Combined treatment method for improving digestibility of cassava and application thereof

Abstract

The invention provides a combined treatment method for improving digestibility of cassava, which comprises the following steps: A) pretreating a cassava sample, and then carrying out heat treatment, drying, grinding and sieving to obtain cassava flour; the heat treatment comprises water boiling, steaming and frying; b) mixing and degreasing tapioca flour with petroleum ether to obtain degreased tapioca flour; and C) mixing the degreased tapioca flour with a buffer solution, performing enzymolysis, performing enzyme deactivation, performing centrifugation, performing washing, performing drying, performing grinding, and performing sieving so as to obtain the tapioca flour. On the basis of different heat treatments, a reagent and an enzyme preparation are selected to remove related components of the tapioca flour, the digestibility of the prepared tapioca flour presents different digestion change difference trends by utilizing a combined treatment method, the content of resistant starch in the tapioca flour subjected to steaming and deep-frying treatment is remarkably increased, and the content of the resistant starch in the tapioca flour subjected to steaming and deep-frying treatment is remarkably increased. And the tapioca flour subjected to water boiling treatment can significantly improve the content of fast-digestible starch, and shows different properties and qualities. Compared with physical and chemical means, the method has the advantage that the content of resistant starch of cassava after heat treatment is obviously changed.

Description

Technical Field

[0001] The invention relates to the technical field of functional additives, in particular to a combined processing method for improving cassava digestibility and application thereof. Background Art

[0002] Cassava (Manihot esculenta Crantz), belonging to the genus Manihot in the Euphorbiaceae family, is widely planted in more than 100 countries and regions in Africa, America and Asia for its drought and barrenness resistance. It has become one of the three major tuber crops, especially in tropical regions, where it ranks third among food crops and sixth worldwide, and is known as the "king of starch". Since it was introduced to China from Southeast Asia (i.e. Malaysia) in 1820, cassava is now mainly distributed in provinces such as Guangxi, Guangdong, Hainan, Yunnan, Fujian, Guizhou, Hunan and Jiangxi.

[0003] Cassava, with its excellent photosynthesis efficiency, produces far more food energy per unit area under the same conditions than classic crops such as rice, wheat, corn and sorghum, making it an important food cornerstone for the survival of nearly 700 million people in Africa, South America and Southeast Asia. However, this valuable resource also comes with challenges: the natural hydrocyanic acid contained in it must be safely removed through heat processing, but the high temperature in this process inevitably leads to a significant reduction in resistant starch (RS), a change that is directly related to the regulation of postprandial blood sugar. The reduction of resistant starch means that cassava food may quickly increase blood sugar levels after ingestion, which is undoubtedly a difficult problem that needs to be overcome for modern consumers who pursue healthy diets and prevent chronic diseases.

[0004] Given the key role of delaying the rise of postprandial blood sugar in the prevention and management of diabetes, it is particularly important to develop heat-treated cassava foods with a low glycemic index (GI). Such foods can not only effectively control postprandial blood sugar fluctuations and insulin secretion levels, but also improve insulin resistance and reduce the burden on the blood sugar homeostasis regulatory system, thus showing great potential in preventing and treating chronic diseases caused by poor eating habits. Therefore, studying how to improve postprandial blood sugar production in cassava after different heat treatments has important nutritional significance.

[0005] Traditionally, cassava is processed by steaming, frying, etc., which will produce a large amount of postprandial blood sugar. At present, the preparation methods to reduce the glycemic index by increasing the content of resistant starch mostly use physical processes (moist heat treatment, annealing, etc.) or chemical methods (phosphorylation, oxidation, etc.). Although physical processes are safe and environmentally friendly, the process is complicated and time-consuming; while chemical methods are easy to operate and can effectively change the properties of resistant starch, they may introduce exogenous substances, and in actual operations, they often lead to increased costs and waste of human resources due to complex equipment and high requirements for condition optimization. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a combined processing method for improving the digestibility of cassava. The digestibility of cassava flour prepared by the present invention is significantly different, the digestibility of boiled cassava flour increases, and the digestibility of steamed and fried cassava flour decreases.

[0007] The present invention provides a combined processing method for improving the digestibility of cassava, comprising:

[0008] A) pre-treating the cassava sample, heat-treating, drying, grinding, and sieving to obtain cassava flour; the heat treatment includes boiling, steaming, and frying;

[0009] B) using petroleum ether to mix and defat cassava flour to obtain defatted cassava flour;

[0010] C) Mixing defatted cassava flour and buffer, enzymolyzing, inactivating the enzyme, centrifuging, washing, drying, grinding and sieving to obtain the product.

