Effect heating time and sugar on physicochemical and antioxidant activity of palmyra palm pericarp syrup

Palmyra palm pericarp syrup from Borassus flabellifer is rich in antioxidants and minerals and has a unique taste, making it a potentially beneficial functional drink. The study employed a completely randomized design with two factors: sugar addition (1:1, 1:1.5, 1:2) and heating time 80°C (13, 18, and 24 minutes). The research involved formulating the syrup, cooking it according to the treatments, and evaluating the results using two-way ANOVA. It was concluded that both treatments significantly influenced the syrup attributes, especially antioxidant activity. P1G1 has the highest % inhibition of 56.54 with a water content of 52.95%, ash content of 0.15%, crude fiber of 0.24%, viscosity of 3.28 PaS, and total dissolved solids of 44.67 °brix. The treatment did not significantly affect the colors L*, a*, and b*.


Introduction
Using waste products such as fruit peels is an effort to reduce food loss and food waste in Indonesia.Fruit peel is also used as a food additive to increase nutrition and bioactive components in a drink.For example, dragon fruit peel is an additional polyphenol and a source of antioxidants in ashitaba leaf powder tea [1].Pectin from passion fruit peel extract is added to beverage products such as juices to change their gelling characteristics, consistency, and texture [2].Thus, the use of waste products in product development can produce functional products that the sustainable domestic food industry can use.
The use of alternative food ingredients must be followed by ingredients that are rarely used in general so that the potential for food diversification continues to grow.One of the food sources that can be used for processing is palmyra palm or also known as lontar fruit (Borassus flabeliffer).This fruit also has anti-inflammatory, analgesic and antipyretic properties from its bioactive components.In addition, palmyra palm pericarp is a material that has not been used too much.Palmyra palm pericarp has a high antioxidant content that can be used as a functional food ingredient to reduce cancer risk.From previous research, palmyra palm pericarp has also been used as a raw material for making furfural [3].
The palmyra palm pericarp, which is high in antioxidants, can be utilized as a functional food in syrup form.The syrup has a long shelf life and can be consumed to get enough sugar intake.The process involved will involve the method of extracting the skin of the fruit to obtain the antioxidant potential of the peel of the palm fruit.In this study, two test variables were used for palmyra palm pericarp pericarp: adding sugar and heating time.Through previous research, it is known that there is a 1324 (2024) 012120 IOP Publishing doi:10.1088/1755-1315/1324/1/012120 2 correlation between the two variables in the characteristics and antioxidant composition of the syrup.Heat treatment affects the quality and appearance of anthocyanins.In addition to heating, adding sugar will increase the concentration of sweetness and viscosity of the resulting syrup.The concentration lowers the water content to the point where the water activity is low enough to support the degradation process, making the syrup a perishable and ready-to-drink product [4].So, it is necessary to observe the effectiveness of adding sugar and heating time as a step-in processing palmyra palm peel syrup, which can determine the attributes that contribute to the quality of palmyra palm pericarp syrup as an innovation in antioxidant-rich food products.

Palmyra palm pericarp syrup
Palmyra palm pericarp powder is obtained by cutting the palmyra palm pericarp thinly using a fruit knife and then grinding the skin finely using a food grinder into a powder.Palmyra palm pericarp powder is then macerated with water solvent with a ratio of 1:10.After being macerated for 48 hours, the extract from the pericarp of the palmyra palm was filtered to obtain a smooth extract from the pericarp of the palmyra palm.The next stage is the syrup preparation, which starts with dissolving the sugar according to a predetermined ratio in 100 mL of water and heating it for 2-3 minutes at 100℃ until the sugar is completely dissolved (Tabel 1).The sugar water is then cooled to room temperature.Next, mix the sugar water with 250 mL of palmyra palm pericarp extract and the additional ingredients citric acid and CMC.The mixture is reheated at 80℃ for a predetermined time and is stirred constantly.Finally, the syrup is cooled, filtered and placed in a container.Palmyra palm pericarp syrup is ready for further analysis.

Proximate analysis
For quantitative determination of proximate composition of palmyra palm pericarp syrup, moisture was determined using hot air oven (Association of Official Analytical Chemists; AOAC 952.08) [5] dried leaf samples at 105°C, until constant weight.Ash was determined according to gravimetric method (AOAC 930.30) [5] incinerated leaf samples at 550°C, until constant weight.Crude fiber was determined according to the enzymatic gravimetric method (AOAC 978.10) [5].

Viscosity analysis
Viscosity measurements were carried out on the yogurt samples at ambient temperature (25 °C), with a Brookfield viscometer (Brookfield Engineering Inc, Model RV-DV II Pro+) at 6 rpm with RV spindle.The spindle was used in accordance with the sample nature to get all readings within the scale [6]. 3

Color analysis
Color analysis was carried out using the CIE-Lab method based on The Commission International de I'Eclairage (CIE).Color analysis was carried out using a ZE 6000 color meter.The results of the data obtained are expressed in the parameters Lightness (L), redness (a*), and yellowness (b*) [7].

