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Extraction and chromatographic separation of tannin fractions from tannin-rich plant material

November 2007
Polish Journal of Food and Nutrition Sciences 57(4):471-474

Authors:

Magdalena Karamać

Institute of Animal Reproduction and Food Research

Agnieszka Kosinska

HES-SO University of Applied Sciences and Arts Western Switzerland

Anna Rybarczyk

Warsaw University of Life Sciences

Ryszard Amarowicz

Polish Academy of Sciences

The crude phenolic extracts were obtained from red bean, adzuki bean, red lentil, green lentil, broad bean, faba bean, field bean, vetch, buckwheat, buckwheat groat, hazelnuts, walnuts, and almonds using 80% (v/v) acetone. The tannin fractions were separated from the crude extracts using Sephadex LH-20 column chromatography with ethanol and 50% (v/v) acetone. The tannin fractions were characterised by colour reaction with vanillin/HCl reagent and ability to bovine serum albumin (BSA) precipitation. The yield of extraction of phenolic compounds ranged from 3.77% (buckwheat) to 17.20% (walnuts). The content of tannin fraction in the crude extracts was differentiated and ranged from 10.5% (faba bean) to 45.5% (broad bean). The tannin fraction from buckwheat possessed the highest content of tannins determined using vanillin method (1.04 absorbance unit at 500 nm/mg) whereas the lowest content was noted for broad bean (0.066 absorbance unit at 500 nm/mg). In the model system, the highest amount of BSA was precipitated by tannin fraction of hazelnuts, whereas the lowest was noted for adzuki bean.

Content of tannins in tannin fractions determined using vanillin/HCl assay. The results are expressed as absorbance unit at 500 nm per mg of tannin fractions.

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BSA precipitation capacity of tannin fractions. The results are expressed as absorbance unit at 510 nm per mg of tannin fractions.

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POLISH JOURNAL OF FOOD AND NUTRITION SCIENCES

www.pan.olsztyn.pl/journal/

e-mail: joan@pan.olsztyn.pl

Pol. J. Food Nutr. Sci.

2007, Vol. 57, No. 4, pp. 471–474

EXTRACTION AND CHROMATOGRAPHIC SEPARATION OF TANNIN FRACTIONS FROM

TANNIN-RICH PLANT MATERIAL

Magdalena Karamać, Agnieszka Kosińska, Anna Rybarczyk, Ryszard Amarowicz

Division of Food Science, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn

Key words: tannins, leguminous seeds, nuts, buckwheat, extraction, Sephadex LH-20, column chromatography, protein precipitating capacity

The crude phenolic extracts were obtained from red bean, adzuki bean, red lentil, green lentil, broad bean, faba bean, field bean, vetch, buck-

wheat, buckwheat groat, hazelnuts, walnuts, and almonds using 80% (v/v) acetone. The tannin fractions were separated from the crude extracts

using Sephadex LH-20 column chromatography with ethanol and 50% (v/v) acetone. The tannin fractions were characterised by colour reaction with

vanillin/HCl reagent and ability to bovine serum albumin (BSA) precipitation. The yield of extraction of phenolic compounds ranged from 3.77%

(buckwheat) to 17.20% (walnuts). The content of tannin fraction in the crude extracts was differentiated and ranged from 10.5% (faba bean) to 45.5%

(broad bean). The tannin fraction from buckwheat possessed the highest content of tannins determined using vanillin method (1.04 absorbance unit

at 500 nm/mg) whereas the lowest content was noted for broad bean (0.066 absorbance unit at 500 nm/mg). In the model system, the highest amount

of BSA was precipitated by tannin fraction of hazelnuts, whereas the lowest was noted for adzuki bean.

INTRODUCTION

According to a definition of Bate-Smith, tannins are

“water-soluble phenolic compounds having molecular weight

between 500 and 3 000, and besides giving the usual phenolic

reactions, they have special properties such as the ability to

precipitate alkaloids, gelatin and other proteins” [Bate-Smith

& Swein, 1962]. Tannins are divided into three main classes.

The condensed tannins (proanthocyanidins) are flavan-3-ol

based biopolymers that at high temperature in alcohol solu-

tions of strong mineral acid release anthocyanidins and cat-

echins as end groups. Gallotannins and ellagitannins belong

to hydrolysable tannins. Gallotaninns are comprised of gal-

loyl esters of glucose or quinic acid whereas ellagitannins are

derivatives of hexahydroxydiphenic acid [Hagerman et al.,

2005]. Phytochemists and nutritionists are used to call tan-

nins “a double-edged sword in biology and health” [Chung et

al., 1998]. Tannins act as an antinutrient compound of plant

origin because they precipitate proteins, inhibit digestive

enzyme, decrease the utilization of vitamins and minerals.

Yet, tannins have also been considered a health-promoting

component in plant-derived foods and beverages. For exam-

ple, tannins have been shown to have anticarcinogenic and

antimutagenic potential, and antimicrobial properties [Cos et

al., 2004; Awika et al., 2006]. Several studies have reported on

antioxidant and antiradical activity of tannins [Amarowicz et

al., 2004; Alasalvar et al., 2006; Amarowicz, 2007].

The aim of the study was to determine yield of tannins

extraction from tannin-rich plant material (1), to compare the

content of tannins fractions separated from the crude extracts

using Sephadex LH-20 column chromatography (2), and to

characterize tannin fractions by vanillin reaction and their

protein precipitating activity (3).

