Design, formulation and evaluation of green tea chewing gum

Abstract

Background:

The main purpose of this study is to design, formulate and evaluate the green tea gums with a suitable taste and quality in order to produce an anti-oxidant chewing gum.

Materials and Methods:

Fresh green tea leaves obtained from Northern Iran for extraction. Maceration is the extraction method that is used in this study. The contents of caffeine, catechin and flavonoids of the hydro alcoholic extract were measured. Various formulations of the 120 mg green tea extract chewing gums with different sweeteners, flavoring agents and various gum bases were prepared afterward release pattern, content uniformity, organoleptic results and other properties were characterized.

Results:

The contents of caffeine, catechin and flavonoid of the hydro alcoholic extraction were 207.32 mg/g, 130.00 mg/g and 200.82 mg/g, respectively. Release pattern of green tea chewing gum with different gum base ratios and various sweeteners in phosphate buffer were prepared. A total of 60 persons who were 20-30 years of age, participated in our panel test for organoleptic properties such as taste, stiffness, stickiness, etc., Acceptable gum was the one with the same ratio of the used rubber bases. Cinnamon selected as the preferred taste by volunteers. Combination of aspartame, sugar and maltitol has appropriate taste. The effect of various sweetener on release pattern was negligible, on the other hand rubber bases ratio variation, changed the release pattern obviously.

Conclusion:

The green tea chewing gum with sugar, maltitol and aspartame sweeteners and cinnamon flavor, using the same rubber bases ratio may be a desirable antioxidant product.

INTRODUCTION

Several studies have been reported the effect of green tea consumption on health enhancement and prevention of cancer. Scientists’ investigations on medium culture and animal studies confirm these results.[1] The beneficial effects of green tea leaves including prevention of cardiovascular diseases and cancer are originated from tea polyphenol derivatives, including catechin with anti-oxidant effects. These compounds have free radical-scavenging activities. Free radical-mediated damage to DNA has been found in different cancer tissues.[2] Effective ingredients of green tea are useful to inhibit the carcinogenic stimuli, caused by ultraviolet (UV) radiations and carcinogenic chemicals. These ingredients have the protection role against lung, skin, oral cavity, esophagus, stomach, liver, pancreas, bladder, small intestine, colon, prostate and breast cancers.[1,3] Furthermore, prevention of incidence of diabetes mellitus type II, cardiovascular disease, stroke and heart failure, hypertension, hyperlipidemia, stress reduction and providing cavity hygiene by green tea ingredients are reported.[4,5]

Chemicals in green tea consist of polyphenols, caffeine and etc., Moreover, green tea leaves contain flavonoids, which are anti-oxidant. These flavonoids are effective in reducing inflammation, having antibacterial effect and preventing dental caries. Green tea consumption is diuretic, due to its caffeine content. In addition, because of theophylline contents, they can have therapeutic effects on respiratory diseases such as asthma.[4] Polyphenols exhibit in vitro antibacterial activity against periodontal pathogens; furthermore, they increase the anti-oxidant ability of oral fluids and prevent from periodontal diseases, moreover the polyphenol compounds decrease inflammation by creating an impenetrable layer with protein or polysaccharide.[6]

The anti-oxidant effects of catechin in green tea are more than the one of vitamin C and E, tocopherol and carotene.[4] Constituent materials in green tea causes tranquility by stimulating the gamma-aminobutyric acid (GABA) receptors in human central nervous system (CNS).[7] The active ingredients in green tea are also effective in weight loss that prevents diabetes mellitus and cardiovascular diseases in the long-term.[8]

Green tea is found in edible forms including raw form, 100, 250 and 500 mg tablets, 125, 675 and 850 mg chewable tablets, 100, 150, 175, 315, 333, 383 and 500 mg capsules, 600 mg caplets and in edible forms including topical lotions, creams, ointments and topical gels. Among these forms, the chewing gum form is missed.

