Postharvest Properties of Unripe Bananas and the Potential of Producing Economic Nutritious Products

ABSTRACT

Fresh banana is highly perishable fruit; about 30% of the banana production is lost after harvest. There is a need for alternative uses for banana fruit to help reduce the post-harvest losses such as utilizing food product. Currently, banana fruit and flour are of interest due to their nutritional and antioxidant value. The objective of this study was to evaluate the banana fruit and flour physical, chemical and functional properties and incorporate it into food products. Mature green banana fruit from two varieties; ‘Williams’ and ‘Baradika’ were subjected to some ripening properties determination, the dried pulp then milled and sieved to obtain flour. The flour was subjected to physiochemical properties determinations. The flour was then incorporated with other ingredients to make baked and fried tortilla chips. The results revealed that the net weight of the dried sample (flour) was 30.5–38.1 and ash content was 3.20–2.1 for ‘Williams’ and ‘Baradika,’ respectively. The pasting properties of both flours were appropriate to be used in baked or fried products. The sensory properties of all prepared products were acceptable. While fried products were superior compared to baked ones, the differences within the cultivars were not significant. Total marketing costs of ‘Williams’ banana chips were EGP 2900/ ton, while it was about 8595 pounds/ton for tortilla chips. For ‘Baradika’ it recorded 2900 pounds/ton for banana chips and 6195 EGP/ton for tortilla chips. Hence, postharvest loss of banana fruit can be reduced by utilizing them in food products.

KEYWORDS:

• Banana fruit
• flour
• physiochemical properties
• fried and baked chips

Introduction

Banana is one of the most traded food crops (eight^th) in the world and the fourth most important food crop in the developing countries (FAO, 2013). It is grown in more than 150 countries throughout the tropics and subtropics; these countries export about 67% of its banana production mostly to the USA and European countries (FAO, 2007). Banana is the most consumed fruit in the tropical region and is considered for them the main source of carbohydrate. Banana is known for its health benefits for humans as it is packed with nutrients such as potassium, calcium and iron. It is also containing carbohydrate, fat, protein, fiber, and vitamins (Ahwange et al., 2009; Seth et al., 2014).

In Egypt, roughly 1, 341, 478 tons of bananas are produced in 2016 from about 27.632 thousand hectares, the total area of banana cultivation (FAO, 2016). There are commercial and local banana varieties grown in Egypt. Commercially, two types of bananas; Grand Nain and Giant Cavendish, such as ‘Williams.’ On the other side several local varieties, which have low-quality attributes and mostly used as windbreaks for banana plantations and their fruit are either wasted or sold for a cheap price, such as ‘Baradika’ are also there.

Export bananas are harvested mature green, shipped to the export countries, and there it is artificially ripened in special rooms with ethylene gas, to trigger. The ethylene treatment is used to provide uniform ripened banana fruit before marketing. Banana fruit ripening stage is a transition period between maturity and senescence. The fleshy banana fruit ripens from the inside out, which means that the pulp starts to ripen before the peel and leads to several changes such as peel color in only 3–4 days, and then fruit loses its marketability (Salvador et al., 2007). Significant losses of banana production have been recorded (35%) for many reasons: poor handling from the farm to the market, inappropriate transportation and storage of this perishable fruit (Jahanbakhshi et al., 2019a). A great loss also occurs when growers decided not to harvest the whole plantation due to ample production and saturated market. Therefore, reducing these losses through proper postharvest technologies using mature green bananas, instead of sending them all to the market after ripening with ethylene treatment, could be a solution for this problem and may add significant commercial value to the fresh fruit.

Banana is not only eaten fresh but also could be used as an additive in different food products or incorporated in various functional foods. In the tropic, it is very popular using many of Musa species such as plantain (starchy banana) for chips making (Adeniji and Tenkouano, 2007). Dessert banana fruit, especially the mature green one, possess high contents of resistant starch, dietary fiber and phenolic acids that have health benefits for humans (Champ et al., 2003). The resistance starch is the resistance to digest type of starch that acts like a soluble fibers and linked to various benefits for human health includes lower blood sugar levels, reduced appetite, and for digestion and cause a prebiotic effect (Fuentes-Zaragoza et al., 2011). Thus, its incorporation of banana flour in various functional foods is of interest (Sarawong et al., 2014; Yangılar, 2015).

Previous research reported that bananas’ pulp can be dried and the flour has been prepared (Mohapatra et al., 2010). Therefore, green banana flour is recently used in food products such as slowly digestible cookies, high-fiber bread symbiotic, fermented milk, ice cream and yogurt formulation (Batista et al., 2017; Yangılar, 2015).

Due to its valuable nutritional components such as fiber, protein, minerals and antioxidant compounds, banana fruit could be used as a value-added supplement and will be a great nutritional constitute in the human diet. Banana fruit and flour supplements may be able to improve the nutritional status of many foods.

