Development of ready-to-eat (RTE) liwet rice with corn analog rice substitution as an alternative food in emergency conditions

This research aims to develop ready-to-eat (RTE) rice based on local food, namely liwet rice which is substituted with corn analog rice. This RTE rice is intended for food supplies in disaster emergencies and still contributes to the food diversification program. The RTE liwet rice production carried out in this study was by using the retort process. The retort process was carried out using an autoclave at 121 0C for 15 minutes and used retort pouch packaging. The RTE liwet rice in this study made used five formulations of corn analog rice substitution, namely 0%, 20%, 30%, 40%, and 50%. The resulting liwet rice was then analyzed for its physicochemical and organoleptic characteristics. The results showed that the substitution of corn analog rice had a significant effect on the proximate content and physical properties (texture and color) of the liwet rice produced but did not significantly affect the pH and organoleptic characteristics. The best formula in this study was obtained in the 30% substitution of corn analog rice.


Introduction
Indonesia is in the Pacific Ring of Fire and has dozens of active faults. This typographical condition of Indonesia caused Indonesia to have a high level of vulnerability to natural disasters such as earthquakes and volcanic eruptions [1]. One of the problems that often occurred after natural disasters are the disconnection of distribution lines and food supply. This has resulted in disaster-affected communities experiencing difficulties in meeting their food needs. Thus, the existence of emergency food products (EFPs) in the form of ready-to-eat (RTE) foods plays an important role when facility shortages occur during natural disasters. RTE makes it easier to meet one of their basic needs, namely by still paying attention to complete nutrition so that daily energy needs are met [2].
One way that can be used to make RTE food is to use retort processing technology. Retort technology is known as modern sterilization which packs food products in airtight packaging. This retort process technology can be used for various food products. The product will be processed into a retort machine known as an autoclave with high pressure using a sterilization temperature of 121-131 0 C for a certain time. Retort food product packaging is usually in the form of cans, glass bottles, special plastic IOP Publishing doi: 10.1088/1755-1315/1169/1/012099 2 bottles, special glass cups, trays, and pouches made of aluminum and certain plastics that are resistant to high-temperature processing [3]. The application of processing and packaging technology using retort technology is needed so that food products have a longer shelf life without damaging the physical condition and nutrition of the food, and not changing the taste of the food [4].
The development of local food into RTE products can also be done using this retort process technology, one of which is in the process of making RTE liwet rice. This RTE liwet rice product can be used to meet food needs in emergency conditions, especially during disasters. The local flavors that are developed are expected to be more in line with the tastes of the community. However, the declining local food security requires us to innovate to create diversified food products, so it minimalizes depends on one type of commodity, such as rice. Local commodities such as corn can be used as a substitute for rice. One of the processed corn products that have the potential to be developed is corn analog rice. But until now the public's interest in corn analog rice is still quite low. Therefore, to increase food diversification and meet the food needs of the community, especially in disaster conditions, one of the efforts that can be done is to create a new food product that still maintains local flavors, namely RTE liwet rice which is substituted with corn analog rice.
Analog rice is one of the food products made from partially or fully non-rice ingredients, such as corn, cassava, and sorghum. Analog rice is made using extrusion technology so that the resulting product is molded to resemble the shape of rice grains that have undergone gelatinization. Corn analog rice has several advantages over native rice, including high fiber, low glycemic index, contains natural antioxidants, quick cook, no need to be washed before cooking, and give longer full feeling [2]. Therefore, analog rice can be used as a food diversification material so that the food consumption of the Indonesian people become diverse and does not depend on only one type of commodity. According to the description above, the research related to the development of ready-to-eat (RTE) liwet rice formulations with corn analog rice substitutions as alternative food in emergency conditions. So, in this study, the development of a substitute formula for rice analog corn in the manufacture of RTE rice liwet using retort technology. This is intended so that the resulting RTE liwet rice is easy to consume and serve, has good and acceptable physicochemical and organoleptic characteristics, and has a long shelf life.

Materials
This research used IR64 rice varieties obtained from the market, the corn analog rice obtained from the IPB University, salt merk Dolphin (from PT. Susanti Megah in Indonesia), sugar merk Gulaku (from PT. Sugar Group Companies in Indonesia), and dried ingredients such as lime leaves, bay leaves, lemongrass, fried shallots, fried garlic, cayenne pepper, and fried small anchovies. Chemical reagents for analysis such as ethanol, methanol, n-hexane, H2SO4, HCl, etc, were obtained from Merck (PT. Merck Tbk. Merck Groups Companies in Indonesia).

Preparation of RTE liwet rice
The production of liwet rice as carried out using five formulations of corn analog rice substitution with a proportion of 0-50% (0%, 20%, 30%, 40%, 50%). Firstly, 50 gr of white rice and corn analog rice are weighed. Then, the rice is washed once in a bowl and drained the water. Dried ingredients, salt, and sugar were put in a bowl. As much as 50 ml of water is put into the bowl and mixed evenly. The ratio of water to rice is 1:1. After thoroughly mixing, the samples were put into a retort pouch and vacuumsealed packaging. The sample will be retorted at 121 0 C for 15 minutes.

