Chemical and Nutritional Evaluation of Banana Peels and Their Potential Use in Improving The Egyptian Balady Bread

Introduction

   Food production is increasingly seeking nutritious foods with health benefits (Coltro and Karaski, 2019). Fruit and vegetable peels are the main by-product of processing and are an excellent source of phytochemicals that have many beneficial effects on human health(Lario et al., 2004).

   Bananas are the second most produced fruit after citrus, accounting for 16% to 17% of total world production(Alzate et al., 2021). Banana, Musa genus, is one of the major fruit crops with high global economic value and ranks fifth in world trade (Wardhan et al., 2022). Bananas are economically rentable, but their consumption generates more than 26 million tons of dry matter residue annually worldwide, mainly due to the disposal of their peels(Ahmad and Danish, 2018; Coltro and Karaski, 2019 and Gomes et al., 2022).

  In 1987, efforts were initiated in Egypt to enhance banana production by introducing new banana germplasm varieties, specifically Grand Nain (Macusa cavendishii) and Williams hybrid (Mucosa accuminate).The results indicated that both species exhibited high yields and produced good-quality fruit (Abo-EL-Ez, 2017).According to the report by Sabin Nature ( 2022), banana production in Egypt reached 1.29 million tonnes. This represents a significant increase from 108,000 tonnes in 1972, with an average annual growth rate of 5.49%.

  However, one study has shown that the peel contains high levels of polyphenols, carotenoids, and other bioactive components that are beneficial to health(Zhang et al., 2005). However, one study has shown that the peel contains high levels of polyphenols, carotenoids, and other bioactive components that are beneficial to health(Gomes et al., 2022). This may be due to a lack of understanding of the benefits of business use.

   In addition to its excellent nutritional value, banana peels have a variety of health benefits, treating enteritis, diarrhea, dysentery, ulcerative colitis, nephritis, gout, heart disease, hypertension, and diabetes. Banana peels are also rich in phenolic compounds,with high antioxidant activity that prevent heart disease and cancer. Banana peels are rich in fiber, protein, crude fat, lipids, pectin, essential amino acids, polyunsaturated fatty acids, and micronutrients(Oguntoyinbo et al., 2021). Banana peel extracts contain more antioxidants, suggesting intensive peel us in foods and nutraceuticals. However, the chemical composition and physicochemical and functional qualities of banana peels determine their potential use (Zaini et al., 2022).

   Banana peel flour, like pulp flour, could be employed in new products with standardized compositions for a variety of industrial and household applications (Chen et al., 2020). Despite being an important source of numerous functionally essential bioactive chemicals, little scientific effort has yet been made to identify their usefulness in terms of food and nutraceutical applications. This biomaterial has the potential to provide novel products with standardized compositions for a variety of industrial and residential applications(Singh et al., 2016). Therefore, new economic strategies to reduce waste and post-harvest losses and increase the added value of this food crop should be evaluted (Petsakos et al., 2019).

   Therefore, the objective of this study is to evaluate the chemical and bioactive components of banana peels (musa sapientum) grown in Egypt during three ripening stages and to apply the sensory evaluation of a flat Egyptian bread formulation designed to produce value-added nutritious and functional products and reduce disease risk..

MATERIALS AND METHODS

Materials:

  Sixty Kg of Bananas (Musa sapientum) were collected from a distribution market in Alexandria-Egypt and were divided into 3 stages of ripening: Unripe (green), ripe (yellow) and after-ripening (AR).

Other ingredients used in the preparation of bread were flour (72%extraction), sugar, and leavening  from the local market .

Chemical and reagents:

 Chemicals and reagents were obtained from El-Gomhouria company, Alexandria, Egypt and Sigma Aldriech (Steinheim, Germany). All chemicals are analytical grade.

Preparation of banana peel powder:

The samples were thoroughly cleaned and the pulp and peel were separated. Peels were washed with distilled water and dried at 60°C for 48 h. in an air oven. The dry peels were ground to obtain a powder, packed in glass containers and frozen and stored at - 18°C until further analysis.

Methods:

Proximate chemical analysis:

  Initial moisture content, cured protein, crude Lipid, ash, and crude fiber were determined in banana peels at different stages of maturity following the methods described in the Association of Official Analytical Chemists (AOAC, 2005). The Nitrogen Free Extract was calculated according to the following formula;

NFE%=[100-(CP%+CL%+CF%+ASH%)]

Where: CP=Crude Protein, CL=Crude Lipid, CF=Crude Fiber.