This study investigated the potential of reducing the postharvest losses in banana production by utilizing part of the commercial and local produced bananas into food processing to produce healthy and nutritious snacks. This study will highlight some of the characteristics of the ‘Baradika’ fruit that benefit the growers, add value to local farmers’ products and help raise their income. The economic efficiency of using tow banana varieties in the manufacture of healthy and nutritious snacks compared to the traditional ones found in the Egyptian market.

Materials and Methods

Plant Materials Preparation

Mature green banana fruit about (75% green) of commercial variety ‘Williams’ and local variety ‘Baradika’ were obtained from a local plantation in southern Egypt. Fruit were separated from the hand and washed with bleach, rinsed three times with distilled water then patted dry. The uniform group of green banana fruit was subjected to physical and chemical measurements as well as cooking quality determination. Other group of fruit was peeled, and their pulps were sliced (circular about 2 mm thickness), soaked in 2% citric acid solution for 10 min to avoid browning. Part of the banana slices went into frying, and the other part of the slices was dried; using a Forced-Air oven dryer at 60°C for 48 hours, it is then milled with a hammer mill and sieved using a 250 microns mesh sieve to obtain a fine flour. The banana flour was packed in an airtight polyethylene bags, stored at refrigerator at 5°C for subsequent use.

Physical and Chemical Characteristics of the Banana Fruit

‘Williams’ and ‘Baradika’ banana fruit were subjected to some measurements to determine their ripening properties. Fruit length, fruit weight, pulp/peel weight ratio, fruit thickness was also measured using a digital caliper. Total soluble solids (TSS) of the pulp juice were measured using a digital refractometer (Jahanbakhshi, et al., 2019b). Titratable acidity and pH of the juice were also determined (Dadzie and Orchard, 1997).

Cooking Quality

Cooking quality evaluation was done according to a method of pulp (Baoxiu et al., 2000). Fruit were washed and peeled pulp weight was recorded as initial weight. The pulp samples were put in a beaker containing boiling distilled water at 93°C. Samples were allowed to boil at different time intervals of 5, 10, 15 and 20 min. After boiling for the specified time intervals, samples were emptied on a sieve to drain the boiling water. The samples were cooled for 10 min at room temperature before weighing to get the final weight. Pulp weight change was calculated after each time interval by subtracting the initial weight from the final one.

Chemical Properties of the Banana Flour

Moisture content, crude protein, ash, crude fat, total starch and total fiber of banana flour were determined according to the official methods of (AOAC, 2000) in triplicates (Suntharalingam and Ravindran, 1993).

Physical Properties of the Banana Flour

Color Analysis

The color of the banana flour was measured with a Hunter Lab (Model D25color and color difference Meter). This color assessment system is based on Hunter L, a and b coordinates and was represented as: ‘L’ is the lightness and darkness of the color, ‘a’ is the degree of redness or greenness and ‘b’ is the amount of yellowness or blueness with white tile of Hunter Lab color standard (L = 92.56, a = −0.87 and b = −0.15).

Bulk Density

The ratio of the mass of the particle to the volume of the particle of the banana flour, excluding open and closed pores.

Rehydration Characteristics

Water absorption index (WAI) was measured according to a method of (Becker et al., 2014). In a centrifuge tube, a sample of 2 g from the banana flour was mixed with 25 ml of water, heated for 30 min in a water bath at 30^◦C, the solution was centrifuged at 3000 rps for 10 min. The supernatant was placed in a Petri dish and dried at 90^◦C for 4 h to obtain a dry solid weight, and the wet sediment was weighed.

The WAI was determined as follows:

$\mathrm{W}\mathrm{A}\mathrm{I}=\frac{Weightofthewetsediment(g)}{Weightofthedrysample(g)}x100$

The supernatant resulting from the WAI is weighed (M1), then kept into hot air oven at 105°C for 4 hrs until constant weight is obtained to dry. Samples were left to cool in desiccators then weighed (M2). The solubility of the flour percentage was measured by (M2/M1) % according to (Becker et al., 2014).

Swelling power (SP) defines the capacity of the particles of the flour to hold water and can be calculated in (g/g) as follows:

$\mathrm{S}\mathrm{P}(\mathrm{g}/\mathrm{g})=\left[\mathrm{W}3/\left(\mathrm{W}1\times \left(100-\mathrm{S}\mathrm{o}lub\mathrm{i}\mathrm{l}\mathrm{i}\mathrm{t}\mathrm{y}\right)\right)\right]\times 100$

W1 is the weight of the flour sample, W2 is the dried weight of supernatant (g) and W3 is the weight of sediment paste.

