Method for preparing sweet soup balls based on glutinous rice flour with low grain breakage rate

Abstract

The invention discloses a method for preparing sweet soup balls based on glutinous rice flour with low grain breakage rate. Glutinous rice starch grains are operated through a production process flow of crushing and powdering by a soaking and rubbing method. The 100-mesh sieving rate of the prepared glutinous rice flour grains reaches 99.8% or above, the glutinous rice flour is finer and smoother, meanwhile, the granular starch breakage rate is stabilized to be smaller than 5%, the texture is improved, and the product quality is stable. The soup transmittance of the prepared glutinous rice dumplings is remarkably improved, the cooking loss rate, the floating time and the freezing cracking rate are remarkably reduced, the glutinous rice dumplings are easier to cook, and the cooked glutinous rice dumplings have better quality.

Description

Technical Field

[0001] The invention relates to a method for preparing glutinous rice balls based on glutinous rice flour with low grain breakage rate, and belongs to the technical field of food processing. Background Art

[0002] Tangyuan (glutinous rice balls) are a distinctive traditional Chinese delicacy, an indispensable delicacy during the Spring Festival and in everyday life. The market has continued to expand in recent years. With rising living and consumption standards, people are demanding higher quality glutinous rice balls. Improving the quality of glutinous rice balls primarily requires improving the glutinous rice flour. Existing technologies include enzymatic treatment to improve the properties of glutinous rice flour, but enzyme preparations are expensive and carry a risk of residues. Other methods involve chemical modification, but this method can pose safety concerns. If improvements can be made to the preparation process to enhance the properties of glutinous rice flour, later reprocessing of the flour can be avoided.

[0003] Common glutinous rice flour production processes currently include: Dry milling: This process involves directly grinding the raw rice grains through equipment such as claw mills, hammer mills, or airflow mills. While this method is simple, because the original caryopsis grains do not absorb sufficient water and the starch crystallite bundles in the grain aggregates are tightly bound, the starch breakage rate is too high, reaching 12-15%, due to external forces and high temperatures. This leads to problems such as sticking during production and the product texture does not meet quality standards. Glutinous rice balls made with glutinous rice flour prepared using dry milling tend to over-gelatinize after cooking, resulting in cracked skin and cloudy soup.

[0004] Semi-dry milling: Although the quality of semi-dry milling is better than that of dry milling, and its starch damage rate is reduced, the milling mechanism does not fully match the molecular cluster crystal properties formed by the caryopsis seed complex, resulting in unstable starch powder quality and high production costs. For example, in patent CN107080156A, a semi-dry milling method for preparing glutinous rice flour is used. After hot steam treatment, glutinous rice grains with cracks on the surface and transverse cracks extending deep into the rice grains are obtained; the moisture content of the glutinous rice grains is increased, and then the glutinous rice flour is obtained by grinding and drying. The two-step hot steam treatment in this method is costly, and the 100-mesh screening rate of the prepared product is 70%, and the quality needs to be further improved.

[0005] Wet grinding: It is the main process for preparing glutinous rice flour at present. Its process flow includes moderate soaking of raw grains, coarse grinding, standing, fine grinding, filter pressing and hot air drying. This method adopts stone mill or diamond grinding equipment. The advantages are that the particle size of caryopsis grains is relatively fine, the starch breakage rate is low, and the natural structure of starch can be maintained. The 100-mesh screening rate can reach more than 92%. Its product quality basically meets the processing quality requirements of glutinous rice flour. The glutinous rice balls prepared with this glutinous rice flour have a delicate taste, moderate viscosity, and relatively clear soup, but some performance still needs to be further improved; in addition, wet grinding has the problems of high energy consumption and high cost, and the amount of wastewater generated is large, which will also bring environmental sanitation problems. Moreover, if wet grinding is carried out with a stone mill, impurities such as stone sand are easily produced during the grinding process and brought into the product.

