The results of the percentage ripening of the plantain fingers under different ripening conditions are presented in Table 1. The number of days it took for ripening to occur ranged from 10 to 33 days. The results obtained showed that RP1 had the highest percentage of ripening as it took 19 days to ripen completely. Similarly, RP4 and RP5 completely ripened within 20 days. The least percentage of ripening was obtained from RP3 (33 days). It might be possible that during water storage, their climacteric phase was not initiated due to the restricted gaseous exchange. Also, blockage of intercellular spaces with water might have affected the O2 tension of the fruit tissue, resulting in the suppression of their ripening. High intake of water might also have reduced the gaseous contents of fruit rather than affecting their concentrations. Splitting was observed in RP3 which was undoubtedly attributed to the excessive intake of water. This effect might be due to the influx of water into the plantain fruit to maintain equilibrium between the water and water vapour pressure deficit of the fruit (Ullah, 2006; Pierre et al., 2016). Pierre at al. (2016) reported both splitting of plantain and slower ripening during storage under high humidity conditions.
Functional Properties of Plantain Flour Samples under different Ripening Conditions
The functional properties of plantain under different ripening conditions are presented in Table 2. The bulk density of ripe plantain samples ranged from 0.70 to 0.79 g/g with UPc (0.70 g/g) followed by RP3 having (0.71 g/g) and RP5 having the highest value (0.79 g/g). The control sample (UPC) had a bulk density of 0.70 g/g meaning that ripening increase bulk density. There was a significant difference in the mean bulk density at p ≤ 0.05 across the samples. Water absorption capacity (WAC) of ripe plantain samples ranged between 1.47 g/ml to 2.33 g/ml with RP1 having the least value (1.47 g/ml) and RP3 having the highest value (2.33 g/ml) when compared to UPC which had a water absorption capacity of 2.33 g/ml. WAC flour shows the ability of flour to absorb and bind water in a mixture (Giami and Alu, 1994). There was a significant difference in the mean water absorption capacity at p ≤ 0.05 among the samples. This result aligns with 2.00 and 2.50 g/ml reported by Onwuka and Onwwuka, (2007) and Kumalasari et al., 2020. These higher values in unripe plantain flour samples are associated with a higher starch content in the unripe plantain flour whose complex molecule will demand more water during hydrolysis than sugar molecules (Ihekoronye and Ngoddy 1985; Gbadamosi and Oladeji, 2013).
Table 2
Functional Properties of Plantain Flour Samples (Musa paradisiaca) under different Ripening Conditions
Properties | RP1 | RP2 | RP3 | RP4 | RP5 | UPC |
Bulk Density (g/g) | 0.75 ± 0.00a | 0.76 ± 0.01a | 0.71 ± 0.00b | 0.79 ± 0.01a | 0.79 ± 0.00a | 0.70 ± 0.01b |
WAC (g/ml) | 1.47 ± 0.42c | 1.50 ± 0.50c | 2.33 ± 1.53a | 2.13 ± 0.51b | 1.97 ± 0.21b | 2.33 ± 0.29a |
OAC (g/ml) | 1.03 ± 0.25d | 1.61 ± 0.25b | 2.05 ± 0.51a | 1.64 ± 0.10b | 1.58 ± 0.23b | 1.44 ± 0.48c |
Foaming capacity (%) | 9.48 ± 5.40c | 25.49 ± 5.19b | 10.13 ± 3.16c | 30.72 ± 5.99a | 33.99 ± 6.89a | 24.18 ± 6.30b |
Foaming stability (%) | 90.59 ± 4.35c | 89.18 ± 6.00e | 97.38 ± 2.59a | 94.06 ± 2.28b | 91.02 ± 1.37c | 88.51 ± 3.44d |
Emulsion capacity (%) | 46.66 ± 0.86b | 48.96 ± 3.23b | 45.71 ± 0.50c | 48.55 ± 1.34b | 50.54 ± 0.71a | 47.14 ± 0.40b |
Wettability (s) | 41.33 ± 10.07e | 66.00 ± 9.54d | 68.00 ± 10.54c | 30.67 ± 6.11f | 83.33 ± 6.11b | 161.00 ± 5.57a |
Solubility (%) | 37.67 ± 1.53b | 41.00 ± 4.58a | 10.67 ± 0.58f | 15.00 ± 0.00c | 16.33 ± 0.58c | 11.33 ± 0.58d |
Swelling index (%) | 12.62 ± 0.36b | 13.70 ± 0.85a | 8.29 ± 0.10c | 8.06 ± 0.04c | 8.18 ± 0.06c | 7.55 ± 0.19d |
Values are means of triplicate determination (± SD). Mean values with same alphabets on same row have no significant difference (p ≤ 0.05). |
KEY |
RP1 - Plantain stored on shelf |
RP2 - Plantain wrapped in foil |
RP3 - Plantain immersed in water |
RP4 - Plantain immersed in 5% salt solution |
RP5 - Plantain immersed in 6% salt solution |
UPC - Unripe plantain |
The oil absorption capacity of ripe plantain samples ranged from 1.03 to 2.05 g/ml with RP1 having the least value (1.03 g/ml) and RP3 having the highest value (2.05 g/ml) as compared to UPC which had an oil absorption capacity of 1.44 g/ml. There was a significant difference in the mean oil absorption capacity of the samples at p ≤ 0.05. Emulsification capacity of the ripe plantain flour samples ranged from 45.71–50.54%. RP3 had the lowest value (48.96%) while RP5 had the highest value (50.54%) as compared to the UPC which had an emulsification capacity of 47.14%. There was a significant difference at p ≤ 0.05 among the samples. The swelling indexes of the ripe plantain samples under different ripening conditions ranged from 8.06 to 13.70% with RP4 having the least value and RP2 having the highest value (13.70%) as compared to UPC which had a swelling index of 7.55%. High OAC and emulsion capacity values in flour are very useful for products that require emulsions and creaming properties (Onwuka, 2005). The results from this study showed a high WAC and swelling index so it can be recommended for bakery and pastry products.
