www.food.actapol.net pISSN 1644-07γ0 eISSN 1κκλ-λ5λ4 ŹOIμ 10.17γ06/J.AŻS.β016.4.γλ Received: 23.06.2016 Accepted: 31.08.2016 O R I G I N A L P A P E R
EFFECT OF ROASTING DEGREE ON THE ANTIOXIDANT ACTIVITY
OF DIFFERENT ARABICA COFFEE QUALITY CLASSES
Božana Odžaković
1, Natalija Džinić
2, Zoran Kukrić
1, Slavica Grujić
11Faculty of Technology, University of Banja Luka
Stepanović 73, 78000 Banja Luka, Bosnia and Herzegovina
2Faculty of Technology, University of Novi Sad
Cara Lazara 1, 21000 Novi Sad, Serbia
ABSTRACT
Background. Coff ee is one of the most widely consumed beverages in the world, because of its unique sen-sory properties and physiological properties. Coff ee beverages represent a signifi cant source of antioxidants in the consumers’ diet and contribute signifi cantly to their daily intake. The aim of this research was to inves-tigate the eff ect of diff erent roasting degrees on the content of biologically active compounds and antioxidant activity in diff erent quality classes of Arabica coff ee.
Materials and methods. Samples of green Arabica coff ee (Rio Minas) of two quality classes from two pro-duction batches were used for the research. Roasting was carried out at temperatures of 167, 175 and 171°C. The total phenol content (TPC), total fl avonoid content (TŻC), fl avonol content (ŻC) and antioxidant activity (ŹPPH, ABTS) in the coff ee extracts was determined.
Results. This research shows that TPC was signifi cantly higher (P < 0.05) in green coff ee compared to TPC in roasted coff ee, and TPC decreases as the roasting temperature increases. TŻC and ŻC were signifi cantly
lower (P < 0.05) in green coff ee than in roasted coff ee. Źiff erences in TPC between the 1st and βnd classes of
Arabica coff ee were not signifi cant (P > 0.05), while diff erences in TŻC were signifi cant (P < 0.05) only for green coff ee from the second production batch and diff erences in ŻC were signifi cant (P < 0.05) for green cof-fee and for coff ee roasted at 175°C. Roasting temperatures have diff erent infl uences the antioxidant activity (ŹPPH, ABTS) of coff ee and the highest antioxidant activity was determined in coff ee roasted at 171°C. An
exception was 1st class Arabica coff ee roasted at 167°C (ABTS). All samples of 1st class Arabica coff ee had
higher antioxidant activity (ŹPPH, ABTS) compared to βnd class Arabica.
Conclusions. This research shows that the bioactive compounds content and antioxidant activity of diff erent quality classes of Arabica coff ee are dependent on the degree of roasting. TPC decreases when the roasting temperature increases, while TŻC and ŻC also increase. These results indicate that the antioxidant activity of coff ee depends on a variety of bioactive components in coff ee beans. Antioxidant activity largely depends on
the class of coff ee. The coff ee samples of 1st class quality (maximum κ black beans/γ00 g from the sample and
large bean size) had higher antioxidant activity compared to samples of βnd quality class (maximum 1λ black
beans/γ00 g in the sample and medium-sized beans).
