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INTERNATIONAL JOURNAL OF FOOD AND NUTRITIONAL SCIENCES

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178

ISSN 2319 – 1775 www.ijfans.com

Volume 01, Issue 01, Oct-Dec 2012

@ 2012 IJFANS. All Rights Reserved

Research Paper Open access

FORMULATION AND OPTIMIZATION OF HERBAL TEA

P.Nazni* and S.Vimala Department of Food Science, Periyar University, Salem, Tamilnadu, India

*Corresponding author: [email protected]

ABSTRACT Roselle (Hibiscus sabdariffa Linn.) is a tropical plant widely cultivated in Thailand and locally known as Krachiap

Daeng. Roselle calyx contains a rich source of dietary fiber, vitamins, minerals and bioactive compounds such as organic acids,

phytosterols, and polyphenols, some of them with antioxidant properties. The calyces are rich with anthocyanins and used for

making jelly, jam, preserve and beverages. Roselle anthocyanins are a good source of antioxidants as well as a natural food

colourant. The dried Roselle Calyces were purchased from a local market in Salem. The dried calyces were put in the hot water

at different ratios for a period of 15mts. After the hot water extraction the calyces were filtered and cooled well. Sugar

concentration like 11, 12, 13 and 14% were added to the final product.

Key words: Roselle, calyx, antioxidants, polyphenols.

INTRODUCTION

Roselle (Hibiscus sabdariffa Linn.) is a tropical

plant widely cultivated in Thailand and locally known as

Krachiap Daeng. Roselle can be found in almost all warm

countries such as India, Saudi Arabia, Malaysia, Thailand,

Philippine, Vietnam, Sudan, Egypt, Mali and Mexico

(Quezon 2005, Amin 2008). Roselle calyx contains a rich

source of dietary fiber, vitamins, minerals and bioactive

compounds such as organic acids, phytosterols, and

polyphenols, some of them with antioxidant properties. The

phenolic content in the plant consists mainly of anthocyanins

like delphinidin-3-glucoside, sambubioside, and cyanidin- 3-

sambubioside mainly contributing to their antioxidant

properties (Aurelio et al 2007). The roselle plant parts have

also been reported to be folk remedy for cancer, obesity,

diabetes and hypertension (Hirunpanich et al 2006, Adhikari

et al 2004, Aurelio et al 2007).

The calyces are rich with anthocyanins and used for

making jelly, jam, preserve and beverages (Hirunpanish et

al., 2006). Roselle anthocyanins are a good source of

antioxidants as well as a natural food colourant. (Adhikari et

al., 2004).The water extract of the red flowered species of

Roselle is widely used in the preparation of fruit drink

because of its unique and appealing characteristic color and

flavor (Fasoyiro et al 2005). The increased consumer

awareness of food quality has emphasized the need to

optimize the drying process (Banga et al 1994). The response

surface methodology (RSM) is a useful technique, for the

investigation of complex processes. It has been successfully

applied to optimize food process operations (Box et. al

1978).

MATERIALS AND METHODS

The dried Roselle Calyces were purchased from a

local market in Salem.

Hot water (100o ± 2

oC)

↓ Dried Roselle calyces → Calyces Hot water mixing at

different ratios ↓

Hot water extraction for different duration ↓

Filtration ↓

Cooling ↓

Unsweetened Herbal Tea14 % sugar concentration ↓

Sweetening (11, 12, 13 & 14% concentration) ↓

Final product (Sweetening Herbal Tea) Fig 1: Steps involved in the Process of Herbal (Roselle)

Tea production

OPTIMIZATION OF HOT WATER EXTRACTION IN

THE PRODUCTION OF HERBAL (ROSELLE) TEA

Response surface Methodology (optimization) is

more advantageous then the traditional single parameter

optimization in that it saves time, space and raw materials.

The totals of 20 runs are needed for optimizing the five

individual parameters in the current CCD.

In this study 3 factors including the water (X1),

extraction time (X2), Sample (X3). The coded as -1 0 +1 are

set up according to the results of single factor experiments.

The optimization data are fitted to a second order

polymerical regression model which contains the coefficients

of linear quadratic and interaction effects.

FORMULATION AND OPTIMIZATION OF HERBAL TEA P.Nazni and S.Vimala


179

FINDINGS

The Herbal (Roselle) tea prepared with the help of

Roselle powder and was characterized for its

physicochemical characteristics. The colour intensity (Y1),

pH (Y2), Ascorbic acid (Y3), Total solids (Y4), Total Titrable

Acidity (Y5) was measured as response variables. The colour

intensity of herbal (Roselle) tea was ranged from 0.301-

1.367, pH 4.29-6.80, Ascorbic acid 25.20-29.87, Total solids

1.14-3.47, Total Titrable Acidity 0.269-1.440 respectively in

Herbal(Roselle)Tea.