[0011] The combined treatment method for improving cassava digestibility provided by the present invention first pre-treats the cassava sample.

[0012] In some specific embodiments, the cassava pretreatment includes: selecting fresh cassava with a middle diameter of 3 to 6 cm, removing the outer skin and inner skin, cutting off the head and tail, taking the middle section, washing and cutting into cylinders with a thickness of 1 to 5 cm.

[0013] The processing method for improving the digestibility of cassava provided by the invention first selects cassava with uniform shape and size and gelatinizes them in a steamer or an electric fryer.

[0014] Specifically, the cassava of uniform shape and size, i.e., cassava with a middle diameter of 3 to 6 cm, is cut into a cylinder with a thickness of 1 to 5 cm; preferably, cassava with a middle diameter of 4 to 5 cm is cut into a cylinder with a thickness of 2 to 3 cm. In some preferred embodiments, cassava with a middle diameter of 5 cm can be selected and cut into 2 cm cassava pieces.

[0015] The steaming method of the present invention comprises: the ratio of the mass of the cassava sample to the volume of distilled water is 1: (4-8) g: 1000-2000 mL; the steaming time is 20-35 min;

[0016] In some specific embodiments, the ratio of the mass of the cassava sample to the volume of distilled water is 1:(4-6)g:1000-1500mL; the steaming time is 20-30min;

[0017] In some specific embodiments, the frying includes: the ratio of the mass of the cassava sample to the volume of the edible oil is 1: (8-12) g: 2-3 L; the frying temperature is 150-180° C.; and the frying time is 20-35 min.

[0018] In some specific embodiments, the frying includes: the ratio of the mass of the cassava sample to the volume of the edible oil is 1: (8-10) g: 2-2.5 L; the frying temperature is 170-180° C.; and the frying time is 20-30 min.

[0019] After heat treatment, the cassava flour is obtained by drying, grinding and sieving.

[0020] Preferably, the drying is carried out at 40-50° C. for 24-48 hours, and the dried cassava samples are ground by a multifunctional grinder and passed through a 100-150 μm pore size mesh sieve.

[0021] In some specific embodiments, the heat-treated sample is dried in an electric constant temperature blast drying oven (45° C., 48 h) until the moisture content is ≤10%. The dried cassava is ground by a multifunctional grinder and passed through a 150 μm mesh sieve, sealed in a plastic bag, and stored at room temperature away from light.

[0022] The cassava flour is mixed with petroleum ether and defatted to obtain defatted cassava flour.

[0023] In some specific embodiments, cassava flour and petroleum ether are mixed, stirred, and centrifuged, and the process is repeated three times;

[0024] The mass volume ratio of the cassava flour and petroleum ether is 1: (8-16) g: 200-400 mL; the stirring time is 1-4 h, specifically 1 h, 2 h, 3 h or 4 h; the centrifugal parameters include: the rotation speed is 4000-6000 r / min, specifically 4000 r / min, 5000 r / min 6000 r / min; centrifugation at 4°C for 10-15 min, specifically 10 min, 11 min, 12 min, 13 min, 14 min or 15 min.

[0025] The defatted cassava flour was mixed with a buffer solution and subjected to enzymatic hydrolysis.

[0026] In some specific embodiments, the buffer is sodium acetate buffer; the concentration of the buffer is 0.1 M, pH = 5.2;

[0027] The defatted cassava flour and buffer solution are mixed in a mass ratio of 1:(10-15) g:40-60 mL.

[0028] In some specific embodiments, the enzymes include cellulase, hemicellulase and pectinase; wherein the added amounts of cellulase, hemicellulase and pectinase are (20-30U): (20-30U): (20-30U).

[0029] In a specific embodiment, the addition amount of cellulase, hemicellulase and pectinase is 20U:20U:20U;

[0030] In a specific embodiment, the addition amount of cellulase, hemicellulase and pectinase is 25U:25U:25U;

[0031] In a specific embodiment, the added amounts of cellulase, hemicellulase and pectinase are 30U:30U:30U.