The foaming capacity of ripe plantain samples ranged from 9.48 to 33.99%. RP1 had the least value (9.48%) while RP5 had the highest value (33.99%) as compared to UPC which had a foam capacity of 24.18%. The values were significantly different at p ≤ 0.05. Foam stability of the ripe plantain flour samples ranged from 89.18 to 97.38% with RP2 having the least value and RP3 having the highest value (97.38%). The formation of a stable foam is very essential in the preparation of several traditional cowpea-based food products in Nigeria and that the foam ability of a product is related to the rate of decrease of the surface tension of air/water interface caused by the absorption of protein molecules (Mepba et al., 2007; Kiin-Kabari et al., 2015). The wettability of the ripe plantain flour samples ranged from 30.67s to 83.33s. RP4 had the least value (30.67s) while RP5 had the highest value (83.33s) as compared to the UPC which had a wettability of 161s. There was a significant difference in the mean wettability of all ripe plantain samples at p ≤ 0.05. The wettability was lower in the ripe plantain samples than the unripe plantain samples because of the heavier weight of the ripe plantain flour samples which made them sink faster.
Proximate Composition of Plantain Flour Samples ( Musa paradisiaca) under different Ripening Conditions
The results of the proximate composition of the plantain flour samples under different ripening conditions are presented in Table 3. The moisture content of the ripened plantain flour samples ranged from 3.33 to 6.00% with RP1 having the least value (3.33%) and RP2 recorded the highest value (6.00%) and all the samples differ significantly (p ≤ 0.05). Also, sample UPC moisture content (6.67%) was significantly higher than the ripe plantain flour. The decrease in moisture content due to ripening followed the same trend with the report of Onwuka and Onwuka (2005), who observed that the moisture content of plantain flour samples decreased with ripening. The report found out that ripe plantain flour samples had the least moisture content (36.96%) and unripe plantain flour samples had the highest moisture content (61.62%). The moisture content of foods or its processed products gives an indication of its freshness and shelf life, and high moisture content of flour (> 14%) subjects it to increased microbial spoilage and short shelf life, which can lead to its deterioration (Adepoju and Adeniji, 2008; Oladeji et al, 2016).