DIAGNOSTIC CHECKING OF FITTED MODEL AND

SURFACE PLOT FOR ALL Y RESPONSES

Regression analysis indicated that the fitted quadratic model

accounted that about 47% for colour intensity, 30% for pH,

50% for ascorbic acid, 39% for Total Solids, 29% for Total

Titrable Acid. The values of regression coefficients, sum of

squares and P values for coded form of process variables are

presented in Table 3.

Table – 1- Observed values of dependent variables for Herbal (Roselle) Tea in different runs of optimization

experiment Powder incorporated

Symbol Independent

variables Range & levels

X1 Water 52 57 62

X2 Extraction time 20 25 30

X3 Sample 3 5 7

Design point Uncoded Coded

X1 X2 X3 x1 x2 x3

1 52 20 3 -1 -1 -1

2 62 20 3 +1 -1 -1

3 52 30 3 -1 +1 -1

4 52 20 7 -1 -1 +1

5 62 20 7 +1 -1 +1

6 52 30 7 -1 +1 +1

7 62 30 7 +1 +1 +1

8 52 25 5 -1 0 0

9 62 25 5 +1 0 0

10 57 20 5 0 -1 0

11 62 25 5 +1 0 0

12 57 20 5 0 -1 0

13 57 30 5 0 +1 0

14 57 25 3 0 0 -1

15 57 25 3 0 0 -1

16 57 25 7 0 0 +1

17 57 25 7 0 0 +1

18 57 25 7 0 0 +1

19 57 25 7 0 0 0

20 57 25 7 0 0 +1

The colour intensity, pH, Ascorbic acid, Total solids, Total Titrable Acidity were taken as Y responses.

Table-2 - Physico-chemical Properties of Herbal Tea

Uncoded value

SL.NO X1 X2 X3 Colour

Intensity

(OD)

pH Ascorbic

acid

(mg/100ml)

Total

Solids

(%)

Total

Titrable

Acidity (%)

1 52 20 3 0.773 5.59 25.31 2.48 0.603

2 62 20 3 0.612 5.36 25.23 2.50 0.504

3 52 30 3 0.682 4.96 25.20 3.01 0.407

4 52 20 7 0.750 4.29 29.17 3.43 0.301

5 62 20 7 0.987 5.48 29.87 3.42 0.322

6 52 30 7 0.980 5.55 29.39 3.39 0.338

7 62 30 7 0.977 5.79 29.42 3.47 0.341

8 52 25 5 0.510 6.37 25.84 2.84 0.921

9 62 25 5 0.644 6.65 25.86 1.69 1.401



180

10 57 20 5 0.590 6.80 26.96 1.40 1.032

11 62 25 5 0.557 6.63 26.79 1.71 1.440

12 57 20 5 0.589 6.71 26.81 1.14 1.035

13 57 30 5 0.478 6.72 26.70 1.14 0.963

14 57 25 3 0.301 6.79 25.41 2.81 0.960

15 57 25 3 0.306 6.62 25.24 2.83 0.273

16 57 25 7 1.367 5.02 29.72 3.42 0.278

17 57 25 7 1.360 5.00 29.61 3.40 0.269

18 57 25 7 1.365 5.02 29.62 3.41 0.269

19 57 25 7 1.361 5.02 29.71 3.42 0.276

20 57 25 7 1.364 5.01 29.61 3.41 0.275

X1 –Water, X2- Extraction Time, X3 – Herbal (Roselle) Tea

Table-3 - Regression coefficient (coded variables) from quadratic model and their significance