INTRODUCTION
Żood and certain food components can signifi cantly aff ect human health (Źziki et al., β015). A diet that includes fruits, vegetables, cereals and legumes rep-resents a source of many antioxidants (Yashin et al., β01γ). Products which can supply high amounts of antioxidants are beverages such as coff ee, tea, cocoa, wine and beer (Sikora et al., β00κ). Coff ee is one of the most popular beverages worldwide. The type of coff ee beverage, size of the standard cup and the amount of coff ee consumed can signifi cantly vary by geographi-cal region and on an individual basis. Moderate coff ee consumption is associated with a signifi cant reduc-tion in the risk of certain chronic diseases developing (Cavin et al., β00κ). Żor this reason, in recent years, in-creased attention has been directed to the study of cof-fee’s benefi cial eff ects on human health. Since coff ee contains signifi cant amounts of antioxidants and other positive active components, researchers have indicated the potential benefi cial health eff ects of coff ee (Mišik et al., β010ś Nicoli et al., 1λλ7ś Trandafi r et al., β01γ). Svilaas et al. (β004) and Votavova et al. (β00λ) con-fi rmed that coff ee beverages contribute 66% of the to-tal antioxidant intake. Recent studies have shown that coff ee components such as tocopherols, carotenoids, caff eine, phenolic compounds such as chlorogenic acid, hydroxycinnamic acid and products of the Mail-lard reaction, such as melanoides, have antioxidant properties (Parras et al., β007ś Vignoli et al., β011). Phenolic compounds are considered to be the most ef-fective antioxidants, and also they have a signifi cant infl uence on the stability, sensory and nutritional char-acteristics of the product (Klensporf-Pawlik and Przy-bylski, β015ś Sikora et al., β00κ). Phenolic acids, their derivatives and some fl avonoids belong to the group of natural phenolic compounds (Sikora et al., β01β). Cof-fee roasting is a complex heat transfer process and this step is probably the most important stage in coff ee pro-cessing (Żereez źduzan, β015ś Noor Aliah, β015). The beans undergo a series of reactions during roasting, leading to the desired changes in physical properties and chemical composition (Illy and Viani, β005). The concentration of highly active phenolic compounds in green coff ee depends on coff ee variety and origin, while the level in coff ee as a beverage depends on the roasting degree and method of beverage preparation.
Phenolic components are partially decomposed during the roasting process and depend on the roasting condi-tions (Żarah and Źonangelo, β006).
The antioxidant activity of coff ee of diff erent types and origin was the subject of many previous studies. However, to the best of our knowledge, no data exists on the antioxidant activity of coff ee of diff erent qual-ity classes, nor on fl avonol content in coff ee. The aim of this research was to investigate the eff ect of diff er-ent roasting degrees on biologically active compound content and antioxidant activity in diff erent quality classes of Arabica coff ee. Żor that purpose, the total phenol, total fl avonoid and fl avonol content, as well as antioxidant activity were determined in the green and roasted coff ee samples. Researching the possible correlations between the content of these compounds and antioxidant activity are also included in the scope of this study.
MATERIALS AND METHODS
Coff ee samples and roasting conditions
żreen coff ee samples, Arabica (Rio Minas from Brazil, year of harvest β014) of two quality classes from two production batches were used for the research. A local coff ee manufacturer supplied us with green coff ee, as is usually used and available on the local market. The coff ee samples were distinguished by quality class (Table 1). The roasting process was performed in in-dustrial conditions, in a roaster which has a capacity of 150 kg/batch. Roasting was performed at three dif-ferent temperatures (three roasting degrees) according to industrial conditions of production and manufactur-ing specifi cations. Table β presents a breakdown of roasting.
Coff ee extracts preparation
Determination of total phenol content
The total phenol content (TPC) of each coff ee ex-tract was determined spectrophotometrically (UV/ Vis spectrophotometer Perkinźlmer Lambda β5), following the Żolin-Ciocalteu procedure, according to Wolfe et al. (β00γ)’s modifi ed method. 1.5 mL of Żolin-Ciocalteu solution (stock Żolin-Ciocalteu solu-tion dissolved with water in 1/10 ratio) and 1.5 mL of 7.5% NaHCOγ were added to 0.β ml of diluted ex-tract. Absorbance was measured after γ0 min storing (in a dark place and at room temperature) at 765 nm, along with the blank. Chlorogenic and gallic acid were used as standards and the results were expressed
as mg chlorogenic acid equivalents (CżA)/g of cof-fee sample and as mg gallic acid equivalents (żAź)/g of coff ee sample.
Determination of total fl avonoid content
The total fl avonoid content (TŻC) was determined according to method described by Ordoñez et al. (β006). 1 ml of β% AlClγ ethanolic solution was added to 1 ml of diluted extract. The absorbance was measured after γ0 min storing (in a dark place) at 4β0 nm, along with the blank. TŻC was calculated and expressed as mg quercentin equivalents (Qź)/g of the coff ee sample.
