An oil-processed starch and a method for preparing the same

Abstract

The application discloses oil processing starch and a preparation method thereof, and belongs to the technical field of modified starches. The method comprises the following steps: balancing moisture, phospholipid-fatty acid co-spraying, oil co-melting adding, gradient dehydration and ripening. The method of the phospholipid-fatty acid co-spraying is as follows: lecithin and fatty acid are dissolved in an ethanol aqueous solution at 50-55 DEG C, and are atomized and sprayed on the surface of starch; the spraying time is 25-35 min; the system temperature is controlled to be 43-47 DEG C under stirring during the spraying process; and the activated starch is obtained by continuing stirring for 4-6 min after spraying. The oil processing starch prepared by the method has the advantages that oil is uniformly distributed in the starch, no obvious agglomeration is generated, and the combination is stable, so that the oil exudation can be reduced; meanwhile, the slurry prepared by using the oil processing starch can meet the adhesion requirement of fried coating, and the oil absorption rate of frying can be reduced.

Description

Technical Field

[0001] This invention belongs to the technical field of modified starch, specifically relating to an oil-processed starch and its preparation method. Background Technology

[0002] Processed starch is obtained by adding a small amount of edible oil to starch and then subjecting it to a cooking process. Because the oil adheres to or binds to the surface of the starch granules, it imparts a good crispy texture and binding properties to the coating when used as a batter for fried foods. Therefore, it is widely used as a raw material for batter and dusting powder in fried foods. In addition, to improve yield and texture, processed starch is also used in processed meat products such as sausages and hamburger patties, as well as savory seafood products such as fish cakes and chikuwa.

[0003] Various oil-based starch processing techniques and their manufacturing methods have been disclosed in the prior art. A detailed analysis based on relevant patent literature is provided below:

[0004] Patent document 1 (CN110352013A) discloses an oil-processed starch obtained by aging sunflower seed oil with a linoleic acid content of more than 40%. This product can give fried foods a sticky and crispy texture, but it does not pay attention to the balance between dispersibility and slurry viscosity. In practical applications, the batter is prone to insufficient adhesion or uneven dispersion.

[0005] Patent document 2 (CN110913705A) discloses a product obtained by combining corn starch, tapioca starch, edible oil and protein raw materials for oil processing. The performance of the dough is improved by the combination of raw materials, but it does not involve the optimization of the binding mechanism between oil and starch. The oil is easy to bleed out, resulting in poor product storage stability.

[0006] Patent document 3 (CN116390654A) proposes a dual-oil system for processing starch, which includes a first oil with an iodine value of 120 or higher and a second oil with an iodine value of 119 or lower, in order to improve the dispersibility of the product. However, it does not solve the problem of decreased slurry viscosity and weakened adhesion function after the dispersibility is improved, and cannot take into account both dispersibility and adhesion.

[0007] Patent document 4 (CN103561587A) specifies that the solubility of starch in oil processing is 9.5~45wt% and the emulsification capacity is 50%~100%, focusing on the macroscopic performance control of the product, but not on the microstructure and application performance, and cannot fundamentally solve the problems of weak oil binding and high oil absorption rate.

[0008] Patent document 5 (CN115379767A) focuses on the sugar composition of the water-soluble portion in the aqueous suspension, limiting the sugar content of a degree of polymerization of 13 to 3~20wt%, but fails to establish a direct correlation between this microstructure feature and the product's dispersibility, adhesion, oil absorption rate and other application performance, and cannot achieve precise optimization of product performance through microstructure regulation.

[0009] Patent document 6 (CN120322158A) discloses a processed starch and an edible meat modifier containing the processed starch. It is mainly used for modifying edible meat, but it is not optimized for the core requirements of the coating of fried food, such as dispersibility, adhesion and oil absorption rate, and cannot meet the usage requirements of coating materials.

