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Abstract

Objective/background

Although Lepidium meyenii Walpers is recognized as a nutrient-dense root with potential benefits for older adults, its dense and fibrous texture limits direct consumption by those with reduced chewing and digestive capacity. Developing softer preparations of root crops is therefore an important strategy for improving nutritional accessibility in aging populations.

Methods

This work evaluated the role of enzymatic treatments in modifying the texture of Lepidium meyenii tissue. Three hydrolytic enzymes—cellulase, polygalacturonase, and α-amylase—were applied individually, and the resulting physicochemical attributes were compared with untreated controls.

Results

The antioxidant and antidiabetic properties of Lepidium meyenii were notably demonstrated. All enzyme applications contributed to a measurable reduction in tissue hardness. In particular, cellulase treatment induced pronounced structural changes, including enlarged and irregular pore formation, which appeared to be a major factor in texture softening.

Conclusion

These findings suggest that enzymatic modification may be a viable strategy to produce elder-friendly forms of Lepidium meyenii and similar root vegetables, enhancing their usability in dietetic products while also supporting interest in natural bioactive constituents.

Keywords

Maca elder-friendly food texture fibrous structure enzyme treatment

Introduction

The proportion of older adults in Korea is rapidly increasing, with those aged 65 and above expected to make up over one-fifth of the population by 2025.¹ Aging is commonly associated with reduced physical function and increased nutrient requirements, making access to appropriate nutrition essential for healthy aging. Root vegetables are valuable nutrient sources rich in minerals and bioactive compounds beneficial for older adults.² However, their typically fibrous and hard texture presents consumption challenges for seniors with diminished chewing ability.

Lepidium meyenii Walpers (Brassicaceae), also known as Maca, was identified by a British Broadcasting Corporation (BBC) report as one of the world's top root vegetables with potential health-promoting effects related to aging and is rich in various antioxidants such as phenolic compounds and flavonoids.^3,4 The bioactive constituents of Maca primarily include flavonoids such as quercetin and kaempferol derivatives, as well as phenolic acids including gallic acid and cinnamic acid derivatives.⁵ These compounds play significant roles in the antioxidant and anti-inflammatory properties of Maca, supporting its relevance in elder-friendly food applications.⁶ Despite these benefits, its tough texture limits direct consumption by elderly populations. The Korean Ministry of Food and Rural Affairs has established standard classifications for food hardness suitable for elders with different chewing capacities.⁷ According to the Korean Industrial Standard (KS), foods are quantitatively classified by hardness levels suitable for older adults: foods chewable by teeth (55 000-500 000 N/m²), by gums (22 000-50 000 N/m²), and by the tongue (<2000 N/m²).

Enzymatic modification using hydrolytic enzymes including cellulase, polygalacturonase, and α-amylase is an established approach to soften root vegetables by degrading cell wall components.⁸ These enzymes catalyze the breakdown of cellulose, pectin, and starch, respectively, producing texture changes that enhance palatability and digestibility. While enzyme treatments have been applied to various root crops, research on Lepidium meyenii texture modification remains limited.

The growing elderly population faces challenges in consuming nutrient-dense but texturally hard root vegetables like Lepidium meyenii, which limits their nutritional intake. This study aims to investigate the effects of cellulase, polygalacturonase, and α-amylase treatments on the texture and microstructure of Lepidium meyenii to develop elder-friendly food products. By elucidating how enzymatic modifications soften tissue hardness and alter microstructure, this research seeks to support the formulation of softer, nutritious foods tailored to the specific dietary needs of aging consumers, ultimately enhancing their food accessibility and health.

Material and Methods

Sample Preparation

Fresh Lepidium meyenii, cultivated in Hokkaido, Japan in 2022, were obtained via Rakuten (Big Country Japan Co. Ltd, Kanazawa). The botanical identity was verified by comparison with published morphological descriptions and reference images.^3,4 To ensure sample consistency, any roots exhibiting signs of spoilage were removed after assessing overall freshness. The remaining Lepidium meyenii were thoroughly rinsed under running water and subsequently segmented into uniform cubes, approximately 2 g each (dimensions: 1 cm × 1 cm × 1 cm). These prepared segments were immediately vacuum-sealed and stored at 4 °C until further analysis.

Sample Processing Method

This experiment was conducted according to Kim et al's method.⁸ To prepare test samples, fresh Lepidium meyenii (100 g each) were combined with each enzyme—cellulase, polygalacturonase, or α-amylase—with an enzyme dosage corresponding to 0.1% of the Lepidium meyenii weight. The mixtures were vacuum sealed and subjected to immersion in a water bath maintained at 50 °C for various durations (0.5, 1, 2, 3, 4, and 5 h). These enzyme-treated Lepidium meyenii samples were allocated to separate experimental groups for subsequent texture measurements. Additionally, a reference group was created using Lepidium meyenii that was processed identically but excluded any enzyme addition, serving as a control.

