In this study, 90 plant species of 67 genera belonging to 40 families were collected as edible plants from selected sites at Hamirpur district, Himachal Pradesh. Vegetation composition was distributed in various life forms; of which 30 species are as trees (35.3%, 25 native and five exotic), 11 shrubs (12.9%, six native and five exotic), 31 herbs (33.0%, 13 native and 18 exotic) and remaining 18 as creepers (18.8%, 14 native and four exotic). However, significant numbers of the recorded edible plant species were herbs, followed by trees (the most dominant life form). In contrast, other growth forms of the plant-like shrubs and creepers were sparsely distributed.
Of the total plant species, the maximum was found from family Moraceae (11) followed by Cucurbitaceae (8), Fabaceae (6), Amaranthaceae, Dioscoreaceae, and Rosaceae (5 each); whereas, 14 families like Araceae, Asparagaceae, Asteraceae, Boraginaceae, Chenopodiaceae, Combretaceae, Euphorbiaceae, Lythraceae, Myrtaceae, Oxalidaceae, Rhamnaceae, Rutaceae, and Solanaceae were sparsely found (2 to 4 species) while remaining 20 families had minimally one species each.
Based on 472 local informants, edible parts of these plants are eaten either in raw or cooked form by the local community. Maximum numbers of wild plants as fruits are generally eaten raw when they are ripe, and usually unripe fruits, seeds, flowers, and leaves are cooked as vegetables by the local people. In the case of individual edible plants, conventional and non-conventional processing is essential to make it palatable. For example, shoots of Bamboo, Agave, and Thoar (Euphorbia royleana) plants need to be peeled, boiled, and fried before consumption, whereas some plants can be directly consumed without processing. Underground parts (tuber) of Dioscorea species require washing, slicing, and boiling in salty water for a particular time and keeping them in salty water overnight to discard the tuber's acrid content. In addition to this, young pods of Cassia fistula are used to prepare pickles and Murabba (a sweet jelly preparation). Young shoots of Euphorbia royleana are being used to prepare vegetables by local people; this is perhaps a new kind of use not reported in the literature.
Local people of the region harness commonly available plants for food and vegetables, such as Aegle marmelos, Bauhinia variegata, Cordia dichotoma, Ficus carica, Ficus palmata, Phyllanthus emblica, Pyrus pashia, Syzygium cumini, Berberis asiatica, Punica granatum, Morus alba, Murraya koenigii, Colocasia esculenta, Amaranthus viridis, Amorphophallus paeoniifolius, Centella asiatica, Chenopodium album, Digera muricata, Ocimum basilicum, Viola serpense, Celastrus paniculatus, Dioscorea species, Monordica dioica etc. In this study, based on a survey, availability of plant, importance, and uses quoted by the informants, 21 plant species were screened for nutrient components and elemental analyses to evaluate their nutritional qualities (Table 2).
Table 2
Underutilized plant species selected from the study area from Hamirpur district of Himachal Pradesh for nutrient analysis
Voucher No. | Name of Plant species | Part used/ Analyzed | Area of collection | Period of collection | Time of collection | Informants (%) |
13E001 | Aegle marmelos (L.) Corrêa | Fruit (Ripe) | Badsar, Mehre | June, July, August | Day | ≤ 95% |
13E046 | Amaranthus viridis L. | Leaf/ young shoot | Hamirpur | August, September | Morning | ≤ 90% |
13E004 | Bauhinia variegata L. | Flower/ Bud | Samoh (Badsar), Salauni (Hamirpur) | January, February, March | Morning | ≤ 95% |
13E052 | Boerhavia diffusa L. | Leaf/ Young shoot | Singhmi (Barsar) | August, September | Morning | ≤ 70% |
— | Ceropegia sp. | Tuber | Darkotti, Nara, Samlehara (Barsar, Bijjari) | February, March, April | Day | ≤ 70% |
13E054 | Chenopodium giganteum D.Don | Leaf / Young shoot | Jhanjiani, Nain, Nara (Barsar, Bijari) | May, June, July, August | Morning | ≤ 80% |
