produce biofuels, but also suggests that not being the separated fraction is annoying because of the large capital costs required for its handling, which makes the process unsatisfactory for economic upgrade.

Currently, there is no simple and relatively inexpensive method to produce lactic acid (as a first fermentation product) and a second fermentation product such as alcohol and/or biogas from grain.

In fact, lactic acid is a product that finds new applications every day, in particular as food preservative, but also in synthetic or biodegradable polymers for solvents. Furthermore, after upgrading in the form of ethanol, the residual fraction of the secondary stream can also be upgraded in the preparation of livestock feed or in other forms of application, such as biogas.

It is therefore evident that there is a real need for a simple and relatively inexpensive process for the production of lactic acid and a second fermentation product starting from cereals, and in particular from corn kernels or cobs (corn kernel cobs).

Object of the Invention

The object of the process of the invention is to make it possible to simultaneously produce lactic acid as a first fermentation product and a second fermentation product starting from a cereal, such as corn.

The object of the process of the invention is to make it possible to simultaneously produce lactic acid and an alcohol such as ethanol or butanol starting from a grain such as a corn kernel or a cob.

The object of the method of the invention is to make it possible to produce lactic acid and biogas simultaneously starting from grains such as corn kernels or cobs.

Another object of the process of the invention is to upgrade the fractions containing undesired components and/or components that are difficult to ferment in order to convert them into alcohol or biogas.

It is another object of the present invention to maximize the economic upgrade of the processing of grains, particularly corn kernels or corn cobs.

The applicant company has now found that the above mentioned objects can be achieved by implementing a method comprising the following stages:

dry milling the corn kernels and/or corn cobs 20 in a mill 100;

recovering the stream 131 resulting from the milling and mixing it with a stream of water in the mixer 102 (i.e. performing a liquefaction stage) to produce a slurry 103;

subjecting the slurry 103 to a saccharification stage 104 in a reactor and producing a crude dextrose stream 105;

the crude dextrose stream 105 is divided into two streams, the first stream comprising a liquid dextrose stream 108 and the second dextrose stream comprising a solid fraction 21 consisting of the two streams produced by two successive separation stages (carried out by using two separators 106 and 107 in sequence) and finally forming stream 21;

the oil milled and present in the liquid dextrose stream 108 is separated in a separator 109 and, on the one hand, recovered for subsequent processing (such as an oil refining stage 130) and, on the other hand, a purified dextrose stream 110;

wherein:

subjecting the purified dextrose stream 110 to a selective separation stage 111 of sugars and recovering a purified dextrose stream 116, which is purer than stream 110, then subjecting the dextrose stream to a fermentation 118 and, on the other hand, recovering an oligosaccharide-rich stream 29;

subjecting the purified dextrose stream 116 to fermentation 118 in the presence of microorganisms 26 suitable for producing lactic acid 28;

a solid dextrose stream 21 containing products difficult to ferment resulting from two successive separation stages (carried out by using two separators 106 and 107 in sequence) is recovered via line 121 and an oligosaccharide-rich stream 29 resulting from the selective separation 111 of sugars is recovered via line 112 to hydrolyze them and convert them into a fermentable dextrose stream 114 in reactor 113 under hydrolysis conditions;

subjecting the fermentable dextrose stream 114 to fermentation in a fermentor 120 to produce a second fermentation product 101, preferably selected from the group consisting of ethanol, butanol and/or biogas.

It is to be clearly understood that corn on the one hand and wheat, barley, sorghum, rye, rice, oats or other similar products on the other hand are understood as cereals.

Main characteristic elements of the invention

The process of the present invention comprises dry milling the grain 20 (a suitable example of which is corn kernels and/or corn cobs) in a suitable mill 100 to produce two separate streams of sugar or dextrose simultaneously.

The milling must be carried out by a dry route rather than by a wet route, as is also the case with processes of the glucose industry in general.

