Evaluating the use of cinnamon-water extract as taste modifier in yoghurt drink by temporal dominance of sensation

Development of low sugar food product has become a trend in food industries as the increase of diabetic prevalence. Cinnamon (Cinnamomum burmannii) has the potential to be used as a yoghurt drink taste modifier that expected to reduce sugar application. The goal of this study was to obtain the sensory attribute profile of cinnamon yoghurt drink with different concentrations of sugar and cinnamon, and evaluate the ability of cinnamon as sweet and sour taste modifier in yoghurt drink. This study involved 11 trained panelists to describe the sensory attribute profile of cinnamon yoghurt drink using the temporal dominance of sensations (TDS) method with 3 different concentrations of sugar (7,5%; 10%; and 12,5%) and cinnamon (0%; 5%; and 10%). It is important to note that the increase of cinnamon tended to suppress the sourness instead of enhancing the sweetness. Thus, it will lead to further sugar reduction application.


Introduction
In 2020, Indonesia was the sixth largest producer of yogurt in the world, with a production figure reaching 6,485 tons of yogurt, according to the Food and Agriculture Organization Statistical Database (FAOSTAT).There was an increase of approximately 20% compared to the production in 2013, which was only 5,320 tons.The yogurt industry in Indonesia has experienced growth due to improvements in taste and texture of commercially sold yogurt.Previously, yogurt was available in a thick-textured and plain (sour) flavor, but now there are yogurt drinks with a more liquid consistency, making them easier to consume directly from the packaging, and they come in various flavor variations [1].Based on this explanation, yogurt drink was chosen as the subject of research in this study.
According to Wantesan et al. [2], consumers in Indonesia have a higher preference for yogurt drinks with a sweet taste and aroma.This is supported by data from the 2018 National Basic Health Research Report from the Republic of Indonesia's Ministry of Health, which states that 61.27% of the Indonesian population has a habit of consuming sweet beverages at least once a day.Commercially sold yogurt drinks in Indonesia typically use flavors from fruit extracts, fruit pulp, or other fruit parts.However, cinnamon (Cinnamomum burmannii) also has the potential to be used as a flavor for yogurt drinks.
According to Omoarukhe et al. [3], cinnamon can be used to enhance sweetness in foods or beverages containing sugar.However, according to Rao and Gan [4], the compound cinnamaldehyde found in cinnamon can actually reduce sweetness and acidity.There is no research yet that discusses the effect of adding cinnamon on changes in sweetness and acidity, so the researchers want to prove its validity.According to Gutierrez et al. [5], cinnamon extract added to yogurt still contains 34.7% total phenolic 1302 (2024) 012098 IOP Publishing doi:10.1088/1755-1315/1302/1/012098 2 compounds, so the infusion extraction method was chosen for this research.The infusion extraction method is performed using water as a solvent at temperatures of 40-60°C for 15-20 minutes.
To understand consumer perceptions and preferences, the sensory attribute profile of cinnamon yogurt drink must be evaluated.One common method for profiling sensory attributes is quantitative descriptive analysis (QDA).However, because perception of taste is dynamic and greatly influenced by processes that occur in the mouth, a more appropriate method for describing the sensory attribute profile of cinnamon yogurt drink is temporal dominance of sensations (TDS).With the TDS method, changes in sensory attribute intensity can be assessed based on the time spent in the mouth, allowing panelists to compare several sensory attributes perceived simultaneously, especially for samples with complex sensory characteristics like yogurt [6].In the TDS method, sensory attributes in the sample are identified based on the concept of dominance.A sensory attribute is considered dominant if it can attract the panelists' attention, even if it may not be the most intense attribute [7].The TDS method has been used by Chadha et al. [8] to analyze the descriptive profile of single and mixed sweeteners for the development of sweetener products.

Research observation
This research uses a Completely Randomized Block Design (CRBD) with two factors: the concentration of added sugar and the concentration of added cinnamon extract.Factor I (sugar) had three treatment levels of added sugar concentration (G): 7.5%, 10%, and 12.5%.Factor II (cinnamon) has three treatment levels of added cinnamon extract concentration (K): 0%, 5%, and 10%.