13E0072 | Coccinia grandis (L.) Voigt | Fruit (Unripe) | Tikru, Charot, Bhadola (SujanpurTira) | August, September | Day | ≤ 85% |
13E043 | Colocasia esculenta (L.) Schott | Leaf/ Tuber | DharBagerah, Bahru (SujanpurTira) | July, August, September (Available in 12 months) | Morning | ≤ 90% |
13E008 | Cordia dichotoma G.Forst. | Fruit (unripe) | JolKalan, Tikkar (SujanpurTira) | June, July, August | Day | ≤ 95% |
13E057 | Digera muricata (L.) Mart. | Leaf/ Young shoot | Barsar, Sarai (Barsar, Nadaun) | August, September | Morning | ≤ 80% |
13E076 | Dioscorea alata L. | Airbulbils/ Tuber | DharBagerah, Kodana (SujanpurTira), Barsar | November, December | Day | ≤ 75% |
— | Dioscorea belophylla (Prain) Voigt ex Haines | Tuber | Dhaneta, Amroa (Nadaun), PathliarUparla (Barsar) | December, January | Afternoon | ≤ 85% |
13E074 | Dioscorea bulbifera L. | Tuber | Mehalkhass, Tikker | December, January | Afternoon | ≤ 50% |
13E075 | Dioscorea deltoidea Wall. ex Griseb. | Tuber | At Border area of Sujanpur Tira and Kangraa | October, November | Afternoon | ≤ 65% |
— | Dioscorea pentaphylla L. | Tuber | Nara, Upper Pathliar | January, February | Afternoon | ≤ 88% |
13E010 | Diospyros melanoxylon Roxb. | Fruit (Ripe) | The border area of Una and Hamirpur district | June, July | Day | ≤ 50% |
13E079 | Momordica dioica Roxb. ex Willd. | Fruit (Unripe) | Darkoti, Baroh (Bamson) | July, August | Day | ≤ 90% |
— | Moringa oleifera Lam. | Fruit | | | | |
13E024 | Pyrus pashia Buch.-Ham. ex D.Don | Fruit (Ripe, Unripe) | Amroa, Karari (Nadaun), Darkoti (Barsar) | November | Day | ≤ 85% |
13E025 | Spondias pinnata (L.f.) Kurz | Fruit (Unripe) | Baloh, Raj nauni (Nadaun) | January, February | Day | ≤ 70% |
13E084 | Trichosanthes cucumerina L. | Fruit (Unripe) | Hamirpur | August, September | Day | ≤ 83% |
a available on the high altitude range |
Evaluation of edible plants on nutritive values
A balanced and adequate diet constitutes two components, viz. food (nutrition) and functional food. Nutritional food mainly includes proteins, carbohydrates, lipids (fat). The nutritional value is the primary concern when a crop is being considered as a food source. Due to the emphasis placed on consumers' nutritional value, a great need exists for information on crops' nutritional contents [35]. However, an ideal edible plant species should be having the following qualities: a) rich content of proteins, carbohydrates, fats, dietary fiber, and minerals, b) balanced amount of nutraceutical substances, particularly vitamins C, E, and B12, c) Substantial amount of essential macro elements such as Na, K, Ca and Mg and microelements such as Fe, Cu, Zn, Mn, Ag and Au, d) medicinal importance e) economic importance and commonly available to the local people. Based on specific criteria like survey, availability, use, and application by the local people for food and medicine; therefore, we screened 21 plant species out of ninety for nutrient component analysis.
Carbohydrate
Similarly, the allocation of carbohydrates was calculated and presented in Fig. 1. Since carbohydrates are primary energy generating (yielding) substances, they are regarded as the chief energy source to each organism. They are mainly composed of starch and sugars. Among species, Dioscorea bulbifera showed the richest allocation of carbohydrate (80.57%), followed by A. marmelos (73.8%), D. alata (73.19) Ceropegia sp. (72.36%), and D. melanoxylon (72.2%). Remaining some other species (D. pentaphylla, T. cucumerina, B. variegata, P. pashia, and S. pinnata) also exhibited a comparable allocation range of carbohydrates. It has been noted that D. muricata has the highest allocation for protein but least for carbohydrates. However, a variable range of carbohydrates as total nutrients found in the selected species, where 50% species allocated 50% of carbohydrates and 25% species showed 30% allocation (Fig. 1).