Analysis of Fatty Acid Profile

For the fatty acid (FA) profile analysis, the method of Aldai et al was followed as a reference.⁹ A sample weighing 20 mg of Lepidium meyenii was subjected to saponification by reacting with 3 mL of 0.5 N methanolic sodium hydroxide (NaOH) at 85 °C for 10 min. Then, 3 mL of 14% methanolic BF₃ was added to carry out methylation at the same temperature for an additional 10 min. Subsequently, 3 mL of isooctane and 5 mL of saturated NaCl solution were incorporated, followed by vigorous mixing. After phase separation, the upper isooctane layer was collected and passed through a column filled with anhydrous Na₂SO₄ for drying. The composition of FA was then determined by gas chromatography (GC) using an Agilent Technologies 7890-A system (Palo Alto, CA, USA). The injector and detector temperature were set at 225 °C and 285 °C, respectively. Identification and quantitation of FAs were achieved by comparing retention times with those of standard reference mixtures (Supelco 37-component FA methyl esters mix, Bellefonte, PA, USA).

Analysis of Mineral Profile

The method described by Seco-Gesto et al was adapted for this study.¹⁰ Approximately 0.7 g of Lepidium meyenii sample was subjected to digestion in a two-step process using 10 mL of nitric acid and 3 mL of 30% hydrogen peroxide at 200 °C. Following digestion, 25 mL of a 5% HCl solution was added to the mixture. The mineral content was then determined using inductively coupled plasma optical emission spectrometry (ICP-OES; Vista MPX, Varian, Mulgrave, Australia). The ICP-OES parameters were set as follows: forward power at 1000 W, auxiliary argon flow rate of 1.5 L/min, nebulizer argon flow at 0.9 L/min, cooling argon flow rate of 15 L/min, 2-point background correction, and an integration time of 10 s per reading with triplicate measurements for precision.

Analysis of Antioxidant Effects

The procedure was adapted from the method described by Kim and Joo.⁷ Lepidium meyenii was freeze dried at −40 °C for a duration of 72 h using a freeze dryer (model SFD-8, Daihan, Wonju, Gangwon, Korea). Once dried, the samples were ground into a fine powder and subjected to extraction with 70% ethanol for 12 h. Following extraction, the mixture was filtered through Whatman filter paper (Maidstone, Kent, UK) to obtain a clear extract, which was then used for subsequent antioxidant activity assays.

Total Polyphenol Content. The procedure was adapted from the method described by Kim and Joo.⁷ Initially, 40 µL of the extract was combined with 800 µL of Folin-Ciocalteu reagent (Sigma-Aldrich, St. Louis, MO, USA) and incubated in darkness for 5 min. Subsequently, 800 µL of a 7% (w/v) sodium carbonate solution and 360 µL of nanopure water were added to the mixture. The solution was then allowed to stand in a dark environment for 2 h to develop color. The absorbance was recorded at 760 nm employing a UV-visible spectrophotometer (T60UV, PG instruments Ltd, Lutterworth, UK). Quantification was performed using gallic acid as the calibration standard, and the results are expressed as gallic acid equivalents (GAE).

Total Flavonoid Content. The total flavonoid content was determined following the method adapted from Woisky and Salatino.¹¹ Briefly, 0.5 mL of the sample extract was combined with 1.5 mL of 95% ethanol, 0.1 mL of a 10% aluminum chloride hexahydrate solution, 0.1 mL of 1 M potassium acetate, and 2.8 mL of distilled water. The mixture was then left to react at room temperature for 40 min. Subsequently, the absorbance was read at 415 nm using a UV-visible spectrophotometer (T60UV, PG Instruments Ltd, Lutterworth, UK). Rutin served as the calibration standard for quantification, and the results are expressed as rutin equivalents (RE).

Superoxide Radical Scavenging Activity. The method by Robak and Gryglewski was followed to measure superoxide radical scavenging activity.¹² In this assay, 0.025 mL of the sample was combined with 100 µM xanthine and 60 µM nitro blue tetrazolium prepared in 0.1 M phosphate buffer (pH 7.4). Then, a xanthine oxidase solution at 0.07 U/mL was added, bringing the total volume to 1 mL. The mixture was incubated at 25 °C for 10 min. The absorbance was recorded at 560 nm using a UV-visible spectrophotometer (T60UV, PG Instruments Ltd, UK). Quercetin was employed as the reference standard.

DPPH Radical Scavenging Ability. The method described by Brand-Williams et al was utilized to evaluate DPPH radical scavenging activity.¹³ Briefly, 50 µL of the sample was combined with 2 mL of a 6 × 10⁻⁵ M solution of 2,20-diphenyl-1-picrylhydrazyl (DPPH). The absorbance initially recorded at 515 nm using a UV-visible spectrophotometer (T60UV, PG Instruments Ltd, Lutterworth, UK). After allowing the mixture to react for one hour, the absorbance was measured again to determine the percentage inhibition of DPPH radicals.

ABTS Radical Scavenging Activity. The ABTS radical cation (ABTS^•+) scavenging activity was evaluated following the approach by Höferl et al¹⁴ An antioxidant assay kit from Sigma-Aldrich (St. Louis, MO, USA) was used to measure the scavenging capacity. Briefly, 10 µL of the sample was mixed with 20 µL of myoglobin solution and 150 µL of ABTS reagent—prepared by combining 10 mL of ABTS stock and 25 µL of 3% H₂O₂. The mixture was incubated at room temperature for 10 min in the dark. The absorbance was then recorded at 405 nm using a UV-visible spectrophotometer (T60UV, PG Instruments Ltd, Lutterworth, UK). Trolox served as the reference standard, and the results are expressed as trolox equivalents (TE).

