The effect of sodium trimetaphosphate on the physical and functional characteristics of banggai yam starch

Banggai yam starch as well as other types of starch is known to have physical and functional properties which cause the use of starch in the limited reliability industry. Therefore, it is necessary to improve physical properties by modifying the proud yam starch by phosphorylation. Research to determine the sodium trimetaphosphate (STMP) concentration wich gives the best tendency in the modification of proud yam starch by phosphorylation based on its physical and functional characteristics. Research uses a completely randomized design one factor consisting of a concentration of STMP 2, 4, 6, 8, 10, 12% and native starch as a comparison. The variable of observations included emulsion separator volume, viscosity, water holding capacity (WHC), oil holding capacity (OHC), swelling power, and solubility. The results showed that the emulsion separator volume, WHC, swelling power, and solubility starch modification is smaller than native banggai yam starch, while at viscosity starch modification is greater than native banggai yam starch. In the analysis OHC fluctuates as concentration increases. The STMP concentration that gives the best tendency is 4%. The value generated at this concentration is emulsion separator volume 90%, viscosity 577 Cp, WHC 0.94 g/g, OHC 2.84 g/g, swelling power 4.60 g/g, and solubility 0.17%.


Introduction
Banggai yam plant (Dioscorea alata L) is very potential as a source of calories because it contains 88.1% carbohydrates and 1.67% sugar, 16.7% starch, 2.9% minerals, 0.7% fat and 9.75% protein.Banggai yam starch contains quite a variety of starch levels, from the lowest variety Buan Mbol 73.50% and the highest Doso 99.6% [1].The main nutritional value of cassava is starch which ranges from 60-85% dry weight and the protein is quite high from the tuber group.According to [2] proved that sweet potato consumption can significantly reduce blood sugar levels and body weight compared to controls.
Chemical modified starches are also known as starch derivatives.Chemical modification can be carried out by means of oxidation, etherification, esterification/phosphorylation, depending on the IOP Publishing doi:10.1088/1755-1315/1253/1/012127 2 desired characteristics of the modified starch [3].Native starches are generally of limited use and therefore need to be chemically modified.According to previous researchers, there has been a separate study on the modification of butyrilized and acetylated banggai yam starch.However, there has been no study of phosphorylation (crosslinking).
Chemical compounds that can be used to cross-link modified starch are sodium trimetaphosphate (STMP), sodium tripolyphosphate (STTP), phosphorous oxychloride (POCl3), and others.Based on these problems, the research examines the physical and functional characteristics of banggai yam starch as a result of phosphorylation to produce cross-linked starch.Cross-linking is another method that can be used to modify starch.The advantage of using this cross-linking method is that it can produce starch that small swelling power, resistant to heat and acidic mediums.Furthermore, phosphorylation can to improvement the viscosity, texture and clarity of starch pastes become more stable.On the other hand, this method has drawbacks, namely making the sediment volume, elastic gel, solubility and stable in freezing [4].STMP with the empirical formula Na3P3O9 is a sodium metaphosphate, that is, the sodium salt of trimetaphosphoric acid with the characteristics of a colorless solid that finds particular application in the food and construction industries.
According to [5], one of the factors that influence the success of crosslinking modification is the STPP concentration used, if the STPP concentration is correct, there will be an increasing in amylose content and swelling power while decreasing in solubility.However, if the STPP concentration used is too high, it will increase the phosphate residue in the modified starch, where the maximum allowed phosphate residue is 0.4% with a maximum Degree of substitution (DS).The previous research reported the phosphorylation in starch molecules was to resistance the retrogradation process, resistance to heat, acid-base and water [6].Therefore, the objectives research was to study the influence of STMP on the physical and functional characteristics of banggai yam starch obtained through phosphorylation

Materials
The main material for the research was banggai yam starch obtained from the Banggai Regency, Central Sulawesi.The chemicals used included STMP, NaOH, HCl, KOH, ethanol and acetic acid from Merck.The other analytical reagents were obtained at the Agroindustry Laboratory of the Faculty of Agriculture, Tadulako University.

Research design
In this research, a completely randomized design used one factor that is of STMP concentrations of 2, 4, 6, 8, 10 and 12% and native banggai yam starch as a comparison which was repeated three times.

Phosphorylation of banggai yam starch
Phosphorylation of banggai yam starch was done method that developed by [7] and [8] with a few modified.The mixture of distilled water (225 mL) and banggai yam starch (100 g) were stirred for 60 min at room temperature.After that, the mixture was raised to a pH of 10.5 by adding 5% NaOH while still stirring, then STMP 2, 4, 6, 8, 10 and 12% (w/v) were added.The phosphorylation lasted for 45 min at 40 o C a pH of 10.5.After the phosphorylation was complete, 0.5 N HCl was added to the mixture until the pH was 4.5 to stop the phosphorylation.After the completion of phosphorylation, then proceed with the precipitation and washing of the mixture using water three times and ethanol once, then drying with a cabinet drier at 50 o C for 12 h until the moisture content is 10-12%, pulverized, and filtered through a100 mesh sieve.The results of phosphorylation produced phosphate banggai yam starch at various concentrations of STMP reagents.

Water and oil holding capacity.
The WHC and OHC were analyzed according to the method by [9] with a few modified.Briefly, In the test tube, 250 mg of samples and 25 mL of water or oil were added, after which stirring was carried out for 5 min and then the mixture was left for 60 min at room temperature.The centrifugation process was carried out on 3,500×g for 30 min.After centrifugation, the residue is weighed and then the WHC and OHC were determined as g of water or oil, respectively per g of sample.
2.4.4.Swelling power and solubility.Swelling power and solubility were analyzed according to the method development by [10].The suspension consisting of starch and distilled water (1%, w/v) was put in a test tube and then weighed (W1).The next process is heated at 80 o C for 30 min and after that it is cooled down to room temperature.Centrifugation was carried out at 3400 rpm for 30 min, then the residue and liquid were separated.After that, the residue in the test tube was weighed (W2).Swelling power (dry bases) calculated as follows: Swelling power (g/g) = (W2 − W1) sample weight (1) Five mL of liquid was taken, then put in a cup and dried at 110 o C until it reaches a constant weight.The residue that is there after drying shows the amount of starch that is soluble in water (%).