Table 1. Samples of Arabica green coff ee and their classifi cation
żreen coff ee
samples żreen coff ee beans classifi cation on “black bean count basis” żreen coff ee beans “sizing chart classifi cation”
Arabica (ż1)*
Rio Minas βnd class N/Y γ/4 – max 1λ black beans/γ00 g of sample SC. 15/16 – medium size Arabica (żβ)*
Rio Minas 1st class N/Y β/γ – max κ black beans/γ00 g of sample SC. 17/1κ – large size Arabica (żγ)**
Rio Minas βnd class N/Y γ/4 – max 1λ black beans/γ00 g of sample SC. 15/16 – medium size Arabica (ż4)**
Rio Minas 1st class N/Y β/γ – max κ black beans/γ00 g of sample SC. 17/1κ – large size
*żreen coff ee samples from the fi rst production batch. **żreen coff ee samples from the second production batch.
Table 2. Temperature regime for coff ee roasting
żreen coff ee
samples Roasted coff ee samples
Parameters of roasting process
Roasting degree
T, °C T, min
Arabica (ż1) A1 167 β5 light
Arabica (żβ) B1 167 β5 light
Arabica (ż1) Aβ 175 β5 dark
Arabica (żβ) Bβ 175 β5 dark
Arabica (żγ) J1 171 β6 medium
Determination of fl avonol content
The fl avonol content (ŻC) was determined according to Kumaran and Karunakaran’s method (β007). 1 mL of β% AlClγ ethanolic solution and 1.5 mL (50 g/L) sodium acetate solutions were added to 1 mL of the diluted extract. Absorption at 440 nm was read after β.5 h storing in a dark place. ŻC was calculated and expressed as mg quercetin equivalents (Qź)/g of the coff ee sample.
Determination of antioxidant activity by the DPPH method
The eff ect of the coff ee extract on ŹPPH radical (β,β-diphenyl-1-1-picrylhidrazyl) was determined by the method described by Liyana-Pathirana and Shaidi (β005). 1 ml of 0.1γ5 mM ŹPPH methanolic solution was added to 1 ml of the diluted extract. The mixture was left in a dark place for γ0 min and absorbance was measured at 515 nm, along with the blank. Trolox was used as the standard and the results were expressed as Trolox equivalent μmol (Tź)/g coff ee sample.
Determination of antioxidant activity by the ABTS method
The Trolox equivalent antioxidant capacity (TźAC) of coff ee extracts was estimated by ABTS radical cation (β,β-azinobis-(γ-ethylbenzothiazoline-6-sulphonic acid) decolourisation assay (Re et al., 1λλλ). The ABTS radicals were generated by reacting an ABTS aqueous solution (7 mM) with KβSβOκ (β.4 mM) then storing it in a dark place for 16 h. A working solu-tion was obtained by diluting the stock solusolu-tion of the ABTS radical cation with methanol to obtain an ab-sorbance of 0.7 ±0.005 at 7γ4 nm. 1 ml of the ABTS solution was added to 1 ml of the diluted extract. The absorbance was measured after 7 min storage (in a dark place) at 7γ4 nm, along with the blank. The results were expressed as Trolox equivalents μmol (Tź)/g coff ee sample.
Statistical analysis
All measurements were carried out in triplicate, and presented as mean ±standard deviation (SŹ). All re-sults were subjected to one-factor analysis of variance (ANOVA) and when Źuncan’s test was performed to estimate the signifi cance of diff erences between mean values at P < 0.05, using Statistica 1β.0 software
(StatSoft, Inc., Tulsa, OK, USA). Correlations be-tween TPC, TŻC, ŻC and antioxidant activity (ŹPPH, ABTS) were assessed by Pearson’s correlation coef-fi cient, and its signicoef-fi cance by the t-test for P < 0.05.
RESULTS AND DISCUSSION
between coff ees of diff erent quality classes roasted at 171°C.