Ferric Reducing Antioxidant Power. The ferric reducing antioxidant power (FRAP) assay was conducted following the procedure of Bua-in and Paisooksantivatana.¹⁵ The FRAP reagent was freshly prepared by combining 25 mL of acetate buffer, 2.5 mL of 24,6-Tris(2-pyridyl)-s-triazine (TPTZ) solution, and 2.5 mL of ferric chloride solution. A volume of 300 µL of this reagent was pre-warmed at 37 °C, then mixed with 30 µL of distilled water and 10 µL of the test sample. The absorbance of the resulting solution was measured at 593 nm using a UV-visible spectrophotometer (T60UV, PG Instruments Ltd, Lutterworth, UK).

Reducing Power. The reducing power assay was performed following a modified version of the method by Shebaby et al¹⁶ A mixture of 2.5 mL of the sample, 2.5 mL of 200 mM sodium phosphate buffer at pH 6.6, and 2.5 mL of 1% potassium ferricyanide was prepared and incubated at 50 °C for 20 min. Subsequently, 2.5 mL of 10% trichloroacetic acid was added, and the mixture was centrifuged at 650 rpm for 10 min to separate the supernatant. Then, 2.5 mL of the supernatant was combined with 2.5 mL of distilled water and 0.5 mL of 0.1% ferric chloride solution. The absorbance of this final mixture was measured at 700 nm using a UV-visible spectrophotometer (T60UV, PG Instruments Ltd, Lutterworth, UK).

Analysis of Antidiabetes Effects

The procedure was adapted from the method described by Kim and Joo.⁷ For the analysis of antidiabetic effects, Lepidium meyenii was freeze-dried at a temperature of −40 °C for 72 h using a freeze dryer (SFD-8, Daihan, Wonju, Gangwon, Korea). After drying, the Lepidium meyenii was ground into a fine powder and extracted with 70% ethanol for a duration of 12 h. The resulting extract was then filtered through Whatman filter paper (Maidstone, Kent, UK) and subsequently used as the test sample for evaluating antidiabetic activity.

α–Glucosidase Inhibitory Activity. The α-glucosidase inhibitory activity was assessed following a method adapted from Thilagam et al¹⁶ In brief, 50 μL of the test sample was combined with 100 μL of 0.1 M phosphate buffer (pH 7.0) in a 96-well plate and incubated at 37 °C for 10 min. Subsequently, 50 μL of a 5 mM p-nitrophenyl-α-d-glucopyranoside substrate solution was added and the mixture was further incubated at 37 °C for 5 min. The enzyme activity was then determined by measuring the absorbance at 490 nm using a microplate reader (Imark, BioRad, CA, USA).

α–Amylase Inhibitory Activity. The α–amylase inhibitory activity was measured following the procedure adapted from Thilagam et al with modifications.¹⁷ Briefly, 500 μL of the sample was combined with 500 μL of 0.02 M sodium phosphate buffer (pH 6.9) containing 0.006 M sodium chloride and porcine pancreatic α-amylase at a concentration of 0.5 mg/mL. This mixture was incubated at 25 °C for 10 min. Subsequently, 500 μL of a 1% starch solution prepared in the same buffer was added, and the reaction was allowed to proceed at 25 °C for another 10 min. To terminate the enzymatic reaction, 1 mL of 3,5-dinitrosalicylic acid reagent was introduced, and the mixture was heated in boiling water for 5 min. After cooling to room temperature, 10 mL of distilled water was added to dilute the solution. The absorbance of the resulting solution was then measured at 540 nm using a UV-visible spectrophotometer (T60UV, PG Instruments Ltd, Lutterworth, UK).

Analysis of Texture Properties

Hardness. Texture properties were evaluated by performing a Texture Profile Analysis (TPA) using a TA-XT Express 20096 texture analyzer (Stable Microsystems Ltd, London, UK) to determine the hardness of enzyme-treated Lepidium meyenii samples.⁷ The test was carried out with a two-cycle compression setup, employing a cylindrical probe with a diameter of 10 mm and a load cell capacity of 25 kg. The analysis parameters were set as follows: a pretest speed of 3 mm/s, a trigger force threshold of 5 g, test and return speeds each at 3 mm/s, a compression distance of 5 mm, and a total test duration of 5 s.

Scanning Electron Microscopy. The fiber structure of the enzyme-treated Lepidium meyenii sample was examined using scanning electron microscopy (SEM). SEM imaging was conducted by directing a focused electron beam onto the sample surface. This interaction between the electrons and the sample's atoms produces signals that provide information about the surface's topography and composition. The electron beam scanned the sample in a raster pattern, and the image was generated by combining the position of the beam with the detected signal intensity.⁷

Statistical Analysis

The experimental data were subjected to one-way analysis of variance (ANOVA) using the SPSS statistical software (GraphPad Software Inc., San Diego, CA, USA). When significant differences were detected, multiple comparisons among groups were performed employing the Scheffe post-hoc test.⁷ Statistical significance was determined at a threshold of P < .05.

