JP2012185038A - Prediction method for starch damage degree of rice powder and evaluation method for processing suitability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and prompt prediction method for a starch damage degree of rice powder and to evaluate processing suitability of the rice powder by predicting the starch damage degree of the rice powder.SOLUTION: A prediction method for a starch degree of rice powder includes a first step of bringing rice powder in contact with water, letting the rice powder absorb water and measuring a change in a moisture content of the rice powder with respect to the lapse of time after contact, and a second step of determining water absorption coefficients (a), K, (n) and (b) by substituting the lapse of time after contact and the moisture content of the rice powder into an approximate expression (I): Y(t)=a[1-exp(-K×t)]+b, in which (t) is time.

Description

  The present invention relates to a method for predicting starch damage of rice flour and a method for evaluating processability.

  Rice flour has been used in traditional rice crackers such as dumplings, rice cakes, and rice crackers, but in recent years, from the viewpoint of improving food self-sufficiency, consumption has been promoted by developing new uses for rice flour.

  Conventional rice flour has different flour characteristics depending on the production method, and there are various types of rice flour such as upper fresh powder and fallen rice flour depending on the purpose. In recent years, as a new application, attempts have been made to use rice flour for bread, confectionery, noodles and the like. However, conventional rice flour has a problem in that it cannot produce good quality bread because its particle size is too large. Therefore, the milling method has been improved, and it has become possible to make the particle size of rice flour smaller than before.

  However, when the particle size is reduced, starch contained in the rice is damaged by frictional heat and physical impact caused by pulverization, and rice flour having a high degree of starch damage is easily prepared. It is said that the starch damage degree of rice flour is particularly concerned with bread-making suitability, and starch damage degree is an important factor as a characteristic of rice flour (Non-patent Document 1).

  Currently, as a method for measuring the degree of starch damage, there is an enzyme method (AACC method 76-31) for measuring the degree of starch damage using α-amylase and amyloglucosidase. This enzyme method is used as a method for evaluating the starch damage degree of wheat flour, but is also applied to rice flour. Although this method is quantitative, the operation is complicated and the results are likely to vary because the enzyme reaction is sensitive to temperature and time. Therefore, skilled operations are required to obtain reproducible results. In addition, a spectrophotometer is required to measure absorbance.

  Patent Document 1 discloses a method of measuring the amount of oxygen consumed during enzyme treatment with a dissolved oxygen electrode as a method for quickly and easily measuring the degree of starch damage. In this method, the measurement time of the oxygen consumption is set to 3 minutes, but the time required for the enzyme treatment is not included in the measurement time and actually requires several hours of measurement. Therefore, although it is simple, it cannot be said to be a rapid measurement.

  Non-Patent Document 2 discloses an enzyme method (BAP method) for measuring the degree of starch damage using β-amylase and pullulanase as a method for measuring the gelatinization degree of starch. Since the starch damage degree and the gelatinization degree are closely related, it is possible to predict the starch damage degree from the gelatinization degree. However, the BAP method, like the measuring method disclosed in Patent Document 1, is quantitative but requires complicated operations.

  Non-Patent Document 3 discloses a turbidity method for evaluating the transparency of a starch solution. The turbidity method has the advantage of being simple and accurate to some extent. However, this method is not widely known, and there are few application examples with rice flour.

  In addition, there are methods for measuring the degree of starch damage by X-ray diffraction, thermal analysis using a differential scanning calorimeter, and the like. Moreover, the examination using FT-IR is performed as a method of estimating the gelatinization degree at the time of rice cooking of a rice grain (nonpatent literature 4). These methods each have a problem that they are not suitable for general use because they require expensive devices for measurement.

JP-A-8-242891

Kouichi Scorpio, Junko Matsuki, Hiroshi Okadome, Kyoko Okabe, Keitaro Suzuki, Tomoya Okuni, Yoshiaki Kitamura, Akira Hori, Junyo Yamada, Shio Matsukura, “The Institute of Food Research [Technical Report]”, 2010, Vol. 74, p. 37-44 Shinji Kakinuma, Atsuko Matsunaga, Masahide Edagawa, Shoichi Kobayashi, “Starch Science”, 1981, Vol. 28, No. 4, p. 235-240 Shoko Shibukawa, Hiroho Fukuba, “Home Economics Magazine”, 1973, Vol. 24, No. 1, p. 45-48 Sonoko Ayabe, Kyoko Tanaka, Yoko Hamada, Midori Kasai, Keiko Hatae, “The Journal of Japan Society for Food Science and Technology”, 2006, 53, 9, p. 481-488

  The object of the present invention is to provide a simple and quick method for predicting the degree of starch damage in rice flour. Moreover, it aims at evaluating the processability of rice flour by predicting the starch damage degree of rice flour.

