CN107163154B

CN107163154B - Modified starch for dried fruit film formation and preparation method and application thereof

Info

Publication number: CN107163154B
Application number: CN201710514472.2A
Authority: CN
Inventors: 吴宗帅; 张淑芬; 吴磊; 朱津津; 张永; 胡荣柳; 付华杰
Original assignee: Henan Hengrui Starch Technology Co Ltd
Current assignee: Henan Hengrui Starch Technology Co Ltd
Priority date: 2017-06-29
Filing date: 2017-06-29
Publication date: 2019-12-10
Anticipated expiration: 2037-06-29
Also published as: CN107163154A

Abstract

The invention relates to the technical field of modified starch and application thereof, in particular to modified starch for dried fruit film formation and a preparation method and application thereof. In the preparation process of the modified starch, the pH of the original starch slurry is adjusted to be alkaline, then the temperature is raised, 2-4 parts of oxidant is added, 3-5 parts of vinyl acetate is added after oxidation reaction to serve as an esterification reagent, and the esterification time is controlled to be 2-4 hours. The dry fruit film-forming slurry prepared by the modified starch can form a layer of uniform, compact and tightly combined starch film on the surface of the dry fruit, can effectively prevent the dry fruit from mildewing, simultaneously achieves the effects of increment, weight increment and crisping, and improves the economic value of the dry fruit.

Description

modified starch for dried fruit film formation and preparation method and application thereof

Technical Field

The invention relates to the technical field of modified starch and application thereof, in particular to modified starch for dried fruit film formation and a preparation method and application thereof.

Background

The dried fruit food is mainly prepared from nut seeds, nuts and the like serving as main raw materials, with or without auxiliary materials, and is fried or baked, and comprises fried food, dried fruit food and nut food. The dried fruit food is rich in nutrition, contains high content of protein, oil, mineral substances and vitamins, and has excellent effects of promoting growth and development of human body, improving body condition and preventing diseases. However, dry fruit foods also have some potential hazard problems that are easily overlooked by people: 1. many dried fruit products are susceptible to mold infestation, which can be extremely harmful to human health, especially in southern areas of high temperature and high humidity. 2. Many dried fruits, especially nuts, contain a large amount of unsaturated fatty acids, and on the one hand, such ingredients have special nutritional values, but are also prone to oxidative rancidity. In view of these problems, the temperature and humidity of storage are often reduced and suitable packaging materials are used, but these do not fundamentally solve the quality problems of dried fruit products.

In order to enhance the tolerance of dry fruit products to high-temperature and high-humidity environments, film substances, such as sugar, chocolate and the like, are formed on the surfaces of the dry fruits, and the film substances are expected to form a protection effect on the internal dry fruits, but the film formed by sugar liquid or the film formed by chocolate cannot tolerate high temperature, can melt under the high-temperature condition, cannot generate the protection effect on the dry fruits, and the too strong flavor of the sugar liquid or the chocolate affects the flavor of the dry fruits and cannot meet the requirement of the public on the flavor of the dry fruits. In view of the above, in recent years, in consideration of certain film forming properties of starch, starch has been used to replace conventional sugar or chocolate to prepare dried fruit film-forming slurry, and a starch film is formed on the surface of dried fruit by the film forming property of starch to protect the dried fruit. However, the starch product applied to film forming of the dried fruits at present generally has the defects of high viscosity, poor film forming property, low transparency and low bonding force with the dried fruits and easy falling off, so that the appearance and the shape of the dried fruits after film forming are not beautiful enough, the taste of the dried fruits is influenced, and the improvement effect on the high-temperature resistant and high-humidity environment of the dried fruits cannot meet the actual requirement.

Based on the current situation, the modified starch special for dry fruit film coating is researched and developed, so that the high-temperature resistance and humidity resistance of the product are effectively improved, the product is effectively prevented from mildewing, the effects of brightening, increasing weight and increasing crispness are achieved, and the modified starch has important significance for the development of industrialization and marketization of dry fruit products.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide the modified starch for dry fruit film coating, which has the advantages of low and stable viscosity, transparent paste, weak retrogradation, strong film forming property and good film coating property.

the second purpose of the invention is to provide a preparation method of modified starch for dried fruit film formation.

