Introduction
Lemongrass (Cymbopogon citratus) is a warm-season grass, that is a sub-tropical, as well as, tropical plant that is a perennial grass of Graminaceae family and genus Cymbopogon. It is a native plant with medicinal and fragrant characteristics. At local levels, it is identified with various names, such as ‘Gawati Chah’, ‘Nibugrass’, and ‘Puthiganda’. In the subcontinent region, approximately three lemongrass species have been identified. The lemongrass that is grown in the eastern region of India is well known for its oil and has a growing market.1 Lemongrass, a potential source of essential oils, is also a good potential source of phytochemicals that have pharmacological activities.2
As implied by its name, the plant is unique because it contains unstable oil that gives off a beautiful lemon scent. It is used as a healing ointment worldwide. Over 16,000 acres of lemongrass have been developed globally producing approximately 1,000 tonnes of lemongrass. Such production includes bulbous stems 100 cm long and 2 cm broad terete and glabrous leaf sheaths with a pointy edge, a narrow base, and a dramatic apex.3,4 Several bioactive compounds can be found in the decoction, infusion, and essential oil isolates of lemongrass. Lemongrass tea has been shown to have antioxidant, anti-inflammatory, antibacterial, antiobesity, antinociceptive, anxiolytic, and other properties that support pharmacological claims about its properties. In several developing nations, alternative medicine practitioners widely embrace lemongrass tea because it is non-toxic, non-mutagenic, and safe.5
The aqueous extracts of lemongrass leaves possess hypoglycemic and hypolipidemic potential.6 Lemongrass extracts have been reported to cure dermatitis. Depending on the age of the grass the composition of the oil changes. Fresh lemongrass produces 0.67% essential oil, which has a high citral content, while dry lemongrass produces 0.4% essential oil, which has a citral content of 72.3%.7 Several studies confirmed that people of the subcontinent used lemongrass to cure headaches, nausea, colds, and rheumatic pain.8 High concentrations of antimicrobial and antioxidant components are present in lemongrass extracts and oils.9 Flavonoids, alkaloids, tannins, terpenes, phenolics, anthocyanins, steroids, saponins, isoflavones, coumarins, lignins, catechin, isocatechins, and ascorbic acid are among the many beneficial bioactive compounds present in lemongrass oil.10
From ancient times, herbal teas belonging to a range of scientific families, are typically used to cure fevers, hacking, colds, and as a pleasant tonic or beverage.11 Herbal plants like lemongrass have been used to ease stomach pain, encourage perspiration, and produce mucus, as well as, being widely used for the treatment of gout.12 Freshly cut and, to some extent, dried leaves of lemongrass are used for medical purposes and are the source of therapeutic oil. Many medicinal properties of Cymbopogon citratus include anti-amoebic, anti-bacterial, protection against intestinal looseness, anti-filarial, and anti-parasitic properties.13 For different efficacy investigations to evaluate various health effects, Wang et al.14 reported that extracts from lemongrass leaves have health-protective mechanisms.
