Pea starch-tea polyphenol compound, cereal brewing powder containing pea starch-tea polyphenol compound and application of cereal brewing powder in preparation of health-care food or food with low glycemic index (GI) helpful for resisting oxidation

Abstract

The invention provides a pea starch-tea polyphenol compound, which is prepared by taking pea starch and tea polyphenol as raw materials, carrying out microwave radiation treatment through a microwave reactor with a cooling water circulation system, washing with a 50% ethanol solution, centrifuging, taking a centrifuged precipitate mixture, and freeze-drying, the weight ratio of the pea starch to the tea polyphenol is as follows: 8-12 parts of the pea starch and 1 part of the tea polyphenol. The invention also provides coarse cereal brewing powder which contains the pea starch-tea polyphenol compound. The invention further provides new application of the pea starch-tea polyphenol compound and the coarse cereal brewing powder. The pea starch-tea polyphenol compound prepared by microwaves is high in slowly digestible starch content and resistant starch content, low in quickly digestible starch content and low in starch in-vitro hydrolysis rate. The raw materials of the brewing powder are simple and purely natural, the taste is rich and fine, the antioxidant activity is high, and the organism immunity is improved.

Description

Technical Field

[0001] The invention relates to a pea starch-tea polyphenols complex, a coarse grain instant powder containing the complex, and use of the complex in preparing an antioxidant health food or a low glycemic index (GI) food. Background Art

[0002] Diabetes is a metabolic disease characterized by high blood sugar. In addition to taking medication and exercising appropriately, diabetics also need to strictly control their diet, which often causes patients to gradually lose weight or even become exhausted due to insufficient calories. In addition, the number of diabetics in the world is increasing year by year, so there is a wide demand for food suitable for diabetics in society.

[0003] GI foods, or glycemic index (GI) foods, refer to foods that are classified according to how quickly and how high the carbohydrates in the food affect blood sugar levels. GI is an indicator that measures the blood sugar response caused by food after a meal, and the glycemic index of glucose is usually set at 100 as a reference standard. If the GI value is greater than 70, this type of food can be quickly digested after entering the gastrointestinal tract, and the peak value of glucose after entering the blood is high, and blood sugar rises rapidly. GI values ​​between 55 and 70 are medium GI foods; GI values ​​below 55, this type of food stays in the gastrointestinal tract for a long time, the peak value of glucose after entering the blood is low, and the rate of blood sugar rises slowly, which is a low GI food. Low GI foods are very friendly to people with abnormal carbohydrate metabolism, such as diabetics, because they have the characteristics of slow digestion and slow blood sugar rise, which is beneficial to blood sugar control, maintaining blood sugar stability, and reducing the need for insulin. They are also beneficial to weight control and vascular health. Low GI foods cover a wide range of foods, including processed grains, milk and dairy products, beverages, convenience foods, pastry foods, frozen foods, candy foods, alcoholic foods, fruits and their products, beans and their products, vegetables and their products, bee products, and other foods containing available carbohydrates. However, whether it is a low GI food ultimately needs to be determined by human blood sugar test data. When the measured GI value is ≤55, the food being tested can be determined as a low GI food.

[0004] Starch is a key plant carbohydrate that is commonly used by humans as an energy source. Many studies have confirmed the close link between starch intake and an increased likelihood of diabetes, heart disease, obesity, and cancer. Starch can be divided into three categories based on digestion: rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). RDS is quickly broken down and efficiently absorbed in the small intestine, while SDS is metabolized more slowly. Resistant starch is not broken down in the upper digestive system but is used by bacteria in the colon, which is essential for maintaining colon health. Consumption of RDS can lead to significant fluctuations in blood sugar levels after meals, posing a potential health hazard. Therefore, low-glycemic index starch foods are important for diabetic patients and have received widespread attention in recent years.

[0005] Pea is a globally important food crop, with China being a key contributor to its global production and occupying a pivotal position in the agricultural sector. The main component of pea seeds, called pea starch (PS), accounts for a considerable proportion of the dry seed mass, ranging from 24.7% to 51.2%. Pea starch is notable for its high amylose content, and the resistant starch content ranges from 7.9% to 22.2%. This unique composition gives PS a high potential to be used as a dietary fiber to create functional foods with a low glycemic index. Pea starch has emerged as a promising starch raw material. This has the potential to bring significant health benefits to humans.

[0006] Tea polyphenols (TPs), which are rich in catechins and extracted from tea, have natural antioxidant properties and are safe to use in food, showing significant antioxidant effects. Numerous studies have shown that TPs significantly affect the physicochemical properties of starch from different plant sources as well as in vitro digestibility. Studies have shown that TPs can effectively reduce starch retrogradation and digestion efficiency by using sophisticated methods such as differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Modulating the interaction between tea polyphenols and starch can help achieve specific functional properties in food systems.

[0007] Application No. 201710347311.9, Invention Name: A method for preparing a lotus seed starch-tea polyphenols complex, provides a method for preparing a lotus seed starch-tea polyphenols complex, comprising dissolving tea polyphenols in water, adjusting the solution to alkalinity, introducing oxygen into the solution for oxidation reaction to generate quinone compounds; mixing an amylase solution with a quinone compound and subjecting it to ultrahigh pressure treatment, centrifuging and removing the supernatant to obtain a cross-linked polymer; mixing lotus seed starch with a phosphate buffer solution having a pH value of 4.7 and heating it, adding a cross-linked polymer, subjecting it to microwave-ultrasonic intermittent treatment, then subjecting it to enzyme inactivation treatment, then washing it until the system is neutral, filtering it to obtain a quinone compound-lotus seed starch complex; dissolving the quinone compound-lotus seed starch complex in a solvent, adding a hydrogenation catalyst and charging it with hydrogen for reaction, then filtering it to obtain a filtrate, and drying the filtrate to obtain a lotus seed starch-tea polyphenols complex. The prepared lotus seed starch-tea polyphenols complex has a high composite index and can effectively reduce the degradation and deterioration of tea polyphenols during the preparation process.