Results

Fatty Acid Composition

The FA profile of Lepidium meyenii is presented in Table 1, indicating the detection of 20 different FAs. The predominant FA was linoleic acid (18:2n6c; omega-6), an unsaturated FA, with an average content of 42.04 g/100 g. Following linoleic acid were α-linolenic acid (18:3n3; omega-3) and oleic acid (18:1n9c; omega-9). Saturated FAs, including palmitic acid (16:0), undecanoic acid (11:0), and stearic acid (18:0), were found in lower amounts.

Table 1.

Analyzed Fatty Acid Composition of Lepidium meyenii Walpers.

		Content (g/100 g)
Saturated fatty acid	Undecanoic acid (C_11:0)	3.52 ± 0.10
	Lauric acid (C_12:0)	0.06 ± 0.00
	Myristic acid (C_14:0)	0.46 ± 0.02
	Pentadecanoic acid (C_15:0)	0.18 ± 0.00
	Palmitic acid (C_16:0)	15.03 ± 0.22
	Margaric acid (C_17:0)	0.16 ± 0.00
	Stearic acid (C_18:0)	3.07 ± 0.05
	Arachidic acid (C_20:0)	0.36 ± 0.02
	Heneicosanoic acid (C_21:0)	0.08 ± 0.00
	Tricosanoic acid (C_23:0)	0.12 ± 0.00
	Total	23.03 ± 0.41
Unsaturated fatty acid	Palmitoleic acid (C_16:1)	0.12 ± 0.00
	Vaccenic acid (C_18:1n7c)	0.58 ± 0.00
	Oleic acid (C_18:1n9c)	16.47 ± 0.74
	Linoleic acid (C_18:2n6c)	42.04 ± 0.67
	Trans-linolenic acid (C_18:3t)	0.06 ± 0.00
	Alpha-linolenic acid (C_18:3n3)	17.21 ± 0.11
	Eicosenoic acid (C_20:1)	0.06 ± 0.00
	Eicosadienoic acid (C_20:2n6c)	0.07 ± 0.00
	Docosapentaenoic acid (C_22:5)	0.09 ± 0.00
	Total	76.97 ± 1.52
Total body fat		0.89 ± 0.03

Results are showed as mean values ± 6standard deviation in triplicate.

Mineral Composition

The mineral profile of Lepidium meyenii is presented in Table 2, where nine minerals were identified. Potassium (K) was detected as the most prevalent mineral at 1453.44 mg/100 g, followed by calcium (Ca) at 481.96 mg/100 g, phosphorus (P) at 207.32 mg/100 g, sodium (Na) at 26.26 mg/100 g, iron (Fe) at 20.05 mg/100 g, zinc (Zn) at 10.37 mg/100 g, magnesium (Mg) at 9.11 mg/100 g, copper (Cu) at 2.08 mg/100 g, and selenium (Se) at 0.01 mg/100 g.

Table 2.

Analyzed Mineral Composition of Lepidium meyenii Walpers.

	Content (mg/100 g)
Iron	20.05 ± 1.01
Magnesium	9.11 ± 0.43
Phosphorus	207.32 ± 9.12
Selenium	0.01 ± 0.00
Potassium	1453.44 ± 66.25
Sodium	26.26 ± 1.14
Zinc	10.37 ± 0.46
Copper	2.80 ± 0.09
Calcium	481.96 ± 21.30

Results are showed as mean values ± 6standard deviation in triplicate.

Antioxidant Effects

Table 3 shows that Lepidium meyenii has a total polyphenol content of 62.01 GAE mg/100 g and a total flavonoid content of 301.12 RE mg/100 g. Lepidium meyenii exhibited 50% inhibition of SOD activity at a concentration of 339.56 μg/mL. The IC₅₀ value for DPPH radical scavenging activity was 74.30 μg/mL, representing the concentration required to neutralize 50% of the DPPH free radicals. Lepidium meyenii also demonstrated notably strong ABTS radical scavenging activity and exhibited a FRAP value of 2.23 TE mmol/100 g. In addition, it showed a reducing power of 0.37 μM.

Table 3.

Analyzed Antioxidant and Antidiabetic Effects of Lepidium meyenii Walpers.

		Status
Antioxidation	Superoxide radical scavenging activity IC₅₀ (μg/mL)	339.56 ± 15.77
	DPPH radical scavenging activity IC₅₀ (μg/mL)	74.30 ± 2.61
	ABTS radical scavenging activity (TE mM/g)	0.45 ± 0.01
	Ferric reducing antioxidant power (TE mmol/100 g)	2.23 ± 0.18
	Reducing power (μM)	0.37 ± 0.01
Antidiabetes	α-Glucosidase inhibitory activity (%)	31.48 ± 1.02
Antidiabetes	α-Amylase inhibitory activity (%)	10.62 ± 0.50

Results are showed as mean values ± 6standard deviation in triplicate.

Analysis of Antidiabetes Effects

Lepidium meyenii demonstrated an α-glucosidase inhibition rate of 31.48% and an α-amylase inhibition rate of 10.62%, as shown in Table 3.