Ethanolic and acetone extracts in polyphenols of lemongrass powder (LGP) had significantly higher antioxidant activities of their ethanolic extracts as compared to their acetone extracts.15 Lemongrass leaves are a source of essential oils, which have an extraordinary role as natural preservatives due to their antimicrobial and antioxidant potential.16 Due to their qualities as anticancer, antiviral, calming, anti-microbial, as well as, allopathic properties, phenolics and flavonoids are two types of polyphenols present in lemongrass, which have exhibited antioxidant and antimicrobial behavior in chicken sausages.17
As the world emerges from the destructive pandemic period, eating the right foods can help to develop and strengthen adaptive immunity. Plant-based foods, due to the presence of functional and nutraceutical components, are a useful part of a daily diet. In the post-COVID era, a sufficient supply of healthy foods that are balanced with pharmaceutical foods may play a fundamental role in boosting the immune systems of the populace.18 As part of this functional food covenant, global communities are looking for fresh, nutritious food items that are rich in bioactive ingredients like fiber, minerals, vital amino acids, and phenols.19 Worldwide consumption of bakery products like biscuits and cookies is high; however, such foods lack adequate nutritional value. To enhance bakery products with phytochemicals like phenolics, flavonoids, vitamins, minerals, carotenoids, natural colorants, and fiber, the substances from powdered plants, herbs, fruits as well as vegetables may be used as functional ingredients.20 Different parts of plants may be extracted to obtain condensed phytochemicals, which exhibit strong antioxidant potential upon consumption.21
Despite the use of extracts, essential oils, and isolates from lemongrass for medicinal purposes, the scientific community has only started to realize the importance of pharma foods, such as those equipped with phytochemicals that are transferred from medicinal plants. For such purposes, recent advances have been made including, the manufacture of functional yoghurt with lemongrass extracts,22 the development of lemongrass-flavored high-nutrient cookies,23,24 and the production of lemongrass-incorporated meat sausages.17 Compared with previous food product development, in current studies comparatively high levels of LGP were investigated for the development of nutritional biscuits, which were analyzed for phytochemical and sensory characteristics. To fulfil the need for healthy, pharma foods, the objectives of the current research were to convert lemongrass leaves into powder and then into ethanolic extracts for estimation of phytochemical composition. Such undertaking was done to create nutritional biscuits using different replacement levels of LGP and to analyze the phytochemicals, mineral profiles, and proximate composition of such biscuits. The evidence regarding the phytochemistry of lemongrass and the possible applications of LGP in food products were taken into consideration when completing the research.
Discussion
Higher contents of ash and fiber were positive indications for utilizing LGP as a source of functional components in food products. Radwan and Elmaadawy provided the values of ash, fat, fiber, protein, and moisture contents of LGP,34 which did not differ significantly from those currently documented. Hussain et al. performed a proximate analysis of white flour before the development of nutritional biscuits and provided values of moisture, ash, fat, fiber, and protein contents in white flour as 13.56, 1.05, 0.97, 0.72, and 10.11 mg/100 g, respectively.25 Such values were closely related to the results of the present study where the authors identified lesser amounts of ash, fat and fiber contents in wheat flour as compared to LGP. Figure 1 presents the summarized work plan conducted on lemongrass and lemongrass powder incorporated biscuits.
Thorat et al. produced LGP and determined proximate composition of lemongrass fresh leaves and then developed powder,24 with values of moisture, ash, fat, protein, and carbohydrates recorded at 7.01, 11.28, 1.45, 11.15, and 65.78%, respectively. Reported higher values of ash and protein may be due to cultivation and climate differences of the lemongrass that affect the chemical composition among the same varieties of the same crops. From the results of Thorat et al.,24 it was evident that there is a decrease in moisture, protein, and fat content and an increase in carbohydrates, fiber, and ash content of wheat flour-based bakery products that occurred due to the specific proximate composition of LGP. Similar results for proximate analysis of LGP were also present in the research work of Irfan et al.,15 highlighting the higher contents of ash and fiber.
Performing similar experiments on lemongrass, Asaolu et al. reported moisture,35 protein, ash, and fiber contents in LGP as 5.76, 4.56, 20.30, and 55%, respectively. Higher values of fiber and ash contents in their study might be due to environmental and agricultural land factors. Alemayehu et al. evaluated another medicinal plant,27 nettle leaves (Urtica simensis) flour for proximate composition and results revealed that this plant contained a sufficient amount of ash, protein, and fiber, to be utilized in wheat flour for the development of noodles, and this can be connected with the present research, as use of medicinal plants powders could prove helpful in the development of pharma foods.
