Isothermic model of porang tuber (Amorphophallus muelleri B) flour

Porang tuber (Amorphophallus muelleri B) is a tuber from the Araceae family with a high glucomannan content (15-64% dry basis). Things that can be done to extend the shelf life of porang tuber flour are by doing the flouring process. This research aims to determine the isothermic curve model of Porang tuber (Amorphophallus muelleri B) flour, namely, the isothermic curve model used to estimate the equilibrium moisture content about the rh of storage. The research method used was to store samples of porang tuber flour in a desiccator with an rh interval of 17-80%. Storage was carried out until the sample’s water content reached equilibrium. Parameters of water content and determination of the best model based on the highest R2 value at the end of storage of porang tuber samples while in the desiccator. The results of the research that has been done show that a material’s water content is affected by temperature and storage rh. To determine the best model, it is shown with the model that has the highest R2 value. The Henderson model and Chung-Pfost model is the model that has the highest R2 value. The value obtained at 30 °C is 0.9556, and at 40 °C is 0,9838. The model with the highest R2 value indicates that the model is the best and most appropriate model that can be used to describe the best water absorption in porang tuber flour.


Introduction
Drying lowers a material's water content until it reaches a specific moisture content to minimize product damage brought on by biological and chemical processes.Drying is a process of transferring energy to evaporate the water in the material, allowing it to reach a specific water content and reducing food deterioration.When there isn't enough water for the bacteria and enzymes to function, their activity declines, leading to a longer shelf life.The drying procedure lowers the water content rather than sterilizing the object.It is essential to manage dried goods, so their water content stays low and their quality is not compromised [1].
The material's moisture content equilibrium is one significant factor in the drying process.When the outside vapor pressure equals the material's internal water, the material's equilibrium moisture content is reached (RH and temperature).Every food component has a certain water content compatible with its surroundings [2].
The equilibrium moisture content is also crucial when storing items for an extended period.The material will adjust to these conditions by increasing its moisture content until it finds equilibrium with 1230 (2023) 012173 IOP Publishing doi:10.1088/1755-1315/1230/1/012173 2 its surroundings in a storage space with a high RH.The material will be vulnerable to mold because of its high water content [3].
Therefore, consuming food stuffs with a low glycemic index can help insulin work by reducing the risk of rising blood glucose levels.The development of sago for diabetics can be applied to interlude foods fortified with nutritional content from other foodstuffs to minimize the risk of increasing blood glucose levels.Sago has high carbohydrate levels and a low glycemic index but is also common in protein and vitamins.The solution that can be done is fortifying the product with beta-carotene components from carrots and protein from snakehead fish to increase its nutritional content [4].
One of the herbaceous bushes with underground tubers that grow in forests and is currently widely farmed, especially in Indonesia, is called porang tuber.Amorphophallus muelleri B, also known as porang tuber, is a plant that has multiple uses, including food, adornment, and medicine.Because the glucomannan levels are at their maximum when the plants fall, porang plants are typically collected after they do.Although porang tuber is a raw material for producing mannan powder, which has a high economic value, porang tuber has a great deal of potential for production.Still, it has not been managed efficiently or optimally [5].
Glucomannan content is high in porang tubers.The most significant source of glucomannan in Indonesia itself is a compound known as water-soluble fiber and complex carbohydrates that are believed to have originated from plants in Poland.One of the thickest dietary fibers, glucomannan, is employed in the food industry and has high water absorption.It also produces a gel-like effect.They were used as a binder, thickening, preservative, and fat replacement.It can also be used for various things, like film components for edible films and adhesives [6].
Much research hasn't been done on the equilibrium moisture content of porang tuber flour.This study was designed to examine the equilibrium moisture content of porang tuber flour at varied RH levels and storage room temperatures.We'll assess the isothermic model of material equilibrium moisture content based on the relative humidity level at a specific temperature.The best model among several potential models that could represent the properties of the tested porang tuber flour underwent evaluation.

Materials
Digital scales, a cutter, a blender, an 80 mesh filter, aluminum foil, a thermometer, and 12 desiccators containing salt solution with a roughly 17-80% RH range were the tools utilized in this investigation.Six desiccators were used for each storage at room temperature, room temperature, and 40 o C. Porang tubers were the study's materials (Amorphophallus muelleri B).