Chewing gum form has predictable effects and lower side-effects, due to controlled drug release.[9] It increases sustained alertness and cognition while reduces chronic stress.[10] In comparison with tablets, chewing gum has fewer undesirable effects on CNS system performance and consciousness.[11] The time required for effecting the drug is faster in the case of chewing gum and the level of medicine in blood is hold steady for a long time in comparison with tablets.[12] This form of the drug is more acceptable by consumers, furthermore applying flavoring agents can increase acceptance.[12] Chewing gum form can better maintain the active ingredients, oxidable excipients and water absorber materials with an appropriate coating.[12] It also increases alertness, decreases tiredness and sleepiness.[13] Chewing gum form can be helpful in cleaning teeth surface while chewing and prevents forming teeth plaques[14] and helps dental cavity hygiene.[11,15,16]

Achievement of nicotine chewing gum in 1982,[17] introduced chewing gums as a new drug delivery system. For the first time in 1998, monographs of medicated chewing gums, accepted by European Pharmacopoeia as a pharmaceutical dosage form.[18] Nowadays these chewing gums are produced with a high standard as well as tablets. Today they can be formulated with various drug release profiles, while they are acceptable amongst different patients and clinicians.

Due to the importance of green tea and the presence of standard amounts of anti-oxidants of catechin, caffeine and flavonoid and the cancer prevention effects of these ingredients and the direct effect of green tea on preventing lots of diseases such as cardiovascular, weight gain, diabetes treatment and etc., the absence of green tea chewing gum among different types of green tea in the market is feeling. The main purpose of this study is to design, formulate and prepare the green tea chewing gum containing 10% of thickened green tea extraction, which in addition of being medicine, can be used as a natural anti-oxidant against disease and is acceptable by everyone including children.

MATERIALS AND METHODS

Materials

Gum bases such as elvasti, fruit C, 487 and stick were obtained from Gilan Ghoot Company, (Rasht, Iran). Flavoring agents of eucalyptus, cinnamon, peppermint and banana were from Goltash Company, (Isfahan, Iran) and flavoring agent of cherry from Farabi Pharmaceutical Company (Isfahan, Iran). Dried green tea leaves, which were the product of April 2011, received from Noor Jafari Company (Lahijan, Iran).

Materials such as maltitol, xylitol, aspartame, glycerol, aluminum chloride, potassium acetate, potassium dihydrogen phosphate, sodium hydroxide, glacial acetic acid, magnesium oxide, methanol, chloroform and perchloric acid prepared from Merck Company (Germany). Dimethylamino cinnamaldehyde and Quercetin from Sigma-Aldrich Company (America) were prepared.

Methods

Green tea extract

Hydro-alcoholic extract of green tea obtained through maceration with 70% ethanol for 5 days. Alcohol of the extraction was removed on a rotary evaporator at 50°C. The residue was heated in a water bath at 40°C for further thickening. Quantification of caffeine, catechin and flavonoid contents in the extracted samples were then performed.[19]

Quantification of caffeine content in green tea extract

The caffeine content of green tea extracts was determined using spectrophotometric method. 3 g of magnesium oxide was added to 1 g of each prepared samples; 15 ml of boiling water were added to the mixture and allowed to stand in stirred boiling manner for 10 min. This mixture was then filtered using Whatman No 4 to obtain a clarified extract. Filtrate diluted with boiling water to a volume of 100 ml. 10 ml of buffered bisulphate solution (pH 6.0), which was diluted to 50 ml with water, was added to a 20 ml of an aliquot of the clarified extract and labeled solution “A”. Another 20 ml of the clarified extract was placed in a separatory funnel and further extracted with 15 ml of chloroform. The chloroform was discarded and the residual contents of the separatory funnel were transferred to a beaker. The residual chloroform was removed by placing the beaker with its contents in a microwave oven set at 100°C for 5 min. The contents of the beaker were transferred to a calibrated flask and diluted with water to the 50 ml mark. This was labeled solution “B”.