ADVANTAGE OF THE INVENTION According to this invention, the prediction method of the starch damage degree of rice flour is provided. The method comprises a first step of bringing rice flour into contact with water so that the rice flour absorbs water, and measuring a change in the moisture content of the rice flour with respect to the elapsed time after contact; the elapsed time after the contact and the moisture content of the rice flour; A second step of fitting the rate to the following approximate expression (I) to obtain the water absorption coefficients a, K, n, and b. T in the formula (I) is time.
Y (t) = a [1-exp (−K × t ⁿ )] + b (I)

  ADVANTAGE OF THE INVENTION According to this invention, the prediction method of the starch damage degree of the rice flour simple and quick can be provided. Furthermore, the processability of rice flour, such as the ability to make bread and the confectionery, can be evaluated, and the rice flour suitable for the application can be selected.

It is a figure which shows the one aspect | mode of the measuring method of a moisture content. It is a graph which shows the particle size distribution of the rice flour in Example 1. It is a graph which shows the change of the moisture content of the rice flour in Example 1. It is a graph which shows the correlation of the water absorption coefficient K in Example 1, and a starch damage degree. It is a graph which shows the correlation of the water absorption coefficient K / a in Example 1, and a starch damage degree. It is a graph which shows the correlation of the water absorption coefficient K in Example 1, and the specific volume of bread. It is a graph which shows the correlation of the water absorption coefficient K / a in Example 1, and the specific volume of bread. It is a graph which shows the correlation of the water absorption coefficient K in Example 2, and a starch damage degree. It is a graph which shows the correlation of the water absorption coefficient K / a in Example 2, and a starch damage degree.

  In one embodiment of the present invention, a method for predicting the starch damage degree of rice flour using the novel approximate formula (I) is provided. In this method, the time change of the moisture content of rice flour is measured, and the measurement result is applied to the approximate expression (I) to obtain the water absorption coefficient of the approximate expression (I). Here, the degree of starch damage refers to the ratio of the mass of damaged starch to the total mass of starch contained in rice flour.

Hereinafter, the method for predicting the starch damage degree of rice flour in this embodiment will be described in detail.
First, in the first step, the rice flour is brought into contact with water so that the rice flour absorbs water. The mass of the rice flour that has absorbed water is measured, and the moisture content of the rice flour is calculated. The mass is measured, for example, at regular intervals after the rice flour is brought into contact with water, and the change in the moisture content of the rice flour with respect to the elapsed time after the contact is measured.

Here, the moisture content of rice flour refers to the ratio of the amount of water contained in rice flour to the mass of rice flour before the start of measurement (initial rice flour mass). The amount of water contained in the rice flour is the sum of the moisture contained in the rice flour before the start of measurement (initial moisture content) and the moisture absorbed in the rice flour during the measurement. That is,
Water content of rice flour = initial water content + water absorption / initial rice powder mass.

  In addition, the mass (dry mass) of the rice flour before the start of measurement and the moisture or moisture content (initial moisture content or initial moisture content) contained in the rice flour are measured in advance.

Next, in the second step, the measured moisture content of the rice flour and the elapsed time after contact are applied to the following approximate expression (I) to obtain the water absorption coefficients a, K, n, and b. In the formula (I), t is time.
Y (t) = a [1-exp (−K × t ⁿ )] + b (I)
Approximation formula (I) having these four kinds of water absorption coefficients has a high correlation with the starch damage degree of rice flour, and is a novel expression found by the present inventors through earnest research.

  In the approximate expression (I), the water absorption coefficient a reflects the ratio of the amount of water to the initial rice flour mass, that is, the saturated water absorption rate when the rice flour absorbs water after the measurement is started and the water is saturated. The water absorption coefficient b reflects the initial moisture content. The value obtained by adding the water absorption coefficients a and b reflects the saturated water content.

  The water absorption coefficient K reflects the water absorption speed. The larger the value of the water absorption coefficient K, the faster the water absorption rate of rice flour and the shorter the time to reach the saturated water content. On the other hand, the smaller the value of the water absorption coefficient K, the slower the water absorption speed of the rice flour and the longer it takes to reach the saturated moisture content.

  The water absorption coefficient n reflects the change in the water absorption speed. The larger the value of the water absorption coefficient n, the sharper the change in the initial water absorption rate of the rice flour. The smaller the value of the water absorption coefficient n, the slower the change in the water absorption rate of the rice flour.