meanwhile, the invention also aims to provide the application of the modified starch for dry film coating, which is used for coating the dried fruits, and a plurality of dense and bright starch films are formed on the surfaces of the dried fruits, so that the brightness and the brittleness of the products are improved, the high temperature resistance and the moisture resistance of the products are improved, and the products are prevented from mildewing.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

A preparation method of modified starch for dried fruit film formation comprises the following operation steps:

1) adding 100 parts of raw starch into 120-200 parts of water, and uniformly stirring and dispersing to obtain raw starch slurry;

2) Adding an alkaline pH regulator into the raw starch slurry prepared in the step 1) to regulate the pH value to be 7.5-8.0, and heating to 30-35 ℃;

3) Adding 2-4 parts of oxidant into the raw starch slurry treated in the step 2), heating to 35-40 ℃, maintaining the pH value at 8.0-9.5, reacting for 1-5 hours, adding a reducing agent, and stopping the oxidation reaction to obtain oxidized starch slurry;

4) Adjusting the pH value of the oxidized starch slurry prepared in the step 3) to 9.0-10.5, adding 3-5 parts of vinyl acetate at the temperature of 35-40 ℃, reacting for 2-4 hours, and adding an acidic pH regulator to adjust the pH value to 5.0-7.0 to obtain oxidized esterified modified starch slurry;

5) Washing, filtering, drying and crushing the oxidized esterified modified starch slurry prepared in the step 4) in sequence to obtain oxidized esterified modified starch, namely the modified starch for dried fruit film formation.

optionally, the oxidant is sodium hypochlorite or hydrogen peroxide with the mass concentration of 30%.

optionally, the alkaline pH regulator is a sodium hydroxide solution with the mass concentration of 2-3%.

Optionally, the acidic pH regulator is a hydrochloric acid solution with a mass concentration of 10-20%.

Optionally, the reducing agent is added in the step 3) in an amount of 1-2 parts by weight.

Optionally, the reducing agent is one of sodium sulfite, sodium bisulfite and sodium thiosulfate.

Optionally, the stirring time in step 1) is 30 minutes.

Optionally, the native starch is tapioca starch and/or potato starch.

optionally, the modified starch for dried fruit film forming is prepared by the method.

The modified starch for dry fruit film formation can be used for preparing slurry for dry fruit film formation.

Optionally, the slurry for film formation of the dried fruits is prepared from the following raw materials in parts by weight: 10 parts of modified starch, 1 part of edible oil, 5 parts of salt, 10 parts of white sugar, 3 parts of five spice powder, 1 part of clove, 0.1 part of essence and 90 parts of water according to claim 6.

optionally, the slurry for dried fruit film formation is prepared by a method comprising the following operation steps:

A: adding modified starch into water to prepare starch slurry with the mass concentration of 10%, and heating to 85-90 ℃ to gelatinize the modified starch to prepare a solution A;

B: adding edible oil, salt, white sugar, five spice powder, clove and essence into the solution A, and uniformly mixing to obtain the serous fluid for film forming of the dried fruits.

the specific method for film formation of the dried fruits comprises the following steps: and adding 100 parts of dried fruits needing film forming into the slurry for film forming of the dried fruits, stirring for 20-30 minutes, taking out the dried fruits, draining water, and drying to obtain the finished product.

The modified starch for dried fruit film formation is oxidized esterified modified starch prepared by oxidizing and then esterifying original starch, wherein the pH of original starch slurry is adjusted to be alkaline, 2-4 parts of oxidant is added after the temperature is raised, 3-5 parts of vinyl acetate is added after oxidation reaction as an esterification reagent, and the esterification time is controlled to be 2-4 hours. The oxidation and esterification degree of the original starch is further controlled by controlling the temperature, the reaction time (especially the esterification reaction time), the addition amount of the oxidant and the esterifying agent, so that the prepared oxidation esterification modified starch has low and stable viscosity, transparent paste, weak retrogradation, strong film forming property and good film forming property, and is suitable for film forming of dry fruits.

specifically, the modified starch for film formation of the dried fruits has the following advantages:

(1) Common starch is used as a raw material, the source is wide, the price is low, and the film forming agent meets the demand and brings profits for the dry fruit industry;

(2) The advantages of the oxidized and esterified modified starch are comprehensively considered, the gelatinization temperature of the product is low, the fluidity is good, the paste is transparent and bright, a layer of compact protective film can be formed on the surface of the product, the moisture absorption and moisture regain of the dried fruit product can be effectively prevented, the caking or mildew growing is avoided, and the quality guarantee period of the product is prolonged;

