INTRODUCTION:

In developing nations, the utilization of various wild edible plants as food sources is prevalent. Many individuals gather these plants from their natural environments to address nutritional needs, prompted by factors such as population growth, limited arable land, and soaring prices of staple foods.

Often driven by dietary customs, cultural practices, and taste preferences, rural communities cultivate a diverse array of wild vegetables without formal cultivation. These wild edibles have garnered substantial attention in recent times due to their crucial role in human diets, providing essential proteins, energy, vitamins, minerals, and hormone precursors. The presence of macronutrients like proteins and carbohydrates in these wild edibles contributes to reducing the risks of ailments such as cancer, coronary heart disease, and diabetes¹.

Phenolic compounds, a class of phytonutrients with potent antioxidant properties, encompass simple phenols, phenolic acids, hydroxycinnamic acid derivatives, and flavonoids. Antioxidants present in food safeguard the body against free radicals, including reactive oxygen species, which contribute to age-related degenerative diseases. The significance of antioxidants and their relationship to disease susceptibility has gained prominence as various bioactive substances with potential antioxidant effects have been identified in food^2-3.

Natural antioxidants, including vitamins, carotenoids, flavonoids, and phenolic compounds, are abundantly found in fruits and vegetables^4-5. The connection between these antioxidants and disease prevention has piqued interest, particularly due to their potential to counteract oxidative stress⁶. The consumption of vegetables has consistently shown to have a protective impact against various age-related conditions like cancer, cardiovascular diseases, cataracts, and macular degeneration⁷.

Cooking methods, commonly boiling or microwaving, are employed to prepare most vegetables for consumption. These techniques can significantly alter the physical attributes and chemical composition of vegetables⁸. Studies have shown that while boiling and baking have minimal impact on the total phenolic content and lycopene content of tomatoes, frying notably diminishes the antioxidant activity⁹. Similar effects have been observed for broccoli, where cooking influences both antioxidant components and activity⁵. Thermal treatments have been found to decrease total phenolic content and antioxidant activity in vegetables like kale, spinach, cabbage, swamp cabbage, and shallots¹⁰.

Traditional cooked vegetables, including green beans, peas, peppers, squash, broccoli, leeks, and spinach, are widely consumed, with wild vegetables also being prepared in this manner. However, there's a dearth of information in existing literature regarding the effects of cooking on antioxidant activity and total phenolic content of these vegetables. This study was undertaken to fill this gap by investigating the impact of various cooking methods on the antioxidant activity and total phenolic content of Perilla ocymoides, Clerodendrum colebrookeanum, Solanum gilo, Solanum kurzii, and Potentilla lineata collected from different locations within Meghalaya State, India.

MATERIALS AND METHODS:

Plant materials:

The freshly harvested edible portions of plant materials, namely Perilla ocymoides, Clerodendrum colebrookeanum, Solanum gilo, Solanum kurzii, and Potentilla lineata, were sourced from the North-Eastern region of India. To ensure accurate identification, the botanical authenticity of these specimens was confirmed by the Botanical Survey of India in Howrah. To maintain a record of these identifications, voucher specimens were meticulously preserved within our organization's Plant Chemistry department, each assigned a distinct registry number: BSITS 6, BSITS 7, BSITS 8, BSITS 9, and BSITS 10, respectively.

Subsequent to harvesting, the plant parts underwent a process of shedding and drying, following which they were ground into a fine powder. This pulverized material was then securely stored within a tightly sealed container to prevent any external influence. To comprehensively assess the impact of diverse cooking techniques on both antioxidant activity and total phenolic content, a series of experiments were conducted within our laboratory.

Chemicals:

1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), butylated hydroxytoluene (BHT), ascorbic acid, quercetin were purchased from Sigma Chemical Co. (St. Louis, MO, USA)., Folin-Ciocalteus’s phenol reagent, gallic acid, potassium ferricyanide, potassium per sulphate, Aluminium chloride, FeCl₃ and sodium carbonate were from Merck Chemical Supplies (Damstadt, Germany). All the chemicals used including the solvents, were of analytical grade.

Cooking by boiling:

For each powdered plant sample (5g), a procedure was employed where they were subjected to boiling in distilled water at a temperature of 100°C. This boiling was carried out using a ratio of 1:10 (weight-to-volume) on a hot plate, and the process continued for a duration of 1 hour or until the plant materials reached a tender state and were depleted of their original properties. Following the boiling process, the plant materials were separated from the water through the utilization of a sieve. Subsequently, the boiled plant samples were carefully dried in an air oven set at a temperature of 50°C for a period of 2 hours. The purpose of this drying process was to eliminate any residual moisture. The dried plant samples were then set aside, ready for further investigation and analysis¹¹.

