Low-GI noodles and preparation method thereof

Abstract

The invention discloses noodles with the advantages of low GI value and quick cooking and a preparation method thereof. The noodles comprise the following components: purple highland barley whole flour, purple highland barley bran powder, wheat flour, vital gluten, high amylose corn starch and curdlan. The corresponding preparation method comprises the following steps: (1) preparing a plant lactobacillus suspension; (2) carrying out semi-solid state fermentation on composite purple highland barley powder (purple highland barley whole powder and purple highland barley bran powder) by adopting a plant lactic acid bacteria suspension; and (3) finely mixing dry and wet materials of the fermented composite purple highland barley powder and other materials, kneading dough, fermenting, calendering, cutting into strips, dehydrating and the like to prepare the purple highland barley noodles. Compared with conventional noodles, the obtained highland barley noodles belong to low-GI noodles (eGI = 44.9), can effectively control the postprandial blood sugar level of diabetics, are suitable for the diabetics to eat, are soft, elastic and smooth in taste, rich in dietary fibers and anthocyanin and high in nutritional value, and the cooking time is shortened by 30% or above.

Description

Technical Field

[0001] The invention belongs to the field of functional noodle processing, relates to the regulation of the glycemic index of noodles and the improvement of their quality, and specifically relates to low GI noodles and a preparation method thereof. Background Art

[0002] Diabetes is a chronic disease characterized by chronic hyperglycemia, which is not only accompanied by diffuse complications, but also increases the risk of premature death. Carbohydrates play a dominant role in the fluctuation of blood glucose concentration after meals, so managing the quality of carbohydrates in food is an effective way to control the high incidence of diabetes. Glycemic Index (GI) is a core indicator widely recognized in the field that can quantify the ability of carbohydrates in diet to increase blood glucose concentration after meals. The GI value of a food is usually characterized by the ratio of the integral area under the curve of the relationship between blood glucose concentration and time of the tested food within a certain period of time to the integral area under the curve of the standard food. Foods can be classified according to the size of the GI value, where foods with a GI value of >70 are high GI foods; foods with a GI value of <55 are low GI foods; and foods with a GI value between 55 and 70 are classified as medium GI foods. After low GI foods are ingested, the fluctuation of blood glucose concentration in the human body is small, which is beneficial to the blood glucose control of diabetic patients. Therefore, the eating habit of low GI foods is one of the effective means of preventing and treating diabetes. Compared with taking prescription drugs, dietary intervention can reduce the incidence and mortality of diabetes, and has significant advantages such as low cost, greenness and safety.

[0003] Phenolic compounds such as anthocyanins are a class of phytochemical active substances mainly located in the bran of cereals. They are rich in hydroxyl groups and have a strong affinity for starch digestive enzymes. They can delay starch digestion and control postprandial blood sugar levels by inhibiting the activity of digestive enzymes such as amylase and glycosidase. Regular intake of staple foods rich in phenolic compounds such as free anthocyanins can effectively reduce the risk of diabetes in the human body, and help to achieve steady-state control of postprandial blood sugar levels in diabetics, reducing the negative impact of high-carbohydrate staple diets. Highland barley is a colored grain rich in phenolic compounds such as anthocyanins. It is also known as a treasure trove of active compounds such as phenolic acids, flavonoids, and β-glucans. Whole grain staple foods processed with it have high potential nutritional value and functional properties. In particular, purple highland barley, compared with other colored highland barley, contains higher phenolic compounds such as anthocyanins, and is considered to be one of the most promising high-quality grain raw materials for the development of low glycemic index and special foods for diabetics. However, the cortex structure of purple barley is relatively thick, and 80% of anthocyanins and other phenolic compounds are bound in the fiber network structure in a bound form, with low bioavailability, resulting in a lower chance of contact with digestive enzymes.

[0004] Noodles are one of the staple foods of Chinese residents and are deeply loved by the general public. With the improvement of people's awareness of healthy eating and active health, functional healthy staple foods have become the vane of innovation and development in the staple food industry. Using purple barley flour as the main raw material, the development of high-quality highland barley noodles with low GI value has great practical significance. However, the development of functional staple foods of purple barley noodles still has the following technical bottlenecks: 1) Highland barley flour lacks gluten protein. In order to ensure the processing characteristics of the noodles, only a small amount of highland barley flour (<30%) can be added during the production of highland barley noodles, which cannot give highland barley noodles low GI value properties. 2) Phenolic substances such as anthocyanins in purple highland barley are mostly bound by structures and components such as cell walls and dietary fiber in the form of physical encapsulation or covalent bonding, and have low bioavailability. 3) The dietary fiber content in purple highland barley is as high as 18.16-21.46%, which reduces the palatability of noodles and makes them rough and hard. At the same time, the presence of a large amount of fiber reduces the gelatinization rate of starch in noodles, resulting in a long steaming time (>10min), which cannot meet the current demand for fast food delivery in the catering industry. This has always been an important factor restricting the rapid development of multi-grain noodles.

[0005] In order to solve the above technical bottleneck problems faced in the development process of low GI highland barley or grain noodles. At present, researchers have made innovative attempts in terms of raw material pretreatment, formulation, processing technology and equipment. For example, patent CN113875930A treats raw material powders such as highland barley flour with wet heat, mixes them with whole wheat flour, salt, and gluten improver, and prepares low GI whole grain highland barley noodles through dough kneading, cooking, rolling, and cutting. Although the invention increases the addition amount of highland barley flour to more than 50% and reduces the GI value of noodles to less than 55, the wet heat treatment causes the starch in the noodles to gelatinize in advance, resulting in a high cooking loss rate of highland barley noodles (>10%), and highland barley noodles have serious cooking breakage (cooking breakage rate>3.6%). Patent CN112869011A discloses a method for making low-GI grain noodles, which mainly adopts microwave pre-gelatinization, twin-screw extrusion and cooking pre-cooking. Although the proportion of grains reaches 100%, the starch undergoes continuous gelatinization, and starch aging occurs after drying and dehydration. Its production process is similar to that of dry vermicelli, which leads to an increase in the optimal cooking time of the noodles prepared therefrom (>7.5min), and a larger hardness, and poor chewiness and palatability. Patent CN109757647A discloses a formula of whole grains (highland barley flour, pea flour, buckwheat flour and quinoa flour), and adopts a process of extrusion pre-cooking followed by freezing aging treatment to prepare a highland barley low-GI extruded noodle, but the polyphenols, flavonoids and other bioactive substances in the prepared highland barley noodles are still mostly in the form of binding (accounting for >82% of the total amount). The high-temperature wet heat treatment, microwave pre-gelatinization treatment, twin-screw extrusion and steaming pre-cooking treatment proposed in the above-mentioned prior arts are all high-energy consumption processing methods, which are contrary to the current trend of the food industry to pursue low-carbon, low-energy consumption and green processing. Summary of the invention

[0006] [Technical issues]

[0007] In order to solve the shortcomings of the prior art such as low content of free phenolic active compounds (such as anthocyanins) and high energy consumption in the process of low GI highland barley products, the present invention develops and provides noodles with high content of free active compounds, low GI value and quick cooking, and a preparation method thereof.

[0008] [Technical solution]

[0009] The invention uses purple barley whole flour and purple barley bran flour as main raw materials, pioneers a semi-solid fermentation technology of plant lactobacillus suspension, and creates a strong resonance mixing technology of dry and wet materials, and further adds a certain proportion of high-amylose corn starch and curdlan, so as to give the barley noodles the functional attributes of a low GI staple food (eGI<55), and obtain a low GI purple barley noodle with short cooking time, quick cooking, and soft and elastic taste.