Based upon this finding, few species such as D. bulbifera, Ceropegia sp., D. pentaphylla, D. alata, Bauhinia variegata, A. marmelos, and D. melanoxylon can be recommended as a good source of carbohydrates. The starch allocation was higher in all Dioscorea species except S. pinnata with the maximum allocation (37.0%). In agreement with our study, some earlier studies, for example, Baliga et al. (2011) reported 31.8% carbohydrate in the fruit of Aegle marmelos [42] and Zehra et al. (2015) reported 34.35% carbohydrates in the same plant species (Aegle marmelos) from Pakistan and another recent study [43], Binish and Pushpa (2018) revealed 34.43 to 46.16 g/100 g highest nutrient value of carbohydrates in tubers of three Ceropegia sp. [44].
Fat content
Fat is also the primary source of metabolic energy, which indirectly regulates the flow of materials into and out of the cell. Dietary fat serves as a carrier of vitamins, A, D, E, K, and hormones. In our study, allocation of fat of the total nutrients provides impressive results among all selected species. For example, Colocasia esculenta is rich in carbohydrates but provided the highest fat allocation, followed by Boerhavia diffusa and T. cucumerina. The least amount was recorded in the fruit of D. melanoxylon (Fig. 2). Generally, plant components, leaves, and seeds provide a rich source of fat. In our study, fat content was analyzed from leaf, and a high content was recorded, for example, C. esculenta, B. diffusa, C. giganteum, and A. viridis. Furthermore, few species were observed to have a high concentration of fat (lipid) content in the present study that can be an excellent fat source.
Generally, food plant species possess fat content ranging from 0.1–5% or even above. Earlier studies observed that edible plant species' fat content varies with species, parts, and area of study. For example, the fat content in Boerhavia diffusa was found to be 1.16% [45], whereas it was 0.7% in leaves of Amaranthus sp. [46]. Similarly, the fat content was reported about 1.8% [47] and 5.5–7.4% in the same speciesChenopodium quinoa [48], but from different study areas. These studies altogether support the present study's findings as the fat content of all leafy vegetables was approximately within the range recorded by earlier studies.
Protein
Dietary protein is the most critical constituent among all other nutrient components, primarily involved in the growth, maintenance, and repair of the body tissue. It regulates all the processes within the body [36]. Excess protein is used as a source of energy. Based on the allocation of total protein among selected plant species, Digera muricata is found most important edible species and is allocated with a high percentage of protein (46.52%) as of total nutrients (Carbohydrate + fat + protein) followed by A. viridis (22.73%), C. giganteum (19.82%) and Bauhinia variegata (17.97%), whereas, least allocation was found in Ceropegia species (1.46%). Sharma et al. (2011) and Usmani et al. (2014) reported protein content 78.0 mg/g and 4.3 (g/100 g) in Digera muricata respectively on a dry basis, which is lower than the present estimation of the same species [37, 38]. Out of all selected plant species, seven (07) species showed more than 10% while four species had less than 5% protein allocation. It was further observed that more than 15% allocation of protein was recorded in all leafy vegetable plants except C. esculenta. Specifically, one fruit plant (C. grandis) exhibited more than 15% protein allocation. Hence, those plants with a high protein percentage are presumably the most important edible species as a protein source that can be recommended to people deficient in protein nutrients. Therefore, the variation in the protein contents depends upon the season of collection, location and genetic variations of the species, etc. However, leafy vegetables' variation ranged from 0.33 to 21.79 g/100 g [39–40]. The lowest value (0.57 g/100 g) was found in the fruits of Trichosanthes cucumerina. The result of the same was confirmed and reported precisely by Badejo et al. (2016), who reported protein 0.37 to 0.51 (g/100 g on a fresh weight basis) in the same species [41]. The amino acid allocation was recorded maximum in the species like A. viridis (27.9%) followed by B. diffusa, C. grandis, M. dioica, C. dichotoma, and C. giganteum (Fig. 3).