(3) The invention controls the temperature, the raw material dosage, the temperature, the reaction time and other conditions in the oxidation and esterification reactions, so that the prepared oxidized esterified modified starch has strong permeability, good film-coating property, good intersolubility and affinity with salts and spices, and can effectively load the spices into dry fruits;

(4) the modified starch prepared by the invention is used as a film forming agent specially used for dried fruits, so that the product achieves the effects of weight increment, crispness increment and brightness increment, and optimistic economic benefits are brought to enterprises;

(5) the modified starch prepared by the invention is applied to the dried fruit film coating agent, does not change the original production process of dried fruit products, and is convenient to operate.

(6) the modified starch is produced at normal pressure and low temperature, the production equipment is simple, the process conditions are easy to control, large-scale industrial production is easy to realize, the operation is easy, and the practicability is high.

Detailed Description

The technical solution of the present invention will be described in detail by specific examples.

Example 1

The modified starch for dried fruit film formation is prepared by the following method, and the specific operation steps are as follows:

1) taking 100 parts of cassava starch, adding 150 parts of water, and stirring and dispersing for 30 minutes to obtain raw starch slurry;

2) Adding a sodium hydroxide solution with the mass concentration of 2.5% into the raw starch slurry prepared in the step 1), adjusting the pH value of the raw starch slurry to 7.8, and heating to 32 ℃;

3) Adding 3 parts of sodium hypochlorite into the raw starch slurry treated in the step 2), heating to 38 ℃, maintaining the pH value at 8.0-9.5, reacting for 3 hours, adding 1.5 parts of sodium sulfite, and stopping the oxidation reaction to obtain oxidized starch slurry;

4) adjusting the pH value of the oxidized starch slurry prepared in the step 3) to 10, adding 4 parts of vinyl acetate at the temperature of 38 ℃, reacting for 3 hours, and adding a hydrochloric acid solution with the mass concentration of 15% to adjust the pH value to 6.0 to obtain oxidized esterified modified starch slurry;

5) Cooling the oxidized esterified modified starch slurry prepared in the step 4), washing the oxidized esterified modified starch slurry by using tap water in sequence, and performing suction filtration, drying and crushing treatment to obtain the oxidized esterified modified starch, namely the modified starch for dried fruit coating.

Example 2

1) Adding 100 parts of potato starch into 120 parts of water, and stirring and dispersing for 30 minutes to obtain raw starch slurry;

2) adding a sodium hydroxide solution with the mass concentration of 2.0% into the raw starch slurry prepared in the step 1), adjusting the pH value of the raw starch slurry to 7.5, and heating to 30 ℃;

3) Slowly adding 2 parts of sodium hypochlorite into the raw starch slurry treated in the step 2) under the condition of continuous stirring, heating to 35 ℃, maintaining the pH value to be 8.0-9.5, reacting for 5 hours, adding 1 part of sodium bisulfite, and stopping the oxidation reaction to obtain oxidized starch slurry;

4) adjusting the pH value of the oxidized starch slurry prepared in the step 3) to 9.0, adjusting the temperature to 35 ℃, adding 3 parts of vinyl acetate, reacting for 4 hours, and adding a hydrochloric acid solution with the mass concentration of 10% to adjust the pH value to 7.0 to obtain oxidized esterified modified starch slurry;

Example 3

1) Adding 100 parts of cassava starch into 200 parts of water, and stirring and dispersing for 30 minutes to obtain raw starch slurry;

2) adding a sodium hydroxide solution with the mass concentration of 3.0% into the raw starch slurry prepared in the step 1), adjusting the pH value of the raw starch slurry to 8.0, and heating to 35 ℃;

3) Adding 4 parts of hydrogen peroxide with the mass concentration of 30% into the raw starch slurry treated in the step 2), heating to 40 ℃, maintaining the pH value to be 8.0-9.5, reacting for 1 hour, adding 2 parts of sodium thiosulfate, and stopping the oxidation reaction to obtain oxidized starch slurry;

4) adjusting the pH value of the oxidized starch slurry prepared in the step 3) to 10.5, adding 5 parts of vinyl acetate at the temperature of 40 ℃, reacting for 2 hours, and adding a hydrochloric acid solution with the mass concentration of 20% to adjust the pH value to 5.0 to obtain oxidized esterified modified starch slurry;

Example 4

the modified starch prepared in the above examples 1 to 3 can be used for preparing slurry for dry fruit film coating, and the slurry for dry fruit film coating is prepared from the following raw materials in parts by weight: 10 parts of modified starch for film forming of dried fruits, 1 part of edible oil, 5 parts of salt, 10 parts of white sugar, 3 parts of five spice powder, 1 part of clove, 0.1 part of essence and 90 parts of water.