[0010] The specific technical solutions of the present invention are as follows:

[0011] A low GI noodle, the formula of which comprises the following components: composite purple barley flour, wheat flour, gluten powder, high-amylose corn starch, curdlan, plant lactobacillus, and water;

[0012] Wherein, the mass ratio of the composite purple barley flour to the wheat flour is (5-7): (1.5-3);

[0013] The composite purple barley flour is composed of purple barley whole flour and purple barley bran flour, and the mass ratio of the two is (6-49):1;

[0014] The dosage of Lactobacillus plantarum is 1×10 7 -10×10 7 CFU / kg compound purple barley powder.

[0015] In one embodiment of the present invention, the low GI refers to eGI<55.

[0016] In one embodiment of the present invention, the gluten powder accounts for 4wt%-10wt% of the total amount of the composite purple barley flour and wheat flour, and can be 5wt% specifically.

[0017] In one embodiment of the present invention, the high-amylose corn starch accounts for 1 wt%-15 wt% of the total amount of the composite purple highland barley flour and wheat flour, and can be specifically 10 wt%.

[0018] In one embodiment of the present invention, the curdlan accounts for 0.2wt%-1wt% of the total amount of the composite purple barley flour and wheat flour, and can be specifically 0.5wt%.

[0019] In one embodiment of the present invention, the amount of Lactobacillus plantarum is 7-8×10 7 CFU / kg compound purple barley powder.

[0020] In one embodiment of the present invention, the water content is 50%-70% of the total amount of the composite purple highland barley flour and wheat flour, and can further be 60%-65%.

[0021] A method for preparing noodles with low GI value and quick cooking, comprising the following steps:

[0022] (1) According to the above formula, the composite purple highland barley powder is first mixed with a portion of water, and then inoculated with a plant lactobacillus suspension, mixed and semi-solid fermented to obtain a purple highland barley flour paste;

[0023] (2) according to the above formula, wheat flour, gluten, high amylose corn starch, and a portion of water are mixed with the obtained purple highland barley flour to obtain mixed flour;

[0024] (3) According to the above formula, curdlan and the remaining water are mixed to form a curdlan suspension, which is then mixed with the mixed flour to prepare dough;

[0025] (4) allowing the dough to rise in a constant temperature and humidity environment, and then rolling and cutting into strips to form noodles; and then dehydrating the noodles to obtain purple highland barley noodles.

[0026] In one embodiment of the present invention, in step (1), the concentration of the Lactobacillus plantarum suspension is 1×10 7 -10×10 7 CFU / mL. Specific options are 5×10 7 CFU / mL.

[0027] In one embodiment of the present invention, in step (1), the mass fraction of water to the composite purple barley flour is 50% to 60%.

[0028] In one embodiment of the present invention, in step (1), the conditions for semi-solid fermentation are a temperature of 30° C. to 37° C. and a humidity of 70% to 80%.

[0029] In one embodiment of the present invention, in step (1), the semi-solid fermentation time is 2-12 hours, preferably 2-10 hours, and more preferably 8-10 hours.

[0030] In one embodiment of the present invention, in step (1), the Lactobacillus plantarum suspension can be obtained by the following method:

[0031] After the plant lactobacillus is placed in a sterilized MRS solid slant medium for passage and activation, 2 to 8 loops of bacterial bodies are inoculated into a sterilized MRS liquid medium, and cultured in a constant temperature shaking table (35°C, 120 to 180 r / min) for 2 to 6 days to prepare a plant lactobacillus activated bacterial seed solution, which is then dispensed into sterile centrifuge tubes, centrifuged at 4°C (10,000 r / min, 8 to 15 min), and the supernatant is discarded. The bacterial mud and sterilized physiological saline (concentration of 0.9%) are mixed by oscillation in a ratio of 1:1 to prepare a plant lactobacillus bacterial suspension.

[0032] In one embodiment of the present invention, in step (2), the mixing is carried out in a strong resonance mixer, and the vibration frequency is set to 150 to 300 times / min, the rotation speed is set to 150 to 200 r / min, and the amplitude is set to 5 to 10 mm.

[0033] In one embodiment of the present invention, in step (3), the kneading conditions are 120-200 r / min for 10-15 min.

[0034] In one embodiment of the present invention, in step (4), the proofing conditions are: temperature 25°C to 35°C, humidity 70% to 80%, time 1 to 4 hours

[0035] In one embodiment of the present invention, in step (4), the specific process of calendering includes: composite calendering twice at 2.0, 1.6, 1.2, and 0.9 mm spacings respectively, and single calendering once.

[0036] In one embodiment of the present invention, in step (4), the strips are cut using a 3 mm square knife.

[0037] In one embodiment of the present invention, in step (4), the dehydration treatment includes the following process:

[0038] Phase 1: temperature 30°C, humidity 75% to 85%, cycle frequency 35Hz, duration 20 to 40 minutes;

[0039] The second stage: temperature 40℃, humidity 70%-80%, cycle frequency 35Hz, duration 30-50min;

[0040] The third stage: temperature 45°C, humidity 60% to 70%, cycle frequency 35Hz, duration 80 to 120 minutes;

[0041] The fourth stage: temperature 25℃, humidity 55%-65%, cycle frequency 35Hz, duration 20-40min.

[0042] In one embodiment of the present invention, the preparation method specifically comprises:

[0043] (1) According to the above formula, purple barley whole flour and purple barley bran flour are mixed into composite purple barley flour; the composite purple barley flour is water-conditioned with sterile water to control its moisture content to 50% to 60%, and purple barley flour paste is prepared; then, a plant lactobacillus suspension is inoculated, the mixture is stirred and mixed evenly, and the purple barley flour paste is fermented for 2-12 hours at a temperature of 30° C. to 37° C. and a humidity of 70% to 80%;

[0044] (2) According to the above formula, wheat flour, gluten, high amylose corn starch, sterile water and all the purple highland barley flour paste after semi-solid fermentation in step (1) are placed in a strong resonance mixer, the vibration frequency is set to 150-300 times / min, the speed is 150-200r / min, the amplitude is 5-10mm, and the dry and wet materials are finely mixed to obtain mixed flour flocs; the water content is 40%-50%);

[0045] (3) Dissolving curdlan in water according to the above formula to prepare a curdlan suspension; pouring the curdlan suspension and all the mixed dough prepared in step (2) into a dough mixer for kneading (120-200 r / min, 10-15 min) to prepare dough (water content 55%-65%);

[0046] (4) The dough is placed in a constant temperature and humidity chamber for proofing for 1 to 4 hours (temperature 25°C to 35°C, humidity 70% to 80%), and then compound rolled twice at 2.0, 1.6, 1.2, and 0.9 mm spacings, and single pressed once, and finally cut into strips with a 3 mm square knife. The noodles are placed in an intelligent stage dehydrator for dehydration under the following conditions: first stage: temperature 30°C, humidity 75% to 85%, cycle frequency 35 Hz, duration 20 to 40 min; second stage: temperature 40°C, humidity 70% to 80%, cycle frequency 35 Hz, duration 30 to 50 min; third stage: temperature 45°C, humidity 60% to 70%, cycle frequency 35 Hz, duration 80 to 120 min; fourth stage: temperature 25°C, humidity 55% to 65%, cycle frequency 35 Hz, duration 20 to 40 min, to obtain purple highland barley noodles.

[0047] Further,

[0048] The Lactobacillus plantarum strain is HH-LP56.

[0049] MRS liquid culture medium consists of 0.8-1.5 g glucose, 0.6-1.0 g yeast extract, 1.2-1.5 g broth, 0.2-0.4 g NaCl, 0.2-0.3 g K 2 HPO 4 , 0.06~0.1g MgSO 4 7H 2 O, 0.006~0.01g MnSO 4 ·4H 2 O, 0.001~0.003gFeSO 4 7H 2 O composition.

[0050] For MRS solid slant culture, 1.2 to 1.8 g of agar was added to the liquid medium.

[0051] 3 to 6 circles of Lactobacillus plantarum cells, oscillation frequency 120 to 160 r / min, culture 2 to 5 days, centrifugation 10 to 15 minutes.