Vitamin-C
Allocation of vitamin-C of total nutrients in the selected species reflected a contrasting range from 0.01-1.0%. S. pinnata had the highest allocation, followed by M. dioica, B. diffusa, A. viridis, and B. variegata (Fig. 4). However, 6–7 species showed an intermediate-range, but those species that showed a higher range of allocation for protein and carbohydrate had low allocation for Vitamin-C. Surprisingly, one species D. muricata with the highest allocation for protein, a substantial amount of carbohydrates, exhibited an acceptable range of vitamin–C allocation slightly lower than A. viridis (a leaf vegetable). Vitamin–C generally is a good source for immunity enhancement, protection from various diseases. Various workers [49, 50] have reported vitamin C content in Spondias pinnata in the range of 21–218 mg/100 g. In another study, Nirmala et al. (2007) reported contents of vitamin- C (3.0–13 mg/100 g) fresh weight basis) in the shoots of bamboo species [51]. In comparison, another study conducted by Badejo et al. (2016) reported 39.32–56.58 Vitamin C content in the fruits of Trichosanthes cucumerina on a dry weight basis [41], which is in line with our findings.
Vitamin-E
B. diffusa had the highest allocation of vitamin-E followed by C. giganteum and S. pinnata whereas it was lowest in Ceropegia sp. and C. dichotoma (Fig. 5). The remaining 18 species were found in the range of 0.001–0.009%. Important vitamin-rich plant species mentioned above can be recommended as healthy diets, especially for nutrient-deficient areas. Vitamin–E is required for skincare, hair growth and also regarded as a beauty vitamin. It is a powerful antioxidant that protects the heart, blood vessels, chest pain, high blood pressure, blocked arteries, anti-aging, cancer, liver toxicity, etc. [52]. The range of vitamin-E content was varied from 0.05 to 16.4 mg/100 g in different species mentioned above by different workers [53–54]. Hence, these plants such as Aegle marmelos, Pyrus pashia, Spondias pinnata, Boerhavia diffusa, Chenopodium giganteum, etc. can be considered the sources for vitamin E supplement for local people, if it is commercialized, rest of other people would be benefitted more.
Relative nutrient value index (RNVI)
RNVI was calculated as a summation of the proportional value of major components such as protein, carbohydrate, and fat of each species. This provided adequate information for the evaluation of a plant species. Values for RNVI varied from 7–36, in which the highest was estimated for C. esculenta (34.76) followed by A. marmelos (31.32) and D. deltoidea (30.91). Local people of the study site also informed about its efficacy for edible and medicinal purposes. Across species, ten species had RNVI value in the range of (20–30), and three species had above 30 index values (Fig. 6). Taro corm (C. esculenta) is a good source of minerals. Its starch's small granule size helps increase its nutrients' bioavailability due to the efficiency of digestion and absorption [55].
Relative functional food index (RFFI)
TRFFI was calculated in the same way that it also provides sufficient information about rich food value content such as vitamin-C, E, total phenol, and phytosterol. Based on the analyzed concentration of phytosterol and phenol, it is not easy to figure out the species' quality. However, through this index, it is found that S. pinnata (34.81) had a higher or better index for functional food value, followed by Dioscorea alata (26.11), Bauhinia variegata (26.01), C. giganteum (25.44), Dioscorea pentapyhlla, (24.44) and Moringa oleifera (21.18). The remaining four species exhibited TRFFI value around 20 (Fig. 7). Since functional food is the composition of phytosterol, total phenol, and vitamins, they are required for protection from harmful diseases [56–57].
Generally, phytonutrients are present in the foodstuff. They may be used as food supplements and as medicinal food. Based on a single constituent like total phenol or phytosterol, it might be challenging to evaluate the quality of species for functional food value. Hence, this index provides satisfactory results. Based on this index, S. pinnata, D. alata, D. pentaphylla, C. giganteum can be recommended as a good source for functional food development. They are known to have several bioactive properties with possible implications for human health, such as the serum cholesterol-lowering effect, that might prevent colon cancer and benign prostatic hyperplasia [58]. Recommended daily dietary intake of naturally occurring phytosterols is ranged from 150–450 mg/day. Intake of Phytosterol is negatively correlated with cholesterol absorption.