Pasting Properties of Banana Flour

The pasting properties of the flour suspensions (14%, moisture basis) were analyzed as viscoelastic properties of the prepared gelatinized banana flour using RapidVisco Analyzer-4, Newborn Scientific, Australia. The sample turned into slurry by mixing 3 g of the sample with 25 ml of water inside the RVA can. The can was inserted into the tower, which was then lowered into the system. The slurry was heated from 50°C to 95°C and cooled back to 50°C within 14 min. Parameters estimated were peak, trough, final, breakdown and setback viscosities, pasting temperature, and time to reach peak viscosity (Newport Scientific, 1998; AACC, 2000).

Preparation of Snacks

Banana Chips

The prepared slices were patted dry and salted before frying. The slices were deep-fried in vegetable oil at 170ºC for 2–3 min using an electrical fryer to get chips. The resulted golden chips were dried, cooled to room temperature and stored in sachets at room temperature.

Tortilla Chips

Two snacks (backed and fried tortilla chips) were made from different composite blends using standard ingredient formulations as shown in Table 1.

Table 1. Formula and ingredients of backed and fried tortilla chips

	Quantity (g)
Ingredients	Baked tortilla	Fried tortilla
Dried banana flour	20	20
Flour of dry corn	5	5
Minced ras cheese	4	–
Baking powder	1	1
Corn starch	2.5	2.5
Vegetable oil	1	–
Onion powder	–	1
Garlic powder	–	1
Salt	0.25	0.25
Water	20–25 ml	20–25 ml

Sensory Evaluation

The sensory attributes (color, odor, texture, taste, crispness, general appreciation) of fried chips and tortilla chips made from ‘William’ and ‘Baradika’ pulp and flour were carried out using the procedure described by (Sauvageot, 1989). Thirty panelists (male and female) aged 19–40 years old were asked to evaluate the sensory attributes of all products and give a score out of 10 (Iwe, 2002). The collected data then were analyzed.

Statistical Analysis

Data were analyzed using one-way ANOVA in the PROC GLM procedure of Statistical Analysis System (SAS version 9.2 for Windows, SAS Institute Inc., Cary, NC, USA) (SAS® 2009). To compare the characteristics of the fruit and flour produced by the two studied cultivars; ‘William and Baradika.’ Mean comparisons were then performed using Duncan Multiple Range test to determine the significant differences at P ≤ 0.05 within the products in the sensory analysis indexes between each cultivar.

Results and Discussion

Physical and Chemical Characteristics of the Banana Fruit

In the present study, two varieties of banana; ‘Williams’ and ‘Baradika, grown in southern Egypt were evaluated for the fruit characteristics, as an indication of the fruit-ripening stage, and the potential of utilizing these bananas for food processing. Random uniform unripe banana fruit were subjected to some physical and chemical measurements such as length, weight, thickness of the fruit and pulp/peel weight ratio, as well as titratable acidity and pH and TSS of the pulp juice. Table 2 shows that ‘Williams’ fruit were superior (roughly three times) for the fruit length and fruit, pulp, and peel weight as compared to ‘Baradika’ that had smaller fruit, while no difference in fruit, pulp, peel thickness between them as the ‘Baradika’ fruit was short and wide. Consumers often prefer thicker and bulkier banana fruit (Dadzie and Orchard, 1997; Muchui et al., 2010), the characteristics of the local variety ‘Baradika’ indicates why this type of banana is commercially neglected in Egypt and do not receive adequate agricultural treatments by the growers.

Table 2. Physical characteristics of the banana fruit

Variety	Fruit weight (g)	Pulp weight (g)	Peel weight (g)		Fruit thickness (cm)		Pulp/peel ratio (cm)	Pulp thickness (cm)	Peel thickness (cm)	Fruit length (cm)
Williams	95.09 ± 0.81*	56.43 ± 0.62*	37.80 ± 0.33*		2.90 ± 0.03		1.49 ± 0.02	2.62 ± 0.04	0.28 ± 0.02	13.1 ± 0.07*
Baradika	30.21 ± 0.53	17.20 ± 0.23	12.74 ± 0.0.31		2.43 ± 0.04		1.37 ± 0.03	1.92 ± 0.02	0.51 ± 0.02*	9.30 ± 0.08
Cooking quality of the banana fruit
	Pulp weight (g)						Pulp weight change (%)
Variety	Before cooking	5 min cooking	10 min	15 min	20 min		5 min	10 min	15 min	20 min
Williams	56.6 ± 0.43	59.2 ± 0.50	60.9 ± 0.61	62.4 ± 0.57	62.8 ± 0.56		4.5 ± 0.07	7.7 ± 0.08	10.2 ± 0.11	12.0 ± 0.13
Baradika	18.0 ± 0.13	19.7 ± 0.12	21.4 ± 0.16	21.8 ± 0.13	22.1 ± 0.14		9.1 ± 0.08*	18.2 ± 0.11*	21.0 ± 0.17*	22.3 ± 0.22*

*Means that the differences are significant between the two varieties at (P ≤ 0.05).