[0032] According to the present invention, the enzymatic activity of the cellulase is 50U / mg, and the added amount is 20-30U; the enzymatic activity of the hemicellulase is 6U / mg, and the added amount is 20-30U; the enzymatic activity of the pectinase is 30U / mg, and the added amount is 20-30U.

[0033] The enzymatic hydrolysis parameters of the present invention include: incubation at 37° C. in a water bath shaker for 40 to 60 minutes; specifically, it can be 40 minutes, 45 minutes, 50 minutes, 55 minutes or 60 minutes; or a range between any two of the above.

[0034] The enzyme is inactivated by enzymolysis, followed by centrifugation, washing, drying, grinding and sieving. The drying, grinding and sieving include: placing at 40-50°C for 24-48 hours; crushing for 1-2 minutes; and sieving through a 100-150 μm pore size mesh screen.

[0035] The enzyme inactivation method of the present invention comprises: using ethanol to inactivate; preferably adding 140-180 mL of ethanol to inactivate the reaction.

[0036] The centrifugation includes: centrifugation at 10000 r / min for 30 to 50 minutes at 4°C; and the washing includes: washing with 80% ethanol for 2 to 3 times.

[0037] Then the treated cassava flour is dried and sieved; the drying of the present invention is placed in an electric constant temperature air drying oven at 40-50° C. for 24-48 hours, and the dried cassava samples are ground by a multifunctional grinder through a 100-150 μm aperture mesh sieve, sealed in a plastic bag, and stored at room temperature away from light.

[0038] The above-mentioned heat treatment gelatinization, defatting treatment and defatting-removal of non-starch polysaccharide treatment of the present invention belong to an overall technical solution, and they are functionally mutually supportive. There are technical features of interactive relationship, and the above-mentioned synergistic cooperation can solve the technical problems of the present invention and achieve the technical effects of the present invention, which is the key to improving the digestibility of cassava.

[0039] The present invention provides a cassava with improved digestibility, which is prepared by the preparation method described in any one of the above technical solutions.

[0040] The present invention provides application of any one of the above-mentioned preparation methods in reducing the digestibility of cassava flour.

[0041] The method of reducing the digestibility of cassava flour of the present invention comprises increasing the content of resistant starch, reducing postprandial blood sugar and reducing the postprandial glycemic index.

[0042] The present invention is beneficial to reducing the postprandial glycemic index in steaming and frying heat treatments, wherein the frying treatment reduces the glycemic index the most.

[0043] The method adopted by the present invention is simple and easy to operate, can effectively change the resistant starch content of cassava flour after steaming and frying, has the effect of reducing blood sugar and insulin response, is suitable for obese and diabetic patients to eat, and at the same time improves the blood sugar generation rate of cassava flour after boiling, is more suitable for quickly replenishing human energy, and is suitable as an additive to change the processing characteristics of food.

[0044] The present invention also provides a combined processing method for improving the digestibility of cassava, comprising:

[0045] A) pre-treating the cassava sample, heat-treating, drying, grinding, and sieving to obtain cassava flour; the heat treatment includes boiling, steaming, and frying;

[0046] B) using petroleum ether to mix and defat cassava flour to obtain defatted cassava flour;

[0047] C) Mixing defatted cassava flour and buffer, enzymolyzing, inactivating the enzyme, centrifuging, washing and drying to obtain the product.

[0048] The combined treatment method for improving cassava digestibility provided by the present invention first pre-treats the cassava sample.

[0049] In some specific embodiments, the cassava pretreatment includes: selecting fresh cassava with a middle diameter of 3 to 6 cm, removing the outer skin and inner skin, cutting off the head and tail, taking the middle section, washing and cutting into cylinders with a thickness of 1 to 5 cm.

[0050] The processing method for improving the digestibility of cassava provided by the invention first selects cassava with uniform shape and size and gelatinizes them in a steamer or an electric fryer.

[0051] Specifically, the cassava of uniform shape and size, i.e., cassava with a middle diameter of 3 to 6 cm, is cut into a cylinder with a thickness of 1 to 5 cm; preferably, cassava with a middle diameter of 4 to 5 cm is cut into a cylinder with a thickness of 2 to 3 cm. In some preferred embodiments, cassava with a middle diameter of 5 cm can be selected and cut into 2 cm cassava pieces.

[0052] In some specific embodiments, the boiling treatment includes: the ratio of the mass of the cassava sample to the volume of distilled water is 1: (10-16) g: 2500-4000 mL; and the boiling time is 20-35 min.

