A method for preparing black rice vermicelli with reduced loss of anthocyanins

Abstract

The present invention discloses a method for preparing black rice vermicelli that reduces the loss of anthocyanins, thereby solving the problem of large-scale loss of beneficial anthocyanin bioactive substances during the preparation process and further processing and consumption of black rice vermicelli. On the one hand, the method moderately whitens black rice to separate the black rice husk from the white rice, and then crushes and extracts the black rice husk before using it to prepare rice vermicelli, thereby reducing the loss of anthocyanin bioactive substances during the preparation process. On the other hand, during the preparation process, the method first extracts the anthocyanin bioactive substances from the black rice husk powder using an extractant, then adsorbs them with popcorn powder, and uses mung bean starch as an embedding material, so that the anthocyanin bioactive substances are embedded during the processing of the black rice vermicelli. This reduces the dissolution rate of the anthocyanin bioactive substances in the black rice vermicelli product during hot water cooking, significantly reducing the loss of anthocyanin bioactive substances during the processing and consumption of the black rice vermicelli.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and particularly relates to a method for preparing black rice vermicelli capable of reducing the loss of anthocyanins. Background Art

[0002] Black rice, also known as purple rice or purple-black rice, is known as the "black pearl" or "tribute rice." Compared to regular rice, black rice boasts significant development and utilization potential due to its richer content of anthocyanins, a bioactive substance found in its hull. These compounds offer antioxidant, anti-aging, lipid-lowering, anti-inflammatory, anti-atherosclerotic, and diabetes- and related metabolic disease-modifying properties.

[0003] Rice vermicelli, a popular staple food that first gained popularity in southern my country, has now spread across Southeast Asia, Europe, and the United States, where Chinese communities gather, attracting a large consumer base. Processing black rice into black rice vermicelli not only caters to the dietary habits of rice noodle consumers but also offers a variety of nutritional and health benefits, making it a more popular option than regular rice vermicelli. The market prospects are promising.

[0004] At present, the commonly used preparation process of rice vermicelli includes the following steps: rice → light grinding to remove impurities → washing → soaking → water and rice separation → adding water to grind → dehydration → stirring ingredients → initial steaming → extruding into sheets → extruding into threads → forming.

[0005] However, if the above process is used to prepare black rice vermicelli, the following problems may occur:

[0006] First, during the preparation process, a large amount of anthocyanin bioactive substances in black rice will be lost. This is because the anthocyanin bioactive substances in the black rice skin are water-soluble substances. During the soaking, immersion and grinding steps of the black rice vermicelli processing, a large amount of anthocyanin bioactive substances will be dissolved in water and lost, resulting in a significant reduction in the content of anthocyanin bioactive substances in the prepared black rice vermicelli, which greatly weakens the nutritional and health functions of the product.

[0007] Secondly, when black rice vermicelli is processed and eaten by cooking in hot water, the anthocyanin bioactive substances in it will dissolve in the soup and cause them to be lost again; in addition, the color of the black rice vermicelli will become lighter and lighter, resulting in poor product color.

[0008] Therefore, when developing new technologies and methods for preparing black rice vermicelli, minimizing the loss of biological activity of black rice anthocyanins during preparation and processing is the key to the black rice vermicelli preparation process. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for preparing black rice vermicelli with reduced loss of anthocyanins, thereby solving the problem of large-scale loss of beneficial anthocyanins bioactive substances during the preparation process and further processing and consumption of black rice vermicelli.

[0010] The present invention is achieved through the following technical solutions:

[0011] A method for preparing black rice vermicelli with reduced anthocyanin loss comprises the following steps:

[0012] (1) crushing popcorn and sieving to obtain popcorn powder;

[0013] (2) grinding the black rice to whiten it, and collecting the black rice husk and white rice after grinding;

[0014] (3) soaking the white rice obtained in step (2) in water and draining the water, then grinding the rice with water and then dehydrating the rice to obtain wet white rice powder;

[0015] (4) crushing the black rice skin obtained in step (2) and sieving to obtain black rice skin powder;

[0016] (5) adding an extractant to the black rice bran powder, stirring and extracting, and then filtering to obtain anthocyanin extract and black rice bran residue;

