阅读说明：本技术 一种麦芽四糖含量高的低聚麦芽糖浆的制备工艺 (Preparation process of oligomeric maltose syrup with high maltotetraose content ) 是由 于秋生 何剑飞 於慧利 韩粉丽 于 2020-04-08 设计创作，主要内容包括：本发明公开了一种麦芽四糖含量高的低聚麦芽糖浆的制备工艺,包括,将淀粉加水调成淀粉浆,调节所述淀粉浆pH为5.8～6.0；将耐高温α-淀粉酶加入所述淀粉浆,经一次喷射液化、层流罐保温、二次喷射液化制得液化液；将所述液化液迅速降温至55～65℃时先后加入普鲁兰酶和麦芽四糖酶进行糖化反应,糖化反应5～18h后,得到反应液；将所述反应液进行活性炭脱色、离子交换、浓缩,即得本发明的低聚麦芽糖浆。本发明在液化结束后采用闪蒸换热器迅速降温至糖化温度,避免降温过程中淀粉老化和回生的问题,并采用先加入普鲁兰酶再加入麦芽四糖酶的两步加酶法进行糖化,提高麦芽四糖转化率,简化工艺流程,制备得到麦芽四糖含量≥65％的低聚麦芽糖浆。(The invention discloses a preparation process of oligomeric maltose syrup with high maltotetraose content, which comprises the steps of adding water into starch to prepare starch slurry, and adjusting the pH value of the starch slurry to 5.8-6.0; adding high-temperature-resistant alpha-amylase into the starch slurry, and performing primary spraying liquefaction, laminar flow tank heat preservation and secondary spraying liquefaction to obtain liquefied liquid; rapidly cooling the liquefied liquid to 55-65 ℃, adding pullulanase and maltotetraose in sequence for saccharification reaction, and obtaining reaction liquid after saccharification reaction for 5-18 h; and (3) decoloring the reaction solution by using activated carbon, carrying out ion exchange and concentrating to obtain the oligomeric maltose syrup. According to the invention, after liquefaction is finished, the flash evaporation heat exchanger is adopted to rapidly cool to the saccharification temperature, so that the problems of starch aging and retrogradation in the cooling process are avoided, and the two-step enzyme method of firstly adding pullulanase and then adding maltotetraose is adopted to carry out saccharification, so that the conversion rate of maltotetraose is improved, the process flow is simplified, and the prepared oligomeric maltose syrup with the maltotetraose content of more than or equal to 65 percent is obtained.)

1. A preparation process of oligomeric maltose syrup with high maltotetraose content is characterized by comprising the following steps: comprises the steps of (a) preparing a mixture of a plurality of raw materials,

adding water into starch to prepare starch slurry, and adjusting the pH of the starch slurry to 5.8-6.0;

adding high-temperature-resistant alpha-amylase into the starch slurry, and performing primary spraying liquefaction, laminar flow tank heat preservation and secondary spraying liquefaction to obtain liquefied liquid;

rapidly cooling the liquefied liquid to 55-65 ℃, adding pullulanase and maltotetraose in sequence for saccharification reaction, and obtaining reaction liquid after saccharification reaction for 5-18 h;

and (3) decoloring the reaction solution by using activated carbon, carrying out ion exchange and concentrating to obtain the oligomeric maltose syrup.

2. The process for producing a maltotetraose-rich malt oligosaccharide syrup according to claim 1, wherein: the starch is one or more of corn starch, rice starch, sweet potato starch, wheat starch, cassava starch and sorghum starch.

3. The process for producing maltotetraose-rich malto-oligosaccharide syrup according to claim 1 or 2, wherein: the mass concentration of dry substances in the starch slurry is 13-21.5%.

4. The process for producing a maltotetraose-rich malt oligosaccharide syrup according to claim 1, wherein: the high-temperature resistant alpha-amylase is in a liquid dosage form, and the addition amount of the high-temperature resistant alpha-amylase is 0.01-0.045L/ton of starch.

5. The process for producing a maltotetraose-rich malt oligosaccharide syrup according to claim 1, wherein: and performing primary spraying liquefaction at 105-115 ℃ for 10-15 min.

