Fresh-keeping rice flour prepared from new rice and preparation method thereof

Abstract

The application discloses a method for preparing fresh-keeping rice flour from new rice, and belongs to the technical field of agricultural product processing. The fresh wet rice flour is prepared from fresh indica rice, and after soaking and crushing, fermentation is carried out. A mixed solution of lauric acid and lipase is added to the fermented rice flour, and the material of the rice flour is adjusted. Then, the material of the rice flour is subjected to silk extrusion, aging, cutting, rehydration, packaging and sterilization treatment, so that the fresh-keeping rice flour is obtained. The fresh-keeping rice flour effectively solves the technical problems of too large viscosity, easy blockage of the rice flour machine, easy adhesion and high broken rice rate of the extruded rice flour when the rice flour is prepared from new rice, and solves the technical problems of slow rehydration of the rice flour and easy aging of the fresh rice flour by combining enzyme technology and changing the hydrophilicity and anti-aging performance of the new rice flour. The prepared fresh-keeping rice flour has the advantages of high nutrition, good flavor, convenient use, anti-aging and low broken rice rate.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing fresh-keeping rice flour with new rice, and belongs to the technical field of agricultural product processing. BACKGROUND

[0002] Rice flour is a popular traditional snack and is widely loved by consumers. In recent years, with the increasing attention to gluten-free food, rice flour is becoming more and more popular. The main raw material for preparing rice flour is indica rice, but using fresh indica rice as raw material cannot be well formed during the preparation of rice flour due to the weak gel strength of new rice, and is prone to broken pieces. When cooking rice flour, the soup is serious, and the rice flour is prone to broken pieces. Using aged rice as raw material can overcome the above problems, and indica rice aged for about one year is the most suitable. However, in the actual production process, in order to reduce production costs, many manufacturers even use indica rice aged for two or three years or even longer. During long-term storage, the rice may be moldy due to improper storage, and aflatoxin may be produced; long-term storage of aged rice produces "aged rice smell", and from the perspective of nutrition and health, indica rice aged for too long is not an ideal raw material for making rice flour.

[0003] At present, the main rice flour used on the market is dry rice flour, which has a long shelf life and is easy to package, transport and store. However, it needs to be soaked in water for a long time before use, and direct high-temperature cooking will cause uneven water absorption, resulting in surface mush and internal hard core. In recent years, with the development of food preservation technology, pre-packaged fresh and wet rice flour has attracted more and more attention, with a moisture content of 50-70%, hot water soaking for 3-5 minutes for instant consumption, and a shelf life of more than 6 months. However, during the production process of fresh and wet instant rice flour, the maintenance of rice flour quality (elasticity, toughness) is a problem that needs to be solved. With the extension of the storage time of rice flour, the rice flour will age, resulting in a decrease in water retention, broken pieces, a decrease in elasticity and toughness. The existing anti-aging methods include enzyme method, edible glue, modified starch, emulsifier, etc., but these methods are added before the formation of rice flour, which will affect the formation of gel by aging. If added after the formation, it can only penetrate from the surface of the rice flour, with poor effect, poor uniformity, and an impact on the smooth taste of the rice flour. SUMMARY

[0004] In view of the defects and deficiencies of the prior art, the present application provides a method for preparing fresh-keeping rice flour with new rice. The fresh-keeping rice flour prepared by the method has low cost, simple process, rice fragrance, no obvious sour taste, low broken piece rate and strong elasticity and toughness compared with the prior art.

[0005] The purpose of the present application is to provide a method for preparing fresh-keeping rice flour with new rice, which comprises the following steps:

[0006] (1) Raw material pretreatment: fresh indica rice is cleaned, soaked, drained, and crushed to obtain water-absorbed rice powder; the fresh indica rice is indica rice stored for less than 3 months after harvesting;

[0007] (2) Fermentation: the water-absorbed rice powder obtained in step (1) is fermented at room temperature for 2-4 days to obtain fermented rice powder;

[0008] (3) Formulation: lauric acid is dispersed in water, then lipase is added to form a mixed solution, and the moisture content of the fermented rice powder obtained in step (2) is adjusted to 28-35% using the mixed solution to obtain a formulated rice material;

[0009] (4) Extrusion: the formulated rice material obtained in step (3) is extruded to form a shaped rice powder;

[0010] (5) Aging and cutting: the shaped rice powder obtained in step (4) is aged and cut;

[0011] (6) Rehydration: the cut rice powder in step (5) is soaked in water at 75-85°C for 8-12 min, and then soaked in room temperature water for 2-4 min;

[0012] (7) Packaging and sterilization: the soaked rice powder in step (6) is packaged and sterilized, and cooled to room temperature to obtain fresh-keeping rice powder.