[0017] (6) mixing the anthocyanin extract with the popcorn powder to allow the popcorn powder to fully adsorb the anthocyanin, thereby obtaining a popcorn powder-extract mixture;

[0018] (7) adding mung bean starch to the mixture obtained in step (6) to encapsulate the popcorn powder adsorbed with anthocyanins, and stirring evenly to obtain a mixed slurry encapsulating the popcorn powder;

[0019] (8) uniformly mixing the mixed slurry obtained in step (7) with the white rice wet powder and the black rice peel residue, and adjusting the moisture to obtain a black rice vermicelli base;

[0020] Then, the black rice vermicelli base material is added into a preheated rice noodle machine, the rice vermicelli is squeezed out, and the rice vermicelli is cut according to a set length to obtain a black rice vermicelli product.

[0021] The popcorn described in the present invention refers to a puffed food obtained by processing rice through a popcorn machine, and does not contain other raw materials such as oil or sugar.

[0022] On the one hand, the present invention utilizes the characteristic that anthocyanin bioactive substances are mainly distributed in the rice husk of black rice. By moderately whitening the black rice, the black rice husk is separated from the white rice, and the black rice husk is crushed and extracted before being used to prepare rice vermicelli. The soaking, refining and dehydration processes are avoided, and the loss of anthocyanin bioactive substances during the preparation process of black rice vermicelli is reduced.

[0023] On the other hand, in the preparation process of black rice vermicelli, the present invention uses an extractant to first extract the anthocyanin bioactive substances in the black rice hull powder, and then uses popcorn powder to adsorb them. Mung bean starch is further used as an embedding material to embed the popcorn powder adsorbed with the anthocyanin bioactive substances, thereby reducing the dissolution rate of the anthocyanin bioactive substances in the black rice vermicelli product during hot water cooking and significantly reducing the loss of the anthocyanin bioactive substances when the black rice vermicelli is processed and eaten.

[0024] Preferably, in step (1), the popcorn is crushed and then passed through a sieve of 80-100 meshes.

[0025] Preferably, in step (2), the whitening rate of black rice is 8-12%.

[0026] Preferably, in step (3), the white rice is soaked in water for 2 to 4 hours and then drained.

[0027] Preferably, in step (4), the black rice husks are crushed and then passed through an 80-100 mesh sieve.

[0028] Preferably, the extractant in step (5) is composed of the following components in mass percentage: 55% ethanol, 41% water, and 4% lactic acid; the mass ratio of the extractant to black rice bran powder is 3 to 5:1.

[0029] Preferably, in step (5), after adding the extractant to the black rice bran powder, the mixture is stirred and extracted for 1 to 23 hours.

[0030] Preferably, in step (6), the mass ratio of the anthocyanin extract to the popcorn powder is 4 to 8:1, and the two are mixed and stirred for 60 to 80 minutes.

[0031] Preferably, in step (7), the mass of mung bean starch added is 12-18% of the mass of the anthocyanin extract.

[0032] Preferably, in step (8), the moisture content of the black rice vermicelli base material is 36-44%.

[0033] Preferably, in step (8), the rice noodle machine is preheated to 90-100°C.

[0034] Compared with the prior art, the present invention solves the problem of large-scale loss of anthocyanin bioactive substances in black rice during the preparation process of black rice vermicelli, thereby ensuring the nutritional value of the black rice vermicelli product. On the other hand, it solves the problem of loss of anthocyanin bioactive substances in black rice vermicelli during processing by hot water cooking, as well as the problem of lighter color and poor color of the product caused by this. DETAILED DESCRIPTION

[0035] The following examples are only used to illustrate the present invention, and the scope of protection of the present invention is not limited to the following examples. Those skilled in the art can achieve the purpose of the present invention based on the above disclosure of the present invention and the ranges of various parameters.

[0036] The black rice, popcorn and mung bean starch used in the following examples are all commercially available products.

[0037] Comparative Example 1 Existing method for preparing rice vermicelli (preparing black rice vermicelli without popcorn adsorption or mung bean starch embedding)

[0038] (1) soaking black rice in water for 3 hours and then draining, adding water to the black rice and dehydrating the black rice to obtain black rice wet powder;

[0039] (2) black rice wet powder is regulated to 40% moisture to obtain the black rice vermicelli base;

[0040] (3) preheating a rice noodle machine to 90° C., adding black rice vermicelli base thereto, squeezing out rice vermicelli, and cutting the vermicelli into 28 cm lengths to obtain the product.