The absorbencies of solutions A and B were measured using a UV-visible (UV-VIS) spectrophotometer (Shimadzu, UVmini-1240) against distilled water at specific wavelengths. Caffeine content of a sample can be calculated using:

Where C, W and V are caffeine content, weight of product sample (g) and volume of clarified extract (ml), respectively. E_a and E_b are absorbances for solutions A and B, respectively and can be calculated from:[20]

Quantification of catechin content in green tea extract

In order to prepare the samples for catechin analysis, 100 mg of green tea powder was refluxed at 70°C with 25 ml of 70% methanol for 45 min. The reflux was allowed to cool. It was then centrifuged and 1 ml of the particle-free supernatant was diluted with 70% methanol to the volume of 10 ml. In order to prepare the reagent, 26 mg of dimethylamino cinnamaldehyde was added to 25 ml of a mixture of 20 ml methanol, 2.5 ml perchloric acid and 2.5 ml water. Finally, 0.2 ml of the prepared sample was mixed with 0.5 ml of the prepared reagent and diluted with methanol to the volume of 5 ml. The UV absorption of the final prepared solution after 1.5 h was measured at 637 nm against 0.5 ml reagent, which was diluted with methanol to the volume of 5 ml as the blank. The quantity of catechin was calculated using an extinction coefficient of E (1%, 1 cm) = 141.[21]

Quantification of flavonoid content in green tea extract

The aluminum chloride colorimetric method was used.[22] Quercetin as a flavonoid was employed to make the calibration curve. First of all 10 mg of quercetin was dissolved in 80% ethanol and then diluted to the volume of 10 ml. After that the solutions of 2.5, 5, 10, 15, 20 and 25 μg/ml were prepared. 0.5 ml of the diluted standard solutions were separately mixed with 1.5 ml of 95% ethanol, 0.1 ml of 10% aluminum chloride, 0.1 ml of 1 molar potassium acetate and 2.8 ml of water. After incubation at room temperature for ½ h, the absorbance of the mixture was measured at 415 nm with the UV-VIS spectrophotometer. To prepare the blank solution, all substances except quercetin were used and 10% aluminum chloride was replaced. 10 mg of green tea extract was dissolved in 80% ethanol and then diluted to the volume of 10 ml. Finally, 0.5 ml of that was reacted with 10% aluminum and similar to the standard sample other steps were repeated. The experiment was repeated 3 times and the average of obtained absorbencies was calculated.

Preparation of formulations

First of all, gum bases were carefully weighed and heated up to 70°C in a water bath. Liquid glucose, glycerin and green tea extract was weighed exactly, after that other powders were levigated, added to the gum bases and mixed well. Finally, flavoring agents were added to the prepared mixture at 40°C and left at room temperature to be cooled. In order to attain the green tea chewing gum with desired properties, the formulations listed in Tables 1 and 2 were prepared.

Table 1.

Primary formulations of green tea chewing gum

Table 2.

Secondary formulations of green tea chewing gum

Among the prepared formulations F₁₇ showed better properties, thus for further investigations on the drug release from gum bases, F₂₂ and F₂₃ were prepared.

Weight uniformity test

Single dose chewing gums were analyzed for weight uniformity. 20 samples weighed randomly and they did not differ more than 5% from their average.

Content uniformity test

In order to evaluate the green tea content uniformity of each sample, the content of caffeine in samples selected as the indicator. Firstly, 10 mg of pure caffeine dissolved in 100 ml chloroform then solutions of 5, 10, 15, 20, 25 and 30 μg/ml prepared. The wavelength of maximum absorbance (λ_max) for each standard solution was measured and then standard curve of caffeine standard in chloroform plotted.

For each prepared chewing gum samples, separately 10 specimens of equal weight dissolved in 100 ml of chloroform, centrifuged and absorption measurements were taken at a wavelength of the maximum absorbance of caffeine in chloroform using UV-VIS spectrophotometer.

Drug release test

The caffeine content selected as the indicator, in order to evaluate release of the green tea present in each chewing gum formulations. To gain the standard curve, 10 mg of pure caffeine dissolved in 100 ml of phosphate buffer, pH 6.8 and solutions of 5, 10, 15, 20, 25 and 30 μg/ml prepared. The wavelength of maximum absorbance for each standard solution was measured, after that standard curve of caffeine standard in phosphate buffer, pH 6.8 plotted.