Birhanu et al. determined some important minerals present in lemongrass and the results supported our study.36 Significant amounts of iron, zinc, magnesium, calcium, and potassium were found in lemongrass. According to the results, lemongrasses are an important origin of essential minerals. The mineral concentrations in the examined samples fell under WHO’s maximum allowable limits, making them safe for consumption by people. Their data reflected the average content of calcium, magnesium, potassium, iron, and zinc in LGP, which were closely related to the present findings. Giving findings just in line with current ones, Ranade and Thiagarajan reported that LGP contained high calcium,37 phosphorus, and potassium values. The deficiency of wheat flour for zinc and iron was reported by Hussain et al. when they provided the respective values of iron and zinc as 2.85 and 2.63 mg/100 g of white flour,25 which was closely related to the findings given in the current work, and these values were much less than present in LGP.
Several earlier investigations have provided strong scientific evidence about the presence of both trace and macro minerals in wild and domestic medicinal plants, due to which these plants and their powders find their route into pharma foods. Asaolu et al.35 explored some macro and trace minerals in LGP and found sufficient quantities of Se, Zn, Fe, Ca, Cu, and K. They reported slightly higher values of Fe and Zn in LGP as compared to current results, and such variation in results might be due to several factors including maturity stage of the plant used, cultivation environment, genotype, and techniques adopted for analysis. While performing similar research work, Alemayehu et al. explored mineral contents in a wild medicinal plant powder,27 before its utilization in extruded product. They reported that nettle leaves (Urtica simensis) flour possessed sufficient amounts of iron, zinc, and calcium.
Phenolics, flavonoids, and carotenoids are among the important phytochemical classes, known for their health-promoting potential, as they stop the onset of many diseases. Bioactive substances are essential for human nutrition and health.38 In greater amounts, the antimicrobial and antioxidants are present in lemongrass oil. Extracts and oils of lemongrass, both rich in several beneficial bioactive substances other than phenolics and flavonoids, which are alkaloids, tannins, anthocyanins, steroids, terpenes, saponins, isoflavones, coumarins, lignins, catechin, isocatechins, as well as, ascorbic acid, and all such components have their positive role in scavenging free radicals thus acting as antioxidants.9,10 Thorat et al.24 analyzed phenolic and flavonoid components in lemongrass extracts and the results did not differ greatly from this study. Similar findings have also been documented in the experiments of Irfan et al.,15 as they used acetone and ethanol as solvents for extraction of LGP and observed higher contents of TPC and TFC in ethanolic extracts with higher antioxidant activity, strengthening the use of ethanol as an effective solvent for maximizing phytochemicals from LGP. Falah et al. reported that the extract of lemongrass in 70% ethanol had the lowest IC50 value (79.4) and the highest DPPH inhibition,39 which displayed the strong antioxidant potential of this important herb, just as was proven by our experiments.
In another similar study, Asaolu et al. investigated lemongrass extracts for the presence of phytochemicals and found appreciable values of phenolics,35 flavonoids, alkaloids, saponins, tannins, and steroids, which have a strong relationship with health benefits. Further, they reported that extracts of lemongrass exhibited strong antibacterial activities also, against selected bacterial species. Relevant findings were also seen when Lu et al. used three different methods to determine the antioxidant activity of lemongrass extracts and reported that lemongrass extracts possess significant antioxidant activity very compatible with ascorbic acid,9 gallic acid, and quercetin. As in the current experiment phenolics, flavonoids, and antioxidant activity were calculated in equivalence to the same standards. Polyphenols, which are renowned for their anti-inflammatory and antioxidant properties, are abundant in lemongrass. In an experiment exploring lemongrass oils and extracts, an aqueous residue was produced after hydro-distilling lemongrass essential oil and was found to have a similar phenolic profile as lemongrass extracts and oils. Aqueous waste and extracts of lemongrass, both exhibited strong DPPH free radical scavenging and anti-inflammatory activities in safe modes, without any toxicity,10 which proved that ethanolic extracts, as well as, aqueous extracts of lemongrass have sufficient bioactive compounds to be utilized as medicinal agents.