[0008] Application number 201710844398.0, invention name: A method for preparing starch-tea polyphenols complex by grinding technology, relates to a method for preparing starch-tea polyphenols complex by grinding technology. Mainly using starch as the main body, using grinding method, grinding tea polyphenols and starch in a certain proportion at room temperature for a required time, using the ability of starch hydrophobic spiral cavity to generate complex, embedding tea polyphenols to form a complex, the prepared product can not only improve the bioavailability of tea polyphenols, change starch digestibility, but also extend the shelf life of the product.

[0009] Liu Hualing, Preparation and characterization of different amylose-tea polyphenols complexes, Agricultural Products Processing, July 2023. Type B microcrystalline starch and type V microcrystalline starch were prepared with potato starch, and different microcrystalline starches were mixed with tea polyphenols. Different amylose-tea polyphenols complex samples were prepared by condensation reflux method, pressure steam method and stirring method.

[0010] Liu Ziwei, et al., Study on the properties of mung bean starch and polyphenol complexes under heat treatment conditions, Heilongjiang Bayi Agricultural University, 2023.04, discloses the interaction mechanism of mung bean starch polyphenol complexes and the effect of food-derived polyphenols on the properties of mung bean starch. Experiments have shown that when mung bean starch polyphenol complexes are prepared at different heat treatment temperatures, the structure, physicochemical and digestibility of the mung bean starch polyphenol complexes will change to varying degrees compared with the original starch, indicating that mung bean food-derived polyphenols will interact with starch during the heat treatment process, thereby affecting the properties of the complex and making it have slow digestion functional characteristics.

[0011] Due to the complex structure of starch, it has a multi-scale structure. Starch has a coaxial semi-crystalline multi-scale structure, which increases from the nanometer level to the micrometer level, including complex structural elements such as lamellae and amorphous regions, small pieces, annual rings and granules; the chain length distribution of starch has a significant effect on its structural and functional properties. Starch is composed of chains of different lengths, and the length distribution of these chains plays a decisive role in the physicochemical properties and functional properties of starch. Starch from different sources has different ratios of amylose to amylopectin, which affects the gelatinization characteristics, solubility, swelling power, etc. of starch; the shape, size and morphology of starch particles vary depending on the plant source, which determines the physicochemical properties of starch; in addition, starch from different sources has differences in gelatinization temperature, peak viscosity, etc. These properties are very important for the application of starch in food processing. In addition, due to different sources, the swelling power, solubility, rheological properties, X-ray diffraction properties, nutritional properties, physicochemical properties, etc. are also different.

[0012] There is no report on preparing a complex of pea starch and tea polyphenols, nor is there any report on related products containing the pea starch-tea polyphenols complex. Summary of the invention

[0013] The technical scheme of the present invention provides a pea starch-tea polyphenols complex, a grain mixing powder containing the complex, and use of the complex in preparing an antioxidant health food or a low glycemic index (GI) food.

[0014] The invention provides a pea starch-tea polyphenols complex. The pea starch and tea polyphenols are used as raw materials, and are subjected to microwave radiation treatment in a microwave reactor with a cooling water circulation system, and then washed and centrifuged with a 50% ethanol solution. The precipitated mixture after centrifugation is taken and freeze-dried to obtain the complex. The weight ratio of the pea starch and tea polyphenols is: 8-12 parts of pea starch and 1 part of tea polyphenols.

[0015] Further preferably, the weight ratio of pea starch to tea polyphenols is: 10 parts of pea starch to 1 part of tea polyphenols.

[0016] The microwave power is 150-350 W, and the microwave treatment time is 8 min.

[0017] Preferably, the microwave power is 300W.

[0018] The present invention provides a method for preparing a pea starch-tea polyphenols complex, which comprises the following steps:

[0019] a. Weigh the raw materials pea starch and tea polyphenols in different weight ratios and mix and dissolve them in distilled water;

[0020] b. Transfer the mixture to a microwave reactor with a cooling water circulation system, set the microwave power to 150-350W and irradiate the mixture with microwaves for 8 minutes;

[0021] c. Cool the mixture after microwave treatment to room temperature, then wash it with 50% ethanol solution, centrifuge it at 4000×g for 10 min, discard the supernatant and remove free tea polyphenols;

[0022] d. freeze-drying the washed and centrifuged precipitate mixture for 48 hours; the condenser temperature maintained during the freeze-drying process was about -80°C;

[0023] e. Grind and powder the freeze-dried sample, and sieve it with a 120-mesh sieve to obtain the pea starch-tea polyphenols complex.

[0024] The invention provides a miscellaneous grain instant powder, which contains the pea starch-tea polyphenols complex.

[0025] Further preferably, it is composed of the following raw materials in weight ratio:

[0026] Pea starch-tea polyphenols complex: 8-12 parts, quinoa powder: 12-18 parts, chickpea powder 20-30 parts, oat powder 8-12 parts, chia seed powder 12-18 parts, black sesame powder 12-18 parts, inulin 8-12 parts.