[0053] In some specific embodiments, the boiling treatment includes: the ratio of the mass of the cassava sample to the volume of distilled water is 1: (10-12) g: 2500-3000 mL; and the boiling time is 20-30 min.

[0054] After heat treatment, the cassava flour is obtained by drying, grinding and sieving.

[0055] Preferably, the drying is carried out at 40-50° C. for 24-48 hours, and the dried cassava samples are ground by a multifunctional grinder and passed through a 100-150 μm pore size mesh sieve.

[0056] In some specific embodiments, the heat-treated sample is dried in an electric constant temperature blast drying oven (45° C., 48 h) until the moisture content is ≤10%. The dried cassava is ground by a multifunctional grinder and passed through a 150 μm mesh sieve, sealed in a plastic bag, and stored at room temperature away from light.

[0057] The cassava flour is mixed with petroleum ether and defatted to obtain defatted cassava flour.

[0058] In some specific embodiments, cassava flour and petroleum ether are mixed, stirred, and centrifuged, and the process is repeated three times;

[0059] The mass volume ratio of the cassava flour and petroleum ether is 1: (8-16) g: 200-400 mL; the stirring time is 1-4 h, specifically 1 h, 2 h, 3 h or 4 h; the centrifugal parameters include: the rotation speed is 4000-6000 r / min, specifically 4000 r / min, 5000 r / min 6000 r / min; centrifugation at 4°C for 10-15 min, specifically 10 min, 11 min, 12 min, 13 min, 14 min or 15 min.

[0060] The defatted cassava flour was mixed with a buffer solution and subjected to enzymatic hydrolysis.

[0061] In some specific embodiments, the buffer is sodium acetate buffer; the concentration of the buffer is 0.1 M, pH = 5.2;

[0062] The defatted cassava flour and buffer solution are mixed in a mass ratio of 1:(10-15) g:40-60 mL.

[0063] In some specific embodiments, the enzymes include cellulase, hemicellulase and pectinase; wherein the added amounts of cellulase, hemicellulase and pectinase are (20-30U): (20-30U): (20-30U).

[0064] In a specific embodiment, the addition amount of cellulase, hemicellulase and pectinase is 20U:20U:20U;

[0065] In a specific embodiment, the addition amount of cellulase, hemicellulase and pectinase is 25U:25U:25U;

[0066] In a specific embodiment, the added amounts of cellulase, hemicellulase and pectinase are 30U:30U:30U.

[0067] According to the present invention, the enzymatic activity of the cellulase is 50U / mg, and the added amount is 20-30U; the enzymatic activity of the hemicellulase is 6U / mg, and the added amount is 20-30U; the enzymatic activity of the pectinase is 30U / mg, and the added amount is 20-30U.

[0068] The enzymatic hydrolysis parameters of the present invention include: incubation at 37° C. in a water bath shaker for 40 to 60 minutes; specifically, it can be 40 minutes, 45 minutes, 50 minutes, 55 minutes or 60 minutes; or a range between any two of the above.

[0069] The enzyme is inactivated by enzymolysis, followed by centrifugation, washing, drying, grinding and sieving.

[0070] The enzyme inactivation method of the present invention comprises: using ethanol to inactivate; preferably adding 140-180 mL of ethanol to inactivate the reaction.

[0071] The centrifugation includes: centrifugation at 10000 r / min for 30 to 50 minutes at 4°C; and the washing includes: washing with 80% ethanol for 2 to 3 times.

[0072] Then the treated cassava flour is dried and sieved; the drying of the present invention is placed in an electric constant temperature air drying oven at 40-50° C. for 24-48 hours, and the dried cassava samples are ground by a multifunctional grinder through a 100-150 μm aperture mesh sieve, sealed in a plastic bag, and stored at room temperature away from light.

[0073] The present invention provides a cassava with improved digestibility, which is prepared by the preparation method described in any one of the above technical solutions.

[0074] The present invention provides application of the preparation method described in any one of the above technical solutions in improving the digestibility of cassava flour.

[0075] The present invention improves the blood sugar generation rate of cassava flour after boiling, is more suitable for quickly replenishing human energy, and is suitable for being used as an additive to change the processing characteristics of food.