[0013] In one embodiment, the raw material in step (1) raw material pretreatment can also include fresh indica rice mixed with part of coarse grain powder; the coarse grain powder includes one or more of black rice powder, buckwheat powder, oat powder, corn powder, and purple sweet potato powder.

[0014] In one embodiment, the crushing in step (1) has a mesh size of 80-100 mesh.

[0015] In one embodiment, the addition of lauric acid in step (3) has a mass fraction of 0.5-1.5% of the dry weight of the indica rice.

[0016] In one embodiment, the dispersing of lauric acid in step (3) is assisted by a small amount of edible alcohol to dissolve the lauric acid, which is then dispersed in water.

[0017] In one embodiment, the addition of lipase in step (3) has a mass fraction of 0.1-0.3% of the dry weight of the indica rice.

[0018] In one embodiment, the extrusion in step (4) is a self-maturation type rice extrusion machine maturation molding, with an extrusion temperature of 75-85°C and a screw rotation speed of 180-200 rpm.

[0019] In one embodiment, the aging in step (5) is aging at a temperature of 50-55℃ and a relative humidity of 85-90% for 10-12 hours.

[0020] In one embodiment, the cutting in step (5) refers to cutting to a corresponding size according to the size requirement of the package.

[0021] In one embodiment, the metering in step (7) is 200-220g.

[0022] In one embodiment, the sterilization in step (7) is sterilization at 95-100℃ for 20-25 minutes.

[0023] A second object of the present application is to provide a fresh-keeping rice flour prepared by the above method, which has a shelf life of more than 1 year.

[0024] The beneficial effects of the present application are:

[0025] (1) The present application can effectively reduce the peak viscosity of starch gelatinization and the viscosity during aging by adding lauric acid to the new rice and forming starch-lipid complexes with amylose in the new rice during the extrusion process, thereby preventing the extruder from being blocked due to high viscosity and preventing the dispersion problem during aging. The formation of starch-lipid complexes can significantly improve the toughness of the rice flour and reduce the broken rice rate of the fresh-keeping rice flour. In addition, lauric acid is also an effective bacteriostatic agent that cooperates with organic acids produced during fermentation. Without adding organic acids, the rice flour has no obvious sour taste, and under the action of heat sterilization, it can effectively inhibit bacteria, so that the shelf life of the fresh-keeping rice flour can be more than 1 year.

[0026] (2) During the aging of the rice flour, the added lipase can gradually hydrolyze the lipids (mainly triglycerides) in the new rice to gradually produce diglycerides, fatty acids, and monoglycerides, which will not significantly affect the aging effect, but the product has a significant anti-aging effect on the fresh-keeping rice flour, avoiding the contradiction between the aging of the starch and the anti-aging requirement of the starch. During the storage and aging of rice, the fat will be oxidized and decomposed, which will affect the action of the lipase and reduce the action of the lipase. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with specific embodiments.

[0028] The determination method involved in the present application

[0029] 1. The pH value of the fresh-keeping rice flour is determined according to the method specified in GB5009.237-2016.

[0030] 2. The acidity of the fresh-keeping rice flour is determined according to the method specified in GB 5009.239.

[0031] 3. The broken rate of the fresh-keeping rice flour during extrusion is determined according to the method specified in CN 109907271 B.

[0032] 4. The cooked broken rate of the fresh-keeping rice flour is determined according to the method specified in the group standard T / CCOA 4-2019 Dry Rice Flour, with slight modifications: the sampling amount is changed to 200 grams of intact packaged product, and the cooked broken rate is defined as the percentage of the gram weight of 10 cm long rice flour after cooking to the total sampling amount.

[0033] 5. The shelf life of the fresh-keeping rice flour is determined according to the microbial indicators specified in DBS 45 / 050-2021, and if it exceeds the specified range, it is considered to exceed the shelf life.

[0034] The lipase used in the embodiment of the application is derived from the lipase of Aspergillus fungal microorganisms, and the enzyme activity is 15 KLU / g.