[0041] Comparative Example 2: Preparation of black rice vermicelli using only mung bean powder for embedding without using popcorn for adsorption

[0042] (1) crushing popcorn and passing it through an 80-mesh sieve to obtain popcorn powder;

[0043] (2) whitening the black rice (whitening rate 8%), and collecting the white rice and black rice husks after whitening;

[0044] (3) soaking the white rice obtained in step (2) in water for 3 hours and then draining the water, then adding water to grind the rice and dehydrate it to obtain wet white rice powder;

[0045] (4) crushing the black rice skin obtained in step (2) and passing it through a 100-mesh sieve to obtain black rice skin powder;

[0046] (5) adding an extractant (ethanol: water: lactic acid = 55 wt%: 41 wt%: 4 wt%) to the black rice husk powder at a mass ratio of extractant: black rice husk powder = 3:1, stirring and extracting for 2 hours, and filtering to obtain anthocyanin extract and black rice husk residue, respectively;

[0047] (6) adding 18 wt% mung bean starch to the anthocyanin extract and stirring uniformly to obtain a mixed slurry containing anthocyanins;

[0048] (7) uniformly mixing the mixed slurry obtained in step (6), the white rice wet powder obtained in step (3), and the black rice skin residue obtained in step (5), and adjusting the moisture content to 36% to obtain a black rice vermicelli base;

[0049] Preheat the rice noodle machine to 90° C., then add the black rice vermicelli base material thereto, extrude the rice vermicelli, and cut it into 28 cm lengths to obtain the product.

[0050] Comparative Example 3: No mung bean starch was used for embedding, only popcorn was used for adsorption to prepare black rice vermicelli.

[0051] (1) crushing popcorn and passing it through an 80-mesh sieve to obtain popcorn powder;

[0052] (2) whitening the black rice (whitening rate 8%), and collecting the white rice and black rice husks after whitening;

[0053] (3) soaking the white rice obtained in step (2) in water for 3 hours and then draining the water, then adding water to grind the rice and dehydrate it to obtain wet white rice powder;

[0054] (4) crushing the black rice skin obtained in step (2) and passing it through a 100-mesh sieve to obtain black rice skin powder;

[0055] (5) adding an extractant (ethanol: water: lactic acid = 55 wt%: 41 wt%: 4 wt%) to the black rice husk powder at a mass ratio of extractant: black rice husk powder = 3:1, stirring and extracting for 2 hours, and filtering to obtain anthocyanin extract and black rice husk residue, respectively;

[0056] (6) mixing the anthocyanin extract obtained in step (5) with popcorn powder in a mass ratio of anthocyanin extract to popcorn powder of 6:1, and stirring for 80 minutes to allow the popcorn powder to fully absorb the anthocyanin, thereby obtaining a popcorn powder-extract mixture;

[0057] (7) uniformly mixing the mixture obtained in step (6), the white rice wet powder obtained in step (3), and the black rice husk residue obtained in step (5), and adjusting the moisture content to 36% to obtain a black rice vermicelli base;

[0058] Preheat the rice noodle machine to 90° C., then add the black rice vermicelli base material thereto, extrude the rice vermicelli, and cut it into 28 cm lengths to obtain the product.

[0059] Comparative Example 4: Black rice bran powder was not subjected to extraction, adsorption and embedding treatment, but was directly mixed with white rice wet powder to prepare black rice vermicelli.

[0060] (1) crushing popcorn and passing it through an 80-mesh sieve to obtain popcorn powder;

[0061] (2) whitening the black rice (whitening rate 8%), and collecting the white rice and black rice husks after whitening;

[0062] (3) soaking the white rice obtained in step (2) in water for 3 hours and then draining the water, then adding water to grind the rice and dehydrate it to obtain wet white rice powder;

[0063] (4) crushing the black rice skin obtained in step (2) and passing it through a 100-mesh sieve to obtain black rice skin powder;

[0064] (5) mixing the white rice wet powder and the black rice bran powder, and adjusting the moisture content to 36% to obtain the black rice vermicelli base;

[0065] Preheat the rice noodle machine to 90° C., then add the black rice vermicelli base material thereto, extrude the rice vermicelli, and cut it into 28 cm lengths to obtain the product.