Pulp/peel weight ratio has been used as an indication of the fruit-ripening stage as it increases as the fruit ripens from 1.1–1.3 at the green stage to 2.7 at the ripening stage (Muchui et al., 2010). Pulp/peel ratio was found 1.49–1.37 for Williams and Baradika, respectively, which means that the fruit at the mature green stage (Table 2). This also indicates that the fruit of the two varieties had more pulp weight than peel weight. Thus, the potential to use the pulp of both varieties to produce larger sized slices for processing into various products such as chips, or dried flour for baking, is possible.

The Cooking Quality of the Banana Fruit

The cooking quality of the investigated banana varieties is presented in Table 2. Data in Table 2 revealed that after boiling of banana pulp for various periods of time 5, 10, 15 and 20 min, there was a significant increase in the banana pulp weight, and tissue softening. The amount of water absorbed during cooking was depending on the duration of cooking and the varieties. For ‘Williams’ variety, the increase in pulp weight was 4.5, 7.5, 10.1, 11.7%, while ‘Baradika’ recorded 9.1, 18.2, 21.0, 22.3% after 5, 10, 15 and 20 min cooking, respectively. This indicates that ‘Baradika’ absorbed significantly more water during cooking and consequently lost less firmness as compared to ‘Williams.’ This significant difference in fruit weight change and firmness loss may be due to differences in fresh pulp weight and cell size, structure and chemical composition of tissue components such as starch. The softening in fruit tissues as a result of cooking was found to be due to a loss of cell turgor and series chemical changes in the polysaccharide matrix, along with starch swelling and gelatinization in banana compared to plantain (Baoxiu et al., 2000). Although fruit pulp weight was higher in ‘Williams’ than ‘Baradika,’ ‘Baradika’ pulp absorbed more water and increased in weight (Table 2). The pulp tissue was able to stay coherent after even boiling for 15 min for ‘Baradika’ and only 10 min in ‘Williams,’ this might be due to the pulp cell structure and polysaccharide matrix, along with starch composition. These results showed that the fruit physical and cooking quality investigations provide information about the suitability of the banana fruit for processing.

Chemical Properties of Banana Fruit and Flour

Chemical analysis for the fruit and dry samples (flour) was done for both varieties and presented in Table 3. The fruit juice pH and the titratable acidity for the two varieties were (5.63, 5.70) and (0.34, 0.35), respectively, these values are in the normal range for the fresh fruit if harvested mature green. The change in titratable acidity and pH of banana fruit is one of the main indexes of ripening. Taste is mainly a balance between sugar and acid contents which makes acid determination important in the evaluation of fruit postharvest taste and quality (Muchui et al., 2010; Sakyi-Dawson et al., 2008). The TSS percentage of the banana fruit of ‘William’ and ‘Baradika’ was very low (4.9–5.3), which means that the fruit are in the mature stage (Table 3). The lower TSS of unripe banana flour is expected at the mature stage as the amylase, glycosidase, phosphorylase, sucrose synthase and invertase enzyme action lead to degradation of starch and the formation of soluble sugars (Muchui et al., 2010).

Table 3. Chemical properties of the banana fruit and flour

Tests	Williams	Baradika
Fruit
TSS	4.90 ± 0.05	5.30 ± 0.04
pH	5.63 ± 0.12	5.70 ± 0.09
TA	0.34 ± 0.02	0.35 ± 0.03
Moisture	70.50 ± 0.83*	62.30 ± 0.63
Flour
Ash	3.20 ± 0.03*	2.10 ± 0.03
Protein	5.40 ± 0.05*	2.96 ± 0.04
Crud fat	3.57 ± 0.07	4.12 ± 0.05
Total fiber	1.52 ± 0.04	1.59 ± 0.03
Total starch	68.55 ± 1.1	73.12 ± 0.92*
Minerals contents of the flour
Nutrients (mg/100 g)	Williams	Baradika
Fe	13.2 ± 0.32	12.6 ± 0.42
Na	300 .0 ± 1.22	433.0 ± 1.43*
P	20.7 ± 0.53*	13.3 ± 0.41
Ca	83.2 ± 0.76*	71.8 ± 0.80
K	1424.0 ± 1.70*	1253.0 ± 1.81

*Means that the differences are significant between the two varieties at (P ≤ 0.05).