[0010] Patent document 7 (CN110248557A) uses an oil composition with an iodine value of 125~170 and containing polyphenols for aging treatment, which mainly improves the stability of the oil itself, but does not involve the optimization of the combination mode of starch and oil, and still has the technical pain point of difficulty in achieving both dispersibility and viscosity.

[0011] Patent document 8 (CN104754958A) proposes a method to react starch with an emulsifier mixed with oil by adjusting the moisture content to 25-45 wt%, then adjusting the moisture content and aging the mixture. Although this method improves the oil dispersibility through the emulsifier, the addition of the emulsifier will cause the viscosity of the slurry to decrease excessively, thereby reducing the adhesive function of the starch. If the degree of heating and aging is increased to improve the viscosity, the adhesive function will be further damaged due to heat damage, forming a typical technical contradiction.

[0012] Based on existing technologies, the following technical problems still exist and urgently need to be solved:

[0013] First, it is difficult to balance dispersibility and slurry viscosity. As described in Patent Document 8 (CN104754958A), although the dispersibility of oil in starch can be improved by adding emulsifiers, the slurry viscosity is often reduced excessively when preparing the batter, resulting in a decrease in the adhesion function of oil-processed starch; although increasing the degree of heating and cooking can increase the slurry viscosity, thermal damage will further reduce the adhesion function.

[0014] Secondly, the oil absorption rate of existing products still needs to be reduced. Processed starch itself contains a certain amount of oil, and when used as a coating for fried foods, it further absorbs a large amount of oil during the frying process, resulting in an excessively high total fat content in the final product. This does not meet consumers' demand for low-fat, healthy foods, and existing technologies have not solved this problem at the level of the starch-oil binding mechanism.

[0015] Therefore, there is still a need in this field to develop an oil-processed starch that has both excellent dispersibility and moderate slurry viscosity to ensure adhesion, as well as low oil absorption characteristics, to solve some of the pain points of existing technologies. Summary of the Invention

[0016] To address the shortcomings of existing technologies, this invention provides a processed starch and its preparation method. The processed starch prepared by this invention has uniformly distributed oil in the starch without obvious agglomeration and stable binding, which can reduce oil seepage. At the same time, the slurry prepared with it can meet the adhesion requirements of fried dough coating and reduce the oil absorption rate during frying.

[0017] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0018] A method for preparing oil-processed starch includes the following steps: balancing moisture, co-spraying phospholipids and fatty acids, co-melting and adding oils, gradient dehydration, and maturation;

[0019] The method for balancing moisture is to place starch in an environment with a relative humidity of 75%-80% to equilibrate it, thereby obtaining moisture-balanced starch.

[0020] The starch is corn starch;

[0021] In the moisture balancing step, the temperature is 23-27 ℃ and the balancing time is 0.7-0.9 h.

[0022] The method of co-spraying phospholipids and fatty acids is as follows: lecithin and fatty acids are dissolved in an ethanol-water solution at 50-55 ℃, and atomized and sprayed onto the starch surface for 25-35 min. During the spraying process, the system temperature is controlled at 43-47 ℃ under stirring conditions. After spraying, stirring is continued for 4-6 min to obtain activated starch.

[0023] The stirring speed is 100-150 r / min;

[0024] The concentration of the ethanol aqueous solution is 60%-70%;

[0025] The fatty acid is a mixture of stearic acid and oleic acid in a mass ratio of 8:1.8-2.2;

[0026] The mass ratio of the lecithin, fatty acids, aqueous ethanol solution to starch dry basis is 0.8-1.2:1.5-2.5:12-16:100;

[0027] The starch dry basis refers to the absolute dry weight of starch.

[0028] The method of adding oil and fat co-fusion is as follows: medium-chain triglycerides are mixed with high-oleic sunflower seed oil and added to activated starch under stirring by atomization. The addition time is 13-16 min, the temperature is maintained at 50-55 ℃, and stirring is continued for 4-6 min after addition to obtain oil-fat composite starch.