  The present inventors have revealed that the water absorption coefficient K and the water absorption coefficient K / a in the approximate formula (I) have a high inverse correlation with the starch damage degree. It has been demonstrated that the water absorption coefficient K and the water absorption coefficient K / a have a high inverse correlation with the starch damage degree by measuring the starch damage degree of rice flour by an enzymatic method and comparing it with the result. Therefore, the starch damage degree of rice flour can be predicted based on the value of the water absorption coefficient K or K / a.

  The greater the water absorption coefficient K or K / a, the lower the starch damage degree, and the smaller the water absorption coefficient K or K / a, the higher the starch damage degree. Either the water absorption coefficient K or K / a may be used for the prediction of the starch damage degree, but K / a is more preferable. Normally, the greater the starch damage, the greater the amount of moisture absorbed, but since a is a water absorption coefficient reflecting the saturated water absorption, the water absorption coefficient K / a is considered to have a higher correlation with the starch damage degree.

  Moreover, by including the water absorption coefficient n in the approximate expression (I), it is possible to reflect the water absorption patterns of all kinds of rice flour. Therefore, the method for predicting the degree of starch damage according to this embodiment is any water absorption, for example, rice flour that has a large initial water absorption change but hardly absorbs water thereafter, and rice flour that has a water absorption pattern that gradually absorbs water like wheat flour. It can also be applied to rice flour having a pattern.

  In addition, the process of calculating | requiring the water absorption coefficient a, K, n, and b by applying the measured moisture content of rice flour and the elapsed time after contact to approximate expression (I) can be performed by general spreadsheet software. For example, an actual measurement value is input to Microsoft Excel, and the coefficient of the approximate expression can be obtained by repeated calculation using a solver function.

  The measurement in the first step is not limited to this, but can be performed by placing a filter paper inside a container having an opening at the bottom, placing rice flour on it, and allowing the bottom of the container to stand in water. it can.

  One mode of measuring the moisture content will be described with reference to FIG. First, the filter paper 2 is laid on the cylindrical measurement container 1, and the rice flour 3 whose initial moisture content is measured in advance is placed thereon, and the mass of the container is measured. This is the initial mass. An opening 5 is provided in advance in the bottom 4 of the measurement container 1.

  Next, the measurement container 1 is placed in a shallow water tank 6 so that the bottom 4 of the measurement container 1 is left in water. As a result, water enters the measuring container 1 through the opening 5 in the bottom 4, comes into contact with the rice flour 3, and the rice flour 3 absorbs water. After the measurement is started, for example, the mass of the measurement container is measured at regular intervals.

  As the measurement container 1, a container formed of a material that does not absorb water is used. For example, an aluminum can can be used, but is not limited thereto. The container shape is not limited to a cylindrical shape as long as it has a bottom and can be filled with rice flour inside, and may be any shape.

  An opening 5 is provided in the bottom 4 of the measurement container 1 so that water can enter. Although the magnitude | size of the opening 5 is not specifically limited, For example, a diameter can be 1-4 mm. It is preferable that the number of the apertures 5 be a sufficient number so that the apertures 5 are evenly arranged in the bottom 4 of the container and water smoothly enters the measurement container 1.

  Although the water depth in the water tank 6 should just be lower than the height of the measurement container 1, since the water penetration to the rice flour 3 will become quick if the water depth is too deep, the shallower one is preferable. If the water depth is in the range of 5 to 20 mm, more accurate measurement is possible. Moreover, it is preferable that the amount of water put in the water tank 6 is an amount sufficiently larger than the maximum absorption amount of the rice flour 3.

  The measurement is preferably performed after bringing the rice flour into contact with water until the moisture content of the rice flour is saturated, for example, it is preferably performed for about 30 minutes to 1 hour.

  The rice flour used in the method for predicting the degree of starch damage in this embodiment may be, for example, polished rice, brown rice and germinated brown rice flour, and various rice flours such as birch and red rice bran, and is a polished rice flour. It is more preferable.

  As described above, according to this aspect, by using the approximate expression (I), the starch damage degree of rice flour can be measured easily, quickly, and inexpensively.

  In a further aspect of the present invention, there is provided a method for evaluating the processing aptitude of rice flour such as breadmaking aptitude and confectionery aptitude based on the water absorption coefficient of the approximate formula (I). Here, the rice flour having high processability refers to rice flour having a high water absorbency of dough and rice flour having high expansibility during fermentation and baking.