[0052] In step (1), the semi-solid fermentation conditions are: fermentation for 4 to 10 hours at a temperature of 33° C. to 35° C. and a humidity of 75% to 80%.

[0053] In step (4), the dough is proofed for 1 to 3 hours, the temperature is set at 30° C. to 35° C., and the humidity is set at 75% to 80%.

[0054] In step (4), the dehydration conditions are:

[0055] Phase 1: temperature 30°C, humidity 78%-82%, cycle frequency 35Hz, duration 30-40min;

[0056] The second stage: temperature 40℃, humidity 75%-80%, cycle frequency 35Hz, duration 40-50min;

[0057] The third stage: temperature 45°C, humidity 65% ​​to 70%, cycle frequency 35Hz, duration 90 to 110 minutes;

[0058] The fourth stage: temperature 25℃, humidity 60%-65%, cycle frequency 35Hz, duration 30-40min.

[0059] Beneficial effects:

[0060] [1] Compared with the high GI value, excessive energy consumption and insufficient nutrition of the coarse grain noodles prepared by the existing processing technology, the low GI purple highland barley noodles preparation method created by the present invention belongs to the green, energy-saving and nutritious coarse grain noodles bioprocessing technology. The semi-solid fermentation technology of whole highland barley flour and highland barley bran flour created by the present invention is a biotechnology in which probiotic microorganisms ferment on a natural semi-solid matrix (composite highland barley flour). No additional heat or energy input is required during the fermentation process. In addition, the probiotics not only metabolize and accumulate functional prebiotic components (exopolysaccharides, biological enzymes, amino acids, etc.), but also accurately degrade the dense fiber structure in the highland barley bran, so that the structural polyphenols (bound anthocyanins, protocatechuic acid, etc.) in the bran are fully freed, and the released nutritional functional factors are more easily absorbed by the human body after meals. In addition, compared with the existing multi-grain noodles that are insufficient in regulating postprandial blood sugar in diabetic patients, the released free polyphenols can inactivate the enzymatic activity of starch digestive enzymes such as α-amylase, thereby enhancing the anti-digestive properties of starch in highland barley noodles. The prepared highland barley noodles have a low glycemic index (GI=44.9) and have excellent ability to control postprandial blood sugar in diabetic patients, filling the gap in domestic green processing technology for low-GI noodles specifically for diabetic patients.

[0061] [2] Compared with the rough texture of the multi-grain noodles prepared by the existing processing technology, the water conditioning treatment of the composite purple highland barley flour in the preparation stage of semi-solid fermentation in the present invention plays a pre-hydration role, effectively weakens the competitive water absorption capacity of the fiber components in the composite purple highland barley flour, and weakens its deterioration effect on the protein network structure in the noodles. In addition, during the semi-solid fermentation process, under the influence of the enhanced activity of non-starch polysaccharide hydrolase and the increase in the acidity of the system, the larger and complete dietary fiber structure is gradually destroyed and broken into small fiber fragments, which effectively reduces the physical interference and destruction of the fiber structure on the protein network structure in the highland barley noodles. Under the premise of ensuring that the highland barley noodles are high-fiber noodles, they are truly soft and chewy in taste, and are deeply loved by consumers.

[0062] [3] Compared with the long cooking time of the multi-grain noodles prepared by the existing processing technology, the semi-solid fermentation processing technology proposed in the present invention cleverly uses plant lactobacillus to change the physicochemical properties of the starch components in the composite purple highland barley flour through acid and enzyme production, and changes the thermodynamic and gelatinization properties of the starch. In addition, under the synergistic effect of amylase decomposition and organic acid erosion, the structure of the starch granules is destroyed, and obvious cracks appear on the surface, forming a channel structure. The formation of this channel greatly promotes the rapid diffusion of water into the starch granules during the cooking process, improves the heat and mass transfer efficiency between starch and water, significantly shortens the optimal cooking time of highland barley noodles, and gives the multi-grain highland barley noodles the advantage of fast cooking. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a comparative observation of the dietary fiber structure in the purple highland barley noodles prepared in the comparative example and the example using a confocal laser scanning microscopy (CLSM).

[0064] Figure 2 This is a comparison of the effects of purple highland barley noodles prepared in the comparative example and the example on the activity of starch digestive enzymes.

[0065] Figure 3 This is a comparative observation of starch granules in the purple highland barley noodles prepared in the comparative example and the example using a scanning electron microscope (SEM).

[0066] Figure 4 It is a comparison of the starch gelatinization rates in the purple highland barley noodles prepared in the comparative example and the example. DETAILED DESCRIPTION

[0067] To facilitate the understanding of the formulations and techniques involved in the present invention by those skilled in the art, the present invention is further described in detail below in conjunction with comparative examples, embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0068] Embodiment 1:

[0069] A method for preparing low GI, quick-cooking purple highland barley noodles comprises the following steps:

[0070] (1) 6 g of Lactobacillus plantarum (HH-LP56) was sterilized on MRS solid slant medium (0.9 g glucose, 1.3 g agar, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06g MgSO 4 7H 2 O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2 After subculture activation, three loops of cells were inoculated into sterilized MRS liquid medium (0.9 g glucose, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06gMgSO 4 7H 2 O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2 O), cultured in a constant temperature shaking shaker (35°C, 120r / min) for 2d to prepare Lactobacillus plantarum activated bacteria seed solution, which was then dispensed into sterile centrifuge tubes and centrifuged at 4°C (10,000r / min, 10min) before discarding the supernatant. The bacterial mud and sterile physiological saline (0.9% concentration) were mixed by oscillation at a ratio of 1:1 to prepare a Lactobacillus plantarum suspension (the concentration of the bacterial suspension was 5×10 7 CFU / mL).

[0071] (2) 6.86 kg of purple barley whole powder and 0.14 kg of purple barley bran powder were mixed to form composite purple barley powder. The composite purple barley powder was conditioned with 3.5 kg of sterile water, and then inoculated with 10 mL of the plant lactobacillus suspension (5 × 10 7 CFU / mL), fully stirred and mixed, and fermented at 33°C and 75% humidity for 2h to obtain purple highland barley semi-solid fermentation slurry.

[0072] (3) placing all the purple highland barley semi-solid fermentation slurry obtained in step (2), 3 kg of wheat flour, 0.45 kg of gluten, 1.2 kg of high-amylose corn starch, and 1.7 kg of deionized water in a strong resonance mixer, setting the vibration frequency to 150 times / min, the speed to 150 r / min, and the amplitude to 5 mm, and finely mixing the dry and wet materials to obtain mixed flour.

[0073] (4) 0.05 kg of curdlan was dissolved in 1.2 kg of deionized water to prepare a curdlan suspension, which was then poured into a dough mixer with mixed flour to knead the dough (120 r / min, 10 min) to obtain dough.

[0074] (5) The dough was placed in a constant temperature and humidity chamber for proofing for 1 hour (temperature 30°C, humidity 75%), and then composite rolled twice at 2.0, 1.6, 1.2, and 0.9 mm spacings, and single pressed once, and finally cut into strips with a 3 mm square knife. The noodles were placed in an intelligent stage dehydrator for dehydration under the following conditions: first stage: temperature 30°C, humidity 78%, cycle frequency 35 Hz, duration 40 min; second stage: temperature 40°C, humidity 75%, cycle frequency 35 Hz, duration 50 min; third stage: temperature 45°C, humidity 65%, cycle frequency 35 Hz, duration 100 min; fourth stage: temperature 25°C, humidity 60%, cycle frequency 35 Hz, duration 40 min, to obtain purple highland barley noodles.