Texture Properties

Table 4 presents the texture changes observed over different treatment durations for each enzyme. Cellulase treatment for 5 h significantly reduced Lepidium meyenii hardness compared to untreated samples. Specifically, samples treated between 30 min to 1 h showed hardness values (22 000 ∼ 50 000 N/m²) compatible with chewing using gums, while treatments lasting 4 h or longer resulted in hardness (∼20 000 N/m²) suitable for tongue mastication. Polygalacturonase treatments for 3 to 4 h demonstrated hardness (22 000 ∼ 50 000 N/m²) suitable for gum chewing, whereas treatments beyond 4 h reached softness (∼20 000 N/m²) appropriate for tongue mastication. Similarly, α-amylase-treated samples for 30 min to 4 h had hardness levels (55 000 ∼ 500 000 N/m²) chewable by teeth, while those undergoing 5 or more hours softened to levels (22 000 ∼ 50 000 N/m²) manageable with gums.

Table 4.

Hardness (N/m²) of Lepidium meyenii Walpers Treated by Enzyme and Time.

Time	Enzyme			F-value(P-value)
Time	Cellulase	Polygalacturonase	α-Amylase	F-value(P-value)
0 min	138 210.20 ± 6910.51^A	138 210.20 ± 6910.51^A	138 210.20 ± 6910.51^A	0.965(.433)
30 min	108 917.75 ± 5071.48^bB	126 408.27 ± 6065.31^aAB	133 935.29 ± 5615.36^aA	15.763**(.004)
1 h	79 007.96 ± 3654.83^bC	93 004.00 ± 4555.25^aAB	99 281.19 ± 4002.04^aB	19.370**(.002)
2 h	49 336.21 ± 2238.09^cD	66 921.61 ± 3169.31^bAB	77 770.85 ± 3083.71^aC	75.408***(.000)
3 h	38 302.29 ± 1727.36^cD	49 705.14 ± 2548.05^bAB	75 145.10 ± 2811.81^aC	184.040***(.000)
4 h	19 730.61 ± 806.45^cE	33 867.58 ± 1165.57^bAB	55 567.05 ± 2525.44^aD	350.153***(.000)
5 h	6930.60 ± 318.68^cF	19 517.70 ± 811.98^bB	43 567.75 ± 1462.71^aD	1109.377***(.000)
F-value(P-value)	568.637***(.000)	5.232**(.006)	254.039***(.000)

Results are showed as mean values ± standard deviation in triplicate.

One-way ANOVA was used, and different letters in the same row (a ∼ c) and column (A ∼ F) show significant differences at *** P < .001, respectively.

Scanning Electron Microscopic Structures

The internal fibrous structure of Lepidium meyenii was examined using scanning electron microscopy to observe changes before and after enzyme treatment at the microscale (Figure 1). In contrast, the samples treated with enzymes exhibited visible alterations, including the formation of cavities, disrupted structural patterns, and more open tissue arrangements, which contributed to the softening of Lepidium meyenii. More detailed observation revealed an increase in both the size and quantity of pores within the tissue following enzyme exposure. Moreover, extended exposure time to the enzymes intensified tissue deformation and made the cellular arrangement increasingly irregular. These microstructural modifications were observed across all enzyme-treated groups when compared with the control. The heat used during enzyme treatment (around 50 °C, optimal for enzyme activity) likely caused partial cell wall degradation, leading to enlarged pore areas that enhanced enzyme penetration during the process.

Figure 1.

SEM micrograph of Lepidium meyenii Walpers treated by enzyme and time. SEM microscope filmed at 3600 x.

Discussion

Fatty Acid Composition

While unsaturated FAs are the major type present in most vegetables and considered beneficial, there remains ongoing debate about whether saturated FAs from vegetables have the same health risks as those derived from animal sources. Nevertheless, it is generally advised to moderate consumption of foods high in saturated fats. With that in mind, this study suggests that Lepidium meyenii could be a favorable option for elderly nutrition due to its low saturated fat content. Compared to other root vegetables, such as carrot—which is typically recognized as healthy for seniors due to its frequent use in elderly diets and its beneficial nutritional profile—Lepidium meyenii contains a much higher level of unsaturated FAs (76.97 g/100 g vs 17.00 g/100 g).¹⁸ Recent studies by Loba-Pasternak et al confirmed linoleic and palmitic acids as predominant FAs in Peruvian Maca roots, consistent with our findings.¹⁹ Prior research also links excessive intake of saturated fats with increased risks of myocardial infarction, high cholesterol, elevated low-density lipoprotein (LDL) cholesterol and blood pressure, as well as cancer and other chronic conditions.²⁰

Conversely, the high unsaturated FA content in Lepidium meyenii suggests it may play a role in mitigating the risk of chronic diseases, including inflammatory and autoimmune disorders. Notably, unsaturated FAs like linolenic and oleic acids are associated with reduced LDL cholesterol and elevated high-density lipoprotein (HDL) cholesterol, supporting cardiovascular health. Therefore, Lepidium meyenii could provide superior benefits compared to carrot by supplying larger amounts of these important unsaturated fats, which contribute to biological functions such as cholesterol regulation, inflammation reduction, and maintaining heart rhythm stability.