[0035] Example 1

[0036] A method for preparing fresh and wet rice flour from new rice, the method comprising the following steps:

[0037] (1) Raw material pretreatment: Take indica rice, wash, soak, drain, and crush to 100 mesh to obtain water-absorbed rice flour powder; the indica rice is indica rice stored for less than 3 months after harvesting;

[0038] (2) Fermentation: The water-absorbed rice flour powder obtained in step (1) is fermented at room temperature for 2 days to obtain fermented rice flour powder;

[0039] (3) Formulation: Dissolve lauric acid with a mass fraction of 1.5% (based on the dry weight of indica rice) in a small amount of edible alcohol, disperse in 10 times the volume of water, then add lipase with a mass fraction of 0.3% (based on the dry weight of indica rice) to the solution to form a mixed solution, and adjust the moisture content of the fermented rice flour powder of step (2) to 35% with the solution (the insufficient moisture is supplemented with pure water) to obtain a formulated rice flour material;

[0040] (4) Extrusion: The formulated rice flour material obtained in step (3) is cured and formed by a self-curing rice flour extruder, with an extrusion temperature of 75-85℃ and a screw speed of 200 rpm to obtain a formed rice flour;

[0041] (5) Aging: The formed rice flour obtained in step (4) is aged at 55℃ and a relative humidity of 90% for 10h, and then loosened to obtain a semi-dry rice flour;

[0042] (6) Cutting: cutting the semi-dry rice flour obtained in step (5) into 20 cm in length;

[0043] (7) Rehydration: soaking the cut rice flour in water at 75°C for 12 min and in room temperature water for 2 min.

[0044] (8) Packaging: packaging the soaked rice flour at 200 g per package;

[0045] (9) Sterilization: sterilizing the packaged rice flour at 95°C for 25 min; and rapidly cooling the sterilized rice flour to room temperature with cold water to obtain the fresh-keeping rice flour.

[0046] Example 2

[0047] A method for preparing fresh wet rice flour from new rice, comprising the following steps:

[0048] (1) Raw material pretreatment: washing, soaking, draining, and pulverizing indica rice to 80 mesh to obtain water-absorbed rice flour powder; the indica rice is indica rice stored for less than 3 months after harvesting;

[0049] (2) Fermentation: fermenting the water-absorbed rice flour powder obtained in step (1) at room temperature for 4 days to obtain fermented rice flour powder;

[0050] (3) Formulation: dissolving lauric acid with a mass fraction of 0.5% (based on the dry weight of indica rice) in a small amount of edible alcohol, dispersing in 10 times the volume of water, then adding lipase with a mass fraction of 0.1% (based on the dry weight of indica rice) to the solution to form a mixed solution, and adjusting the moisture content of the fermented rice flour powder of step (2) to 28% with the solution to obtain a formulated rice flour material;

[0051] (4) Extrusion: curing and forming the formulated rice flour material obtained in step (3) with a self-curing rice flour extruder, with an extrusion temperature of 75-85°C and a screw rotation speed of 200 rpm to obtain formed rice flour;

[0052] (5) Aging: aging the formed rice flour obtained in step (4) at 50°C and a relative humidity of 85% for 12 h, and loosening the strands to obtain semi-dry rice flour;

[0053] (6) Cutting: cutting the semi-dry rice flour obtained in step (5) into 25 cm in length;

[0054] (7) Rehydration: soaking the cut rice flour in water at 85°C for 8 min and in room temperature water for 4 min;

[0055] (8) Packaging: packaging the soaked rice flour at 220 g per package;

[0056] (9) Sterilization: sterilize the packaged rice flour at 100°C for 20 min; quickly cool the sterilized rice flour with cold water to room temperature to obtain the fresh-keeping rice flour.

[0057] Example 3

[0058] A method for preparing fresh and wet rice flour from new rice, the method comprising the following steps:

[0059] (1) Raw material pretreatment: wash, soak, and drain indica rice, and crush it to 100 mesh to obtain water-absorbed rice flour powder; the indica rice is indica rice stored for less than 3 months after harvesting;

[0060] (2) Fermentation: ferment the water-absorbed rice flour powder obtained in step (1) at room temperature for 3 days to obtain fermented rice flour powder;

[0061] (3) Formulation: dissolve 1.0% (based on the dry weight of indica rice) lauric acid in a small amount of edible alcohol, disperse it in 10 times the volume of water, then add 0.2% (based on the dry weight of indica rice) lipase to the solution to form a mixed solution, and use the solution to adjust the moisture content of the fermented rice flour powder of step (2) to 32% to obtain a formulated rice flour material;

[0062] (4) Extrusion: mature and form the formulated rice flour material obtained in step (3) using a self-maturing rice flour extruder, with an extrusion temperature of 75-85°C and a screw rotation speed of 200 rpm to obtain formed rice flour;

[0063] (5) Aging: age the formed rice flour obtained in step (4) at 52°C and a relative humidity of 88% for 11 h, and then loosen the strands to obtain semi-dry rice flour;

[0064] (6) Cutting: cut the semi-dry rice flour obtained in step (5) into lengths of 22 cm;

[0065] (7) Rehydration: soak the cut rice flour in water at 77°C for 10 min, and then soak it in cold water for 3 min;

[0066] (8) Packaging: measure 210 g of the soaked rice flour and package it;

[0067] (9) Sterilization: sterilize the packaged rice flour at 98°C for 22 min; quickly cool the sterilized rice flour with cold water to room temperature to obtain the fresh-keeping rice flour.