Cooking by microwave heating:

A standardized procedure was employed for each powdered plant sample (5g), involving the placement of the sample within a glass beaker. Distilled water was then added in a ratio of 1:10 (weight-to-volume), creating a suitable mixture. This mixture was subsequently subjected to cooking within a microwave oven, a process lasting for 15 minutes. The aim was to attain a softened consistency of the plant materials.

After the microwave cooking, the softened plant materials were meticulously separated from the water in which they were cooked. Following this separation, the plant materials underwent a drying procedure in an air oven at a controlled temperature of 50°C. This drying process spanned a duration of 2hours, effectively removing any residual moisture from the cooked plant samples. Once the drying process was complete, the samples were prepared for further analytical investigation¹¹.

Extraction of plant material:

For each type of plant material, both raw dried and cooked, a quantity of one hundred grams (100g) was used. These plant materials underwent extraction using 80% aqueous ethanol. The extraction process involved two cycles, and for each cycle, the plant materials were subjected to agitation for a period of 18 to 24hours at room temperature. The concentrated solutions obtained from both the initial and subsequent extractions were combined and concentrated further through the use of a rotary evaporator under reduced pressure. This process led to the formation of viscous extracts. These extracts were then subjected to additional drying using a freeze dryer. The resultant dried extracts from both the raw and cooked plant samples were stored at a temperature of minus (-) 20°C until they were ready for use. The dried extracts obtained through the utilization of 80% aqueous ethanol were carefully weighed. To assess the efficiency of the extraction process, the percentage yield was calculated. This percentage was expressed in relation to the air-dried weight of the original plant material.

Estimation of total phenolic content:

The total phenolic content of the crude extracts was determined through the application of the Folin-Ciocalteu method¹². In this procedure, test tubes were employed, and varying volumes (ranging from 20 to 100 µl) of the samples under examination were introduced into these tubes. To the extracts, 1.0 ml of the Folin-Ciocalteu reagent was added, followed by the addition of 0.8 ml of a sodium carbonate solution (7.5%). Subsequent to these additions, the contents of the tubes were thoroughly mixed and allowed to stand for a duration of 30 minutes. The measurement of absorption at a wavelength of 765nm was then performed using a UV-visible spectrophotometer (Shimadzu UV 1800). The quantification of the total phenolic content was expressed in terms of gallic acid equivalents (GAE) per 100grams of dry plant material, denoted as mg/100g. This quantification was achieved using a mathematical equation derived from a calibration curve, where the relationship was represented as y = 0.0013x + 0.0498. In this equation, 'y' represented the absorbance value, and 'x' stood for the Gallic acid equivalent. The coefficient of determination (R²) for this equation was determined to be 0.999.

Estimation of total flavonoids:

The quantification of total flavonoids was carried out in accordance with the methodology outlined by Ordonez et al. in 2006¹³. In this process, 0.5ml of the sample was combined with an equal volume (0.5ml) of a 2% AlCl₃ ethanol solution. Subsequent to this mixing, the mixture was allowed to stand for a duration of one hour at room temperature. The determination of flavonoid content was achieved by measuring the absorbance at a wavelength of 420nm, utilizing a UV-visible spectrophotometer (Shimadzu UV1800). A distinct yellow color development indicated the presence of flavonoids within the sample. The quantification of total flavonoid content was expressed in terms of rutin equivalents (mg/100g) and was calculated using a mathematical equation derived from a calibration curve. This equation was represented as y = 0.0182x - 0.0222, with an associated coefficient of determination (R²) of 0.9962. Within this equation, 'y' represented the absorbance value, and 'x' corresponded to the Rutin equivalent.