As the elderly population grows, there is increasing interest in the role of unsaturated FAs, partly due to rising dementia rates in Korea starting around age 69.²¹ Dementia is characterized by progressive memory loss, speech difficulties, and impaired spatial-temporal skills, all of which can disrupt daily functioning and behavior. Studies have shown that omega-3, −6, and −9 FAs have protective effects against dementia. Thus, understanding the FA composition, as done in this study, is valuable for developing foods tailored for healthy, active, and independent elderly adults.

Mineral Composition

Lepidium meyenii serves as an excellent dietary source for potassium, vital for cellular balance and protein/carbohydrate metabolism.²² For comparison, carrots contained Ca at 60 mg/100 g, Fe at 0.3 mg/100 g, Zn at 0.24 mg/100 g, and Mg at 69 mg/100 g.¹⁸ Carrot was chosen as a reference due to its common consumption among elderly populations and established nutrient profile.²³ The higher Ca content supports bone/dental development, enzyme synthesis, and hormone regulation; P contributes to nucleic acid/cell membrane integrity and bone mineralization²⁴; Na aids nerve signaling, muscle contraction/relaxation, and fluid and mineral balance. Fe levels indicate value as an iron supplement within safe intake limits (0.3 to 170 mg/100 g), with no health risk; Zn supports immune function, taste, and smell. Cu acts as an enzyme cofactor in energy processes; Se aids metabolism, thyroid health, oxidative protection, immunity, cognitive aging reduction, and cardiovascular risk mitigation. Mg was lower than than in carrots (69 mg/100 g), differing from other minerals. Overall, Lepidium meyenii is rich in minerals for enzyme reactions, energy production, and nerve function. With 10.2 g per 100 g, against elderly recommendations of 1.2 to 2.0 g/kg/day or higher, it shows promising potential for older populations’ nutritional needs.²⁵

Antioxidant Effects

Total Polyphenol Content. Polyphenols present in Lepidium meyenii, which are common in many plant-based foods, are widely acknowledged for their antibacterial, antiviral, anticancer, and anti-inflammatory effects.²⁶ These significant health-promoting properties have driven interest in natural products like Lepidium meyenii. The total polyphenol content of Lepidium meyenii exceeds that of white radish, which contains 53.35 mg/100 g. Moreover, plant-derived natural antioxidants such as polyphenols are gaining attention as safer alternatives to synthetic antioxidants, which have faced some controversy. Consequently, Lepidium meyenii may serve as a beneficial substitute antioxidant source due to its richness in polyphenolic compounds with potential health advantages.⁶

Total Flavonoid Content. The flavonoid content of Lepidium meyenii exceeds that of red radish, which contains 267.47 mg/100 g.²⁷ Earlier research also highlighted Lepidium meyenii's strong free radical scavenging properties linked to its high flavonoid levels. Additionally, Sandoval et al reported that Lepidium meyenii naturally contains antioxidants along with other beneficial compounds.⁵ These findings suggest that Lepidium meyenii's rich flavonoid content could contribute to inhibiting lipid peroxidation, neutralizing free radicals, and exerting anti-inflammatory effects. Moreover, Lepidium meyenii may help lower the risk and slow the progression of atherosclerosis and insulin resistance, while also supporting the maintenance of healthy blood pressure.

Superoxide Radical Scavenging Activity IC₅₀. This scavenging activity was superior to that of erycibe root, which showed an IC₅₀ of 332.29 μg/mL.²⁸ Superoxide anions, generated by the membrane-bound enzyme nicotinamide adenine dinucleotide phosphate oxidase through electron reduction of molecular oxygen, can cause significant cellular damage.¹⁶ Prolonged exposure to these harmful radicals leads to cellular deterioration, including diminished ATP production, damage to cell membranes, impaired protein synthesis, cytoskeleton disruption, and DNA degradation. Antioxidants such as vitamins, polyphenols, and flavonoids can neutralize these harmful superoxide anions, with previous research emphasizing the essential role of flavonoids. These findings suggest a positive correlation between the polyphenol and flavonoid contents in Lepidium meyenii and its SOD activity, since phenolic compounds are mainly responsible for this antioxidant effect.

DPPH Radical Scavenging Activity IC₅₀. This result suggests that Lepidium meyenii possesses moderate antioxidant capacity when compared to reference root vegetables, such as black radish (IC₅₀ of 60 μg/mL), which is widely recognized for its antioxidant properties.²⁶ The observed antioxidant activity in Lepidium meyenii may be associated with its phenolic and flavonoid contents, compounds known to play a role in free radical scavenging. These findings align with previous studies that demonstrate a direct relationship between antioxidant capacity and total phenolic content in herbs, vegetables, and fruits.