[0066] Example 1

[0067] (1) crushing popcorn and passing it through an 80-mesh sieve to obtain popcorn powder;

[0068] (2) whitening the black rice (whitening rate 8%), and collecting the white rice and black rice husks after whitening;

[0069] (3) soaking the white rice obtained in step (2) in water for 3 hours and then draining the water, then adding water to grind the rice and dehydrate it to obtain wet white rice powder;

[0070] (4) crushing the black rice skin obtained in step (2) and passing it through a 100-mesh sieve to obtain black rice skin powder;

[0071] (5) adding an extractant (ethanol: water: lactic acid = 55 wt%: 41 wt%: 4 wt%) to the black rice husk powder at a mass ratio of extractant: black rice husk powder = 3:1, stirring and extracting for 2 hours, and filtering to obtain anthocyanin extract and black rice husk residue, respectively;

[0072] (6) mixing the anthocyanin extract obtained in step (5) with popcorn powder in a mass ratio of anthocyanin extract to popcorn powder of 6:1, and stirring for 80 minutes to allow the popcorn powder to fully absorb the anthocyanin, thereby obtaining a popcorn powder-extract mixture;

[0073] (7) adding 18 wt % mung bean starch to the mixture obtained in step (6), stirring evenly to obtain a mixed slurry containing popcorn powder;

[0074] (8) uniformly mixing the mixed slurry obtained in step (7), the white rice wet powder obtained in step (3), and the black rice skin residue obtained in step (5), and adjusting the moisture content to 36% to obtain a black rice vermicelli base;

[0075] Preheat the rice noodle machine to 90° C., then add the black rice vermicelli base material thereto, extrude the rice vermicelli, and cut it into 28 cm lengths to obtain the product.

[0076] Example 2

[0077] (1) crushing popcorn and passing it through an 80-mesh sieve to obtain popcorn powder;

[0078] (2) whitening the black rice (whitening rate 8%), and collecting the white rice and black rice husks after whitening;

[0079] (3) soaking the white rice obtained in step (2) in water for 3 hours and then draining the water, then adding water to grind the rice and dehydrate it to obtain wet white rice powder;

[0080] (4) crushing the black rice skin obtained in step (2) and passing it through a 100-mesh sieve to obtain black rice skin powder;

[0081] (5) adding an extractant (ethanol: water: lactic acid = 55 wt%: 41 wt%: 4 wt%) to the black rice husk powder at a mass ratio of extractant: black rice husk powder = 3:1, stirring and extracting for 2 hours, and filtering to obtain anthocyanin extract and black rice husk residue, respectively;

[0082] (6) mixing the anthocyanin extract obtained in step (5) with popcorn powder in a mass ratio of anthocyanin extract to popcorn powder of 6:1, and stirring for 80 minutes to allow the popcorn powder to fully absorb the anthocyanin, thereby obtaining a popcorn powder-extract mixture;

[0083] (7) adding 18 wt % mung bean starch to the mixture obtained in step (6), stirring evenly to obtain a mixed slurry containing popcorn powder;

[0084] (8) uniformly mixing the mixed slurry obtained in step (7), the white rice wet powder obtained in step (3), and the black rice skin residue obtained in step (5), and adjusting the moisture content to 36% to obtain a black rice vermicelli base;

[0085] Preheat the rice noodle machine to 90° C., then add the black rice vermicelli base material thereto, extrude the rice vermicelli, and cut it into 28 cm lengths to obtain the product.

