Characterization, antioxidant activity, and mineral profiling of Auricularia cornea mushroom strains

Abstract

Background
Mushrooms are considered as next-generation healthy food components. Owing to their low-fat content, high-quality proteins, dietary fiber, and rich source of nutraceuticals. They are ideally preferred in formulation of low-caloric functional foods. In this view, the breeding strategies of mushroom Auricularia cornea (A. cornea) focusing on high yield and higher quality with rich nutritional values and health benefits are still needed.

Materials and methods
A total of 50 strains of A. cornea were used to analyze the bio efficiency and the time required for fruiting body formation following the cultivation experiment. The calorimetric method was used to evaluate the antioxidant activity and quantify the crude polysaccharides and minerals content thereafter.

Results
The results showed that the time required for fruiting body formation and biological efficiency varied significantly among the selected strains. Noticeably, the wild domesticated strain Ac13 of A. cornea mushroom showed the shortest fruit development time (80 days). Similarly, the hybrid strains including Ac3 and Ac15 possessed the highest biological efficiency (82.40 and 94.84%). Hybrid strains Ac18 (15.2%) and cultivated strains Ac33 (15.6%) showed the highest content of crude polysaccharides, while cultivated strains Ac1 and Ac33, demonstrated the highest content of total polysaccharides in the fruiting body (216 mg. g⁻¹ and 200 mg. g⁻¹). In the case of mineral content, the highest zinc contents were observed from the cultivated strain Ac46 (486.33 mg·kg⁻¹). The maximum iron content was detected from the hybrid strain Ac3 (788 mg·kg⁻¹), and the wild domesticated strain Ac28 (350 mg·kg⁻¹). The crude polysaccharides of the A. cornea strain showed significant antioxidant potential, and the ability of Ac33 and Ac24 to scavenge DPPH radicals and ABTS, which was significantly improved compared to other strains, respectively. Principal component analysis was applied to examine the agronomic traits and chemical compounds of various strains of A. cornea mushrooms. The results revealed that cultivated, wild domesticated, and hybrid strains of A. cornea exhibited distinct characteristics in terms of growth, yield, and nutritional properties.

Conclusion
The crude polysaccharides from A. cornea mushroom strains act as natural antioxidants, the wild, hybrid, and commercial A. cornea mushroom strains can achieve rapid growth, early maturation, and high yields. The evaluation of biochemical indexes and nutritional characteristics of strains with excellent traits provided a scientific basis for initiating high-quality breeding, provided germplasm resources for the production of “functional food” with real nutritional and health value.

Full text

Frontiers in Nutrition 01 frontiersin.org
Characterization, antioxidant
activity, and mineral profiling of
Auricularia cornea mushroom
strains
AsifAliKhan
1,2†, Li-XinLu
1†, Fang-JieYao
1,2*, MingFang
1,
PengWang
3, You-MinZhang
4, Jing-JingMeng
1, Xiao-XuMa
2,
QiHe
2, Kai-ShengShao
2, Yun-huiWei
5* and BaojunXu
6*
1 College of Horticulture, Jilin Agricultural University, Changchun, China, 2 International Cooperation
Research Center of China for New Germplasm Breeding of Edible Mushrooms, Jilin Agricultural
University, Changchun, China, 3 Institute of Economical Plants Research, Academy of Agricultural
Science of Jilin Province, Gongzhuling, China, 4 College of Forestry and Grassland, Jilin Agricultural
University, Changchun, China, 5 Jiangxi Academy of Agricultural Sciences Nanchang, Nanchang, China,
6 Food Science and Technology Program, Department of Life Sciences, BNU-HKBU United International
College, Zhuhai, China
Background: Mushrooms are considered as next-generation healthy food
components. Owing to their low-fat content, high-quality proteins, dietary fiber,
and rich source of nutraceuticals. They are ideally preferred in formulation of
low-caloric functional foods. In this view, the breeding strategies of mushroom
Auricularia cornea (A. cornea) focusing on high yield and higher quality with rich
nutritional values and health benefits are still needed.
Materials and methods: A total of 50 strains of A. cornea were used to analyze
the bio eciency and the time required for fruiting body formation following
the cultivation experiment. The calorimetric method was used to evaluate the
antioxidant activity and quantify the crude polysaccharides and minerals content
thereafter.
Results: The results showed that the time required for fruiting body formation and
biological eciency varied significantly among the selected strains. Noticeably,
the wild domesticated strain Ac13 of A. cornea mushroom showed the shortest
fruit development time (80 days). Similarly, the hybrid strains including Ac3 and
Ac15 possessed the highest biological eciency (82.40 and 94.84%). Hybrid strains
Ac18 (15.2%) and cultivated strains Ac33 (15.6%) showed the highest content of
crude polysaccharides, while cultivated strains Ac1 and Ac33, demonstrated the
highest content of total polysaccharides in the fruiting body (216 mg. g−1 and
200 mg. g−1). In the case of mineral content, the highest zinc contents were
observed from the cultivated strain Ac46 (486.33 mg·kg−1). The maximum iron
content was detected from the hybrid strain Ac3 (788 mg·kg−1), and the wild
domesticated strain Ac28 (350 mg·kg−1). The crude polysaccharides of the A.
cornea strain showed significant antioxidant potential, and the ability of Ac33
and Ac24 to scavenge DPPH radicals and ABTS, which was significantly improved
compared to other strains, respectively. Principal component analysis was applied
to examine the agronomic traits and chemical compounds of various strains of A.
cornea mushrooms. The results revealed that cultivated, wild domesticated, and
hybrid strains of A. cornea exhibited distinct characteristics in terms of growth,
yield, and nutritional properties.
Conclusion: The crude polysaccharides from A. cornea mushroom strains act
as natural antioxidants, the wild, hybrid, and commercial A. cornea mushroom
OPEN ACCESS
EDITED BY
Yajie Zou,
Chinese Academy of Agricultural Sciences,
China
REVIEWED BY
Rui-Heng Yang,
Shanghai Academy of Agricultural Sciences,
China
Jing-Kun Yan,
Dongguan University of Technology, China
*CORRESPONDENCE
Fang-Jie Yao
yao@aliyun.com
Yun-hui Wei
weiyh@126.com
Baojun Xu
baojunxu@uic.edu.cn
†These authors have contributed equally to this
work
RECEIVED 16 February 2023
ACCEPTED 19 May 2023
PUBLISHED 19 June 2023
CITATION
Khan AA, Lu L-X, Yao F-J, Fang M, Wang P,
Zhang Y-M, Meng J-J, Ma X-X, He Q, Shao K-S,
Wei Y-h and Xu B (2023) Characterization,
antioxidant activity, and mineral profiling of
Auricularia cornea mushroom strains.
Front. Nutr. 10:1167805.
doi: 10.3389/fnut.2023.1167805
COPYRIGHT
© 2023 Khan, Lu, Yao, Fang, Wang, Zhang,
Meng, Ma, He, Shao, Wei and Xu. This is an
open-access article distributed under the terms
of the Creative Commons Attribution License
(CC BY). The use, distribution or reproduction
in other forums is permitted, provided the
original author(s) and the copyright owner(s)
are credited and that the original publication in
this journal is cited, in accordance with
accepted academic practice. No use,
distribution or reproduction is permitted which
does not comply with these terms.
TYPE Original Research
PUBLISHED 19 June 2023
DOI 10.3389/fnut.2023.1167805