MATERIALS AND METHODS

Materials. Seeds of red bean, adzuki bean, red lentil,

green lentil, broad bean, faba bean, field bean, vetch, and

buckwheat were obtained from the Plant Breading Station in

Olsztyn. Roasted buckwheat groat, hazelnuts, walnuts, and

almonds were acquired at a local market in Olsztyn.

Chemicals. Sephadex LH-20, vanillin, bovine serum albu-

min (BSA), sodium dodecyl sulphate (SDS), were obtained

from Sigma-Aldrich Co. Ltd. (Poznań, Poland). Acetone,

ethanol, and triethanolamine, all analytical grade, were pur-

chased from P.O.Ch. Company (Gliwice, Poland).

Extraction of phenolic compounds. Ground plant

material (20 g) was weighed out into sealable flasks and

160 mL of 80% acetone (v/v) was poured into [Amarowicz

et al., 1995]. Flasks were placed in a water bath at 70°C and

shaken for 15 min. After cooling, supernatant was decant-

ed carefully. Extraction was repeated twice more. Superna-

tants were combined, acetone was evaporated using rota-

ry evaporator at 40°C, and aqueous residue was lyophilised.

Hazelnuts, walnuts, and almonds were defatted using hexane

before extraction.

Author’s address for correspondence: Magdalena Karamać, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, ul.

Tuwima 10, 10-747 Olsztyn, Poland: tel.: (48 89) 523 46 27; fax: (48 89) 524 01 24; e-mail: magda@pan.olsztyn.pl

472 M. Karamać et al.

Isolation of tannins. The crude phenolic extract (2 g)

dissolved in 20 mL of ethanol was applied on a column

(5 × 40 cm) packed with Sephadex LH-20 gel. Ethanol (1L),

used as first eluent, allowed removing low molecular weight

phenolic compounds. Then 600 mL of 50% acetone (v/v)

was used to elute tannins. Solvent from tannin fractions was

removed using rotary evaporator, and water was removed

during lyophilisation.

Content of condensed tannins. The content of con-

densed tannins in such obtained materials was determined

according to a modified vanillin assay [Price et al., 1978].

Tannin fractions were dissolved in methanol (0.5 mg/mL).

To 1 mL of prepared solution, 5 mL of vanillin/HCl reagent

(0.5 g vanillin in 4% hydrochloric acid in methanol (v/v)) was

added. Samples and controls (without vanillin) were allowed

to stand for 20 min in darkness and then absorbance at

500 nm was read. Results were expressed as absorbance units

per 1 mg of tannin fraction.

BSA precipitation method. To 1 mL of tannin solution

in water (1 mg/mL), 2 mL of bovine serum albumin solu-

tion in 0.2 mol/L acetic buffer, pH 5.0 with 0.17 mol/L NaCl

(1 mg/mL) was added and mixed carefully [Hagerman &

Butler, 1978]. After 15 min the samples were centrifuged at

5000 g for 15 min. The supernatant was removed, and pel-

let was dissolved in 4 mL of aqueous solution containing

1% SDS and 4% triethanolamine. Then 1 mL of 0.01 mol/L

FeCl3 in 0.01 mol/L HCl was added. After 30 min the absor-

bance was recorded at 510 nm. Results were expressed as

absorbance units per 1 mg of tannin fraction.

RESULTS AND DISCUSSION

The range of solvent used for extraction of various groups

of phenolic compounds from plant material is very broad

and includes water, methanol, ethanol, water-ethanol, water-

-methanol, acetone-water, dimethyl-formamid-water [Ama-

rowicz et al., 1995; Naczk et al., 2005, 2007]. According to

Amarowicz et al. [1995], 80% acetone (v/v) ensured the most

complete extraction of phenolic compounds from lentil seeds,

especially of flavonols and tannins. The high capability of

acetone-water system to extract phenolic compounds and

high antioxidant activity of the extracts obtained this way was

confirmed by Troszyńska et al. [1993], Naczk et al. [2005],

Rocha-Guzmán et al. [2007], and Pegg et al. [2007].

The yield of extraction is presented on Figure 1. The

result ranged from 3.77% (buckwheat) to 17.2% (walnuts)

and they were in order of walnuts > almonds ~ hazelnuts >

red bean > red lentil ~ green lentil ~ vetch ~ field bean >

broad bean ~ faba bean > adzuki bean > buckwheat groat

~ buckwheat. These results are in accordance with litera-

ture data. The yield of extraction from whole grains (wheat,

barley, rye, oat, buckwheat) using 80% methanol (shaking at

20°C for 40 min) ranged from 3.82% (oat) to 7.44% (rye cv.

Dańkowskie Złote) [Zieliński & Kozłowska, 2000]. The con-

tent of the 70% acetone extract in common bean cultivars

reported by Rocha-Guzmán et al. [2007] was 6.13% – 6.83%

(extraction for 24 h at room temperature). Different variet-

ies of cow pea (Vigna unguicula (L.) Walp.) seeds were char-

acterized by the content of the extracts from 4.00% to 9.73%

[Siddhuraju & Becker, 2007] (extraction using 70% acetone

at 25°C for 24 h). A yield of extraction (10% - 15%) from

sage using ethanol-water mixture was reported by Durling et

al. [2007].