[0029] The medium-chain triglycerides and high-oleic sunflower seed oil are mixed at a temperature of 35-40 ℃;

[0030] The stirring speed is 80-100 r / min;

[0031] In the fatty acid composition of the medium-chain triglycerides, the proportion of saturated fatty acids with 8 and 10 carbon atoms is ≥90wt%.

[0032] The mass ratio of the medium-chain triglycerides, high-oleic sunflower seed oil, and starch (dry basis) is 0.4-0.6:1.5-1.8:100.

[0033] The high-oleic sunflower seed oil has an oleic acid content of >75%.

[0034] The gradient dehydration method involves a two-stage dehydration process. In the first stage, the temperature is controlled at 38-42 ℃ and the air velocity at 1.1-1.3 m / s for 28-32 min, during which the material is turned over to remove surface free moisture. In the second stage, the temperature is controlled at 43-47 ℃ and the air velocity at 0.6-0.8 m / s for 55-65 min, during which the material is turned over to obtain dehydrated starch.

[0035] The frequency of turning the material in the first stage is 8-12 times / min;

[0036] The frequency of turning the material in the second stage is 3-5 times / min;

[0037] The dehydrated starch has a moisture content of 8-12%.

[0038] The maturation method involves placing the dehydrated starch in a sealed environment, controlling the temperature at 42-46 ℃, and allowing it to mature for 18-22 hours to finally obtain oil-processed starch.

[0039] The oil-processed starch obtained by this method has oil evenly distributed in the starch without obvious agglomeration, and the binding is stable. It is not easy to flow out during storage. The prepared batter has no obvious oil droplets or lumps, and the coating is even during subsequent frying.

[0040] The oil-processed starch prepared by this invention can be used directly as a dusting flour or coating powder, or dissolved in water and used as a batter for coating fried foods.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] (1) This invention constructs a water activity gradient within starch granules through a water balancing step, increasing the surface starch moisture content and relaxing the molecular chains, thus exposing more amylose binding sites. Simultaneously, the water gradient-driven molecular migration promotes the migration of phospholipid-fatty acid molecules into the starch interior along the water diffusion path. The amphiphilic structure of phospholipids can form hydrogen bonds with starch hydroxyl groups; the hydrophobic segments of fatty acids provide specific sites for subsequent oil binding. Based on this, when oils are added in a co-electrode manner, the mixture of medium-chain triglycerides and high-oleic sunflower seed oil forms a stable bound oil layer with starch through the linkage of phospholipid-fatty acid, rather than simple physical adsorption. The gradient dehydration process, through a dehydration method that is fast at first and then slow, allows the surface oil to spread more evenly during the outward migration of water, while preventing the oil from being squeezed out during the drying process.

[0043] (2) The oil-processed starch prepared by this invention has oil evenly distributed in the starch without obvious agglomeration, and the binding is stable. It is not easy to leak out during storage. The prepared batter has no obvious oil droplets or lumps, and the coating is uniform during subsequent frying. This oil-processed starch has a low oil leakage rate and frying oil absorption rate, and excellent batter adhesion. After 7 days of accelerated storage, the oil leakage rate is as low as 4%-5%, indicating that the oil binding is stable and not easy to migrate. The frying oil absorption rate is controlled at 22%-24%, which effectively reduces the total fat content of fried foods. The batter adhesion rate reaches 62%-65%, which has good adhesion function. Detailed Implementation

[0044] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described.

[0045] Example 1

[0046] A method for preparing starch from oil processing:

[0047] (1) Moisture balance: Place 100g (on a dry basis) of corn starch in an environment of 25 ℃ and 78% relative humidity for 0.8 h to balance the moisture balance starch.