  The present inventors have clarified that the water absorption coefficient K and the water absorption coefficient K / a in the above approximate formula (I) have a correlation with workability. Therefore, the processability of rice flour can be evaluated based on the value of the water absorption coefficient K or K / a. For example, rice flour having a large water absorption coefficient K or K / a has high processability, and bread produced using such rice flour has a large specific volume. On the other hand, rice flour having a small water absorption coefficient K or K / a has low processability, and bread produced using such rice flour has a small specific volume.

  Moreover, based on the value of the water absorption coefficient K or K / a, rice flour suitable for processing can be selected. For example, in order to produce bread or confectionery that requires good foamability, rice flour having a large water absorption coefficient K or K / a may be selected.

  Furthermore, based on the value of the water absorption coefficient K or K / a, it is possible to predict an appropriate amount of water absorption when preparing the dough using rice flour. Thereby, it is also possible to improve the swelling at the time of fermentation or baking of bread or confectionery.

(Measurement of moisture content)
Using rice flour of samples 1 to 5 having different average particle diameters, the change in moisture content with time was measured. An aluminum can having a diameter of about 40 mm was used as a measurement container. Seven holes with a diameter of about 2 mm were provided at equal intervals on the bottom of the aluminum can. After placing circular glass filter paper having the same diameter on the bottom of the measurement container, the mass of the measurement container was measured.

  Next, 5 g of rice flour whose moisture content was measured in advance was placed on the filter paper and spread evenly on the bottom of the container. The mass was then measured (initial mass).

  The measurement container was left still on a bat filled with water having a depth of 10 mm. The time when allowed to stand was defined as a measurement time of 0 minutes. The measurement container was taken out at regular intervals, wiped with a cloth, measured for mass, and placed on the bat again. This operation was repeated for about 30 minutes until there was no change in mass.

  The obtained water content change with time was applied to the approximate expression (I) to obtain the water absorption coefficients a, K, n, and b.

(Measurement of starch damage by enzymatic method)
About the rice flour of samples 1-5, the starch damage degree was measured by the enzyme method. A rice powder sample (50 mg) and an α-amylase solution (100 μl) were added to a 15 ml sample tube, stirred with a vortex mixer, and subjected to an enzyme reaction in a warm bath at 40 ° C. for 10 minutes. Thereafter, 4 ml of 0.2% v / v dilute sulfuric acid was added to stop the enzyme reaction, followed by centrifugation (2,000 g, 5 minutes), and then the supernatant was collected. 100 μl of the supernatant and 100 μl of the amyloglucosidase solution were added to a 10 ml glass test tube, stirred for 5 seconds with a vortex mixer, and subjected to an enzyme reaction in a warm bath at 40 ° C. for 10 minutes. Thereafter, 4 ml of a glucose coloring solution was added and reacted in a warm bath at 40 ° C. for 20 minutes, and then the absorbance at 510 nm was measured with a spectrophotometer.

  A calibration curve was prepared by adding 100 μl of a 1.5 mg / ml glucose solution, 100 μl of acetate buffer and 4 ml of a glucose coloring solution to a glass test tube, and determining the absorbance at 510 nm after 20 minutes. Based on this calibration curve, the starch damage degree of the rice flour of Samples 1 to 5 was calculated.

(Measure the viscosity of bread dough)
Bread dough was prepared using the rice flour of Samples 1 to 5, and its viscosity was measured. A dough was prepared by kneading 192 g of a rice flour sample, 48 g of gluten, and 216 g of water (90% based on the flour). About each dough produced using the rice flour of Samples 1 to 5, the resistance (Nm) to the mechanical shearing force was measured under the conditions of a temperature of 30 ° C. and a rotational speed of 63 rpm. The viscosity of the dough was expressed by the Brabender unit (BU), which is a unit widely used as a comparative reference value in measuring the viscosity of flour.

(Preparation of bread)
Bread was prepared using the rice flour of Samples 1-5. The composition of the materials was as follows.

240g rice flour sample
60g gluten
234g of water
5g salt
Super white sugar 15g
Skim milk 6g
Shortening 15g
5g dry yeast
Rice flour and gluten were mixed, and salt, super white sugar, skim milk, shortening, dry yeast and water were added and mixed to prepare a dough. The prepared dough was put in a mold and fermented in an environment of 40 ° C. and 80% humidity for 50 minutes. Then, it baked for 30 minutes in 180 degreeC oven. After allowing to cool overnight at room temperature, the height, mass, and specific volume were measured. The specific volume was measured by the rapeseed method.

(Measurement result)
Table 1 shows the water absorption coefficients a, K, n, and b of the rice flour samples 1 to 5, initial moisture content (%), average particle diameter (μm), starch damage degree (%) measured by the enzyme method, and dough viscosity. (BU), bread height (cm), bread mass (g), bread bread specific volume (ml / g). The average particle size was measured using a general particle size distribution measuring machine.