[0027] More preferably, it is composed of the following raw materials in weight ratio:

[0028] Pea starch-tea polyphenols complex: 10 parts, quinoa powder: 15 parts, chickpea powder 25 parts, oat powder 10 parts, chia seed powder 15 parts, black sesame powder 15 parts, inulin 10 parts.

[0029] The multi-grain instant powder of the present invention further contains a thickener, an emulsifier, and a flavor corrector, wherein the amount of the thickener is 0.1%-0.30% w / w of the total amount of the raw materials, the amount of the emulsifier is 0.10%-0.50% w / w of the total amount of the raw materials, and the amount of the flavor corrector is 4%-12% w / w of the total amount of the raw materials;

[0030] Preferably, the thickener is konjac gum, and the amount used is 0.2% of the total amount of raw materials; the emulsifier is glyceryl monostearate, and the amount used is 0.3% of the total amount of raw materials; the flavoring agent is xylitol, and the amount used is 10% of the total amount of raw materials.

[0031] The present invention also provides the use of the pea starch-tea polyphenols complex and the coarse grain instant powder according to any one of claims 6 to 9 in preparing health foods that are helpful for anti-oxidation or foods with low glycemic index (GI).

[0032] The microwave irradiation technology used in the present invention belongs to the category of non-ionizing radiation energy and has great potential in effectively changing the structural and functional properties of food materials. Microwaves are known for their efficiency and convenience compared to traditional heating methods. They allow direct interaction with polar molecules in starch, changing the granular structure through rapid heating and "polar molecular vibration mechanism". During digestion, microwave-treated starch undergoes more significant molecular rearrangements than starch treated by traditional methods. In addition, microwave power helps to break down hydrogen bonds in starch molecules and affects the interaction between starch and polyphenols. Polyphenols are widely used in food processing to mitigate the risks associated with various non-communicable chronic diseases. Their unique molecular structure enables them to form complexes with starch rather than existing as independent ingredients.

[0033] The pea starch-tea polyphenols complex prepared by microwave of the present invention has high content of slowly digestible starch and resistant starch, low content of quickly digestible starch, and slow in vitro hydrolysis rate of starch. The raw materials of the instant powder of the present invention are simple and natural, and the taste is rich and delicate. The multi-grain instant powder of this formula is rich in nutrients and has a low eGI, which can meet the functional and taste requirements of diabetics and most people, has high antioxidant activity, and improves the body's immunity. The present invention provides a reliable platform for the development of low-glycemic index foods, provides an environmentally sustainable method for food processing, promotes human welfare, and promotes innovation in the food industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Results of tea polyphenol content determination (letters (af) in the figure indicate that the tea polyphenol content was significantly different between physical mixing and different microwave powers (p<0.05));

[0035] Figure 2 Scanning electron microscopy (SEM) results;

[0036] Figure 3 The results of the in vitro digestion characteristics of the composite starch (the letters (ae) in the figure indicate that the same index is significantly different between different microwave powers (p<0.05));

[0037] Figure 4 (Left-right) are the sensory evaluation scores of konjac gum addition, glyceryl monostearate addition and xylitol addition (the letters (ae) in the figure indicate significant differences between different addition amounts (p<0.05));

[0038] Figure 5 GI test results. DETAILED DESCRIPTION

[0039] Example 1 Preparation method of pea starch-tea polyphenols complex of the present invention

[0040] 1) Mix 10.0 g of pea starch and 1.0 g of tea polyphenols and dissolve them in 150 mL of distilled water.

[0041] 2) Afterwards, the mixture was transferred into a microwave reactor with a cooling water circulation system (MKX-H1C1A, Qingdao Maikewei Microwave Innovation Technology Co., Ltd., China). The microwave powers were set to 150, 200, 250, 300, and 350 W for 8 min.

[0042] 3) The mixture after microwave treatment was cooled to room temperature, then washed with 50% ethanol solution, centrifuged at 4000×g for 10 min, and the supernatant was discarded to remove free tea polyphenols. (Repeat three times)

[0043] 4) Subsequently, the washed and centrifuged precipitation mixture was freeze-dried for 48 hours. The condenser temperature maintained during the freeze-drying process was about -80°C.

[0044] 5) Finally, the freeze-dried sample was ground and powdered, and sieved with a 120-mesh sieve to obtain a pea starch-tea polyphenols complex (hereinafter referred to as PS-TPs complex).

[0045] Example 2 Determination of the composite physical and chemical properties, structural characterization and digestive characteristics of pea starch-tea polyphenols of the present invention

[0046] 1. Control group: Method and steps for physically mixing the pea starch-tea polyphenols mixture:

[0047] The preparation of the physical mixture was similar to that of the microwave-treated sample, except that 10.0 g of pea starch and 1.0 g of tea polyphenols were mixed evenly and ground manually in a mortar for 8 min.

[0048] 2. Determination method of compound degree (content of tea polyphenols):

[0049] 1) Suspend 10 mg of the sample in 1 mL of ultrapure water and heat in a constant temperature water bath at 90 °C for 10 min.

[0050] 2) After heating, the samples were centrifuged at 4000×g for 10 min and then cooled.

[0051] 3) Then, 0.1 mL of the supernatant was mixed with 0.5 mL of diluted Folin phenol reagent (one tenth of the original concentration) and reacted at 30° C. for 5 min.