Coff ee samples roasted at 167°C (A1, B1) and 171°C (J1, K1) had signifi cantly higher (P < 0.05) antioxidant activity determined by ŹPPH and ABTS tests compared with the green coff ee samples (ż1, żβ and żγ, ż4) (Tables γ and 4). Hečimović et al. (β011)
determined that the antioxidant activity (ABTS) in light- and medium-roasted Arabica coff ee (Minas) was higher compared to the antioxidant activity of green Arabica coff ee. Coff ee roasted at 175°C had signifi cantly higher (P < 0.05) antioxidant activity determined only by ABTS compared to green cof-fee. All samples of 1st class Arabica coff ee from the Table 3. Content of total phenol, total fl avonoid and fl avonol, and antioxidant activity of green coff ee samples and coff ee samples roasted at 167°C and 175°C
Parameters Mean value ±standard deviation (n = γ)
ż1 żβ A1 B1 Aβ Bβ
TPC, mg CżA/g 4λ.λ0ab
±γ.1λ 51.75
a
±γ.47 46.74
bc
±β.41 44.15
c
±1.04 γ5.0κ
d
±1.04 γ7.κγ
d ±1.β7 TPC, mg żAź/g γ1.65ab
±1.κ4 γβ.7κ
a
±β.07 βλ.κ1
bc
±1.4γ βκ.βκ
c
±0.6β βγ.66
d
±0.κλ β4.54
d ±0.75
TŻC, mg Q/g γ.04d
±0.17 β.λκ
d
±0.07 4.β1
bc
±0.07 4.01
c
±0.β1 4.6γ
a
±0.1β 4.46
ab ±0.1κ
ŻC, mg Q/g 1.17e
±0.11 1.γγ
d
±0.0κ 1.λβ
c
±0.01 1.κ4
c
±0.04 β.γ6
a
±0.1γ β.1γ
b ±0.07 ŹPPH,μmol Tź/g 17λ.βγc
±1.0λ 1λ7.1β
b
±γ.77 β0γ.γκ
b
±4.51 β1β.0κ
a
±4.10 176.44
c
±7.74 β01.γ7
b ±4.6γ ABTS, μmol Tź/g 160.67e
±4.1κ 17β.05
d
±γ.54 β11.0γ
a
±β.40 β15.0λ
a
±4.55 17λ.βκ
c
±β.γ5 β04.61
b ±γ.κ4
TPC – total phenol content. TŻC – total fl avonoid content. ŻC – fl avonol content. a–eValues with diff erent letters in the same row are signifi cantly diff erent at P < 0.05.
Table 4. Content of total phenol, total fl avonoid and fl avonol, and antioxidant activity of green cof-fee samples and coff ee samples roasted at 171°C
Parameters Mean value ±standard deviation (n = γ)
żγ ż4 J1 K1
TPC, mg CżA/g 50.λ1a ±1.1κ 5β.41a ±β.14 40.λ0b ±0.λλ 4β.7βb ±0.44 TPC, mg żAź/g γβ.βκa ±0.70 γ1.1λa ±4.6β βκ.λ6ab ±0.47 β4.λ4b ±0.κ1
TŻC, mg Q/g γ.β7c ±0.0λ γ.57b ±0.17 4.β6a ±0.0λ 4.γ4a ±0.0γ
ŻC, mg Q/g 1.1βc ±0.04 1.γβb ±0.0γ β.04a ±0.04 β.00a ±0.0γ
ŹPPH,μmol Tź/g 1κ5.10b ±γ.κγ 1λβ.14b ±4.4κ ββ6.14a ±4.γ7 ββλ.4βa ±β.βλ ABTS, μmol Tź/g 16λ.1λd ±β.λ4 1λβ.1γc ±1.7κ ββγ.66b ±β.60 ββκ.7λa ±β.γκ
fi rst production batch (żβ, B1 and Bβ) had higher antioxidant activity compared to the βnd class Arabica samples (ż1, A1 and Aβ) (Table γ). The diff erences established were statistically signifi cant (P < 0.05) between all samples except between samples A1 and B1 for the results of the ABTS test (P > 0.05). Based on the results of the ŹPPH and ABTS tests of coff ee samples from the second production batch (Table 4), it was found that 1st class Arabica coff ee had the highest antioxidant activity (ż4 and K1), and βnd class Ara-bica coff ee (żγ and J1) and the diff erences were only signifi cant (P < 0.05) for the results of the ABTS test.