[0075] Embodiment 2:

[0076] A method for preparing low GI, quick-cooking purple highland barley noodles comprises the following steps:

[0077] (1) 6 g of Lactobacillus plantarum (HH-LP56) was sterilized on MRS solid slant medium (0.9 g glucose, 1.3 g agar, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06g MgSO 4 7H 2 O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2 After subculture activation, three loops of cells were inoculated into sterilized MRS liquid medium (0.9 g glucose, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06gMgSO 4 7H 2O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2 O), cultured in a constant temperature shaking shaker (35°C, 120r / min) for 2d to prepare Lactobacillus plantarum activated bacteria seed solution, which was then dispensed into sterile centrifuge tubes and centrifuged at 4°C (10,000r / min, 10min) before discarding the supernatant. The bacterial mud and sterile physiological saline (0.9% concentration) were mixed by oscillation at a ratio of 1:1 to prepare a Lactobacillus plantarum suspension (the concentration of the bacterial suspension was 5×10 7 CFU / mL).

[0078] (2) 6.86 kg of purple barley whole powder and 0.14 kg of purple barley bran powder were mixed to form composite purple barley powder. The composite purple barley powder was conditioned with 3.5 kg of sterile water, and then inoculated with 10 mL of the plant lactobacillus suspension (5 × 10 7 CFU / mL), and fermented at 33°C and 75% humidity for 4 h to obtain purple highland barley semi-solid fermentation slurry.

[0079] (3) placing all the purple highland barley semi-solid fermentation slurry obtained in step (2), 3 kg of wheat flour, 0.5 kg of gluten, 1.0 kg of high-amylose corn starch, and 1.7 kg of deionized water in a strong resonance mixer, setting the vibration frequency to 150 times / min, the speed to 150 r / min, and the amplitude to 5 mm, and finely mixing the dry and wet materials to obtain mixed flour.

[0080] (4) 0.05 kg of curdlan was dissolved in 1.2 kg of deionized water to prepare a curdlan suspension, which was then poured into a dough mixer with mixed flour to knead the dough (120 r / min, 10 min) to obtain dough.

[0081] (5) The dough was placed in a constant temperature and humidity chamber for proofing for 1 hour (temperature 30°C, humidity 75%), and then composite rolled twice at 2.0, 1.6, 1.2, and 0.9 mm spacings, and single pressed once, and finally cut into strips with a 3 mm square knife. The noodles were placed in an intelligent stage dehydrator for dehydration under the following conditions: first stage: temperature 30°C, humidity 78%, cycle frequency 35 Hz, duration 40 min; second stage: temperature 40°C, humidity 75%, cycle frequency 35 Hz, duration 50 min; third stage: temperature 45°C, humidity 65%, cycle frequency 35 Hz, duration 100 min; fourth stage: temperature 25°C, humidity 60%, cycle frequency 35 Hz, duration 40 min, to obtain purple highland barley noodles.

[0082] Embodiment 3:

[0083] A method for preparing low GI, quick-cooking purple highland barley noodles comprises the following steps:

[0084] (1) 6 g of Lactobacillus plantarum (HH-LP56) was sterilized on MRS solid slant medium (0.9 g glucose, 1.3 g agar, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06g MgSO 4 7H 2 O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2 After subculture activation, three loops of cells were inoculated into sterilized MRS liquid medium (0.9 g glucose, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06gMgSO 4 7H 2 O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2 O), cultured in a constant temperature shaking shaker (35°C, 120r / min) for 2d to prepare Lactobacillus plantarum activated bacteria seed solution, which was then dispensed into sterile centrifuge tubes and centrifuged at 4°C (10,000r / min, 10min) before discarding the supernatant. The bacterial mud and sterile physiological saline (0.9% concentration) were mixed by oscillation at a ratio of 1:1 to prepare a Lactobacillus plantarum suspension (the concentration of the bacterial suspension was 5×10 7 CFU / mL).

[0085] (2) 6.86 kg of purple barley whole powder and 0.14 kg of purple barley bran powder were mixed to form composite purple barley powder. The composite purple barley powder was conditioned with 3.5 kg of sterile water, and then inoculated with 10 mL of the plant lactobacillus suspension (5 × 10 7 CFU / mL), and fermented at 33°C and 75% humidity for 6 h to obtain purple highland barley semi-solid fermentation slurry.

[0086] (3) placing all the purple highland barley semi-solid fermentation slurry obtained in step (2), 3 kg of wheat flour, 0.5 kg of gluten, 1.0 kg of high-amylose corn starch, and 1.7 kg of deionized water in a strong resonance mixer, setting the vibration frequency to 150 times / min, the speed to 150 r / min, and the amplitude to 5 mm, and finely mixing the dry and wet materials to obtain mixed flour.

[0087] (4) 0.05 kg of curdlan was dissolved in 1.2 kg of deionized water to prepare a curdlan suspension, which was then poured into a dough mixer with mixed flour to knead the dough (120 r / min, 10 min) to obtain dough.

[0088] (5) The dough was placed in a constant temperature and humidity chamber for proofing for 1 hour (temperature 30°C, humidity 75%), and then composite rolled twice at 2.0, 1.6, 1.2, and 0.9 mm spacings, and single pressed once, and finally cut into strips with a 3 mm square knife. The noodles were placed in an intelligent stage dehydrator for dehydration under the following conditions: first stage: temperature 30°C, humidity 78%, cycle frequency 35 Hz, duration 40 min; second stage: temperature 40°C, humidity 75%, cycle frequency 35 Hz, duration 50 min; third stage: temperature 45°C, humidity 65%, cycle frequency 35 Hz, duration 100 min; fourth stage: temperature 25°C, humidity 60%, cycle frequency 35 Hz, duration 40 min, to obtain purple highland barley noodles.

[0089] Embodiment 4:

[0090] A method for preparing low GI, quick-cooking purple highland barley noodles comprises the following steps:

[0091] (1) 6 g of Lactobacillus plantarum (HH-LP56) was sterilized on MRS solid slant medium (0.9 g glucose, 1.3 g agar, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06g MgSO 4 7H 2 O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2 After subculture activation, three loops of cells were inoculated into sterilized MRS liquid medium (0.9 g glucose, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06gMgSO 4 7H 2O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2 O), cultured in a constant temperature shaking shaker (35°C, 120r / min) for 2d to prepare Lactobacillus plantarum activated bacteria seed solution, which was then dispensed into sterile centrifuge tubes and centrifuged at 4°C (10,000r / min, 10min) before discarding the supernatant. The bacterial mud and sterile physiological saline (0.9% concentration) were mixed by oscillation at a ratio of 1:1 to prepare a Lactobacillus plantarum suspension (the concentration of the bacterial suspension was 5×10 7 CFU / mL).

[0092] (2) 6.86 kg of purple barley whole powder and 0.14 kg of purple barley bran powder were mixed to form composite purple barley powder. The composite purple barley powder was conditioned with 3.5 kg of sterile water, and then inoculated with 10 mL of the plant lactobacillus suspension (5 × 10 7 CFU / mL), and fermented at 33°C and 75% humidity for 8 h to obtain purple highland barley semi-solid fermentation slurry.

[0093] (3) placing all the purple highland barley semi-solid fermentation slurry obtained in step (2), 3 kg of wheat flour, 0.5 kg of gluten, 1.0 kg of high-amylose corn starch, and 1.7 kg of deionized water in a strong resonance mixer, setting the vibration frequency to 150 times / min, the speed to 150 r / min, and the amplitude to 5 mm, and finely mixing the dry and wet materials to obtain mixed flour.

[0094] (4) 0.05 kg of curdlan was dissolved in 1.2 kg of deionized water to prepare a curdlan suspension, which was then poured into a dough mixer with mixed flour to knead the dough (120 r / min, 10 min) to obtain dough.