Khan et al. 10.3389/fnut.2023.1167805
Frontiers in Nutrition 02 frontiersin.org
strains can achieve rapid growth, early maturation, and high yields. The evaluation
of biochemical indexes and nutritional characteristics of strains with excellent
traits provided a scientific basis for initiating high-quality breeding, provided
germplasm resources for the production of “functional food” with real nutritional
and health value.
KEYWORDS
Auricularia cornea, wild mushroom, anti-oxidant activity, minerals, polysaccharides
Introduction
Mushrooms are the only treasure trove of biologically active
metabolites that are extremely rich in high-quality carbohydrates,
minerals, proteins, and dietary ber (1, 2). Under the current world
scenario, people eagerly await novel natural, non-toxic functional
foods that provide nutritional, and medicinal value (3). With their
unique aroma, mushrooms become a delicious food, a step ahead of
other natural resources.
Mushroom polysaccharides are considered suitable biological
response regulators because of their wide range of health benets (4,
5). Among all mushroom-derived substances, polysaccharides have
been shown to have potential biological activities, including anti-
inammatory, antioxidant, anticancer, antitumor, and signicant
eects on innate and adaptive immunity (6). One of the eective
bioactive compounds of edible fungi is polysaccharides, and another
important feature of mushroom polysaccharides is their potential to
scavenge free radicals (7, 8). Prior studies revealed that free radicals
are the key factor behind several chronic diseases, including
neurological disorders, cancer, arthritis, diabetes, and others (9).
Although many synthetic antioxidants such as butylated
hydroxyanisole, tert-butyled hydroxyquinine, and butylated
hydroxytoluene are readily available in the market, the main concerns
are increasing about the safety of these synthetic products used in
conventional foods. e regular intake of a substance has been found
to have detrimental eects on the health of individuals, and prolonged
utilization may result in severe adverse reactions. In this regard,
mushroom polysaccharides may be recommended as a good
alternative to the food industry as a novel potential antioxidant and
low-toxicity alternative.
Auricularia cornea is a medicinal and edible mushroom. It belongs
to the fungi Basida, Auriculariaceae, mainly distributed in China,
Korea and other East Asian countries (10). Auricularia is the fourth
most widely cultivated mushroom worldwide and a popular ingredient
in Chinese cuisine and medicine. Fungus is one of the most widely
cultivated mushrooms in China (11). According to the China Edible
Mushroom Association, the annual production of A. auricularia and
A. cornea reached 75.2 million tons and 16.9 million tons, respectively,
in 2017 (12). It is also cultivated in other parts of the world. e
advantage of A. cornea mushroom is its long shelf life (13). Due to its
ability to undergo desiccation, this particular species presents a viable
option for growers seeking to propagate mushrooms in contrast to
alternative varieties (14). A. cornea is a low-calorie food that is rich in
nutrients including good source of complex carbohydrates, low-fat
source of protein, B vitamins, including riboavin, niacin, and
pantothenic acid, minerals such as iron, potassium, and phosphorus,
polysaccharides, and consumed in moderation as part of a balanced
diet (11). ough the determination of amino acids is important for
assessing the nutritional value of a food or dietary supplement, it may
not always benecessary in studies of A. cornea as it is already been
shown to bea good source of protein, containing all essential amino
acids (15). erefore, wefocused on other aspects of its nutritional
composition, such as its mineral content, carbohydrate content, or
antioxidant activity, rather than determining the amino acid prole.
e mineral content and antioxidants of A. cornea can help determine
its potential as a dietary supplement for maintaining optimal health,
reduction of oxidative stress and inammation in the body. However,
the polysaccharides, minerals, and antioxidant properties of A. cornea
have not been studied using many germplasm resources. erefore,
this study focused on the time required for fruiting body formation,
biological eciency, polysaccharide content, antioxidant activity, and
mineral element content of 50 A. cornea mushroom strains from
China and Japan and newly developed A. cornea varieties.
Materials and methods
Mushroom strains
In this study, a total of 50 strains of A. cornea were used (listed in
Table1). Among these strains, 14 commercial cultivated strains were
obtained from distinct regions of China, namely Sichuan Academy of
Agricultural Sciences, Zhangzhou Comprehensive Experimental
Station, College of Horticulture at Jilin Agricultural University, as well
as from Japan. Furthermore, the study also included 18 wild A. cornea
strains from ve dierent provinces in China, namely Jiaohe City, Jilin
Province; Yitong City, Jilin Province; Chengzijie Town, Jiutai City, Jilin
Province, Jilin Agricultural University Campus, Changchun City, Jilin
Province, Xiamafang Ruins Park, Nanjing City, Jiangsu Province; East
bank of West Lake, Hangzhou City, Zhejiang Province; Dashushan
Forest Park, Hefei City, Anhui Province; Tongbai County Buddhist
College, Henan Province, as well as strains from Japan. In addition,
the study involved 14 hybrid A. cornea strains.
Cultivation experiment
Mix the pre-wet sawdust substrate (78%) with wheat bran (20%),
CaCO3 (1%), and CaSO4 (1%). Adjust the water content of the sawdust
mixture to about 55 to 60%. Each polyethylene bag (height 30 cm,
diameter 10 cm) was lled with 0.5 kg sawdust-based substrate,
sterilized (121°C, 120 min), and then inoculated with 4 g/bag of

