Utilization of banana peel as functional ingredient in pudding: physicochemical and sensory aspects

This study aimed to investigate the physicochemical characteristics and sensory perception of pudding with banana peel addition. Banana peel from two varieties, Ambon and Kepok, was incorporated into pudding formulation with a concentration of 3% and 6%, respectively. All samples were analyzed for physicochemical properties (moisture content, dietary fiber content, texture, color, and syneresis) and sensory penalty analysis using the JAR (Just About Right) method. Pudding with Ambon peel addition was superior in dietary fiber content, hardness, and sensory acceptance. However, pudding with Kepok peel performed better lightness and syneresis. Higher banana peel concentration significantly increased dietary fiber content and overall liking but significantly decreased pudding syneresis. The JAR penalty analysis revealed that the lightness and the banana and milk aromas affected the products’ overall liking. Pudding with 6% Ambon peel showed an optimum performance among samples, containing 88.76% moisture content, 5.57% dietary fiber, 1.29 N hardness, 2.5% syneresis, and 7.14 hedonic score, indicating this product was perceived as like by panellist. According to the mean drops analysis, this product should improve the lightness and milk aroma to gain consumer acceptance.


Introduction
Banana is a fruit widely produced and consumed in tropical and subtropical regions, especially in Indonesia.Indonesia is known as one of the centers of banana diversity.Cavendish (Musa cavendishii), Kepok (Musa paradisiaca Linn), and Ambon (Musa paradisiaca) are several varieties of Indonesian bananas [1].Bananas are consumed directly as fruit or processed into other products such as fried bananas, banana jam, and chips.According to international trade, bananas were at fourth rank in gross value production of crucial global food crops after rice, wheat, and corn [2].The average consumption of bananas is 12 kg per capita.Banana production is increasing yearly and has reached 117 million tons in the last 20 years.However, this causes an increase in the amount of banana peel waste, which can have a detrimental impact on the environment and the economy.About 36 million tons of banana peels have yet to be utilized in a year.Banana peels are generally used as organic fertilizer and animal feed; however, the utilization still needs to be considered optimal [3].
Banana peels weigh about one-third of the total weight and are reported to contain high nutrients, consisting of 63.82% carbohydrates, 12.67% fiber, 0.89% fat, 3.23% protein, 19.85 mg/100 g calcium, 15.15 mg/100 g iron, 1.72 mg/100 g zinc, and 9.05 mg/100 g manganese [4].Banana peels also contain vitamin B6, which can lower cholesterol and stabilize metabolism.The high content of dietary fiber can help expedite the digestive system.In addition, it also contains antioxidants that protect the body from 1324 (2024) 012117 IOP Publishing doi:10.1088/1755-1315/1324/1/012117 2 free radicals and can act as an antidepressant [5].Perla et al. [6] reported an improved nutritional value of spaghetti with banana peel flour addition.In addition to providing health benefits, the taste of this product was also acceptable.Thus, banana peels are potentially used as raw material for processed food to provide functional health effects.
Banana peels can be considered as pudding ingredient due to their pectin content.Pectin may have an essential role as a thickening agent in pudding.It can also improve puddings' consistency, texture, rheological behavior, and sensory characteristics [28].High pectin content is generally present in yellow banana peels or ripe bananas.The pectin content varies depending on its variety, which ranges from 1.92 to 3.25%.Previous studies reported that the pectin content of Kepok peel and Ambon peel was 19% and 12.98%, respectively [7,8].
This research aimed to investigate the effect of banana peel addition on the physicochemical characteristics and sensory perception of pudding.This study made four different pudding formulations based on banana variety (Ambon and Kepok) and banana peel concentration (3 and 6% of total formulation).Puddings were then analyzed for moisture and dietary fiber content, hardness, color, syneresis, and acceptability.The products resulting from this study are expected to achieve good health and well-being as one of the Sustainable Development Goals (SDGs).

The making of pudding with banana peel
The banana peels were initially washed, soaked with salt, and boiled for 5 minutes to clean the peels from remaining pesticides.The cleaned banana peels were blended with 100 mL mineral water, filtered, and poured into the saucepan.Sugar, mocaf flour, carrageenan, and powdered milk were added and cooked until the mixture was boiled.The pudding mixture was then poured into cups and refrigerated until the gel was set.Pudding formulations made in this study can be seen in Table 1.