[0052] 4) Then, add 0.5 mL of 20% (w / v) Na 2 CO 3 The solution was mixed well.

[0053] 5) The samples were protected from light and reacted for 30 min, and then the absorbance was measured at 725 nm using SYNERGYH1 multifunctional enzyme marker (BioTek Instruments, Vermont, USA).

[0054] 6) Generate a standard curve using gallic acid (GA) with a concentration range of 0 to 0.12 mg / mL. 2 = 0.9985 and n = 7. The results are expressed as milligrams of tea polyphenols equivalent per gram of dry weight pea starch (mg GAE / g PS).

[0055] 7) Measurement results ( Figure 1 ):

[0056] The content of TPs in the physical mixture (PM) was low. This observation indicated that the physical mixture had a weak complexation effect on PS and TPs. Therefore, this study believed that the physical mixture was mainly composed of pea starch.

[0057] The results showed that the use of microwaves significantly improved the binding between starch and polyphenols. In addition, the use of microwaves and increasing their power (150-300 W) resulted in a significant increase in the concentration of attached TPs in the PS-TPs complex, far exceeding the amount obtained by physical mixing techniques. However, when the microwave power was increased to 350 W, the TPs content in the complex decreased. These results indicate that the optimal microwave power to achieve the highest degree of complexation between PS and TPs is 300 W.

[0058] 3. Observation and determination method of the apparent structure of the composite using scanning electron microscopy (SEM):

[0059] 1) The sample structure was observed using a scanning electron microscope (SEM, JLB-4700F, JEOL, Tokyo, Japan). An appropriate amount of dried sample was firmly fixed on the SEM device with double-sided tape (to remove floating powder) and sprayed with gold. The whole process was carried out in a controllable low vacuum environment.

[0060] 2) Then set the acceleration voltage to 15keV to optimize the image quality.

[0061] 3) Take photos and observe at magnifications of 2000×, 5000× and 10000×.

[0062] 4) Measurement results ( Figure 2 ):

[0063] Scanning electron microscopy was used to observe the effects of different molecular weights and physical mixtures (PM) on the microstructure of PS-TPs complexes. Figure 2As shown in the figure, the morphology of PM and PS-TPs complexes is obviously different. The starch of PM is round and oval particles with smooth surface. After MW treatment, the starch granules are obviously non-uniform in appearance, with a change in shape and increased surface porosity. These results indicate that microwave treatment has the ability to destroy the surface integrity of PS. The degree of damage to starch granules increases with the increase of microwave power. This phenomenon may be due to the deep penetration of TPs into starch granules under exposure to microwave radiation. This enables them to attach to starch chains, decompose the crystalline regions of starch, and accelerate the decomposition of the original starch structure. In addition, multiple aggregates adhere to MW-treated PS particles, resulting in an irregular distribution of particle sizes. These aggregates may be v-helical complexes formed by TPs attached to leached amylose through hydrogen bonding, hydrophobic interactions or other types of forces. However, the generation of these complexes may hinder the structural connection between starch chains and damage the surface integrity of starch gels, leading to the development of fragments and irregular cavities. Therefore, microwave treatment promotes the formation of complexes between PS and TPs, while TPs accelerate the destruction of the initial structure of starch.

[0064] 4. Determination of in vitro digestibility of complex starch:

[0065] 1) Freshly prepared porcine pancreatic α-amylase (PPA) and amyloglucosidase (AMG) solutions were used for digestion assays to ensure accurate results.

[0066] 2) Take 100 mg of the sample and add it to sodium acetate buffer (0.1 mol / L, pH 5.2, 15.0 mL), mix well, and place in a boiling water bath for 30 minutes.

[0067] Subsequently, 10 mL of PPA solution (280 U / mL) and 1 mL of AMG solution (2500 U / mL) were added to initiate the digestion process.

[0068] 3) Afterwards, the mixture was transferred to a 37°C water bath for 180 min while gently stirring at 120 rpm to ensure uniform digestion.

[0069] 4) Take 0.5 mL of sample regularly and mix it with 4.5 mL of 80% ethanol solution to stop the enzyme activity and separate the undigested starch.

[0070] The glucose content in the mixture was accurately determined using the 3,5-dinitrosalicylic acid (DNS) technique. Each sample was analyzed in triplicate to ensure reproducibility and statistical reliability.

[0071] 5) Rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) represent the amount of starch hydrolyzed into glucose at different rates: RDS within 20 minutes, SDS between 20 and 120 minutes, and RS without decomposition after 120 minutes. RDS, SDS and RS contents were measured using formulas (4), (5) and (6):

[0072] RDS(%)=(G 20 -FG)×0.9 / TS×100% (4)

[0073] SDS(%)=(G 120 -G 20 )×0.9 / TS×100% (5)

[0074] RS(%)=(TS-RDS-SDS) / TS×100% (6)

[0075] The amount of glucose released after 20 min was recorded as G 20 (mg), G 120 represents the amount of glucose released after 120 min in mg. FG represents the free glucose present in mg, and TS represents the total starch content of the complex used for digestibility determination (mg). In this case, the TS value is equivalent to 100 mg.