  From Table 1, it can be seen that the higher the degree of starch damage, the higher the dough viscosity tends to be and the lower the bread breadth and specific volume. Thus, the starch damage degree shows a high correlation with the dough viscosity, bread height and specific volume, and it can be seen that it is a factor affecting bread making aptitude.

  In FIG. 2, the graph of the particle size distribution of the rice flour of the samples 1-5 was shown. Sample 1 has a wide particle size distribution and contains a large amount of rice flour with a small particle size. Therefore, it is predicted that the degree of starch damage is large. On the other hand, Sample 5 had the narrowest particle size distribution.

  In FIG. 3, the time change of the moisture content of the rice flour of samples 1-5 was shown. Sample 1 had a slow change in water absorption rate, and it took a long time until the water content was saturated. On the other hand, Sample 5 had a sharp change in water absorption rate, and the time until the water content was saturated was short. From this, it is considered that the wider the particle size distribution, the slower the change in the water absorption rate and the longer the time until the water content is saturated.

  4 and 5 show the relationship between the water absorption coefficients K and K / a of the rice flours of Samples 1 to 5 and the degree of starch damage. As shown in the figure, it can be seen that the water absorption coefficients K and K / a in the approximate expression have a high inverse correlation with the starch damage degree. Therefore, it was shown that the starch damage degree can be estimated from the water absorption coefficient K or K / a.

  6 and 7 show the relationship between the water absorption coefficients K and K / a of the rice flours of Samples 1 to 5 and the specific volume of bread. As shown in the figure, it can be seen that the water absorption coefficients K and K / a of the approximate expression have a high correlation with the specific volume of bread. Therefore, it was shown that the bread-making ability of rice flour can be evaluated from the water absorption coefficient K or K / a.

  Using commercially available rice flour, the water absorption coefficient of the approximate formula (I) was determined, and the correlation with the degree of starch damage was examined. Samples 6 to 10 are obtained by classifying commercially available rice flour obtained by dry-grinding a dip into five fractions. Samples 11 to 15 are obtained by classifying commercially available rice flour obtained by wet-grinding the dip into five fractions. Samples 16, 17, 18, and 19 are commercially available rice flour made from Sasanishiki, Akitakomachi, domestic rice, and Hitomebore, respectively.

  About each of the samples 6-19, the moisture content was measured as described in Example 1, and the water absorption coefficients a, K, n, and b of the approximate formula (I) were obtained. Further, as described in Example 1, the degree of starch damage was measured by an enzymatic method.

Table 2 shows the water absorption coefficient a, K, n, b, average particle diameter (pm), and starch damage degree (%). 8 and 9 show the relationship between the water absorption coefficients K and K / a and the degree of starch damage.

  8 and 9, it can be seen that the water absorption coefficients K and K / a have a high inverse correlation with the starch damage degree, respectively. Therefore, it was shown that the starch damage degree can be estimated from the water absorption coefficient K or K / a.

  According to the present invention, the starch damage degree of rice flour can be predicted easily and quickly. Moreover, by predicting the starch damage degree of rice flour, it is possible to evaluate the suitability of rice flour for baking and confectionery, and it is possible to select an appropriate rice flour according to the purpose.

  DESCRIPTION OF SYMBOLS 1 ... Measuring container, 2 ... Filter paper, 3 ... Rice flour sample, 4 ... Bottom part of measuring container, 5 ... Open hole, 6 ... Water tank.

Claims (6)

A first step of bringing the rice flour into contact with water and absorbing the water into the rice flour, and measuring a change in the moisture content of the rice flour with respect to the elapsed time after the contact;
Applying the elapsed time after the contact and the moisture content of the rice flour to the following approximate formula (I) to obtain a water absorption coefficient a, K, n, b;
Method for predicting starch damage of rice flour, including:
Y (t) = a [1-exp (−K × t ⁿ )] + b (I)
In the formula, t is time.   The prediction method according to claim 1, wherein the starch damage degree of rice flour is predicted based on at least one value of the water absorption coefficient K and K / a.   In the first step, the measurement is performed by laying filter paper inside a container having an opening at the bottom, placing rice flour thereon, and allowing the bottom of the container to stand in water, The prediction method according to claim 1 or 2.   The prediction method according to claim 1, wherein the rice flour is milled rice flour.   In order to evaluate the processability of rice flour, the water absorption coefficient of the approximate formula (I) obtained according to claim 1 is used.   The evaluation method according to claim 5, wherein the processability of rice flour is evaluated based on at least one value of the water absorption coefficient K and K / a.

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