Measurement of reducing power:

The assessment of the extracts' capacity to reduce iron (III) was conducted following the procedure detailed by Oyaizu¹⁴. For this evaluation, plant extracts (100µl) were combined with a phosphate buffer (2.5ml, 0.2 M, pH 6.6) and a 1% potassium ferricyanide solution (2.5 ml). This mixture was then incubated at a temperature of 50°C for a duration of 20 minutes. To the incubated mixture, aliquots of 10% trichloroacetic acid (2.5ml) were introduced. Afterward, the mixture underwent centrifugation at 3000rpm for a period of 10 minutes. Following centrifugation, the upper layer of the solution (2.5ml) was blended with distilled water (2.5ml) and a freshly prepared ferric chloride solution (0.5ml, 0.1%). Subsequent to these preparations, the absorbance of the mixture was measured at a wavelength of 700nm, employing spectrophotometer. The evaluation of reducing power was expressed in terms of ascorbic acid equivalents (AAE) per 100grams of dry material, denoted as mg/100g. The quantification was facilitated by a mathematical equation derived from a calibration curve, which was represented as y = 0.0023x - 0.0063. The coefficient of determination (R²) associated with this equation was calculated to be 0.9955. Within the equation, 'y' represented the absorbance value, while 'x' symbolized the ascorbic acid equivalent.

Determination of DPPH free radical scavenging activity:

The free radical scavenging activity of the plant samples and butylated hydroxyl toluene (BHT) as a positive control was determined using the stable radical DPPH (1,1-diphenyl-2-picrylhydrazyl)¹⁵. Aliquots (20 - 100ml) of the tested sample were placed in test tubes and 3.9 ml of freshly prepared DPPH solution (25mg L^-1) in methanol was added to each test tube and mixed. 30 min later, the absorbance was measured at 517nm (UV-visible spectrophotometer, Shimadzu UV 1800). The capability to scavenge the DPPH radical was calculated, using the following equation:

DPPH scavenged (%) = {(A_c – A_t)/A_c} x 100

Where A_c is the absorbance of the control reaction and A_t is the absorbance in the presence of the sample of the extracts. The antioxidant activity of the extract was expressed as a percentage inhibition of DPPH radicals by the extract.

Scavenging activity of ABTS radical cation:

The 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation (ABTS^.+)-scavenging activity was measured according to the method described by Re et al. 1999¹⁶. ABTS was dissolved in water to a 7 mM concentration. The ABTS radicals were produced by adding 2.45mM potassium persulphate (final concentration). The completion of radical generation was obtained in the dark at room temperature for 12–16 h. This solution was then diluted with ethanol to adjust its absorbance at 734nm to 0.70±0.02. To determine the scavenging activity, 1ml of diluted ABTS^.+ solution was added to 10ml of plant extract (or water for the control), and the absorbance at 734 nm was measured 6 min after the initial mixing, using ethanol as the blank. The percentage of inhibition was calculated by the equation:

ABTS scavenged (%) = (A_c– A_s) / A_c´ 100

Where, A_c and A_s are the absorbencies of the control and of the test sample, respectively. The antioxidant activity of the extract was expressed as percentage of inhibition of ABTS radicals by the extract.

Values are presented as the mean ± standard error mean of three replicates. The total phenolic content, flavonoid content, reducing power and radical scavenging activities of each plant extract were calculated using linear regression analysis.

RESULTS AND DISCUSSION:

Table 1 displays the total phenolic content of the various vegetables. Among the fresh vegetables, the range of total phenolic content was observed to be 77.47±3.24 –797.68±3.16 mg GAE/100g. The order of rankings, from highest to lowest content, was as follows: P. lineata> S. gilo> S. kurzii> P. ocymoides> C. colebrookeanum.