The specific method for performing the film formation on the dried fruits by adopting the slurry for the film formation on the dried fruits comprises the following steps:

A: adding modified starch for film formation of dried fruits into water to prepare starch slurry with the mass concentration of 10%, and heating to 85-90 ℃ to gelatinize the modified starch to prepare a solution A;

B: adding edible oil, salt, white sugar, five spice powder, clove and essence into the solution A, and uniformly mixing to obtain slurry for film forming of the dried fruits;

c: and C, adding 100 parts of pre-dried fruits into the slurry for film formation of the dried fruits prepared in the step B, stirring for 20-30 minutes, taking out the dried fruits, draining water, and drying to obtain the finished product.

comparative example 1

The modified starch of this comparative example is different from example 1 in that 10 parts of sodium hypochlorite was directly added to the slurry of the native starch in step 2) without heating the slurry to 32 ℃ after adjusting the pH, and 40 parts of vinyl acetate was added in step 4), and the same as example 1 was repeated.

comparative example 2

The modified starch of this comparative example is different from example 1 in that the temperature rise operation is not performed in step 2) and step 3), the oxidation reaction and the esterification reaction are both performed at room temperature, 5 parts of sodium hypochlorite is added in step 3), the esterification reaction time in step 4) is 1 hour, and the other steps are the same as example 1.

comparative example 3

The modified starch of this comparative example was the same as that of example 1 except that rice starch was used as a raw material.

Comparative example 4

This comparative example modified starch differs from example 1 in that acetic anhydride was added as an esterification reagent in step 4), otherwise the same as in example 1.

Test examples

1) the light transmittance of the modified starches prepared in example 1 and comparative examples 1 to 4 was measured, and the detection method was: modified starch is weighed, 100mL of double distilled water is added to prepare 1% starch solution, then the starch solution is heated and gelatinized for 30min in a boiling water bath, and the concentration of the starch solution is kept unchanged in the whole process and is continuously stirred. Cooling the gelatinized starch solution to room temperature, then placing the starch solution at 4 ℃ for 0, 1d, 3d, 5d and 7d, and respectively measuring the transmittance of the starch solution after being placed for a certain time at 620nm by using an ultraviolet-visible spectrophotometer, wherein the results are shown in the following table 1:

TABLE 1

from the data in table 1 above, it can be seen that: in the storage process, the light transmittance of the oxidized esterified starch prepared according to the embodiment 1 is far better than that of the oxidized esterified starch prepared according to the comparative examples 1-4, and the oxidized esterified starch is more suitable for film formation of dried fruits.

2) The freeze-thaw stability of the modified starches prepared in example 1 and comparative examples 1 to 4 was determined, and the detection method was: preparing modified starch into 3% starch solution with double distilled water, placing in boiling water for 30min, continuously stirring while boiling water bath to keep starch emulsion, cooling to room temperature, weighing, placing in refrigerator freezer (-20 deg.C) for 24h, taking out, naturally thawing at room temperature, centrifuging at 4000r/min in high speed centrifuge for 20min, discarding supernatant, and weighing, wherein the water-separating rate is calculated as follows:

The high and low water separating rate is the embodiment of the freeze-thaw stability of the starch, and the lower the water separating rate is, the better the freeze-thaw stability of the starch is. The main internal factor affecting starch retrogradation is the molecular composition of starch, since amylose structure determines its low steric hindrance in solution and its tendency to rearrange and associate to retrogradation, which pushes out the water bound by the starch molecules, resulting in poor water holding capacity and resistance to freezing, and therefore, the higher the amylose content, the poorer the freeze-thaw stability, as measured in table 2 below:

TABLE 2

	example 1	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4
						Water analysis rate (%)	40	53	70	68	60

As can be seen from the data shown in table 2 above: the water precipitation rate of the oxidized esterified starch prepared in the embodiment 1 is far lower than that of the oxidized esterified starch prepared in the comparative examples 1-4, and the oxidized esterified starch prepared by the method has good water retention property and good stability.