Khan et al. 10.3389/fnut.2023.1167805
Frontiers in Nutrition 03 frontiersin.org
TABLE1 List of Auricularia cornea strains.
Strains Name of strains Source of strains
AC1 Ya College of Horticulture, Jilin Agricultural University (Cultivated Strains)
AC2 Ap18 Sichuan Academy of Agricultural Sciences (Cultivated Strains)
AC3 Ac3 Hybrid strain
AC4 Ap17 Sichuan Academy of Agricultural Sciences (Cultivated Strains)
AC5 Ac5 Hybrid strain
AC6 Ac6 Hybrid strain
AC7 Ac7 Hybrid strain
AC8 Ac8 Hybrid strain
AC9 Ac9 Hybrid strain
AC10 Ac10 Hybrid strain
AC11 Ac11 Hybrid strain
AC12 Ac12 Hybrid strain
AC13 TB Paulownia tree (wild strain), Tongbai County Buddhist College, Henan Province
AC14 Ac14 Hybrid strain
AC15 Ac15 Hybrid strain
AC16 Ac16 Hybrid strain
AC17 Ac17 Hybrid strain
AC18 Ac18 Hybrid strain
AC19 Ac19 Hybrid strain
AC20 Ac20 Hybrid strain
AC21 Ac21 Hybrid strain
AC22 A406 Chinese tallow tree (wild strain), Dashu Mountain Forest Park, Hefei, Anhui
AC23 A407 Chinese tallow tree (wild strain), Dashu Mountain Forest Park, Hefei, Anhui
AC24 A408 Chinese tallow tree (wild strain), Dashu Mountain Forest Park, Hefei, Anhui
AC25 A409 Chinese tallow tree (wild strain), Dashu Mountain Forest Park, Hefei, Anhui
AC26 A412 Plane tree (wild strain) on the east bank of West Lake, Hangzhou City, Zhejiang Province
AC27 Ac27 (wild strain) Hangzhou City, Zhejiang Province
AC28 A414 Plane tree (wild strain) in Xiamafang Ruins Park, Nanjing City, Jiangsu Province
AC29 A415 Plane tree (wild strain) in Xiamafang Ruins Park, Nanjing City, Jiangsu Province
AC30 A154 Pagoda tree (wild strain) Jilin Agricultural University, Changchun City, Jilin Province
AC31 Ac31 Hybrid strain
AC32 A450 Sophora japonicus (wild strain), Chengzijie Town, Jiutai City, Jilin Province
AC33 L31 Sichuan Academy of Agricultural Sciences (Cultivated Strains)
AC34 Purple Sichuan Academy of Agricultural Sciences (Cultivated Strains)
AC35 CR5 Zhangzhou Comprehensive Experimental Station (Cultivated Strains)
AC36 Zha10/ Zhangzhou Comprehensive Experimental Station (Cultivated Strains)
AC37 AY13 Sichuan Academy of Agricultural Sciences (Cultivated Strains)
AC38 A448 Acacia tree in Yitong, Jilin Province (wild strain)
AC39 A449 Acacia tree in Yitong, Jilin Province (wild strain)
AC40 Chuan Er 4 Sichuan Academy of Agricultural Sciences (Cultivated Strains)
AC41 Ac41 (wild strain) of Japan
AC42 Ac42 (wild strain) of Japan
AC43 Ac43 (wild strain) of Japan
AC44 Ac44 From Japan (Cultivated Strains)
(Continued)

