Nutritional parameters of pea shells
The pea shells finding of proximate composition conferred in Table 1. Almost similar results regarding moisture content (88.47%) in pea shells were reported by Krimat et al., 2021
(87.79%) and Upasana et al., (2018)
reported lower moisture (83.41%) content. A higher and lesser amount of moisture in pea shells powder reported by Hanan et al., (2020)
(10%) in green pea pods. Protein content in present study reported 17.76 gm/100 gm, whereas a higher protein (19.79, 18.29 gm/100 gm) content in pea shells powder was recorded by Upasana et al., (2018)
, Rathore et al., (2021)
in chickpea and lower amount of protein content was noticed by Garg (2015)
(14.8%) and Hanan et al., (2020)
(11.99%) compared to present study. Almost similar results in appreciate to fats (0.43%) content were by Garg et al., (2015).
A higher fat content (1.34%) noticed in green pea peels by Fendri et al., 2016
(0.87%) and 3.88% Hanan et al., 2020.
Similar results of ash (5.04%) content reported by Garg (2015) (5.0%) and Upasana et al., 2018
(5.65%) in pea peel. A higher value noticed by Aparicio et al., 2010
(6.6 gm/100 gm) and another study addressed by Hanan et al., (2020)
reported lower amount of ash content 4.61% compared to present study. Crude fiber content (7.76%) in pea shells powder are close proximity (7.86%) reported by Garg (2015)
. The lower values for carbohydrates reported by Garg (2015)
(61.43%) than present investigation (65.11%) and a higher value reported by Hanan et al., 2020
(69.5%). Garg (2015)
reported 309.11 kcal/100 gm energy content, whereas 335.43 kcal/100 gm found in pea pod powder present study. On the contrary, Bakshi and Wadhwa (2013)
reported a higher concentration of albumin (59.3%) followed by glutelin (17.8%), globulin (15.6%) and prolamin (7.3%) when compared to present results. Lu et al., 2020
reported 3-5% (prolamin and glutelin) protein fractions. The dietary fibers with the amount, 21.04%, 17.03% and 4.01% total, insoluble and soluble content, respectively found in present study. Aparicio et al., (2010)
reported contradicting results with a high amount of dietary fiber content 58.6%, 54.4% and 4.2% respectively. Hanan et al., (2020)
found that insoluble and soluble content in pea pods powder was 25.04% and 11.08%. Rudra et al., (2020)
reported that the lesser amount of fiber content in plant sample due to exclusion of the parchment layer with the intention to gain non-disruptive fibrous materials. In the present study, calcium content was found 803.33 mg/100 gm in pea shells powder. Almost similar results reported 0.83 gm/100 gm calcium in pea pods powder by Garg (2015)
but a lower amount of calcium (0.77 gm/100 gm) and iron (1.20 mg/100 g) content in pea pods was revealed by Aparicio et al., (2010)
and Bakshi and Wadhwa, 2013
(0.39%). Inside the present investigation, potassium content discovered 1078.75 mg/100 gm in pea shells powder comparable to 1.03 gm/100 gm potassium content of pea pods reported by Aparicio et al., (2010)
and Bakshi and Wadhwa 2013
(0.80%). Pea shells powder had 1029.55, 47.37, 10.70, 3.28 and 0.59 mg/100 gm magnesium, sodium, iron, zinc and manganese content respectively. Aparicio et al., (2010)
reported a contradictory results of minerals i.e.
magnesium (0.21 gm/100 g), sodium (0.14 gm/100 g), iron, zinc and manganese as 1.20, 0.27 and 0.06 mg/100 g, respectively. Bakshi and Wadhwa (2013)
reported that the peas by-products containing minerals like magnesium (0.22%), sodium, Iron, zinc and manganese content were 189.0, 9.0, 27.58 and 18.4 (ppm) per 100 gm, respectively. Hanan et al., 2020
reported a lower amount (2.66 mg/100 gm) of iron in pea pods powder.
Bioactive compounds in pea shells
Table 1: Nutrients composition of pea shells.