[0006] The current flour-making process cannot meet the needs of the industrial development of glutinous rice flour. There is an urgent need to develop a glutinous rice flour production process with stable product quality, further improved texture, and lower overall production cost. Summary of the Invention

[0007] In order to address the shortcomings of the existing technology, the present invention provides a glutinous rice starch grain grinding and flour making process using the "soaking and rubbing method". According to the properties of the raw materials and molecular structure, the process flow of preparing glutinous rice balls is determined as follows: glutinous rice → cleaning and fermentation → centrifugal dehydration → roller squeezing and crushing → air flow ultrafine grinding → drying → powder adjustment → molding → quick freezing → packaging.

[0008] The present invention is achieved through the following technical solutions:

[0009] A first object of the present invention is to provide a method for preparing glutinous rice flour with a low grain breakage rate, comprising the following steps:

[0010] S1, washing glutinous rice, adding water, inoculating Lactobacillus plantarum and Saccharomyces cerevisiae, adding CaCl2, and draining the water after natural fermentation;

[0011] S2, performing gradient centrifugal dehydration on the fermented glutinous rice grains using a filter centrifuge;

[0012] S3, squeezing and kneading the dehydrated glutinous rice grains using a two-roller machine;

[0013] S4, adding the squeezed glutinous rice powder into an airflow superfine grinder for superfine grinding;

[0014] S5, drying the ultrafinely crushed glutinous rice flour to obtain glutinous rice flour with a low grain breakage rate;

[0015] In one embodiment of the present invention, the amount of water added in step S1 is 1 to 2 times the amount of glutinous rice.

[0016] In one embodiment of the present invention, the inoculation amount of Lactobacillus plantarum and Saccharomyces cerevisiae in step S1 is 1% to 5%, wherein the ratio of Lactobacillus plantarum to Saccharomyces cerevisiae is 1 to 3:1.

[0017] In one embodiment of the present invention, the amount of CaCl2 added in step S1 is 0.1% to 0.5%.

[0018] In one embodiment of the present invention, the natural fermentation conditions in step S1 are 28° C. to 32° C. and the natural fermentation time is 1 hour to 30 hours.

[0019] In one embodiment of the present invention, in step S1, the water is drained for 5 to 25 minutes after fermentation.

[0020] In one embodiment of the present invention, the gradient centrifugation in step S2 is first centrifuged at 600 rpm to 1000 rpm for 2 min to 6 min, and then centrifuged at 1000 rpm to 1500 rpm for 2 min to 10 min.

[0021] In one embodiment of the present invention, in step S3, when the two-roller machine squeezes and rubs, the angle between the rollers is 3° to 7°, the rotation speed of the first-level roller is set to 40rpm to 700rpm, and the rotation speed of the second-level roller is set to 400rpm to 1200rpm.

[0022] In one embodiment of the present invention, in step S3, during the squeezing and kneading process of the two-roller machine, a cold air flow is provided between the primary roller and the secondary roller to reduce the temperature. Furthermore, the cold air flow is 10°C to 20°C and the wind speed is 1m / s to 3m / s.

[0023] In one embodiment of the present invention, in step S4, the parameters of ultrafine grinding are air flow pressure: 0.6MPa~1.0MPa, classification wheel speed 2000rpm~3000rpm, feed rate 40kg / h~60kg / h, and discharge particle size D50=48μm~150μm.

[0024] In one embodiment of the present invention, in step S5, the drying is performed using a hot air flow drying device, the drying temperature is 50° C. to 70° C., and the drying time is 1 hour to 5 hours.

[0025] The second object of the present invention is to provide glutinous rice flour with low grain breakage rate prepared by the method.

[0026] The third object of the present invention is to provide a glutinous rice flour with a low grain breakage rate for use in preparing glutinous rice balls.

[0027] In one embodiment of the present invention, the application is specifically to fully mix glutinous rice flour, shortening, emulsified oil and water to form dough, and further prepare glutinous rice balls.

[0028] In one embodiment of the present invention, 10kg to 30kg of glutinous rice flour, 1kg to 2kg of shortening, 1kg to 2kg of emulsified oil, and 10kg to 20kg of water are fully mixed, and the glutinous rice balls are formed and allowed to stand for 10min to 20min.