6. The process for producing a maltotetraose-rich malt oligosaccharide syrup according to claim 5, wherein: and performing secondary injection liquefaction at the temperature of 120-135 ℃ for 5-10 min.

7. The process for producing a maltotetraose-rich maltotetraose oligosaccharide syrup according to claim 1, 5 or 6, wherein: and the rapid cooling step is to rapidly cool the feed liquid to 55-65 ℃ by adopting a flash evaporation heat exchanger.

8. The process for producing a maltotetraose-rich malt oligosaccharide syrup according to claim 1, wherein: adding pullulanase and maltotetraose in sequence, namely adding pullulanase to react for 1-2 h, and then adding maltotetraose to carry out saccharification reaction.

9. The process for producing maltotetraose-rich maltooligosaccharide syrup according to claim 1 or 8, wherein: the pullulanase is in a liquid dosage form, and the addition amount of the pullulanase is 0.5-1.5L/ton of starch; the maltotetraose is in a liquid dosage form, and the addition amount of the maltotetraose is 0.5-1.5L/ton of starch.

10. The process for producing a maltotetraose-rich maltooligosaccharide syrup according to claim 9, wherein: the enzyme activity of the maltase is 9 multiplied by 10⁵～2×10⁶U/L。

Technical Field

The invention belongs to the technical field of starch sugar preparation, and particularly relates to a preparation process of oligomeric maltose syrup with high maltotetraose content.

Background

The oligosaccharide integrates nutrition, health care and food therapy, is widely applied to the fields of food, health care products, beverages, medical treatment, feed additives and the like, and is known as a future-type new-generation functional food. The oligosaccharides currently produced in the largest and most widely used quantities are mainly derived from starch and are commonly referred to as malto-oligosaccharides. The maltotetraose is a glucose tetramer formed by connecting 4 alpha-D glucose groups by alpha-1, 4 glycosidic bonds, is a novel functional maltooligosaccharide, has the characteristics of low sweetness, high viscosity, good moisture retention, easy digestion and absorption, low osmotic pressure and the like, inhibits intestinal putrefactive bacteria, keeps intestinal health, and promotes the human body to resist Ca²⁺Absorption and the like, and is mainly applied to the fields of food and medical treatment. Although the first research on maltotetraose has been conducted in countries such as japan, and some results have been obtained, the content of maltotetraose in products marketed in japan is only about 50%, and the requirement for adding high-end products cannot be met.

Disclosure of Invention

This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.

The present invention has been made keeping in mind the above and/or other problems occurring in the prior art.

Therefore, the invention aims to overcome the defects in the prior art and provide the preparation process of the oligomeric maltose syrup with high maltotetraose content, the invention only needs one-step pH regulation and control, has short saccharification time, can ensure that the maltotetraose content in the prepared oligomeric maltose syrup can reach more than 65 percent (accounting for dry basis), and has simple process and easy operation.

In order to solve the technical problems, the invention provides the following technical scheme: a process for preparing a high maltotetraose content malto-oligosaccharide syrup comprises,

adding water into starch to prepare starch slurry, and adjusting the pH of the starch slurry to 5.8-6.0;

adding high-temperature-resistant alpha-amylase into the starch slurry, and performing primary spraying liquefaction, laminar flow tank heat preservation and secondary spraying liquefaction to obtain liquefied liquid;

rapidly cooling the liquefied liquid to 55-65 ℃, adding pullulanase and maltotetraose in sequence for saccharification reaction, and obtaining reaction liquid after saccharification reaction for 5-18 h;

and (3) decoloring the reaction solution by using activated carbon, carrying out ion exchange and concentrating to obtain the oligomeric maltose syrup.

As a preferable aspect of the present invention, wherein: the starch is one or more of corn starch, rice starch, sweet potato starch, wheat starch, cassava starch and sorghum starch.

As a preferable aspect of the present invention, wherein: the mass concentration of dry substances in the starch slurry is 13-21.5%.

As a preferable aspect of the present invention, wherein: the high-temperature resistant alpha-amylase is in a liquid dosage form, and the addition amount of the high-temperature resistant alpha-amylase is 0.01-0.045L/ton of starch.