The content of tannin fractions in the crude extracts was

differentiated and ranged from 10.5% (faba bean) to 45.5%

(broad bean) (Figure 2). The results were in order of broad

bean > vetch > walnuts ~ adzuki bean ~ buckwheat > red

bean ~ field bean ~ buckwheat groat > almonds ~ red len-

til ~ green lentil ~ hazelnuts > faba bean. For Sephadex LH-

-20 column chromatography the first solvent used was ethanol.

Ethanol can elute low-molecular weight phenolics together

with sugars. Condensed tannins are available to be eluted with

the system acetone-water (1:1; v/v). Therefore the high content

of phenolic compounds in the extract can be caused also by the

content of sugars in the crude extract. It seems to be interesting

to compare in the future the content of sugars and tannin frac-

tions in the crude extracts in tannin-rich plant material.

The vanillin/HCl reaction is the principal colorimetric

method used for determination condensed tannins and fla-

van-3-ols (catechins) in plant material. In our study only con-

6.12 4.55 5.39 5.29 4.94 4.83 5.15 5.22 3.77 3.94 8.48 17.2 8.88

Red bean

Adzuki bean

Red lentil

Green lentil

Broad bean

Faba bean

Field bean

Vetch

Buckwheat

Buckwheat groat

Hazelnuts

Walnuts

Almonds

Extraction yield (%)

FIGURE 1. Extraction yield of crude phenolics (%) from tannin-rich

plant material.

13.3

21.1

12.114.5

19.130.1

15.5

10.545.512.5

13.2

20.5

16.6

Red bean

Adzuki bean

Red lentil

Green lentil

Broad bean

Faba bean

Field bean

Vetch

Buckwheat

Buckwheat groat

Hazelnuts

Walnuts

Almonds

Tannin fraction content (%)

FIGURE 2. Content (%) of tannin fractions in the crude phenolic

extracts.

473

Extraction and chromatography of tannins

densed tannins gave the colour reaction with vanillin reagent

because catechins were eluted with methanol from the col-

umn as the low-molecular phenolic fraction. The content of

tannins in this work was expressed as absorbance units per

1 mg of tannin fraction (A500/mg). The tannin fraction from

buckwheat (1.04) possessed the highest content of tannins

determined using vanillin method whereas the lowest content

was noted for broad bean (0.066) (Figure 3). The results were

in order of buckwheat ~ buckwheat groat > hazelnuts >

almonds > red bean > green lentil ~ vetch ~ adzuki bean >

red lentil > faba bean > walnuts ~ field pea ~ broad bean.

The presence of tannins in leguminous seeds has been report-

ed by several authors [Ariga et al., 1988; Ariga & Hamano,

1990; Chavan et al., 1999; De Pascual et al., 2000; Amarow-

icz et al., 2000; Dueñas et al., 2002, 2003, 2004]. The content

of tannins in tannin fractions separated in this study from

buckwheat, buckwheat groat, hazelnuts, almonds, and red

bean was higher than that reported by Naczk et al. [2001] for

the extracts of canola and rapeseed hulls (0.007–0.286 absor-

bance units at 500 nm /mg). The content of tannins in tan-

nin fractions from beach pea and evening primrose was 0.684

and 1.328, absorbance unit at 500 nm/mg, respectively [Ama-

rowicz et al., 2000].

Figure 4 characterises the ability of tannin fraction to pre-

cipitate bovine serum albumin (BSA), results are reported

as absorbance units at 510 nm/mg. In the model system the

highest amount of BSA was precipitated by tannin fraction

of hazelnuts (0.560), the lowest result was noted for adzu-

ki bean (0.006). The results were in order of hazelnuts >

walnuts > buckwheat groat > buckwheat > almonds > red

bean ~ red lentil > faba bean ~ vetch ~ field bean ~ broad

bean > green lentil > adzuki bean. Naczk et al. [1996] using

the same method reported the protein precipitating capac-

ity of crude canola tannins app. 0.03 absorbance units at

510 nm/ mg. Tannin fractions separated from wild blueber-

ry leaves and fruits exhibited BSA precipitating activity of

0.651 and 0.742 absorbance units at 510 nm/mg [Naczk et

al., 2006].

In this study the high content of condensed tannins deter-

mined using vanillin method in the case of buckwheat, buck-

wheat groats, and hazel-nuts was correlated well with the pro-

tein precipitating capacity (Figures 3 and 4). Very week BSA

precipitating activity of the tannin fractions separated from the

almonds and leguminous seeds was caused by the low degree

of polymerisation of tannins. Walnuts tannins showed a week

colour reaction with vanillin reagent but strong BSA precip-

itating activity (Figures 3 and 4). This phenomenon can be

explained by the presence of hydrolysable tannins in walnuts.

This class of tannins does not react with vanillin but is able to

make complexes with BSA. This explanation is in accordance

with results of Amarowicz et al. [2007] who found in walnuts

the presence of gallotannins and ellagotannins.

CONCLUSIONS

The extraction with 80% acetone (v/v) together with a

Sephadex LH-20 column chromatography with ethanol and

50% acetone as mobile phases are a useful method for tan-

nins separation from tannin-rich plant material. The method

is characterized by a high repeatability. Among investigated

plants the richest source of tannins were buckwheat and nuts.