[0029] Beneficial effects of the present invention:

[0030] The present invention utilizes a "wet-rubbed" pulverization process to produce glutinous rice starch grains. This integrated production process fully integrates the quality standards and properties of glutinous rice products, meeting the characteristics of raw materials and molecular structure. It defines the industrial production process flow, along with the technical specifications for pulverization and milling equipment, production capacity, and other related indicators. This ensures the quality stability of glutinous rice fine grinding and milling. The grain size passes a 100-mesh sieving rate of over 99.8%, resulting in a finer glutinous rice flour. Furthermore, the granular starch breakage rate remains stable at less than 5%, improving texture and maintaining consistent product quality. Glutinous rice dumplings prepared using the glutinous rice flour prepared using the present invention exhibit significantly improved soup permeability, significantly reduced cooking loss, floating time, and freeze cracking, making the dumplings easier to cook and exhibiting improved quality after cooking. The low breakage rate and fine particle size ensure that the glutinous rice flour particles are intact and uniform, forming a dense glutinous rice dumpling skin structure, improving wrapping and swelling resistance, and reducing starch loss and structural breakdown during cooking, thereby lowering cooking loss. At the same time, the intact particles are resistant to moisture migration and aging, reducing microcracks and brittle cracks after freezing, significantly reducing the freezing cracking rate, and improving cooking and freezing stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 Flow chart for the preparation of glutinous rice flour. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with specific examples. These implementation cases are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims appended hereto.

[0034] Source of raw materials

[0035] The glutinous rice used in this application is Shulan glutinous rice, purchased from COFCO Group, with a moisture content of 12% to 14% and an amylose content of 1% to 5%. Lactobacillus plantarum and Saccharomyces cerevisiae were purchased from Shaanxi Baichuan Biotechnology.

[0036] Test method:

[0037] (1) Determination of glutinous rice flour damage rate:

[0038] Amperemetry: Instrument: Chopin SDmatic analyzer (with 35°C constant temperature reaction system, 1200 rpm stirrer), 1 / 10,000 balance. Detailed steps are as follows: Weigh 1g sample and add 50mL buffer. Mix with 1mL of 0.01mol / L iodine solution at 35°C for 10 minutes. Terminate with 8mL of 0.2% sulfuric acid. The instrument automatically detects the change in current and calculates the damaged starch value. Key parameters: temperature 35°C ± 0.5°C, stirring speed 1200 rpm ± 5 minutes, reaction time 10 minutes ± 0.5 minutes.

[0039] (2) Whiteness test method of glutinous rice flour:

[0040] Zero and calibrate the whiteness meter, then assemble the whiteboard components, fill each with glutinous rice flour sample, scrape it flat, and press the cover. Place the prepared flatboard in the calibrated whiteness meter to test the sample's whiteness. Repeat the measurement three times for each sample group and take the average value.

[0041] (3) Determination of water absorption of glutinous rice flour:

[0042] Accurately weigh 1 g of glutinous rice flour, add 100 g of deionized water, and mix evenly using a magnetic stirrer; take 15 mL of glutinous rice flour paste and pour it into a 50 mL centrifuge tube, freeze it in a -80°C freezer for 24 h, then take it out, thaw it to room temperature, and centrifuge it in a centrifuge at a speed of 5000 r / min for 20 min. Filter out excess water, weigh the centrifuge tube and the sediment, and calculate the water separation rate (R) according to the following formula.

[0043] R=[(m1—m2) / (m1—m0)]×100%

[0044] Where m0 is the mass of the centrifuge tube / g; m1 is the total mass of the centrifuge tube and sample after thawing / g; m2 is the total mass of the centrifuge tube and sediment after centrifugation / g.

[0045] (6) Determination of glutinous rice flour viscosity:

[0046] The sample was passed through a 0.42 mm sieve and the moisture content was determined according to GB / T 5497. Subsequently, 3.00 g of the sample was weighed and 25 mL of distilled water was added to the RVA sample cylinder for pre-dispersion. The sample was then pre-sheared at 50°C (960 rpm, 10 s) → heated to 95°C (6°C / min, 160 rpm) → maintained at 95°C → cooled to 50°C → recorded the curve, and finally analyzed and recorded the viscosity value.