[0048] (2) Phospholipid-fatty acid co-spraying: Dissolve 1.0g lecithin, 1.6g stearic acid and 0.4g oleic acid in 14g 65% ethanol aqueous solution, and heat and stir in a water bath at 52℃ until completely dissolved;

[0049] The balanced starch was placed in a spray granulator, and the stirring was turned on at a speed of 125 r / min. The system temperature was maintained at 45℃. The spray liquid was evenly sprayed onto the starch surface through the atomizing nozzle for 30 min. After spraying, stirring was continued for 5 min to ensure that the phospholipids and fatty acids were evenly distributed on the starch surface.

[0050] (3) Addition of oils and fats:

[0051] Mix 0.5 g of medium-chain triglycerides with 1.65 g of high-oleic sunflower seed oil, preheat in a 38 ℃ water bath until completely clear and transparent, and add the oil mixture evenly to the activated starch under stirring through an atomizing nozzle for 14.5 min, maintaining the material temperature at 52 ℃ and the stirring speed at 90 r / min. After the addition is completed, continue stirring for 5 min to ensure uniform coating of the oil and obtain oil-based composite starch.

[0052] In the fatty acid composition of the medium-chain triglycerides, saturated fatty acids with 8 and 10 carbon atoms account for ≥90 wt%.

[0053] (4) Gradient dehydration: The oil-starch composite is subjected to a two-stage dehydration process;

[0054] First stage: Temperature 40 ℃, wind speed 1.2 m / s, dehydration for 30 min, continuous turning, turning frequency 10 times / min;

[0055] Second stage: temperature 45 ℃, wind speed 0.7 m / s, dehydration for 60 min, intermittent turning, turning frequency 4 times / min;

[0056] The moisture content of the starch after dehydration is 10.1%.

[0057] (5) Maturation:

[0058] The dehydrated starch was placed in a sealed container and allowed to mature at 44°C for 20 hours to obtain oil-processed starch.

[0059] Example 2

[0060] A method for preparing starch from oil processing:

[0061] (1) Moisture balance: Place 100g (dry basis) of corn starch in an environment of 23 ℃ and 75% relative humidity for 0.9 h to obtain moisture-balanced starch.

[0062] (2) Phospholipid-fatty acid co-spraying: Dissolve 0.8 g lecithin, 1.35 g stearic acid and 0.15 g oleic acid in 12 g 60% ethanol aqueous solution, and heat and stir in a 50 ℃ water bath until completely dissolved;

[0063] The balanced starch was placed in a spray granulator, the stirring was turned on at 100 r / min, the system temperature was maintained at 43℃, and the spray liquid was evenly sprayed onto the starch surface through the atomizing nozzle for 35 min. After the spraying was completed, stirring was continued for 6 min to ensure that the phospholipids and fatty acids were evenly distributed on the starch surface.

[0064] (3) Addition of oils and fats:

[0065] Mix 0.4 g of medium-chain triglycerides with 1.5 g of high-oleic sunflower seed oil, preheat in a 35 ℃ water bath until completely clear and transparent, and add the oil mixture evenly to the activated starch under stirring through an atomizing nozzle for 16 min. Maintain the material temperature at 50 ℃ and the stirring speed at 80 r / min. After the addition is completed, continue stirring for 6 min to ensure that the oil is evenly coated, thus obtaining the oil-coated starch.

[0066] In the fatty acid composition of the medium-chain triglycerides, saturated fatty acids with 8 and 10 carbon atoms account for ≥90 wt%.

[0067] (4) Gradient dehydration: The oil-starch composite is subjected to a two-stage dehydration process;

[0068] First stage: temperature 38 ℃, wind speed 1.1 m / s, dehydration for 32 min, continuous turning, turning frequency 8 times / min;

[0069] Second stage: temperature 43 ℃, wind speed 0.6 m / s, dehydration for 65 min, intermittent turning, turning frequency 3 times / min;

[0070] The moisture content of the starch after dehydration is 11.8%.