Most probably hydrolysable tannins are responsible for pro-

tein precipitating activity of the walnut extract.

ACKNOWLEDGEMENTS

We acknowledge financial support of the Polish Minis-

try of Science and Higher Education for 2005-2007; research

project 2P06T 08529.

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EKSTRAKCJA I CHROMATOGRAFICZNE WYODRĘBNIANIE FRAKCJI TANINOWYCH Z BOGATEGO

W TANINY MATERIAŁU ROŚLINNEGO

Magdalena Karamać, Agnieszka Kosińska, Anna Rybarczyk, Ryszard Amarowicz

Instytut Rozrodu Zwierząt i Badań Żywności Polskiej Akademii Nauk, Oddział Nauki o Żywności, Olsztyn, Polska

Surowe ekstrakty związków fenolowych uzyskano z czerwonej fasoli, fasoli adzuki, zielonej i czerwonej soczewicy, bobu, bobiku, peluszki,

wyki, gryki, kaszy gryczanej, orzechów laskowych, orzechów włoskich i migdałów stosując 80% (v/v) aceton. Frakcje taninowe wyodrębnio-

ne z ekstraktów na drodze chromatografii kolumnowej na żelu Sephadex LH-20 z etanolem i 50% (v/v) acetonem scharakteryzowano reak-

cją barwną z odczynnikiem wanilinowym oraz poprzez zdolność do precypitacji albuminy surowicy bydlęcej (BSA). Ekstrakcyjność wahała

się od 3,77% (gryka) do 17,20% (orzech włoski). Zawartość frakcji taninowej w surowym ekstrakcie wahała się od 10,50% (bobik) do 45,50%

(bób). Posługując się metodą wanilinową największą zawartość tanin stwierdzono we frakcji acetonowej z gryki (1.04 jednostki absorbancji

przy 500 nm/mg), najniższą w przypadku bobu (0.066 jednostki absorbancji przy 500 nm/mg). W badaniach modelowych najwyższą zdol-

nością do precypitacji BSA charakteryzowała się frakcja taninowa z orzechów laskowych, najniższą zdolność zanotowano w przypadku frak-

cji taninowej z fasoli adzuki.

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Nov 2022

Nowadays to move toward a more sustainable agriculture, use of pesticide alternatives that have positive effects and play critical roles toward reducing the use of pesticides should be used. Laboratory bioassays were carried out to analyze the bioactivity of tannins isolated from urtica weed leaves (U), bean hull (B), black tea (BT) and green tea (GT) against larvae of cotton leafworm Spodoptera littoralis (Boisduval) using food mixing technique and essential oil isolated from onion against larvae of cotton leafworm, adults of rice weevil and houseflies using fumigation technique. The results showed that during the first week of treatment, tannins extracted from U had the strongest antifeedant activity with an EC50 of 33.034 μg/g followed by tannins extracted from B (EC50 = 47.839 μg/g). In the second and third week, tannins isolated from B depicted highest antifeedant activity (EC50 = 37.733 and 84.828, respectively). Furthermore, the isolated tannins induced notable larval growth inhibition on S littoralis. On the other hand, mortality percentage of onion essential oil on tested insects clearly increased with both increased concentration and exposure time. The LC50 (μg/cm3) at 30 min reflected that the essential oil had a greater toxicity to cotton leafworm with a LC50 = 2.15 μg/cm3 while least toxic to house flies (LC50 = 16.09). The repellency action based on LT50 values was seen to be highly effective in houseflies (LT50 = 1.85 min). The results demonstrated that tannins and essential oil could be applicable in the management of insect pests to decrease ecologically detrimental effects of synthetic insecticides.

Effect of Oven Drying Temperature on The Tanin Content of Bungur (Lagerstroemia speciosa Auct. non (L.) Pers) Leaves

Article

Full-text available

Nov 2024

A study was conducted on the effect of oven drying temperature on tannin content of bungur leaves (Lagerstroemia speciosa Auct. non (L.) Pers). Bungur leaves were picked, dry sorted, washed, wet sorted, and drained then oven dried at 30oC, 60(o)C, 90oC respectively. After drying, the samples were then measured for moisture content and then made into bungur leaf powder. Bungur leaf powder was then extracted by modified maceration using aquadem solvent. The extract obtained was tested qualitatively and quantitatively. Qualitative test results showed the presence of tannins. Quantitative tests using permanganometry, obtained tannin levels at drying temperatures of 30oC, 60oC, and 90oC were 7.27% ± 0.1429, 15.26% ± 1.0610, and 9.92% ± 0.7156, respectively. The highest tannin content was obtained at 60oC drying temperature.