Table 3
Proximate and Oxalate composition of Plantain Flour Samples under different Ripening Conditions
Composition | RP1 | RP2 | RP3 | RP4 | RP5 | UPC |
Moisture (%) | 3.33 ± 1.15e | 6.00 ± 0.00b | 6.00 ± 2.00b | 4.67 ± 0.58d | 5.33 ± 0.58c | 6.67 ± 1.15a |
Ash (%) | 3.00 ± 0.00b | 3.00 ± 1.00b | 1.33 ± 0.58d | 4.67 ± 1.53a | 4.67 ± 1.53a | 2.33 ± 0.58c |
Fat (%) | 9.17 ± 0.35a | 8.60 ± 0.36b | 5.00 ± 0.00c | 4.27 ± 0.25d | 3.00 ± 0.00e | 4.50 ± 0.00d |
Fibre (%) | 4.77 ± 0.25a | 3.00 ± 0.50c | 3.77 ± 0.25b | 3.50 ± 0.50b | 2.00 ± 0.00d | 2.77 ± 0.25d |
Protein (%) | 6.57 ± 0.44a | 5.25 ± 1.75b | 2.19 ± 0.44d | 3.51 ± 0.88c | 3.51 ± 0.88c | 3.94 ± 0.44c |
Carbohydrate (%) | 73.17 ± 0.73d | 74.15 ± 3.20d | 81.71 ± 2.89a | 79.39 ± 2.14c | 81.49 ± 1.63a | 80.03 ± 1.94b |
Energy value (kcal/g) | 389.00 ± 25.68b | 395.00 ± 3.50a | 380.60 ± 10.61c | 370.00 ± 3.04e | 367.00 ± 4.00e | 376.37 ± 6.00d |
Oxalate (100mg/g) | 11.34 ± 0.54e | 15.40 ± 0.70d | 20.34 ± 1.36c | 20.70 ± 1.12c | 22.86 ± 1.36b | 36.06 ± 2.07a |
Values are means of triplicate determination (± SD). Mean values with same alphabets on same row have no significant difference (p ≤ 0.05). |
KEY |
RP1 - Plantain stored on shelf |
RP2 - Plantain wrapped in foil |
RP3 - Plantain immersed in water |
RP4 - Plantain immersed in 5% salt solution |
RP5 - Plantain immersed in 6% salt solution |
UPC - Unripe plantain |
The ash content of the unripe and ripe plantain flour samples ranged from 1.33 to 4.67% with RP3 having the least value (1.33%), then RP4 and RP5 having the highest value (4.67%). This result aligns with the report of Egbebi and Bademosi (2011) which showed that ash content of ripe plantain flour is higher than that of unripe plantain flour. The reason for RP4 and RP5 having higher ash content could be because it absorbed salt from the storage media. The fat content of plantain flour samples ranged from 3.00 to 9.17%. RP5 had the lowest fat content (3.00%) while RP1 had the highest fat content (9.17%) as compared to UPC which had a fat content of 4.50%. There was a significant difference in the mean fat content of the samples at p ≤ 0.05. The fibre content of the plantain flour samples ranged from 2.00 to 4.77%. RP5 had the least fibre content (2.00%) while RP1 had the highest fibre content (4.77%). Unripe plantain flour sample (UPC) had a fibre content of 2.77%. There was a significant difference in the mean fibre content of the samples at p ≤ 0.05 and in agreement with the findings of Egbebi and Bademosi (2011).
The protein content of the samples ranged from 2.19–6.57% where RP3 had the lowest protein content (2.19%) and RP1 had the highest protein content (6.57%) among all the samples. The protein content of RP1, RP2 and RP3 were significantly different, but not significantly different between UPc, RP4 and RP5 (p ≤ 0.05). Protein is an essential component of diet needed for survival of animals and human beings. Their main function in nutrition is to supply adequate amounts of amino acids (Pugalenthi et al., 2004). Its deficiency causes retardation, muscle twisting, oedema, abnormal swelling of the body and collection of fluid in the body (Ayoola and Adeyeye, 2009; Aseidu, 1989; Oladeji et al., 2016). Ayoola and Adeyeye, (2009) observed an increase in crude protein content of plantain pulp during ripening and attributed such increase to the conversion of enzymes and/or protein synthesis. The carbohydrate values ranged from 73.17 to 81.71% with RP1 having the lowest value (73.17%) and RP3 having the highest value (81.71%). The carbohydrate obtained in this study is higher than the values reported earlier for boiled plantain (Frey, 2021), but agrees with the report of Onwuka and Onwuka (2005) that ripe and unripe plantain have dissimilar carbohydrate contents and that there is a significant difference (P ≤ 0.05). The energy content of the plantain samples ranged from 367.00 to 395.00 kcal/g with RP5 having the least value (367.00 kcal/g) and RP2 having the highest value (395.00 kcal/g). There was a significant difference in the mean energy content at p ≤ 0.05 among the samples.
Oxalate composition of plantain flour samples
The oxalate composition of plantain subjected to different ripening conditions as shown in Table 3 revealed that ripe plantain contains varying amounts of oxalate ranging from 11.34 to 22.86 mg/100g with RP1 having the least value (11.34 mg/100g) and RP5 having the highest value (22.86 mg/100g). There was a significant difference in the oxalate content at p ≤ 0.05 across all samples. There is clear indication that ripening cause a significant reduction in the oxalate content of plantain as unripe plantain (sample UPc) recorded 36.06 mg/100g oxalate content. This could be attributed to the biochemical changes that occur during ripening. This report is in agreement with earlier findings of Ayodele et al (2019) who reported a decrease in oxalate content of plantain due to ripening from 32.33 to 30.27 mg/100g. High amounts of oxalate inhibit the absorption of calcium into the body and cause kidney stone, the effect which can be neutralized by heating (Savage and Dubois, 2006). Another approach of reducing the adverse effect of oxalate is the Oxalobacter formigenes activity which depletes oxalic acid, by inducing oxalate excretion in the colonic zone of the intestine (Ivanovski and Drüeke, 2013).
