Formulation of purple yam (Dioscorea alata L.) and mangosteen peel (Garcinia mangostana L.) extract powder to ice cream making

Ice cream is a frozen food product made from milk with added sweetener. The addition of purple yam and mangosteen peel extract powder has the potential to enhance the product’s nutritional compounds. Purple yam and mangosteen peel extract powder have a high antioxidant content. The research aims to find out the best formulation of ice cream with the addition of purple yam and mangosteen extract powder on the physical and sensory properties, antioxidant activity, and anthocyanin compounds. This method used ice cream formulations with different concentrations of the two factors, purple yam, and mangosteen peel extract powder and continued to the organoleptic test, antioxidant test, anthocyanin test, ice cream melting speed, and overrun. Results obtained in the research showed the best three sensory properties based on the organoleptic test were 40% Purple yam + 0.2 % mangosteen; 40% Purple Yam + 0.6 % mangosteen; 50% Purple Yam + 0.4% mangosteen. The best overall formulation is 50% purple yam + 0.4% mangosteen peel extract powder with an overrun value of 2.53%, melting speed of 2.14%, and antioxidant activity of 89.63%, moreover 27.13 CyE/g of total anthocyanin. The research concluded that the additional purple yam and mangosteen peel extract powder could improve the ice cream’s antioxidant activity and the total anthocyanin.


Introduction
Purple yam (Dioscorea alata L.) is one of the local commodities with quite high productivity.The total production of purple yam in Indonesia in 2015 was 2,261,124 tons with a productivity of 160.53 quintals/hectare.The advantage of purple sweet potato is that it has an anthocyanin of ± 519 mg/100g wet weight [1].Purple yam has a purple color that is quite dense in its tuber flesh [2].The purple color of sweet potatoes is caused by the presence of natural dyes called anthocyanins.The anthocyanin components in purple yam consist of mono or diacetyl derivatives 3-(two-glucosyl) glucosyl-5glucosyl peonidin and cyanidin [3].Anthocyanin has a functional value that can act as an antioxidant.This makes purple yam a good prospect to be used as a functional food source.One of the innovations that can be made in purple sweet potato processing is making ice cream.
Ice cream has become a very popular product these days, especially during the summer season, which has prompted efforts to develop new and innovative products [4].Ice cream is a frozen food made from dairy products such as cream, then combined with artificial or natural flavors and sweeteners.Mix the mixture by stirring while reducing the temperature to prevent the formation of large ice crystals.Purple sweet potato ice cream can be combined with mangosteen peel powder to 2 increase its nutritional value and antioxidant properties.The use of mangosteen peel can be one way to utilize food waste.
Mangosteen peel is known to contain xanthone compounds with more than 50 kinds of derivatives that have been isolated.The content of these compound activity as antioxidant, antitumor, antiinflammatory, hypoallergenic, antibacterial, antifungal, antimalarial, and anticancer [5].Xanthones, anthocyanins, and polyphenolic compounds are active compounds that cause antioxidant activity in the mangosteen fruit, which is thought to be able to counteract free radical compounds that cause cell or tissue damage, degenerative diseases, and cancer.Until now, there has been no research that has developed ice cream products from purple yam and mangosteen peel extract powder used in making ice cream.Based on this background, research is needed to find out the best formulation of ice cream with the addition of purple yam and mangosteen peel extract powder on the physical and sensory properties, antioxidant activity, and anthocyanin compounds.

Materials
The tools used in this research were basins, beaker glass, mixer, refrigerator, spoons, ice cream cups, stoves, pans, spatulas, cutting boards, analytical scales, micropipette, tube rack, stopwatch, test tube, UV-Vis Spectrophotometer.The materials used in this research were mangosteen peel powder, purple yam, whipping cream, salt, skim milk powder, water, granulated sugar, DPPH, buffer solution, aluminum foil, and tissue.

Making purple yam paste.
The purple yam is peeled and washed thoroughly, cut into pieces.Steamed until cooked for 30 minutes and then pulverized using a spoon.