Exploring the Nutritional, Antioxidant, and Lipid-Lowering Properties of Saba Banana (Musa acuminata x balbisiana BBB Group) Peels

Article

Full-text available

Dec 2023
PHILIPP AGRIC SCI

This study investigated the nutritional and functional components of 'saba' banana peel (SBP) to determine its health-promoting potential for special food applications. SBP has undergone analyses measuring proximate composition, vitamin C, antioxidant activity, phytochemical content, estimated glycemic index (eGI), pancreatic lipase inhibition, and cholesterol micellar solubility inhibition. Data were processed using SPSS v20 and expressed as mean ± SD. Proximate analysis showed that SBP contained 83.83 ± 1.06% moisture, 6.74 ± 0.83% crude fat, 5.58 ± 0.24% crude protein, 9.97 ± 0.04% total ash, 9.91 ± 0.10% crude fiber, and 60.08% nitrogen-free extracts. Vitamin C content was found to be 72.15 ± 2.20 mg vitamin C/100 g fresh sample, whereas its antioxidant activity was 53.75 ± 1.29% DPPH inhibition. The eGI of SBP was 77.88 ± 1.42 and the phytochemical content analyses revealed that SBP contained total phenols at 135.61 ± 2.72 mg GAE, total flavonoids at 18.33 ± 0.65 mg catechin equivalent, and total tannins at 65.64 ± 1.97 mg quercetin equivalent. Finally, its pancreatic lipase inhibition was 35.34 ± 4.34%-almost 50% as effective as lipase inhibitor drug Orlistat. Its cholesterol micellar solubility inhibition was 71.40 ± 2.06%-almost 80% as effective as the cholesterol-lowering drug Cholestyramine. SBP had the highest phenolic content when compared with the published values of other fruit peels and far greater lipid-lowering enzyme inhibition effects than the healthy pigmented red and black rice varieties. These findings showed that SBP, which was considered as agricultural waste, contains nutritional properties and bioactive compounds, and can be utilized as food products and nutraceuticals with potentials in ameliorating obesity and associated disorders, providing banana farmers and processors additional revenue for their crops.

Variability in Productive and Biochemical Traits of Vicia faba L. Landraces from Apulia Region (South Italy)

Article

Full-text available

May 2023

The faba bean (Vicia faba L. var. major) is a pulse that is garnering attention for its chemical composition, which makes it suitable for a healthy diet. The Apulian germplasm is rich in local accessions at risk of genetic erosion, which need evaluating and promoting. Thirteen Vicia faba local Landraces have been analyzed in relation to their productivity and their chemical and biochemical characteristics: their protein, total phenol, total flavonoid, condensate tannin and L-DOPA levels. The results showed great variability—above all in the thousand-seeds weight and in their content of proteins and L-DOPA. Among the accessions evaluated, the two collected from the most southern area of the region (FV12-FV10) were particularly promising—both for their good biochemical traits and, especially, for the higher L-DOPA content (0.46 and 0.49 g 100 g−1 d.m., respectively), even when expressed in terms of yield per plant (116.3 and 153.0 mg plant−1 d.m., respectively).

LC-ESI-QTOF-MS Characterization of Phenolic Compounds in Different Lentil (Lens culinaris M.) Samples and Their Antioxidant Capacity

Article

Full-text available

Mar 2023

Background Lentil (Lens culinaris M.) is a legume widely consumed worldwide. It is rich in bioactive compounds, including polyphenolic compounds that contribute to positive health benefits. Methods This study aimed to determine the phenolic content and antioxidant activity of black, red, green, and brown whole lentils. Towards this end, the lentils’ phenolic compounds were evaluated regarding their total phenolic content (TPC), total flavonoid content (TFC), total tannin content (TTC), total condensed tannin (TCT), total proanthocyanin content (TPAC), total anthocyanin content (TAC). For the antioxidant activity 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), hydroxyl radical scavenging activity (•OH-RSA), ferrous ion chelating activity (FICA), reducing power assay (RPA) and phosphomolybdate (PMA) assay were accessed. To identify individual phenolic compounds, liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS²) was used. Results The results showed that green lentils exhibited the highest TPC (0.96 mg gallic acid equivalents (GAE)/g) whereas red lentils presented the highest TFC (0.06 mg quercetin equivalents (QE)/g). Black lentils were noted with the highest TCT (0.03 mg catechin equivalents (CE)/g), TPAC (0.009 mg cyanidin chloride equivalents (CCE)/g), and TAC (3.32 mg/100 g) contents. While the greatest TTC (2.05 mg tannic acid equivalents (TAE)/g) was observed in the brown lentil. Regarding the total antioxidant capacity, red lentils (4.01 mg ascorbic acid equivalents (AAE)/g) presented the greatest activity, whereas the lowest was found in the brown samples (2.31 mg AAE/g). The LC-ESI-QTOF-MS² tentatively identified a total of 22 phenolic compounds, containing 6 phenolic acids, 13 flavonoids, 2 lignans, and 1 other polyphenol. The relationships among phenolic compounds by Venn Diagram showed a high number of overlapping compounds in brown and red lentils (6.7%), and a low number of overlapping compounds between the green, brown, and black lentils (2.6%). Flavonoids were the most abundant phenolic compound within the studied whole lentils, with the brown lentils being the richest in phenolic compounds, especially flavonoids. Conclusions This study emphasized a comprehensive understanding of the antioxidant potential of lentils and disclosed the phenolic distribution across various lentil samples. This may increase interest in the development of functional food products, nutraceutical ingredients, and pharmaceutical applications with lentils.