Research procedure 2.2.1. Preparation stage.
The preparation of materials in this study is.a. Peel the skin of the Porang tuber using a knife (cutter).b.Washing the peeled Porang tubers using clean water to remove dirt on the Porang tubers.c.Slice small samples of Porang tubers using a knife (cutter).

Drying stage.
The process of drying the material in the study is a.Prepare slices of Porang tubers that are dried in the oven.b.Weigh the empty container without ingredients, then weigh the container containing the Porang Tuber sample again to calculate the initial weight of the material.c.Putting the dried sample into the oven at 60 ℃.d.Weigh the sample and stop when the weight of the material has been constant.e. Grind the sample into small partieces (flour) f.Sieve the flour using an 80 mesh sieve ).b.Each desiccator was filled with two samples of porang flour.c.Every two weeks, samples were weighed.After the sample weight stabilized, the importance was halted.This storage will endure for two to three months until a steady weight is attained.They removed the sample from the desiccator after constant sample weight.d.Bake the ingredients for 72 hours at 105 °C (dry weight of components) for the importance of the final solid.e. Calculate the water content of the sample.

Observation Parameters
One of the variables to be monitored in this study is the sample's weight, which will be converted into the sample's wet and dry moisture content.That is the level of water that was at balance.The equilibrium moisture content and water activity (aw) at each storage temperature will be graphed to produce an isothermic curve.

Effect of temperature and RH on moisture content
A decrease in temperature during storage can increase the amount of bound water followed by an increase in water activity (aw).In determining the water content, measurements can be made using the oven method and are expressed in percent dry weight (% bk).Then the determination of the isothermal curve can be continued, which is described by the combination of water activity and equilibrium humidity in the storage room at a certain relative humidity value.The salt used in this study consisted of 6 types of saturated salts namely NaOH, MgCl2, K2CO3, NaNO2, KCl, and NaCl.With an RH range between 17-80%.Samples were stored at 2 temperatures, namely 30 ℃ and 40 ℃ with each salt solution and different RH.Storage is carried out until the sample reaches an equilibrium point condition which is marked by the results of constant weighing.This aligns with [7].Where the product is in an equilibrium state when its water vapor emissions are in equilibrium with its surroundings.In this situation, the product's weight does not change desorption (water release) and adsorption (absorption) occur instead.
The results of observations of the water content of porang tuber flour while drying it at two different temperatures, namely 30 °C and 40 °C, are as follows.Based on the research results in Figure 1 and Figure 2, it can be seen that the equilibrium values obtained for each solution with a different RH factor and using two storage temperatures produce different water content.Where Table 2 shows that a temperature of 30 °C has a higher increase in water content compared to a temperature of 40 °C.The same thing happened in Table 3 for the determination of dry basis moisture content.From Table 2 it can be seen that a water content (Wet base moisture content) of about 10% can be maintained at 64% RH (NaNO2 salt solution).This shows that porang flour must be stored at a maximum RH of 64% to ensure the moisture content is stored according to SNI. [8].
In addition to being affected by different storage temperatures, the storage RH factor is also an important factor affecting sample storage.Table 2 and Table 3 show that the equilibrium moisture content of each solution decreases and increases, and the higher the RH in each salt water, the higher the water content and vice versa.The increase and decrease in sample weight show the phenomenon of sorption properties.In addition, the temperature is the most important factor in the drying process.It can be seen that the value of water activity (aw) is affected by temperature, the higher the storage air temperature, the lower the water activity.This is consistent with the claim of [9] that, for a given temperature, a rise in relative humidity (RH) lengthens the time it takes for a substance to achieve its equilibrium moisture content.Greater content quality.A rise in temperature speeds up reaching equilibrium at the same relative humidity level, and the equilibrium humidity value is also higher.