Making ice cream.
Ice cream was made differently for each treatment with the addition of purple yam paste as much as 30 g, 40 g, 50 g with a comparison of mangosteen peel powder 0.2 g, 0.4, 0.6.The purple sweet potato paste is mixed with the addition of 0.16 g of salt, 15 g of whipping cream, 20 g of skimmed milk powder, 15 g of granulated sugar, and 20 g of water, after which it is mixed to form a uniform dough.Then the resulting dough was stored for ± 35 minutes after, it was stored in the refrigerator (freezer) -30 o C for 5 hours and every.After 5 hours, it was taken out again to be mixed 3 times, after which it was stored for ± 24 hours.Then the resulting ice cream is put in a cup and stored in the refrigerator (freezer).

Observation parameters
2.3.1.Organoleptic test.Organoleptic testing was carried out based on the method from [6] with the attributes of aroma, color, taste, and texture using the hedonic method based on preferences.A total of 5-10 semi-trained panelists were directed to fill out a questionnaire with a rating scale of 1 to 5: 1 (dislike very much), 2 (rather dislike), 3 (fair), 4 (rather like), 5 (very like).

Antioxidant activity test.
The antioxidant activity testing was carried out using the DPPH.The antioxidant activity of sample extracts was determined by measuring the concentration of DPPH free radicals: 1 ml of sample extract was added to 1 ml of DPPH solution (0.16 g/L) in methanol, then shaken.The absorbance was measured after 30 minutes at room temperature at a wavelength of 517 nm.Methanol was used as a blank with the same processing as mentioned above.

Overrun.
The overrun was carried out based on the method from [7] and is calculated in the form of a percentage of overrun based on the difference in the volume of ice cream and Ice Cream 3 Maker (ICM) or ice cream mix.Overrun can be calculated using the formula, the difference between the volume of the mixture after stirring and before stirring, divided by the volume of the mixture before stirring, multiplied by 100%.
2.3.4.Melting speed.The melting speed test was carried out based on the method from [8].The melting time was measured by pouring the ice cream into the ice cream container, placing it in the freezer, leaving it for 24 hours, then storing the ice cream at room temperature and recording the original time until all the ice cream had completely melted.

Total anthocyanin.
Anthocyanin concentration can be measured using the pH differential method.A total of 0.05 ml of each sample was put into a test tube.The first test tube was added with 4.95 ml of potassium chloride (0.025 M) pH 1 solution, and the second test tube was added with 4.95 ml of sodium acetate buffer solution (0.4 M) pH 4.5.pH adjustment in the manufacture of potassium chloride buffer using HCl and pH adjustment in the manufacture of sodium acetate buffer using acetic acid.The absorbance of the two pH treatments was measured with a spectrophotometer at a wavelength of 516 nm and 700 nm after standing for 15 minutes.

Research design
The design of this study used a randomized design of a group of 2 factorials.A factor is the concentration of purple yam has 3 levels, namely: A1 : 30% A2 : 40% A3 : 50% B factor is the concentration of mangosteen peel extract powder oil has 3 levels namely: B1 : 0.2% B2 : 0.4% B3 : 0.6% Each sample will be tested for the organoleptic test.The best three formulations would be continued for chemical and physical analysis: antioxidant activity test, melting speed, overrun, and total anthocyanin.

Data analysis
The data will be analyzed with ANOVA (analysis of variance) and continued with Duncan's further tests to see any differences.The software used in processing data is Microsoft Excel 2019 and SPSS 16.