[0068] Comparative Example 1

[0069] Referring to the preparation method of the fresh-keeping rice flour described in CN 114365816 A, the specific steps are as follows:

[0070] (1) Fermentation: ferment early indica rice at 25°C for 72 h;

[0071] (2) Refining: refining was carried out according to the mass ratio of dry rice and water of 1.5:1, to obtain rice slurry;

[0072] (3) Mixing: corn starch was added into the rice slurry, and mixed uniformly to obtain a mixed solution; wherein the proportion of dry rice and corn starch in the rice slurry was 20:1;

[0073] (4) Gelatinization: the mixed solution was gelatinized at 100°C for 5 min to obtain a gelatinized solution;

[0074] (5) Extrusion molding: the gelatinized solution was extruded and molded by a full-automatic rice powder machine to obtain molded rice powder; wherein the extrusion temperature was 105°C;

[0075] (6) Aging: the molded rice powder was aged at 20°C and 80% humidity for 3 h to obtain aged rice powder;

[0076] (7) Rehydration: the aged rice powder was re-cooked in boiling water (100°C) for 5 min to obtain rehydrated rice powder;

[0077] (8) Thymol solution soaking: after cooling, the rehydrated rice powder was soaked in a thymol aqueous solution with a mass concentration of 0.03% at 25°C for 3 min; and then taken out;

[0078] 9) Packaging: bagging and heat sealing packaging in a sterile environment;

[0079] (10) High-temperature sterilization: the packaged fresh and wet rice powder was kept in a 90°C water bath environment for 30 min to obtain fermented fresh and wet rice powder.

[0080] Comparative Example 2

[0081] The fresh-keeping rice powder was prepared according to the method described in CN 109907271 B, and the specific steps were as follows:

[0082] S1, fresh potatoes were selected, washed, peeled, and cut into small pieces with a diameter of 0.8-1 cm by a dicing machine. Pure water was added to the potato pieces, and the mass ratio of the potato to the pure water was 2:1. The potato pieces were soaked for 30 min, and then coarsely ground by a grinding machine at a speed of 1000 revolutions per minute for 5 min;

[0083] S2, the coarsely ground potato slurry was uniformly ground by a colloid mill at a temperature of 25°C and a gap of 0.1 mm for 5 min. The uniformly ground potato slurry was dehydrated by a plate and frame press to a water content of 60%;

[0084] S3, adding corn starch, wheat starch, xanthan gum, CMC-Na and compound phosphate into the dehydrated potato pulp, then shearing and dispersing at 50℃ for 5 minutes by high-speed shearing disperser, rapidly cooling (within 10 seconds) to 20℃ by ice water bath for fluid aging, crosslinking time 12 minutes, obtaining potato mixture;

[0085] The raw materials used in the above preparation process are as follows in terms of weight fraction: fresh potato 80 parts, corn starch 6.5 parts, wheat starch 6.5 parts, xanthan gum 0.5 parts, CMC-Na 0.4 parts, compound phosphate 0.3 parts;

[0086] S4, according to the weight fraction of rice flour raw materials in step S3, 20 parts of indica rice is weighed, the indica rice is washed clean with water and then soaked at room temperature for 40 minutes, then taken out and drained, the indica rice is ground into rice flour of more than 100 mesh by a grinding machine, and then uniformly added into the potato mixture in step S3, while stirring, and then stirred at room temperature for 20 minutes, obtaining potato rice pulp;

[0087] S5, the uniformly mixed potato rice pulp is added into a tunnel type steamer for steaming, the steamer temperature is 102℃, and the steaming time is 4 minutes, completing the first curing;

[0088] S6, the cured potato rice pulp is stirred by a low-speed stirring machine at 50℃ for the second time of fluid crosslinking, the crosslinking time is 65 minutes, and then naturally fermented at 28℃ for 5 hours; 30,000 units of freeze-dried acidophilic lactobacillus 0.2g, 30,000 units of freeze-dried plant lactobacillus 0.6g and 10,000 units of freeze-dried wood acetic acid bacteria 0.2g are also added in the fermentation of the potato rice pulp;