Khan et al. 10.3389/fnut.2023.1167805
Frontiers in Nutrition 04 frontiersin.org
prepared spawn. Inoculation bags were kept in the spawning chamber
under dark conditions (temperature 25 ± 1°C, relative humidity 80%).
When the mycelium was fully colonized, transfer the bags to the
growing chamber (20 ± 2°C, relative humidity > 90%) to stimulate
primordium formation. e fruiting bodies were then harvested by
twisting method with clean hands for further analysis when fully
grown to reveal waveform edge (16).
Evaluation of agronomic traits
e agronomic characteristics enlisted as the time required for
fruiting body formation and biological eciency. e total number of
days from inoculation bag to harvest fruiting bodies. Harvested
fruiting bodies from the rst and second ushes were weighed in fresh
form for analysis of biological eciency. Bioeciency is the ratio of
weight (g) of fresh fruiting body/dry weight of substrate (g), expressed
as a percentage.
Extraction of crude polysaccharides
According to the method proposed by Cai etal. (17) and Skalicka-
Wozniak etal. (18), crude polysaccharides were extracted and puried
from A. cornea strains and slightly modied. Five grams of dry powdered
sample was extracted thrice with 200 mL hot water (80°C) for 3 hours.
e water extract was ltered with ber gauze, combined and then
adjusted the volume up to 50 mL. Aerward, 150 mL of chilled ethanol
(96%) was added and placed in a refrigerator at 4°C overnight to induce
precipitation. Aer centrifugation (15,000 rpm, 6 min) the precipitate
was collected, washed with ethanol, dried in the oven at 45°C and then
grinded with a pestle and mortar for further analysis. e following
equation has been used to measure the crude polysaccharide yield.
Yield (%) = m1/m2 × 100%, w here m1 is the weight of crude
polysaccharide, and m2 is the weight of A. cornea powder.
Total polysaccharides
e total polysaccharide content in crude polysaccharides
obtained from the fruiting body of the A. cornea strain was determined
by phenol-sulfuric acid method (18). An equal weight of 1 mg sample
of crude polysaccharide dissolved in 10 mL sterilized water. en, mix
1 mL of this solution with 1 mL of phenol solution (5%) and 5 mL of
concentrated sulfuric acid. e mixture was kept in the dark shaker at
25°C for 30 min, and measure the absorbance at 490 nm with a
spectrophotometer. e polysaccharide content of A. cornea strains
was determined by utilizing the glucose standard curve to calculate
the total amount. Wethen set up nine glucose solutions from dierent
sources, each with a dierent concentration of (1 mg·mL
−1
) glucose
stock solution (i.e., (20, 40, 60, 80, 100, 120, 140, 160, and 180 μL) in
a 10 mL centrifuge tube, adjust the volume to 2 mL by distilled water,
then add 1 mL of 5% phenol solution and 5 mL of concentrated
sulfuric acid, and repeat the same steps as above.
Mineral quantification
e minerals present in the fruiting bodies of the A. cornea
mushroom strain were measured using the method of (19) (cite the
reference). e fruiting body samples are oven-dried at 35°C for 24 h
and ground into a powder that can pass through a 1 mm sieve.
Weighted 1 g of mushrooms in each sample to determine the mineral
content. Aerward, “wet” digestion with a 3:1 mixture of nitric and
perchloric acid. Finally, zinc, copper, manganese, and iron in solution
were quantied using an atomic absorption spectrometer (19).
Determination of antioxidant activity
DPPH radical scavenging using the method described by (20) was
performed by vigorously mixing 2 mL of crude polysaccharide
solution (0.25, 0.50, 0.75, 1.00, 1.25, and 1.50 mg/mL) and 2 mL of
DPPH solution (0.2 mmol/L) and kept in the dark for 30 min and 2 mL
of absolute ethanol solution was used as a control. Vitamin C is used
as a standard and is formulated at the same concentration as crude
polysaccharide solutions. A spectrophotometer is used to calculate
absorbance at 517 nm. e following equation determines the free
radical scavenging eect of DPPH:
Scavenging rate (%) = (Ablank − Asample)/Ablank × 100.
A blank represents the absorbance of the control solution (no
sample), while A sample represents the absorbance of the test sample.
ABTS radical scavenging assay
Free radical scavenging activity of crude polysaccharides was
determined using the ABTS radical cation (ABTS+) test, a slightly
modied Binsan’s method (17). e reaction of 7 mM ABTS solution
with 2.45 mM potassium persulfate yields ABTS+, which was kept at
room temperature for 16 h in the dark. At 734 mM, dilute the ABTS+
solution with ethanol to obtain an absorbance of 0.70 ± 0.02. Applied
TABLE1 (Continued)
Strains Name of strains Source of strains
AC45 Chuan Er 1 Sichuan Academy of Agricultural Sciences (Cultivated Strains)
AC46 781 Sichuan Academy of Agricultural Sciences (Cultivated Strains)
AC47 Yellow Ear. 10 Sichuan Academy of Agricultural Sciences (Cultivated Strains)
AC48 Ap6 Catalpa tree (wild strain), Jiaohe City, Jilin Province
AC49 Ap7 Catalpa tree (wild strain), Jiaohe City, Jilin Province
AC50 Ap15 Sichuan Academy of Agricultural Sciences (Cultivated Strains)