[0071] (5) Maturation:

[0072] The dehydrated starch was placed in a sealed container and allowed to mature at 42 ℃ for 22 h to obtain oil-processed starch.

[0073] Example 3

[0074] A method for preparing starch from oil processing:

[0075] (1) Moisture balance: Place 100g (dry basis) of corn starch in an environment of 27 ℃ and 80% relative humidity for 0.7 h to obtain moisture-balanced starch.

[0076] (2) Phospholipid-fatty acid co-spraying: Dissolve 1.2 g lecithin, 2.0 g stearic acid and 0.5 g oleic acid in 16 g 70% ethanol aqueous solution, and heat and stir in a 55 ℃ water bath until completely dissolved;

[0077] The balanced starch was placed in a spray granulator, the stirring was turned on at 150 r / min, the system temperature was maintained at 47℃, and the spray liquid was evenly sprayed onto the starch surface through the atomizing nozzle for 25 min. After the spraying was completed, stirring was continued for 4 min to ensure that the phospholipids and fatty acids were evenly distributed on the starch surface.

[0078] (3) Addition of oils and fats:

[0079] Mix 0.6 g of medium-chain triglycerides with 1.8 g of high-oleic sunflower seed oil, preheat in a 40 ℃ water bath until completely clear and transparent, and add the oil mixture evenly to the activated starch under stirring through an atomizing nozzle for 13 min. Maintain the material temperature at 55 ℃ and the stirring speed at 100 r / min. After the addition is completed, continue stirring for 4 min to ensure that the oil is evenly coated, thus obtaining the oil-coated starch.

[0080] In the fatty acid composition of the medium-chain triglycerides, saturated fatty acids with 8 and 10 carbon atoms account for ≥90 wt%.

[0081] (4) Gradient dehydration: The oil-starch composite is subjected to a two-stage dehydration process;

[0082] First stage: temperature 42 ℃, wind speed 1.3 m / s, dehydration for 28 min, continuous turning, turning frequency 12 times / min;

[0083] Second stage: temperature 47 ℃, wind speed 0.8 m / s, dehydration for 55 min, intermittent turning, turning frequency 5 times / min;

[0084] The moisture content of the starch after dehydration is 8.5%.

[0085] (5) Maturation:

[0086] The dehydrated starch was placed in a sealed container and allowed to mature at 46 ℃ for 18 h to obtain oil-processed starch.

[0087] Comparative Example 1

[0088] Comparative Example 1 uses the oil-processed starch preparation method described in Example 1, except that the moisture balancing step is omitted, while the other steps are the same.

[0089] Comparative Example 2

[0090] Comparative Example 2 uses the oil-processed starch preparation method described in Example 1, except that the phospholipid-fatty acid co-spraying step is omitted, while the other steps are the same.

[0091] Comparative Example 3

[0092] Comparative Example 3 uses the oil-processed starch preparation method described in Example 1. The difference is that in the phospholipid-fatty acid co-spraying step, the addition of lecithin is omitted and replaced with fatty acids of equal mass, that is, 0.72g of stearic acid and 0.08g of oleic acid are used instead. The remaining steps are the same.

[0093] Comparative Example 4

[0094] Comparative Example 4 uses the oil-processed starch preparation method described in Example 1, except that in the oil co-melting addition step, medium-chain triglycerides are omitted and an equal mass of high-oleic sunflower seed oil is used instead of medium-chain triglycerides, while the other steps are the same.

[0095] Experimental Example 1

[0096] For the oil-processed starches prepared by the methods of Examples 1-3 and Comparative Examples 1-4, the oil exudation rate was tested. The test method was as follows: 10 g of sample was placed in a filter paper tube and stored at 40°C and 75% RH for 7 days. The weight gain of the filter paper was then measured. The exudation rate (%) = (weight of exuded oil / total weight of sample oil) × 100%, where the total weight of sample oil is the total amount of medium-chain triglycerides and high-oleic sunflower seed oil added during the preparation of oil-processed starch. The test results are shown in Table 1.