Mineral Composition of Plantain Flour Samples ( Musa paradisiaca ) under different Ripening Conditions
Table 4 below shows the mineral composition of Plantain (Musa paradisiaca) under different ripening conditions. Iron (Fe) content of all the plantain flour samples ranged from 9.23 to 10.94 ppm with UPc having the highest value (10.94 ppm). There was a significant difference at p ≤ 0.05 among the samples. Fe was higher in the plantain samples immersed in salt solutions (10.85 ± 0.12ppm and 10.65 ± 0.01 ppm for RP4 and RP5 respectively). Zinc (Zn) in ripe plantain flour samples ranged from 0.81 to 1.64 ppm with RP2 having the least value (0.81ppm) and RP5 having the highest value (1.64 ppm) as compared to UPC which had a Zn content of 1.48 ppm. There was a significant difference at p ≤ 0.05 among the samples. Calcium (Ca) in ripe plantain flour samples ranged from 1.17 to 9.05 ppm with RP2 having the least value (1.17 ppm) and RP1 having the highest value (9.05 ppm). There was a significant difference at p ≤ 0.05 among the samples. The reason for RP1 having the highest Ca content could be because it had the least oxalate content and others were lower because of the high amount of oxalate which inhibits the presence of Ca. Calcium is very important in the formation of strong bones and teeth, for growth, blood clotting, heart function and cell metabolism (Roth and Townsend, 2003; Rolfes et al., 2009).
Table 4
Mineral Composition of Plantain Flour Samples (Musa paradisiaca) under different Ripening Conditions
Composition | RP1 | RP2 | RP3 | RP4 | RP5 | UPC |
Na (ppm) | 391.00 ± 0.00e | 448.00 ± 0.00c | 366.00 ± 0.00f | 905.00 ± 0.00a | 902.00 ± 4.00b | 407.50 ± 0.50d |
Mn (ppm) | 0.09 ± 0.01a | 0.07 ± 0.00b | 0.05 ± 0.01b | 0.09 ± 0.01a | 0.04 ± 0.01b | 0.14 ± 0.00a |
Mg (ppm) | 7.17 ± 0.01a | 7.11 ± 0.01b | 7.14 ± 0.01a | 7.07 ± 0.01b | 7.04 ± 0.00c | 7.12 ± 0.02a |
K (ppm) | 314.50 ± 18.50c | 242.00 ± 9.00f | 333.00 ± 55.00b | 276.00 ± 12.00d | 255.50 ± 5.50e | 359.00 ± 11.00a |
Fe (ppm) | 9.23 ± 0.03c | 9.50 ± 0.02c | 9.38 ± 0.01c | 10.85 ± 0.12a | 10.94 ± 0.01a | 10.65 ± 0.05b |
Zn (ppm) | 1.38 ± 0.01c | 0.81 ± 0.02d | 1.29 ± 0.03c | 1.43 ± 0.02b | 1.64 ± 0.01a | 1.48 ± 0.00b |
Ca (ppm) | 9.05 ± 0.02a | 1.17 ± 0.12f | 5.32 ± 0.18b | 3.55 ± 0.62d | 3.00 ± 0.03e | 4.86 ± 0.78c |
Values are means of triplicate determination (± SD). Mean values with same alphabets on same row have no significant difference (p ≤ 0.05). |
KEY |
RP1 - Plantain stored on shelf |
RP2 - Plantain wrapped in foil |
RP3 - Plantain immersed in water |
RP4 - Plantain immersed in 5% salt solution |
RP5 - Plantain immersed in 6% salt solution |
UPC - Unripe plantain |
Sodium (Na) content of the ripe plantain samples ranged from 366.00 to 905.00 ppm with RP3 having the lowest value and RP4 having the highest value. There was a significant difference at p < 0.05 among the samples. The RP4 and RP5 samples had very high Sodium content of 905.00 ppm and 902.00 ppm respectively which may be due to their immersion in salt solution. Manganese (Mn) content of ripe plantain samples ranged from 0.04 to 0.09 ppm with RP and RP4 with the highest value of 0.09 ppm. The value obtained for UPc (0.14 ppm) was higher than the ripe plantain flour samples suggesting that ripening reduce manganese content. Manganese is a micronutrient that functions as an enzymatic catalyst and co-factor in the synthesis of fatty acids and glycoproteins (Shomar, 2012). Magnesium (Mg) content of the ripe plantain flour samples ranged from 7.04 to 7.17ppm with RP5 having the least value (7.04ppm) and RP1 having the highest value (7.17ppm). There was a significant difference at p ≤ 0.05 among the samples. Potassium (K) in ripe plantain flour samples ranged from 242.00 to 333.00ppm with RP2 having the least value (242.00 ppm) and RP3 having the highest value (333.00ppm), while UPC had K content of 359.00 ppm.