[0076] 6) Determination results (see Figure 3 ):

[0077] Figure 3 (a) Shows the effect of PM and MW treatment on the in vitro digestibility of PS-TPs complexes, especially the ratio of rapidly digestible starch, slowly digestible starch and resistant starch. Compared with the physical mixture, microwave treatment significantly increased the levels of SDS and RS and significantly reduced the amount of RDS in PS-TPs complexes when TPs were present. It has been demonstrated that the introduction of TPs significantly increases the resistance of carbohydrates to enzymatic hydrolysis. The effect was particularly significant when the microwave power reached 300 W.

[0078] The hydrolysis rate of starch Figure 3 (b) The digestion and hydrolysis rates of microwave-treated PS-TPs complexes were significantly lower than those of PM, indicating that the enzyme activity on these complexes was greatly reduced, inhibiting starch digestion.

[0079] Example 3 Preparation of instant powder of the present invention

[0080] 1. Formula design requirements:

[0081] (1) Target group of the product: The instant powder is positioned as an instant powder suitable for adults and middle-aged and elderly diabetics.

[0082] (2) Determine the reference intake range of dietary nutrients based on the dietary guidelines issued by the World Health Organization, including the Dietary Reference Intakes for Chinese Residents, the Dietary Guidelines for Adults with Diabetes, and the Dietary Guidelines for the Elderly, so that the nutrients in the formula are balanced and can meet the product positioning requirements.

[0083] 2. Linear programming is used to design the formula through Excel software. Under the condition of meeting various constraints, the proportion of each raw material under the goal of lowest price cost can be obtained, and a calculation result report can be obtained.

[0084] (1) Determine the decision variables: The decision variables refer to the proportion of each raw material in the instant powder formula. n Represents the proportion of each raw material (a 1 -Pea starch-tea polyphenols complex, a 2 - Quinoa flour, a 3 - Chickpea flour, a 4 - Oatmeal flour, a 5 -Chia seed powder, a 6 -Black sesame powder, a 7 -Inulin)

[0085] (2) Determine the objective function: On the basis that the nutritional ingredients of the formula meet the specified conditions, in order to maximize the company's profits and maximize consumer acceptability, this experiment sets the objective function as the minimum price cost Smin of the instant powder formula. The formula objective function is as follows: S min =0.8a 1 +4a 2 +a 3 +2.4a 4 +2a 5 +2.4a 6 +7a 7

[0086] Table 1 Initial linear programming model for instant powder

[0087]

[0088] 3. The constraint equation of linear programming is based on the human body's demand for energy and major nutrients:

[0089] Energy: 270≤342a 1 +357a 2 +340a 3 +338a 4 +486a 5 +559a 6 +196a 7 ≤540

[0090] Protein: 10≤0.6a 1 +14a 2 +21.2a 3 +10.1a 4 +16.5a 5 +19.1a 6 +0.0a 7 ≤40

[0091] Fat: 6≤0a 1 +6a 2 +4.2a 3 +0.2a 4 +30.7a 5 +46.1a 6 +0.0a 7 ≤15

[0092] Carbohydrates: 27 ≤ 85a 1 +57.8a 2 +60.1a 3 +77.4a 4 +42.1a 5 +24a 6 +5.20a 7 ≤60

[0093] Dietary fiber: 12 ≤ 0.3a 1 +6.5a 2 +11.6a 3 +6a 4 +34.4a 5 +14a 6 +91.80a 7 ≤25

[0094] 4. Get the basic formula:

[0095] Through LINGO linear programming, a basic formula was designed: pea starch-tea polyphenols complex: 10%, quinoa powder: 15%, chickpea powder 25%, oat powder 10%, chia seed powder 15%, black sesame powder 15%, inulin 10%, with a price of 2.74 yuan.

[0096] 5. Preparation method of instant powder

[0097] 5.1 Each raw material is matured and mixed separately:

[0098] Pea starch-tea polyphenols complex: microwave cooking, freeze drying

[0099] Quinoa flour: extruded

[0100] Chickpea flour: microwave low temperature cooking, original grain grinding

[0101] Oatmeal powder: low temperature baking, ultra-fine grinding

[0102] Chia seed powder: low temperature roasted, baked

[0103] Black sesame powder: low temperature baking, baked

[0104] Then, the raw materials were added in proportion and mixed and powdered to make the basic formula of the instant powder uniform. Then, konjac gum (0.1%-0.30%), glyceryl monostearate (0.10%-0.50%) and xylitol (4%-12%) were added as improvers to carry out single factor and orthogonal experiments to improve the quality of the instant powder.

[0105] 5.2 Single factor experimental analysis of improver:

[0106] 5.2.1 Konjac Gum Addition Amount

[0107] Based on the processed instant powder, 0.3% of glyceryl monostearate and 8% of xylitol were added, and 0.1%, 0.15%, 0.2%, 0.25% and 0.3% of konjac gum were added to the total amount of the basic formula respectively. The mixture was mixed evenly, and the water solubility index and centrifugal sedimentation rate were determined, and sensory evaluation and comprehensive score evaluation were carried out.

[0108] 5.2.2 Addition amount of glyceryl monostearate

[0109] Based on the processed instant powder, 0.2% konjac gum and 8% xylitol were added, and 0.1%, 0.2%, 0.3%, 0.4% and 0.5% konjac gum were added to the total amount of the basic formula respectively, and mixed evenly. The water solubility index and centrifugal sedimentation rate were determined, and sensory evaluation and comprehensive score evaluation were carried out.