Results and discussion
The results of the organoleptic test on color parameters from 9 formulations ranged from 2.7 (rather like) to 4.03 (very like).Ice cream 50% purple yam + 0.2% mangosteen powder was the highest score for ice cream products with the acceptance level of panelists, while ice cream 30% purple yam + 0.4% mangosteen powder was the lowest score for ice cream products with an acceptance level panelist.Based on the resulting diagram, the results of testing each treatment experienced an increased rate, which can be seen in Figure 1.
Based on the results of the analysis of variance in the comparison of the concentrations of purple yam ice cream and mangosteen powder showed that the formulations had a significant effect at the 5% level (P <0.05), on the level of preference for product color, which can be seen in the graph, namely 50% purple yam + 0.4% mangosteen powder, 40% purple yam + 0.4%, 40% purple yam + 0.2% mangosteen powder, which produced the highest color preference due to the addition of purple yam which was highest than the other formulations.Purple yams contain a lot of anthocyanin pigments which give the ice cream an attractive purple color.The natural color of the purple yam gives a more stable purple intensity.Anthocyanins are natural pigments that have the potential to give natural colors to produce an attractive appearance in ice cream products.Different anthocyanin concentrations cause several types of purple yam to have different purple color gradations [9].The addition of mangosteen peel powder did not affect the color of the resulting ice cream.This was due to the low concentration of mangosteen peel powder added to the ice cream.Aroma is an important factor in determining the level of consumer acceptance of a product.The results of the organoleptic test on aroma parameters of 9 formulations ranged from 3.41 to 3.59.Ice cream with 40% purple yam + 0.2% mangosteen powder formulation was the highest score in the ice cream product with the acceptance level of the panelists.In comparison, ice cream 50% purple yam + 0.2% formulation is the lowest score for ice cream with the level of panelist acceptance.The results of each formulation based on the diagram were increased which can be seen in Figure 2. The results of an organoleptic test on taste parameters with 9 formulations of ice cream products ranged from 3.03 (rather like) -3.71 (very like).Ice cream 30% purple yam + 0.4% mangosteen powder formulation was the highest score for the acceptance level of panelists, while ice cream 40% purple yam + 0.4% mangosteen powder formulation was the lowest.The results of each formulation based on the diagram have increased, as shown in Figure 3.The results of the analysis of variance showed that formulation had a significant effect at the 5% level (P <0.05) on the level of preference for the taste parameters.The formulations that obtained the highest level were 30% purple yam + 0.4% mangosteen powder, 50% purple yam + 0.4% mangosteen powder, 30% purple yam + 0.2% mangosteen powder.It is influenced by the amount of purple yam added to the ice cream.Panelists preferred the concentration of the addition of purple yam which was quite high.The addition of a high concentration of purple yam will give a sweeter taste to the ice cream.Purple yam contain sucrose compounds which give a sweet effect so that ice cream becomes more delicious [10].
The results of the organoleptic test of texture from the formulations ranged from 2.8 (rather like) to 3.73 (very like).The formulations 50% purple yam + 0.2% mangosteen powder was the highest score, while the formulations 40% purple yam + 0.2% mangosteen powder is the lowest score for the level of panelist acceptance.The results of each formulation based on the diagram have increased, as shown in Figure 4.
The results of the analysis of variance in the comparison of the concentrations of the ice cream showed that the formulation had a significant effect at the 5% level (P <0.05) on the preference level for texture parameters.The formulations that obtained the highest hedonic scale of texture parameters were 40% purple yam + 0.2% mangosteen powder, 30% purple yam + 0.4%, 30% purple yam + 0.2% mangosteen powder.It caused the texture of the ice cream to be directly proportional to the overrun value.If the overrun value of ice cream is high, the texture will be soft and firm.The texture of ice cream is affected by the stabilizing agent glucomannan [10].Purple yam contains glucomannan, a stabilizer that affects the formation of texture and stabilizes the formation of ice crystals.The best formulation was determined based on the organoleptic test results by the panelists and continued by comparing the values of each formulation which gave significantly different results based on the results of the ANOVA test.The results obtained indicate the best three formulations, namely 40% Purple Yum + 0.2 % mangosteen peel extract powder, 40% Purple Yum + 0.6 % mangosteen peel extract powder, and 50% Purple Yum + 0.4% mangosteen peel extract powder.The three best formulations used as samples for the following analysis were the overrun test, melting speed test, antioxidant activity test, and total anthocyanin test.