[0086] Example 3

[0087] (1) crushing popcorn and passing it through a 90-mesh sieve to obtain popcorn powder;

[0088] (2) whitening the black rice (whitening rate 12%), and collecting the white rice and black rice husks after whitening;

[0089] (3) soaking the white rice obtained in step (2) in water for 4 hours and then draining the water, then adding water to grind the rice and dehydrate it to obtain wet white rice powder;

[0090] (4) crushing the black rice skin obtained in step (2) and passing it through a 100-mesh sieve to obtain black rice skin powder;

[0091] (5) adding an extractant (ethanol: water: lactic acid = 55 wt%: 41 wt%: 4 wt%) to the black rice husk powder at a mass ratio of extractant: black rice husk powder = 4:1, stirring and extracting for 1 hour, and filtering to obtain anthocyanin extract and black rice husk residue, respectively;

[0092] (6) mixing the anthocyanin extract obtained in step (5) with popcorn powder in a mass ratio of anthocyanin extract to popcorn powder = 4:1, and stirring for 70 minutes to allow the popcorn powder to fully absorb the anthocyanin substances, thereby obtaining a popcorn powder-extract mixture;

[0093] (7) adding 14 wt % mung bean starch to the mixture obtained in step (6), stirring evenly to obtain a mixed slurry containing popcorn powder;

[0094] (8) uniformly mixing the mixed slurry obtained in step (7), the white rice wet powder prepared in step (3), and the black rice husk residue obtained in step (5), and adjusting the moisture content to 40% to obtain a black rice vermicelli base;

[0095] Preheat the rice noodle machine to 100° C., then add the black rice vermicelli base material thereto, extrude the rice vermicelli, and cut it into 28 cm lengths to obtain the product.

[0096] Example 4

[0097] (1) Grinding popcorn and passing it through a 100-mesh sieve to obtain popcorn powder;

[0098] (2) whitening the black rice (whitening rate 10%), and collecting the white rice and black rice husks after whitening;

[0099] (3) soaking the white rice obtained in step (2) in water for 2 hours and then draining the water, then adding water to grind the rice and dehydrate it to obtain wet white rice powder;

[0100] (4) crushing the black rice skin obtained in step (2) and passing it through a 90-mesh sieve to obtain black rice skin powder;

[0101] (5) adding an extractant (ethanol: water: lactic acid = 55 wt%: 41 wt%: 4 wt%) to the black rice husk powder at a mass ratio of extractant: black rice husk powder = 5:1, stirring and extracting for 3 hours, and filtering to obtain anthocyanin extract and black rice husk residue, respectively;

[0102] (6) mixing the anthocyanin extract obtained in step (5) with popcorn powder in a mass ratio of anthocyanin extract to popcorn powder of 8:1, and stirring for 60 minutes to allow the popcorn powder to fully absorb the anthocyanin, thereby obtaining a popcorn powder-extract mixture;

[0103] (7) adding 12 wt % mung bean starch to the mixture obtained in step (6), stirring evenly to obtain a mixed slurry containing popcorn powder;

[0104] (8) uniformly mixing the mixed slurry obtained in step (7), the white rice wet powder prepared in step (3), and the black rice husk residue obtained in step (5), and adjusting the moisture content to 44% to obtain a black rice vermicelli base;

[0105] Preheat the rice noodle machine to 95° C., then add the black rice vermicelli base material thereto, extrude the rice vermicelli, and cut it into 28 cm lengths to obtain the product.

[0106] Example 5

[0107] (1) crushing popcorn and passing it through an 80-mesh sieve to obtain popcorn powder;

[0108] (2) whitening the black rice (whitening rate 10%), and collecting the white rice and black rice husks after whitening;

[0109] (3) soaking the white rice obtained in step 2) in water for 3 hours and then draining the water, then grinding with water and dehydrating to obtain wet white rice powder;

[0110] (4) crushing the black rice skin obtained in step (2) and passing it through an 80-mesh sieve to obtain black rice skin powder;

[0111] (5) adding an extractant (ethanol: water: lactic acid = 55 wt%: 41 wt%: 4 wt%) to the black rice husk powder at a mass ratio of extractant: black rice husk powder = 3:1, stirring and extracting for 4 hours, and filtering to obtain anthocyanin extract and black rice husk residue, respectively;

[0112] (6) mixing the anthocyanin extract obtained in step (5) with popcorn powder in a mass ratio of anthocyanin extract to popcorn powder of 6:1, and stirring for 70 minutes to allow the popcorn powder to fully absorb the anthocyanin, thereby obtaining a popcorn powder-extract mixture;

[0113] (7) adding 18 wt % mung bean starch to the mixture obtained in step (6), stirring evenly to obtain a mixed slurry containing popcorn powder;

[0114] (8) uniformly mixing the mixed slurry obtained in step (7), the white rice wet powder prepared in step (3), and the black rice skin residue obtained in (5), and adjusting the moisture content to 44% to obtain a black rice vermicelli base;

[0115] Preheat the rice noodle machine to 90° C., then add the black rice vermicelli base material thereto, extrude the rice vermicelli, and cut it into 28 cm lengths to obtain the product.