Table 1: Antioxidant properties of wild edible plants and effect of cooking

Name of the plant		Total phenolic content (mg GAE/100g DPM)	Total flavonoid content (mg RE/100g DPM)	Reducing power (mg AAE/100g DPM)	DPPH Radical scavenging activity (% of inhibition)	ABTS Radical scavenging activity (% of inhibition)
P. ocymoides	Raw	77.73±2.03	49.58±3.05	48.94±3.03	15.62±2.05	15.54±3.07
	Boiled	69.25±1.16 (-10.90%)	41.23±1.44 (-16.84%)	41.28±2.06 (-15.65%)	11.98±6.04 (-23.30%)	11.85±5.05 (-23.75%)
	Microwave cooking	83.08±2.55 (+6.88%)	54.56±2.56 (+10.04%)	53.43±3.34 (+9.17%)	19.65±4.08 (+25.80%)	18.59±7.04 (+19.63%)
C. colebrookeanum	Raw	77.47±3.24	47.20±2.06	52.07±2.49	13.99±3.07	20.11±3.06
	Boiled	68.94±1.78 (-11.01%)	40.28±1.04 (-14.66%)	44.72±1.38 (-14.11%)	9.25±2.12 (-33.88%)	16.05±2.19 (-20.19%
	Microwave cooking	80.28±1.22 (+3.62%)	51.42±3.45 (+8.94%)	57.68±2.34 (+10.77%)	17.02±4.35 (+21.66%)	24.79±1.08 (+23.27%)
S. gilo	Raw	192.12±4.07	51.47±1.05	58.40±1.16	28.29±1.06	44.78±2.09
	Boiled	167.88±2.19 (-12.61%)	44.34±1.59 (-13.85%)	51.56±1.35 (-11.71%)	22.18±2.19 (-21.59%)	39.71±4.06 (-11.32%)
	Microwave cooking	201.32±8.34 (+4.78%)	57.21±1.23 (+11.15%)	62.78±2.55 (+7.50%)	31.79±5.07 (+12.37%)	49.56±6.05 (+10.67%)
S. kurzii	Raw	98.94±1.11	47.86±1.11	55.02±4.06	7.62±1.06	12.22±2.36
	Boiled	73.55±1.09 (-25.66%)	39.82±1.44 (-16.79%)	49.16±2.32 (-10.65%)	4.32±2.17 (-43.30%)	8.01±1.29 (-34.45%)
	Microwave cooking	103.23±1.12 (+4.33%)	53.45±2.64 (+11.67%)	61.31±1.88 (+11.43%)	11.15±1.76 (+46.32%)	17.89±4.06 (+46.39%)
P. lineata	Raw	797.68±3.16	86.83±3.01	112.22±1.55	83.44±2.09	79.46±3.05
	Boiled	703.53±2.88 (11.80%)	80.43±2.09 (-7.37%)	104.88±1.18 (-6.54%)	76.39±3.07 (-8.44%)	71.32±5.06 (-10.24%)
	Microwave cooking	815.25±1.09 (+2.20%)	91.33±2.12 (+5.18%)	117.14±0.11 (+4.38%)	91.28±2.04 (+9.39%)	86.21±8.02 (+8.49%)
Range of Loss/Increase in %	Boiled	Loss (10.90-25.66)	Loss (7.37-16.84)	Loss (6.54-15.65)	Loss (8.44-43.30)	Loss (10.24-34.45)
Range of Loss/Increase in %	Microwave cooking	Increase (2.20-11.80)	Increase (5.18-11.67)	Increase (4.38-11.43)	Increase (9.39-46.32)	Increase (8.49-46.39)

Each value in the table was obtained by calculating the average of three experiments and data are presented as Mean ±Standard error of the mean (SEM).

Statistical analysis were carried out by Tukeys test at 95% confidence level and statistical significance were accepted at the p <0.05 level. The negative value within bracket indicates percentage decrease and positive value within bracket indicates the percentage increase of the test parameters.

The impact of microwave cooking was observed to result in an increase in the total phenolic content of the studied plants. Specifically, the percentage increments were as follows: P. ocymoides (6.88%), C. colebrookeanum (3.62%), S. gilo (4.78%), S. kurzii (4.33%), and P. lineata (2.20%).

In contrast, the application of boiling as a cooking method was associated with a reduction in the total phenolic content across all investigated plants. The extent of this reduction ranged from 10.90% to 25.66%. Among these plants, S. kurzii experienced the most substantial decrease, with a decline of 25.66% (Fig.1).

Among the wild edible plants studied, P. lineata displayed the highest total flavonoid content (86.83mg RE/100g), followed by S. gilo (51.47 mg RE /100g), P. ocymoides (49.58mg RE/100g), S. kurzii (47.86mg RE /100g), and C. colebrookeanum (47.20mg RE/100g) (Table 1). Microwave cooking was observed to lead to an increase in the flavonoid content in P. ocymoides (54.56mg RE/100g), C. colebrookeanum (51.42 mg RE /100g), S. gilo (57.21mg RE/100g), S. kurzii (53.45mg RE/100g), and P. lineata (91.33mg RE/100g).

Fig. 1: Total phenolic content in wild edible plants and effect of cooking

However, boiling had the opposite effect, resulting in a decrease in the flavonoid content in P. ocymoides (41.23 mg RE/100g), C. colebrookeanum (40.28mg RE/100g), S. gilo (44.34mg RE/100g), S. kurzii (39.82 mg RE /100g), and (80.43mg RE/100g) (Fig. 2).