[0076] The steamed cassava flour and fried cassava flour treated with defatted and non-starch polysaccharide removed prepared by the present invention have resistant starch contents of 32.53±0.66% and 27.02±2.52% and glycemic indexes of 62.13±0.50 and 67.83±0.31, respectively, while the resistant starch content in the boiled cassava flour treated with defatted and non-starch polysaccharide removed is 21.04±0.13% and the glycemic index is 75.23±0.60. The present invention provides a treatment method for improving cassava digestibility, comprising the following steps: A) boiling, steaming and frying cassava samples, drying, grinding and sieving the heat-treated samples to obtain heat-treated cassava flour; B) mixing the heat-treated cassava flour obtained with petroleum ether, stirring and centrifuging, repeating three times to obtain defatted cassava flour; C) suspending the defatted cassava flour in sodium acetate buffer, adding cellulase, hemicellulase and pectinase, and putting it into a centrifuge bottle. The reaction mixture is incubated in a water bath shaker. The reaction is inactivated by adding ethanol, and the slurry is centrifuged and washed with ethanol. The treated cassava flour is dried and sieved to obtain. In view of the existing treatment methods for improving the digestibility of cassava, the present invention selects reagents and enzyme preparations to remove related components from cassava flour on the basis of different heat treatments, and uses a combined treatment method to make the digestibility of the prepared cassava flour present different digestion change trends. The cassava flour treated with steaming and frying significantly increases the content of resistant starch and reduces postprandial blood sugar, while the cassava flour treated with boiling significantly increases the content of fast-digestible starch and improves postprandial blood sugar, showing different performance and quality, and in some aspects even better than the existing level. Compared with physical processes and chemical means, the present invention significantly changes the resistant starch content and glycemic index of cassava flour after heat treatment on the basis of cost saving, is simple to operate, low in cost, and is suitable for large-scale production.

[0077] The invention provides a combined treatment method for improving the digestibility of cassava, comprising: A) pre-treating a cassava sample, heat-treating, drying, grinding, and sieving to obtain cassava flour; the heat treatment includes boiling, steaming, and frying; B) mixing cassava flour with petroleum ether to defat it, to obtain defatted cassava flour; C) mixing the defatted cassava flour with a buffer, enzymolyzing it, inactivating the enzyme, centrifuging, washing, drying, grinding, and sieving. Based on different heat treatments, the invention selects reagents and enzyme preparations to remove related components from cassava flour, and uses a combined treatment method to make the digestibility of the prepared cassava flour present different digestion change trends, the cassava flour treated with steaming and frying significantly increases the content of resistant starch, and the cassava flour treated with boiling significantly increases the content of fast-digestible starch, showing different performances and qualities, and even better than the existing level in some aspects. Compared with physical processes and chemical means, the invention significantly changes the content of resistant starch in cassava after heat treatment on the basis of cost saving, is simple to operate, has low cost, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 It is a schematic diagram of the confocal laser scanning comparison of cassava flour of Comparative Example 2, defatted cassava flour of Example 1 and defatted-non-starch polysaccharide-removed cassava flour of Example 2; wherein, A1-D1: represent cassava flour, cassava flour obtained after boiling treatment, cassava flour obtained after steaming treatment, and cassava flour obtained after frying treatment, respectively; A2-D2: represent defatted cassava flour, defatted cassava flour after boiling treatment, defatted cassava flour after steaming treatment, and defatted cassava flour after frying treatment, respectively; A3-D3: represent cassava flour from which lipids and non-starch polysaccharides are removed, cassava flour from which lipids and non-starch polysaccharides are removed after boiling treatment, cassava flour from which lipids and non-starch polysaccharides are removed after steaming treatment, and cassava flour from which lipids and non-starch polysaccharides are removed after frying treatment, respectively. DETAILED DESCRIPTION

[0079] The present invention provides a combined treatment method for improving cassava digestibility and its application. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It should be particularly pointed out that all similar replacements and modifications are obvious to those skilled in the art, and they all belong to the scope of protection of the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0080] It should be understood that the expression "one or more of..." includes each of the items recited after the expression individually and in various different combinations of two or more of the recited items, unless otherwise understood from the context and usage. The expression "and / or" in combination with three or more recited items should be understood to have the same meaning, unless otherwise understood from the context.

[0081] The use of the terms "comprising", "having" or "containing", including their grammatical synonyms, should generally be understood as open and non-restrictive, for example not excluding other unrecited elements or steps, unless otherwise specifically stated or otherwise understood from the context.