Determination of physical characteristics
The physical characteristics tested on the sample include color and texture. In a color analysis using a colorimetric method that follows the guidelines of a colorimeter (Portable Colorimeter 3nh NH310, China) with the results obtained in the form of CIE L*a*b* [5]. The texture analysis uses the texture IOP Publishing doi:10.1088/1755-1315/1169/1/012099 3 profile analysis (TPA) method with the Shimadzu EZ-SX texture analyzer tool. The texture parameter of the sample analyzed is hardness obtained from the Shimadzu Trapezium X software program [6].

Determination of proximate content
The determination of the proximate content was carried out using the AOAC method [7]. Analysis of water content was carried out using method no. 925.09 (gravimetric), analysis of ash content using a muffle furnace (method No. 923.0), analysis of protein content using the Kjeldahl method (method no. 992.23), analysis of fat content using the Soxhlet method (method no. 920.39C) for cereal fat, and analysis of carbohydrate content using the by difference method, which is the result of a reduction of 100% with water content, ash content, protein content, and fat content.

Determination of pH value
Analysis of pH value was carried out using a benchtop digital pH meter Eutech pH 700 (Cat.EC-PH700/42S) instrument [7]. Firstly, the pH meter will be calibrated by using some buffer solutions such as pH 4, pH 7 and pH 10. Then, 20 ml of sample solution was prepared in the beaker. Lastly, the probe of pH meter was dipped into the beaker to measure the pH value of sample.

Determination of sensory properties
Two tests were carried out in the organoleptic test, namely the hedonic test and the ranking test [8]. This organoleptic test was conducted on 35 untrained panelists. In hedonic testing, the test parameters carried out on samples include color, aroma, taste, texture, and overall.

Data analysis
Data analysis was performed using the instrument or the IBM SPSS Statistics 25 software application for windows. The data obtained will be analyzed using one-way ANOVA. To determine the effect of the formulation on each of the quality characteristics of the product being tested, it will be analyzed using a further test, namely Duncan's test with a 95% confidence level. The ranking test data obtained will be processed using a non-parametric method, namely the Friedman test and continued with the LSD rank further test. In addition, to support the conclusion of the best or selected formulation, the determination of the best formulation is carried out using the exponential comparison method (MPE) [9].

Physical characteristics
Measurement of physical characteristics carried out is color and texture of the resulting RTE liwet rice. Table 1 shows that the greater the substitution of corn analog rice, the lower the texture of the RTE liwet rice produced. The decrease in texture value can be influenced by the starch gelatinization process and the amylose content contained in the rice. The presence of starch granule gelatinization can reduce the hardness, compactness, and elasticity if there is additional time in the process so that it is able to bind hydrogen to the starch granule structure and hydrogen is more denatured [10]. However, in this study, no observations were made on the gelatinization temperature of the liwet rice.
Rice with low amylose content tends to produce rice with a soft texture, while rice with high amylose content tends to produce rice with a dry, non-sticky, and hard texture. IR64 rice has an amylose content of 23,88% categorized as rice with moderate amylose content, of 20-25% [11]. Meanwhile, the amylose content contained in corn flour which is the main ingredient in the manufacture of corn analog rice is 6,25-15,68% [12]. This showed that the amylose content contained in corn analog rice is lower than IR64 rice so with the addition of a higher proportion of corn analog rice, it can produce a softer rice texture.  Table 2 showed the color value of RTE liwet rice. The yellow color produced by the sample comes from the color of corn flour which is the main ingredient of corn analog rice and protein which combines with sugar or starch in a high-temperature state which affects the brightness of the color of the sample. The color changes that occurred in the five sample formulations were influenced by the Maillard reaction. The Maillard reaction is a chemical reaction that occurs due to a reaction between reducing sugars such as glucose and fructose with amino or protein groups to produce amine glucose compounds [10]. In Table 3 below, the protein content decreased along with the addition of corn analog rice. This has an impact on increasing the brightness level (value L*) obtained by the sample. In addition, a change in the intensity of the yellow color (value b*) in the sample was caused using corn analog rice made from yellow corn flour [13]. The yellow color of corn flour is identical to the high content of carotenoids, namely beta carotene [14]. The presence of carotenoid pigments in corn tends to cause the sample to have a reddish color. Thus, an increase in the level of redness (value a*) of the sample was influenced by the presence of carotenoid pigments in yellow corn.

