Chemical Constituents (Proximate, Minerals, Bioactive Compounds) of Pea [ Pisum sativum (L.)] Shells

Background: Peas are preserved by freezing in pea processing industries because of seasonal limitations; there is a vast amount of pea peels as solid waste generated. Now days, the nutritional and techno-functional properties of by-products play an important role in the development of functional and enriched products in the food sector. The current study aim to analyze the nutrients content in pea shells. The result suggests pea shells can be used for value-addition in products and presence of antioxidant in pea shell powder indicates a better health effect if consumed. Methods: In this laboratory investigation during 2017-2018 peas were collected from market a single lot and analyzed for chemical constituents. In this connection, a fibrous coat of pea shells was separated, dried and prepared powder to perform nutritional analysis. Result: The study result indicates that pea shells have high nutritive value, e.g. protein (17.76%), total dietary fiber (21.04%), calcium (803.33 mg/100 g), iron (10.70 mg/100 g), potassium (1078.75 mg/100 g), magnesium (1029.55 mg/100 g) and bioactive compounds. Fresh pea shells have higher antioxidant activity (91%) compared to powder (86%). The total phenols, vitamin C and β -carotene strongly correlated with antioxidant activity. During the storage study, total phenols and antioxidant activity significantly decreased while on 90 days it was increased.


INTRODUCTION
The production of peas at the world level, India is the second producer (4 million tons/annum) after china, which contributed 22.9% (FAOSTAT 2019).In India pea (Pisum sativum) is growing as a vegetable in different states due to suitable climate zone (winter) and fulfilling the aim of human and animal feed consumption (Mmihailvoic et al. 2005).The peel of seed is not pea peel waste; the outer covering is considered as a waste.India's yearly generated more than 1 million tons of pea peel is discarded as waste or use an animal feed (Upasana and Vinay, 2018).Due to the seasonal and perishable nature of peas, their accessibility is short, which generates the demand for its preservation (Garg et al. 2014).Now a days, the nutritional and techno-functional properties of by-products (fruits and vegetables) play an important role in the development of functional and enriched products in the food sector because they are promising sources of functional and bioactive compounds (Sagar et al. 2018) and due to antioxidant and anti-germicide properties, traditionally used as a remedy to prevent various degenerative diseases.An alternative path for consumption of plants components (fiber-rich) are the value addition of food, dietary supplementation and fortification will not boost the nutritional status but provide health benefits to peoples (Kiran, 2017).Plant proteins, primarily originating from industrial by-products, have gained attention in recent researches and also more demand for pulses and cereals having phenols content.Drying is an essential method to preserve of agricultural products, reducing their bulk and ensuring better shelf life.Pea pods have a good amount of moisture, so its storage is difficult (Garg, 2015).Pea shells can be dehydrated without much quality deterioration and can be utilized a nutrient rich mix for product development.
Based on experiment we propose that pea by-products hold many biologically active compounds which attain value addition or supplementation of products for nutraceutical use.The present investigation aims to prepare pea shells powder, analyzed nutritional properties and develop valueadded products.

MATERIALS AND METHODS
This study was performed in 2018 in February at the Food and nutrition department, College of Home Science, CCS HAU, Hisar, Haryana.

Procurement of material
Fresh peas were obtained from the vegetable market, Hisar, Haryana, India in single lots.

Preparation of samples (Fig 1)
Fresh pea pods shelled and drenched under tap water to remove dirt and impurities.After that, pods were dipped in hot water (60C for 10 minutes) and outspread over filter paper sheets to drain excess water.Separated the layer manually, chopped finely (edible layer) and firstly dehydrated in shadow (12 hours) at ambient temperature, after that, oven drying (24 hours, 45C).The dried shells were ground to make a fine powder (sieve size 420 microns) and stored (22±2C) in air-tight plastic bags for the next step.

Nutritional evaluation of pea shells
Fresh pea shells and powder were analyzed for the nutrients content (samples were performed in triplicates).

Storage study
Pea shells powder were stored at room temperature (22±3C) for 90 days and analyzed moisture, total phenols, flavonoids and antioxidant activity.

Statistical analysis
Data analyzed by using standard statistical methods ANOVA (CRD) and interpretation presented through average and standard error.The significant (p<0.05)proved by C.D. value (Sheoran and Pannu 1999).

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%)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 W adhwa (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 W adhwa (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
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

Storage study of bioactive constituents in pea shells powder
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.

CONCLUSION
This study reveals peas shell is a superb source of nutrients similar to pea grains.This study highlights the scope that incorporation of pea shells for value addition in traditional recipes can be encouraging and popularizing in terms of boost up the level of nutrients (minerals, antioxidants, dietary fiber and protein).Present effects advocate that pea shells hold many biologically energetic materials that can be applied to reap the high cost and prepared value-added products for nutraceutical uses.The value-added products are developed by incorporating powder (pea shells) at the market or household levels, which solve the environmental problem and are an appropriate choice for fulfillments the nutritional demand of the country.Due to its high nutritional properties,

Fig 1 :
Fig 1: Procedure of preparation of pea shells powder.

Table 1 :
Nutrients composition of pea shells.

Table 4 :
Correlation of bioactive compounds in pea shell powder.

Table 3 :
Bioactive compounds in pea shells powder (0 to 90 days) during storage study.