[0097] Table 1

[0098]

[0099] Experimental Example 2

[0100] The oil-processed starches prepared by the methods of Examples 1-3 and Comparative Examples 1-4 were tested for oil absorption rate after frying through frying experiments and Soxhlet extraction. Specifically, samples were made into uniformly sized coated chicken pieces, and the oil-processed starch to be tested was prepared into a 35wt% starch paste. After uniformly coating the samples with the paste, they were fried at 180℃ for 3 min. The content of free oil in the unfried oil-processed starch was determined by Soxhlet extraction according to GB 5009.6-2025 "National Food Safety Standard - Determination of Fat in Food", and recorded as W0. The content of free oil in the pulverized fried sample was then determined and recorded as W1. The oil absorption rate after frying was calculated as (W1-W0) / m, where m is the mass of the coated starch in the sample before frying. The test results are shown in Table 2.

[0101] Table 2

[0102]

[0103] Experimental Example 3

[0104] For the oil-processed starches prepared by the methods of Examples 1-3 and Comparative Examples 1-4, the adhesion of the batter was tested by weighing method. Specifically, fresh or thawed skinless chicken breasts with consistent size, shape and moisture content were selected. The weight of the meat pieces before coating was weighed (m0). The oil-processed starch to be tested was prepared into a starch paste of 35wt%. The sample was coated evenly with the paste and then weighed (m1). The adhesion rate (%) = (m1-m0) / m1×100%. The test results are shown in Table 3.

[0105] Table 3

[0106]

[0107] Comparative Example 1, omitting the moisture balance step, showed a seepage rate of 12%, an oil absorption rate of 32% during frying, and a batter adhesion rate of 51%. The core function of the moisture balance step in this invention is to construct a water activity gradient within the starch granules. As the surface moisture of the starch increases, the molecular chains relax, exposing more amylose binding sites. Simultaneously, the moisture gradient influences the chemical potential distribution in the system, driving the directional migration of phospholipid-fatty acid molecules into the starch interior, promoting the formation of starch-lipid complexes. When this step is omitted, the starch granules are in a dry and dense state, making it difficult for phospholipid-fatty acid molecules to penetrate into the interior. Most remain in the intergranular spaces or on the surface, significantly reducing the complexation efficiency between fatty acids and starch. This means that subsequently added oils cannot effectively bind through phospholipid-fatty acid bridging; most oils are only physically adsorbed onto the starch surface. Physically adsorbed oils are prone to seepage during storage and are easily replaced by hot oil during frying, or trigger further oil seepage. Furthermore, free oil on the surface hinders batter adhesion, resulting in a decreased adhesion rate.

[0108] Comparative Example 2 omitted the phospholipid-fatty acid co-spraying step, resulting in an oil penetration rate of 25%, an oil absorption rate of 38% during frying, and a batter adhesion rate of 46%. In Comparative Example 2, the oil directly contacted the unmodified starch surface. The starch surface is rich in hydroxyl groups and is strongly hydrophilic, making it unable to form a strong interaction with the hydrophobic oil. The added oil was physically adsorbed onto the starch surface in a free state. During accelerated storage, the free oil easily migrated and penetrated, with a penetration rate as high as 25%. During frying, almost all of the free oil was replaced by the hot oil. However, the starch surface is hydrophilic, and during frying, it would absorb a large amount of new oil from the oil pan, resulting in the highest oil absorption rate (38%). A large amount of free oil on the surface formed an oil film, preventing the batter from adhering effectively, resulting in the lowest adhesion rate.