Total dissolved solids analysis
Total dissolved solids were measured using a refractometer according to AOAC 932.12 [5].The total dissolved solids content of palmyra palm pericarp syrup was determined using a handheld digital refractometer (Model: PAL-1, Atago co, Ltd, Tokyo, Japan) at 25°C and the total dissolved solids content was expressed as °Brix.

Antioxidant analysis
The method used to assess antioxidant activity is the Radical Scavenging Activity DPPH test.As much as 1 mL of palmyra palm pericarp syrup with 10 mL of distilled water.Sampling of 50 milligrams of palmyra palm pericarp syrup was then added with 50 ml of ethanol and brewed for 2 minutes to obtain 1000 ppm of fruit peel syrup extract.Next, 2 mL of palmyra palm pericarp syrup extract 1000 ppm was taken and diluted with 8 mL ethanol to obtain a solution with a concentration of 200 ppm (2/10 mg/mL) in a 10 mL volumetric flask.In the testing phase, 1 ml of 200 ppm solution was added with 3 ml of 40 ppm DPPH (0.01 mM), pipetting into a test tube.The test tube was then vortexed, covered with aluminium foil, and incubated in the dark for 30 minutes.Next, the absorbance was measured using a spectrophotometer at λ = 517 nm.From the data obtained, the calculation of antioxidant inhibition activity was used to determine antioxidant activity [8].Note: Different notations show significant differences based on the DMRT test (p<0.05).Capital letters compare the difference to the added sugar factor (read vertically).Lower case compares the difference to the heating time factor (read horizontally).The plus/minus symbols indicate there is interaction/no interaction between the two factors.

Effect of sugar and heating time on moisture content of palmyra palm pericarp syrup
As more sugar is added, the water content seems to decrease (Tabel 2).This result is to the literature, which states that sugar is hydrophilic [9].The nature of sugar that absorbs water is because sugar has hydroxyl groups in its chemical structure.The hydroxyl group will form hydrogen bonds with water molecules, and as the water content in the food decreases, the concentrate will thicken [10].Heating time has a significant effect on the resulting water content because heating time can reduce a substance's water content.When a material is heated, the heat energy causes the water molecules to gain energy and evaporate into the surrounding environment.Heating will accelerate the dissolution of sugar into water which can cause sugar to bind more water so that the water content will decrease [11].

Effect of sugar and heating time on ash content of palmyra palm pericarp syrup
The combination of sugar and heating time found the highest ash content in the P3G3 combination (0.29%) and the lowest ash content in the P1G1 combination (0.15%) (Tabel 3).Increasing the ash content gives the result inversely proportional to the decreasing water content.This increase in ash content occurs because the longer the time and the higher the drying temperature, the more water will evaporate from the dried material.In addition, high ash content also represents high nutritional inorganic minerals in the syrup (calcium, potassium, and phosphorus), high impurities or both [12].Note: notations show significant differences based on the DMRT test (p<0.05).Capital letters compare the difference to the added sugar factor (vertical). Lower case compares the difference to the heating time factor (horizontal).The plus/minus symbols indicate there is interaction/no interaction between the two factors.Note: Different notations show significant differences based on the DMRT test (p<0.05).Capital letters compare the difference to the added sugar factor (vertical). Lower case compares the difference to the heating time factor (horizontal).The plus/minus symbols indicate there is interaction/no interaction between the two factors.

Effect of sugar and heating time on crude fiber of palmyra palm pericarp syrup
The addition of sugar and heating time significantly influenced the ash content of the sample.However, for G3, the ratio of 1:2 does not have a significant effect on the heating time factor.The same thing was also seen in the P3 factor regarding adding sugar, which did not provide a significant difference.Apart from that, a significant interaction was found between adding sugar and the heating time.
The longer the heating time and the more sugar added, the higher the crude fiber content.The longer the heating time used to make palmyra palm pericarp syrup, the more water content will evaporate.The more vaporized water content causes the total solids in food to increase, including crude fiber.The crude fiber content increases as a result of heating-induced fiber dissolution from the sugar in the syrup [13].Note: Different notations show significant differences based on the DMRT test (p<0.05).Capital letters compare the difference to the added sugar factor (vertical). Lower case compares the difference to the heating time factor (horizontal).The plus/minus symbols indicate there is interaction/no interaction between the two factors.

Effect of sugar and heating time on viscosity of palmyra palm pericarp syrup
Based on the data results in Table 5, the highest viscosity was 28.40 Pa.S from a combination of 24 minutes of heating time and 1:2 sugar addition, while the lowest viscosity was 3.28 Pa.S from a combination of 13 minutes of heating time and 1:1 sugar addition.The viscosity of the palmyra palm pericarp syrup produced was significantly influenced by adding sugar content (P<0.01).The viscosity of palmyra palm pericarp syrup is directly proportional to the sugar added.This is caused by adding sugar, which will bind free water during heating and dissolve in water to form a thick solution.In water, sugar will dissolve and turn into a soluble solid.Total dissolved solids will rise as more sugar is added.The viscosity of the resulting syrup will increase due to the increase in total dissolved solids.Thus, sugar can also be a source of solids to increase the viscosity of a substance [14].Constant heating over a longer duration causes water to evaporate more easily and frequently, thereby reducing viscosity [15].Note: Different notations show significant differences based on the DMRT test (p<0.05).Capital letters compare the difference to the added sugar factor (vertical). Lower case compares the difference to the heating time factor (horizontal).The plus/minus symbols indicate there is interaction/no interaction between the two factors.