Table 3 also presented the main flour composition of ‘Williams’ and ‘Baradika’ such as the moisture, protein, ash, crude fat, total fiber and total starch contents. After drying the pulp samples, moisture percentage was found higher in ‘Williams’ samples (70.5) compared to ‘Baradika’ ones (62.3), which means that the net weight of the dried sample (flour) is roughly 30.5–38.1 for ‘Williams’ and ‘Baradika,’ respectively. This flour of unripe banana of ‘Williams’ variety had almost the double protein percentage of Baradika’s (5.40–2.96). These data agreed with previous reports that banana protein depending on genome type, variety and climate (Elkhalifa et al., 2014). ‘Williams’ flour contains 3.57% fat content while ‘Baradika’ had 4.12%. The percentage of total fiber of both varieties was almost similar (1.52, 1.59). This substantial amount of fiber adds value to the banana flour as it contained dietary fiber that has health benefits (Emaga et al., 2008). Flour gave 3.20–2.1 ash for ‘Williams’ and ‘Baradika.’ A range of ash content for bananas was fewer than those previously reported by Zebib et al. (2015).

Starch breakdown into sugar is the major chemical change that occurs throughout the growth and ripening of banana fruit (Sakyi-Dawson et al., 2008). In mature green bananas, carbohydrate content is about 20–25% of the pulp weight mainly as starch (Dadzie and Orchard, 1997). The starch percentage was significantly lower in ‘Williams’ (68.55) flour compared to ‘Baradika’ (73.12%). Despite that it is still a high starch yield and is considered the major storage form of carbohydrates in both varieties compared to previous reported records for banana (Kudachikar et al., 2004). Banana flour starch and general composition are contributed to the quality of the flour and affect the functional performance such as pasting and gelling behavior compared to regular flour from other sources (Peroni et al., 2006). These properties of banana flour make it suitable to be a valuable ingredient in baking products or an additive in different functional foods.

The composition of the most important minerals of the banana flour is presented in Table 3. Potassium is known to be the most abundant mineral present in the edible portion of banana. Potassium content was 1424.0 and 1253.2 mg/100 g ‘Williams’ and ‘Baradika,’ respectively. Calcium content was 83.19–71.75 mg/100 g, and sodium content was 300 and 433 mg/100 g, while the content of phosphorus, was 20.56,13.27 mg/100 g for ‘Williams’ and ‘Baradika.’ Amount of iron was substantially good and almost same amount was found in both varieties (12.6 mg/100 g). The variation in mineral contents is mainly attributed to preferential absorbance of the plant cultivar and/or soil, climate, agricultural practice and the quality of water for irrigation (Rop et al., 2010). Minerals are very crucial in many plant growth and development aspects such as enzyme activities, free radicals attack protection, glucose homeostasis regulation (Ahwange et al., 2009). Due to its nutritive value, banana flour can be accompanied with other food products and add value to the final product (Ruales et al., 1990).

Physical Characteristics of the Banana Flour

Change in color of the banana is the major visible changes with the approach of maturation. Several studies have revealed that change in fruit color is an important indicator to identify stage of crop maturity physically (Muchui et al., 2010). Banana flour color of the two varieties used is measured and expressed with these terms (L*, a*, b*), and presented in Table 5. L* value of the banana flour showed that ‘Baradika’ flour was white/yellowish with the highest value of L* (42.6) and ‘Williams’ flour was somewhat dark yellow with a low value of L* (37.30). While both banana flour were more yellow with b* (14.16 and 11.93) and was not red with a* 2.05–2.22 (Table 4). The increase in the degree of lightness and yellowness in ‘Baradika’ might be attributed to starch contents (73.12%) and could be associated with its mature stage as compared to ‘Williams’ (68.55%). During the ripening of banana, the flesh color changes from unclear white for the product with a high starch content to a very soft yellow as the yellowing of the skin intensifies and the degree of lightness and yellowness increased in the cooking variety comparing to banana variety due to the starch contents (Salvador et al., 2007).

Table 4. Physical characteristics and pasting properties of Williams and Baradika banana flour

					Color
Variety	Bulk density (gm/ml)	Water AI %	Solubility %	Swelling power %	L	a	b
Williams	0.78 ± 0.02	300.0 ± 0.58*	0.28 ± 0.04	3.0 ± 0.06	37.3 ± 0.49	2.22 ± 0.02	11.93 ± 0.33
Baradika	0.89 ± 0.04	274.6 ± 0.053	0.36 ± 0.03	2.7 ± 0.06	42.6 ± 0.53*	2.05 ± 0.02	14.16 ± 0.36*
	Pasting properties
Variety	Peak viscosity (RVU)	Trough viscosity (RVU)	Breakdown viscosity (RVU	Final viscosity (RVU)	Setback viscosity (RVU)	Paste time (Min.)	Pasting temperature (^◦C)
Williams	2050 ± 2.1	1874 ± 1.73	176 ± 0.88	2960 ± 3.11	1086 ± 1.87	6.93 ± 0.07	84.20 ± 0.69
Baradika	4218 ± 2.53*	2695 ± 2.0*	1523 ± 1.9*	3784 ± 3.31*	1089 ± 1.98	5.27 ± 0.08	79.10 ± 0.88

*Means that the differences are significant between the two varieties at (P ≤ 0.05).