Khan et al. 10.3389/fnut.2023.1167805
Frontiers in Nutrition 05 frontiersin.org
1 mL of crude polysaccharide solution samples at dierent
concentrations (0.25, 0.50, 0.75, 1.00, 1.25, and 1.50 mg/mL) to 3.9 mL
of ABTS+ solution and mix vigorously. e absorbance at 734 nm was
measured aer 6 min of reaction at room temperature (17, 21).
Statistical analysis
Data were analyzed using a well-known statistical method: Fisher
Analysis of Variance (ANOVA). Treatment means were compared
using the Least Signicant Dierence (LSD) test at the 5%
probability level.
Results and discussion
Evaluation of agronomic traits
The biological efficiency of A. cornea, including the results
of the fruiting bodies’ maturation period from the spawning
stage to the point of harvest were described in Table 2. The
shortest time of matured fruiting bodies of the A. cornea
mushroom strain was recorded from wild strains Ac13 (80 days)
and A24 (90 days). In comparison, the duration of the cultivated
strain Ac44 was extended (166 days). The number of days of
maturity of fruiting bodies of cultivated, wild and hybrid strains
ranged from spawning to harvesting fruiting bodies
(166–80 days).
e time to complete fruiting bodies recorded from cultivated
A. cornea strains was more than 90 days and longer for wild strains
compared to cultivated strains (16). is study reports the
attainment of the shortest duration for the completion of fruiting
bodies from wild and domesticated strains, representing a novel
nding. (i.e., Ac13 and Ac24). e variances in biological eciency
among A. cornea strains, including cultivated, wild, and hybrid
varieties, have been observed. e hybrid strain Ac15 showed the
highest biological eciency (94.84%), while the wild strain Ac27
indicted the lowest biological eciency (0.92%). e biological
eciency of A. cornea strains ranged from (94.84–0.986%) as
shown in Table2.
TABLE2 Total number of days for the maturity of fruiting bodies and biological eciency of A. cornea strains.
Strains Maturity of
fruiting bodies in
days
Biological
eciency
Strains Maturity of
fruiting bodies in
days
Biological
eciency
AC1 93±2vw 62.26±1.6cde AC26 105±7pqrstu 16.57±3.3vwxy
AC2 103±4qrstu 63.22±4.1cde AC27 145±6cd 0.986±0.2
AC3 99±5stuvw 82.40±4.2bAC28 105±4pqrstu 17.59±2.6uvwx
AC4 110±8nopqr 20.30±1.1stuvwx AC29 116±4klmno 7.946±0.5yz
AC5 115±4lmnop 14.69±1.3wxyz AC30 126±5fghij 32.73±2.6klmno
AC6 121±4ijklm 7.400±0.4zAC31 104±3qrstu 35.92±0.3jklmn
AC7 155±2bc 2.333±0.3 AC32 121±4ijklm 6.946±0.8z
AC8 102±2rstuv 20.80±0.7rstuvwx AC33 103±3rstuv 29.09±3.6nopqrs
AC9 113±4mnopq 2.333±0.2 AC34 156±3ab 23.60±3.1pqrstuv
AC10 154±6bc 1.426±0.1 AC35 118±5jklmn 19.82±7.1tuvwx
AC11 98±103tuvw 63.73±5.1cde AC36 110±4monpr 48.66±6.7fgh
AC12 121±3hijklm 29.02±2.4nopqrs AC37 126±4fghijk 65.06±2.7cd
AC13 80±3x29.85±1.8lmnopq AC38 131±8fghi 22.24±5.2qrstuvw
AC14 108±5opqrst 28.60±3.3nopqrst AC39 134±7ef 8.013±1.6yz
AC15 105±11pqrstu 94.84±5.3aAC40 100±2rstuv 70.27±4.7c
AC16 103±5rstu 37.12±0.8ijklmno AC41 136±4def 16.96±3.7uvwx
AC17 142±7de 38.16±2.2ijklm AC42 126±6fghijk 7.106±1.6z
AC18 116±6klmno 18.29±1.9uvwx AC43 131±4fgh 21.47±3.5qrstuvwx
AC19 123±4ghijkl 25.63±3.8opqrstu AC44 166±4a57.33±11.8def
AC20 161±8ab 17.77±2.6uvwx AC45 106±5pqrstu 55.48±8.1ef
AC21 104±4qrstu 13.09±1.2xyz AC46 109±4nopqrs 29.43±6.8mnopqr
AC22 132±8fg 28.67±0.6nopqrst AC47 109±6nopqr 32.27±3.2klmop
AC23 97±5uvw 38.61±3.6ijkl AC48 101±2rstuv 13.73±1.7wxyz
AC24 90±3wx 52.95±4.2fg AC49 118±9jklmn 39.33±0.8ijk
AC25 107±98opqrstu 42.03±1.8hij AC50 103±6qrstu 45.86±7.5ghi
Values with no letter in common in each column are signicantly dierent (p < 0.05) (means ± SD, n = 3).

