阅读说明：本技术 乳酸的制备方法 (Method for producing lactic acid ) 是由 努尔·丽娜·莫哈末 于 2020-04-07 设计创作，主要内容包括：本发明涉及一种从压榨器压榨出的棕榈仁饼(PKC)制备乳酸的方法,包括：研磨/粉碎PKC,以获得磨碎的PKC；对磨碎的PKC进行灭菌；通过酶水解已灭菌的PKC,以得到PKC培养基水解产物；生长乳酸杆菌,以生产乳酸杆菌的接种物；在PKC培养基水解产物中加入酸及/或碱；利用乳酸杆菌的接种物来处理上述PKC培养基,从而产生发酵液及残余物,其中残余物为PKC固体,发酵液包含乳酸；将发酵液与PKC固体分离；将分离后的发酵液与氢氧化钙/钠混合,从而得到乳酸钙/钠的溶液；利用硫化钠/钙来处理乳酸钙/钠溶液,以产生一溶液；使溶液脱色；将脱色后的溶液酸化,以获得一溶液及一沉淀物；以及在酸化后的溶液中过滤沉淀物,其中沉淀物是脱水硫酸钙/钠,而滤液是乳酸。(The present invention relates to a method for preparing lactic acid from Palm Kernel Cake (PKC) expressed from a press, comprising: milling/pulverizing PKC to obtain a milled PKC; sterilizing the ground PKC; hydrolyzing the sterilized PKC by an enzyme to obtain a PKC medium hydrolysate; growing lactobacillus to produce an inoculum of lactobacillus; adding acid and/or alkali to the hydrolysis product of PKC culture medium; treating the PKC medium with an inoculum of lactobacillus to produce a fermentation broth and a residue, wherein the residue is a PKC solid and the fermentation broth comprises lactic acid; separating the fermentation broth from the PKC solids; mixing the separated fermentation broth with calcium hydroxide/sodium to obtain a calcium lactate/sodium solution; treating the calcium lactate/sodium solution with sodium sulfide/calcium to produce a solution; decolorizing the solution; acidifying the decolorized solution to obtain a solution and a precipitate; and filtering the precipitate in the acidified solution, wherein the precipitate is calcium/sodium sulfate dehydrate and the filtrate is lactic acid.)

1. A method for producing lactic acid from Palm Kernel Cakes (PKC), characterized in that: the method comprises the following steps:

(i) milling/grinding PKC to obtain a ground PKC having a particle size of 0.8 mm to 1.2 mm and a uniformity of dry matter content of 85% to 95%;

(ii) (ii) sterilizing the milled PKC obtained in step (i);

(iii) (iii) hydrolyzing the sterilized PKC of step (ii) by an enzyme to obtain a PKC medium hydrolysate;

(iv) growing lactobacillus to produce an inoculum of lactobacillus;

(v) (iv) adding an acid and/or a base to the PKC medium hydrolysate obtained in step (iii) to maintain the pH in the range of 5.5 to 6.5;

(vi) (vi) treating the PKC medium obtained in step (v) with the inoculum of the lactobacillus produced in step (iv) thereby producing a fermentation broth and a residue, wherein the residue is a PKC solid and the fermentation broth comprises lactic acid;

(vii) (vii) separating the fermentation broth obtained in step (vi) from the PKC solids obtained in step (vi);

(viii) (viii) mixing the fermentation broth obtained in step (vii) with calcium hydroxide or sodium hydroxide to obtain a calcium lactate solution or a sodium lactate solution;

(ix) (viii) treating the calcium lactate solution or sodium lactate solution obtained in step (viii) with sodium sulfide or calcium sulfide to produce a solution;

(x) (ix) decolorizing the solution obtained in step (ix);

(xi) (ii) acidifying the solution obtained in step (x) to obtain a solution and a precipitate; and

(xii) (xi) filtering the precipitate in the solution obtained in step (xi), wherein the precipitate is calcium sulfate dehydrate or sodium sulfate dehydrate, and a filtrate is lactic acid.

2. The method of claim 1, wherein: the PKC is expressed from oil expeller.

3. The method of claim 1, wherein: the milled PKC of step (iii) is operable to hydrolyze using the enzymes mannanase and cellulase.

4. The method of claim 1, wherein: the milled PKC of step (iii) is operable to hydrolyze over a period of 40 to 50 hours.

5. The method of claim 4, wherein: the milled PKC of step (iii) is operable to hydrolyze over a period of 48 hours.

6. The method of claim 1, wherein: the milled PKC in step (iii) is operable to hydrolyze at a temperature in a range of 50 ℃ to 60 ℃.