A mastication device, which simulated the chewing gum masticating of human, was applied for drug release investigation. The device consisted of a masticating chamber, capable of holding the gum and the release medium (50 ml of phosphate buffer, pH 6.8) and a piston which stroked the gum (60 strokes per min). Water at 37 ± 0.5°C circulated in the jacket around the masticating chamber to avoid temperature changes. Sampling of mediums was performed at 5, 10, 15, 30, 45 and 60 min of mastication and absorption measurements were taken at a wavelength of the maximum absorbance of caffeine in phosphate buffer, pH 6.8 using UV-VIS spectrophotometer. In order to clarify the release mechanism and use the release results associated with each other, the mean dissolution time (MDT) was calculated by the following expression:[23]

Where j is the sample number, n is the number of dissolution sample times, is the time at the midpoint between t_j and t_j-1 which can be calculated with the expression (t_j + t_j-1)/2 and D M_j is the additional amount of drug dissolved between t_j and t_j-1. The MDT is a measure of the rate of the dissolution process; the higher the MDT, the slower the release rate.

Mechanical properties of chewing gums

Tensile investigations were performed on the last prepared formulations F₂₁, F₂₂ and F₂₃ which differed in the contents of gum bases, using a universal testing machine (STM, Santam, Iran). Rectangular shaped tensile samples with a cross-section of 15 × 4 mm² and a gauge length of 50 mm, were fixed on gauges and were stretched under a constant strain rate of 50 mm/min at room temperature until breaking. The stress and strain were calculated based on elongation, applied force, initial sample length and cross section.

Evaluation of organoleptic characteristics of green tea chewing gums

Organoleptic properties such as chewing gum volume, softness/hardness, no stickiness to teeth and taste of different formulated green tea chewing gum tested with various volunteers. 10 trained volunteers tested the volume, softness/hardness, no stickiness to teeth and taste of green tea chewing gums under the supervision of the corresponding author. In order to be comparable, the defined features were assigned numbers of 1-5 using Likert scale.

Evaluation of the green tea chewing gums taste

A taste panel of 20 trained volunteers tested the organoleptic characteristics selected green tea chewing gum formulations, in the next step under the supervision of the corresponding author. In order to select the most desirable flavor by volunteers, a further taste panel performed. In this test, 30 trained volunteers compared the two top flavor of the former step.

RESULTS

Green tea extracts analyzing

About 230 ml of hydro-alcoholic extract of green tea obtained through maceration for 5 days from 100 g of green tea powder dissolved in 800 ml of 70% ethanol. Rotary and water bath were used to further concentration of the hydro-alcoholic extract and then kept refrigerated. A total of three samples of the extract of green tea were analyzed for caffeine, catechin and flavonoid contents, then, the average was calculated. Caffeine content and catechin content obtained 207.32 ± 1.5 mg/g and 130.00 ± 2.3 mg/g, respectively. Extract absorbance at 415 nm was 0.101 in which the flavonoid content calculated 200.82 ± 4.8 mg/g according to the standard curve of absorbance versus quercetin concentration, with the curve equation of y = 0.0061x − 0.0215 (R² = 0.9984).

Green tea chewing gum analysis

Weight uniformity investigation was performed on 20 randomly selected samples and the average weight calculated. The weight of F₁₇ to F_{23 samples} were in the range of 1.19-1.23 g. According to United States Pharmacopeia (USP) standard less than 5% should differ from the average and the results were entirely consistent with this standard.

Drug release analysis was performed separately on three specimens of each F₁₇, F₁₈, F₁₉, F₂₀ and F₂₁ formulations. The standard curve of absorbance versus caffeine in phosphate buffer, pH 6.8 concentration, caused the curve with the equation of y = 0.0672x − 0.0415 (R² = 0.9983) which was used to evaluate the caffeine content of green tea chewing gum in the release medium of phosphate buffer, pH 6.8. The averages of released caffeine during masticating versus time of sampling, with the consideration of 273.2 nm as λ_max, are illustrated in Figures 1 and 2 for samples with different sweeteners in formulations and different gum bases, respectively. The MDT values for F₁₇, F₁₈, F₁₉, F₂₀, F₂₁, F₂₂ and F_{23 samples} were calculated 5.12, 4.98, 4.78, 4.82, 4.85, 3.80 and 5.29, respectively.