From the existing investigation (Table 2) it was found that the quantity of total phenols in fresh and pea shells powder was 36.46 and 304.62 mg GAE/100 g, respectively which was higher compared to the values (62.5 mg/100 gm) noted by by Hadrich et al., (2014)
in dry pea pods. The concentration of phenols depends upon the kind of seeds variety. The flavonoids content was found to be 7.3 and 24.44 mg RE/100 gm in fresh and pea shells powder in existing experiments. Flavonoids amount in ethyle acetyate and methanol extraction were 22 and 3.5 mg QE/100 gm as reported by Hadrich et al., (2014)
. The antioxidant activity (FRAP) observed in present study was 133.33 and 1000.00 mgTE/100 gm in fresh pea shells and powder, respectively. The antioxidant activity (DPPH) was 2,595.69 and 2468.0 mg TE/100 gm in fresh pea shells and powder in present study. Hadrich et al., (2014)
reported 650 µg/ml (methanol) and 350 µg/ml (ethyl acetate) in extract of pea pods. The percent of inhibition (DPPH) was 91.05% in present study whereas; Ishaq et al
., (2015) reported 75% antioxidant activity and Jalilisafaryan et al., (2016)
found 91.03% antioxidant activity through DPPH in peas. On the contradicted results reported by Krimat et al., 2021
total phenolic content in fresh and powder in peas were 4.34 and 4.05 to 13.29 mgGAE/gDW and flavonoids content 2.91 and 2.74 to 5.76 mgQE/gDW respectively. The formation of Maillard reaction products may add antioxidant activity and interfere with the Folin-Ciocalteu, DPPH and FRAP test (Sousa et al., 2018). Hanan et al., 2020
reported carotenoids content 7.628 mg/100 gm but in present investigation fresh pea shells and powder reported 1.2 and 56.87 µg/100 gm. In the present investigation, vitamin C was found higher in fresh pea shells (35.9 mg/100 g) compared to pea shell powder (6.6 mg/100 g). Similarly, Srivastava and Jain 2019
reported that the ascorbic acid content was decreased in dried ker compared to fresh form. β-carotene in fresh pea shell and powder was recorded 387 and 2483.87 µg/100 gm. El-din et al., (2013)
reported that different fresh vegetables contain β-carotene (41.40 to 340.51 µg/100 gm) and vitamin C (33.83 to 92.65 mg/100 gm) in different range.
Storage study of bioactive constituents in pea shells powder
Table 2: Bioactive compounds in pea shells.
The storage study results of bioactive compounds depicted in Table 3 indicated a significant decrease (p<0.05) in total phenols in pea shells powder after 15 days to 60 days but significantly increased at 90 days. Similar results reported by Sonawane and Arya (2015)
in wood apple and jambhul and Syamaladevi et al., (2012)
in canned black and blue berries, the total phenols were significantly increased during storage. This change during storage due to chemical reaction or may be external factors (air, light and temperature) or moisture and cell destruction affected the stability of polyphenols. In the present investigation, the total flavonoids amount in pea shells powder was decreased significantly throughout storage periods. Sonawane and Arya 2015
noticed a simliar decreasing pattern of flavonoids content in wood apple and jambhul. Antioxidant capacity measured by FRAP found reduction during the storage period from 1001 to 959.28 mgTE/100 gm but at 90 days increasing pattern was noticed. The degradation of the amount of flavonids and total phenols in pea shells powder reduced the antioxidant capacity measured by FRAP. The antioxidant capacity measured by DPPH method shows a significant reduction but at 90 days it was significantly increased 2,199.62 mgTE/100 gm. Similarly result pattern was reported by Sonawane and Arya (2015)
in wood apple and jambhul. The moisture content was consistently increased in pea shells powder during the storage ranging from 3.89 to 5.02%. Breda et al., (2012)
reported a similar result during storage in guavira pulp powder. Moisture content influences shelf life during storage, excessive water supports the microbial growth increased leading to decreased shelf life. Total phenols, vitamin C and β-carotene strongly correlated with DPPH while poorly (weak) correlated with flavonoids (Table 4). β-carotene (0.95) and flavonoids (0.66) strongly correlated with FRAP while very poor correlated with total phenols (-0.33) and vitamin C (0.35) was noticed. No significant correlation was observed in this experiment.
Table 3: Bioactive compounds in pea shells powder (0 to 90 days) during storage study.
Table 4: Correlation of bioactive compounds in pea shell powder.