[0116] Example 6

[0117] (1) crushing popcorn and passing it through a 90-mesh sieve to obtain popcorn powder;

[0118] (2) whitening the black rice (whitening rate 8%), and collecting the white rice and black rice husks after whitening;

[0119] (3) soaking the white rice obtained in step (2) in water for 2 hours and then draining the water, then adding water to grind the rice and dehydrate it to obtain wet white rice powder;

[0120] (4) crushing the black rice skin obtained in step (2) and passing it through a 100-mesh sieve to obtain black rice skin powder;

[0121] (5) adding an extractant (ethanol: water: lactic acid = 55 wt%: 41 wt%: 4 wt%) to the black rice husk powder at a mass ratio of extractant: black rice husk powder = 4:1, stirring and extracting for 2 hours, and filtering to obtain anthocyanin extract and black rice husk residue, respectively;

[0122] (6) mixing the anthocyanin extract obtained in step (5) with popcorn powder in a mass ratio of anthocyanin extract to popcorn powder of 8:1, and stirring for 70 minutes to allow the popcorn powder to fully absorb the anthocyanin, thereby obtaining a popcorn powder-extract mixture;

[0123] (7) adding 12 wt % mung bean starch to the mixture obtained in step (6), stirring evenly to obtain a mixed slurry containing popcorn powder;

[0124] (8) uniformly mixing the mixed slurry obtained in step (7), the white rice wet powder prepared in step (3), and the black rice skin residue obtained in step (5), and adjusting the moisture content to 36% to obtain a black rice vermicelli base;

[0125] Preheat the rice noodle machine to 95° C., then add the black rice vermicelli base material thereto, extrude the rice vermicelli, and cut it into 28 cm lengths to obtain the product.

[0126] Test example

[0127] ① The anthocyanin content in the black rice vermicelli prepared in the above embodiment and comparative example was measured. The results are shown in Table 1.

[0128] ② The black rice vermicelli prepared in the above embodiment and comparative example was processed by hot water cooking for consumption, and the anthocyanin content in the processed black rice vermicelli and the soup was measured. The results are shown in Table 1.

[0129] The specific operation for determining the anthocyanin content in the processed black rice vermicelli and soup is as follows:

[0130] (1) Take appropriate amount of black rice vermicelli and measure its moisture content;

[0131] (2) Accurately weigh 200 g of black rice vermicelli with known moisture content in (1) for later use;

[0132] (3) Accurately weigh 1000 g of drinking water and place it in a pot, bring to a boil, add the black rice vermicelli into the pot, and keep it at a slight boil for 5 min;

[0133] (4) Take 5 mL of the cooked soup and 5 g of black rice vermicelli respectively and measure the anthocyanin content;

[0134] (5) taking an appropriate amount of the cooked black rice vermicelli prepared in step (3) and measuring the moisture content;

[0135] (6) Calculate and determine the content of anthocyanins in the black rice vermicelli and soup after cooking based on the measurement results (the content of anthocyanins in the black rice vermicelli after cooking is converted into the water content of the black rice vermicelli before cooking).

[0136] Among them, the determination method of anthocyanin content in this test example is:

[0137] Take 5g of black rice vermicelli or 5mL of black rice vermicelli soup and place them in a 50mL centrifuge tube, add 10mL Acidified ethanol (ethanol: 1 mol / L HCl = 85:15, V / V), homogenized in an ice bath for 5 min (10000 r / min), centrifuged at 10000 r / min for 5 min, collected the supernatant, and added 10 mL of pre-cooled The acidified ethanol solution was extracted once again according to the above conditions, and the two supernatants were combined and stored at -20°C for later use.