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Frontiers in Nutrition 06 frontiersin.org
Crude polysaccharide content
e crude polysaccharide content of cultivated, wild and hybrid
A. cornea strain was thoroughly investigated. Crude polysaccharides
extracted from the fruiting bodies of the A. cornea strain range from
15.64–0.63% (Figure 1). e cultivated A. cornea strain Ac33
demonstrated the highest crude polysaccharide content (15.64%).
While the Japanese wild strain Ac43 indicted the lowest crude
polysaccharide content (0.63%). In addition, the outcomes obtained
from the crude polysaccharides derived from the hybrid strain Ac33
were found to betwice as much as the control utilized by Li etal.
Specically, the control group exhibited a dry weight of 7%, whereas
the selenium supplementation in the control group resulted in a 23%
dry weight (14).
Total polysaccharide content
Total polysaccharide content of cultivated, wild and hybrid strains
of A. cornea fruiting bodies was determined by the phenol-sulfuric
acid method and the results were shown in Figure 2. e total
polysaccharide content of fruiting bodies of the A. cornea mushroom
strain varied considerably, from 215.88 ± 2.4 mg. g−1 to 37.63 ± 4.3 mg.
g−1. e highest contents of total polysaccharides were obtained from
cultivated strained Ac1 (215.88 mg. g
−1
). e lowest total
polysaccharide content of fruiting bodies was observed in the
cultivated strain Ac6 (37.63 mg. g−1). e study conducted by Su etal.
revealed that the Auricularia species exhibited a range of 71.3 to
81.49 g in total polysaccharide content. e outcome of 100 g
−1
is
comparable to these results (22).
Mineral content
e mineral composition of the fruiting body of domesticated,
wild, and hybrid A. cornea strains are shown in Table 3. e copper
and manganese content of the A. cornea was 0.133 to 8.40 mg. kg−1 and
213 to 788 mg. kg−1, respectively. e cultivated strain Ac46 showed
the highest copper content (8.40 mg. kg
−1
), followed by wild strain
Ac49 (8.36 mg. kg
−1
) and hybrid strain Ac19 (8.2 mg. kg
−1
), while wild
strain Ac29 contained the lowest copper content (0.133 mg. kg−1).
Signicant dierences were observed in the manganese content of
A. cornea strains, with the highest manganese content in hybrid
strains Ac3 (788 mg. kg
−1
), followed by cultivated strain Ac40 (778 mg.
kg
−1
), and then wild strain Ac27 (774 mg. kg
−1
). In contrast, the hybrid
strain Ac20 showed the lowest (213 mg. kg
−1
). Among the 50 A. cornea
stains, the cultivated strain Ac46 showed the highest zinc content
(486.33 mg. kg
−1
). At the same time, the wild strain Ac28 demonstrated
the highest iron content (350 mg. kg
−1
). In contrast, the wild strain
Ac28 contained the lowest zinc content (169 mg. kg
−1
), while the
cultivated strain Ac36 showed the lowest iron content (27 mg. kg
−1
).
In general, A. cornea was high in zinc and iron contents. Mushrooms
are good natural zinc and iron accumulators and biologically essential
for the human body. Our ndings are consistent with the results of
Wang etal., who investigated the mineral content of various A. cornea
strains. In addition, prior study of Rebecca etal., showed lower results
FIGURE1
Crude polysaccharides percentage of fruiting bodies of A. cornea strains.

Khan et al. 10.3389/fnut.2023.1167805
Frontiers in Nutrition 07 frontiersin.org
for iron, manganese, copper, and iron contents compare to our
results (15).
In the current study, wefound that A. cornea mushrooms can
beused in various food items. Malnutrition is currently causing health
issues for people all over the world. It is estimated that 17% of the
population is at risk of zinc deciency (12). is decline is due to
insucient levels of these elements (copper, manganese, zinc, and
iron) in a healthy diet. Implementing eective strategies to prevent
and regulate these nutrients in the human diet is therefore essentially
required. Hence, there is a trend of increasing dietary supplements
worldwide. While the increase in their chemical composition requires
a natural process of absorption and accumulation, mushrooms are
screened for their high nutritional and commercial value (23). e
A. cornea mushrooms are considered to bea signicant source of vital
nutrients. us, the utilization of A. cornea mushrooms has the
potential to eciently mitigate nutritional insuciencies prevalent in
impoverished and malnourished populations. Furthermore, these
ndings establish the basis for novel germplasm advancements.
DPPH radical scavenging activity
DPPH radicals are static and are commonly used to assess the
radical scavenging activity of biological compounds. Biological
compounds can transfer an electron or a hydrogen atom to a DPPH
radical, which is how they scavenge DPPH radical (24). is is a
commonly used technique to determine the sensitivity, incompetence,
and velocity of many samples to determine their antioxidant capacity
(25). As shown in Figure3A, the DPPH radical scavenging capacity of
all crude polysaccharide A. cornea has a concentration-dependent
connection. e concentration-dependent DPPH radical scavenging
potential of strains of A. cornea is demonstrated in Figure3A. When
the concentration of crude polysaccharides increased from 0.25–
1.50 mg/mL, the scavenging activity of crude polysaccharides on
DPPH free radicals progressively increased. e highest scavenging
rate appears at a crude polysaccharide concentration of 1.50 mg/
mL. e strongest scavenging rates of Ac1, Ac3, Ac11, Ac13, Ac15,
Ac24, and Ac33 were 32.1, 23.6, 19.2, 35.6, 26.3, 40.8, and 46.2%,
respectively, weaker than Vc (vitamin C). Seven types of A.cornea
mushroom strains crude polysaccharides scavenge free radicals:
Ac33 > Ac24 > Ac13 > Ac1 > Ac15 > Ac3 > Ac11. e scavenging ac tivity
on DPPH radicles was similar to that of crude polysaccharides from
Lepista nuda, and was relatively smaller than that of polysaccharides
from Auricularia species (10, 22, 26).
ABTS radical scavenging activity
ABTS radical scavenging activity is a simple and commonly used
procedure for measuring the antioxidant activity of natural
FIGURE2
Total polysaccharide contents of fruiting bodies of A. cornea strains.