[0089] S7, the fermented potato rice pulp is added into a double-screw rice flour machine, the double-screw rice flour machine is a full-automatic self-curing rice flour machine, the extrusion working device of the rice flour machine is a double screw, the rice flour machine includes a sleeve, a screw, an exhaust device and a die head, the two ends of the screw are connected with the die head and a gear box respectively, the exhaust device is installed on the sleeve close to the gear end of the screw, and the die plate aperture is φ1.0mm; the screw is divided into three sections, which are a conveying section, a shearing section and a compression section in sequence; the length ratio of the conveying section, the shearing section and the compression section is 1:2:2, and the compression ratio (V1 / V2) of the double screw is 5:1; the temperatures of the conveying section, the shearing section and the compression section are 100℃, 102℃ and 108℃ in sequence, and the time of the potato rice pulp uniformly passing through each temperature section is 10s, 20s and 20s in sequence; after the rice flour is extruded, the rice flour is uniformly cut into 100cm in length by an automatic cutting machine;

[0090] S8, the cut rice powder is gathered into a group, and is placed in 25℃ clean water containing 0.5% by mass of lactic acid. The soaked rice powder is scattered and the adhered rice powder is separated by using a filter screen. The separated rice powder is sealed and packaged, and is sterilized by steam at 121℃ for 5 minutes.

[0091] Comparative Example 3 (using old rice)

[0092] (1) Raw material pretreatment: long-stored indica rice is cleaned, soaked, drained, and pulverized to 100 mesh to obtain water-absorbed rice powder; the long-stored indica rice is indica rice that has been stored for more than 1 year after harvesting;

[0093] (2) Fermentation: the water-absorbed rice powder obtained in step (1) is fermented at room temperature for 2 days to obtain fermented rice powder;

[0094] (3) Formulation: 1.5% by mass (based on the dry weight of the indica rice) of lauric acid is dissolved in a small amount of edible alcohol, dispersed in 10 times the volume of water, and then 0.3% by mass (based on the dry weight of the indica rice) of lipase is added to the solution to form a mixed solution. The moisture content of the fermented rice powder of step (2) is adjusted to 35% using the mixed solution to obtain a formulated rice material;

[0095] (4) Extrusion: the formulated rice material obtained in step (3) is cooked and formed using a self-cooking rice extruder, with an extrusion temperature of 75-85℃ and a screw rotation speed of 200 rpm to obtain formed rice;

[0096] (5) Aging: the formed rice obtained in step (4) is aged at 55℃ and a relative humidity of 90% for 10 hours, and then is loosened to obtain semi-dry rice;

[0097] (6) Cutting: the semi-dry rice obtained in step (5) is cut into lengths of 23 cm;

[0098] (7) Rehydration: the cut rice is soaked in water at 75℃ for 12 minutes, and then is soaked in room temperature water for 2 minutes;

[0099] (8) Packaging: the rice is packaged in 200g per package;

[0100] (9) Sterilization: the packaged rice is sterilized at 95℃ for 25 minutes, and then is rapidly cooled to room temperature using cold water to obtain the fresh-keeping rice.

[0101] Comparative Example 4 (changing the type of fatty acid)

[0102] (1) Raw material pretreatment: long-stored indica rice is cleaned, soaked, drained, and pulverized to 100 mesh to obtain water-absorbed rice powder; the long-stored indica rice is indica rice that has been stored for less than 3 months after harvesting;

[0103] (2) Fermentation: the water-absorbed rice powder obtained in step (1) is fermented at room temperature for 2 days to obtain fermented rice powder;

[0104] (3) Formulation: 1.5% (by dry weight of indica rice) of oleic acid is dissolved in a small amount of edible alcohol, dispersed in water, and then 0.3% (by dry weight of indica rice) of lipase is added to the solution to form a mixed solution. The moisture content of the fermented rice powder of step (2) is adjusted to 35% with the solution to obtain a formulated rice material;

[0105] (4) Extrusion: the formulated rice material obtained in step (3) is cured and formed by a self-curing rice extruder, with an extrusion temperature of 75-85°C and a screw speed of 200 rpm to obtain a formed rice;

[0106] (5) Aging: the formed rice obtained in step (4) is aged at 55°C and a relative humidity of 90% for 10h, and then the rice is loosened to obtain semi-dry rice;

[0107] (6) Cutting: the semi-dry rice obtained in step (5) is cut into lengths of 22cm;

[0108] (7) Rehydration: the cut rice is soaked in water at 75°C for 12min and then in room temperature water for 2min;

[0109] (8) Packaging: the rice is packaged at a weight of 200g per package;

[0110] (9) Sterilization: the packaged rice is sterilized at 95°C for 25min, and then the sterilized rice is quickly cooled to room temperature with cold water to obtain the fresh-keeping rice.