Innovative Application of Phytochemicals from Fermented Legumes and Spices/Herbs Added in Extruded Snacks

Article

Full-text available

Dec 2021

A trend related to adding legume seeds to various products has been observed. This work aimed to use fermented red bean/broad bean seeds and their hulls to produce extruded snacks with more beneficial nutritional properties and good sensory quality. Extruded snacks containing fermented ground seeds (50%) or hull (10%) of red bean/broad bean and corn grits with the addition of selected herbs/spices (0.5%) were prepared. The chemical composition, phenolic profile, antioxidant activity, and sensory quality were analysed. The results showed that the protein content ranged from 9 to 22.9 g 100 g−1, phenolic compounds ranged from 3.97 to 12.80 mg 100 g−1 (with the addition of herbs/spices, even up to 62.88 mg 100 g−1), and antioxidant activities ranged from 4.32 to 10.23 Trolox g−1 (ABTS assay), depending on the type of fermented materials. The addition of ground seeds/hull did not influence the consumer desirability, whereas the addition of selected herbs/spices, particularly lovage, increased it. The application of fermented red bean and broad bean seeds and their hulls, as part of the assumptions of the planetary diet, enabled enrichment of extruded corn products, which are often consumed by vegans and vegetarians, with nutritionally valuable ingredients.

Diffusion of adzuki bean ( Vigna angularis ) oligomeric polyphenols from seed coats to cotyledons during boiling

Article

Oct 2024
BIOSCI BIOTECH BIOCH

Adzuki beans (Vigna angularis) are major legumes in East Asia, commonly used in traditional Japanese confections in the form of a paste. Although various types of polyphenols are present in seed coats, there are no reports on the diffusion of polyphenols to cotyledons during boiling. This study revealed that oligomeric polyphenols—such as dimeric and more proanthocyanidins—diffused more easily from seed coats to cotyledons than monomeric polyphenols—such as (+)-catechin and (-)-epicatechin—during heating. Microscopy suggested that diffusing polyphenols were bound to cotyledon proteins. Furthermore, bound polyphenols, poorly extracted by ethanol and acetone, contributed to the 1,1- diphenyl-2-picrylhydrazyl radical-scavenging activity of cooked cotyledons. Thus, smooth adzuki bean paste, made by boiling adzuki beans and removing the seed coats, contains oligomeric polyphenols that contribute to its antioxidant activity. By clarifying further physiological activities of polyphenols diffused through cotyledons, adzuki bean paste can be a potential functional ingredient.

Condensed tannins—Their content in plant foods, changes during processing, antioxidant and biological activities

Chapter

Apr 2024
Adv Food Nutr Res

Synthesis of a Tannin-Immobilized Magnetite/Graphene Oxide Composite for Magnetically Separable and Reusable Arsenic Adsorption

Article

Jul 2023

This study proposed a novel method to remove arsenic pollutants using a magnetically separable adsorbent based on a non-toxic biopolymer. We synthesized a tannin-immobilized magnetite/graphene oxide composite (BT–Fe 3 O 4 /GO) using tannin extracted from black tea leaves (BT) and a hydrothermal method. Various characterization methods, such as Field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS), confirmed the successful synthesis of BT–Fe 3 O 4 /GO. The interactions involved in the synthesis were subsequently demonstrated. The maximum adsorption capacity (12.25 mg/g) of BT–Fe 3 O 4 /GO was approximately three times higher than that of Fe 3 O 4 /GO (3.487 mg/g), which indicated that tannin and Fe 3 O 4 have synergetic adsorption affinities for As (V) ions. The adsorption performance of BT–Fe 3 O 4 /GO under acidic conditions was better than that under basic conditions. Based on the experimental results, the possible adsorption mechanisms of BT and Fe 3 O 4 were described. The adsorption capacity of BT–Fe 3 O 4 /GO was approximately 80% of that of fresh BT–Fe 3 O 4 /GO, even after the third adsorption cycle. Moreover, it retained sufficient magnetic properties to collect the adsorbent after As adsorption. Owing to the synergetic adsorption performance of tannin and Fe 3 O 4 , tannin immobilization is a promising removal method for As ions, and BT–Fe 3 O 4 /GO is expected to be an alternative adsorbent for As remediation.

Analisis Senyawa Tannin Dan Aktifitas Antibakteri Fraksi Buah Sirih (Piper betle L) Terhadap Streptococcus mutans