Figure 1.

In vitro release of caffeine chewing gum formulations in pH 6.8 phosphate buffer at 37°C with various sweeteners

Figure 2.

In vitro release of caffeine chewing gum formulations in pH 6.8 phosphate buffer at 37°C with various gum bases

A total of 10 separately specimens of each F₁₇ to F₂₃ samples were analyzed for caffeine content uniformity, using the standard curve of absorbance versus caffeine in chloroform concentration with the consideration of 272.0 nm as λ_max, caused the curve with the equation of y = 0.0648x − 0.0260 (R² = 0.9997). The averages of caffeine content in prepared formulations of F₁₇, F₁₈, F₁₉, F₂₀, F₂₁, F₂₂ and F₂₃ samples₈, were 130.5 ± 4.9, 129.3 ± 7.2, 131.8 ± 9.6, 130.9 ± 5.3, 132.2 ± 6.6, 134.1 ± 7.5 and 129.5 ± 9.4 mg/ml, respectively.

The averages of scores allocated by volunteers for each organoleptic property of samples are listed in Table 3. The summations of volunteers allocated scores of two taste panels are listed in Tables 4 and 5.

Table 3.

The averages of scores allocated by volunteers for organoleptic properties of green tea chewing gum formulations by 10 volunteers

Table 4.

The summations of scores allocated by 20 volunteers for each taste of best green tea chewing gum formulations

Table 5.

The summations of scores allocated by 30 volunteers for top tastes of best green tea chewing gum formulations

Tensile behavior of F₂₁, F₂₂ and F₂₃ samples, which consist of various gum bases, are illustrated in Figure 3.

Figure 3.

Tensile behavior of F₂₁, F₂₂, and F₂₃ formulations with various gum bases

DISCUSSION

The caffeine concentration in the green tea extract used in this study was 207.32 ± 1.5 mg/g. As shown by Mulder et al.,[24] the caffeine content of green tea and black tea was 57 and 55 mg/g, respectively. In addition, Vuong et al.[25] reported the value of 95 mg/g for caffeine content in green tea leaves. The difference in the reported caffeine contents and the measured caffeine content in this study may mainly relate to apply green tea extract in this work, in comparison with green tea leaves in other studies. Furthermore, various measuring methods and different source of green tea can be impressive.

The green tea extract used in this study consisted of 130.00 ± 2.3 mg/g catechin. Ye et al.[26] reported the value of 133.25 ± 1.19 mg/g for the total catechin in green tea leaves. As shown by Chandra et al.,[27] the catechin content of green tea leaves was 137.16 ± 5.79 mg/g. Catechin content of green tea leaves in another research by Henning et al.[28] was 204.7 mg/g. Pelillo et al.[29] reported various values of 93, 697 and 757 mg/g for 3 different commercial green tea extracts.

The flavonoid concentration in the green tea extract used in this study was 200.82 ± 4.8 mg/g. Total polyphenol of green tea as Kim et al.[30] reported was in the range of 475.6-811.1 mg/g; While Lee et al.[31] expressed the range of 244.7-368.5 mg/g. Various values may attribute to the different source of green tea and quantification method. Furthermore, in some studies fresh green tea leaves were employed while in this work extract of dried green tea powder was applied.

The extract of dried green tea powder with the above mentioned characteristics used to prepare various formulations of green tea chewing gum. Among lots of ingredients in green tea, caffeine content selected as an indicator of green tea release.