Coefficients Colour

Intensity

pH Ascorbic acid Total solids Total

Titrable

Acidity

Model 1.18NS 5.33NS 28.88NS 3.28NS 0.41NS

X1 -0.048NS 1.661NS 0.12NS -0.052NS -0.017NS

X2 -0.028NS -0.032NS -9.985NS 1.009NS -0.035NS

X3 -0.025NS 0.23NS 0.54NS 0.30NS 0.026NS

X12 -0.14NS 0.22NS -0.64NS -0.32NS 0.15NS

X22 -0.15NS 0.20NS -0.50NS -0.36NS 0.15NS

X32 -0.22NS 0.23NS -0.77NS -0.12NS 0.031NS

X1 X2 -0.025NS 8.750NS 0.12NS -0.025NS 0.070NS

X1 X3 -0.048NS 0.19NS -0.99NS -0.14NS 0.10NS

X2 X3 -0.066NS 0.35NS -0.98NS -0.24NS 0.13NS

R2 0.4740 0.2975 0.4966 0.3908 0.2903

Adj R2 0.0005 -0.3348 0.0436 -0.1576 -0.3485

Pred R2 -0.7995 -3.2824 -1.5509 -3.4708 -3.5802

Adeq precision 2.712 2.340 3.772 2.591 2.007

Lack of Fit NS NS NS 1% sig NS

COLOUR INTENSITY

The colour intensity of the developed Herbal

(Roselle) Tea was ranged from 0.301-1.367. The coefficient

of determination R2 was 47% of the regression model. The

developed model for roselle herbal tea in the form of coded

process variables is as follows: Y1 (Colour Intensity) = -

0.048X1-0.028X2-0.025X3 -0.14 X1 2-0.15X2

2-0.22X 3

2-

0.025X1X2 -0.048X1 X3 -0.066X2 X3

The magnitude of P value in Table 4 indicates the

negative contribution for the Water, Extraction and Herbal

(Roselle) Tea. The quadratic terms have negative effect on

colour intensity. The interactions of X1 X2, X1 X3 and X2 X3

have the negative effect on colour intensity. The effect of

Water, Extraction Time and Herbal (Roselle) Tea on the

colour intensity has been shown in Fig 2.

pH

The pH of the developed Herbal (Roselle) Tea was ranged

from 4.29-6.80. The coefficient of determination R2 was 30%

of the regression model. The developed model for herbal tea

in the form of coded process variables is as follows: Y1 (pH)

= 1.661X1-0.032X2+0.23 X3 +0.22 X1 2+0.20X2

2+0.23X 3

2+

8.750X1X2 +0.19X1 X3 +0.35X2 X3


positive contribution for the Water, and Herbal (Roselle) Tea

while negative contribution for extraction. The quadratic

terms have positive effect on pH. The interactions of X1 X2,

X1 X3 and X2 X3 have the positive effect on pH. The effect of

Water, Extraction Time and Herbal (Roselle) Tea on the pH

has been shown in Fig-3.

ASCORBIC ACID

The Ascorbic acid of the developed Herbal





181

Design-Expert® SoftwareFactor Coding: ActualPH

Design points below predicted value6.8

4.29

X1 = A: WaterX2 = B: Extraction Time

Actual FactorC: Sample = 3.00

20.00

22.00

24.00

26.00

28.00

30.00

52.00

54.00

56.00

58.00

60.00

62.00

4

4.5

5

5.5

6

6.5

P

H

A: Water B: Extraction Time

5.10355.1035

Design-Expert® SoftwareFactor Coding: ActualTotal Titrable Acidity(%)

Design points below predicted value1.44

0.269



20.00

22.00

24.00

26.00

28.00

30.00

52.00

54.00

56.00

58.00

60.00

62.00

0.2

0.4

0.6

0.8

1

1.2

T

ota

l T

itra

ble

Ac

idit

y(%

)


0.383150.38315

developed model for Herbal (Roselle) tea in the form of

coded process variables is as follows: Y1 (Ascorbic acid) =

0.12X1-9.985X2+0.54X3 -0.64 X1 2-0.50X2

2-0.77X 3

2+

0.12X1X2 -0.99X1 X3 - 0.98X2 X3


positive contribution for the Water, and Herbal (Roselle) Tea

while negative contribution for extraction. The quadratic

terms have negative effect on ascorbic acid. The interactions

of X1 X2, have the positive effect on ascorbic acid while the

Optimum value of process parameters and responses Process

Parameters

Target Experimental

Design

Importance Optimum

values

Desirability

Water(ml) In range 52 62 3 60.29

0.592

Extraction

Time (min)

In range 20 30 3 27.13

Sample(g) In range 3 7 3 3

Responses Predicted Values

Colour

Intensity (O.D)

Minimize 0.301 1.36 3 0.85

pH Minimize 4.29 6.8 3 5.17

Ascorbic acid

(mg/100ml)

Maximize 25.2 29.87 3 28.37

Total solids

(%)

Maximize 1.16 3.48 3 2.81

Total Titrable

Acidity (%)

Minimize 0.269 1.44 3 0.383

interactions of X1 X3 and X2 X3 have the negative effect on

ascorbic acid. The effect of Water, Extraction Time and

Herbal (Roselle) Tea on the ascorbic acid has been shown in

Fig-4.