Table 5. Sensory evaluation of the prepared banana products from ‘Williams’ and ‘Baradika’ banana. Each value is the mean of 30 replications (n = 30)

	Fried slices		Fried tortilla chips		Baked tortilla chips
Sensory attributes	Williams	Baradika	Williams	Baradika	Williams	Baradika
Odor	8.2 ± 0.03 a	8.7 ± 0.04 a	7.9 ± 0.02 b	7.7 ± 0.03 b	7.2 ± 0.02 bc	6.8 ± 0.03 c
Texture	7.6 ± 0.04 b	8.8 ± 0.02 a	8.5 ± 0.05 a	8.3 ± 0.04a	8.2 ± 0.04a	7.9 ± 0.03a
Taste	8.4 ± 0.05 a	9.1 ± 0.03 a	8.2 ± 0.04 ab	8.3 ± 0.05 ab	7.7 ± 0.03 b	6.8 ± 0.03 b
Color	9.5 ± 0.06 a	9.7 ± 0.05 a	7.8 ± 0.03 b	7.4 ± 0.02b	7.9 ± 0.02 b	6.7 ± 0.04 b
Crispiness	8.8 ± 0.03 a	9.0 ± 0.05 a	8.0 ± 0.03 b	8.2 ± 0.03 b	8.6 ± 0.05 a	7.6 ± 0.04 b
Acceptability	8.5 ± 0.04 a	9.0 ± 0.06 a	8.4 ± 0.02 a	8.1 ± 0.04 ab	8.3 ± 0.05 ab	7.4 ± 0.04 b

At each product, paired comparisons were made for all sensory attributes using “Duncan’s Multiple Range Test.” Different letters in each row indicate a significant difference at P ≤ 0.05.

Bulk density can be defined as the weight of a particle per the unit volume of this particle and is considered one of the main indexes of structural changes of the dried materials (Sreerama et al., 2009). Data in Table 4 showed that bulk density ranged between 0.78 for ‘Williams’ to 0.89 gm/ml for ‘Baradika,’ this was consistent with previous reports.

Rehydration characteristics such as water absorption index represent the ability of the product to associate with water under conditions where water is limiting and could be related to the physical state of starch the dietary fiber and protein in the flour (Waliszewski et al., 2003). WAI of banana flour was found to be decreased 300 for ‘Williams’ and 274.60 for ‘Baradika.’ The capacity of samples to hold water is expressed as swelling power, was 3.0–2.74%, while the solubility of the flour was 0.28–0.36% for ‘Williams’ and ‘Baradika’ (Table 4). WAI ability to bind more number water by polysaccharides as well as monosaccharides present in banana flour, it led to decreasing the solubility of the flour that affected the swilling power of the flour (Waliszewski et al., 2003). The difference in rehydration may be due to the physical state of starch, dietary fiber, and protein existing in the banana flour, which is high in water-holding capacity, and consequently enhancing the water absorption (Waliszewski et al., 2003).

Pasting Properties of Banana Flour

Pasting properties describe the conduct of starch and starch-based products during heat processing in the presence of water heating (Babu et al., 2014). The pasting characteristics of the banana flour are shown in Table 4. Peak viscosity which is the maximum viscosity developed during or soon after the range of 2050–4218 RVU for ‘Williams’ and ‘Baradika’ flour, respectively, which is higher than the range of previous literature (Babu et al., 2014). Final viscosity is also measured for the banana flour as it is an important parameter in predicting the textural quality and it is an indicator of the ability of the flour starch to form viscous paste or gel after cooking and cooling. The final viscosity measured was 2960 RVU for ‘Williams’ and 3784 RVU for ‘Baradika’ banana flour, and this might be attributed to high starch content in both flours. Higher peak and final viscosity at high temperatures of banana flour make it more suitable for application as thickeners in products such as sauces and other foods (De la Torre-gutierrez et al., 2008). The trough viscosity is known as holding strength or the ability of starch granules to remain undisrupted after a period of constant high temperature and mechanical shear stress, this hold period is often accompanied by a breakdown in viscosity. Trough viscosity of the banana flour was 1874–2695 RVU, and the breakdown viscosity was 176–1523 RVU for both banana flours (Table 4). ‘Baradika’ flour with more starch appears to have greater relative tendency to withstand high temperature and shear force during processing compared to ‘Williams’ flour, this was in agreement with previous reports that breakdown viscosity ranged between 115.42 and 487.92 RVU for different banana varieties and the highest value was for the starchy bananas (Daramola and Osanyinlusi, 2006).