Fig. 2: Total flavonoid content in wild edible plants and effect of cooking

Our findings indicate a significant increase (p < 0.05) in both total phenolic content and flavonoid content following microwave cooking. This outcome can potentially be attributed to the breakdown of plant cell walls induced by microwave treatment. This breakdown enhances the accessibility of polyphenols for extraction, potentially leading to the more efficient release of bound polyphenols in the microwaved samples compared to their fresh counterparts.

When vegetables undergo various cooking methods such as pressure cooking, microwaving, baking, griddling, or deep frying, variations in their antioxidant activity or scavenging capacity are observed. These variations are influenced by factors including the specific type of vegetables involved, the bioavailability of phenolic compounds, the manner in which the vegetables are prepared, and the reaction conditions utilized in the assay. These intricate dynamics collectively contribute to the fluctuations in antioxidant properties^17-19.

The reducing power (RP) of both the raw and cooked vegetables was assessed in terms of Ascorbic acid equivalent (AAE) and is presented in Table 1. Within the range of studied wild edible plants, P. lineata exhibited the highest reducing power (112.22 mg AAE /100g), followed by S. gilo (58.40 mg AAE /100g), S. kurzii (55.02 mg AAE /100g), C. colebrookeanum (52.07 mg AAE/100g), and P. ocymoides (48.94mg AAE/100g). Microwave cooking was observed to enhance the reducing power of P. lineata (4.38%), S. gilo (7.50%), S. kurzii (11.43%), C. colebrookeanum (10.77%), and P. ocymoides (9.17%). Conversely, boiling led to a reduction in the reducing ability of P. lineata (6.54%), S. gilo (11.71%), S. kurzii (10.65%), C. colebrookeanum (14.11%), and P. ocymoides (15.65%) (Fig. 3). This decline in activity attributed to boiling could be attributed to the possible decrease in ascorbic acid content. In contrast, microwave heating is presumed to better preserve active components within the cooked tissue, as indicated in previous research¹⁹.

Fig. 3: Reducing power of wild edible plants and effect of cooking

For the majority of the analyzed vegetables, our results align with this pattern. Generally, vegetables cooked using a microwave oven exhibited higher activity compared to those cooked through boiling. This phenomenon can be attributed to the fact that microwave heating doesn't stimulate the release of ascorbic acid or other antioxidants from the cooked tissue, leading to a better retention of active components.

Boiling or pressure cooking processes often lead to lixiviation, causing a reduction in the content of both total phenolics and carotenoids. In fact, the reduction can be significant, reaching 49% for total phenolics and 64% for carotenoids²⁰. This reduction occurs due to the leaching of phenolic compounds into the cooking water, alongside the formation of complex phenol-protein structures, ultimately resulting in a decrease in antioxidant activities^21-22.

Notably, certain vegetables contain higher concentrations of phenolic acids in their outer layers, which are particularly susceptible to contact with water. This exposure to water contributes to the diminishment of the antioxidant properties of these vegetables²³.

In contrast, microwave heating emerges as a method that preserves the active components within the cooked tissue¹⁹. This preservation is likely due to the fact that microwave heating, griddling, and baking processes do not stimulate the release of ascorbic acid or other antioxidants from the cooked tissue.

Our findings align with these patterns for the majority of the analyzed vegetables. Generally, the activity of vegetables cooked using a microwave oven tends to exhibit higher levels of antioxidant potential compared to those cooked through boiling. This discrepancy can be attributed to the varying effects of these cooking methods on the retention of antioxidants and active compounds within the vegetables' tissue.

Fig. 4: DPPH radical scavenging activities of wild edible plants and effect of cooking

As per the DPPH radical scavenging method, the antioxidant activity of fresh wild vegetables exhibited a descending order: P. lineata>S. gilo>P. ocymoides>C. colebrookeanum>S. kurzii (Table 1). Among all the vegetables tested, the edible portions of P. lineata exhibited the highest DPPH radical scavenging activity, displaying an inhibition rate of 83.44%. In contrast, the fruits of S. kurzii displayed the lowest activity, with a DPPH radical scavenging inhibition of 7.62%.

The DPPH radical scavenging antioxidant activity for all the investigated vegetables demonstrated a noteworthy increase (p<0.05) during microwave cooking. Specifically, the microwave cooking procedures led to increased DPPH radical scavenging activity in P. lineata (9.39%), S. kurzii (46.32%), S. gilo (12.37%), C. colebrookeanum (21.66%), and P. ocymoides (25.66%) when compared to the values observed in their fresh state.