Khan et al. 10.3389/fnut.2023.1167805
Frontiers in Nutrition 08 frontiersin.org
TABLE3 Mineral contents of A. cornea strains.
Strains Copper (mg/
kg)
Manganese
(mg/kg)
Zinc (mg/kg) Iron (mg/kg) Strains Copper (mg/
kg)
Manganese
(mg/kg)
Zinc (mg/kg) Iron (mg/kg)
AC1 7.200±0.1bc 483.33±5fg 318.00±13mnopqrs 229.00±5.1hi AC26 0.700±0.1wxyz 276.00±18o417.7±33bcdefg 187±8.6mn
AC2 2.366±0.2opqr 375.33±8j391.67±35cdefghij 92.333±3.4qrs AC27 1.300±0.2tuvwx 774.00±11a243.7±27tuvw 343.7±8.0ab
AC3 4.266±0.3ijkl 788.33±19a215.00±12vwx 77.333±3.3rstu AC28 0.966±0.2vwxyz 340.00±12m169.3±14x350±27.5a
AC4 1.400±0.2tuvw 340.67±16m197.00±6wx 96.333±5.2pqr AC29 0.133±0.0z669.00±11b357.7±27ghijklmno 332±7.8abc
AC5 2.76±0.7mnopq 462.00±27gh 326.33±33klmnopq 200.00±2.2klm AC30 1.833±0.5rstu 670.00±13b376±45efghijklm 299.3±1.2e
AC6 1.833±0.2rstu 543.67±15de 232.33±39uvwx 177.00±8.2no AC31 6.733±0.2cd 457.67±7h433.3±23abcde 95±3.3qrs
AC7 3.033±0.2mnop 366.67±17jkl 285.67±44qrstu 245.67±30.9gh AC32 3.466±0.3lm 381.00±13j436±13abcde 159±30.7o
AC8 4.400±0.2ijk 207.00±4p174.33±45x220.33±8.2ijk AC33 2.90±0.6mnopq 766.00±11a354.7±34ghijklmno 304.3±3.4de
AC9 1.500±0.3stuvw 566.33±19cd 316.00±25mnopqrs 68.667±2.1tu AC34 7.700±0.4ab 458.00±4h254.67±17stuvw 81±5.7rst
AC10 6.300±0.2de 301.33±9n244.33±59tuvw 58.000±2.9uAC35 5.100±1.3ghi 226.00±4p361.0±43fghijklmno 65.03±4.2tu
AC11 0.500±0.2xyz 497.33±14f313.33±8mnopqrs 92.333±5.0qrs AC36 3.233±1.0mn 575.67±9c328.3±10jklmnopq 27±4.3v
AC12 4.933±0.4ghij 343.67±9lm423.67±6abcdef 67.667±2.5tu AC37 4.266±0.4ijkl 672.33±5b357±45ghijklmno 87±2.8qrst
AC13 4.366±0.4ijk 295.33±6n387.33±18defghijk 75.000±2.2rstu AC38 3.200±0.9mno 340.33±5m408.33±47bcdefgh 197±3.7lmn
AC14 7.200±0.3bc 428.00±23i440.00±11abcd 97.00±0.8pqr AC39 0.366±0.2yz 561.67±5cd 350±28hijklmnop 204±5.6jklm
AC15 2.433±0.2nopqr 380.00±7j291.00±21pqrstu 275.67±15.9fAC40 1.100±0.2uvwxy 778.33±13a310.3±58nopqrs 311±8.2cde
AC16 6.166±0.2def 536.00±20e280.67±50qrstu 187.67±8.2mn AC41 1.466±0.2stuvw 569.00±5c360.3±19fghijklmno 257.7±17.9fg
AC17 3.333±0.3m440.33±11hi 350.67±27hijklmnop 93.333±2.6qrs AC42 3.600±0.4klm 448.0±11hi 460±32ab 332.3±9.0abc
AC18 5.366±0.4fgh 667.67±10b383.33±39defghijkl 217.7±12.5ijkl AC43 0.700±0.4wxyz 771.33±7a454±32abc 216.3±4.2ijkl
AC19 8.200±0.4a338.67±13m285.33±7qrstu 72.667±5.6stu AC44 2.300±0.3pqrs 455.33±8h366±48fghijklmn 304.3±12.5de
AC20 4.233±0.8jkl 213.33±4p300.33±1opqrst 185.67±10.7mn AC45 6.500±0.3cde 770.00±4a369.3±34fghijklmn 108.7±6.1pq
AC21 4.866±0.2hij 543.67±19de 246.33±29tuvw 221.33±7.1ijk AC46 8.400±0.4a347.6±10klm 486.33±40a229.3±26.6hi
AC22 6.333±0.3de 658.67±12b400.33±1bcdefghi 325.0±12.6bcd AC47 1.700±0.4rstuv 453.67±2h402.33±58bcdefghi 318.3±5.2cde
AC23 1.16±0.1uvwxy 452.33±17hi 341.67±13ijklmnopq 318.67±3.3cde AC48 5.766±0.5efg 560.33±5cde 320.33±18lmnopqr 322±8.6bcd
AC24 1.266±0.2tuvwx 371.00±25jk 261.67±12rstuv 310.67±6.0cde AC49 8.366±0.5a676.00±1b354.7±15ghijklmno 18,833±5.2p
AC25 2.100±0.2qrst 560.3±15cde 373.0±57efghijklmn 224.67±12.4hij AC50 6.666±0.4cd 774.00±10a435.33±13abcde 229±18.2hi
Values with no letter in common in each column are signicantly dierent (p < 0.05) (means ± SD, n = 3).