[0047] (7) Determination of glutinous rice flour density:

[0048] Weigh 10 g of glutinous rice flour sample and place it in a dry graduated cylinder. Set the vibration instrument parameters to an amplitude of 3 mm and a frequency of 250 times / min. Record the volume (V1) after continuous vibration for 500 times.

[0049] Calculate volume density: ρ = m0 / V1

[0050] (8) Glutinous rice flour gelatinization properties test:

[0051] a. Determination of the Retrogradation of Glutinous Rice Paste: Weigh 3g of glutinous rice flour and prepare a 3% (w:w) solution. Heat in a boiling water bath for 30 minutes with constant shaking. After full gelatinization, pour the solution into a graduated test tube and let it stand at room temperature for 72 hours. Observe the changes in the paste layer and record the volume of the supernatant. The retrogradation property of the paste is expressed as the percentage of the supernatant volume to the total paste volume; a higher percentage indicates stronger retrogradation.

[0052] b. Determination of glutinous rice ball hardness: Weigh 10g of glutinous rice flour, add 9mL of distilled water, mix thoroughly, and form evenly sized rice balls. Steam the balls in an electric steamer for 20 minutes, remove them, and store them at room temperature for 72 hours before measuring their hardness. Hardness was measured using a texture analyzer with a P35 probe in TPA mode, a pre-test speed of 2.0mm / s, a test speed of 1mm / s, and a post-test speed of 10.0mm / s. The compression distance was 2.5mm (expressed in g). Hardness was defined as the maximum stress during the first compression cycle.

[0053] c. Comprehensive evaluation method: The anti-aging effect of glutinous rice flour was comprehensively evaluated by converting multiple indicators into a single indicator. The higher the comprehensive score, the higher the degree of aging of the glutinous rice flour and the worse the anti-aging performance; vice versa. The importance of settling and hardness is consistently correlated. Therefore, the comprehensive evaluation formula is used:

[0054] Comprehensive index = sedimentation (100%) × 100 + hardness

[0055] (10) Determination of gelatinization properties of glutinous rice flour (RVA method):

[0056] The viscosity curve of glutinous rice flour was measured using a German Viscograph-E Brabender viscometer, with the unit of viscosity being BU. 100 g of glutinous rice flour was weighed, and 150 mL of water was added at a ratio of 1:1.5. The mixture was mixed thoroughly and allowed to equilibrate in a sealed container for 3 hours. The sample was then pre-frozen in a -30°C refrigerator for 30 minutes, transferred to a -20°C freezer for 24 hours, and thawed to room temperature. The freeze-thaw cycles were repeated 1, 3, 5, and 10 times. The thawed sample was dried in a well-ventilated area for 24 hours, ground, and passed through a 100-mesh sieve. The glutinous rice flour emulsion was heated using a Brabender viscometer, and the viscosity change with temperature was continuously recorded.

[0057] (11) Determination of glutinous rice flour gel properties:

[0058] The hardness, adhesiveness, elasticity, chewiness, and recoverability of the samples were measured using a TA.XTPLUS texture analyzer. Glutinous rice flour was mixed with water to create a 10% glutinous rice paste. The test was performed using a P / 36R probe. The test conditions were a pre-test speed of 2 mm / s, a test speed of 1 mm / s, a post-test speed of 1 mm / s, a compression ratio of 70%, and a dwell time of 5 seconds between compressions.

[0059] (12) Steaming characteristics of glutinous rice balls:

[0060] Cooking loss rate: Take 10 glutinous rice balls (accurately weighed W, in g) and cook them in boiling water with a water bath ratio of 1:20 (glutinous rice balls: water). Maintain a gentle boil (98±1°C) until all the glutinous rice balls float. Continue cooking for 5 minutes, remove the glutinous rice balls, let the soup stand for 30 minutes, and then filter (using Whatman No. 1 filter paper). Transfer the filtrate to a constant weight evaporating dish and dry at 105°C to a constant weight (Wz). Cooking loss rate (%) = (W2 / W1) × 100