As a preferable aspect of the present invention, wherein: and performing primary spraying liquefaction at 105-115 ℃ for 10-15 min.

As a preferable aspect of the present invention, wherein: and the laminar flow tank is insulated, and the insulation time is 75-85 min.

As a preferable aspect of the present invention, wherein: and performing secondary injection liquefaction at the temperature of 120-135 ℃ for 5-10 min.

As a preferable aspect of the present invention, wherein: and the rapid cooling step is to rapidly cool the feed liquid to 55-65 ℃ by adopting a flash evaporation heat exchanger.

As a preferable aspect of the present invention, wherein: adding pullulanase and maltotetraose in sequence, namely adding pullulanase to react for 1-2 h, and then adding maltotetraose to carry out saccharification reaction.

As a preferable aspect of the present invention, wherein: the pullulanase is in a liquid dosage form, and the addition amount of the pullulanase is 0.5-1.5L/ton of starch; the maltotetraose is in a liquid dosage form, and the addition amount of the maltotetraose is 0.5-1.5L/ton of starch.

As a preferable aspect of the present invention, wherein: the enzyme activity of the maltase is 9 multiplied by 10⁵～2×10⁶U/L。

As a preferable aspect of the present invention, wherein: the maltase is prepared by fermenting 250g/L of soybean meal amino acid hydrolysate, 20g/L of peptone, 30g/L of glucose, 10g/L of glycerol and 10g/L of sodium glutamate for 48 hours by using recombinant bacillus subtilis as a strain.

As a preferable aspect of the present invention, wherein: the oligomeric maltose syrup can be dried to obtain oligomeric maltose powder with maltotetraose content more than or equal to 65% (on a dry basis).

The invention has the beneficial effects that:

(1) according to the invention, the DE value of the liquefied solution is controlled by controlling the concentration of the starch slurry and the addition amount of the high-temperature resistant alpha-amylase, so that a lower DE value is obtained, the chance of generating oligosaccharides with odd polymerization degrees is less, and the improvement of the content of maltotetraose in a final product is facilitated.

(2) The invention adopts the flash evaporation heat exchanger to rapidly cool after two times of injection liquefaction, can obviously reduce the aging and regeneration of the starch dextrin in the cooling process, can not obviously change the DE value of the feed liquid, and improves the conversion rate of the maltotetraose.

(3) In the process, the pH value is not required to be adjusted in other process steps except for the adjustment of the pH value required by starch size mixing, so that the consumption of alkali is saved, the existence of a large amount of ions is avoided, the pressure of the subsequent sugar liquid ion exchange link is reduced, the process operation is simplified, and the production cost is reduced.

(4) The maltase is a crude enzyme liquid product after direct fermentation, and compared with refined maltase sold on the market, the maltase complex enzyme group disclosed by the invention has a synergistic effect and a feedback regulation effect, and a product catalyzed by the first enzyme in the complex enzyme is directly catalyzed by the next enzyme, so that the metabolic speed and the whole metabolic pathway can be quickly regulated, unnecessary substrate consumption is reduced, and the saccharification efficiency is obviously improved.

(5) In the invention, pullulanase is added into a reaction substrate in a saccharification reaction stage, amylopectin is cut to form straight-chain dextrin with smaller molecular weight, and the maltotetraose enzyme is added after the reaction is carried out for 1-2 h, so that the conversion rate of maltotetraose is improved.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, specific embodiments thereof are described in detail below with reference to examples of the specification.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

The raw materials and drugs mentioned in the examples are all common commercial products unless otherwise specified.