Conversely, the application of boiling as a cooking method resulted in decreased DPPH radical scavenging activity. The reduction in scavenging activity was notable for P. lineata (8.44%), S. kurzii (43.30%), S. gilo (21.59%), C. colebrookeanum (33.88%), and P. ocymoides (23.30%) when compared to their raw forms (Fig. 4).

When evaluated using the ABTS radical scavenging method, the antioxidant activity of wild vegetables demonstrated a descending sequence: P. lineata>S. gilo>P. ocymoides>C. colebrookeanum>S. kurzii (Table 1). Among all the vegetables tested, the edible portions of P. lineata exhibited the most potent ABTS scavenging activity, showcasing an inhibitory effect of 79.46%. Conversely, the fruits of S. kurzii displayed the lowest ABTS scavenging activity, with an inhibition of 12.22%.

Boiled cooking exerted a reducing influence on the ABTS radical scavenging activity for P. lineata (10.24%), S. gilo (21.59%), P. ocymoides (23.30%), C. colebrookeanum (33.88%), and S. kurzii (43.30%), in comparison to their fresh states.

In contrast, all the investigated vegetables displayed a noteworthy increase (p<0.05) in ABTS radical scavenging antioxidant activity during microwave cooking procedures. Specifically, microwave cooking led to elevated ABTS radical scavenging activity in P. lineata (8.49%), S. gilo (10.67%), P. ocymoides (19.63%), C. colebrookeanum (23.27%), and S. kurzii (46.39%) when compared to the values observed in their fresh conditions (Fig. 5). Statistically significant variations in the total antioxidant activity were evident when comparing raw and cooked edible plants. These findings align with similar observations made by other researchers who conducted a study on antioxidants in raw and cooked green leafy vegetables^24–25.

The extent of antioxidant activity loss is contingent upon both the surface area of vegetables and the duration of their cooking. Longer cooking times tend to result in greater losses. Additionally, boiled cooking, in comparison to microwave cooking, diminishes total antioxidant activity due to the migration of antioxidants into the boiling medium²⁴.

Research indicates that microwave cooking can enhance the antioxidant activity of vegetables. This enhancement can be attributed to the inactivation of peroxidases during microwave cooking. Furthermore, another study suggests that microwave cooking either maintains or augments the antioxidant potential of vegetables by enhancing the properties of naturally occurring compounds or leading to the formation of new compounds, such as those resulting from the Maillard reaction, which possess antioxidant activity^26-27.

Fig. 5: ABTS radical scavenging activities of wild edible plants and effect of cooking

While the notion that unprocessed or raw foods, particularly vegetables, are healthier prevails, it's noteworthy that in India, cooking vegetables prior to consumption is a common practice. Understanding the optimal cooking technique becomes essential to preserve the nutritional components of vegetables. According to the findings of the present study, microwave cooking emerges as a more effective method for increasing the antioxidant activity of green leafy vegetables and other types of vegetables through the elevation of phenolics and flavonoids, surpassing alternative cooking methods.

CONCLUSION:

The results indicated that among all the vegetables studied, P. lineata consistently maintained its exceptionally high radical-scavenging capacity across all cooking conditions. The utilization of microwave cooking techniques led to notable increases in the total phenolic content, total flavonoid content, reducing power, and radical scavenging capabilities of several vegetables. Conversely, boiling emerged as a cooking method that significantly decreased the polyphenol content of the vegetables, rendering it a less favorable option for cooking the vegetables under investigation.

Our research has successfully identified effective cooking methods that preserve the antioxidant and health-promoting attributes of vegetables. The implications of these findings could potentially influence the food industry to recommend specific cooking techniques aimed at maintaining the antioxidant properties of the vegetables we consume. The study's outcomes can serve as a valuable repository of information, detailing how various cooking methods impact the antioxidant potential of different vegetables. Nevertheless, further investigations are warranted in the future to comprehensively understand the impact of cooking on the chemical efficacy of these vegetables.

CONFLICT OF INTEREST:

We state unequivocally that we have no competing interests.

ACKNOWLEDGEMENTS:

Dr. A.A. Mao Singh, Director, Botanical Survey of India, Kolkata, is grateful for giving all facilities to the authors of this research. Dr. R. Gogoi, Scientist E, Botanical Survey of India, was also instrumental in identifying the plant specimens.

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Received on 27.04.2023 Modified on 09.09.2023

Res. J. Pharmacognosy and Phytochem. 2024; 16(1):9-16.

DOI: 10.52711/0975-4385.2024.00003