[0082] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0083] In this application, "at least one" means one or more, "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0084] It should be understood that the order of steps or the order in which certain actions are performed is not important as long as the present invention remains operable. In addition, two or more steps or actions may be performed simultaneously.

[0085] The use of any and all examples or exemplary language, such as "for example" or "including", herein is intended only to better illustrate the invention and does not limit the scope of the invention unless otherwise claimed. No language in this specification should be construed as indicating that any non-claimed element is essential to the practice of the invention.

[0086] In addition, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise expressly stated, it should be understood that all ranges, quantities, values ​​and percentages used in this disclosure are modified by "about". Here, "about" generally means that the actual value is within plus or minus 10%, 5%, 1% or 0.5% of a specific value or range.

[0087] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0088] Some cases are recorded in the embodiments and comparative examples of the present invention, wherein the embodiments show certain implementation modes of the present invention. However, this does not mean that the effects of the present invention can only be achieved in these cases.

[0089] In order to further illustrate the present invention, a combined treatment method for improving cassava digestibility and its application provided by the present invention are described in detail below in conjunction with examples.

[0090] Comparative Example 1: Boiling, steaming and frying cassava starch

[0091] The cassava roots were peeled, washed, cut into small pieces with a slicer, suspended in water, homogenized in a stone mill for 2 minutes, and filtered with a 74μm pore size mesh. The filtrate was precipitated until a dense and firm starch layer was formed. The supernatant was poured out, the starch layer was washed three times again, and placed at 45℃ for 48h. The dried cassava starch was ground by a multifunctional grinder through a 150μm pore size mesh sieve, sealed in a plastic bag, and stored at 4℃ in the dark.

[0092] Add cassava starch (25 g) to 30 mL of distilled water to prepare starch milk with a moisture content of 55% and place it in a beaker. Add 250 mL of water to another beaker and boil it. Add the starch milk and boil it for 25 minutes, then cool it to room temperature.

[0093] Add cassava starch (25 g) to 30 mL of distilled water to prepare a starch milk with a moisture content of 55% and place it in a beaker. Boil 1500 mL of water in a steamer, place it in a steamer, steam for 25 minutes, and cool to room temperature.

[0094] Add cassava starch (25 g) to 30 mL of distilled water to prepare a starch milk with a moisture content of 55% and place it in a beaker. Add 200 mL of oil to another beaker, place it in a fryer and heat it to 180° C. Add the starch milk and fry it for 25 minutes. Then discard the hot oil immediately and cool it to room temperature.

[0095] The sample of the cassava starch treated as above is placed at 45° C. for 48 hours until the moisture content is ≤10%. The dried cassava starch is ground by a multifunctional grinder through a 150 μm mesh sieve, sealed in a plastic bag, and stored at 4° C. in the dark. The dried and crushed fried cassava starch is defatted by mixing with 200 mL of petroleum ether and placing for 4 hours. The defatted sample is placed at room temperature for 1 hour, sealed in a plastic bag, and stored at room temperature in the dark.

[0096] The heat-treated cassava starch prepared by the present invention was used to measure the resistant starch content and glycemic index in the cassava starch. The results show that the resistant starch content of the cassava starch under different heat treatments is different, wherein the resistant starch content of the cassava starch treated with water is 12.21±0.83%, the resistant starch of the cassava starch treated with steam is 11.97±0.31%, and the resistant starch of the cassava starch treated with frying is 20.57±0.30%, while the glycemic index of the cassava starch under water boiling and steaming treatments is 91.60±0.56 and 94.33±0.71, and the glycemic index of the cassava starch treated with frying is 76.07±0.75.

[0097] Comparative Example 2: Preparation of cassava flour by boiling, steaming and frying cassava

[0098] Preparation of cassava flour by boiling, steaming and frying cassava: Select fresh cassava with a middle diameter of 5±0.5cm, remove the outer skin and inner skin, cut off the head and tail, take the middle section, wash and cut into a cylinder with a thickness of 2cm. Weigh 250g of cassava for boiling, steaming and frying for 25min, add 2500mL and 1000mL of distilled water for boiling and steaming respectively. Add 2L of edible oil for frying at 180℃, and put oil-absorbing paper to cool to room temperature after frying.

[0099] Hot air drying: The heat-treated samples were dried in an electric constant temperature air drying oven (45°C, 48h) until the moisture content was ≤10%. The dried cassava was ground by a multifunctional grinder, passed through a 150 μm mesh sieve, sealed in a plastic bag, and stored at room temperature away from light.