[0110] 5.2.3 Xylitol Addition Amount

[0111] Based on the processed instant powder, 0.2% konjac gum and 0.3% glyceryl monostearate were added, and 4%, 6%, 8%, 10% and 12% of xylitol were added to the total amount of the basic formula respectively. The mixture was mixed evenly, and the water solubility index and centrifugal sedimentation rate were determined. Sensory evaluation and comprehensive score evaluation were also conducted.

[0112] 5.3 Orthogonal experiment of improver:

[0113] Based on the single factor test, in order to obtain the instant powder formula with the highest sensory total score, the orthogonal test method was used to select L9 (3 3 ) orthogonal table, taking the comprehensive score as the evaluation index, selected konjac gum, glyceryl monostearate and xylitol as three factors to be investigated, and conducted experiments at three levels to determine the optimal formula of the instant powder.

[0114] Table 2 Orthogonal test factor level design table

[0115]

[0116]

[0117] 5.4 Determination of water absorption index and water solubility index:

[0118] Weigh 2.0 g (m 0 ) into a constant weight centrifuge tube (m 1 ), add 20mL of distilled water, and use a vortex mixer to completely disperse the sample in the water. Keep in a 30℃ water bath for 30min, and shake vigorously every 10min. Centrifuge at 5500r / min for 15min. Separate the supernatant and the precipitate. After centrifugation, pour the supernatant into a weighing dish (m 2 ) and dried at 105℃ to constant weight. Record the weight of the weighing dish with the supernatant (m 3 ). At the same time, weigh the centrifuge tube and the precipitated gel weight (m4).

[0119]

[0120] Water absorption index scoring standard (60-100 points):

[0121] The water absorption index range is assumed to be 220-240%. Since the higher the water absorption, the better, we can set the lowest value of 220% as the benchmark score and set a range of score growth so that the full score is reached when the maximum value of 240% is reached.

[0122] Baseline score: Due to the large range (20% difference), we can set the baseline score to a lower score. Considering that we usually want the baseline score to reflect a certain level of performance, it is set to 60 points here.

[0123] Extra points for every 1% increase: In order to reach the full score at 240%, we need to calculate the extra points for every 1% increase. Since (100-60) / (240-220)=2, every 1% increase should add 2 points.

[0124] Calculation formula: Score = 60 + (water absorption index - 220) × 2

[0125] Full score condition: When the water absorption index reaches 240%, the score is 100 points.

[0126] Water solubility index scoring standard (40-100 points)

[0127] The water solubility index range is assumed to be 20-30%, and again, the higher the water solubility, the better.

[0128] Benchmark score: Set the lowest value of 20% as the benchmark score. Here we can directly set it to 40 points because the increase range of the water solubility index is relatively small (10%).

[0129] Extra points for every 1% increase: In order to reach full marks at 30%, we need to calculate the points that should be increased for every 1% increase. Since (100-40) / (30-20)=6, every 1% increase should add 6 points.

[0130] Calculation formula: score = 40 + (water solubility index - 20) × 6

[0131] Full score condition: When the water solubility index reaches 30%, the score is 100 points.

[0132] 5.5 Determination of centrifugal sedimentation rate:

[0133] Take an appropriate amount of powder and hot water (80℃) at a ratio of 1:5, weigh 15g of sample (m 1 ) in a centrifuge tube, centrifuge at 8000r / min for 20min, remove the supernatant, and weigh the remaining colloid mass (m 2 ).

[0134]

[0135] Centrifugal sedimentation rate scoring criteria (40-100 points):

[0136] The centrifugal sedimentation rate range is assumed to be 40-70%, but the lower the centrifugal sedimentation rate, the better.

[0137] Benchmark score: The highest value of 70% is set as the benchmark score, but considering that we hope to get a high score for a low centrifugation sedimentation rate, we can set the benchmark score to a lower score, such as 40 points (corresponding to 70%).

[0138] Extra points for every 1% decrease: In order to achieve full marks at 40%, we need to calculate the points that should be increased for every 1% decrease. Since (100-40) / (70-40)=2, 2 points should be added for every 1% decrease.

[0139] Calculation formula: score = 40 + (70-centrifugal sedimentation rate) × 2

[0140] Full score condition: When the centrifugal sedimentation rate reaches 40%, the score is 100 points.

[0141] 5.6 Sensory evaluation

[0142] Table 3 Sensory scoring standards for instant powder

[0143]

[0144]

[0145] 5.7 Calculation of comprehensive indicators:

[0146] The water absorption index, water solubility index, centrifugal sedimentation rate and sensory score were used as evaluation indicators, and the comprehensive score was used as the assessment indicator.

[0147] Comprehensive score = water absorption score * weight (0.2) + water solubility score * weight (0.2) + centrifugal sedimentation rate * weight (0.2) + sensory score * weight (0.4)

[0148] 6 Experimental results are shown in Table 4-5. Figure 4 :

[0149] Table 4 Results of various indicators of konjac gum addition

[0150]

[0151] Table 5 Results of various indicators of monostearate addition

[0152]

[0153] Table 6 Results of various indicators of xylitol addition

[0154]

[0155]

[0156] In the same row, the superscript letters (ae) after the data value indicate that the indicators differ significantly between different addition amounts (p<0.05).

[0157] According to the comprehensive scores, it can be obtained that in the instant powder of the present invention, the optimal addition amount of konjac gum is 0.2%, the optimal addition amount of monoglyceride is 0.3%, and the optimal addition amount of xylitol is 10%.