Article

Full-text available

Jun 2020

Kerusakan gigi salah satunya adalah karies gigi yang di sebabkan oleh bakteri Streptococcus mutans. Buah sirih (Piper betle L) dapat di gunakan untuk tanaman obat karena memiliki kandungan senyawa tanin sebagai antibakteri. Tujuan penelitian untuk mengetahui kandungan senyawa tanin dan uji aktifitas antibakteri fraksi n-heksan, kloroform dan etil asetat terhadap bakteri Streptococcus mutans. Jenis penelitian ini ialah Deskriptif Analitik. Pengujian kandungan senyawa tanin secara kualitatif ekstrak buah sirih menggunakan kromatografi lapis tipis (KLT) dan spektrofotometer Uv-Vis serta pengujian antibakteri pada konsentrasi 3%, 4%, 5% dan 6% untuk masing-masing fraksi. Hasil penelitian menunjukan bahwa ketiga fraksi: n-heksan, kloroform dan etil asetat positif mengandung senyawa tanin. Pengujian antibakteri pada konsentrasi 3%, 4%, 5% dan 6% menunjukan adanya aktifitas antibakteri dari ketiga fraksi : n-heksan ,kloroform dan etil asetat terhadap bakteri Streptococcus mutans dengan daya hambat berturut-turut untuk fraksi n-heksan 12.883±0.510; 12.600±1.455; 13.916±2.877; 13.550±3.347, untuk fraksi kloroform 16.400±1.646; 16.450±1.053; 17.183±1.830; 17.916±1.338 dan fraksi etil asetat 16.400±1.200; 16.000±0.327; 16.850±1.253; 17.450±1.297. Sehingga dapat disimpulkan ekstrak buah sirih mengandung senyawa tanin dan ketiga fraksi n-heksan ,kloroform dan etil asetat memiliki aktifitas antibakteri terhadap Streptococcus mutans dengan kategori kuat.Tooth decay one of which is dental caries caused by Streptococcus mutans bacteria. Betel fruit (Piper betle L) can be used for medicinal plants because it contains tannin compounds as antibacterial. The purpose of this study was to determine the content of tannin compounds and test the antibacterial activity of the n-hexane, chloroform and ethyl acetate fractions against Streptococcus mutans. This type of research is Descriptive Analytic. Testing the content of tannin compounds qualitatively betel fruit extract using thin layer chromatography (TLC) and Uv-Vis spectrophotometer and antibacterial testing at concentrations of 3%, 4%, 5% and 6% for each fraction. The results showed that all three fractions: n-hexane, chloroform and ethyl acetate positively contained tannin compounds. Antibacterial testing at concentrations of 3%, 4%, 5% and 6% showed antibacterial activity of the three fractions: n-hexane, chloroform and ethyl acetate against Streptococcus mutans with inhibitions for the n-hexane fraction 12.883 ± 0.510; 12,600 ± 1,455; 13,916 ± 2,877; 13,550 ± 3,347, for the chloroform fraction 16,400 ± 1,646; 16,450 ± 1,053; 17,183 ± 1,830; 17,916 ± 1,338 and the ethyl acetate fraction 16,400 ± 1,200; 16,000 ± 0.327; 16,850 ± 1,253; 17,450 ± 1,297. So it can be concluded that betel fruit extract contains tannin compounds and the three fractions of n-hexane, chloroform and ethyl acetate have antibacterial activity against Streptococcus mutans with a strong category.

Radical Scavenging Action and Its Mode in Procyanidins B-1 and B-3 from Azuki Beans to Peroxyl Radicals

Article

Oct 1990

Procyanidins B-1 and B-3 from azuki beans showed remarkable scavenging activities, especially to hydrophilic radicals. The inhibition rate constants for the scavenging of hydrophilic peroxyl radicals generated from 2,2′-azobis(2-amidinopropane)hydrochloride in aqueous media were calculated at 37°C to be kinh = 6.0 × 104 m−1s−1, 5.9 × 104 m−1 s−1, 2.7 × 104 m −1 s−1, 5.0 × 104 m−1 s−1 and 1.1 × 105 m−1 s−1, and the stoichiometric factors as n = 8.4, 8.0, 3.7, 1.2 and 1.7 for procyanidin B-1, procyanidin B-3, (+)-catechin, ascorbic acid and α-tocopherol, respectively. Thus, the dimeric procyanidin molecule could trap eight radicals. The production and structures of procyanidin B-3 radicals are discussed on the basis of the ESR spectra observed by autoxidation of procyanidin B-3 in an aqueous alkaline methanol solution.

Antioxidant Capacity of Phenolic Extracts from Selected Food By-Products

Chapter

Mar 2007

Potential use of blueberry leaves and canola hulls as a source of natural antioxidants was explored. Cyclone canola hulls and blueberry leaves were extracted with acetone (70%, v/v). Crude phenolic extracts were fractionated on Sephadex LH-20 column into two fractions; fraction A was rich in nontannin phenolics while fraction B was rich in condensed tannins. The total content of phenolics in the extracts ranged from 44 to 517 mg catechin equivalents per gram of extract. Higher levels of condensed tannins were detected in blueberry leaves extracts than in canola hull extracts. The fraction B exhibited stronger free radical scavenging activity than both fraction A and crude phenolic extract.

Antioxidant Capacity of Phenolics from Canola Hulls As Affected by Different Solvents

Article

Jul 2005

Potential use of canola hulls as a source of natural antioxidants was explored. The antioxidant activity of 80-100% (v/v) methanol and 70-80% (v/v) acetone extracts of canola hulls in a β-carotene-linoleate model system was comparable to that displayed by butylated hydroxyanisole (BHA). The scavenging effect of the above extracts, at 40 µ/assay on (DPPH) radical, was over 95%.

Extraction of phenolic compounds from lentil seeds (Lens culinaris) with various solvents