Making of the cinnamon yoghurt drink samples
Cinnamon yogurt drink samples were made by adding cinnamon water extract to the yogurt drink starter culture.To make the yogurt drink starter, 30 grams of NZMP brand skim milk powder was weighed and dissolved in 250 ml of 80°C mineral water in a glass jar.The dissolved and homogenized skim milk was then cooled to 37°C.Once it reached 37°C, the dissolved skim milk was mixed with 0.25 grams of Lactina brand starter powder and incubated at 37°C for 12 hours.To create the cinnamon water extract, cinnamon sticks were broken into 3-5 cm pieces and placed in a french press.Then, 200 ml of 65°C mineral water was added to the french press, and the mixture was allowed to steep for 10 minutes to enable the extraction process using the infusion method.After 10 minutes, the cinnamon water extract was transferred to a brown bottle and stored in the refrigerator.To make the cinnamon yogurt drink sample, 10 ml of the yogurt drink starter culture was added to 200 ml of 37°C skim milk that had been previously sweetened according to the treatment.The milk, which had been added with the starter culture, was then incubated at 37°C for 6 hours.After the 6-hour incubation period, the skim milk had turned into yogurt drink, and it was then mixed with the cinnamon water extract according to the treatment.

Sensory evaluation by temporal dominance of sensations (TDS)
There are three stages in the TDS test, consisting of panelist selection, panelist training, and testing stages.Before the panelist selection stage begins, recruitment and interviews were conducted to identify potential panelists.After obtaining the potential panelists, the panelist selection stage was continued using a triangle test method to assess their ability to recognize basic sweet and sour tastes.After the panelist selection stage, 11 panelists were selected to proceed to the training stage.During the training stage, the panelists were introduced to the TDS method and familiarized with the use of the SensoMaker software version 1.8.This research investigated 5 sensory attributes, included sweet taste, salty taste, sour taste, bitter taste, and cinnamon flavor.The sequence of dynamic sensory perception was evaluated for each sample and the changes of DR_max values were then further analysed by General Linear Model on Minitab 19.

Total sugar
The total sugar test was conducted quantitatively using the anthrone-sulfate method.The cinnamon yogurt drink samples were homogenized with calcium carbonate (CaCO3) and distilled water while being heated to boil.After cooling, 5 ml of the sample was mixed with distilled water, Pb-acetate, and Na-oxalate.The sample was then homogenized and filtered using filter paper.The filtrate was the rediluted with distilled water.For the total sugar testing, 1 ml of the diluted filtrate with a concentration of 0.2 mg/ml was taken and mixed with 5 ml of the anthrone reagent.The sample solution and anthrone reagent, once homogenized, were then heated on a waterbath for 12 minutes at a temperature of 100°C.After cooling, the solution's absorbance was measured by a spectrophotometer at its maximum wavelength (630 nm).Each sample was replicated three times.

Total titrable acidity (TTA)
The TTA value method measures the content of organic acid compounds equivalent to lactic acid.The cinnamon yogurt drink samples were titrated with 0.1 N sodium hydroxide (NaOH) solution until a constant pink color was observed.Each sample was repeated three times.

Sensory profile of cinnamon yoghurt drink
The nine samples of cinnamon yogurt drink, represented by the codes G7K0, G7K5, G7K10, G10K0, G10K5, G10K10, G12K0, G12K5, and G12K10, were described based on the most dominant sensory attributes.The correlation of sensory attribute dominance rate for each sample of cinnamon yogurt drink, according to the panelists' evaluations, can be seen in Figure 1a.In the Principal Component Analysis (PCA) figure, the distribution and correlation of sensory attributes of cinnamon yogurt drink samples are represented as dots.Positive relationships occur when the positions of the dots are close to each other and form angles below 90 degrees from the center point or are in the same quadrant.On the other hand, negative relationships occur when the positions of the dots are far apart and form angles above 90 degrees from the center point or are in different quadrants [9].The PCA graph in Figure 1a consists of variables and treatments.The variables include the dominance rate values of the sweet, sour, and cinnamon sensory attributes, while the treatments consist of the nine yogurt drink samples used in this research.The component of variables and treatments accounts for 91.93% of the sample's variability, obtained by summing up the percentages of PC1 and PC2.
Based on Figure 1a, when the dominance rate of one taste increases, the dominance rates of other tastes decrease.The dominance rate of sweetness is perceived to increase when the dominance rates of cinnamon and sour tastes decrease.The same applies to the dominance rates of sour and cinnamon tastes.However, changes in the dominance rates of salty and bitter tastes do not affect the panelists' perception of the dominance rates of sweetness, cinnamon, and sour tastes because the positions of these dots are very close to the center of the graph, making it difficult to be explained well by the factors that constitute the biplot [9].