Effect of sugar and heating time on total dissolved solids of palmyra palm pericarp syrup
Table 6 showed that total dissolved solids tend to increase with increasing sugar and heating time.
Based on the results, the highest dissolved solids were in the P3G3 combination, followed by P2G3 and P3G2 as the three treatment combinations with the highest total dissolved solids.Adding sugar can add solidity to palmyra palm pericarp syrup.The composition of fiber and minerals found in palmyra palm pericarp syrup will also increase the total solids in the syrup.Therefore, the data results can be said to be by the literature because the higher the sugar concentration used in making syrup, the higher the value of the dissolved solids [16].Note: Different notations show significant differences based on the DMRT test (p<0.05).Capital letters compare the difference to the added sugar factor (vertical). Lower case compares the difference to the heating time factor (horizontal).The plus/minus symbols indicate there is interaction/no interaction between the two factors.

Effect of sugar and heating time on antioxidant activity of palmyra palm pericarp syrup
Table 7 shows that the DPPH inhibition decreases with increasing sugar and heating time.Based on the DPPH inhibition range theory by Jadid [17] samples with a combination of P1G1, P1G2, and P1G3 treatments are included in models with high DPPH inhibition.The P3G3 treatment combination sample was included in the sample with the lowest DPPH inhibition.Meanwhile, the other samples, namely P2G1, P2G2, P2G3, P3G1, and P3G2, are included in the moderate inhibition range.The model with the highest DPPH inhibition was sample P1G1, with an inhibition percentage of 56.54%, while sample P3G3, the smallest sample, had a DPPH inhibition percentage of 23.81%.The model with the lowest heating time and smallest sugar addition had the highest DPPH inhibition effect.The addition of sugar provided significant results on the percentage of inhibition of palmyra palm pericarp syrup.The higher the sugar added, the more DPPH inhibition levels tend to decrease.This is because the presence of methylation groups and the reduction of H atoms in sugar reduces antioxidant activity as a hydrogen donor for free radicals; therefore, the more sugar added, the lower the antioxidant activity [18].
In Table 7 of the analysis results, the heating time was also detected to have a significant influence (P<0.05).This is caused by heat, which can cause antioxidants in food to be damaged or degraded.Palmyra palm pericarp syrup contains bioactive compounds with antioxidant capabilities (carotenoids, flavonoids, and tocotrienols).Prolonged heating can also change the structural properties of components in palmyra palm pericarp syrup, such as proteins and phenolic chemicals, reducing the effectiveness of its antioxidants [19].Note: Different notations show significant differences based on the DMRT test (p<0.05).Capital letters compare the difference to the added sugar factor (vertical). Lower case compares the difference to the heating time factor (horizontal).The plus/minus symbols indicate there is interaction/no interaction between the two factors.

Effect of sugar and heating time on color of palmyra palm pericarp syrup
Table 8, palmyra palm pericarp syrup, shows that the heating time does not significantly affect the redness of the syrup; however, for the addition of sugar, there is a significant difference.The a* value range is 26.98 -14.46; this shows that palmyra palm pericarp syrup has a dominant red color.The red color of palmyra palm pericarp syrup is caused by its carotenoid content.Judging from the overall average, adding sugar tends to reduce the a* (redness) value.This is to Handani's research for panna cotta, where adding sugar concentration had a significant effect on lowering the a* value of palmyra palm pericarp syrup (P<0.05)[20].The b* value range is 12.31 -7.71, which shows that palmyra palm pericarp syrup is yellow, produced from carotenoid components with natural red, orange, and bright yellow pigments.

Conclusion
Adding sugar and heating time significantly reduced water content and increased ash content, crude fiber, viscosity, and total dissolved solids.Siwalan fruit rind syrup is also known to have the potential

Table 2 .
Effect of sugar and heating time on moisture content of palmyra palm pericarp syrup

Table 3 .
Effect of sugar and heating time on ash content of palmyra palm pericarp syrup

Table 4 .
Effect of sugar and heating time on crude fiber of palmyra palm pericarp syrup

Table 5 .
Effect of sugar and heating time on viscosity of palmyra palm pericarp syrup

Table 6 .
Effect of sugar and heating time on TDS of palmyra palm pericarp syrup

Table 7 .
Effect of sugar and heating time on antioxidant activity of palmyra palm pericarp syrup

Table 8 .
Effect of sugar and heating time on color of palmyra palm pericarp syrup