ABTS Radical Scavenging Activity. ABTS radical scavenging activity of Lepidium meyenii exceeds that of white radish, which contains 0.21 mM/g.²⁶ Our findings showed ABTS activity similar to that reported for purple Maca by Uto-Kondo et al²⁹ The ABTS^•+ are generated through the oxidation of ABTS by potassium persulfate, and these radicals are subsequently reduced by antioxidants capable of donating hydrogen atoms. The antioxidant capacity is assessed by considering both the antioxidant concentration and the limited reaction time for radical cation consumption. The heightened activity may be attributed to the phenolic compounds present in Lepidium meyenii, suggesting that these compounds contribute significantly to its potent antioxidant properties.²⁶

Ferric Reducing Antioxidant Power. The antioxidant capacity measured by the FRAP assay reflects the redox potential of antioxidant compounds.³⁰ According to Table 3, the FRAP value of Lepidium meyenii (2.23 TE mmol/100 g) surpassed that of red radish (1.96 mmol/100 g) as reported by Goyeneche et al²⁷ This difference aligns with the observed correlation between FRAP values and the levels of polyphenols and flavonoids, since phenolic compounds largely contribute to the FRAP response. Essentially, the FRAP assay is positively associated with the concentration of vitamins, polyphenols, and flavonoids, similar to the relationship seen with SOD activity.

Reducing Power. The reducing power was measured as an indicator of antioxidant capacity derived from polyphenols in the sample.³¹ Reducing power reflects the presence of reducing substances capable of converting Fe³⁺-ferricyanide complexes to their ferrous form by donating hydrogen atoms, thereby interrupting free radical chain reactions. This antioxidant activity is suggested to arise from phenolic compounds, which can neutralize free radicals through electron or hydrogen donation.

Analysis of Antidiabetes Effects

These enzymes play key roles in carbohydrate digestion by breaking down polysaccharides into glucose, impacting post-meal blood sugar levels, and their inhibition can manage glucose absorption and lower postprandial spikes.³² The α-glucosidase inhibition rate of Lepidium meyenii (31.48%) is comparable to that of lotus root (30.4%), a vegetable recognized for antidiabetic properties. Carrots exhibit antidiabetic effects due to phenolic acids and flavonoids, indicating a link between high polyphenol content and diabetes prevention in fruits and vegetables, which supports inferring a relationship between the antioxidant content and antidiabetic activity of Lepidium meyenii. Additionally, Mohamed et al confirmed α-glucosidase inhibitory activity of Maca, comparable to our findings.³³ This inhibitory effect is likely influenced by bioactive compounds in natural foods, such as glycosides, polysaccharides, steroids, and terpenoids.

Texture Properties

Texture is a critical attribute influencing the sensory value of root vegetables, especially for elderly consumers who often experience decreased chewing ability with age, making texture softness an essential feature to ensure nutrient intake.¹ Lepidium meyenii, known for its firm and fibrous texture due to high fiber content compared to other root vegetables, poses challenges for direct use as elder-friendly food and requires pretreatment softening. Besides being mineral- and vitamin-rich, softening Lepidium meyenii could enhance antioxidant intake for older adults, positively impacting the natural foods market that demands high antioxidant content.³⁴ However, studies examining Lepidium meyenii texture quality following various pretreatments remain limited. This study explored texture modification of Lepidium meyenii tailored for elderly users with varying physical characteristics through enzymatic treatment using three enzymes: cellulase, polygalacturonase, and α-amylase.

Cellulase, a heat-stable glycosyl hydrolase optimal at 50 to 55 °C, is widely used in processing root vegetables for texture softening due to its ability to cleave bonds between carbohydrates and associated molecules. This enzymatic breakdown of cellulose and related polysaccharides improves functional properties, making cellulase a promising agent for softening rigid vegetables like Lepidium meyenii. The study's texture profile analysis supports cellulase as an effective method for producing soft root vegetable products, potentially expanding dietary options for elderly individuals with chewing difficulties. Therefore, these findings could positively influence the elder-friendly food sector by offering Lepidium meyenii with texture variants catering to diverse chewing abilities

Polygalacturonase facilitates root vegetable softening by gradually modifying pectin structures. Though extensively studied in carrots, radishes, and beets, its application to Lepidium meyenii has been rarely reported.¹ This study extended prior work on cellulase by incorporating polygalacturonase treatments. These findings suggest polygalacturonase's promising role in adjusting Lepidium meyenii hardness to accommodate various elderly chewing capacities and support its use in developing elder-friendly food products.

α-Amylase, alongside cellulase and polygalacturonase, emerges as a viable softening agent to promote Lepidium meyenii consumption among elderly populations by offering softer product options. Given hardness is a vital texture parameter for elder-friendly foods, this complementary hardness data reinforces enzyme treatment as a key process in modifying root vegetable texture. In summary, the study effectively identified enzyme treatments that soften Lepidium meyenii without negatively impacting its structural properties, enhancing its suitability for elder-friendly food applications. The natural fibrinolytic enzymes employed demonstrated beneficial effects on Lepidium meyenii's fiber composition, providing foundational data for the development of texture-modified root vegetable products. With the global rise in elderly demographics, enzymatic softening strategies present practical solutions to improve food accessibility and choice for elderly consumers, both in institutional settings and the broader marketplace. However, variability in elderly physiological conditions necessitates further foundational research to optimize enzyme selection, treatment parameters, and processing conditions. Future studies should consider raw material characteristics, treatment duration and temperature, and interaction with other food components to achieve targeted textural results for elder-friendly foods.