The medicinal importance of lemongrass extracts has been widely recognized around the globe. Lemongrass extracts, when applied to animals, exhibited hypoglycemic and hypolipidemic activities, which might be attributed to the bioactive components present in this medicinal herb.6 Boeira et al. extracted bioactive components from lemongrass and incorporated them in meat products to check their antimicrobial and antioxidant activities.17 They stated that phenolics and flavonoids are the major bioactive compounds responsible for such medicinal properties. To reduce the risk of drug-related toxicity and improve the effectiveness of the therapy, lemongrass extracts may be used in conjunction with chemotherapeutics. Lemongrass extract has been shown in a clinical trial to have selective anticancer activity.40 Mohamed et al. proved that as compared to the gentamicin group alone,41 the rats treated with LGP and gentamicin exhibited substantial alterations in blood urea, nitrogen, and creatinine. During the blood biochemical studies, the use of lemongrass extract to treat the liver and kidney tissues improved the health of rats. Such findings can be related to the presence of phenolics and flavonoids, which have antioxidant potential in animals.
In a food material ash content is the non-organic compounds in the food that contain mineral content. Nutritionally, it helps in the process of metabolism of other organic compounds such as carbohydrates and fats.42 Kukade et al. performed a similar experiment by developing lemongrass-flavored high-nutrient cookies.23 Three cookies were prepared by the substitution of wheat flour with poppy seed flour and LGP in different ratios and then were tasted for moisture, ash, protein and crude fiber, etc. The results showed that calorific values like fat, moisture, and fiber, among others were increased by using enriched wheat flour in place of refined wheat flour. Outcomes from the study of Radwan and Elmaadawy were in line with current results where investigators developed nutritional bread by incorporating LGP at various levels to find a remarkable increase in ash and fiber contents of the developed bread.34 Ash and fiber contents in control bread were 1.20 and 5.72% respectively, which were increased to 1.48 and 6.34% in bread developed with 10% LGP. Supportive findings were also in the studies of Thorat et al. when they incorporated LGP in cookies at different levels and observed increases in ash, fat, and fiber contents of cookies.24 The increment of ash and fiber contents of biscuits developed as a result of the incorporation of lemon pomace powder was recently reported in the study of Hussain et al.43
The development of herbal cookies by Yadav et al. also indicated that the addition of organic herbs reduced the moisture contents in the developed cookies.44 The low contents of moisture in supplement cookies were because of the low water absorbability and low water contents of incorporated herbs, which also support our research, as the addition of LGP into the developed biscuits reduced the moisture contents in LGP fortified cookies. Similar results obtained from the work of Dias et al.,45 can also be used here to support our findings as they performed the nutritional assessment of composite cookies of wheat flour incorporated with herbal plant powder. The level of ash, fat, protein, carbohydrate, and fiber of the herbal powder incorporated biscuits was in the range of USDA National Nutrient Database for Standard Reference. This research was also an indication that the fortification of lemongrass increases the ash, fat, and fiber contents.
Development of some other food products by incorporation of herbal plants powders was also observed in some studies, as Alemayehu et al. incorporated wheat flour with dried nettle leaves (Urtica simensis) flour to develop noodles and noticed a noteworthy increase in moisture, ash, protein, and fiber contents of formulated noodles,27 whereas carbohydrates and fat contents were found in decreasing order. Their results supported the findings of the present research, that wild and medicinal plant powders can be used as nutritional ingredients in bakery and extruded snack products.