[0100] The heat-treated cassava flour prepared by the present invention is used to measure the resistant starch content and the glycemic index in the cassava flour. The results show that the resistant starch content is different under different heat treatments, wherein the resistant starch content of the cassava flour treated with water is 21.07±1.21%, the resistant starch of the cassava flour treated with steam is 18.62±2.08%, and the resistant starch of the cassava flour treated with frying is 11.74±1.13%. The glycemic index of the cassava flour after the heat treatment is significantly increased, wherein the blood sugar content of the cassava flour treated with frying is 95.33±0.25, the blood sugar index of the cassava flour treated with steaming is 81.20±0.40, and the blood sugar index of the cassava flour treated with water boiling is 74.77±0.83.

[0101] Example 1: Preparation of defatted heat-treated cassava flour

[0102] Preparation of defatted heat-treated cassava flour: 25 g of the heat-treated cassava flour prepared in Comparative Example 2 was weighed and mixed with 200 mL of petroleum ether, stirred continuously at room temperature for 4 h, and then centrifuged at 4000 r / min and 4° C. for 10 min, and repeated three times.

[0103] The heat-treated cassava flour prepared by the present invention is used to measure the resistant starch content and glycemic index in the cassava flour. The results show that the content of the heat-treated resistant starch after defatting is improved compared with that of Comparative Example 2. The content of the resistant starch of the boiled cassava is 23.71±0.57%, the content of the steamed cassava is 19.57±0.41%, and the content of the fried cassava is 18.20±1.68%. After defatting, the glycemic index of the heat treatment is reduced, but the order of magnitude is not changed. The glycemic index of the fried cassava flour is 82.63±0.35, the glycemic index of the steamed cassava flour is 79.50±0.30, and the glycemic index of the boiled cassava flour is 71.40±0.46.

[0104] Example 2: Preparation of defatted and non-starch polysaccharide-free heat-treated cassava flour

[0105] Preparation of defatted-non-starch polysaccharide-removed heat-treated cassava flour: Based on the defatting method of Example 2, 4.0 g of defatted cassava flour was suspended in 40 mL of sodium acetate buffer (0.1 M, pH = 5.2), 20 U of cellulase, 20 U of hemicellulase and 20 U of pectinase were added, and the mixture was placed in a 200 mL centrifuge bottle. The reaction mixture was incubated in a water bath shaker at 37° C. for 40 min, 160 mL of ethanol was added to inactivate the reaction, and the slurry was centrifuged at 10,000 r / min at 4° C. for 30 min, and then washed twice with 80% ethanol.

[0106] Hot air drying: The heat-treated samples were dried in an electric constant temperature air drying oven (45°C, 48h) until the moisture content was ≤10%. The dried cassava was ground by a multifunctional grinder, passed through a 150 μm mesh sieve, sealed in a plastic bag, and stored at room temperature away from light.

[0107] The resistant starch content and glycemic index of the cassava flour prepared by the present invention were measured. The results show that the heat-treated resistant starch content after defatted-free non-starch polysaccharide treatment changed differently. The resistant starch content of the cassava treated with water was 21.04±0.13%, the resistant starch of the steamed treatment was 32.53±0.66%, and the resistant starch of the fried treatment was 27.02±2.52%, among which the resistant starch content of the steamed treatment was the highest. Compared with the glycemic content of Comparative Example 2, the glycemic index content of the water-boiled treatment was 75.23±0.60, which increased by 0.46%, while the glycemic index contents of the steamed treatment and the fried treatment were 62.13±0.50 and 67.83±0.31, which decreased by 23.49% and 28.85%, respectively, indicating that this method is beneficial to reducing the postprandial glycemic index in the steamed and fried heat treatments, among which the fried treatment reduced the most, while the water-boiled treatment increased the glycemic index.