Khan et al. 10.3389/fnut.2023.1167805
Frontiers in Nutrition 09 frontiersin.org
ingredients. As shown in Figure3B, crude polysaccharides from 7
A. cornea strains showed 11.9–76.3% ABTS radical scavenging
activity at concentrations of 0.25–1.50 mg/mL. It was found that
ABTS radical scavenging activity increased with increasing crude
polysaccharide concentration. e crude polysaccharides of
commercially cultivated strain Ac33 achieved 76.3% maximum ABTS
radical scavenging activity at 1.50 mg/mL, while the hybrid strain
Ac11 obtained 11.9% minimum ABTS radical scavenging activity at
0.25 mg/mL. However, at a maximum concentration of 1.50 mg/mL,
standard vitamin C (Vc) had 95.3% ABTS radical scavenging activity.
e potential of seven crude polysaccharides to scavenge ABTS free
radicals was Ac33 > Ac24 > Ac1 > Ac13 > Ac15 > Ac3 > Ac11. Similarly,
the polysaccharides obtained from Pleurotus sajor caju showed ABTS
radical scavenging capacity of 16.01 to 70.09% at dierent 25 to125
μg/mL concentrations. In comparison, polysaccharides from
Pleurotus sajor caju showed an ABTS scavenging capacity of 63.96%
at 5 mg/mL concentrations (27). Similarly, at a 10 mg/mL
concentration, the ABTS clearance eciency of melanin extracted
from black fungus was 95.6%29. Our results correlate signicantly
with previous work (28).
Principal components analysis
e dierences and similarities between the chemical
compounds and agronomic traits of A. cornea mushroom strains
were subjected to principal component analysis (PCA) as shown in
Figure4. e study involved the analysis of six distinct components,
namely the total number of days required for harvesting of fruiting
bodies and biological eciency, across a sample of 50 strains of
A. cornea. Principal Component Analysis (PCA) is a commonly
employed technique aimed at reducing a large number of variables
to a limited set of principal components. ese components are
selected based on their ability to account for the maximum variance
present in the data being analyzed. e distributions of all the
samples are conveniently positioned around the center of the map,
as shown by the results. e rst two principal components (PC1
and PC2) accounted for 46.86% of the total variance (26.14 and
20.72%, respectively). e PC1 was associated with the contents of
iron, zinc, manganese, total polysaccharides of fruiting bodies,
biological eciency whereas the PC2 was correlated with MFD and
Copper. e components were closed to each other, positively
correlated, such as iron, manganese, the total polysaccharides of
fruiting bodies.
On the other hand, certain compounds such as zinc, crude
polysaccharides and biological eciency were not signicantly
correlated with iron, manganese, the total polysaccharides of fruiting
bodies, but they were closely signicant with each other. Some
FIGURE3
Antioxidant activities of crude polysaccharides of A. cornea strains. (A) DPPH radical scavenging and (B) ABTS scavenging activities.
FIGURE4
Biplot based on Principal Component Analysis of mushroom
chemical composition and A. cornea strains arrangement. (Ac),
mushroom strains; (MFD), numbers of days for harvesting of fruiting
bodies; (BE), biological eciency; (Zn), zinc; (Fe), iron; (Cu), copper;
(Mn), manganese, and (TPB), total polysaccharides of fruiting bodies.

Khan et al. 10.3389/fnut.2023.1167805
Frontiers in Nutrition 10 frontiersin.org
compounds were separated, they were negatively correlated, such as
copper and days to maturity of fruiting bodies. e principal
component analysis (PCA) results elucidated the interrelationships
among dierent compounds and explicated their distinct and
armative correlations.
Conclusion
e study determined that the crude polysaccharides derived
from various strains of A. cornea mushrooms exhibit natural
antioxidant properties. Additionally, the investigation revealed that
wild, hybrid, and commercial strains of A. cornea mushrooms are
capable of attaining accelerated growth, premature maturation, and
elevated productivity. e scientic basis for commencing high-
quality breeding and producing “functional food” with genuine
nutritional and health value, as well as the development of innovative
antioxidant food additives and active ingredients of dierent fungal
strains, was provided by the assessment of biochemical indexes and
nutritional characteristics of strains with exceptional traits.
Additionally, the germplasm resources were established for this
purpose, along with abundant resources of crude polysaccharides.
Data availability statement
e original contributions presented in the study are included in
the article/supplementary material, further inquiries can bedirected
to the corresponding authors.
Author contributions
AK, F-JY, MF, L-XL, and Y-MZ: conceptualization. PW and J-JM:
methodology. AK and BX: writing and review. F-JY, MF, L-XL, and
Y-hW: supervision. K-SS, X-XM, and QH: analysis. All authors
contributed to the article and approved the submitted version.
Funding
e research was supported by China Agriculture Research
System (No. CARS-20) and e project of “one thousand talents plan”
in Jiangxi Province, China.
Conflict of interest
e authors declare that the research was conducted in the
absence of any commercial or nancial relationships that could
beconstrued as a potential conict of interest.
Publisher’s note
All claims expressed in this article are solely those of the authors
and do not necessarily represent those of their aliated organizations,
or those of the publisher, the editors and the reviewers. Any product
that may be evaluated in this article, or claim that may be made by its
manufacturer, is not guaranteed or endorsed by the publisher.
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