Overrun in ice cream making is the percentage of volume development, the increase in the volume of ice cream between before and after freezing.The results obtained that the lowest value of overrun was the 40% purple yam + 0.2 mangosteen powder formulation.In comparison, the highest value was the 50% purple yam + 0.4% mangosteen powder formulation.The results of each formulation based on the diagram have increased, which can be seen in Figure 5.The results of the analysis of variance in the comparison of the concentrations of the ice cream showed the formulations had a significant effect at the 5% level (P<0.05) on the level of overrun.The average overrun value of the ice cream ranged from 1.57 % to 2.53 %.The highest overrun value was the 50% Purple Yum + 0.4% mangosteen peel extract powder formulation.It is due to the protein content in the purple yam, which is high enough.The higher protein content caused the overrun value to increase.It was because the protein content produces a lot of oxygen that is trapped due to the agitation process [11].
The results obtained in the formulations of ice cream were 40% purple yam + 0.2% mangosteen powder, 40% purple yam + 0.4% mangosteen powder, and 50% yam + 0.4% mangosteen powder.The results of each formulation based on the diagram had increased, as shown in Figure 6.The results of the analysis of variance in the comparison of the concentrations of ice cream showed the formulation had a significant effect at the 5% level (P<0.05) on the level of melting speed.The average melting resistance of the ice cream ranged from 1.53% to 2.14%.The 40% purple yam + 0.2% mangosteen powder formulation had the lowest melting resistance, while the highest melting resistance was owned by the 50% purple yam + 0.4% mangosteen powder formulation.It is caused by the large amount of fat content in ice cream.Purple yam is included in a carbohydrate-based fat substitute.The starch content will replace the function of fat in ice cream.The higher the fat content affected, the slower of melting speed of the ice cream.The fat content in ice cream can also result in a longer melting time.If the fat content in the ice cream is low, it can cause the resistance of the ice cream to be faster.The spread ingredients, especially protein, solids, and stabilizers, are lacking, and when the homogenization process is not quite right, it will cause the spread of the fat to be uneven so that the texture becomes rough and contains lots of rough and sharp ice crystals which causes the ice cream to melt quickly at room temperature [12].
The results obtained the lowest value of antioxidant activity was the 40% purple yam + 0.2% mangosteen powder formulation, and the highest was 50% purple yam + 0.4% mangosteen powder formulation.The results of each formulation based on the diagram had increased, which can be seen in Figure 7.
The results of the analysis of variance in the comparison of the concentrations of purple yam and mangosteen powder showed the formulations had a significant effect at the 5% level (P <0.05) on the level of antioxidants.It was seen that the average inhibition percentage in the ice cream ranged from 83.56% to 89.63%.The 40% purple yam + 0.2% mangosteen powder formulation had the lowest antioxidant content.In comparison, the highest antioxidant content was found in 50% purple yam + 0.4% mangosteen powder formulation and suggested that the higher the concentration of purple yam affected the higher antioxidant activity in ice cream.The dominant antioxidant activity in purple yam is due to its high anthocyanin content [9].The results obtained that the lowest was the 40% purple yam + 0.2% mangosteen powder formulation, and the highest was the 50% purple yam + 0.4% mangosteen powder formulation.The results of each formulation based on the diagram had increased, which can be seen in Figure 8.The results of the analysis of variance in the comparison of the concentrations of ice cream showed the formulations had a significant effect at the 5% level (P<0.05).It was seen that the average anthocyanin contained in ice cream ranged from 1.52 CyE/g to 27.13 CyE/g.The 40% purple yam + 0.2% mangosteen powder formulation had the lowest anthocyanin content, while the highest anthocyanin content was found in the 40% purple yam + 0.2% mangosteen powder formulation.This suggests that the higher addition of purple yam and mangosteen peel powder will also affect the anthocyanin levels of ice cream.Anthocyanins are contained quite a lot in purple yam [9] and mangosteen peel [13].The higher the addition of purple yam, the higher the ice cream's anthocyanin content.Anthocyanin is one of the compounds belonging to the flavonoid.Therefore, the anthocyanin content can affect antioxidant activity.The higher antioxidant activity can be caused by the presence of large amounts of anthocyanin pigments in the raw materials used [14].

Conclusion
The best sensory properties based on an organoleptic test are 40% Purple yam + 0.2 % mangosteen; 40% purple Yam + 0.6 % mangosteen; 50% Purple Yam + 0.4% mangosteen.The best overall formulation is 50% purple yam + 0.4% mangosteen peel extract powder.Physical characteristics of the best treatment overrun value of 2.53%, and a melting speed of 2.14%, it has a soft texture and is not easy to melt at room temperature.The best formulation had high antioxidant activity (89.63%) moreover 27.13 CyE/g of total anthocyanin.Total Anthocyanin (%) Formulations

Figure 1 .
Figure 1.The color of ice cream with different formulations.

Figure 2 .
Figure 2. The aroma of ice cream with different formulations.

FormulationsFigure 3 .
Figure 3.The taste of ice cream with different formulations.

Figure 4 .
Figure 4.The texture of ice cream with different formulations.

Figure 5 .
Figure 5.The overrun of ice cream from the best three formulations.

Figure 6 .
Figure6.The melting speed of ice cream from best three formulations.

Figure 7 .
Figure 7.The antioxidant activity of ice cream from the best three formulations.

FormulationsFigure 8 .
Figure 8.The total anthocyanin of ice cream from three best formulations.