TOTAL SOLIDS

The Total Solids of the developed Herbal (Roselle)

Tea was ranged from 1.14 -3.47. The coefficient of

determination R2 was 39% of the regression model. The


coded process variables is as follows: Y1 (Total Solids) = -

0.052X1+1.009X2+ 0.30X3 -0.32 X1 2-0.36X2

2-0.12X 3

2-

0.025X1X2 -0.14X1 X3 -0.24X2 X3

The magnitude of P value in Table 4 indicates the negative

contribution for the Water, while positive contribution for

fig 2 3D effect of (colour intensity) response

fig-3 3D effect of (pH) response

Design-Expert® SoftwareFactor Coding: ActualAscorbic acid (mg/100ml)

29.87

25.2



20.00 22.00

24.00 26.00

28.00 30.00

52.00 54.00

56.00 58.00

60.00 62.00

24

25

26

27

28

29

A

sc

orb

ic a

cid

(m

g/1

00

ml)


28.635728.6357

Fig-4-3D effect of (Ascorbic acid mg)

responses

Design-Expert® SoftwareFactor Coding: ActualTotal solids(%)

Design points above predicted value3.48

1.14



20.00

22.00

24.00

26.00

28.00

30.00

52.00

54.00

56.00

58.00

60.00

62.00

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

T

ota

l s

olid

s(%

)


3.267243.26724

Fig-5-3D effect of (total solid %) responses Fig-6-3D effect of (Total Titrable acidity %)

responses

Design-Expert® SoftwareFactor Coding: ActualColour intensity(optical density)

Design points above predicted value1.367

0.301



20.00

22.00

24.00

26.00

28.00

30.00

52.00

54.00

56.00

58.00

60.00

62.00

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

C

olo

ur

inte

ns

ity

(op

tic

al

de

ns

ity

)


0.471666



182

extraction and Herbal (Roselle) Tea . The quadratic terms

have negative effect on Total Solids. The interactions of X1

X2, X1 X3 and X2 X3 have the negative effect on Total Solids.

The effect of Water, Extraction Time and Herbal (Roselle)

Tea on the pH has been shown in Fig-5.

TOTAL TITRABLE ACIDITY

The Total Titrable Acidity of the developed Herbal




coded process variables is as follows: Y1 (Total Titrable

Acidity) = -0.017X1-0.035X2+ 0.026X3 +0.15 X1 2+0.15X2

2+0.031X 3

2+ 0.070X1X2 +0.10X1 X3 +0.13X2 X3. The

magnitude of P value in Table 4 indicates the negative

contribution for the Water and extraction while positive

contribution for Herbal (Roselle) Tea. The quadratic terms

have positive effect on Total Titrable Acidity. The

interactions of X1 X2, X1 X3 and X2 X3 have the positive

effect on Total Titrable Acidity. The effect of Water,

Extraction Time and Herbal (Roselle) Tea on the pH has

been shown in Fig-6. For the optimization variables, the

responses, that is Colour Intensity(O.D) , pH, Ascorbic acid

(mg/100ml), Total solids(%),Total Titrable Acidity(%) and

overall acceptability respectively were selected on the basis

that these responses had direct effect on the acceptability and

quality of Herbal(Roselle)Tea. To consider all the responses

simultaneously for optimization, the multiple regression was

used to get compromise optimum conditions and it as found

that the scores were 60.29ml, 27.13 min, 3g, 0.85 O.D,

5.17pH, 28.37mg/100ml, 2.81%, 0.383% for Water(ml),

Extraction Time (min),Sample(g), Colour Intensity(O.D) ,

pH, Ascorbic acid (mg/100ml), Total solids(%),Total

Titrable Acidity(%) and overall acceptability respectively.

CONCLUSION Response Surface Methodology (RSM) was used

successfully to optimize the level of Water, Extraction Time,

Sample, for the development of Herbal (Roselle)Tea. Among

all the responses it was found that optimum conditions were

60.29ml, 27.13 min, 3g, 0.85 O.D, 5.17pH, 28.37mg/100ml,

2.81%, 0.383% for Water(ml), Extraction Time

(min),Sample(g), Colour Intensity(O.D) , pH, Ascorbic acid

(mg/100ml), Total solids(%),Total Titrable Acidity(%) and

overall acceptability respectively.

ACKNOWLEDGEMENT

The authors are very much thankful to Indian

Council of Medical Research (ICMR) (File.no:

5/9/7/9026/2011-RHN, Dated: 20th

March, 2012) for

providing funding assistance to conduct their research work.

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Amin I, Emny Haida KI, Mohd-Nazri HS 2008. Roselle

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AND NUTRITIONAL SCIENCES - IJFANS - International … · AND NUTRITIONAL SCIENCES ... The calyces are rich with anthocyanins and used for making jelly, ... optimization in that it