In F₁, F₂, F₃, F₄ and F_{5 samples}, which prepared from green tea powder, the volume of chewing gums were relatively lower, since the powder type substances amount were more than gum bases. They scraped while chewing and were not like a real chewing gum. Changing the gum bases did not resolve the problem. The bitter taste of these chewing gums was obvious. Consequently green tea powder was replaced by green tea concentrated extract in formulations and samples of F₆, F₇, F₈, F₉ and F₁₀ were prepared. Among others the F₁₀ sample with the same amount of gum bases, had better organoleptic properties. However, still the bitter taste was sensible. Adding 4 mg of aspartame to the former resulted F_{11 sample} and mostly covered the bitter taste, although aspartame is one of the most effective sweeteners, it could not completely omit the bitter taste and because of the limitation of using sweeteners, it was not possible to use extra sweeteners. In the F_{11 sample}, which most of the bitter taste was vanished, the sugar content in F₁₂ was lessened, but it was not affective. The attempt to replace half of sugar content by xylitol in F_{13 sample} was not successful. In F₁₄ and F₁₅ samples more contents of sugar were replaced by xylitol but the bitter taste was not omitted, the only merit was decreasing the sugar and increasing xylitol with more benefits. In F_{16 sample} maltitol was used in combination with sugar and aspartame and the bitter taste decreased. In F₁₇ sample, the amount of liquid glucose increased and glycerol decreased. Not only the taste of this sample was desirable, but also the organoleptic properties of that were appropriate. In order to investigate the effect of various sweeteners, the samples of F₁₈, F₁₉, F₂₀ and F₂₁ were prepared. All of them had acceptable tastes, but the F₁₇ sample had the most appropriate taste among the others.

As it is demonstrated in Figure 1, the drug release patterns of samples with various sweeteners (F₁₇, F₁₈, F₁₉, F₂₀ and F₂₁) are similar and the MDT values which are about 4.9, confirm this. At 5, 10, 15, 30 and 45 min after masticating, the drug release was 15, 40, 50, 76 and 96%, respectively. The slight difference may relate to different sweetener contents with alcoholic structures (maltitol and xylitol) in chewing gum formulation. Samples of F₁₇ and F₁₈ consist of 200 mg, F₂₀ and F₂₁ consist of 300 mg and F₁₉ consist of 600 mg of alcoholic sweeteners. The drug release of caffeine chewing gum at 10, 20 and 30 min reported by Aslani et al.[32] was 55, 78 and 89%, respectively. Another study by Tyrpin et al.[33] reported the drug release of caffeine coated chewing gum at 20 min of 88% and at 40 min of 97%. The variation in the measured values and the reported values may relate to different substances in green tea, which can affect the caffeine release. In another study by Aslani et al.[34] on nicotine chewing gum, although the employed gum bases were similar to the gum bases used in the current study, the drug release of majority of samples at 30 min were in the range of 79-83% of the affective substances. Kvist et al.[35] reported a complete release of nicotine from 2 mg nicotine chewing gum in about 45 min. Another study from Kvist et al.[36] on 20 mg dimenhydrinate chewing gum showed about 90% release of dimenhydrinate from the gum in about 45 min. The drug release from chewing gum is dependent on its water solubility, the more water-soluble substance is, the more release from chewing gums occurs and vice versa.[15]

Samples of F₂₂ and F₂₃ with various gum bases were prepared in order to compare the drug release pattern of these gum bases with the F₁₇ sample. As it is demonstrated in Figure 2, the drug release pattern of F₂₂ sample, which consists of softer gum bases (fruit C and stick), in the same time shows more caffeine release in comparison with F₁₇ and F₂₃, which consist of lower content of those soft gum bases. The MDT value of F₂₂ sample is less than F₁₇ and F₂₃ samples that means the release rate for this formulation is higher than others. The Figure 2 also illustrates that the F₂₃ sample, which consists of harder gum bases (elvasti and 487), in the same time exhibits less caffeine release in comparison with others and the MDT value of this formulation is higher, which intends slower release rate. Consequently, the samples with softer gum bases showed more release in the same times.

The drug release kinetics of the samples was calculated. The zero order release constant (K₀) for samples with various sweeteners of F₁₇, F₁₈, F₁₉, F₂₀ and F₂₁ were 1.554, 1.556, 1.615, 1.685 and 1.605 μg/(ml.min) with the r-squared values (R²) of 0.908, 0.902, 0.871, 0.877 and 0.874, respectively. On the other hand, the zero order release constant for samples with various gum bases of F₁₇, F₂₂ and F₂₃ were 1.554, 1.477 and 1.449 μg/(ml.min) with the r-squared values of 0.908, 0.732 and 0.935, respectively.