3) The ageing resistance of the modified starch prepared in example 1 and comparative examples 1-4 is determined, and the detection method comprises the following steps: weighing 1.0g of modified starch to prepare a starch suspension with the mass fraction of 1.0%, placing the starch suspension in boiling water for gelatinization for 20min, cooling to room temperature, placing the starch paste into a 100mL measuring cylinder, standing for 0, 6, 12, 24, 36 and 48h at 4 ℃, recording the volume of a supernatant, and calculating the volume ratio of the supernatant to the total volume of the starch suspension. Because retrogradation of starch is related to aging of starch, retrogradation is generated due to aging of starch in the standing process after starch gelatinization, the test mainly reflects the aging characteristic of starch under the condition of sufficient moisture, the change of the volume of supernatant fluid reflects the retrogradation trend of starch paste, the larger the volume of supernatant fluid is, the higher the retrogradation degree of starch is, the starch aging degree is represented by the volume ratio of the supernatant fluid, and the results are shown in the following table 3:

TABLE 3

As can be seen from the data shown in table 3 above: with the increase of the standing time, the volume of the supernatant of the oxidized esterified starch prepared in the embodiment 1 is far lower than that of the oxidized esterified starch prepared in the comparative examples 1-4, and the oxidized esterified starch prepared in the invention has a good retrogradation inhibition effect.

4) The modified starches prepared in example 1 and comparative examples 1 to 4 were subjected to dry fruit coating according to the dry fruit coating method shown in example 4, and the dry fruit coating effects of different modified starches were compared, and the statistical results are shown in the following table 4:

TABLE 4

The test results in the table 4 show that the dry fruit filming effect of the starch prepared in the embodiment 1 of the invention is obviously better than that of the starch prepared in the comparative examples 1-4.

Tests prove that the performances of the modified starch prepared in the example 2 and the example 3 of the invention are basically equivalent to those of the modified starch prepared in the example 1.

as can be seen from the test results of 1), 2), 3) and 4), the invention adopts cassava starch or potato starch as a raw material, controls the addition amount of an oxidant and an esterifying agent, the heating time and the esterification reaction time in the oxidation and esterification processes, and further controls the oxidation and esterification degree of the starch, so that the obtained oxidized and esterified modified starch has good permeability and film forming property, is transparent and bright in paste liquid, is suitable for being used as a dried fruit film, can form a layer of compact protective film on the surface of a product, effectively prevents the dried fruit product from absorbing moisture and regaining moisture, avoids caking or mildewing, and prolongs the shelf life of the product.

Claims

1. The preparation method of the modified starch for dried fruit film formation is characterized by comprising the following operation steps: 1) adding 100 parts of raw starch into 120-200 parts of water, and uniformly stirring and dispersing to obtain raw starch slurry, wherein the raw starch is cassava starch and/or potato starch;

2. The method for preparing the modified starch for dried fruit coating according to claim 1, wherein the alkaline pH regulator is a sodium hydroxide solution with a mass concentration of 2-3%.

3. The method for preparing the modified starch for dried fruit coating according to claim 1, wherein the acidic pH regulator is a hydrochloric acid solution with a mass concentration of 10-20%.

4. The method for preparing the modified starch for dried fruit coating according to claim 1, wherein the reducing agent is added in the step 3) in an amount of 1-2 parts by weight.

5. A modified starch for dried fruit coating, which is prepared by the method of any one of claims 1 to 4.

6. Use of a modified starch according to claim 5 for the preparation of a slurry for dry fruit filming.

7. The use of claim 6, wherein the slurry for dry fruit filming is prepared from the following raw materials in parts by weight: 10 parts of modified starch, 1 part of edible oil, 5 parts of salt, 10 parts of white sugar, 3 parts of five spice powder, 1 part of clove, 0.1 part of essence and 90 parts of water.

8. the use of claim 7, wherein the slurry for dry fruit filming is prepared by a method comprising the steps of:

9. The use of claim 7, wherein the specific method of dried fruit filming is as follows: and adding 100 parts of dried fruits needing film forming into the slurry for film forming of the dried fruits, stirring for 20-30 minutes, taking out the dried fruits, draining water, and drying to obtain the finished product.