[0095] (5) The dough was placed in a constant temperature and humidity chamber for proofing for 1 hour (temperature 30°C, humidity 75%), and then composite rolled twice at 2.0, 1.6, 1.2, and 0.9 mm spacings, and single pressed once, and finally cut into strips with a 3 mm square knife. The noodles were placed in an intelligent stage dehydrator for dehydration under the following conditions: first stage: temperature 30°C, humidity 78%, cycle frequency 35 Hz, duration 40 min; second stage: temperature 40°C, humidity 75%, cycle frequency 35 Hz, duration 50 min; third stage: temperature 45°C, humidity 65%, cycle frequency 35 Hz, duration 100 min; fourth stage: temperature 25°C, humidity 60%, cycle frequency 35 Hz, duration 40 min, to obtain purple highland barley noodles.

[0096] Embodiment 5:

[0097] A method for preparing low GI, quick-cooking purple highland barley noodles comprises the following steps:

[0098] (1) 6 g of Lactobacillus plantarum (HH-LP56) was sterilized on MRS solid slant medium (0.9 g glucose, 1.3 g agar, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06g MgSO 4 7H 2 O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2 After subculture activation, three loops of cells were inoculated into sterilized MRS liquid medium (0.9 g glucose, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06gMgSO 4 7H 2 O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2 O), cultured in a constant temperature shaking shaker (35°C, 120r / min) for 2d to prepare Lactobacillus plantarum activated bacteria seed solution, which was then dispensed into sterile centrifuge tubes and centrifuged at 4°C (10,000r / min, 10min) before discarding the supernatant. The bacterial mud and sterile physiological saline (0.9% concentration) were mixed by oscillation at a ratio of 1:1 to prepare a Lactobacillus plantarum suspension (the concentration of the bacterial suspension was 5×10 7 CFU / mL).

[0099] (2) 6.86 kg of purple barley whole powder and 0.14 kg of purple barley bran powder were mixed to form composite purple barley powder. The composite purple barley powder was conditioned with 3.5 kg of sterile water, and then inoculated with 10 mL of the plant lactobacillus suspension (5 × 10 7 CFU / mL), and fermented at 33°C and 75% humidity for 10 h to obtain purple highland barley semi-solid fermentation slurry.

[0100] (3) placing all the purple highland barley semi-solid fermentation slurry obtained in step (2), 3 kg of wheat flour, 0.5 kg of gluten, 1.0 kg of high-amylose corn starch, and 1.7 kg of deionized water in a strong resonance mixer, setting the vibration frequency to 150 times / min, the speed to 150 r / min, and the amplitude to 5 mm, and finely mixing the dry and wet materials to obtain mixed flour.

[0101] (4) 0.05 kg of curdlan was dissolved in 1.2 kg of deionized water to prepare a curdlan suspension, which was then poured into a dough mixer with mixed flour to knead the dough (120 r / min, 10 min) to obtain dough.

[0102] (5) The dough was placed in a constant temperature and humidity chamber for proofing for 1 hour (temperature 30°C, humidity 75%), and then composite rolled twice at 2.0, 1.6, 1.2, and 0.9 mm spacings, and single pressed once, and finally cut into strips with a 3 mm square knife. The noodles were placed in an intelligent stage dehydrator for dehydration under the following conditions: first stage: temperature 30°C, humidity 78%, cycle frequency 35 Hz, duration 40 min; second stage: temperature 40°C, humidity 75%, cycle frequency 35 Hz, duration 50 min; third stage: temperature 45°C, humidity 65%, cycle frequency 35 Hz, duration 100 min; fourth stage: temperature 25°C, humidity 60%, cycle frequency 35 Hz, duration 40 min, to obtain purple highland barley noodles.

[0103] Comparative Example 1

[0104] Noodles are prepared using only wheat flour and noodles.

[0105] A method for preparing wheat noodles comprises the following steps:

[0106] (1) Kneading: Weigh 10 kg of wheat flour and 6.4 kg of deionized water, place them in a dough mixer and knead for 8 min to prepare dough.

[0107] (2) Noodle making: After the dough was proofed for 30 min (temperature 30° C., humidity 75%), it was rolled to obtain a dough sheet with a thickness of 1.0 mm, and then cut into strips using a 3 mm square knife and placed in a dehydrator for dehydration (temperature 45° C., humidity 65%, time 100 min).

[0108] Comparative Example 2

[0109] Purple highland barley flour and wheat flour are directly kneaded to prepare noodles.

[0110] A method for preparing purple highland barley noodles comprises the following steps:

[0111] (1) Kneading: Weigh 7 kg of purple barley flour, 3 kg of wheat flour, 0.45 kg of gluten powder, and 6.4 kg of deionized water, and place them in a dough mixer and knead for 8 minutes to prepare dough.

[0112] (2) Noodle making: After the dough was proofed for 30 min (temperature 30° C., humidity 75%), it was rolled to obtain a dough sheet with a thickness of 1.0 mm, and then cut into strips using a 3 mm square knife and placed in a dehydrator for dehydration (temperature 45° C., humidity 65%, time 100 min).

[0113] Comparative Example 3:

[0114] On the basis of comparative example 2, purple highland barley whole flour and purple highland barley bran were compounded and then directly kneaded to prepare noodles.

[0115] A method for preparing purple highland barley noodles comprises the following steps:

[0116] (1) Kneading: Weigh 6.86 kg of purple barley whole flour, 0.14 kg of purple barley bran powder, 3 kg of wheat flour, 0.45 kg of gluten powder, and 6.4 kg of deionized water, and place them in a dough mixer and knead for 8 minutes to prepare dough.

[0117] (2) Noodle making: After the dough was proofed for 30 min (temperature 30° C., humidity 75%), it was rolled to obtain a dough sheet with a thickness of 1.0 mm, and then cut into strips using a 3 mm square knife and placed in a dehydrator for dehydration (temperature 45° C., humidity 65%, time 100 min).

[0118] Comparative Example 4:

[0119] Based on Comparative Example 3, high amylose corn starch was further added, and then the noodles were directly kneaded.

[0120] A method for preparing purple highland barley noodles comprises the following steps:

[0121] (1) 6.86 kg of purple highland barley whole flour, 0.14 kg of purple highland barley bran powder, 3 kg of wheat flour, 0.45 kg of gluten powder, 1.2 kg of high-amylose corn starch, and 5.2 kg of deionized water were placed in a strong resonance mixer, and the vibration frequency was set to 150 times / min, the speed was 150 r / min, and the amplitude was 5 mm. The dry and wet materials were finely mixed to obtain mixed flour.

[0122] (2) 0.05 kg of curdlan was dissolved in 1.2 kg of deionized water to prepare a curdlan suspension, which was then poured into a dough mixer with mixed flour to knead the dough (120 r / min, 10 min) to obtain dough.

[0123] (3) The dough was placed in a constant temperature and humidity chamber for proofing for 1 hour (temperature 30°C, humidity 75%), and then composite rolled twice at 2.0, 1.6, 1.2, and 0.9 mm spacings, and single pressed once, and finally cut into strips with a 3 mm square knife. The noodles were placed in an intelligent stage dehydrator for dehydration under the following conditions: first stage: temperature 30°C, humidity 78%, cycle frequency 35 Hz, duration 40 min; second stage: temperature 40°C, humidity 75%, cycle frequency 35 Hz, duration 50 min; third stage: temperature 45°C, humidity 65%, cycle frequency 35 Hz, duration 100 min; fourth stage: temperature 25°C, humidity 60%, cycle frequency 35 Hz, duration 40 min, to obtain purple highland barley noodles.

[0124] Comparative Example 5

[0125] Lactobacillus plantarum is further added to the formula.