Dietary fiber analysis
The analysis of dietary fiber content was carried out by Saraswanti Indo Genetech (SIG) with the method suggested by AOAC.Initially, the fat was extracted using the Soxhlet extraction method using hexane for 6 hours.A total of 0.5 g of sample was taken and placed into Erlenmeyer.As much as 25 mL of 0.08 M phosphate buffer and 0.05 mL of termamyl enzyme were added to the Erlenmeyer.The solution was incubated with a shaking water bath at 95 o C for 30 minutes.After cooling, the solution was added with 5 mL of protease enzyme and incubated with a shaking water bath at 60 o C for 30 minutes.The solution was then cooled and added with 5 mL of 0.325 N HCl and 0.15 mL of amyloglucosidase enzyme and incubated for 30 minutes.Then 140 mL of 95% ethanol was added at 60 o C for 60 minutes.The solution was filtered using Whatman filter paper.The filter results were washed with 2x10 mL 78% ethanol, 2x10 mL 95% ethanol, and 2x10 mL acetone.After washing, the filter paper with its residue was placed in an aluminum cup and dried in an oven at 105 o C for 12 hours.After drying, the results were cooled in a desiccator and were then weighed [10].

Hardness analysis
A texture analyzer (Shimadzu SM-20N-168) was used to evaluate sample hardness.As many as 50 g of pudding with 4.9 cm diameter and 2.8 cm height was analyzed at a speed of 1 mm/sec at room temperature.All results were depicted with a time-force graph [11].

Color analysis
Products' color was analyzed by measuring the value of L*(0 for black and 100 for white), a* (negative for green and positive for red), and b* (negative for blue and positive for yellow) using a colorimeter.

Syneresis test
Syneresis was evaluated by storing the pudding at chiller temperature and observed for 24, 48, and 72 hours.Each sample was placed in a cup to collect the water released by the pudding during storage.Syneresis was calculated by comparing the initial weight with the weight lost during storage [12].

Sensory evaluation
Fifty untrained panelists were participated in this study.The first step of sensory evaluation was hedonic test using 9-point scale (1 = "extremely dislike" and 9 = "extremely like") to assess the overall acceptance of the product.After that, the panelists were asked to assess their perception towards pudding's attributes using 5-point JAR (Just About Right) scale (1 = "too weak", 3 = "just about right", and 5 = "too strong").The sensory attributes evaluated in JAR analysis were lightness, banana aroma, milk aroma, sweetness, and hardness.

Optimum treatment determination using De Garmo effectiveness index
In this study, the parameters included into calculation were moisture content, dietary fiber content, texture, color, syneresis, and overall liking due to the presence of significant result among treatments.Score of 0-1 was given to each parameter based on its' importance, then calculate the weigh value (treatment score/ total weigh).The effectiveness value was obtained by dividing [treatment value -worst value] with [best value -worst value].After that, product value was calculated by multiplying weigh value and effectiveness value.Product with the highest value indicated the optimum treatment.

Data Analysis
The data analysis on physicochemical and acceptance level was performed statistically using One-Way ANOVA (Analysis of Variance) followed by a Post-hoc Tukey's test if there were significant differences using SPSS software (IBM 25, USA) with a significance level of 0.05.The JAR data was analyzed using the penalty feature on XLSTAT Sensory (Lumivero, version 2023.1.2.(1406)).