[0138] Anthocyanin content was determined using the pH differential method: 1 mL of the test solution was added with 9 mL of pH 1.0 potassium chloride buffer and 9 mL of pH 4.5 sodium acetate buffer, respectively. The solution was allowed to equilibrate for 40 minutes. Distilled water was used as a blank control, and the absorbance was measured at 511 nm and 700 nm using a microplate reader. Total anthocyanin content was calculated as cyanidin-3-O-glucoside.

[0139]

[0140] Where:

[0141] c——anthocyanin content (calculated as cyanidin-3-O-glucoside, mg / g or mg / mL);

[0142] A1 - absorbance at 511 nm of a potassium chloride buffer solution with a pH value of 1.0;

[0143] A2 - absorbance at 700 nm of a pH 1.0 potassium chloride buffer solution;

[0144] A3 - absorbance at 511 nm with sodium acetate buffer at pH 4.5;

[0145] A4 - absorbance at 700 nm with sodium acetate buffer at pH 4.5;

[0146] Mw – molecular weight of cyanidin-3-O-glucoside (449.2 g / mol);

[0147] DF——dilution factor;

[0148] ε——molar extinction coefficient (25,740cm 2 / mol);

[0149] l——Optical path, the path length of the microplate is 0.645cm.

[0150] Table 1

[0151]

[0152] The results in Table 1 above indicate that the method of the present invention can prevent the large-scale loss of anthocyanin bioactive substances during the preparation process of black rice vermicelli, and also solves the problem of large-scale dissolution of anthocyanin bioactive substances during processing, so that the content of anthocyanin bioactive substances remains high when consumed, thereby ensuring the nutritional value of black rice vermicelli.

Claims

1. A method for preparing black rice vermicelli that reduces the loss of anthocyanins, characterized in that: The following steps are involved: (1) Grinding popcorn and sieving to obtain popcorn powder; (2) grinding the black rice to whiten it, and collecting the black rice husk and white rice separately; (3) soaking the white rice obtained in step (2) in water, draining the water, grinding the rice with water, and then dehydrating the rice to obtain wet white rice powder; (4) crushing the black rice skin obtained in step (2) and sieving to obtain black rice skin powder; (5) adding an extractant to the black rice bran powder, stirring and extracting, and then filtering to obtain anthocyanin extract and black rice bran residue, respectively; the extractant is composed of the following components in percentage by weight: 55% ethanol, 41% water, and 4% lactic acid; the mass ratio of the extractant to the black rice bran powder is 3-5:1; (6) mixing the anthocyanin extract with the popcorn powder so that the popcorn powder fully absorbs the anthocyanin, thereby obtaining a popcorn powder-extract mixture; the mass ratio of the anthocyanin extract to the popcorn powder is 4 to 8:1, and the two are mixed and stirred for 60 to 80 minutes; (7) Adding mung bean starch to the mixture obtained in step (6) to encapsulate the popcorn powder adsorbed with anthocyanins, and stirring evenly to obtain a mixed slurry; the mass of the mung bean starch added is 12-18% of the mass of the anthocyanin extract; (8) uniformly mixing the mixed slurry obtained in step (7) with the white rice wet powder and the black rice skin residue, and adjusting the moisture content to obtain a black rice vermicelli base; Then, the black rice vermicelli base material is added into a preheated rice noodle machine, the rice vermicelli is squeezed out, and the rice vermicelli is cut according to a set length to obtain a black rice vermicelli product.

2. The method for preparing black rice vermicelli according to claim 1, wherein The whitening rate of black rice in step (2) is 8-12%.

3. The method for preparing black rice vermicelli according to claim 2, wherein In step (3), soak the white rice in water for 2 to 4 hours and then drain.

4. The method for preparing black rice vermicelli according to claim 3, wherein In step (5), the extractant is added to the black rice bran powder, and the mixture is stirred and extracted for 1 to 23 hours.

5. The method for preparing black rice vermicelli according to claim 4, wherein The moisture content of the black rice vermicelli base in step (8) is 36-44%.

6. The method for preparing black rice vermicelli according to claim 5, wherein The popcorn in step (1) and the black rice skin in step (4) are sieved through an 80-100 mesh sieve after being crushed.

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