Relative Dietary fiber index (RDFI)
RDFI is calculated in a similar way to another index like TRMI and TRFFI. Values for respective index varied from 9.05–35.61, in which C. esculenta (35.61) and C. giganteum (35.53) both had the highest while Ceropegia species exhibited the lowest value of RDFI (Fig. 8). Across species, 12 species showed 12–25 IRDF values while eight species had in the range of 10–12. This index can act as a better tool to distinguish species having a rich source of fiber content. Therefore, through this index, we found these two species to have surprisingly better fiber content, followed by C. dichotoma (32.06), P. pashia (29.48) A. viridis (29.38), leaf of C. esculenta (25.92), and Digera muricata (25.36) respectively. Nirmala et al. (2011) and Bajwa et al. (2016) reported 0.51–1.93 g/100 g (fresh weight) in the shoot of Bamboo species [18, 59]. Modgil and Sood (2015) and Vilcacundo et al. (2018) recorded dietary fiber of leafy plant species within range with our findings [60, 48]. Plant food contains non-digestive carbohydrates like ADF, NDF, cellulose, hemicellulose, and lignin. These indigestible carbohydrates are designated as dietary fiber. Intake of dietary fiber has essential metabolic and physiological effects. Though they do not constitute the nutritive value of foods. The presence of fiber is commonly called roughage of diet, which is necessary for digestion and elimination of waste. It helps to solve constipation, blood glucose, reduce the risk of colon cancer, etc. Hence, these plants can be used as better sources of dietary fiber. In 2015, the government published new guidelines to recommend that fiber intake should increase to 30 g a day for adults for more than 17 years.
Relative mineral index (RMI)
About 12 main elements (Ca, Cu, Fe, K, Mg, Mn, Ni, P, Zn, Na, Si, S) are considered to calculate this index. Values for the corresponding index (TRMI) varied from 13-174.03 in which D. muricata exhibited the highest value, followed by A. viridis (101.39), C. esculenta (98.45), C. giganteum (85.04), B. diffusa (73.25), and Ceropegia (67.1). The remaining other species (12) had a more or less similar range of (IRMN) while 8 species had a range below 30 (Fig. 9). This index probably provides valuable information and evaluates mineral enrichment of the species. D. muricata with highest protein allocation and highest mineral nutrients indicates that this plant can be recommended as a good source for protein and minerals rich species. In India, malnutrition is a common problem in women, older people, and children below 12, mainly residing in remote rural areas. However, if present in the plant, these elements may be a good substitute for food and a source for those specific elements required for curing ailments of a human and veterinary purpose. Some minerals are essential to the human body, e.g., such as calcium, potassium, magnesium, sodium, phosphorus, and chloride. These are required in a large amount while others in a small quantity, usually less than 0.01% of the total body weight [57].
Most rural people suffer from malnutrition not because of the economic status but because of the inability to utilize the available nutritious underutilized crops to meet their daily requirements. There must be a need to see the economic and nutritional impact of indigenous fresh underutilized crops for its production and consumption in rural communities to meet the nutritional demand. Therefore, it can be useful for malnutrition and food insecurity for rural peoples as rural food sources. The metabolic fate or role of each element in the plant can be characterized in relation to some basic processes such as uptake (absorption), transport within plants, concentration, metabolic process, and deficiency and toxicity. Generally, plants absorb elements through roots from the soil and aerial parts like a leaf, also known as foliar uptake, which occurs in two-phase non-metabolic cuticle parts and metabolic transportation across the cell membrane. Some elements such as Cu, Fe, Mn, Mg, and Zn play a crucial role in plant metabolism and are constituents of several enzymes.
The trace elements play an important key role in human metabolism. Low food quality has created severe problems for the people; this situation is alarming, especially in developing nations where most people do not have sufficient food even in one-time food intake. However, more surprising facts are that those people who are getting enough food (three times daily) are undernourished. Nowadays, over three billion people worldwide suffer from either deficiency or where presence in excess may result in toxicity of some elements. Some trace elements are essential for chemical, biological, biochemical, metabolic, catabolic, and enzymatic activities in plants, animals, and human beings. Trace elements can remain in the body organs for a long time. It has been reported that more than 60 elements have been detected from the human body in which about 25 elements are essential for human health, where 14 are trace metals that can prevent malnutrition.