[0126] A method for preparing purple highland barley noodles, compared with Example 4, is different in that no pre-fermentation treatment is performed, but all the ingredients are blended, fermented and kneaded at one time. The method comprises the following steps:

[0127] (1) 6 g of Lactobacillus plantarum (HH-LP56) was sterilized on MRS solid slant medium (0.9 g glucose, 1.3 g agar, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06g MgSO 4 7H 2 O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2 After subculture activation, three loops of cells were inoculated into sterilized MRS liquid medium (0.9 g glucose, 0.7 g yeast extract, 1.3 g broth, 0.2 g NaCl, 0.2 g K 2 HPO 4 、0.06gMgSO 4 7H 2 O, 0.006 g MnSO 4 ·4H 2 O, 0.001 g FeSO 4 7H 2O), cultured in a constant temperature shaking table (35°C, 120r / min) for 2d to prepare a Lactobacillus plantarum activated bacteria seed solution, which was then dispensed into sterile centrifuge tubes, centrifuged at 4°C (10,000r / min, 10min) and the supernatant was discarded, and bacterial mud and sterilized physiological saline (0.9% concentration) were mixed in a 1:1 ratio by oscillation to prepare a Lactobacillus plantarum bacterial suspension.

[0128] (2) 6.86 kg of purple highland barley flour, 0.14 kg of purple highland barley bran powder, 3 kg of wheat flour, 0.45 kg of gluten powder, 1.2 kg of high-amylose corn starch, 10 mL of plant lactobacillus suspension, and 5.2 kg of deionized water were placed in a strong resonance mixer, and the vibration frequency was set to 150 times / min, the speed was 150 r / min, and the amplitude was 5 mm. The dry and wet materials were finely mixed to obtain mixed flour.

[0129] (3) 0.05 kg of curdlan was dissolved in 1.2 kg of deionized water to prepare a curdlan suspension, which was then poured into a dough mixer with mixed flour to knead the dough (120 r / min, 10 min) to obtain dough.

[0130] (4) The dough was placed in a constant temperature and humidity chamber for proofing for 1 hour (temperature 30°C, humidity 75%), and then composite rolled twice at 2.0, 1.6, 1.2, and 0.9 mm spacings, and single pressed once, and finally cut into strips with a 3 mm square knife. The noodles were placed in an intelligent stage dehydrator for dehydration under the following conditions: first stage: temperature 30°C, humidity 78%, cycle frequency 35 Hz, duration 40 min; second stage: temperature 40°C, humidity 75%, cycle frequency 35 Hz, duration 50 min; third stage: temperature 45°C, humidity 65%, cycle frequency 35 Hz, duration 100 min; fourth stage: temperature 25°C, humidity 60%, cycle frequency 35 Hz, duration 40 min, to obtain purple highland barley noodles.

[0131] Performance Testing

[0132] The cooking, texture, sensory properties and in vitro digestion properties of the purple highland barley noodles prepared in the above comparative examples and embodiments were measured, and the specific methods and results are as follows:

[0133] 1. Determination of the optimal cooking time: Take about 15g of highland barley noodles and place them in 500mL of boiling deionized water. After cooking for a certain period of time, take out a certain amount of noodles every 10 seconds or so. The time when the hard core in the center of the noodle cross section disappears is recorded as the optimal cooking time of the highland barley noodles.

[0134] 2. Determination of texture quality: The texture quality of noodles was determined by using a texture analyzer with a P36R probe. The test parameters were as follows: pre-test speed 1.0 mm / s, test speed 1.0 mm / s, post-test speed 1.0 mm / s, and the degree of noodle extrusion deformation during the test was 75%. All tests were completed within 3 minutes after the optimal cooking time of the noodles, and each sample was repeated at least 9 times in parallel.

[0135] 3. Determination of sensory quality: Before the sensory evaluation, all highland barley noodles were cooked for the optimal steaming time and randomly numbered to ensure the objectivity of the test results. The sensory evaluation team consisted of 10 professionals aged between 20 and 30 who had received relevant training. All sensory evaluations were completed within 3 minutes after the noodles were cooked for the optimal steaming time.

[0136] 4. Determination of polyphenol content: Weigh 0.5g of freeze-dried powder of purple highland barley noodles into a 15mL brown centrifuge tube, then add 5mL of methanol (methanol: water = 70:30). Place the centrifuge tube in a water bath at 30°C and 200r / min for 1h, then centrifuge and collect the supernatant. Under the same conditions, extract the precipitate repeatedly according to the above operation, combine the two extracts, and dilute to 10mL with methanol. Take 1mL of the extract in a 10mL centrifuge tube, add 5mL of Folin phenol reagent and mix well, and react in the dark for 7min. Then add 4mL of 7.5% sodium carbonate solution and react at 25°C for 1h in the dark. Finally, measure the absorbance of the reaction solution at 760nm, and indicate the phenol content based on the standard curve made with different concentration gradients of gallic acid.

[0137] 5. Determination of starch gelatinization rate: The composite purple highland barley powder after solid-state fermentation was freeze-dried and ground through an 80-mesh sieve. Subsequently, 70 g of freeze-dried composite black highland barley powder, 30 g of flour and 8 g of gluten powder were fully mixed to obtain mixed flour. According to the method in AACC 54-60, the thermomechanical properties of the mixed flour were measured using a Mixolab device according to the Chopin+ protocol. The gelatinization rate of starch was characterized by the slope (β) of the Mixolab curve in the heating stage between C2 and C3.

[0138] 6. Determination of in vitro digestion and GI value of purple barley noodles: The cooked purple barley noodles were cut into pieces with a length of about 2 mm. 1.0 g of noodle pieces were weighed into a centrifuge tube for subsequent enzymatic hydrolysis steps: First, 5 mL of peptic protein solution (2,500 U / mL, dissolved in 0.01 M hydrochloric acid solution) was added, and the centrifuge tube was placed in a constant temperature shaking water bath incubator (37°C, 220 r / min) for 2 h to simulate the human gastric digestion stage. Then, the simulation experiment of the small intestinal digestion stage was started. After adding 5mL of 0.01mol / L NaOH solution, 15mL of 0.1mol / L phosphate buffer solution (pH 6.8), and 5mL of pancreatic enzyme solution (600U / mL) to the centrifuge tube, the centrifuge tube was placed in a constant temperature shaking water bath incubator (37°C, 220r / min) for incubation. At 0, 10, 20, 30, 60, 90, 120, 150, 180, 240, and 300min, 0.1mL of solution was taken from the centrifuge tube and placed in a 1.5mL centrifuge tube containing 0.3mL of anhydrous ethanol. After centrifugation (10,000g, 10min), 0.1mL of the supernatant was mixed with 0.5mL of amyloglucosidase solution (100U / mL) and reacted at 37°C for 1h. Finally, the glucose content in the reaction solution was determined using a glucose kit. The in vitro hydrolysis rate, hydrolysis kinetics of starch and the estimated Glycemic Index (eGI) of highland barley noodles were calculated according to formulas (1) to (3):

[0139]

[0140] C t =C ∞ ×(1-e -kt ) Formula (2)

[0141] eGI=0.862×HI+8.198 Formula (3)

[0142] 7. Laser confocal microscopy observation of the microstructure of purple highland barley noodles: The cooked noodles were cut into slices with a thickness of 25 μm using a freezing microtome and carefully attached to a glass slide. In order to observe the microstructure of dietary fiber in highland barley noodles, the slices of highland barley noodles were stained with fluorescent white M2R (0.01%, w / v) dye solution, placed under a laser confocal microscope, and a magnification of 20 times was selected to take photos of the stained slices for observation.

[0143] 8. Scanning electron microscopy observation of starch granules in purple highland barley noodles: Weigh 10g of purple highland barley noodle powder, place it in a small beaker, and mix it thoroughly with 60mL of deionized water. Place the above small beaker at room temperature for 1h and stir occasionally. Subsequently, the suspension in the small beaker is centrifuged at 5,000g for 10min, and the supernatant and the yellow substance on the upper layer of the white precipitate are discarded. Repeat the above centrifugation operation twice to remove the yellow substance on the upper layer of the white precipitate after centrifugation to the greatest extent. Next, the obtained white precipitate is dispersed in 40mL of deionized water and sieved through a 200-mesh sieve. Centrifuge the filtrate after sieving and collect the lower precipitate, which is starch. Finally, wash the obtained lower precipitate twice with 70% ethanol and dehydrate it with anhydrous ethanol. After the treated sample is placed in a fume hood to dry naturally, it is placed in a sealed bag for use. During the test, a certain amount of starch sample was sprinkled on the conductive glue, and after gold spraying, the microstructure of the starch granules was observed using a scanning electron microscope. The acceleration voltage used in the imaging process was 5.0 kV.