Physicochemical properties of pudding with banana peel addition
Table 2 delivers the moisture content of all samples.Increased banana peel concentration showed no effect on puddings' moisture content compared to the control.This finding followed the previous study by Proverawati et al. [13], which reported no significant difference in the moisture content of steamed cake with Kepok banana peel compared to the control.On the contrary, Eshak [14] reported increased moisture content in balady flat bread after adding banana peel.This contradictive result was possibly due to different banana varieties.Kepok and Ambon peels used in this study also showed no statistical differences in the moisture content of the puddings.This result was proposed due to the similar amount of moisture content found in Ambon (42.14%) and Kepok (45.99%) [27].This study showed that banana peel addition with different types and concentrations significantly increased the dietary fiber content of the pudding when compared to control (Table 2).The addition of Ambon peel resulted in the higher dietary fiber content than that of Kepok peel.Increased banana peel concentration only resulted in increased dietary fiber of the pudding with Ambon peel.This finding was supported by Proverawati et al. [13] reported that Ambon peel had originally higher dietary fiber content (12.02%) than Kepok (10.44%).Previous study from Alshehry [15] reported a significant increased on dietary fiber of the biscuit with banana peel (ranged from 5.72 -14.19 g) when compared to control (3.65 g).A similar result also found in the used of banana peel powder incorporation into Egyptian balady flat bread.Product with powdered banana peel had 2.18% fiber content while the control was 1.42% [14].
The hardness of pudding with banana peel addition could be seen at Table 2.The statistical analysis results showed that the addition of banana peels with different types and concentration had significant difference on texture of the pudding.Pudding with 6% Ambon peel addition (A6) had the highest hardness value, while the hardness of other formulations was statistically similar (K3) and lower (A3 and K6) than control.The texture characteristics of pudding with the addition of banana peels are formed by the amount of pectin in its composition.Besides of pectin, the addition of sugar also affects the texture of the pudding.According to Ellis et al. [16], sugar addition will affect the microstructure of an agar fluid gel which affect the formation of gel.The texture of the pudding is influenced by gel strength, which is influenced by pectin.
Pectin is known as good water binder.Thus, higher pectin content in food composition may result in denser product.Therefore, based the assumption of increased pectin content, the pudding with banana peel addition and its increased concentration should have more rigid texture compared to the control.However, in this study the results were inconsistent, in which A6 was significantly higher than the control, while A3, K3, and K6 were lower than the control.This was probably due to the filtering process which separated the remaining banana peel particles after being mashed.This step may result in nonoptimal pectin content of banana peels.Research conducted by Hartati [17] utilized banana peels in donuts production.The results showed that the more banana peels used, the harder the donuts produced.Another study by Wirawan and Sudiarta [18] reported a thick-textured jam with banana peels addition.
Adding banana peels with different varieties and concentrations significantly decreased pudding lightness compared to the control (Table 2).Compared to the Kepok variety, the Ambon peel addition produced a significantly darker pudding.Pudding with 6% Ambon peel (A6) was the darkest among samples.The darker color of the pudding with banana peel addition was presumably due to the presence of polyphenolic compounds in banana peels that may lead to enzymatic browning reactions.This reaction develops a dark brown color by producing a quinone substance.Bananas rapidly undergo enzymatic browning after exposure to oxygen due to the disruption of fruit tissue during cutting.The heating process also affected the products' lightness (L*), redness (a*), and yellowness (b*) through non-enzymatic browning, namely the Maillard reaction and caramelization.Maillard reaction is a reaction between reducing sugars and amino acids in the presence of heating, while caramelization occurs due to degraded sugar.The formation of caramel could lead to the brown color of the product, increasing the redness and yellowness values [19].
Syneresis is an extraction of liquid from a gel that occurs due to slow gel contraction and is affected by time.The greater syneresis value in pudding is not preferred by the consumers [26].In this study, banana peel addition successfully decreased syneresis when compared to control (Table 2).Each formulation used kappa carrageenan for gelling formation.Control had the highest syneresis due the gel on kappa carrageenan could break easily; thus, other ingredients, such as pectin, must be added to form an elastic gel [20].Pectin is a fiber that binds water and disrupt milk components such as protein.The protein stability will prevent and hold water movement to reduce the syneresis [21].In other words, the results obtained were in accordance with the theory and it was proposed due to the pectin content in banana peel.
Comparing the banana variety used in this study, the syneresis was found to be lower in pudding with Ambon peel than that of Kepok.This result was underlying by the higher pectin content in Kepok (19%) [7] than Ambon (12.98%) [8].The syneresis was also found to be lower in the product with higher banana peel addition.The addition of 6% Kepok peel performed the lowest syneresis among samples.This finding corroborates previous study reported that incorporating banana peels in yogurt made from camel milk resulted lower syneresis than control [22].The syneresis value of yogurt with the addition of banana peels ranged from 25.1 -28.2%, while the control was 30.74%.