[0109] Comparative Example 3, omitting lecithin and using only fatty acids, showed an oil leakage rate of 10%, an oil absorption rate of 29% during frying, and a batter adhesion rate of 60%. Comparative Example 3, by retaining fatty acids, formed a "starch-fatty acid" complex, thus exhibiting superior leakage, oil absorption, and adhesion rates compared to Comparative Example 2, which completely omitted lecithin and fatty acids. However, the absence of lecithin resulted in the loss of its amphiphilic structure's "anchoring" effect and its "bridging" function with subsequent oils, leading to decreased oil-binding stability. This indicates a synergistic effect between lecithin and fatty acids in achieving oil-binding stability.

[0110] Comparative Example 4 omitted medium-chain triglycerides (MCTs) and used only high-oleic sunflower oil. The oil seepage rate was 7%, the frying oil absorption rate was 27%, and the batter adhesion rate was 63%. MCTs have low viscosity and good compatibility with fatty acids and phospholipids, which helps the oil mixture spread evenly on the starch surface. Without MCTs, the compatibility between the oil mixture and fatty acids decreased, leading to uneven distribution during spreading, such as localized over-thickness or gaps, resulting in a slight decrease in oil-fat binding stability. However, this comparative example still retained the phospholipid-fatty acid anchoring effect and the oil-fat complexing mechanism, thus its effect was better than other comparative examples, indicating that MCTs mainly play an auxiliary spreading role.

[0111] Starch dispersion state

[0112] The oil-processed starch granules prepared in Examples 1-3 are loose, with oil evenly distributed in the starch without obvious agglomeration and stable binding. The prepared batter has no obvious oil droplets or lumps, and the coating is uniform during subsequent frying. The oil permeation rate is 4-5%, the oil absorption rate during frying is 22-24%, and the batter adhesion rate is 62-65%, indicating that the oil is evenly dispersed, firmly bound to the starch, has a low proportion of free oil, minimal permeation during storage, and is not easily replaced by hot oil or additionally absorbed during frying.

[0113] The processed starch prepared in Comparative Example 1 had a slight oily sheen in some areas and a slight stickiness between the particles; the surface of the prepared batter showed fine oil droplets; its oil seepage rate was 12%, its oil absorption rate during frying was 32%, and its batter adhesion rate was 51%, indicating that the lack of moisture gradient led to insufficient phospholipid-fatty acid penetration, and the oil was mainly adsorbed by physical means, making it easy to seep out during storage, easy to absorb oil during frying, and difficult to adhere to the batter.

[0114] The oil-processed starch prepared in Comparative Example 2 had a noticeably oily surface, with heavy adhesion between particles. Tiny oil droplets formed by oil precipitation were visible in some areas, and it was prone to clumping when sieved. The prepared batter had many oil droplets on its surface, and the batter slid off quickly when coated, making it difficult to coat the food surface evenly. Its oil seepage rate was 25%, frying oil absorption rate was 38%, and batter adhesion rate was 46%, indicating that the unmodified hydrophilic starch could not form an effective bond with the oil, the oil was completely free, and it had serious migration during storage, the highest frying oil absorption, and the worst adhesion.

[0115] The appearance of the oil-processed starch prepared in Comparative Example 3 was similar to that of the Example. The granules were generally loose and the surface had no obvious oil sheen, but there were occasional slight oil stains in some areas. There was basically no adhesion between the granules. The prepared batter had fewer oil droplets on the surface and the coating uniformity was acceptable. Its oil seepage rate was 10%, the frying oil absorption rate was 29%, and the batter adhesion rate was 60%, indicating that fatty acids could form some starch-fatty acid complexes. However, after the loss of the amphiphilic anchoring and bridging function of lecithin, the oil binding stability was lower than that of the Example.

[0116] The oil-processed starch granules prepared in Comparative Example 4 were generally loose, but the surface gloss was slightly higher than that of the Example. Some areas showed slightly uneven oil distribution, and there was occasional slight adhesion between the granules. The prepared batter had fewer oil droplets on the surface, better coating uniformity, and moderate viscosity. Its oil exudation rate was 7%, frying oil absorption rate was 27%, and batter adhesion rate was 63%, indicating that medium-chain triglycerides mainly played an auxiliary spreading role. When they were absent, the uniformity of oil distribution decreased slightly, but the phospholipid-fatty acid anchoring mechanism still made the effect better than other comparative examples.