7. The method of claim 6, wherein: the milled PKC in step (iii) is hydro lyzed at a temperature of 60 ℃.

8. The method of claim 1, wherein: (viii) mixing the fermentation broth of step (viii) with calcium hydroxide at a pH in the range of from 9 to 10.5.

9. The method of claim 1, wherein: the fermentation broth in step (viii) is preferably mixed with calcium hydroxide at pH 10.

10. The method of claim 1, wherein: the solution in step (x) is acidified to a pH of 5.5 to 6.5.

11. The method of claim 1, wherein: the solution in step (x) is acidified to pH 6.2.

12. Lactic acid produced according to the method of any one of claims 1 to 11.

13. A Palm Kernel Cake (PKC) solid produced according to the method of any one of claims 1 to 7.

Technical Field

The present invention relates to a method for the preparation of lactic acid from Palm Kernel Cake (PKC), wherein the PKC is a PKC expressed from a press.

Background

Palm Kernel Cake (PKC) is a solid residue of oil extracted from the kernel of oil palm seeds. The palm kernel cake is widely used as a feed ingredient for animal feed. There are generally two main methods of use; high pressure screw press (i.e., expeller) or solvent-based (i.e., hexane) extraction. Especially when obtained by high pressure screw pressing, PKC is also known as palm kernel expeller (palm kernel).

PKC is used as a nutritional supplement in animal feed. The major components of PKC are proteins and polysaccharides. PKC is not widely used in poultry diets because of its high content of non-starch polysaccharides (NSP). The major multiple NSPs are mannans, especially B-mannan type hemicelluloses. The mannan polymers in PKC fibers are highly crystalline, insoluble, and do not depolymerize in the digestive tract of poultry. The presence of multiple NSPs reduces feed and nutrient conversion efficiency in monogastric animal feed.

Typically, after excretion, PKC is improved by enzymatic hydrolysis and fermentation. Mannanases are effective enzymes that can improve the nutritional value in PKC, because mannanases are able to break down the components that make up hemicellulose. Endo-3-mannase, exo-fi-mannase and B-mannosidase are the main mannases, and can be used for decomposing and transforming mannan, which is the main component of hemicellulose.

Recently, as the demand in the chemical field increases, the polymer market grows and the demand for lactic acid as a raw material in the food industry increases, lactic acid produced from bio-based resources (e.g., PKC) increases. The yield of biomass converted or broken down into valuable components (e.g., lactic acid) is higher and more effort is put on identifying alternative methods and catalytic conversion and fermentation pathways to utilize abundant but less valuable biomass or waste biomass.

Currently, most Lactic Acid Bacteria (LAB) used for Lactic Acid fermentation can effectively utilize glucose extracted from a cellulose fraction obtained by hydrolysis of biomass, mannose extracted from mannan is considered as a sugar that is not easily fermented by Lactic Acid Bacteria, and the difficulty in fermentation of mannose may be related to the stereoisomeric configuration of mannose.

To date, there is no suitable method for assimilating mannose as a main carbon source to produce lactic acid by enzymatic fermentation of PKC.

WO2015/197623 discloses an improved bioavailability of protein/amino acids in Palm Kernel Cakes (PKCs) and methods of producing improved PKCs. The improved bioavailability of the proteins/amino acids in PKC is obtained by reducing the processing temperature and/or processing time and/or pressing force of the press during palm kernel oil extraction. The modified PKC may be used as an animal feed, for example: for feeding monogastric animals, for example: poultry and pigs.

WO2014/189355 discloses a method of enzymatic Palm Kernel Cake (PKC) hydrolysis using enzymes. The hydrolysis process uses one or more enzymes that advantageously break down or degrade polysaccharides and/or protein components contained in the plant cell wall. The hydrolysis process releases residual oil and smaller sugar molecules.

US 2006/0292264a1 discloses a biological method for producing fermented Palm Kernel Cakes (PKC). By using Bacillus megaterium (Bacillus megaterium) in combination with Lactobacillus (Lactobacillus sp), it is possible to break down the mannan fibers in the original PKC, thereby increasing the nutritional value of PKC in animal feed. US 2006/0292264a1 also discloses animal feeds comprising fermented PKC, which feeds are useful for feeding monogastric animals.

To date, no prior art discloses assimilation of a solution of mannose as a major carbon source during fermentation. The present invention seeks to provide a solution for the production of lactic acid by fermentation of lactic acid bacteria together with a mannose hydrolysate. The present invention includes the use of appropriate fermentation parameter conditions and sufficient laboratory nutrients to assimilate mannose as a primary carbon source to produce lactic acid.