The biological enzymes involved in the examples are all liquid dosage forms, wherein, the enzyme activity of the high temperature resistant alpha-amylase is 2 x 10⁷～3×10⁷U/L, the enzyme activity of maltetraose is 9 multiplied by 10⁵～2×10⁶U/L, the enzyme activity of pullulanase is 1 multiplied by 10⁶～2×10⁶U/L。

High temperature resistant alpha-amylase was purchased from novacin biotechnology limited;

the maltulotetrase adopts Pesudomonas saccharophillia-sourced recombinant bacillus subtilis as a strain, 250g/L of soybean meal amino acid hydrolysate, 20g/L of peptone, 30g/L of glucose, 10g/L of glycerol and 10g/L of sodium glutamate are used as fermentation culture media to carry out fermentation for 48 hours, and the enzyme activity is 9 multiplied by 10⁵～2×10⁶U/L maltetraose;

pullulanase was purchased from bioengineering, Inc., Jenecaceae.

Example 1

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 13%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.01L per ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 4.2%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) adding pullulanase into the feed liquid in the step (4) to react for 1 hour, then adding maltotetraose to carry out saccharification reaction, wherein the addition amount of the maltotetraose and the pullulanase is 0.5L/ton of starch, and carrying out saccharification reaction for 12 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

DE value: is an abbreviation of Dextrose Equivalent English Dextrose Equivalent, and the reducing sugar in the saccharified liquid is calculated by taking the whole reducing sugar as the Dextrose and accounts for the mass percent of the dry matter.

As corn is the main product of starch, common corn starch is a mixture of amylose and amylopectin, the proportion of the amylose and the amylopectin is about 28 percent and 72 percent respectively, the content of the amylose is relatively high, and the maltotetraose is generated under the action of maltotetraose enzyme, so that the corn starch is adopted for tests in the embodiment, the subsequent embodiments and the comparative examples.

The optimal temperature range of the maltotetraose and the pullulanase is 55-65 ℃, the enzyme activity is weak greatly and the conversion rate of the maltotetraose is definitely reduced if the temperature exceeds the temperature range, so that the saccharification reaction is carried out when the temperature is reduced to 60 ℃ in the embodiment, the subsequent embodiments and the comparative examples.

Example 2

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.01L per ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with the DE value of 3.8%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) adding pullulanase into the feed liquid in the step (4) to react for 1 hour, then adding maltotetraose to carry out saccharification reaction, wherein the addition amount of the maltotetraose and the pullulanase is 0.5L/ton of starch, and carrying out saccharification reaction for 12 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

Example 3

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.045L/ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 5.3%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) adding pullulanase into the feed liquid in the step (4) to react for 1 hour, then adding maltotetraose to carry out saccharification reaction, wherein the addition amount of the maltotetraose and the pullulanase is 0.5L/ton of starch, and carrying out saccharification reaction for 12 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

Example 4

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.045L/ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 5.2%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) adding pullulanase into the feed liquid in the step (4) for reacting for 2 hours, then adding maltotetraose for carrying out saccharification reaction, wherein the addition amount of the maltotetraose and the pullulanase is 0.5L/ton of starch, and carrying out saccharification reaction for 12 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

Example 5

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.045L/ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 5.2%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) adding pullulanase into the feed liquid in the step (4) for reacting for 2 hours, then adding maltotetraose for carrying out saccharification reaction, wherein the adding amount of the maltotetraose and the pullulanase is 1.5L/ton of starch, and carrying out saccharification reaction for 12 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

Example 6

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.045L/ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 5.3%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) adding pullulanase into the feed liquid in the step (4) for reacting for 2 hours, then adding maltotetraose for carrying out saccharification reaction, wherein the adding amount of the maltotetraose and the pullulanase is 1.5L/ton of starch, and carrying out saccharification reaction for 5 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

Example 7

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.045L/ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 5.3%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) adding pullulanase into the feed liquid in the step (4) for reacting for 2 hours, then adding maltotetraose for carrying out saccharification reaction, wherein the adding amount of the maltotetraose and the pullulanase is 1.5L/ton of starch, and carrying out saccharification reaction for 18 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

Comparative example 1

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.1L per ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 6.8%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) adding pullulanase into the feed liquid in the step (4) to react for 1 hour, then adding maltotetraose to carry out saccharification reaction, wherein the addition amount of the maltotetraose and the pullulanase is 0.5L/ton of starch, and carrying out saccharification reaction for 12 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