[0111] Comparative Example 5 (changing the amount of fatty acid added)

[0112] (1) Raw material pretreatment: indica rice is washed, soaked, drained, and pulverized to 100 mesh to obtain water-absorbed rice powder; the indica rice is indica rice that has been stored for less than 3 months after harvesting;

[0113] (2) Fermentation: the water-absorbed rice powder obtained in step (1) is fermented at room temperature for 2 days to obtain fermented rice powder;

[0114] (3) Formulation: 0.3% (by dry weight of indica rice) of lauric acid is dissolved in a small amount of edible alcohol, dispersed in water, and then 0.3% (by dry weight of indica rice) of lipase is added to the solution to form a mixed solution. The moisture content of the fermented rice powder of step (2) is adjusted to 35% with the solution to obtain a formulated rice material;

[0115] (4) Extrusion: the prepared rice powder material in step (3) is matured and formed by using a self-maturation type rice powder extruder, the extrusion temperature is 75-85°C, the screw rotation speed is 200 rpm, and a shaped rice powder is obtained;

[0116] (5) Aging: the shaped rice powder obtained in step (4) is aged at 55°C and a relative humidity of 90% for 10 hours, the rice powder is loosened, and a semi-dry rice powder is obtained;

[0117] (6) Cutting: the semi-dry rice powder obtained in step (5) is cut into a length of 20 cm according to needs;

[0118] (7) Rehydration: the cut rice powder is soaked in water at 75°C for 12 minutes and in room temperature water for 2 minutes;

[0119] (8) Packaging: the rice powder is packaged at a weight of 200 g per package;

[0120] (9) Sterilization: the packaged rice powder is sterilized at 95°C for 25 minutes; the sterilized rice powder is rapidly cooled to room temperature with cold water, and a fresh-keeping rice powder is obtained.

[0121] Comparative Example 6 (changing the amount of added lipase)

[0122] (1) Raw material pretreatment: indica rice is washed, soaked, drained, and pulverized to 100 mesh to obtain a water-absorbed rice powder; the indica rice is indica rice that has been stored for less than 3 months after harvesting;

[0123] (2) Fermentation: the water-absorbed rice powder obtained in step (1) is fermented at room temperature for 2 days to obtain a fermented rice powder;

[0124] (3) Preparation: lauric acid with a mass fraction of 1.5% (based on the dry weight of indica rice) is dissolved in a small amount of edible alcohol, dispersed in water, and then lipase with a mass fraction of 0.05% (based on the dry weight of indica rice) is added to the solution to form a mixed solution; the water content of the fermented rice powder in step (2) is adjusted to 35% with the solution to obtain a prepared rice powder material;

[0125] (4) Extrusion: the prepared rice powder material in step (3) is matured and formed by using a self-maturation type rice powder extruder, the extrusion temperature is 75-85°C, the screw rotation speed is 200 rpm, and a shaped rice powder is obtained;

[0126] (5) Aging: the shaped rice powder obtained in step (4) is aged at 55°C and a relative humidity of 90% for 10 hours, the rice powder is loosened, and a semi-dry rice powder is obtained;

[0127] (6) Cutting: the semi-dry rice powder obtained in step (5) is cut into a length of 20 cm according to needs;

[0128] (7) Rehydration: cut rice powder was soaked in 75℃ water for 12 min, and in room temperature water for 2 min;

[0129] (8) Packaging: rice powder was measured 200g per package, and packaged;

[0130] (9) Sterilization: packaged rice powder was sterilized at 95℃ for 25 min; sterilized rice powder was rapidly cooled to room temperature with cold water, to obtain fresh-keeping rice powder.