Determination of total phenolics and flavonoid contents:

  The total phenolics content of banana peels was determined using a modified Folin-Ciocalteu colorimetric method described by Sakanaka et al. (2005). The total phenolics content of the three stages was expressed as mg gallic acid equivalent per gram from the calibration curve of gallic acid. Total flavonoid content was determined using a modified method by Sakanaka et al. (2005). Briefly, the measurement was compared to a preset standard curve of prepared Quercetin standard solution and expressed as mg of Quarecitin equivalents per 100 g of flour.

Determination of antioxidant activity:

Scavenging activity of DPPH radical:

  The determination of DPPH free radical scavenging activity of peel extract was determined as described by Ahmad, A. et al. (2015) based on a reaction with stable 1,1- diphenyl-2-picrylhydrazyl (DPPH) radical dissolved in absolute ethanol. The capacity to scavenge the DPPH radical was calculated using the following equation:

DPPH-scavenging effect (Inhibition%) =100x (A blank – A sample/ A blank).

Where A=Absorption.

Ferric reducing antioxidant power (FRAP) assay:

The reducing power of ethanolic extracts was determined according to the method cited by (Oyaizu, 1986),which involves the presence of antioxidants in extracts to reduce the ferricyanide complex to the ferrus form. Absorbance measurements were taken at 700 nm. Triplicate tubes were prepared for each extract increased absorbance of the reaction mixture indicated increased reducing power.

Determination of total carotenoids:

Total amount of carotenoids determined according to (Rangana, 1979) 15 g of peel powders plus 3g celite 454 (Tedia, Ohio, USA) were weighed. Successive extractions with 25mL acetone were done to obtain a paste which was transferred into a sintered funnel (5μm) coupled to a 250 mL Buchner flask and filtered under vacuum.The procedure was repeated several times until a colourless sample was obtained. The extract is then transferred to a 500 separatory funnel containing 40 ml petroleum ether. The aqueous phase was discarded. The extract was then transferred through a funnel to a 50mL volumetric flask containing 15g of anhydrous sodium sulfate. The volume was made up of petroleum other and the samples was examined  at 450 nm

The total carotenoid content was calculated using the following formula

Carotenoid content (μg/g) = =

where A = Absorbance

Total extract volume = V

P = sample weight

   = 2592 (B-carotene extinction coefficient in petroleum ether)

Preparation of bread using peel powder:

  Baladi bread was prepared according to the method described by (Segura-Badilla et al., 2022). Flatbread (72% extraction) with some of the flour replaced with banana peel flour (5%, 10%, 15%) (Eshak, 2016). The mixture consisted of 95,90,85 g flour, 2% compressed yeast dissolved in warm water (40°C), 3.5 g corn oil, 2 g salt, and 50-72 ml water.The flour and other ingredients were mixed and left at room temperature for 40 minutes to complete fermentation. The dough was cut into loaves and baked in an electric oven at 250°C for 3 minutes. It was then air cooled and packed in polyethylene bags until used for the required analysis and measurements.

Sensory evaluation:

  Ten trained penalties from staff and post-graduate students from Food Science Department.Fac.Agric-Saba Basha evaluated the bread color, flavor, texture and overall acceptability.Anine-point hedonic scale was used to rate the sensory properties where 9 is (Like extremely) and 1 (Dislike extremely). The ratings were then given numerical values (Amerine et al., 1965).

Statistical Analysis :

  All results were presented as means±Standard deviation (SD). Data was subjected to one-way analysis of Variance (ANOVA) using (SPSS/PC+) Version-22 Soft Ware Package. Means were further differentiated using Duncan's Multiple Range Test at p(Steel and Torrie, 1997)

Results and Discussion

Proximate chemical composition of banana peel at various stages of maturity

Table (1) presents the proximate chemical composition of the three stages of banana peel maturation. Results revealed significant changes in all tested parameters in the different stages.