Proximate Content
The proximate content (water content, ash content, protein content, fat content, and carbohydrate content) of ready-to-eat (RTE) liwet rice are presented in Table 3. Based on the data obtained, the increase in substitution of corn analog rice causes the water content in the liwet rice produced to decrease. IR64 rice is known to have an amylose content of 23,88% which is classified as rice with moderate amylose content, namely 0-25% [11]. Meanwhile, the amylose content in corn flour which is the main ingredient in making corn analog rice is 6,25-15,68% [12]. The lower amylose content in corn analog rice is lower than IR64 rice which results in lower water content as the proportion of corn analog rice increases.
The amylose content of IR64 rice and corn analog rice affected the decrease in water content obtained in the five formulations. The low starch content in rice affected the amount of water absorbed by rice during the cooking process. The low amylose content tends to reduce the water content of the product [15]. This can be caused by the amylose chain structure has many hydroxyls groups so that amylose is able to form larger hydrogen bonds and has polar properties [16]. Thus, the higher the amylose content, the higher the water content of the product because the starch's ability to absorb water tends to be large.  The use of corn analog rice in the formulation of RTE liwet rice samples affected the decrease in the ash content value obtained. Corn flour which is known as the main component in the manufacture of corn analog rice has an ash content of 0,67% [12]. The ash content of several local rice varieties ranges from 0,4 to 0,91% [17]. The ash content in corn flour tends to be lower than the ash content of local white rice although the difference between them is not large.
The difference in the proportion of using corn analog rice in the production of RTE liwet rice resulted in a decrease and difference in the protein content obtained. The endosperm (grain) that can be obtained after this milling process is high in carbohydrates and has a protein content of 7% [18]. Based on the research beforehand, the protein content of rice milling degree is 7,4% while the corn analog rice formulation made has a protein content of 6,47-7,26% [12]. The protein content of corn analog rice tends to be lower than the protein content of local rice although the difference between the two is not too big.
The fat content contained in corn analog rice affects the decrease in the fat content value in the five RTE liwet rice formula. Corn analog rice which has the main component of corn flour is known to have 1-2% fat content [12]. Corn flour is known to have a low-fat content, this is because the corn kernel which has a high-fat content is not included in the milling of corn into flour. The endosperm is the part that will be ground into flour, and it is known that this part is high in carbohydrate content [13].
The addition of the proportion of corn analog rice in RTE liwet rice was able to increase the carbohydrate content of liwet rice. It is known that the carbohydrate content in rice milling degree is 89.56% while the corn analog rice formulation made has a carbohydrate content of 90,46-92,01% [12]. Based on the literature, it is known that the carbohydrate content of rice analog corn is higher due to the use of flour as a source of carbohydrates [11]. Corn flour is the main ingredient for making corn analog rice, and analog rice is known to have a carbohydrate content close to or exceeding that of rice [15]. In addition, the existence of a thermal process has an impact on decreasing the water content contained in the sample so that by using a by-difference calculation, the carbohydrate content increases [15].

pH value
In Table 4 showed the pH value of RTE liwet rice. Rice is estimated to have a pH that is classified as a low acid food, namely 6,00 to 6,70 [19]. Fried rice packaged in a retort pouch with a retort temperature treatment of 121 0 C for 15 minutes had a pH value of 6,41. Meanwhile, retort fried rice treated with a retort temperature of 116 0 C for 60 minutes had a pH value of 6,35 [3].  Table 5 presented the hedonic results conducted on untrained panelists. There were no significant differences in hedonic rating of all attributes. Panelists tend to like the color and aroma of the sample formulation D with a score of 5,00 ± 1,11 (somewhat like) and 4,74 ± 1,25 (grading scale 4 = neutral). When associated with the results of the physical color analysis, formulation C obtained the highest intensity of yellow color compared to the other four formulations. This shows that the panelists prefer bright yellow color. Meanwhile, if it is associated with the results of the physical texture analysis, it is known that the sample formulation C has the softest texture of the rice product. In other attributes such as color, aroma and taste, no significant differences were found between formulations. This makes formulation C quite popular and accepted by the panelists. In Table 6 presented the ranking results. Based on the results obtained, formulation C is the most favored sample with the smallest ranking value (indication of the smaller ranking value means the preferred/highest rating) of 2,34 ± 1,45. This is in accordance with the results of the overall hedonic test analysis which found that the product sample of formulation C was the most favored and accepted sample by the panelists.

Determination of the best formula
In Table 7 presented the results of the tabulation of scores for determining the best formulation. Formula C with the use of 30% corn analog rice obtained the lowest score based on the results of the MPE method.
With the acquisition of the lowest score indicates the highest ranking. Thus, formula C is the best formulation in producing RTE liwet rice with good and acceptable physicochemical and organoleptic characteristics.  *A: control (0% corn analog rice substitution); B: 20% corn analog rice substitution; C: 30% corn analog rice substitution; D: 40% corn analog rice substitution; E: 50% corn analog rice substitution.

Conclusion
Based on this study, it can be concluded that the development of liwet rice with corn analog rice substitution can be carried out up to 50%. The corn analog rice substitution formula had a significant effect on the proximate content and physical properties such as texture and color and had no significant effect on the acidity and organoleptic characteristics of RTE liwet rice in retort bag packaging. The best substitution result to produce RTE liwet rice with good physicochemical and organoleptic characteristics and sensory acceptance from all treatments was 30% substitution (formula C).