The retro-gradation tendency of starch in the flour sample measured by setback viscosity was high and ranged from 1086 to 1089 RVU in both varieties (Table 4). The higher setback viscosity values of flour suggest a lower tendency for retrogradation. The setback value of banana flour was higher than those in early reported (Babu et al., 2014) who reported that value 778.66 RVU. Moreover, peak time, the time in minutes at which the peak viscosity occurred and measures the cooking time of the flour, is measured. Peak time of ‘Williams’ flour (6.93 min) was higher than ‘Baradika’ flour (5.27 min). Pasting temperature; the temperature at which the first detectable increase in viscosity due to swelling of starch is occur, is also detected. A high pasting temperature usually indicates that the flour has a high water absorption capacity (Julanti et al., 2015). The pasting temperature was 84°C to 79°C for both flours (Table 4).

Sensory Evaluation

The products’ sensory evaluation of the banana prepared by different processing methods from both varieties ‘Williams and ‘Baradika’ is presented in Table 5. As not expected, banana snacks are a new product for the Egyptian consumers and they have no background in the taste of such banana snacks, all products had got high score in the sensory evaluation. In general, all banana products (fried or baked) from both varieties were well accepted by all panelists despite the sexes or ages. The preference rating for odor, texture, taste, color, crispness and overall appearance was higher in ‘Baradika’ fried chips than all other products. There were no significant differences between the two varieties for the fried tortilla chips' sensory attributes. While fried products were superior compared to baked ones, the differences within the cultivars were not significant (Table 5). This was consistent with (Elkhalifa et al., 2014) who reported that fried-banana chips were desirable by the panelists and were more favorable over potato chips. However, deep fried-banana chips are usually high in fat contents that might affect consumers’ health, so that the low-fat chips were of recent interest. This type of chips can be obtained by baking instead of frying in oil, this method reduced the fat content of banana chips by 69% (Adeniji and Tenkouano, 2007; Elkhalifa et al., 2014; Ruales et al., 1990). The flour from mature green banana, which is rich in minerals, resistance starch, fiber and protein, was able to improve the nutritional contents when blended with cereal flour products. Results of green banana flour physical properties showed that this flour can successfully incorporate in a high percentage with other flour in baked products. Therefore, banana flour was incorporated with other ingredients to prepare baked tortilla chips. While baked tortilla chips from both flours were accepted as prepared, the color and taste scores were lower compared to fried chips and fried tortilla chips (Table 5). These baked products are healthier due to the lower fat content than fried ones. It can also be improved by adding more food flavors into the ingredients to enhance the taste or change the percentage of banana flour to improve the color.

The Economic Costs of the Banana Products

Production and marketing costs for the manufacture of a ton of banana fruit ‘Williams’ and ‘Baradika‘ in Qena Governorate: This section deals with the production and marketing costs of products manufactured from the Banana. These products consist of chips and tortilla chips. Table 6 shows that the costs of the marketing process (the product sells as a retailer) for Williams’ fruits which consist of collecting, sorting, grading, peeling, chopping, frying, drying, packing were 400, 900, 800, 500, 300 EGP/ton, respectively, representing about 5.97%, 13.43%, 11.94%, 7.46%, and 4.47%, respectively, of the total marketing costs of about EGP 2900/Per ton. While the total final costs reached to 6700 Egp/ton, and for the tortilla chips manufactured from ‘Williams’ bananas, the costs of the collection, sorting, grading, peeling, chopping, frying or drying, the cost of tortilla chips mix, packaging and transport vehicles were about 400, 900, 800, 5695, 500, 300 EGP/ton, respectively, representing 3.22%, 7.26%, 6.45%, 45.95%, 4.03% and 2.42%, respectively, of the total marketing costs of about 8595 pounds/ton, while the total final cost price of ton reached to 12395 EGP.

Table 6. Production and marketing costs of tons of banana products

	Williams banana variety				Baradika banana variety
	Chips		Tortilla		Chips		Tortilla
Costs	EP/ton	% of total final costs	EP/ton	% of total final costs	EP/ton	% of total final costs	EP/ton	% of total final costs
Production cost (price of banana crop)	3800	56.72	3800	30.66	1000	25.64	1000	13.90
Marketing cost
Collecting	400	5.97	400	3.22	400	10.25	400	5.56
Sorting, grading, peeling and chopping	900	13.43	900	7.26	900	23.10	900	12.50
Frying or drying	800	11.94	800	6.45	800	20.50	800	11.11
Mixing, baking and frying (for tortilla)			5695	45.95			3295	45.79
Packaging	500	7.46	500	4.03	500	12.80	500	6.95
Transporting	300	4.47	300	2.42	300	7.70	300	4.17
Total marketing cost	2900	43.28	8595	69.34	2900	74.36	6195	86.10
Total final cost	6700	100	12395	100	3900	100	7195	100

EGP = Egyptian pound

As for the costs of chips made from the ‘ Baradika‘banana were 400, 900, 800, 500, 300 EGP/ton, respectively, representing about 10.25%, 23.10%, 20.50%, 12.80%, 7.70%, respectively, of the total cost of about 2900 pounds/ton, but the total final cost of banana chips valued 3900 pounds/ton. While the tortilla chips made from ‘Baradika’ was 400, 900, 800, 3295, 500, 300 EGP/ton, respectively, and about 5.65%, 12.50%, 11.11%, 45.79%, 6.95%, 4.17%, respectively, of the total marketing costs of about EGP 6195/ton, but the total final cost of ton equal 7195 EGP.