     The moisture content of both unripe (green) peels and ripe (yellow) peels exhibited the highest moisture content which was significantly different compared to AR peels, being 90.20, 89.34 and 87.17 %, respectively. As a matter of fact, the water content plays an important role in determining the shelf-life of the product, as it is dependent on the genetic content of varieties as well as climatic conditions. In our study, it was obvious that the peels in all stages carry much water. The high moisture peel contents observed suggest that the peels requiring carbohydrates are the chief source of energy to the body. It was reported by Hausmann et al. ( 2016) that products with lower water content generally are less subjected to degradation by microorganisms and chemical changes. But generally speaking the moisture content in this study was similar to other varieties of banana peels. The crude protein content showed a significantly higher content in ripe (yellow) peels (8.72) than in unripe and AR stage Table (1). It is important to remark that fruits values of crude protein are low because fruits generally are not potential sources of proteins (Marles, 2017). On the other hand, Zaini et al.( 2022) reported that crude protein in banana varieties may range between 5.5 and 7.87 depending on diversity and genetic composition. Ahmed et al. (2016), reported that crude protein in yellow peels was 7.57%. Banana peel can be considered a good source of amino acids because most of the 18 amino acids (essential and non-essential amino acids) are present in banana peel at various levels of development (Khawan and Deka, 2016).

          The crude fat of all three stages ranged between 7.50% for ripe peels to 8.35%. for unripe. Both unripe (green) and ripe (yellow) stages exhibited the highest crude fat content with no significant differences between them being 8.35% and 8.22%, respectively and were significantly different than after the ripe stage (7.50%). Meanwhile, Ahmed et al. (2016) reported that crude fat in the powder peel of banana peel (yellow), was 10.44 which is higher than the recorded values in our study and lower than those of Anhwange et al. (2009). It was reported by Zaini et al. ( 2022). that crude fat in peels of different varieties ranges between 2.24% and 11.6%.

     Ash is the inorganic residue remaining after water and organic matter have been removed by heating. It was reported by Emaga et al. (2007) that the ash content in different banana peels varied from 6.4 to 12.8%. As can be seen, in Table (1) the highest ash content was observed in yellow dried peels at 17.79% which was significantly different from the green and ripe stages.

     Unripe (green) peels showed the highest crude fiber content (37.12%) compared to both the ripe (yellow) and AR stage. Green banana peels contained the highest crude fiber content (37.12%) and were significantly different than the yellow and ripe peels. On the other hand, Pyar and Peh (2018) reported that crude fiber banana peel may reach 19.2%. It was reported by Arun et al. (2017) that the soluble dietary fiber from Musa paradisiaca decreases cholesterol than the insoluble dietary fiber

  Considering carbohydrates measured as NFE, both yellow and unripe peels had the Lowest NFE with no significant differences between them, whereas, the after ripe stage, recorded the highest NFE content (40.90%).

Table (1) Proximate chemical composition of banana peel at various stages of maturity.

• The results are expressed as mean±standard deviation of triplicate analysis.
• Means within the same row of different letters are significantly different at (P < 0.05).
• *Calculated on a dry weight basis
• NFE= Nitrogen-free extract

Total phenolics, total flavonoids and carotenoids of banana peels at different stages of maturity

  As can be seen, the significant increase in the content of TP and TF is observed as the process of ripping progresses, reaching its maximum at banana peel after the ripe stage being 31.31 mg GAE/g and 5.63 mg/100ml, respectively.

Phenols are important secondary metabolites and are present at higher levels in banana peels than in other fruits. Numerous phenolic compounds are present in banana peels, including gallic acid, catechins, epicatechins, tannins, and anthocyanins(Sidu and Zafar, 2018). It has also been reported that the gallocatechin in banana peels is five times higher than in the pulp, proving that the peel is a treasure trove of antioxidants(Someya et al., 2002)

It was reported by Vu et al. (2018) that banana peels comprise more than 40 compounds identified as individual phenolics with a total content of 47mg of gallic acid equivalent (GAE/g dry matter). The phenolic compounds, found in banana peel can be further categorized into four subgroups, namely flavonols, hydroxycinnamic acids flavan-3-ols and catecholamines (Vu et al., 2018).

Results also revealed in Table (2) that the highest stage contained carotenoids in ripe yellow banana peel being 13.93 μg leutin / 100g and was significantly different than the unripe green peel and peel after the ripe stage being 8.21 and 10.99 μg leutin / 100g, respectively. Carotenoids have many beneficial effects on human health, including being precursors of vitamin A, antioxidants, anti-cancer, anti-obesity, and anabolism of bone components, (Vu et al., 2019).

Table (2): Total phenolics and total Flavonoids and carotenoids of banana peels at different stages of maturity

• The results are expressed as mean±standard deviation of triplicate analysis.
•   Means within the same row of different letters are significantly different at (P < 0.05).
• *QE;Quercetin Equivalent

Antioxidant activity of banana peels at different stages of maturity

  Table (3) represents the antioxidant activity of banana peels at the different stages as measured by DPPH% inhibition and FRAP.