Minerals are essential for human nutrition to regulate various metabolic processes in the body and also provide support to the skeleton. Higher consumption of cereal-based bakery items has led to the deficiencies of important minerals in humans, which can be encountered by the incorporation of non-wheat flour from plants, fruits, and vegetables into wheat flour for the development of nutritional food products.46 The high mineral contents of lemongrass are the foundation for the rise in calcium, iron, zinc, and other minerals in incorporated biscuits. Infants and young children need calcium for healthy growth and development, while iron and zinc are essential for metabolism and immunity. Magnesium is another mineral that is abundant in carrots. Magnesium is necessary for the synthesis of bone, protein, and new cells, the activation of B vitamins, the relaxation of muscles and nerves, blood coagulation, as well as many other human metabolic processes.47
Birhanu et al. experimented to study the levels of trace and major minerals in lemongrass.36 After analysis of lemongrass through wet acid digestion, it was evaluated for minerals, utilizing the recovery test. Lemongrass was stated as the efficient source of minerals as the recovery percentage ranges from 86.9% to 106% and was all obtained from identified metals. The concentrations of metals K, Ca, Mg, Fe, Mn, Cu, Zn, and Pb range from 743.8 to 1,020, 123.1 to 129.3, 23.9 to 36.3, 10.35 to 22.3, 10.0 to 12.7, 1.48 to 2.53, and 0.59 to 1.07 mg/ kg, respectively. The results of this research showed that lemongrass was a beneficial and efficient source of essential metals, and variations in quantities of minerals are dependent upon several factors like cultivar, genotype, maturity, purity of chemical used and techniques adopted for analysis. Similar, increments in the mineral contents can also be taken from the work of Bolarinwa et al.,48 in which nutritional values and acceptability of the bread fortified with moringa were determined. Their study reported that the fortification of organic herbal plant powders significantly increased the mineral contents of wheat bread. Similar research was conducted by Boriy et al. when herbal extracts fortified pan bread were developed,19 and the results of this finding were quite supportive of our work, as the chia seeds fortified bread had high values of minerals like magnesium, iron, zinc, and potassium.
Agrahar-Murugkar created fortified bread and biscuits by substituting refined wheat flour with herbage,49 African millet, seed, and spices, for enhancing the bio-accessibility and improvement of Ca, Zn, and Fe, among others. Their study’s findings demonstrated the effectiveness of fortified bread and biscuits as a source of bio-accessible minerals and their role in enhancing dietary mineral status. Another example of the incorporation of herbal plant powders for the development of nutritional food items was observed when Alemayehu et al. dried nettle leaves (Urtica simensis) to develop nutritional flour and incorporated in wheat flour for the development of noodles.27 By comparing the formulated noodles with the control sample, they concluded that a significant increase in essential minerals like calcium, iron, and zinc was observed in noodles, which was credited to the high mineral contents in the powder of the medicinal plant used. The observations of Hussain et al. also produced similar outcomes to those herein,25 as they reported an increase in iron and zinc contents of wheat biscuits when incorporated with different portions of pumpkin powder.
Lemongrass methanolic extracts were involved in antioxidant and antimicrobial activities, which was probably due to their high TPC and TFC values.50 In another study, three different varieties of lemongrass were tested for their phytochemical and antioxidant potential, and the results were promising, indicating the directly proportional relation between TPC and DPPH free radical scavenging activities of lemongrass extracts.51 Revealing the medicinal importance of this medicinal herb, fresh and dried lemongrass leaves were compared with commercially available teas for the presence of phytochemicals and antioxidant activities, and results showed that this herbal plant has sufficient amounts of TFC and TPC with high antioxidant capacities.52 The antioxidant effect of lemongrass was tested in another study, when lemongrass oils were introduced in soya bean oil, and DPPH assay was performed to calculate free radical scavenging activity. Further, the TPC and TFC of formulated oils were also higher.53
While baking cookies, made with the incorporation of different nutritional flours with high TPC and TFC values, it was observed that baking did not affect the TPC of the flour or dough, but slightly decreased the level of TFC, nonetheless benefitting consumers by increasing nutrition through the incorporation of different plant flours in cookies. In addition, it was shown that the developed cookies contained high phytochemicals.54 Another study by Dias et al. reported the presence of phytochemicals including flavonoids, phenolics, alkaloids, saponins and tannins in herbal cookies,45 developed to promote human health.