Economic Efficiency and Profitability Indicators of Ton of Banana Chips and Tortilla Chips Made from (Williams’ and ‘Baradika’)

There are some economic indicators that can be used to estimate the economic performance of banana chips and tortilla chips production from both Williams’ and’ Baradika’ varieties. Those indicators include (net profit per ton; product incentive per ton and return on the expendable pound) that calculated as follows:

• Net profit per ton = (total revenue of ton – total final cost of ton)

• Product incentive = (net profit of ton/selling price of the farm of ton)×100

• Return on the expendable pound = (total revenue of ton/total final cost of ton)

Data in Table 7 showed that the total revenue of ton for both Williams’ and’ Baradika’ amounted to (10999 EP/ton and 11943.30 EP/ton) for chips, respectively. While it was (12776.50 EP/ton and 12665.40 EP/ton) for tortilla, respectively. It is calculated according to the traditional chips and tortilla chips prices in the Egyptian market that were nearly the same price for both products. Concerning Williams variety, the net profit per ton in the case of chips recorded 3399 EP but the tortilla chips recorded a small net profit that reached to 318.50 EP; at the same time, the product incentive of ton and the return on the expendable pound were 89.44 and 0.45, respectively for chips, while those values were also low for the tortilla chips and recorded 10.04% for the product incentive of ton and 0.03 for return on the expandable pound.

Table 7. Economic efficiency and profitability indicators of banana chips and tortilla chips made from (’Williams’ and ‘Baradika’)

	Banana (Williams)		Banana (Baradika)
Statement	Chips	Tortilla	Chips	Tortilla
Selling price of kilogram	55.55	55.55	55.55	55.55
Produced amount of product (kg)	198	230	215	228
Total revenue of ton	10999	12776.5	11943.3	12665.4
Total final cost of ton	7600	12395	3900	7195
Net profit per ton = (total revenue – total final cost)	3399	318.5	8043.3	5470.4
Product incentive per ton = (Net profit per ton/Selling price of ton of banana crop) × 100	89.44	10.04	804.33	547.04
Return on the expendable pound = (Net profit per ton/Total final cost of ton)	0.45	0.03	2.06	0.76

Source: Collected and calculated from the data of the field study in Qena Governorate for the study 2018.

The results mean that to manufacture one ton of Williams’ banana to tortilla chips and selling them as the same price as the traditional tortilla chips it will be not economical, but once the product is sold at least twice the traditional price of the tortilla chips it will enhance all the economic indicators of that variety, high net profit per ton of Williams’ banana can be achieved economically and practically because the nutritional value of the tortilla chips made from banana flour can be accepted by the consumer to buy twice the price of the traditional tortilla at least. The results of ‘Baradika’ in the same table followed different trends than that for Williams, the net profit per ton for chips was 8043.30 and for tortilla was 5470.40, while the product incentive of ton calculated (804.33 and 547.04) and return on the expendable pound reached to (2.06 and 0.76) for chips and tortilla chips, respectively. All values were positive for both chips and tortilla chips and these products can be manufactured from ‘Baradika’ and can achieve a clear economic profit.

From the results mentioned above, it is clear that the economic efficiency indicators of ‘Baradika’ variety were higher than that for Williams. At the same time, both banana varieties can be efficiently used in snacks production that is not known and not famous to the Egyptian consumers.

Of all of the mentioned above, harvesting loss can be reduced in the two studied banana cultivars by manufacturing snack products that are not known by the Egyptian market with sensory properties and higher nutritional value than the traditional types in the Egyptian market.

Conclusion

Two locally produced banana varieties can go through processing instead of ripening to be consumed fresh. These varieties were manufactured to banana chips or converted into banana flour with substantial contents of carbohydrates and minerals in addition to other manufacturing properties such as color, viscosity and gelatinization temperature. This flour was used to make tortilla chips with acceptable sensory properties as well as economic return. This may add value to local farmers’ production of these varities to raise their incomes.

Acknowledgments

The authors are very grateful to College of Agriculture, South Valley University, Egypt, for supporting this project financially. A great acknowledgment also goes to the National research center, Food Industry and Nutrition research division, Giza, Egypt, for providing pasting properties analysis of the banana flour.

Disclosure Statement

The authors are declining that there is no conflict of interest.

Additional information

Funding

This project is funded by South Valley University, Qena, Egypt.