Comparative example 2

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.045L/ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 5.2%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) simultaneously adding pullulanase and maltotetrase into the feed liquid in the step (4) to carry out saccharification reaction, wherein the addition amount of the maltotetrase and the pullulanase is 0.5L/ton of starch, and obtaining reaction liquid after 12 hours of saccharification reaction;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

Comparative example 3

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.045L/ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 5.3%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) adding pullulanase into the feed liquid in the step (4) for reacting for 3 hours, then adding maltotetraose for carrying out saccharification reaction, wherein the addition amount of the maltotetraose and the pullulanase is 0.5L/ton of starch, and carrying out saccharification reaction for 12 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

Comparative example 4

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.045L/ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 5.2%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) adding pullulanase into the feed liquid in the step (4) for reacting for 2 hours, then adding maltotetraose for carrying out saccharification reaction, wherein the addition amount of the maltotetraose and the pullulanase is 2L/ton of starch, and carrying out saccharification reaction for 12 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

Comparative example 5

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.045L/ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 5.3%;

(4) naturally cooling the liquefied liquid prepared in the step (3) to 60 ℃;

(5) adding pullulanase into the feed liquid in the step (4) for reacting for 2 hours, then adding maltotetraose for carrying out saccharification reaction, wherein the adding amount of the maltotetraose and the pullulanase is 1.5L/ton of starch, and carrying out saccharification reaction for 12 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

Comparative example 6

(1) Adding water into corn starch to prepare starch slurry, wherein the mass concentration of dry substances in the starch slurry is 21.5%, and the pH value of the starch slurry is adjusted to 6.0;

(2) adding high-temperature-resistant alpha-amylase into the starch slurry in the step (1), wherein the addition amount is 0.045L/ton of starch;

(3) performing primary spray liquefaction on the feed liquid in the step (2) at 110 ℃ for 15min, preserving the heat of a laminar flow tank for 80min, and performing secondary spray liquefaction at 130 ℃ for 10min to obtain a liquefied liquid with a DE value of 5.3%;

(4) rapidly cooling the liquefied liquid prepared in the step (3) to 60 ℃ through a flash evaporation heat exchanger;

(5) adding pullulanase into the feed liquid in the step (4) for reacting for 2 hours, then adding maltotetraose for carrying out saccharification reaction, wherein the adding amount of the maltotetraose and the pullulanase is 1.5L/ton of starch, and carrying out saccharification reaction for 20 hours to obtain reaction liquid;

(6) and (3) decoloring the reaction solution by using granular carbon, performing ion exchange and concentrating to obtain the oligomeric maltose syrup.

After the saccharification reaction was completed, the content of each component in the reaction solution of each example and each comparative example was measured, and the measurement results are shown in table 1.

TABLE 1

As can be seen from Table 1, in examples 1 and 2, when the enzyme addition amount is consistent, the DE value of the liquefied solution is significantly reduced with the increase of the mass concentration of the dry matter in the starch slurry, and when the DE value is lower, the chance of producing oligosaccharides with odd polymerization degrees is less, which is beneficial to improving the content of maltotetraose in the final product.

The mass concentration of dry substances in the starch slurry is too low (< 13%), which is also beneficial to the generation of maltotetraose, but the subsequent concentration load is aggravated when the concentration is too low, so that the cost is increased; maltotetraose can also be produced at too high a mass concentration (> 21.5%) of dry matter in the starch slurry, but the feed liquid is thick during liquefaction and is not conducive to pipeline flow.

It can be seen from examples 2 and 3 that the higher the DE value of the liquefied solution, the higher the DE value, the more difficult the binding of the maltotetralase to the target substrate, and the more unfavorable the hydrolysis of the substrate, the lower the final content of maltotetraose, probably because the shorter the dextrin molecular chain in the liquefied solution system, and especially the higher the content of small molecules such as glucose and maltose, the higher the DE value increases. Observing comparative example 1, when the addition amount of the alpha-high temperature amylase is further increased, the DE value is obviously increased, the content of the maltotetraose is further reduced, and the comparative example 1 can verify that the higher the DE value is, the disadvantage of improving the content of the maltotetraose is avoided.