The first order release constant (K₁) for samples with various sweeteners of F₁₇, F₁₈, F₁₉, F₂₀ and F₂₁ were 0.008, 0.009, 0.019, 0.024 and 0.011 min^-1 with the (R²) values of 0.962, 0.951, 0.917, 0.925 and 0.959, respectively. While, the values of 0.008, 0.017 and 0.006 min^-1 were obtained for the samples with various gum bases of F₁₇, F₂₂ and F₂₃ with the r-squared values of 0.962, 0.967 and 0.961, respectively.

As all the r-squared values for the first order model were near one, the drug release kinetics of the gums is the first order.

The content uniformity results confirmed that the caffeine contents of various samples are near each other.

Organoleptic investigations showed that F₁₆, F₁₇, F₁₈, F₁₉, F₂₀, F₂₁, F₂₂ and F₂₃ samples have appropriate organoleptic properties among the others. The samples of F₁₇, F₁₈, F₁₉, F₂₀, F₂₁, F₂₂ and F₂₃ elected for taste evaluation. Cinnamon and peppermint were more preferable flavors among the other flavors. It is notable that eucalyptus taste affected the gum base and induced extra softening in chewing gum. Banana and cherry were not able to cover the bitter taste of green tea. Cinnamon has a sweet taste itself in comparison with other flavoring agents and the taste of chewing gum became more acceptable while using cinnamon. The use of aspartame is reported to cover the bitter taste of nicotine chewing gum as well as green tea, but with different flavoring agents of cherry and eucalyptus.[34]

As illustrated in Figure 3, the F₂₁, F₂₂ and F₂₃ samples demonstrated ductile behavior. As the constant strain rate was applied, the samples displayed linear elastic behavior, defined by a linear stress-strain relationship, in which deformations are completely recoverable upon removal of the load; that is, the specimens show elastic behavior at these elongations. As the tension increases, nonlinear behavior appears and deformations are plastic. It means that the plastically deformed specimens do not completely return to their original size and shapes when unloaded. More strain causes yielding followed by stress softening, in which the stress decreases with increasing strain. Elongating more tended the specimens to break. All three samples have similar Young modulus of around 0.7 MPa. The yield points of F₂₁, F₂₂ and F₂₃ samples occur at the stresses of 0.96, 0.76 and 1.28 MPa and strains of 5.46, 5.45 and 4.98%, respectively. The yield point for the F₂₃ sample with more elvasti and 487 bases take place at higher stresses, in contrast, for the F₂₂ sample with more fruit C and stick bases, lower yield point among the other samples happen. It is notable that the linear elastic portion of F₂₃ sample is more than the one for others and F₂₂ sample is lowest. According to these mechanical properties it can be predict that due to the same young modulus, all samples show similar stiffness while chewing. Furthermore, the F₂₃ sample may sustain its chewable manner as it has higher yielding and behaves more elastic as it has larger elastic range. The F₂₂ sample may lose its chewability due to lower yielding and behaves more plastic as it has lower elastic range. The F₂₁ sample has a medial behavior.

CONCLUSION

The extracted green tea contained 207.32, 130.00 and 200.82 mg/g of caffeine, catechin and flavonoid, respectively, depicts that the Iranian green tea used in this study includes an appropriate range of effective ingredients. The caffeine release of chewing gums with softer gum bases were more than the ones with harder gum bases at the same times. It was also observed that samples with the same gum bases, but with various formulations had similar caffeine release pattern and the drug release kinetics followed the first order model. Tensile analysis of three samples with different gum bases showed that the samples broke after yield point under tension. The prepared chewing gums had various organoleptic properties. The sample with equal content of gum bases had appropriate organoleptic properties. A combination of sugar, aspartame and maltitol covered the bitter taste of the green tea. The selected tastes by volunteers were cinnamon and peppermint, respectively.