[0061] Soup transmittance: Collect the soup after cooking, let it stand at 4℃ for 1 hour, take the supernatant, filter it through a 0.45um microporous filter membrane, and measure the absorbance (A) at 660nm using a UV spectrophotometer. Transmittance (%) = 10^(2-A)×100

[0062] Floating time: Put 5 glutinous rice balls into a boiling water bath (1000 mL, 98 ± 1 ° C) at one time and use a stopwatch to record the time it takes for 50% of the glutinous rice balls to float (T 50 ) and total floating time (T 100 ) Repeat 3 times and take the average

[0063] Frozen cracking rate: Quick-freeze the stuffed glutinous rice balls at -35°C for 30 min (center temperature ≤ -18°C). Transfer them to a -18°C freezer for 7 days, then thaw naturally to 0°C. Observe the surface with a 10x magnifying glass. Cracking rate (%) = (number of cracked glutinous rice balls / total number of glutinous rice balls) × 100.

[0064] In the present application, the inventors utilized the properties of glutinous rice raw materials and the ridged microporous structure in starch crystals, that is, the channels and pores from the core cavity inside the starch granules to the surface of the granules, which can provide channels for water and enzymes. By adding Lactobacillus plantarum (L. plantarum) and Saccharomyces cerevisiae (S. cerevisiae) strains for mixed fermentation and adding CaCl2 at the same time, the fermentation treatment of glutinous rice by microorganisms can soften the glutinous rice structure and promote the decomposition of glutinous rice. CaCl2 can maintain the integrity of the cell wall structure and prevent excessive softening, allowing the grain starch granules to fully absorb water and soften, while the natural polysaccharide polycrystalline system composed of alternating amorphous layers and crystalline layers of the cell structure of the caryopsis starch granules is more fully unraveled, creating process conditions for subsequent crushing and fine grinding processes.

[0065] In the present application, the inventors used a centrifuge to remove some of the free water on the surface of the grain and between the pores of the particles, which helps reduce the risk of adhesion or flaking on the roller interface of the "roller equipment" and reduces the water content during the drying process. In actual operation, the glutinous rice after soaking and swelling has a relatively loose structure, and centrifugation is very easy to clog the filter, resulting in the inability to operate continuously and it is difficult to reduce the moisture content to about 30%. After a lot of experimental exploration, the inventors used the step-by-step centrifugation method of the present invention to achieve centrifugation of wet glutinous rice, successfully reducing the moisture content of glutinous rice to about 30%, and the equipment has low energy consumption and can be operated continuously. Compared with drying and dehydration, the operation time is greatly shortened and the energy consumption is greatly reduced.

[0066] In the present application, since the glutinous rice caryopsis grain aggregate has a “clustered” branching structure of ring patterns, it is basically composed of linear starch chains alternating crystalline and amorphous thin layers, and there are annular fine-grained crystal cells with gaps and their structures. After microbial treatment and water absorption expansion, its dense structure is evacuated and disintegrated along the annular fine lines of the pores. Then, by adjusting the gap between the rollers, the caryopsis grains are subjected to extrusion, rubbing and tearing stress, and disintegrated and broken into grains of different sizes (30 mesh 0.60mm-60 mesh 0.25mm). This operation is very consistent with the structural mechanism of the formation of caryopsis grains; it is beneficial to reduce breakage when separating starch granules, and it also avoids the number of collisions between the rotor and stator placed in the inner cavity of the airflow superfine grinder after the caryopsis grains are disintegrated and broken, which helps to greatly reduce the degree of starch damage during airflow superfine grinding. In addition, it is also beneficial to reduce the energy consumption of the airflow mill operating power.

[0067] The technical solutions of the present invention are described in detail below with reference to specific embodiments. In the following embodiments, unless otherwise specified, the reagents, materials and equipment used can be purchased from commercial sources, or prepared by conventional methods, or are commonly used in the industry.

[0068] Example 1:

[0069] The preparation process of glutinous rice flour of the present invention is as follows: glutinous rice → cleaning, fermentation → centrifugal dehydration → roller squeezing and crushing → air flow ultrafine grinding → drying. Figure 1 shown.