Best Model Testing
In this study, three mathematical models were used.The model is an isothermic model that is tested to detect the best model.The three models are the Henderson, Oswin, and Chung-Pfost models.As for testing the three models, it can be done using MS.Excel Solver.MS usage.Excel Solver to determine the values of the constants and R 2 in the model.The constant value was based on the data in Table 4 above, which depicts the outcomes of storing samples of porang flour at two different storage temperatures.The Henderson model at 30 °C and the Chung-Pfost model at 40 °C are two models that, according to the data from the test results of the three models with R 2 provided in the table, are very close to having a value of one.At 30 °C, the R 2 value is 0.9556, while at 40 °C, it is 0.9838.The model with the highest R 2 value is the most effective and appropriate for describing how porang flour absorb water [10].[11] stating that the Henderson model and the Chung-Pfost model are the most appropriate models for predicting isothermic curves, the Henderson model is a model that can be used over a wide aw range

Conclusion
The Henderson model at 30 °C and the Chung-pfost model at 40 °C are the best isothermic models to predict the behavior of the equilibrium moisture content of porang flour in the range of 17-80% RH.At 30 °C and 40 °C, respectively, the two models have the most excellent R 2 values of 0.9556 and 0.9838.
Porang flour must be kept in humidity levels lower than 64% to meet the water content requirements based on SNI porang tuber flour.At a moisture level higher than the maximum moisture content (10% allowed by SNI), the moisture content of porang tuber flour will reach equilibrium.

2. 4 . 1
Moisture content.By being aware of the material's dry weight after it has spent 72 hours in an oven at 105 °C.Then, find the percentage value for the dry and wet basis moisture content.Wet basis moisture content;

2. 4 . 2
Isothermic model testing.The model to be tested is the Henderson, Oswin, Chung, and Pfost model, which is presented as follows; Henderson w = A[-ln (B log (1 − a w )] 2 moisture content (%), A = Constant value, B = Constant value, Aw = Water activity /RH (%).basis moisture content (%), A = Constant value, B = Constant value, aw = Water activity RH (%)/100.2.4.3Best Model Determination.The MS. Excel Solver will determine the constants A and B values in the above three isothermic models.The W value (equilibrium moisture content of the material on a dry basis) and the aw value for each storage desiccator RH are the input data supplied into the MS Excel Solver to determine the two constants.The Excel Solver will automatically search the tested isothermic model for constant values.The RSQ MS function determines the R 2 value for each model.Excel.The model with the highest R 2 value is the best isothermal version.

Figure 2 .
Figure 2. The equilibrium moisture content of porang tuber flour at 30 ℃ and 40 ℃ dry basis moisture content.

Figure 3 .
Figure 3. Henderson model prediction compared to observational data at 30 °C.

Figure 4 .
Figure 4. Model Chung-pfost prediction compared to pengamatan data at 40 °C.Based on Figure 3 and Figure 4 it can be seen that the Henderson model and the Chung-Pfost model are the best models that can describe water absorption in porang tuber flour which is characterized by the highest R 2 value compared to other predictive models, namely the Oswin model.The level of suitability of the drying model, namely the Henderson model and the Chung-Pfost model, is shown in the prediction of the model relationship and the results of observations at two different temperatures.This prediction shows the tendency of the prediction value of the Henderson model and the model Chung-Pfost to the closer observation value where the right model to describe the isothermic curve on porang tuber flour measuring 80 mesh is the Henderson model.This prediction shows that the drying model that corresponds to the best water absorption in flour has a fairly low water activity, which follows the statement made by[11] stating that the Henderson model and the Chung-Pfost model are the most appropriate models for predicting isothermic curves, the Henderson model is a model that can be used over a wide aw range Siege stage.a. Place the Porang Tuber flour sample in a 7 cm diameter aluminum foil container that weighs approximately 5 grams (sample + container), and then keep it in 6 desiccators that have a specific RH level and a saturated salt solution in each (Sodium Hydroxide, Magnesium Chloride, Potassium Carbonate, Sodium Nitrite, Sodium Chloride, and Potassium Chloride).The six desiccators were kept in a storage box with a temperature of 40 o C and at ambient temperature (about 29-30 o C 3 2.2.3.

Table 1 .
Results of measurement of moisture content before storage.

Table 2 .
Shows the results of determining the moisture content of the porang tuber flour's wet basis equilibrium.
Figure 1.The equilibrium moisture content of porang tuber flour at 30 ℃ and 40 ℃ wet basis moisture content.

Table 3 .
Results of measuring the dry basis equilibrium moisture content (Kabk) of porang tuber flour.

Table 4 .
Value of constants and R 2 .