Results revealed that as the ripening stage progresses the antioxidant activity significantly (P<0.05) increases reaching its maximum for banana peel after the ripe stage (89.66) compared to unripe (green) and ripe (yellow) stages (44.16 and 64.82%), respectively as measured by DPPH.

 The FRAP assay also showed a significant. activity as the maturation at the age of peels developed where the banana peels after the ripe stage showed high significant antioxidant activity (48.15 mg TE /g) as compared to both the unripe (green) and ripe (yellow) stage Table (3).

Antioxidant assays are used to evaluate the antioxidant capacity of banana peel extracts and fractions. It is essential to measure the ability of the chemical components of banana peel extracts to scavenge free radicals and prevent the formation of reactive oxygen species (ROS). High levels of ROS can cause abnormal signaling to cells, resulting in cell damage(Winterbourn, 2008)

     Multiple studies have linked (ROS) to chronic diseases such as neurodegeneration, cancer, diabetes, and inflammation(Mittal et al., 2014; Świętek et al., 2019). The phenolic compounds in banana peels are composed of a significant number of hydroxy groups, which may enhance their ability to scavenge reactive oxygen species(Świętek et al., 2019) It is worth noting that the high FRAP activity in the peel is attributed to phenols and carotenoids(Kreft et al., 2006).

Table (3): Antioxidant activity of banana peels at different stages of maturity

• The results are expressed as mean±standard deviation of triplicate analysis.
•   Means within the same row of different letters are significantly different at (P < 0.05).
• *TE: Trolox Equivalents

Sensory evaluation of Egyptian Balady bread substituted with different percentages of banana peel powder from the after ripe stage.

Table (4) shows the sensory evaluation of Egyptian Balady bread substituted with different percentages of banana peel powder from the AR stage.

     Interestingly, it was found that the flavour as tested by panelists was still accepted up to 15% substitution with a score of (6.50). As a matter of fact, both texture and colour were less scored by panelists as the level of substitution increased but was not rejected (up to 15%). As a matter of fact, the light brownish colour of the obtained powder did not affect the acceptability of colour by the panelists (Wohlt et al., 2009) That is why in our present study we have chosen 15% substitution level which gained the highest score in overall acceptability by panelists as compared to the control for further proximate chemical analysis to examine how much this substitution level will enhance both nutritional value of bread Moreover, also a high concentration of banana peel in the formula from AR stage may increase the phytochemical and antioxidant potency of the product.

Table ( 4  ): Sensory evaluation of Egyptian Balady bread with different concentrations of banana peels

• The results are expressed as mean±standard deviation of triplicate analysis.
• Mean values in a row with different letters are significantly different at p<0.05.

Proximate chemical composition of bread with added 15% banana peel from after ripe stage

   Table(5) demonstrate the proximate chemical composition of bread with  15% banana peel after the ripe stage as compared to control

     Bread is a staple food eaten daily. Because bread is made primarily from refined flour, it contains small amounts of dietary fiber, vitamins, minerals, and other phytochemicals that help prevent various diseases (Capurso and Capurso, 2020).

As presented in our results a significant increase was observed in protein, fat and ash content of substituted bread with 15% added after rippening banana peel powder compared to control .However, a significant decrease was observed in moisture, and carbohydrate content of the substituted bread. These results were similar to those of Eshak, (2016) when substituting Balady flatbread with 5 and 10%banana peel. Similar to our study,  a decrease in carbohydrate content was observed. Several studies have shown that carbohydrate restriction improves glycemic control, insulin resistance, and obesity (Yancy et al., 2005).

  Interestingly, a hugely significant increase was observed in total phenolic content revealing a huge impact on health promoting compounds reaching 139.75mg GAE/100g compared to 19.67 mg GAE/ 100g for control bread.

Thus it was stated by Agama et al. (2016) Banana peels have significantly higher amounts of ash, protein, fat, and fiber than pulp, making banana peel foods with excellent functional properties possible.

Table (5): Proximate chemical composition of Balady bread with 15%substitution with banana peel after the ripe stage.

• The results are expressed as mean±standard deviation of triplicate analysis.
• Means within the same row of different letters are significantly different at (P < 0.05).
• *Calculated on a dry weight basis

CONCLUSION

Banana peels showed an enhanced nutritional value and functional properties which can provide a new perspective for producers with regard to developing value added products. In our present study the corporation of banana peel in Balady bread significantly improved their nutritional value and provided essential antioxidant compounds for disease prevention.