[0070] Specifically, the following steps are taken:

[0071] (1) After washing the raw glutinous rice, add 1.5 times the weight of the glutinous rice into water, inoculate 2% L. plantarum and 1% S. cerevisiae at an inoculum rate of 3% of the total weight, and add 0.3% CaCl2 (0.3g / 100mL). Stir well and place at 30°C for natural fermentation for 24 hours. After fermentation, drain for 10 minutes. At this time, the moisture content of the glutinous rice grains is measured to be about 45%;

[0072] (2) Dehydrating the fermented glutinous rice grains using a filter centrifuge. The centrifugation program was set as follows: first, centrifugation at 800 rpm for 5 min, then centrifugation at 1200 rpm for 8 min. After centrifugation, the moisture content of the glutinous rice grains was measured to be approximately 30%;

[0073] (3) The glutinous rice grains after centrifugation were squeezed and rubbed using a two-roller machine, wherein the speed of the first roller was set to 400 rpm, the speed of the second roller was set to 1000 rpm, the gap between the rollers was 0.5 mm, the deflection angle of the two roller axes was 3°, the cold air speed was 2 m / s, and the temperature was 20°C.

[0074] (4) adding the squeezed glutinous rice powder into an airflow superfine grinder for superfine grinding, wherein the parameters of the airflow superfine grinder are set to a grinding pressure of 0.7 MPa and a classifying wheel speed of 2500 rpm;

[0075] (5) The ultrafinely ground glutinous rice flour is dried using a hot air drying device at a drying temperature of 65° C. for 15 min. The glutinous rice flour with a moisture content of about 30% is dried to below 14%, and then stored in bags.

[0076] (6) 30 kg of glutinous rice flour, 2 kg of shortening, 2 kg of emulsified oil, and 20 kg of water were fully mixed to form a dough, which was then made into glutinous rice balls. After the glutinous rice balls were formed, they were allowed to stand for 20 minutes before use.

[0077] Example 2:

[0078] The preparation of glutinous rice flour specifically adopts following steps:

[0079] (1) After washing the raw glutinous rice, add 1.5 times the weight of the glutinous rice into water, inoculate 1% L. plantarum and 1% S. cerevisiae at an inoculum rate of 2% of the total weight, and add 0.3% CaCl2. After stirring evenly, place at 25°C for natural fermentation for 36 hours. After fermentation, drain for 10 minutes. At this time, the moisture content of the glutinous rice grains is measured to be about 45%;

[0080] (2) The fermented glutinous rice grains were dehydrated using a filter centrifuge, first centrifuged at 900 rpm for 3 minutes to remove surface water, and then centrifuged at 1500 rpm for 3 minutes. After centrifugation, the moisture content of the glutinous rice grains was measured to be about 28%;

[0081] (3) The glutinous rice grains after centrifugation were squeezed and rubbed using a two-roller machine, wherein the speed of the first roller was set to 300 rpm, the speed of the second roller was set to 1100 rpm, the gap between the rollers was 0.3 mm, the deflection angle of the two roller axes was 5°, the cold air speed was 2 m / s, and the temperature was 20°C.

[0082] (4) adding the squeezed glutinous rice powder into an airflow superfine grinder for superfine grinding, wherein the parameters of the airflow superfine grinder are set to a grinding pressure of 0.8 MPa and a classifying wheel speed of 3000 rpm;

[0083] (5) The ultrafinely ground glutinous rice flour is dried using a hot air drying device at a drying temperature of 65° C. for 15 min. The glutinous rice flour with a moisture content of about 30% is dried to below 14%, and then stored in bags.

[0084] (6) Thoroughly mix 30 kg of glutinous rice flour, 2 kg of shortening, 2 kg of emulsified oil, and 20 kg of water. After forming the glutinous rice balls, let them stand for 20 minutes before use.