[0108] Table 1 is a comparison of the digestibility and glycemic index of cassava starch in Comparative Example 1, cassava flour in Comparative Example 2, defatted cassava flour in Example 1, and defatted-non-starch polysaccharide-free cassava flour in Example 2

[0109]

[0110] Note: Different letters in the same column indicate significant differences (P<0.05); RDS: rapidly digestible starch; SDS: slowly digestible starch; RS: resistant starch; GI: glycemic index; CS: cassava starch; BS: boiled cassava starch; SS: steamed cassava starch; FS: fried cassava starch; CF: cassava flour; BC: boiled cassava flour; SC: steamed cassava flour; FC: fried cassava flour; DF-CF: defatted cassava flour; DF-BC: defatted cassava flour after boiling; DF-SC: defatted cassava flour after steaming; DF-FC: defatted cassava flour after frying; DF-RP-CF: cassava flour from which lipids and non-starch polysaccharides were removed; DF-RP-BC: cassava flour from which lipids and non-starch polysaccharides were removed after boiling; DF-RP-SC: cassava flour from which lipids and non-starch polysaccharides were removed after steaming; DF-RP-FC: cassava flour from which lipids and non-starch polysaccharides were removed after frying.

[0111] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A combined treatment method for improving cassava digestibility, characterized in that: include: A) pre-treating the cassava sample, heat-treating, drying, grinding, and sieving to obtain cassava flour; the heat treatment includes boiling, steaming, and frying; B) using petroleum ether to mix and defat cassava flour to obtain defatted cassava flour; C) Mixing defatted cassava flour and buffer, enzymolyzing, inactivating the enzyme, centrifuging, washing and drying to obtain the product.

2. The combined processing method according to claim 1, characterized in that: The cassava pretreatment comprises: selecting fresh cassava with a middle diameter of 3 to 6 cm, removing the outer skin and the inner skin, cutting off the head and the tail, taking the middle section, washing and cutting into a cylinder with a thickness of 1 to 5 cm.

3. The combined processing method according to claim 1, characterized in that: Step A) The boiling treatment comprises: the ratio of the mass of the cassava sample to the volume of distilled water is 1: (10-16) g: 2500-4000 mL; and the boiling time is 20-35 min.

4. The combined processing method according to claim 1, characterized in that: Step A) The steaming comprises: the ratio of the mass of the cassava sample to the volume of distilled water is 1: (4-8) g: 1000-2000 mL; and the steaming time is 20-35 min.

5. The combined processing method according to claim 1, characterized in that: Step A) The frying comprises: the ratio of the mass of the cassava sample to the volume of the edible oil is 1: (8-12) g: 2-3 L; the frying temperature is 150-180° C.; and the frying time is 20-35 min.

6. The combined processing method according to claim 1, characterized in that: The drying, grinding and sieving include: placing at 40-50° C. for 24-48 hours; crushing for 1-2 minutes; and sieving through a 100-150 μm pore size mesh sieve.

7. The combined processing method according to claim 1, characterized in that: Step B) comprises Cassava flour and petroleum ether were mixed and stirred, and centrifuged, and the process was repeated three times; The mass volume ratio of the cassava flour and petroleum ether is 1: (8-16) g: 200-400 mL; the stirring time is 1-4 hours; and the centrifugal parameters include: a rotation speed of 4000-6000 r / min and centrifugation at 4° C. for 10-15 minutes.

8. The combined processing method according to claim 1, characterized in that: Step C) the buffer is sodium acetate buffer; the concentration of the buffer is 0.1 M, pH = 5.2; The defatted cassava flour and buffer solution are mixed in a mass ratio of 1:(10-15) g:40-60 mL.

9. The combined processing method according to claim 1, characterized in that: Step C) the enzymes include cellulase, hemicellulase and pectinase; The enzymatic activity of the cellulase is 50U / mg, and the added amount is 20-30U; the enzymatic activity of the hemicellulase is 6U / mg, and the added amount is 20-30U; the enzymatic activity of the pectinase is 30U / mg, and the added amount is 20-30U.

10. The combined processing method according to claim 1, characterized in that: Step C) enzymatic hydrolysis parameters include: incubating at 37°C in a water bath shaker for 40 to 60 minutes; the enzyme inactivation includes: inactivating with ethanol; centrifugation includes: centrifugation at 10,000 r / min at 4°C for 30 to 50 minutes; washing includes: washing with 80% ethanol 2 to 3 times; drying includes: placing at 40 to 50°C for 24 to 48 hours; grinding: crushing for 1 to 2 minutes; sieving: sieving through a 100 to 150 μm pore size mesh sieve.

11. A cassava having improved digestibility, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 10.

12. Use of the preparation method according to any one of claims 1, 3 to 10 in reducing the digestibility of cassava flour.

13. Use of the preparation method according to any one of claims 1 to 2 and 5 to 10 in improving the digestibility of cassava flour.

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