After dry milling of the corn kernels and/or the corn cobs 20 in the mill 100, the millbase 131 is recovered and mixed with a water stream in a mixer 102, where a liquefaction stage (hydrolysis of starch to produce maltodextrins and oligosaccharides) is performed to form a slurry 103, followed by a saccharification stage 104 (conversion of complex sugars to simple sugars such as glucose).

After the saccharification stage 104, the dextrose stream is divided into two parts, a liquid 108 constituting the main stream and containing a dextrose stream with a dextrose content DE (dextrose equivalent) of about 80%, and a second solid part 21 consisting of a secondary stream containing components that are difficult to ferment.

This secondary flow 21 comprises in particular fibrous elements, bacteria and proteins.

According to one embodiment of the process of the present invention, primary stream 108 is then treated to remove oil, produced by milling of the corn kernels, via stream 25; after this first purification, the main stream 110 is subjected to a filtration stage 115 and the oligosaccharides are separated therefrom via stream 29 to obtain a relatively pure dextrose stream 116 (> 95%, indeed even > 99%) to undergo fermentation 118 in the presence of microorganisms 26 of the bacterial, yeast or mold type to produce lactic acid 28.

Still according to one embodiment of the process of the invention, the secondary stream 21 is recovered and the oligosaccharides 29 recovered from the primary stream 108 are added thereto to send it to the stage of hydrolysis in the presence of a strong acid in the reactor 113. The resulting stream 114 is directed to a second fermentor 120 to convert the second dextrose stream to an alcohol to produce bioethanol or butanol, and/or to biogas.

Drawings

The method of the invention is also described by the following figures:

fig. 1 shows a schematic of (one embodiment) of the process of the present invention, starting with dry milling of a corn cob 20 in a mill 100 to produce two dextrose streams, one dextrose stream intended to produce lactic acid 28 as a first fermentation product and the other dextrose stream intended to produce a second fermentation product 101 such as an alcohol or biogas.

Detailed Description

Referring to fig. 1, a description is given of a system for dry milling corn cobs 20 in a mill 100 to ultimately produce two dextrose (flow or) streams, as will be described below.

After dry milling by means of the mill 100, the corn flour thus obtained and the remaining part 131 of the millbase containing fibres, germs and hardly fermentable components are then introduced into the mixer 102, where they are mixed with a fresh water stream and a circulating water stream from a subsequent stage of the process, to which mixer 102 also enzymes 27 such as α -amylase can be added, and the obtained slurry 103 can be heated, if necessary, to a temperature between 60 ℃ and 100 ℃ for a period of 30 to 120 minutes, whereby the slurry 103 is obtained.

The slurry 103, which comprises corn kernels, germ, fiber, protein, and oil resulting from milling of the corn kernels, is then sent to a saccharification stage 104. The dry solids content of the slurry 103 represents approximately from 25% to 40% by weight.

The saccharification stage 104 produces a crude dextrose stream 105.

According to one embodiment of the method of the present invention, saccharification reaction 104 is performed in two stages.

During the first stage, the pH is first adjusted to between 3.5 and 7.0 while maintaining the temperature between ambient and 100 ℃ for a period of 1 to 6 hours to convert insoluble starch to dextrose A catalyst such as α -amylase may also be added at a rate of 0.01 to 0.1% by weight to perform the reaction.

During the second stage, the pH is readjusted to a value between 4.0 and 5.0, while heating at a temperature ranging from ambient temperature to 180 ℃ for a period of 2 to 5 hours, still in order to complete the conversion of insoluble starch to dextrose, at this stage a catalyst such as glucoamylase or α -amylase may also be added in a proportion of 0.01% to 0.2% by weight.

The dextrose stream 105 thus recovered has a dextrose content of about 90 DE.

After the saccharification stage 104, a first separation is performed in the crude dextrose stream by passing the crude dextrose stream 105 through a filter 106, which separates a liquid portion 108 from a solid portion 21; the solid fraction includes fiber, germ and meal as well as difficult to ferment components.