[0144] The cooking, texture, sensory quality and eGI values ​​of the purple highland barley noodles obtained in Comparative Examples 1 to 4 and Examples 1 to 5 are shown in Table 1.

[0145] Table 1 Comparison of cooking, texture, sensory quality and eGI value of purple highland barley noodles prepared in comparative example and example

[0146]

[0147]

[0148] The free phenol content, TTA and pH value of the purple highland barley noodles obtained in Comparative Examples 4 to 5 and Examples 1 to 5 are shown in Table 2-3.

[0149] Table 2 Comparison of free phenol content in purple highland barley noodles prepared in comparative example and example

[0150]

[0151] Table 3 Comparison of TTA and pH value in purple highland barley noodles prepared in comparative examples and examples

[0152] sample Comparative Example 4 Comparative Example 5 Example 1 Example 2 Example 3 Example 4 Example 5 pH 6.05 6.09 5.97 5.95 5.44 5.05 4.88 TTA 2.00 2.01 2.05 2.12 2.70 3.05 3.27

[0153] As shown in Table 1, the noodles made of wheat flour in Comparative Example 1 have good sensory quality, but have the disadvantage of too high GI value. Comparative Examples 2-3 show that the addition of purple barley flour can significantly reduce the GI value, but still cannot reach the level of low GI value, and the cooking time and hardness are significantly increased, which reduces the quality of noodles; the addition of purple barley flour and barley bran powder can make the GI value of barley noodles close to 55, but its quality deteriorates significantly (cooking time, hardness increase, sensory score decreases); the addition of purple barley flour, barley bran powder and high-amylose corn starch can reduce the GI value of barley noodles to below 55, but the quality of noodles deteriorates most significantly.

[0154] In order to better understand the beneficial effects of the substantial inventions proposed by the present invention, as shown in Table 1, by comparing Examples 1 to 5 with Comparative Examples 2 to 4, it can be seen that semi-solid fermentation of the compound purple highland barley flour can significantly reduce the GI value of highland barley noodles to below 55 (GI=44-53), the optimal cooking time is significantly shortened by 5.0% to 33.9%, the sensory quality is significantly improved by 7.2% to 48.8%, the hardness value is significantly reduced by 9.3% to 36.3%, and the elasticity is significantly improved by 11.3% to 35.2%. This is mainly due to: 1) Semi-solid fermentation can effectively degrade the fiber structure in purple highland barley bran, weakening the hardening effect of the fiber structure on the taste of highland barley noodles. Figure 1 As shown, compared with Examples 1 to 5, in Comparative Example 4, as the fermentation time increases, the bulky dietary fiber structure is gradually destroyed and degraded into smaller fiber fragments. The longer the fermentation time, the greater the degree of fiber degradation, which not only reduces the particle size of the dietary fiber, but also weakens its ability to compete with protein for water absorption, promotes a better formation of the protein network, reduces the hardness value of highland barley noodles, and improves the elasticity and sensory quality of the noodles.

[0155] While degrading purple highland barley bran, semi-solid fermentation can release dietary polyphenols that were originally bound in the fiber structure, converting a large amount of bound polyphenols into free polyphenols, significantly increasing the free phenol content in highland barley noodles. The longer the fermentation time, the more free phenols are released (as shown in Table 2). Free polyphenols can act on the active sites of α-amylase, causing the enzyme activity to decrease, the rate and degree of starch hydrolysis to decrease, and the GI value of noodles to decrease. Figure 2 The fluorescence spectrum shown in the figure shows that the fluorescence intensity of α-amylase gradually weakened with the extension of semi-solid fermentation time, which confirms that the activity of α-amylase continued to decrease, which would inhibit the hydrolysis rate and degree of starch and lead to a decrease in the GI value of noodles, as shown in Table 1.

[0156] During the semi-solid fermentation process, plant lactobacillus will metabolize and produce a certain amount of organic acids, enzymes, extracellular polysaccharides and other substances, especially organic acids, which is also the main reason for the degradation of dietary fiber. As shown in Table 3, compared with Comparative Example 4 (unfermented), the noodles prepared in Examples 1-5 have significantly increased TTA (total titratable acid) and significantly reduced pH values, and the longer the fermentation time, the more acidic substances accumulate, but after more than 8 hours, the growth rate slows down. Solid-state fermentation not only degrades highland barley bran, but also destroys starch granules. Figure 3 As shown in the figure, compared with comparative example 4 (unfermented), the surface of starch granules in the example is gradually eroded and damaged by the increase of organic acid content during the fermentation process, and holes and cracks appear. The appearance of these holes and cracks provides a channel for the entry of water during the cooking process of highland barley noodles, accelerates the diffusion of water into the starch granules and the heat transfer efficiency, and thus improves the gelatinization rate of starch. Figure 4 As shown in Table 1. The increase in starch gelatinization rate will significantly shorten the cooking time required for the cooking of highland barley noodles, and as the fermentation time increases, the cooking time of highland barley noodles becomes shorter and shorter, as shown in Table 1. However, when the fermentation time reaches 10 hours, the effect of improving the taste and elasticity of highland barley noodles will be affected to a certain extent, because excessive fermentation will cause highland barley noodles to accumulate excessive organic acids, which will cause the taste of noodles to be sour. Therefore, the control of the degree of fermentation in the present invention is crucial for reducing the GI value of highland barley noodles and improving the quality.

[0157] In addition, it can be seen from the comparative example 5 and the embodiment that the timing of adding plant lactobacillus for fermentation is very important. For example, the one-time mixed addition in comparative example 5 did not significantly increase the content of free phenols and organic acids compared with the unfermented comparative example 4; while in the embodiment of the present invention, the composite highland barley flour was subjected to semi-solid fermentation treatment in advance, and then noodles were prepared, and this process can significantly increase the content of free phenols and organic acids.

[0158] Example 6

[0159] Referring to Example 4, only the liquid culture medium culture time in step (1) was adjusted, that is, the concentration of the bacterial suspension was different, and the other conditions remained unchanged to obtain the corresponding purple barley noodles.

[0160] The results are shown in the following table:

[0161]

[0162] After a lot of preliminary exploratory experiments, the applicant found that the concentration of the plant lactobacillus suspension inoculated during the semi-solid fermentation process has a great influence on the quality of purple highland barley noodles. Specifically, when the same liquid culture medium is used to culture plant lactobacillus, the culture time is too short (0.5d), which will lead to a too low concentration of plant lactobacillus suspension (1.1×104 CFU / mL, which is much lower than the bacterial suspension concentration obtained after 2 days of fermentation in Example 4 (5.7×10 7 CFU / mL), and the purple highland barley noodles prepared by the same semi-solid fermentation treatment after inoculation, compared with Example 4, have a lower free phenol content and less organic acid accumulation in the noodles, resulting in a harder taste and poor elasticity of the noodles, which are not accepted by consumers; and when Lactobacillus plantarum is cultured in the same liquid medium, the culture time is too long (7d), which will lead to an excessively high concentration of Lactobacillus plantarum suspension (8.5×10 13 CFU / mL, which is much higher than the bacterial suspension concentration obtained after 2 days of fermentation in Example 4 (5.7×10 7 CFU / mL), and after inoculation and use, the purple highland barley noodles were subjected to the same semi-solid fermentation treatment. Compared with Example 4, the free phenol content of the prepared purple highland barley noodles was much increased, but the organic acid accumulated too much in the noodles, resulting in a serious sour taste of the noodles, softening, poor elasticity, breaking when bitten, and not accepted by consumers. The most important thing is that the excessive accumulation of acidic substances will destroy the network structure of the noodles, exposing a large amount of starch, which is very easy to be digested by amylase, thereby increasing its GI value (GI=56.87), and it is no longer a low GI noodle. In short, the semi-solid fermentation technology proposed by the present invention, the preparation of the bacterial suspension involved and the selection of its concentration are optimized through a large amount of experimental work and have strong creativity.