[0131] Comparative Example 7 (without adding lipase treatment)

[0132] (1) Raw material pretreatment: indica rice was cleaned, soaked, drained, and crushed to 100 mesh to obtain water-absorbed rice powder; the indica rice was harvested and stored for less than 3 months;

[0133] (2) Fermentation: water-absorbed rice powder obtained in step (1) was fermented at room temperature for 2 days to obtain fermented rice powder;

[0134] (3) Formulation: lauric acid with a mass fraction of 1.5% (based on the dry weight of rice powder) was dissolved in a small amount of edible alcohol, dispersed in water to form a mixed solution, and used to adjust the moisture content of the fermented rice powder powder of step (2) to 35%, to obtain a formulated rice material;

[0135] (4) Extrusion: the formulated rice material obtained in step (3) was cured and formed by a self-curing rice extruder, with an extrusion temperature of 75~85℃ and a screw speed of 200 rpm, to obtain a formed rice;

[0136] (5) Aging: the formed rice obtained in step (4) was aged at 55℃ and a relative humidity of 90% for 10h, and then loosened to obtain semi-dry rice;

[0137] (6) Cutting: the semi-dry rice obtained in step (5) was cut into lengths of 20cm as needed;

[0138] (7) Rehydration: cut rice powder was soaked in 75℃ water for 12 min, and in cold water for 2 min;

[0139] (8) Packaging: rice powder was measured 200g per package, and packaged;

[0140] (9) Sterilization: packaged rice powder was sterilized at 95℃ for 25 min; cooling: sterilized rice powder was rapidly cooled to room temperature with cold water, to obtain fresh-keeping rice powder.

[0141] Results determination

[0142] 1. The performance indicators during the preparation of rice powder in Examples 1~3 and Comparative Examples 1~7 were determined, and the results of pH value, acidity and sensory evaluation are shown in Table 1:

[0143] Table 1. Determination of pH value, acidity and sensory evaluation of preserved rice flour

[0144]

[0145] From the results in Table 1, it can be seen that the preserved rice flour of the examples and the comparative examples all have a fermentation process during preparation. When the rice flour is fermented, organic acids are produced, which can lower the pH value of the rice flour, achieve the purpose of acidifying the rice flour, and improve the effect of high-temperature sterilization. With the extension of the fermentation time, the components such as protein in the rice flour will also be degraded, which will have a buffering effect on the pH value of the rice flour. That is, when the fermentation reaches a certain degree, the pH value of the rice flour does not change, but the organic acids produced by the fermentation will continue to accumulate, which will increase the acidity.

[0146] The process of Comparative Example 2 is to soak the rice flour in a lactic acid solution. The formula of the rice flour raw material of Comparative Example 2 is relatively complex. The wheat starch can increase the protein content of the rice flour. Both the protein and the compound phosphate have a buffering effect on the pH value. However, the protein, xanthan gum and CMC-Na have strong hydrophilicity, which can greatly increase the adsorption capacity of the rice flour to water and acid. Therefore, although the apparent pH value of Comparative Example 2 is not significantly different from that of other samples, the acidity is significantly increased, resulting in a significant sour taste of the rice flour in terms of both smell and taste.

[0147] Comparative Example 1 has a long fermentation time, which produces organic acids and relies on the sterilization effect of thymol solution for preservation. The product does not have a significant sour taste, but has a unique smell of thymol. Examples 1-3 and Comparative Examples 3-5 rely on the fermentation to produce a certain amount of organic acids, and no organic acids are introduced subsequently. The products retain the rice flavor and have no significant sour taste in terms of taste.

[0148] 2. The results of the determination of the broken strand rate of the preserved rice flour prepared in Examples 1-3 and Comparative Examples 1-7 after extrusion and rehydration are shown in Table 2:

[0149] Table 2. Determination results of broken strand rate of preserved rice flour

[0150]

[0151] From the results in Table 2, it can be seen that Examples 1-3 add lauric acid with a mass fraction of 0.5-1.5% to the new rice. Due to the formation of starch-lipid complex, the broken strand rate of the rice flour can be significantly reduced.

[0152] The anti-aging effect of Examples 1-3 is due to the formation of starch-lipid complex by fatty acid and amylose, and more importantly, the glycerol diester and glycerol monoester formed by the oxidation of lipids in the new rice material under the action of lipase, which has a long-term anti-aging effect on amylose and amylose during the shelf life of the preserved rice flour, and can significantly reduce the cooked broken rate of the rice flour. Comparative Example 1 does not take effective anti-aging measures, and the rice flour will quickly age during the shelf life, resulting in a high cooked broken rate. Comparative Example 2, although adding xanthan gum and CMC-Na and other colloids, has a certain anti-aging effect, but is added before the rice flour is formed, which will affect the aging forming effect of the rice flour. The strength of the rice flour formed by starch aging is insufficient, and although it has a certain elasticity and toughness in the early stage due to the action of the colloids, it will gradually form a hard gel under acidic conditions during the shelf life, thereby causing the product to quickly age during the shelf life and the broken rate to increase. Comparative Example 3 uses old rice as the raw material, and the lipids therein have been decomposed into more fatty acids during storage, which has a poorer anti-aging effect than glycerol diester and glycerol monoester. Comparative Examples 4 and 5 have a lower amount of starch-lipid complex formed, which has a poor effect on the early forming of the rice flour, and therefore has a higher broken rate. Comparative Examples 6 and 7 have a reduced amount of lipase added, which reduces the degradation of lipids and the anti-aging effect during the shelf life, and therefore has a higher broken rate.