In this research, Arabica green coff ee samples from two production batches were used (Table 1). The absolute values for the diff erences in TPC, TŻC and ŻC and antioxidant activity were calculated between the green coff ee samples and coff ee samples roasted at diff erent temperatures (167°C, 175°C and 171°C). The absolute values represent the diff erences between the values of the parameters examined for green cof-fee samples from the fi rst production batch and coff ee samples roasted at 167°C and 175°Cś and the diff er-ence between the values of the parameters examined for green coff ee samples from the second production batch and coff ee samples roasted at 171°C.
The results indicated that coff ee roasted at 167°C had a higher TPC (mg CżA/g and mg żAź/g) than coff ee roasted at 171°C and 175°C. The absolute val-ue Ź1 (|ż1 – A1|) was lower than the absolute valval-ues Źβ (|ż1 – Aβ|) and Ź5 (|żγ – J1|) and absolute value Źγ (|żβ – B1|) was lower than the absolute values Ź4 (|żβ – Bβ|) and Ź6 (|ż4 – K1|) as green coff ee had the highest TPC and it decreases when the temperature of roasting increases. The results are in accordance with the literature data (del Castillo et al., β00βś Perez-Her-nandez et al., β01βś Sacchetti et al., β00λś Trandafi r et al., β01γś Vignoli et al. β011).
Coff ee roasted at 167°C had a higher TŻC (mg Q/g) than coff ee roasted at 171°C. Coff ee roasted at 175°C had a signifi cantly higher (P < 0.05) TŻC (mg Q/g) than coff ee roasted at 167°C and 171°C. The ab-solute value Ź1 (|ż1 – A1|) was higher than the abso-lute value Ź5 (|żγ – J1|), and the absoabso-lute value Źβ (|ż1 – Aβ|) was higher than the absolute values Ź1 (|ż1 – A1|) and Ź5 (|żγ – J1|). The absolute value Źγ (|żβ – B1|) was higher than the absolute value Ź6 (|ż4 – K1|). The absolute value Ź4 (|żβ – Bβ|) was higher
than the absolute values Źγ (|żβ – B1|) and Ź6 (|ż4 – K1|). TŻC decreases with the temperature increase during roasting at 171°C, and with a further increases in roasting temperature (at 175°C), TŻC increases. Hečimović et al. (β011) also found the highest TŻC in dark-roasted Arabica coff ee (Minas) and the lowest TŻC was in medium-roasted Arabica coff ee. Coff ee roasted at 167°C had a signifi cantly lower (P < 0.05) ŻC (mg Q/g) than coff ee roasted at 171°C and 175°C. The absolute value Ź1 (|ż1 – A1|) was lower than the absolute values Źβ (|ż1 – Aβ|) and Ź5 (|żγ – J1|) and absolute value Źγ (|żβ – B1|) was lower than abso-lute values Ź4 (|żβ – Bβ|) and Ź6 (|ż4 – K1|) because green coff ee had the lowest ŻC, and fl avonol content increases when the roasting temperature increases.
temperature (167°C) will have the highest antioxidant activity level. However, the antioxidant activity of roasted coff ee depends on the phenolic fractions that decrease during roasting, and also depends on non--phenolic fractions, which increase during the roast-ing process, due to the formation of Maillard reaction products (Sacchetti et al., β00λ). According to Nicoli et al. (1λλ7), the antioxidant activities of compounds formed during coff ee roasting do not linearly increase as the temperature or roasting degree increases, which
indicates that diff erent compounds with antioxidant properties were formed during heat treatment.