[0117] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing starch from oil processing, characterized in that, The preparation method includes the following steps: balancing moisture, co-spraying phospholipids and fatty acids, co-adding oils and fats, gradient dehydration, and maturation. The method for balancing moisture is to place starch in an environment with a relative humidity of 75%-80% to equilibrate it, thereby obtaining moisture-balanced starch. The method of co-spraying phospholipids and fatty acids is as follows: lecithin and fatty acids are dissolved in an ethanol-water solution at 50-55 ℃, and atomized and sprayed onto the starch surface for 25-35 min. During the spraying process, the system temperature is controlled at 43-47 ℃ under stirring conditions. After spraying, stirring is continued for 4-6 min to obtain activated starch. The fatty acid is a mixture of stearic acid and oleic acid in a mass ratio of 8:1.8-2.2; The method for adding the oil and fat is as follows: medium-chain triglycerides are mixed with high-oleic sunflower seed oil and added to activated starch under stirring conditions by atomization. The addition time is 13-16 min, the temperature is maintained at 50-55 ℃, and stirring is continued for 4-6 min after addition to obtain oil-fat composite starch.

2. The method for preparing starch from oil processing according to claim 1, characterized in that, In the moisture balancing step, the temperature is 23-27 ℃ and the balancing time is 0.7-0.9 h.

3. The method for preparing starch from oil processing according to claim 1, characterized in that, In the phospholipid-fatty acid co-spraying step The mass ratio of the lecithin, fatty acids, aqueous ethanol solution to starch dry basis is 0.8-1.2:1.5-2.5:12-16:100; The starch dry basis refers to the absolute dry weight of starch.

4. The method for preparing starch from oil processing according to claim 1, characterized in that, In the phospholipid-fatty acid co-spraying step The stirring speed is 100-150 r / min; The concentration of the ethanol aqueous solution is 60%-70%.

5. The method for preparing starch from oil processing according to claim 4, characterized in that, In the step of adding oils and fats together In the fatty acid composition of the medium-chain triglycerides, the proportion of saturated fatty acids with 8 and 10 carbon atoms is ≥90wt%. The mass ratio of the medium-chain triglycerides, high-oleic sunflower seed oil, and starch (dry basis) is 0.4-0.6:1.5-1.8:

100. The high-oleic sunflower seed oil has an oleic acid content of >75%.

6. The method for preparing starch from oil processing according to claim 1, characterized in that, In the step of adding oils and fats together The medium-chain triglycerides and high-oleic sunflower seed oil are mixed at a temperature of 35-40 ℃; The stirring speed is 80-100 r / min.

7. The method for preparing starch from oil processing according to claim 1, characterized in that, The gradient dehydration method involves a two-stage dehydration process. In the first stage, the temperature is controlled at 38-42 ℃ and the wind speed at 1.1-1.3 m / s for 28-32 min, during which the material is turned over to remove surface free moisture. In the second stage, the temperature is controlled at 43-47 ℃ and the wind speed at 0.6-0.8 m / s for 55-65 min, during which the material is turned over to obtain dehydrated starch.

8. The method for preparing starch from oil processing according to claim 7, characterized in that, In the gradient dewatering step, the frequency of turning the material in the first stage is 8-12 times / min; The frequency of turning the material in the second stage is 3-5 times / min.

9. The method for preparing starch from oil processing according to claim 1, characterized in that, The maturation method involves placing the dehydrated starch in a sealed environment, controlling the temperature at 42-46 ℃, and allowing it to mature for 18-22 hours to finally obtain oil-processed starch.

10. Oil-processed starch prepared by the method according to any one of claims 1-9.

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