[0163] Example 7

[0164] Referring to Example 4, only the mixing ratio of the purple highland barley bran powder and the purple highland barley whole powder in step (2) is adjusted (the total amount of the two remains unchanged), and the other factors remain unchanged to obtain the corresponding purple highland barley noodles.

[0165] The results are shown in the following table:

[0166]

[0167] The applicant has found through a large number of groping experiments in the early stage that the mixing ratio of purple highland barley bran powder and purple highland barley powder in the semi-solid fermentation process has a great impact on the quality of purple highland barley noodles. Specifically, under the premise that the parameters of semi-solid fermentation are all consistent, when the mixing ratio of highland barley bran powder and purple highland barley powder is too large, although the purple highland barley noodles prepared can reach the standard (GI=50.13) of low GI noodles, and the free phenol content is higher than that of Example 4, but due to the excessive proportion of purple highland barley bran, organic acid accumulation is less, resulting in noodle hardness is very large, elasticity and mouthfeel are poor, and the needs of consumers cannot be met; and when the mixing ratio of highland barley bran powder and purple highland barley powder is too small, compared with Example 4, although the hardness value of the purple highland barley noodles prepared is not high, it can not reach the standard (GI=57.17) of low GI noodles, and the free phenol content is relatively low, the elasticity of noodles is insufficient, and the overall mouthfeel is general, which cannot be accepted by consumers. Even when all highland barley flour is fermented, the GI value of the prepared noodles is as high as 65.12, which is already a medium GI value food, far away from the core purpose of the present invention. In short, the semi-solid fermentation technology proposed by the present invention and the selection of the ratio of purple highland barley bran powder and purple highland barley flour involved are optimized through a large amount of experimental work and have strong creativity.

[0168] Example 8

[0169] Referring to Example 4, only the semi-solid fermentation time in step (2) was adjusted, and the other conditions remained unchanged to obtain the corresponding purple highland barley noodles.

[0170] The results are shown in the following table:

[0171]

[0172] The applicant has found through a large number of exploratory experiments in the early stage that the fermentation time length of the semi-solid fermentation slurry of purple highland barley in the semi-solid fermentation process has a great influence on the quality of purple highland barley noodles. Specifically, under the premise that the parameters of semi-solid fermentation are all consistent, when the fermentation time is too short, although the prepared purple highland barley noodles can reach the standard of low GI noodles (GI=54.02), compared with Example 4, due to insufficient fermentation time, less organic acid accumulation, and low free phenol content, the noodles have a large hardness, poor elasticity and mouthfeel, and cannot meet the needs of consumers; and when the fermentation time is too long, compared with Example 4, although the free phenol content in the prepared purple highland barley noodles is higher, the noodles cannot reach the standard of low GI noodles (GI=57.17). This is mainly due to excessive fermentation, a large amount of organic acid accumulation, which seriously damages the protein network structure inside the noodles, making the skeleton support capacity of the noodles weaker, on the one hand, making the starch exposed more thoroughly, more easily digested and decomposed by amylase, on the other hand, making the noodles hardness value too small, the noodles are not elastic enough, chewy, not chewy, and the overall mouthfeel is poor. At the same time, a large amount of acid makes the pH value of the noodles too low, and the noodles taste too sour, which is not acceptable to consumers. In short, the semi-solid fermentation technology proposed by the present invention and the selection of the semi-solid fermentation time involved are optimized through a large amount of experimental work and have strong creativity.

[0173] The above preferred embodiments are only for explaining the technical concept and working principle of the present invention, and the implementation mode and protection scope of the present invention shall not be limited by the above implementation modes. Any changes, simplifications, combinations, modifications and substitutions made by those skilled in the art without departing from the spirit and principle of the present invention shall be within the protection scope of the claims attached to the present invention.

Claims

1. A low GI noodle, characterized in that: The formula includes the following components: composite purple barley flour, wheat flour, gluten powder, high-amylose corn starch, curdlan, plant lactobacillus, and water; Wherein, the mass ratio of the composite purple barley flour to the wheat flour is (5-7): (1.5-3); The composite purple barley flour is composed of purple barley whole flour and purple barley bran flour, and the mass ratio of the two is (6-49):1; The dosage of Lactobacillus plantarum is 1×10 7 -10×10 7 CFU / kg compound purple barley powder.

2. The low GI noodles according to claim 1, characterized in that The gluten powder accounts for 4wt%-10wt% of the total amount of the composite purple barley flour and wheat flour.

3. The low GI noodles according to claim 1, characterized in that The high-amylose corn starch accounts for 1wt%-15wt% of the total amount of the composite purple barley flour and wheat flour.

4. The low GI noodles according to claim 1, characterized in that The curdlan accounts for 0.2wt%-1wt% of the total amount of the composite purple highland barley flour and wheat flour.

5. The low GI noodles according to claim 1, characterized in that The dosage of the plant lactobacillus is 7-8×10 7 CFU / kg compound purple barley powder.

6. The low GI noodles according to claim 1, characterized in that The water content in the total amount of the compounded purple barley flour and wheat flour is 50%-70%.

7. A method for preparing the low GI noodles according to any one of claims 1 to 6, comprising the following steps: (1) According to the formula described in any one of claims 1 to 6, the composite purple highland barley powder is first mixed with a portion of water, and then inoculated with a plant lactobacillus suspension, mixed and semi-solid fermented to obtain a purple highland barley paste; (2) according to the formula of any one of claims 1 to 6, wheat flour, gluten, high amylose corn starch, and a portion of water are mixed with the obtained purple highland barley flour to obtain mixed flour flocs; (3) According to the formula of any one of claims 1 to 6, curdlan is mixed with the remaining water to prepare a curdlan suspension, and then mixed with the mixed flour to prepare dough; (4) allowing the dough to rise in a constant temperature and humidity environment, and then rolling and cutting into strips to form noodles; and then dehydrating the noodles to obtain purple highland barley noodles.

8. The preparation method according to claim 7, characterized in that: In step (1), the concentration of the Lactobacillus plantarum suspension is 1×10 7 -10×10 7 CFU / mL; the mass fraction of water to the composite purple highland barley powder is 50% to 60%.

9. The preparation method according to claim 7, characterized in that: In step (1), the semi-solid fermentation conditions are 30° C. to 37° C., 70% to 80% humidity, and 2-12 hours.

10. The preparation method according to claim 7, characterized in that: In step (2), the mixing is carried out in a strong resonance mixer, with the vibration frequency set at 150 to 300 times / min, the rotation speed set at 150 to 200 r / min, and the amplitude set at 5 to 10 mm; In step (3), the dough is kneaded at 120-200 r / min for 10-15 min; In step (4), the proofing conditions are: temperature 25°C to 35°C, humidity 70% to 80%, and time 1 to 4 hours; the dehydration treatment includes the following processes: the first stage: temperature 30°C, humidity 75% to 85%, cycle frequency 35 Hz, and duration 20 to 40 minutes; The second stage: temperature 40℃, humidity 70%~80%, cycle frequency 35Hz, duration 30~50min; the third stage: temperature 45℃, humidity 60%~70%, cycle frequency 35Hz, duration 80~120min; the fourth stage: temperature 25℃, humidity 55%~65%, cycle frequency 35Hz, duration 20~40min.

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