[0153] 3. The shelf life of the preserved rice flour prepared in Examples 1-3 and Comparative Examples 1-7 was determined, and the results are shown in Table 3.

[0154] Table 3. Shelf life of preserved rice flour

[0155]

[0156] As can be seen from the results in Table 3, Examples 1-3 and Comparative Examples 3, 6, and 7 use lauric acid in combination with organic acids generated by fermentation, and both lauric acid and organic acids can be uniformly distributed inside and outside the rice flour, and combined with heat sterilization, the shelf life of the preserved rice flour can be more than 12 months. Comparative Example 1 uses thymol solution for soaking, which has a certain sterilization effect, but the effect of organic acids and heat sterilization is poor, and the shelf life is short. Comparative Example 4 uses oleic acid, and there is no report on the bacteriostatic effect of oleic acid, and only organic acids and heat sterilization have a sterilization effect. Comparative Example 5 uses a lower amount of lauric acid, and therefore the shelf life of Comparative Examples 4 and 5 is shorter than that of Examples 1-3.

[0157] The above examples are not intended to limit the scope of the present application, and the described steps are not intended to limit the execution order. Those skilled in the art can make obvious improvements to the present application based on existing common knowledge, which also falls within the protection scope defined by the claims of the present application.

Claims

1. A method for reducing the breakage rate of fresh rice noodles prepared from new rice, characterized in that, The method includes the following steps: (1) Raw material pretreatment: Take fresh indica rice, wash, soak, drain, and crush to obtain water-absorbing rice flour powder; the fresh indica rice is indica rice that has been stored for less than 3 months after harvest; (2) Fermentation: Ferment the water-absorbing rice flour powder obtained in step (1) at room temperature for 2 to 4 days to obtain fermented rice flour powder; (3) Preparation: Disperse lauric acid in water, then add lipase to form a mixed solution. Use this mixed solution to adjust the moisture content of the fermented rice flour powder obtained in step (2) to 28-35% to obtain the prepared rice flour material; the mass fraction of lauric acid added is 0.5-1.5% of the dry weight of indica rice; the mass fraction of lipase added is 0.1-0.3% of the dry weight of indica rice. (4) Extrusion: The rice flour material obtained in step (3) is extruded into shape to obtain shaped rice flour; (5) Aging and cutting: The shaped rice noodles obtained in step (4) are aged and cut. (6) Rehydration: Soak the rice noodles cut in step (5) in water at 75~85℃ for 8~12 minutes, and then soak them in room temperature water for 2~4 minutes; (7) Packaging and sterilization: The rice noodles soaked in step (6) are measured, packaged, sterilized, and cooled to room temperature to obtain fresh rice noodles.

2. The method according to claim 1, characterized in that, The raw materials in step (1) raw material pretreatment also include fresh indica rice mixed with some mixed grain powder; the mixed grain powder includes one or more of black rice powder, buckwheat powder, oat powder, corn powder, and purple sweet potato powder.

3. The method according to claim 1, characterized in that, The mesh size of the powder in step (1) is 80~100 mesh.

4. The method according to claim 1, characterized in that, In step (3), lauric acid is dispersed in water by using a small amount of edible alcohol to help dissolve the lauric acid before dispersing it in water.

5. The method according to claim 1, characterized in that, The extrusion molding in step (4) is performed by using a self-cooking rice noodle extruder for cooking and molding, with an extrusion temperature of 75~85℃ and a screw speed of 180-200rpm.

6. The method according to claim 1, characterized in that, The aging process described in step (5) is carried out at a temperature of 50-55℃ and a relative humidity of 85-90% for 10-12 hours.

7. The method according to claim 1, characterized in that, The sterilization in step (7) is performed at 95~100℃ for 20~25 minutes.

8. The preserved rice noodles prepared by the method according to any one of claims 1 to 7, characterized in that, The shelf life of the fresh rice noodles can reach more than one year.

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