It can be seen from examples 3 and 4 that the content of maltotetraose in the final product increases with the time interval between the addition of pullulanase and the addition of maltotetraose. This is attributed to the fact that when maltotetraose acts on amylose, α -1,4 glycosidic linkages are cleaved at 4 glucose molecules in sequence to yield maltotetraose, which can also be produced if the substrate consists of an odd number of glucose units; maltose molecules can also be produced if the substrate is composed of an even number of glucose units and is not an integer multiple of 4. However, the action of maltotetraose to hydrolyze amylopectin is incomplete, and when the branch point α -1,6 bond is encountered, the action is hindered, and no further hydrolysis is possible, leaving a certain amount of limiting dextrin. Since most starches contain 75-85% amylopectin, in order to increase the yield of maltotetraose, an exonuclease, pullulanase, which cleaves the alpha-1, 6 glucosidic bonds in amylopectin, must be used. Pullulanase firstly hydrolyzes amylopectin, cuts alpha-1, 6 bonds to convert most of the amylopectin into amylose, and then maltotetraose is added for synergistic action.

In contrast to comparative example 2 and comparative example 3, in comparative example 2, pullulanase and maltotetraose are added simultaneously to perform saccharification reaction, and the content of maltotetraose in the final product is reduced, probably because no time is provided for converting most of amylopectin into amylose by the pullulanase, the conversion rate of the maltotetraose is not influenced, and the saccharification time is also prolonged appropriately, so that the content of maltotetraose in the final product is influenced;

comparative example 3 further increased the time interval between the addition of the two enzymes and the same decreased the amount of maltotetraose in the final product, probably because the pullulanase was acting for too long first and the chain length was too short when the maltotetraose was acting again, which in turn did not favor the maltotetraose enzyme to perform a 4 fold cut, thus affecting the amount of maltotetraose in the final product.

It can be seen from examples 4 and 5 that the content of maltotetraose in the final product increases as the addition amount of pullulanase and maltotetraose increases. In contrast to comparative example 4, when the amounts of pullulanase and maltotetraose added were too large, the content of maltotetraose in the final product decreased, which may be caused by the excessively large amount of pullulanase, because the chain length of linear dextrin may be too short due to the excessively large amount of pullulanase added, and when maltotetraose was removed again, the cleavage by a factor of 4 by maltotetraose was adversely affected, thereby affecting the content of maltotetraose in the final product.

As can be seen by comparing the example 5 with the comparative example 5, the DE value of the liquefied liquid cannot be obviously changed by adopting the flash evaporation heat exchanger to rapidly cool, but the content of the maltotetraose in the final product of the comparative example 5 is reduced by 9.29 percent compared with the example 5, the situation that the maltotetraose is difficult to filter during subsequent filtration occurs, the iodine is blue in test, and the transparent color can be formed only by filtering for a plurality of times, which indicates that the feed liquid of the comparative example 5 has a regeneration phenomenon, and because the amylodextrin has an aging point at 80-90 ℃, if the temperature is not reduced in time, the regeneration is easy, the conversion rate of the maltotetraose is influenced; in order to solve the problem that the starch dextrin is easy to regenerate, the flash evaporation heat exchanger is adopted to rapidly cool, an aging point between 80 and 90 ℃ is rapidly skipped, the starch aging and regeneration can be really prevented, the subsequent filtration is not affected, the dextrin aging is prevented, and the conversion rate of the maltotetraose is improved.

As can be seen from examples 5, 6 and 7, when the saccharification reaction time in example 6 is 5 hours, the content of maltotetraose in the final product is 65.21%, which is just over 65%, and the saccharification reaction time is less than 5 hours, the content of maltotetraose in the final product may not reach 65%; the content of maltotetraose in the final product could be increased with the time of saccharification, in example 5, the content of maltotetraose in the final product reached 67.85% at 12h of saccharification, but in example 7, although the content of maltotetraose in the final product still exceeded 65% at 18h of saccharification, the content of maltotetraose was decreased compared to example 5, and in comparative example 6, the content of maltotetraose in the final product reached 65% at 20h of saccharification, probably because maltotetraose gradually decomposed with the time of saccharification, and the final content gradually decreased.

It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.