I. INTRODUCTION

Many disasters have occurred in recent years. The Japanese government calls on the general public to stockpile food for at least three days.

In addition, in some areas, residents are asked to collect food for a week. In that case, baby food for infants, nursing care food for the elderly, allergy-friendly food, pathological food, and the like are problematic. If lifelines are cut off, and there is no water, gas, electricity, etc., it will be impossible to cook meals. That is where ready-made commercial products come in handy. In particular, white rice porridge, which is allergy-free and contains water, is one of the foods you should always be on hand. We can make baby food by making white rice porridge, a uniform liquid with a mixer. When white rice porridge is processed in a blender, it contains a lot of water, so the viscosity is thin, and there is a risk of aspiration by the elderly. Liquid white rice porridge needs t be thickened with a commercially available thickener so that people with impaired swallowing ability can eat it safely. In this study, we report the results of viscosity measurement by line spread test using commercially available white rice porridge and four types of thickeners.

II. MATERIALS AND METHODS

The nutritional components of the white rice porridge used in this experiment are shown in the Table 1. The white rice porridge used had $33.2\mathrm{kcal}$ and $7.86\mathrm{g}$ of carbohydrates per $100\mathrm{g}$ (displayed on the product packaging).

Table 2 shows the content and nutritional value of the four commercially available thickeners used in this experiment. The main component of all thickeners was dextrin (displayed on the product packaging).

Talbe 2 Content and nutritional value of four types of thickeners

a) Sample (food with Thickener added) adjustment

Samples were adjusted according to previous reports ${}^{1,2,3,4}$. Each of the three foods was prepared as follows.

1. The viscosity of the food product was measured without any modification (homogenize with a mixer) after 30 seconds, 5 minutes, 15 minutes, and 30 minutes.

2. The viscosity of the food product was measured with modification (homogenize with a mixer) after 30seconds, 5minutes, 15minutes, and 30minutes.

3. The viscosity was measured on the food product with modification (homogenize with a mixer) after adding 2grams of thickener (A, B, C, and D) to the food (100g) after 30seconds, 5minutes, 15minutes, and 30minutes.

b) Viscosity measurement method

Using Line Spread Test Start Kit (LST) manufactured by SARAYA, the viscosity of each food was measured. The measurement procedure is as follows. The line spread test (LST) was performed in a room with room temperature of 24 degrees. Viscosity measurements by line spread test (LST) were performed three times using the same sample. Data was obtained by averaging the viscosity results of three repeated measurements. The measurement method was according to Line Spread Test Start Kit (LST) manufactured by SARAYA.

1. Place the sheet on a level surface. Place a ring with an inner diameter of $30\mathrm{mm}$ in the center of the concentric circles.

2. Add the liquid to be measured to the total thickness of therig (20ml) and let stand for 30 seconds.

3. Lift the ring vertically, and after 30 seconds, measure the spread distance of the solution. Six points on the outermost circumference of the sample spread concentrically were measured, and the average value was calculated as the result of LST values.

4. After still standing for 5 minutes, the spread of the samples is measured again at 6 points, and the average value is recorded as the LST value.

c) Criteria for viscosity

There are three levels of classification by LST value⁵⁾. The first stage is mildly thick with a viscosity that falls within the range of 43mm to 36mm (50-150 mPa · s). As for the properties, when the spoon is tilted, it flows down quickly²⁾. The second stage is moderately thick with a viscosity that falls within the range of 36mm to 32mm (150-300 mPa · s). As for the properties, when you tilt the spoon, it flows to the surface²⁾. The third stage is highly thick with a viscosity that falls within the range of 32mm to 30mm (300-500 mPa · s). Even if the spoon is tilted, the shape is maintained to some extent, and does not flow easily⁵⁾.

d) Statistical processing

This study was statistically processed using statistical processing software (Excel 2010: SSRI Co., Ltd). The data to be compared were first tested for normal distribution by F-test. For comparisons between correlated data, the paired Student-t test was used for normally distributed data. Wilcoxon test was used for non-normally distributed data.

III. RESULTS

Table 3 shows the line spread test results. The viscosity of white rice porridge decreased from extremely thick to moderately thick with time. When the white rice porridge was processed with a mixer to become a uniform liquid, the viscosity became mildly thick. And then, the thickener was added to the liquid white rice porridge, the thickness of liquid white rice porridge remained highly dense.

a) Statistical processing results

The line spread test results and statistical processing results are shown in Table 4-9. Except for the white rice porridge with Thickener D, the viscosity was statistically significantly weakened from 30 seconds to 5 minutes. The white rice porridge with Thickener D, the viscosity was statistically significantly weakened from 5 minutes to 15 minutes. However, all the viscosities of the white rice porridge with Thickener fell into the highly thick.

IV. DISCUSSIONS

People with impaired swallowing function are at risk of aspiration form ingesting food mixed with small solids. In the case of white rice porridge, there is a possibility of aspiration depending on the physical condition of the person who eats it because there are rice grains left. If the porridge is made into a uniform liquid using a mixer, the porridge has high water content. It thus becomes less dense, further increasing the possibility of aspiration by the person[6,7]. The safe consumption of liquid porridge requires the addition of thickeners. All four types of thickeners used this time were able to increase the thickness of the porridge that was made into a uniform liquid using a mixer, making into highly thick. The use of thickeners is effective for providing safe meals. To respond to disasters, we think it is realistic to stockpile porridge and Thickener together.

In the future, we would like to conduct similar tests on various types of rice porridge on the market, accumulate the results, and report them.

V. CONCLUSION

An attempt was made to adjust the viscosity for people with impaired swallowing function by using commercially available retort porridge and a commercially available thickening agent, which are also helpful in times of disaster. As a result, when commercially available retort white rice porridge becomes a uniform liquid using a mixer, its viscosity decreases, making it a dangerous ingredient for people with weakened swallowing functions. Therefore, a commercially available thickener was used to adjust the thickness of the liquid porridge. As a result, the liquid porridge became highly dense and stable. We think it is necessary to stockpile thickeners along with rice porridge so that many people can eat it safely even in the event of a disaster.

ACKNOWLEDGMENTS

We would like to thank Ms. Sahoko Ito for her cooperation in the LST experiment.