[0085] Example 3:

[0086] The preparation of glutinous rice flour specifically adopts following steps:

[0087] (1) After washing the raw glutinous rice, add 1.5 times the weight of the glutinous rice into water, inoculate 3% L. plantarum and 1% S. cerevisiae at an inoculum rate of 4% of the total weight, and add 0.3% CaCl2. After stirring evenly, place at 30°C for natural fermentation for 20 hours. After fermentation, drain for 10 minutes. At this time, the moisture content of the glutinous rice grains is measured to be about 45%;

[0088] (2) Dehydrating the fermented glutinous rice grains using a filter centrifuge, first centrifuging at 600 rpm for 5 minutes to remove surface water, and then centrifuging at 1000 rpm for 5 minutes. After centrifugation, the moisture content of the glutinous rice grains was measured to be about 35%;

[0089] (3) The glutinous rice grains after centrifugation were squeezed and rubbed using a two-roller machine, wherein the speed of the first roller was set to 400 rpm, the speed of the second roller was set to 1200 rpm, the gap between the rollers was 0.3 mm, the cold air speed was 2 m / s, and the temperature was 20°C.

[0090] (4) adding the squeezed glutinous rice powder into an airflow superfine grinder for superfine grinding, wherein the parameters of the airflow superfine grinder are set to a grinding pressure of 0.6 MPa and a classifying wheel speed of 2000 rpm;

[0091] (5) The ultrafinely ground glutinous rice flour is dried using a hot air drying device at a drying temperature of 65° C. for 15 min. The glutinous rice flour with a moisture content of about 30% is dried to below 14%, and then stored in bags.

[0092] (6) Thoroughly mix 30 kg of glutinous rice flour, 2 kg of shortening, 2 kg of emulsified oil, and 20 kg of water. After forming the glutinous rice balls, let them stand for 20 minutes before use.

[0093] Comparative Example 1:

[0094] The step of "adding 0.3% CaCl2" in step (1) of Example 1 was omitted, and the other steps and parameters were consistent with Example 1.

[0095] Comparative Example 2:

[0096] The step (1) of Example 1, "inoculating 2% L. plantarum and 1% S. cerevisiae at an inoculum amount of 3% of the total weight" was omitted, and the other steps and parameters were consistent with Example 1.

[0097] Comparative Example 3:

[0098] The roller grinding step in step (3) of Example 1 was removed, and ultrafine grinding was directly performed after centrifugal dehydration. The other steps and parameters were consistent with Example 1.

[0099] Comparative Example 4:

[0100] The parameters of the airflow superfine pulverizer in step (4) of Example 1 were set to 1.0 MPa, the classifying wheel speed was 5000 rpm, and the other steps and parameters were consistent with Example 1.

[0101] Comparative Example 5:

[0102] The glutinous rice was crushed by a grinder to obtain glutinous rice coarse powder, and then crushed by a ball mill for 10 minutes to obtain glutinous rice flour prepared by a traditional method. The other steps and parameters were consistent with those in Example 1.

[0103] Result test example:

[0104] The glutinous rice flour prepared in Examples 1 to 3 and Comparative Examples 1 to 5 was subjected to the following tests. The test results are shown in Tables 1 to 3.

[0105] Table 1 Glutinous rice flour performance test results

[0106]

[0107]

[0108] Table 2 Gel properties of glutinous rice balls

[0109]

[0110] Table 3 Gelatinization properties of glutinous rice flour

[0111]

[0112] The results in Table 1 show that the starch damage rate of the glutinous rice flour prepared in the examples of the present invention was 3.8% to 4.5%, significantly lower than that of the comparative example. The 100-mesh sieving rate (99.6% to 99.9%), water absorption (1.75 g / g to 1.90 g / g), viscosity (1220 to 1350), whiteness (91.8 L* to 93.1 L*), and compactness (0.65 g / mL to 0.71 g / mL) were all significantly improved. This indicates that the glutinous rice flour prepared in the examples has a good texture and strong uniformity, and can effectively improve the performance of glutinous rice balls when subsequently used in the preparation of glutinous rice balls.

[0113] The results in Table 2 show that the glutinous rice flour prepared in the Examples of the present invention exhibited significantly higher hardness (1180 g to 1320 g), elasticity (0.79 mm to 0.85 mm), adhesion (-0.78 mJ to -0.92 mJ), and resilience (40.2% to 45.3%) than the comparative examples, with no significant change in gelation temperature. The glutinous rice flour prepared in the Examples of the present invention exhibits superior gelation properties and can improve product quality.