Polyphenols are the most prevalent and easily available phenolic contents in plants, and according to Valenzuela et al.,55 plants contain large amounts of polyphenol compounds, which give them many of their antioxidant qualities. The amount of DPPH free radicals that can be scavenged is directly proportional to the polyphenol content. Euphorbia eriophora, a medicinal plant, was shown to have DPPH free radical scavenging activity, and it was established that a lot of products can benefit from using this native plant as a natural antioxidant agent.56
Many examples from earlier studies showed that adding plant powders to biscuits increased their TPC equated to normal wheat flour biscuits. In a study, Ismail et al. measured the TPC and DPPH free radical scavenging activities of the developed cookies by adding pomegranate peel powder in various ratios to straight-grade flour.57 Cookies made with 100% straight-grade flour had a TPC of 90.70 mg GAE/100 g, and as the replacement amount of pomegranate peel flour was raised, a discernible rise in the TPC of cookies was observed. By adding pumpkin peel, flesh, and seeds powders in various quantities to nutritional biscuits, Hussain et al. achieved results that were remarkably similar to those of the current study in terms of the biscuits’ capacity to scavenge free radicals, as TPC, TFC, TC, and DPPH activity were raised.58 Choi made pine needle cookies that were shown to have a modest DPPH activity (6%) when made with 100% wheat flour,59 but a large increase (60%) was seen when up to 5% pine needle flour was added. Also, he concluded that cookies with higher total phenolic contents exhibit greater antioxidant activity.
The sensory properties of the herbal biscuits incorporated with LGP, including color, flavor, taste, texture, and overall acceptability, were evaluated using a 9-point hedonic scale. Increased LGP content over 3% has a negative impact on the sensory quality of cooked cookies, as was reported by Thorat et al.,24 after an experimental study, whereas our experiments concluded that up to 5% level could be acceptable for the development of good quality biscuits. Supportive findings were also present in the trials of Hussain et al. observing the use of fruits and vegetable powders at lower levels proved beneficial to develop acceptable bakery products.25 The current study’s findings were also supported by the sensory analysis of a study by Bolarinwa et al.,48 which showed that the bread made with 5% moringa was not significantly different from the bread made with 100% wheat flour, in terms of the majority of the quality attributes assessed. Similar findings were also present in the research work by Boriy et al. during the development of pan breads,19 as suitable levels of incorporated powders can provide the required quality of bread.
Similarly, the sensory attributes of lemongrass and lime juice incorporated beverages developed by Kieling and Prudencio60 were significantly positive on the 9-point hedonic scale. The results derived from the acceptance levels, based upon the characteristics of color, flavor, and aroma, among others, of that study suggested the high-level possibilities of incorporation of lemongrass constitutes in various food commodities would possibly bring positive acceptance outcomes. This would also help the consumers to attain better health and nutrition status by utilizing the properties of various constituents present in these fortified commodities. Findings of a recent study by Hussain et al. also witnessed that suitable replacement levels of flour from lemon pomace provided optimum quality biscuits with high nutritional components.43
According to Abdel-Naeem et al.,61 using powders from lemon, orange, grapefruit, and banana peels increased the organoleptic scores for chicken patties in terms of color, aroma, appearance, and tenderness. The developed final products were well received by the judges, opening up new avenues for the development of dairy, bakery, beverage, and meat products by using non-wheat powders from medicinal plants. Similar results were also present in the studies of Alemayehu et al. when they developed noodles with different formulations of wheat flour and a medicinal plant powder.27 They reported that a 5% incorporation level was found to be acceptable as this product produced good scores, close to the control. The presence of more flavoring compounds and polyphenols in LGP may account for the decreased flavor and taste scores of biscuits with 7.5 and 10% LGP replacement, while the presence of more fiber may also contribute to the decreased texture scores with higher LGP levels. Low scores of overall acceptability and appearance are a result of the 10% LGP biscuits’ more yellow to greenish hue, which is a result of natural pigments found in lemongrass.