Scanning Electron Microscopic Structures

The untreated Lepidium meyenii samples displayed densely packed tissues without noticeable pores, indicating well-preserved and organized cellular integrity.³⁵ This structural loosening correlates to the reduction in hardness seen in Lepidium meyenii. Comparable changes have been reported in prior research involving cellulase treatment on carrots.³⁶ Similar to Paleekui et al's transglutaminase-agar soy gel softening approach, enzymatic treatment enables texture modification suitable for elderly consumers.³⁷ Overall, the results here demonstrate that enzymatic treatment effectively aids in softening Lepidium meyenii. Notably, among the enzymes tested, cellulase treatment produced the most significant increase in both pore size and number, resulting in pronounced disruption of the internal tissue structure. This structural imbalance clearly associates with the observed decrease in texture hardness.

Meanwhile, this study has several limitations. First, it used Lepidium meyenii from a single harvest and region, limiting generalizability across varieties and environments. Second, in vitro assays and instrumental texture analysis were employed without in vivo validation, sensory tests, or elderly consumer trials, potentially overestimating physiological benefits. Processing conditions were also restricted to fixed enzyme types, temperature, and times, excluding variables like pH or combined treatments. Future research should test diverse samples, conduct direct comparisons with other roots, and include clinical studies with elderly participants to confirm efficacy and acceptability.

Conclusion

This study demonstrated that enzyme-treated samples exhibited improved texture characteristics. Specifically, the enzymes utilized in this research—cellulase, polygalacturonase, and α-amylase—significantly softened the hardness of the raw material compared to the untreated control. These findings suggest that enzyme treatment can serve as an effective method to soften root vegetables, acting as a beneficial pretreatment step. The application of enzymes is valuable not only for reducing cooking time and energy consumption but also for enhancing the ease of chewing, particularly for elderly individuals experiencing dental challenges. In essence, enzymatic softening has the potential to create Lepidium meyenii products optimized for varied textures, catering to those with mastication difficulties such as the elderly. Furthermore, producing softer Lepidium meyenii can support elderly consumers in meeting their antioxidant intake goals even with smaller portion sizes. Utilizing enzymes to enhance the texture and flavor of Lepidium meyenii may transform the perception of root vegetables, facilitating their consumption without difficulty. These insights can advance the elder-friendly food sector by highlighting the beneficial qualities of root vegetables like Lepidium meyenii and providing relevant information on natural antioxidants which are increasingly valued by older consumers. The implications of this research extend beyond care home environments, aiming to improve accessibility for healthy, active elderly individuals purchasing from general markets. Additionally, the Lepidium meyenii market could expand through consumer promotion initiatives and increased demand, encouraging farmers to engage more confidently with the public market. Nevertheless, further detailed analysis of fiber modifications during enzymatic treatment and additional studies are required to successfully implement this technology in the food industry. It is also critical to define sensory softness parameters that are appropriate and perceptible to elderly consumers. Therefore, continued research focusing on sensory evaluations and establishing standards will be essential to gain elderly acceptance and to support guidelines for elder-friendly foods.

Footnotes

Acknowledgements

The authors declare no acknowledgements.

ORCID iD

Dah-Sol Kim

Ethical Approval

Ethical approval is not applicable for this article.

Statement of Informed Consent

There are no human subjects in this article and informed consent is not applicable.

Funding

This research was supported by a grant of the FoodTech RnD Center Development and Support Program through the Gyeongbuk Technopark(GBTP) funded by GYEONGSANGBUK-DO and Pohang city(GBTP2023129001), by a grant of the High Value-added Food Technology Development Program through the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture and Forestry(IPET) funded by the Ministry of Agriculture, Food and Rural Affairs(MAFRA, RS-2024-00403998 and RS-2024-00403987), by a grant of the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture and Forestry(IPET) through Agriculture and Food Convergence Technologies Program for Research Manpower development Program, funded by Ministry of Agriculture, Food and Rural Affairs(MAFRA, RS-2024-00402136).

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data Availability

The authors confirm that the data supporting of this study are available within the article.

Statement of Human and Animal Rights

This article does not contain any studies with human or animal subjects.

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Texture Properties of Lepidium meyenii Walpers for the Elderly Base on Enzyme Treatment

Abstract

Objective/background

Methods

Results

Conclusion

Keywords

Introduction

Material and Methods

Sample Preparation

Sample Processing Method

Analysis of Fatty Acid Profile

Analysis of Mineral Profile

Analysis of Antioxidant Effects

Analysis of Antidiabetes Effects

Analysis of Texture Properties

Statistical Analysis

Results

Fatty Acid Composition

Mineral Composition

Antioxidant Effects

Analysis of Antidiabetes Effects

Texture Properties

Scanning Electron Microscopic Structures

Discussion

Fatty Acid Composition

Mineral Composition

Antioxidant Effects

Analysis of Antidiabetes Effects

Texture Properties

Scanning Electron Microscopic Structures

Conclusion

Footnotes

Acknowledgements

ORCID iD

Ethical Approval

Statement of Informed Consent

Funding

Declaration of Conflicting Interests

Data Availability

Statement of Human and Animal Rights

References