Disclosure of Invention

The present invention relates to a method for the preparation of lactic acid from Palm Kernel Cake (PKC), wherein the PKC is press-pressed Palm Kernel Cake (PKC). The method of preparing lactic acid from Palm Kernel Cake (PKC) comprises the steps of: (i) milling/pulverizing PKC to obtain a milled PKC; (ii) (ii) sterilizing the milled PKC obtained in step (i); (iii) (iii) hydrolyzing the sterilized PKC of step (ii) by an enzyme to obtain a PKC medium hydrolysate; (iv) growing lactobacillus to produce an inoculum of lactobacillus; (v) (iv) adding an acid and/or a base to the PKC medium hydrolysate obtained in step (iii); (vi) (vi) treating the PKC medium obtained in step (v) with the inoculum of the lactobacillus produced in step (iv) thereby producing a fermentation broth and a residue, wherein the residue is a PKC solid and the fermentation broth comprises lactic acid; (vii) (vii) separating the fermentation broth obtained in step (vi) from the PKC solids obtained in step (vi); (viii) (viii) mixing the fermentation broth obtained in step (vii) with calcium hydroxide or sodium hydroxide to obtain a calcium lactate solution or a sodium lactate solution; (ix) (viii) treating the calcium lactate solution or sodium lactate solution obtained in step (viii) with sodium sulfide or calcium sulfide to produce a solution; (x) (ix) decolorizing the solution obtained in step (ix); (xi) (ii) acidifying the solution obtained in step (x) to obtain a solution and a precipitate; and (xii) filtering the precipitate in the solution obtained in step (xi), wherein the precipitate is calcium sulfate dehydrate or sodium sulfate dehydrate, and a filtrate is lactic acid.

Other aspects, features and advantages of the present invention will become apparent to those skilled in the art upon review of the following detailed description of the preferred embodiments of the invention in conjunction with the accompanying figures.

Description of the drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the invention and, together with the description, serve to explain the principles of the invention.

Fig. 1 shows a flow diagram of a method for producing lactic acid from PKC according to the invention.

Detailed Description

Detailed descriptions of several preferred embodiments of the invention are disclosed herein. However, it is to be understood that the embodiments are merely examples of the present invention, which can be embodied in various forms. Therefore, the details disclosed herein are not to be interpreted as limiting, but merely as the basis for the claims and as a basis for teaching one skilled in the art to variously employ the present invention.

It is an object of the present invention to provide a method for the preparation of lactic acid from Palm Kernel Cake (PKC), wherein the PKC is a press expressed PKC.

It is another object of the invention to obtain lactic acid from a PKC/squeezer, which is hydrolyzed in the presence of enzymes (e.g., mannanase and cellulase) and fermented using LAB (i.e., lactobacillus).

As shown, the present invention relates to the use of Lactobacillus (LAB) for the production of lactic acid. The term "LAB" is defined in the context of the present invention to include bacteria from the genera Lactobacillus (Lactobacillus), Leuconostoc (Leuconostoc), Pediococcus (Pediococcus), Lactococcus (Lactococcus) and Streptococcus (Streptococcus), as well as Aerococcus (Aerococcus), Carnobacterium (Carnobacterium), Enterococcus (Enterococcus), Oenococcus (Oenococcus), Lactobacillus (Sporolactis), Tetragenococcus (Tetragenococcus), Vagococcus (Vagococcus) and Weissella (Weissel) all belonging to the order Lactobacillus (Lactobacillus). Preferably, the term "LAB" refers to a species of the genus lactobacillus.

Species of the genus lactobacillus may be, but are not limited to: derived from obligate homofermentative bacteria, facultative heterofermentative bacteria and/or obligate heterofermentative bacteria. Obligate homofermentative bacteria include, but are not limited to: lactobacillus rhamnosus (l.rhamnosus), lactobacillus acidophilus (l.acidophilus), lactobacillus delbrueckii (l.delbrueckii), lactobacillus helveticus (l.helveticus), and lactobacillus salivarius (l.salivarius). Facultative heterofermentative bacteria include, but are not limited to: lactobacillus casei (l.casei), lactobacillus curvatus (l.curvatus), lactobacillus plantarum (l.plantarum) and lactobacillus sake (l.sakei). Obligate heterofermentative bacteria include, but are not limited to: lactobacillus brevis (l.brevis), lactobacillus buchneri (l.buchneri), lactobacillus fermentum (l.fermentum) and lactobacillus reuteri (l.reuteri). In the present invention, obligate homofermentative bacteria, in particular Lactobacillus rhamnosus, are used.

Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

The present invention relates to a method for the preparation of lactic acid from Palm Kernel Cake (PKC), wherein the PKC is expressed from a squeezer, in particular the method drives a method for the production of lactic acid by fermentation of mannose hydrolysate with lactobacillus. Preferably, the present invention relates to the use of one suitable fermentation parameter condition and sufficient nutrients for the LAB assimilation of mannose as a main carbon source and the production of lactic acid.

A method for producing lactic acid from Palm Kernel Cake (PKC) expressed from a press, comprising:

(i) milling/pulverizing PKC to obtain a milled PKC;

(ii) (ii) sterilizing the milled PKC obtained in step (i);

(iii) (iii) hydrolyzing the sterilized PKC of step (ii) by an enzyme to obtain a PKC medium hydrolysate;

(iv) growing lactobacillus to produce an inoculum of lactobacillus;

(v) (iv) adding an acid and/or a base to the PKC medium hydrolysate obtained in step (iii);

(vi) (vi) treating the PKC medium obtained in step (v) with the inoculum of the lactobacillus produced in step (iv) thereby producing a fermentation broth and a residue, wherein the residue is a PKC solid and the fermentation broth comprises lactic acid;

(vii) (vii) separating the fermentation broth obtained in step (vi) from the PKC solids obtained in step (vi);

(viii) (viii) mixing the fermentation broth obtained in step (vii) with calcium hydroxide or sodium hydroxide to obtain a calcium lactate solution or a sodium lactate solution;

(ix) (viii) treating the calcium lactate solution or sodium lactate solution obtained in step (viii) with sodium sulfide or calcium sulfide to produce a solution;

(x) (ix) decolorizing the solution obtained in step (ix);

(xi) (ii) acidifying the solution obtained in step (x) to obtain a solution and a precipitate; and

(xii) (xi) filtering the precipitate in the solution obtained in step (xi), wherein the precipitate is calcium sulfate dehydrate or sodium sulfate dehydrate, and a filtrate is lactic acid.

Details of the method are described below, which are not limited to the example used.

Referring to the drawings, fig. 1 shows a flow chart of a method for producing lactic acid from PKC. The method comprises the following steps: a first step of milling/grinding of PKC to obtain a ground PKC having a particle size of 0.8 mm to 1.2 mm, preferably 1.0 mm, and a uniformity of dry matter content of 85% to 95%, preferably 90%. The PKC may be obtained from any commercially available PKC vendor, such as, but not limited to: owner of oil palm plantation and/or factory.

The milled PKC was sterilized. The sterilization method comprises the following steps: moist heat/steam sterilization. The moist heat sterilization method comprises the following steps: autoclaving or steam treatment at 115 to 125 ℃ for 15 to 25 minutes. The sterilized PKC is hydrolyzed by enzymes (e.g., mannanase and cellulase) for a time period of 40 hours to 50 hours, preferably 48 hours, and at a temperature of 50 ℃ to 60 ℃, preferably 60 ℃. Enzymatic hydrolysis is performed in a stirred tank bioreactor to produce a PKC medium hydrolysate. Adding an alkali metal hydroxide and/or acidic calcium carbonate together to the PKC medium hydrolysate to maintain the pH of the PKC medium hydrolysate in the range of 5.5 to 6.5, preferably at a pH of 6.2.

Meanwhile, the lactobacillus is grown in a commercially available MRS broth for 36 to 48 hours, preferably 48 hours, and at a temperature of 35 to 45 ℃, preferably 45 ℃. The grown lactobacilli were used as inoculum in a subsequent step.

Thereafter, the PKC is treated with an inoculum of lactobacillus for 5 to 10 days, preferably 10 days, to produce a fermentation broth and a residue. The fermentation is a submerged fermentation (submerged fermentation) and is carried out in a closed vessel controlled under anaerobic conditions at a temperature of between 30 ℃ and 40 ℃, at a pH of between 5 and 7, and having, for example: yeast extract, peptone and salt.

The fermentation product is then a fermentation broth and a residue, wherein the residue is a PKC solid, and wherein the fermentation broth comprises lactic acid. Separating the PKC solid from lactic acid by filtration. The filtration method is simple filtration or gravity filtration, vacuum filtration, but is not limited to the above filtration method.

The separated lactic acid containing fermentation broth is then mixed with calcium hydroxide or sodium hydroxide at a pH of 9 to 10.5 (preferably pH 10) to produce a mixture. Allowing the mixture to settle to produce a solution of calcium lactate or a solution of sodium lactate. The calcium lactate solution or the sodium lactate solution is treated with sodium sulfide or calcium sulfide to produce a solution. Thereafter, the solution is decolorized with activated carbon and acidified in a range of pH 5.5 to 6.5 to obtain a solution and a precipitate, preferably pH 6.2.