Statistical analysis
All parameters were determined in triplicate.The results were analyzed through the application of one-way ANOVA using SPSS version 22 (SPSS Inc., Chicago, IL, USA).The means were compared with Duncan's multiple tests and the statistics significant was defined at p0.05.

Emulsion separator volume
An emulsion is a mixture of ingredients forming a stable suspension.This needs to be analyzed to determine the stability of the emulsion formed from phosphorylation of banggai yam starch.The results of the variance show STMP treatment in modified phosphorylated banggai yam starch did not have a significant effect on the volume of the emulsion separator.The average volume value of the emulsion separator is presented in Figure 1.Seen from Figure 1, the average volume of the emulsion separator shows the highest emulsion separator volume obtained from native starch.This is due to the less stability of native starch because banggai yam starch has OH groups which are present in native starch granules which cannot combine with the tween, besides that, the temperature used is relatively high (> 80°C), the potential for gelatinization [11].

Viscosity
Based on the analysis of the viscosity of the STMP treatment in the modified banggai yam starch phosphorylation has a significant effect on the viscosity.The viscosity value is presented in Figure 2.
In Figure 2, it can be seen that the highest value of viscosity analysis at various STMP concentrations of 4% and 8% is 577 Cp, while the lowest viscosity value is for native starch, namely 341 Cp.The viscosity has a tendency to increasing with the increasing concentration of STMP.This is because there is a cross-linked modified banggai yam starch that will interact with phosphate compounds which can react with the-OH group in the amylose or amylopectin structure, the crosslinks that are formed will strengthen the phosphate bonds in the starch chain, thereby reducing the swelling strength, cold viscosity, tensile strength absorb water and increase the gelatinization temperature and hot viscosity of starch paste.

Water and oil holding capacity
The results of the variance show STMP treatment in the phosphorylation of modified banggai yam starch did not have a significant effect on WHC and OHC.The average WHC and OHC values are presented in Figure 3. Seen from Figure 3, the average WHC of modified starch has a lower WHC than native starch.According with the results by [12] reported the average WHC and OHC of acetylated banggai yam starch had greater WHC and OHC compared to native banggai yam starch.The WHC increased with increasing STMP concentration up to 10%, and then decreased at 12% concentration.This is in accordance with the results by [13], that the water absorption capacity of gembili starch modified by crosslinking with sodium tripolyphosphate is lower than native starch.The ability to absorb water in starch is influenced by the presence of hydroxyl groups present in starch molecules.If the number of hydroxyl groups in starch molecules is very large, then the ability to absorb water is very large.According to [10] found that WHC of the acetylated sword bean starch at DS 0.14 was higher than that of the native starch.The highest OHC was obtained from modified tapioca starch with an STMP concentration of 10%, while the lowest was at a concentration of 2%.This is because the starch granules become damaged so that the granules stretch and make it easier for oil to enter the tightly bound granules.According to [14] reported that the OHC of the acetylated banana was higher than that of the raw banana.

Swelling power and solubility
The results of the variance show STMP treatment in the phosphorylation of modified banggai yam starch did not have a significant effect on swelling power and solubility.The average swelling power and solubility values are presented in Figure 4.As seen from Figure 4, the average swelling capacity of the modified starch is smaller than that of the native banggai yam starch.This is due to the increase in temperature (heating) causing the hydrogen bonds to stretch, so that water is easily imbibed into the starch granules which causes the starch granules to swelling.These were similar to the results of [15] that swelling power of the acetylated oat β-glucan was higher than native starch.
The modified starch solubility test results were smaller than native starch.This is because when the starch is heated, the water will enter the starch granules, and the starch will expand into a starch paste.These results were similar to the earlier report of [16] that solubility of the acetylation of acetylated potato starches preparations increased their solubility in water and water absorbability was than native starch.

Conclusion
The STMP concentration of 4% gave the best tendency towards modified phosphorylated banggai yam starch.Banggai yam starch resulting from STMP phosphorylation at 4% can be used as an emulsifier based on WHC and OHC.

Figure 1 .
Figure 1.Emulsion separating volume of native and phosphate banggai yam starch at various STMP concentrations.

Figure 2 .
Figure 2. Viscosity of native and phosphate banggai yam starch at various STMP concentrations.

Figure 3 .
Figure 3. WHC and OHC of native and phosphate banggai yam starch at various STMP concentrations.

Figure 4 .
Figure 4. Swelling power and solubility of native and phosphate banggai yam starch at various STMP concentrations.
Suspended 1 g of starch with 9 mL of distilled water into a test tube with the addition of 1 mL of tween liquid.Then heated using a waterbath shaker at 80 o C for 30 min.After the emulsion is made, it is put in a scaled test tube, then stored at room temperature.The volume of phase separation was measured at room temperature every 24 h, 48 h and 72 h.2.4.2.Viscosity.Determination of viscosity was measured using a visikometer brand MYR KLEB VK 2000.The first step was to weigh 13 g of the sample, suspend it with 130 mL of distilled water, then heat it until it boils until the starch dissolves, then let it stand.The spindle needle is mounted on the viscometer.The sample's viscosity was measured.The viscosity of the sample can be determined immediately by reading the scale indicated by the after a certain number of revolutions.