Correlations between the content of total phenol, total fl avonoid and fl avonol and antioxidant activity were calculated (Table 6). Signifi cant correlations (P < 0.05) were evident between TPC [mg CżA/g] and antioxidant activity (ŹPPH and ABTS) and be-tween TPC [mg żAź/g] and antioxidant activity determined with ABTS. Correlations between TPC [mg żAź/g] and antioxidant activity determined with ŹPPH wasn’t signifi cant (P > 0.05). In corre-lations between total fl avonoid and fl avonol content and antioxidant activity, Pearson linear correlation coeffi cients were negative but statistically signifi cant (P < 0.05).
CONCLUSION
The results obtained in this study provide an overview of the eff ect of diff erent roasting temperatures on total phenol content, total fl avonoid content and fl avonol content as well as on the antioxidant activity in dif-ferent quality classes of Arabica coff ee. Total phenol content was highest in green coff ee, and it decreases as the roasting temperature increases. Total fl avonoid content and ŻC were highest in coff ee roasted at 175°C (dark roasting degree). Total fl avonoid content and ŻC increases as the roasting temperature increases. The highest antioxidant activity (ŹPPH and ABTS) was Table 5. Absolute values for changes in total phenol, total fl avonoid and fl avonol, and antioxidant activity be-tween green coff ee and coff ee roasted at 167°C, 175°C and 171°C
Parameters Mean value (n = γ)
Ź1 Źβ Źγ Ź4 Ź5 Ź6
TPC, mg CżA/g γ.16c 14.κβa 7.60bc 1γ.λ6a 10.01ab λ.6λab
TPC, mg żAź/g 1.κ4b 7.λλa 4.50ab κ.β4a γ.γβab 6.β5ab
TŻC, mg Q/g 1.17bc 1.5λa 1.0γcd 1.4κab 0.λλcd 0.77d
ŻC, mg Q/g 0.75c 1.1λa 0.51d 0.κ0bc 0.λβb 0.6κc
ŹPPH,μmol Tź/g β4.15b β.7λd 14.λ6c 4.β5d 41.04a γ7.βκa
ABTS, μmol Tź/g 50.γ6ab 1κ.61e 4γ.04bc γβ.56d 54.47a γ6.66cd
Ź1 = |ż1 – A1|. Źβ = |ż1 – Aβ|. Źγ = |żβ – B1|. Ź4 = |żβ – Bβ|. Ź5 = |żγ – J1|. Ź6 = |ż4 – K1|. Ź1–Ź6 – absolute values for changes of examined parameters, between green coff ee and coff ee roasted at 167°C, 175°C and 171°C. a–eValues with diff erent letters in the same row are signifi cantly diff erent at P < 0.05.
Table 6. Correlations between content of total phenol, total fl avonoid and fl avonol, and antioxidant activity
ŹPPH, μmol Tź/g ABTS, μmol Tź/g
TPC, mg CżA/g 0.50κ5
P < 0.05* P < 0.050.6446 *
TPC, mg żAź/g 0.γ77λ
P > 0.05* (ns)
0.4744 P < 0.05*
TŻC, mg Q/g –0.4κ74
P < 0.05* P < 0.05–0.61γ5 *
ŻC, mg Q/g –0.6γ15
P < 0.05* P < 0.05–0.71λ7 *
TPC – total phenol content. TŻC – total fl avonoid content. ŻC – fl avonol content.
determined in coff ee roasted at 171°C (medium roast-ing degree). An exception was 1st class Arabica coff ee roasted at 167°C (ABTS). These results indicate that the antioxidant activity of coff ee depends on a variety of bioactive components in coff ee beans, whose con-centration depends on the conditions of coff ee roast-ing. The diff erences in TPC between 1st and βnd classes of Arabica coff ee weren’t signifi cant (P > 0.05), while the diff erences in TŻC were signifi cant (P < 0.05) only for green coff ee from the second production batch, and the diff erences in the ŻC were signifi cant (P < 0.05) for green coff ee and for coff ee roasted at 175°C. These results indicated that antioxidant activity largely de-pends on the class of coff ee, as 1st qualityclass cof-fee (maximum κ black beans/γ00 g of the sample and large size of beans) had higher antioxidant activity compared to the samples of the βnd quality class (max 1λ black beans/γ00 g of the sample and medium size of beans).
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