[0158] Table 7 Orthogonal test results analysis

[0159]

[0160] From the orthogonal experiment result table, it can be seen that the order of influence of the three factors on the comprehensive score is A>C>B, that is, the amount of konjac gum added>the amount of xylitol added>the amount of glyceryl monostearate added. The best factor combination is A2B3C2, that is, the most suitable formula affecting the comprehensive score of the instant powder is: konjac gum 0.20%, glyceryl monostearate 0.40%, xylitol 10.00%. It has been verified that the instant powder under this condition has a water absorption index score of 72.00 points, a water solubility index score of 64.00 points, a centrifugal sedimentation rate score of 93.20 points, a sensory evaluation score of 86.50 points, and a final comprehensive score of 80.44 points.

[0161] The beneficial effects of the present invention are demonstrated by the following efficacy tests.

[0162] Test Example 1 Determination of eGI and antioxidant activity of commercially available low GI instant powder and the optimal instant powder of the present invention

[0163] 1. Determination of the eGI value of the optimal instant powder formula:

[0164] Table 8 Preparation of simulated digestion stock solution

[0165]

[0166] 1. Preparation of electrolytes simulating artificial saliva, gastric juice and intestinal juice

[0167] Prepare the required electrolyte according to the following solution, and then add UP water to make the total volume 400mL. (The subsequent enzyme solution is prepared as needed)

[0168] Experimental steps:

[0169] (1) Oral digestion stage:

[0170] ① Preheat SSF electrolyte stock solution at 37℃.

[0171] Simulate oral digestion: weigh 0.5g of the powder and mix it with 4.5mL of hot water to make a powder solution, add 5mL of artificial saliva (50uL 0.3M CaCl 2， 150 mg porcine pancreatic α-amylase) was placed in a constant temperature water bath shaker at 37°C for 2 min (pH = 7).

[0172] (2) Stomach digestion stage:

[0173] ① Preparation of pepsin solution: Prepare porcine pepsin solution with a concentration of 40,000 U / mL using SGF solution in advance and allow it to fully dissolve.

[0174] ②Preheat porcine pepsin solution and SGF electrolyte stock solution at 37°C.

[0175] Simulated gastric digestion: The oral digested sample was mixed with 7.5 mL of preheated gastric stock solution, and 1.6 mL of peptic enzyme solution and 5 μL of 0.3 M CaCl were added. 2 , adjust the system pH to 3 with 6 mol / L hydrochloric acid solution, add water to the system volume to 20 mL, and place in a constant temperature water bath oscillator at 37°C for 2 h.

[0176] (3) Intestinal digestion stage:

[0177] ① Preparation of trypsin solution: Prepare porcine pepsin solution with a concentration of 4000U / mL using SIF intestinal fluid in advance and allow it to fully dissolve.

[0178] ② Preheat trypsin solution and SIF electrolyte solution at 37℃.

[0179] Simulated intestinal digestion: The gastric digested sample was mixed with 11 mL of intestinal stock solution, 5 mL of pancreatic enzyme solution, 2.5 mL of bile solution (160 mM) and 40 μL of 0.3 M CaCl 2 , adjust the pH to 7.0 with 1 mol / L NaOH solution, add water to a final volume of 40 mL, and incubate in a 37°C constant temperature water bath oscillator for 3 h.

[0180] At 20, 30, 60, 90, 120, 150, and 180 minutes, 1 mL of digestion solution was taken into a centrifuge tube, and the enzyme was inactivated in a boiling water bath for 10 minutes, followed by centrifugation at 5000 r / min for 10 minutes, and the supernatant was diluted 20 times for testing. The glucose content was determined by DNS method, and the corresponding starch hydrolysis rate was calculated.

[0181] The in vitro digestion hydrolysis curve was drawn with starch hydrolysis rate as the ordinate and hydrolysis time as the abscissa. The hydrolysis curve area (AUC and AUSC) of each sample and white bread in the range of 0-180 min was calculated using Origin software to obtain the sample hydrogenation index (HI). The sample glycemic index (eGI) was predicted and divided according to different GI values. GI < 55 was defined as low glycemic index food, 55 < GI < 70 was defined as medium glycemic index food, and 70 < GI was defined as high glycemic index food.

[0182] Calculation of starch hydrolysis rate (%), sample starch hydrolysis index (HI) and sample glycemic index (GI):

[0183] eGI=0.862HI+8.198

[0184] m is the amount of glucose released in the hydrolyzate, mg; HI is the hydrogenation index; AUC sample is the area under the sample digestion curve; AUC white bread is the area under the white bread digestion curve.

[0185] 2. Experimental results are shown in Figure 5 :

[0186] The results of this test showed that the commercially available low GI instant powder had a HI value of 44.46 and an eGI value of 46.53. The official GI value was 42, and the measured value was close to the official value. The instant powder of the present invention had a HI value of 36.34 and an eGI value of 39.53. Compared with the commercially available low GI instant powder, the instant powder of the pea starch-tea polyphenols complex in this study had a lower starch hydrolysis rate, which could delay digestion, and a GI value of 39.53 < 55, which was in line with the low GI food.

[0187] 2. Antioxidant activity determination: (take the digestive fluid of the prepared powder after 2 hours of simulated gastric and intestinal digestion in vitro for determination)

[0188] 1. ABTS + :

[0189] Take equal volumes of 7.0mmol / L ABTS solution and 2.45mmol / L potassium persulfate solution and mix them. Store in a dark place away from light for 12-16h. Dilute with pH 6.6 0.05mM PBS solution before use so that the absorbance of the working solution at 734nm is above 0.8.