[0114] The results in Table 3 show that the gelatinization process of the glutinous rice flour prepared in the embodiment of the present invention is advanced, and the gelatinization enthalpy (9.9 J / g to 10.7 J / g) and the retrogradation enthalpy (6.1 J / g to 6.5 J / g) are significantly increased compared with the gelatinization enthalpy (7.3 J / g to 9.5 J / g) and the retrogradation enthalpy (3.5 J / g to 5.8 J / g) in the comparative example. This indicates that both starch gelatinization and retrogradation require higher energy. When used in the later stage of preparing glutinous rice balls, the retrogradation rate of the glutinous rice balls can be slowed down, thereby enhancing the quality and shelf life of the glutinous rice balls.

[0115] The glutinous rice dumplings prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were cooked separately. After the water was boiled, the glutinous rice dumplings were added and cooked until all the dumplings floated. The following tests were performed. The results are shown in Table 4.

[0116] Table 4 Glutinous Rice Ball Cooking Performance

[0117]

[0118] The results in Table 4 show that the glutinous rice dumplings prepared in the examples of the present invention have significantly higher soup permeability (87.3%T-91.2%T) than those in the comparative examples (45.2%T-65.3%T). Furthermore, the cooking loss rate (1.8%-2.5%), floating time (115s-125s), and freezing cracking rate (0%-5%) are significantly lower than those in the comparative examples (6.8s-12.3s, 185s-250s, and 35%-65%). This indicates that the dumplings are easier to cook and have better quality after cooking.

[0119] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing glutinous rice flour with low grain breakage rate, characterized in that: The steps include: S1, washing glutinous rice, adding water, inoculating Lactobacillus plantarum and Saccharomyces cerevisiae, adding CaCl2, and draining the water after natural fermentation; S2, performing gradient centrifugal dehydration on the fermented glutinous rice grains using a filter centrifuge; S3, squeezing and kneading the dehydrated glutinous rice grains using a two-roller machine; S4, adding the squeezed glutinous rice powder into an airflow superfine grinder for superfine grinding; S5, drying the ultrafinely crushed glutinous rice flour to obtain the glutinous rice flour with low grain breakage rate.

2. The preparation method according to claim 1, characterized in that In step S1, the inoculation amount of Lactobacillus plantarum and Saccharomyces cerevisiae is 1% to 5%, wherein the ratio of Lactobacillus plantarum to Saccharomyces cerevisiae is 1 to 3:

1.

3. The preparation method according to claim 1, characterized in that The amount of CaCl2 added in step S1 is 0.1% to 0.5%.

4. The preparation method according to claim 1, characterized in that In step S2, the gradient centrifugation is first performed at 600 rpm to 1000 rpm for 2 min to 6 min, and then at 1000 rpm to 1500 rpm for 2 min to 10 min.

5. The preparation method according to claim 1, characterized in that In step S3, when the two-roller machine is squeezing and rubbing, the angle between the rollers is 3° to 7°, the rotation speed of the first-level roller is set to 40rpm to 700rpm, and the rotation speed of the second-level roller is set to 400rpm to 1200rpm.

6. The preparation method according to claim 1, characterized in that In step S3, when the two-roller machine is squeezing and kneading, cold air of 10°C to 20°C is simultaneously introduced between the first roller and the second roller, with a wind speed of 1m / s to 3m / s.

7. The preparation method according to claim 1, characterized in that In step S4, the parameters of ultrafine grinding are air flow pressure: 0.6MPa~1.0MPa, classification wheel speed 2000rpm~3000rpm, feed rate 40kg / h~60kg / h, and discharge particle size D50=48μm~150μm.

8. The preparation method according to claim 1, characterized in that In step S5, the drying is performed using a hot air flow drying device, the drying temperature is 50° C. to 70° C., and the drying time is 1 hour to 5 hours.

9. Glutinous rice flour with low grain breakage rate prepared by the method according to any one of claims 1 to 8.

10. A glutinous rice dumpling prepared from the glutinous rice flour with low grain breakage rate according to claim 9.

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