Finally, the precipitate is filtered from the solution using a simple filtration method. The precipitate is calcium sulfate dehydrate or sodium sulfate hydrate, and the filtrate is lactic acid.

The invention is illustrated in a non-limiting manner in the following examples.

Method for producing lactic acid from Palm Kernel Cake (PKC):

(i) milling/grinding PKC to obtain a ground PKC having a particle size of 0.8 mm to 1.2 mm, preferably 1.0 mm, and a uniformity of dry matter content of 85% to 95%, preferably 90%;

(ii) (ii) sterilizing the ground PKC obtained in step (i) at 115 to 125 ℃ for 15 to 25 minutes;

(iii) (iii) hydrolyzing the sterilized PKC obtained from step (ii) by enzymes (e.g., mannanase and cellulase) in a stirred tank bioreactor at a temperature in a range of 50 ℃ to 60 ℃ (preferably 60 ℃) to produce a PKC medium hydrolysate, said hydrolysis being for a time period of 40 hours to 50 hours, preferably 48 hours;

(iv) culturing lactobacillus in MRS medium for 36 to 48 hours (preferably 48 hours) and producing an inoculum of lactobacillus in a range of 35 ℃ to 45 ℃ (preferably 45 ℃);

(v) (iv) adding sodium hydroxide and/or calcium carbonate to the PKC medium hydrolysate obtained in step (iii) to maintain the pH in the range of 5.5 to 6.5, preferably at a pH of 6.2;

(vi) (vi) treating the PKC medium obtained in step (v) with the inoculum of the lactobacillus produced in step (iv) to produce a fermentation broth and a residue, the treatment time being from 5 days to 10 days (preferably 10 days), wherein the residue is a PKC solid and the fermentation broth comprises lactic acid;

(vii) (vii) separating the fermentation broth obtained in step (vi) from the PKC solids obtained in step (vi) and discarding the PKC solids and using the fermentation broth for subsequent steps;

(viii) (viii) mixing the fermentation broth obtained in step (vii) with calcium hydroxide or sodium hydroxide at a pH in the range of 9 to 10.5 (preferably pH 10) to obtain a calcium lactate solution or a sodium lactate solution;

(ix) (viii) treating the calcium lactate solution or sodium lactate solution obtained in step (viii) with sodium sulfide or calcium sulfide to produce a solution;

(x) (ix) decolorizing the solution obtained in step (ix) with activated carbon;

(xi) (ii) acidifying the solution obtained in step (x) to a pH value in the range of 5.5 to 6.5 (preferably a pH value of 6.2) to obtain a solution and a precipitate; and

(xii) (xi) filtering the precipitate in the solution obtained in step (xi), wherein the precipitate is calcium sulfate dehydrate or sodium sulfate dehydrate, and a filtrate is lactic acid.

The method of the present invention provides a solution for a method of assimilating mannose as a main carbon source for the production of lactic acid by enzymatic PKC fermentation. The process of the invention is also more cost effective because the hydrolysis and fermentation processes are carried out simultaneously in the same fermentation vessel.

Further, the method of the present invention provides a solution that utilizes mannose, which is considered to be a sugar that is not readily fermented by lactobacillus to produce lactic acid. Generally, the enzymatic hydrolysis of the present invention facilitates the release of mannose in a concentration of 6 to 10% by volume for the utilization by lactobacilli.

This method of producing lactic acid from biomass by a fermentation pathway through the use of enzymatic hydrolysis is a sustainable process and it utilizes abundant and less valuable biomass or waste biomass. Thus, the method will provide an opportunity for providing an accelerated demand for lactic acid in the future.

Furthermore, the present invention is commercially valuable and can be readily applied by manufacturers to the production of lactic acid from PKC. Furthermore, this is a core technology in which the present invention can be applied to fields other than lactic acid production, such as: PKC may be used as a supplement to high energy, high fiber feed for ruminants.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise.

The terms "comprises," "comprising," "including," and "having," are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude or add to the possibility of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The method steps, processes, and operations described herein are not to be construed as necessarily performed in the order discussed or illustrated, unless expressly indicated as an order of performance otherwise. It should also be understood that additional or alternative steps may be employed. The use of "at least" or "at least one" means that one or more elements are suggested for use, as the use of the elements in one of the various embodiments may be used to achieve one or more desired purposes or results.

While the foregoing is directed to various embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the appended claims. The invention is not limited to the embodiments, descriptions or examples described herein, but includes the contents that enable one of ordinary skill in the art to make and use the invention in connection with the information and knowledge available to those of ordinary skill in the art.