[0190] Add 20 μL digestion solution + 200 μL ABTS working solution to the ELISA plate. Use an ELISA reader to shake for 6 minutes and measure the absorbance of the sample group at 734 nm.

[0191] The ABTS free radical scavenging rate was calculated according to the following formula:

[0192]

[0193] Where: A 0 is the absorbance of ABTS+UP water; A i is the absorbance of ABTS+ sample solution; A j is the absorbance of PBS + sample solution

[0194] 2. DPPH:

[0195] Prepare 0.35 mM DPPH working solution by first dissolving it in 15 mL of anhydrous ethanol, sonicating at low temperature for 30 min, vortexing for 5 min (observe for precipitation), and then adding UP water to prepare.

[0196] Take 5mL 0.35mM DPPH + 5mL UP water (after 1:1 mixing), add 50% ethanol solution and select appropriate preparation, such as 1:0.5, 1:1, 1:1.5, 1:2, and then measure the OD value to be around 0.9.

[0197] Determination method:

[0198] 25 μL digestion solution + 200 μL DPPH working solution, react at room temperature in the dark for 30 min, and measure the OD value at 517 nm.

[0199] The DPPH free radical scavenging rate was calculated according to the following formula:

[0200]

[0201] Where: A 0 is the absorbance of DPPH+UP water; A i is the absorbance of DPPH+ sample solution; Aj is the absorbance of UP water + sample solution

[0202] 3. Experimental results:

[0203] After 2 hours of gastric digestion, the optimal formula of instant powder had an in vitro antioxidant activity of ABTS free radical scavenging rate of 86.84% and an in vitro antioxidant activity of DPPH free radical scavenging rate of 58.29%; after 2 hours of intestinal digestion, the in vitro antioxidant activity of ABTS free radical scavenging rate was 75.59% and an in vitro antioxidant activity of DPPH free radical scavenging rate was 20.50%. The overall antioxidant activity was good.

Claims

1. A pea starch-tea polyphenols complex, characterized in that: The invention is prepared from pea starch and tea polyphenols as raw materials, which are subjected to microwave radiation treatment by a microwave reactor with a cooling water circulation system, washed with a 50% ethanol solution, centrifuged, and freeze-dried to obtain a precipitated mixture after centrifugation. The weight ratio of the pea starch and tea polyphenols is: 8-12 parts of pea starch and 1 part of tea polyphenols.

2. The pea starch-tea polyphenols composite according to claim 1, characterized in that: The weight ratio of the pea starch and tea polyphenols is: 10 parts of pea starch and 1 part of tea polyphenols.

3. The pea starch-tea polyphenols composite according to claim 1 or 2, characterized in that: The microwave power was 150-350 W, and the microwave treatment time was 8 min.

4. The pea starch-tea polyphenols composite according to claim 3, characterized in that: The microwave power is 300W.

5. A method for preparing a pea starch-tea polyphenols complex, characterized in that: It includes the following steps: a. Weigh the raw materials pea starch and tea polyphenols in different weight ratios and mix and dissolve them in distilled water; b. Transfer the mixture to a microwave reactor with a cooling water circulation system, set the microwave power to 150-350W, and irradiate the mixture with microwaves for 8 minutes; c. Cool the mixture after microwave treatment to room temperature, then wash it with 50% ethanol solution, centrifuge it at 4000×g for 10 min, discard the supernatant and remove free tea polyphenols; d. freeze-drying the washed and centrifuged precipitate mixture for 48 hours; the condenser temperature maintained during the freeze-drying process was about -80°C; e. Grind and powder the freeze-dried sample, and sieve it with a 120-mesh sieve to obtain the pea starch-tea polyphenols complex.

6. A miscellaneous grain instant powder, characterized in that: It contains the pea starch-tea polyphenols complex according to any one of claims 1 to 4.

7. The miscellaneous grains instant powder according to claim 6, characterized in that: It is composed of the following raw materials in weight ratio: Pea starch-tea polyphenols complex: 8-12 parts, quinoa powder: 12-18 parts, chickpea powder 20-30 parts, oat powder 8-12 parts, chia seed powder 12-18 parts, black sesame powder 12-18 parts, inulin 8-12 parts.

8. The miscellaneous grains instant powder according to claim 7, characterized in that: It is composed of the following raw materials in weight ratio: Pea starch-tea polyphenols complex: 10 parts, quinoa powder: 15 parts, chickpea powder 25 parts, oat powder 10 parts, chia seed powder 15 parts, black sesame powder 15 parts, inulin 10 parts.

9. The miscellaneous grains instant powder according to any one of claims 6 to 8, characterized in that: It also contains a thickener, an emulsifier, and a flavoring agent, wherein the amount of the thickener is 0.1%-0.30% w / w of the total amount of the raw materials, the amount of the emulsifier is 0.10%-0.50% w / w of the total amount of the raw materials, and the amount of the flavoring agent is 4%-12% w / w of the total amount of the raw materials; Preferably, the thickener is konjac gum, and the amount used is 0.2% of the total amount of raw materials; the emulsifier is glyceryl monostearate, and the amount used is 0.3% of the total amount of raw materials; the flavoring agent is xylitol, and the amount used is 10% of the total amount of raw materials.

10. Use of the pea starch-tea polyphenols complex according to any one of claims 1 to 4 and the miscellaneous grain powder according to any one of claims 6 to 9 in preparing antioxidant health foods or low glycemic index (GI) foods.

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