This solid fraction 21 is then sent via line 121 to reactor 113 for treatment to convert it to fermentable dextrose (stream or) stream 114.

In addition, the liquid fraction 108 produced by the separator is sent to another separator 109 to remove the oil originating from the milling of the corn kernels; this oil separation is performed by methods well known to those skilled in the art.

The extracted oil is recovered via line 117 to be purified and used for other purposes.

The substantially oil-free dextrose stream 110 is optionally filtered 115 again to remove any solid particles and then sent to a reactor to remove the oligosaccharides 29 and obtain a dextrose stream 116 that is as pure as possible and then subjected to fermentation 118.

According to a preferred embodiment of the process of the present invention, the purity of the dextrose stream 116 is preferably increased to a DX content of 99% in order to have an easy fermentation, high productivity and a more manageable impurity profile in the production of lactic acid 28. In this case, the dextrose stream 110 will be subjected to a selective separation stage of the sugars 111, possibly consisting of chromatography (stage) plus microfiltration and/or desalination (no particles are able to enter chromatography). A concentration stage may also be performed prior to chromatography to enable chromatography to be performed under optimal conditions.

The oligosaccharides 29 thus recovered are sent through line 112 to a reactor 113 where they are mixed with the stream 21 coming from line 121, in order to be converted therein into a stream of fermentable dextrose 114.

After the final separation 111, the resulting dextrose stream 116 is sent to a fermentor where it is subjected to a fermentation stage 118 to which is added microorganisms 26 such as Lactobacillus (Lactobacillus), Bacillus (Bacillus), Bacillus (Sporolactobacillus) that produce lactic acid 28 under well known operating conditions for performing this operation.

At the same time, the solid fraction 21 and the oligosaccharides 29 recovered from the successive separation stages (by using the two separators 106 and 107 in sequence) (via the line 121) are sent to the mixing reactor 113 through the line 112, and the mixture is subjected to hydrolysis to make it fermentable. The hydrolysis is carried out with a large amount of water, typically 50% to 80% of the mixture, at a temperature between 140 ℃ and 180 ℃, typically in the presence of a strong acid, for a period of time of 15 to 120 minutes. After the hydrolysis reaction, a fermentable dextrose stream 114 is obtained, which is sent via a conduit to a fermentor 120 to which microorganisms 26 are added which convert the second dextrose (stream or) stream to alcohols such as butanol or ethanol (to be used as bioethanol) and/or biogas.

For the production of alcohols, possible microorganisms are yeasts such as Saccharomyces (Saccharomyces), Schizosaccharomyces (Schizosaccharomyces), Zymomonas mobilis, or bacteria such as Clostridium (Clostridium), Escherichia coli (Escherichia coli), Pseudomonas putida (Pseudomonas putida), etc.

In order to produce two dextrose streams simultaneously and continuously starting from a dry grain mill, the system used in the present invention comprises:

a grain mill 100 equipped to perform dry milling,

a mixing vessel 102 (or mixer) for preparing a slurry 103 resulting from mixing the millbase 131 with a water stream,

a saccharification reactor (a reactor for performing a saccharification stage) 104,

a separating filter 106 for producing two dextrose streams, one stream 108 containing liquid substances, the other stream 21 containing solid substances, and the two dextrose streams being produced by two successive separation stages (by using two separators 106 and 107 in sequence),

a separator 109 for removing oil from the dextrose stream 108 and recovering a purified dextrose stream 110,

a system for separation by chromatography to remove oligosaccharides 29 from a purified dextrose stream 110 (purified dextrose stream 110 resulting from the separation performed in separator 109 or, in other words, purified dextrose stream 110 recovered from the stage of separation of the oil);

a fermenter for producing lactic acid 28 (for carrying out the fermentation stage 118), and

a fermenter 120 for producing alcohol or biogas.

The process of the present invention is also illustrated by the following example, which is in no way intended to be limiting.