Sensory evaluation of pudding with banana peel addition
Penalty analysis can be used to evaluate decreased liking corelated with non-optimal sensory attributes.The JAR penalty analysis of pudding with the addition of banana peels can be seen in Table 3. Note: Pudding with the addition of 0% (control), 3% (A3 and K3), and 6% (A6 and K6) banana peel (Ambon = A; Kepok = K).F (%) = frequency (%); P/P = penalties/p-value; TW = too weak; JAR = Just About Right; TS = too strong; OL = overall liking.Number in bold indicate significance at alpha 5%.The control had the lowest overall liking (5.58), while the A6 sample had the highest (7.14).This finding proved that banana peel addition significantly affected the increased overall liking of the pudding.The pudding with 6% Ambon peel was perceived as the sample with significantly highest overall acceptance among samples.
Figure 1-5 shows the mean drop analysis for each sample.In these figures, red and green bars indicate significant and no significant differences at alpha 5%, respectively.However, the gray bar indicates the test was not counted due to insufficient cases (<20% frequency).The pudding's lightness significantly affected the overall liking of control, A6, and K6 (Table 3).Based on the mean drop results, it is necessary to decrease the lightness of control (Figure 1) and increase the lightness of A6 (Figure 2) and K6 (Figure 3).This was due to the lightness attribute significantly decreasing the overall liking if it was considered too weak or too strong.Adding banana peels resulted in a darker color due to polyphenols in banana peels, which facilitates the enzymatic browning reaction [19].The banana aroma only significantly affected the overall liking of the K6 (Table 3).The K6 sample significantly decreased overall liking when the banana aroma was too strong (Figure 3).Thus, reducing the intensity of the banana aroma in K6 sample is necessary.Amyl acetate, amyl butyrate, and acetaldehyde contribute to the banana aroma found only in fully ripe bananas.Among those volatiles, amyl acetate is the main compound of the unique banana aroma.Amyl acetate content is considerably higher in Kepok, resulting in a more robust aroma than Ambon [23].Thus, a dominant banana aroma was found in the pudding with a higher concentration of Kepok peel.
The banana aroma was perceived as "enough" and had no effect on the overall liking of A3, A6, and K3 (Table 3).No significant mean drops for both "not enough" and "too much" was observed in A6 (Figure 2) and A3 (Figure 4); however, K3 interestingly had a significant mean drop for too much aroma (Figure 5).This finding indicated that several consumers significantly disliked the "too much" banana aroma of K3.However, this segment can be ignored due to a higher portion of consumers considering the banana aroma of this sample as JAR.
The milk aroma significantly affected the overall liking of samples A6 and K6 (Table 3).Based on the mean drops analysis, the A6 sample should reduce the milk aroma intensity (Figure 2).The K6 needed no improvements since the aroma had already been considered as JAR (Figure 3), and any reformulation made in this sample should result in no change in milk aroma.In this study, the amount of milk added to all formulations was the same.However, there was a perception that the milk aroma was too strong in sample A6.This was presumable due to the acetoin compound contained in Ambon peel.Acetoin is an aromatic compound in the Cavendish banana species, to which Ambon belongs [24].Acetoin gives a creamy and butter-like aroma, widely used in milk and cream production [25].The presence of acetoin was the proposed reason for the increased perception of the milk aroma on A6.The attributes of sweetness and hardness had absolutely no effect on overall liking (Table 3).There is no need for improvement for these attributes in all samples.Based on the National Standard of Indonesia (SNI), pudding with the addition of banana peels has met the standards.This was in accordance with the criteria for pudding, which is semisolid, has a normal smell, taste, and color, and has a chewy texture (referred to SNI 01-3552-1994 regarding jelly agar).

Optimum formulation of pudding with banana peel addition
Analysis of De Garmo effectiveness index was performed to determine the optimum pudding formulation based on physicochemical and sensory data.Pudding with 6% Ambon peel addition (A6) had the highest product value (Table 4), indicating the best performance among samples.This formulation had 88.76% moisture content, 5.57% dietary fiber, 1.29 N hardness, 2.5% syneresis value, and 7.14 hedonic score (perceived as like by consumers).Note: Pudding with the addition of 0% (control), 3% (A3 and K3), and 6% (A6 and K6) banana peel (Ambon = A; Kepok = K).

Conclusion
The addition of different types and concentrations of banana peel showed a significant effect on the physicochemical and sensory properties of the pudding.Increased banana peels incorporation into pudding formulation increased dietary fiber, hardness, lightness, and sensory acceptance, but decreased syneresis.Pudding characteristics were also affected by banana variety.Ambon peel resulted in the higher dietary fiber content, hardness, and sensory acceptance, while Kepok peel was best in inhibiting syneresis and improving product lightness.In general, product acceptance was influenced by lightness, banana aroma, and milk aroma.The addition of 6% Ambon peel (A6) was found to be the best formulation with 88.76% moisture content, 5.57% fiber, 1.29 N hardness, 2.5% syneresis value, and 7.14 hedonic score.However, sample A6 needs some improvements by increasing the lightness and decreasing the milk aroma.

Table 3 .
JAR penalty analysis of pudding with banana peel addition

Table 4 .
De Garmo Effectiveness Index