Article

Jan 1995

PHOTOCHEM for determination of antioxidant capacity of plant extract

Chapter

Mar 2007

The antioxidative capacities of water- (ACW) and lipid-soluble (ACL) compounds in selected plant extracts were investigated by a facile chemiluminescence assay using a PHOTOCHEM® device. Prepared extracts contained various classes of polyphenolics and included Cyclone canola hulls (i.e., phenolic acids and condensed tannins), arugula greens (i.e., quercetin and other flavonoids), bearberry-leaf (i.e., arbutin, condensed and hydrolyzable tannins), as well as the leaf material (i.e., a mixture of phenolics including condensed tannins) of east-coast Canadian wild blueberries. All extracts examined had demonstrated a capability to retard lipid oxidation in other model system studies, albeit to varying degrees. Using the PHOTOCHEM® device, the ethanolic extract from blueberry leaves exhibited the strongest antioxidative capacity at inhibiting the photo-induced chemiluminescence (PCL) of luminol; that is, 5.93 mmol ascorbic acid eq/g extract and 10.4 mmol Trolox eq/g extract for the ACW and ACL assays, respectively, while extracts from arugula greens were weakest with ACW data ranging from 0.06 to 0.16 mmol ascorbic acid eq/g extract. The crude bearberry-leaf extract also showed strong antioxidant activity; moreover, individual results for the ACW and ACL experiments correlated strongly to one another (r=0.955). The crude bearberry-leaf extract was fractionated on a Sephadex LH-20 column using 95% (v/v) ethanol and 50% (v/v) acetone as mobile phases. The ethanol fraction demonstrated a reduced antioxidative capacity at retarding PCL of luminol whereas the acetone fraction, which contained more tannin constituents, exhibited an enhanced capacity (ACW: 0.94 and 7.70 mmol ascorbic acid eq/g extract, respectively; ACL: 5.80 and 36.3 mmol Trolox eq/g extract, respectively). The simplicity and effectiveness of the PHOTOCHEM® device as a tool for measuring antioxidative capacity is discussed.

Antioxidative properties of procyanidin B1 and B3 from azuki beans in aqueous system

Article

Nov 1988

Two kinds of dimeric procyanidins were isolated in pure form from azuki beans by preparative HPLC. They were identified as procyanidins B-1 and B-3, on the basis of their UV, IR FAB-MS and 1H-NMR spectra, and an analysis of the acid hydrolyzed products. The procyanidins were evaluated as antioxidants for linoleic acid in an aqueous linoleic acid-β-carotene model system. In the range of the tested concentrations (5 × 10-5 - 100 × 10-5%) and pH values (7-9), they showed remarkable antioxidative activities. Their activities were much stronger than those of such commercially available natural antioxidants as ascorbic acid, γ-oryzanol, gallic acid, L-tryptophan, (+)-catechin and D-α-tocopherol. The hydrogen- or electron-donating activities of procyanidins to the DPPH radical in a 50% ethanol solution were also stronger than those of ascorbic acid and D-α-tocopherol.

Protein Precipitating Capacity of Crude Canola Tannins: Effect of pH, Tannin, and Protein Concentrations

Article

Aug 1996

The protein precipitating capacity of canola tannins was evaluated using the protein precipitation assay of Hagerman and Butler (J. Agric. Food Chem. 1978, 26, 809−812) and the dye-labeled bovine serum albumin (BSA) assay of Asquith and Butler (J. Chem. Ecol. 1985, 11, 1535−1543). Condensed tannins were isolated from hulls of Cyclone, Excel, and Westar canola cultivars. The tannin content in the hulls ranged from 98 to 1973 mg of catechin equivalents/100 g of hulls, as determined by the vanillin assay. The effect of pH on the affinities of dye-labeled and unlabeled BSA, fetuin, gelatin, lysozyme, and pepsin was monitored. The optimum pH for the precipitation of dye-labeled and unlabeled BSA was found to be 3.5 and 4.0, respectively. The optimum pH for the precipitation of proteins was found to be 0.3−3.1 pH units below the isoelectric points of the proteins. The crude tannin extracts contained about 20% proanthocyanidins, which were soluble in ethyl acetate as determined by the vanillin assay. Canola tannins showed definitive thresholds prior to the formation of insoluble tannin−protein complexes as determined by the protein precipitation assay. There was also a linear correlation (r2 = 0.975) between the amount of tannin−protein complex formed and the amount of tannin added to the system. Ethyl acetate soluble proanthocyanidins contributed to the protein-precipitating capacity of crude canola tannins isolated from low-tannin Cyclone canola hulls. Keywords: Condensed tannins; canola; hulls; tannin−protein interactions

Protein precipitation method for the quantitative determination of tannin

Article

Jul 1978

The tannin content of crude plant exts. or of purified prepns. was detd. by adding the sample to a std. soln. of protein, isolating the insol. tannin-protein complex, dissolving it in alk. soln., and measuring the absorbance at 510 nm after adding FeCl3. Plots of absorbance as a function of the amt. of tannin are linear for 0.20-1.0 mg tannic acid and partially purified sorghum tannins. Nontannin components of crude MeOH exts. of sorghum and cowpeas do not interfere with the assay. The results of the pptn. method are qual. similar to those obtained by vanillin assay. The pptn. assay can be used to study the effects of pH and other parameters on tannin-protein interactions

A Critical Evaluation of the Vanillin Reaction as an Assay for Tannin in Sorghum Grain

Article

May 1978

Several parameters of the vanillin assay were examined to determine which must be most closely controlled to ensure accuracy and reproducibility. A 20-min extraction in methanol was found to be adequate. When corrected for background color, the modified vanillin assay was found to give nearly identical values with those obtained with the regular vanillin assay, except with group II sorghum. The reactions of tannin and catechin, the usual standard, with vanillin were found to differ markedly in reaction kinetics. Assays of purified tannin showed that use of catechin equivalents overestimates tannin content The assay was found to be extremely temperature dependent. Revised procedures for the vanillin assay are presented which give excellent reproducibility.

Tannins: The new natural antioxidants?

Article