TDS evaluation
3.2.1.Addition of 7.5% sugar concentration.The addition of cinnamon to the yogurt drink samples with 7.5% sugar concentration overall reduces the dominance rate of sweetness and sourness, while increasing the dominance rate of cinnamon flavor.The decrease in the dominance rate of sweetness and sourness is indicated by the decreased DR_max values of sweetness and sourness, whereas the increase in the dominance rate of cinnamon flavor is indicated by the increased DR_max value of cinnamon flavor.The decrease in the DR_max value of sourness is greater compared to the decrease in the DR_max value of sweetness (Figure 1b).The DR_max value of sweetness in the yogurt drink samples significantly differs with a p-value of 0.000 (<0.05) after being tested using ANOVA.From the results of the ANOVA test, it can be concluded that the addition of different cinnamon concentrations has a significant effect (α = 0.05) on the DR_max value of sweetness.The larger the addition of cinnamon, the smaller the DR_max value of sweetness becomes.

Addition of 10% sugar concentration.
The addition of cinnamon to the yogurt drink samples with 10% sugar concentration overall reduces the dominance rate of sweetness and sourness, while increasing the dominance rate of cinnamon flavor.The decrease in the dominance rate of sweetness and sourness is indicated by the decreased DR_max values of sweetness and sourness, whereas the increase in the dominance rate of cinnamon flavor is indicated by the increased DR_max value of cinnamon flavor.The decrease in the DR_max value of sourness is greater compared to the decrease in the DR_max value of sweetness (Figure 1b).
The DR_max value of sweetness in the yogurt drink samples significantly differs with a p-value of 0.000 (<0.05) after being tested using ANOVA for the treatment of different cinnamon concentration additions.From the results of the ANOVA test, it can be concluded that the addition of different cinnamon concentrations has a significant effect (α = 0.05) on the DR_max value of sweetness.The larger the addition of cinnamon, the smaller the DR_max value of sweetness becomes.

Addition of 12.5% sugar concentration.
The addition of cinnamon to the yogurt drink samples with 12.5% sugar concentration overall reduces the dominance rate of sweetness and sourness, while increasing the dominance rate of cinnamon flavor.The decrease in the dominance rate of sweetness and sourness is indicated by the decreased DR_max values of sweetness and sourness, whereas the increase in the dominance rate of cinnamon flavor is indicated by the increased DR_max value of cinnamon flavor.The decrease in the DR_max value of sourness is greater compared to the decrease in the DR_max value of sweetness (Figure 1b).
The DR_max value of sweetness in the yogurt drink samples significantly differs with a p-value of 0.000 (<0.05) after being tested using ANOVA for the treatment of different cinnamon concentration additions.From the results of the ANOVA test, it can be concluded that the addition of different cinnamon concentrations has a significant effect (α = 0.05) on the DR_max value of sweetness.The larger the addition of cinnamon, the smaller the DR_max value of sweetness becomes.

The potential of cinnamon-boiled water as taste modifier based on TDS evaluation.
Based on the TDS evaluation results, it is known that the addition of cinnamon decreases the dominance rate of sweetness and sourness in yogurt drink with sugar concentrations of 7.5%; 10%; and 12.5%.This result contradicts the statement by Nuffer et al. [10], but aligns with the statement by Aeran et al. [11].According to Nuffer et al. [10], cinnamon can enhance the sweetness in food or beverages containing sugar.However, after tasting the cinnamon-boiled water extract, it does not have a sweet taste, suggesting that cinnamon's ability to enhance sweetness in food or beverages with sugar may come from its sweet aroma.According to Ullah et al. [12], the taste of a food or beverage can be elicited through its aroma, as the tongue can perceive flavors according to the provided aroma.
According to Aeran et al. [11], the compound cinnamaldehyde found in cinnamon can decrease the perception of sweetness and sourness.Cinnamaldehyde is a Transient Receptor Potential Cation Channel, subfamily A, member 1 (TRPA1) receptor in trigeminal nerves.According to Rhyu et al. [13], TRPA1 channels are activated by acidic stimuli and play a role as inhibitors against sour taste stimuli in sour taste receptor cells in the mouth.In flavor perception, there are three sensory systems involved: gustatory (taste), olfactory (aroma), and somatosensory (temperature, pain, touch, and muscle movement).These three sensory systems are connected to one another, so changes in one sensory system can affect the overall flavor perception.

Total sugar
The addition of cinnamon to yogurt drink samples with sugar concentrations of 7.5%; 10%; and 12.5% overall increases the total sugar content shown in Table 1.The total sugar in cinnamon yogurt drink samples comes from lactose in milk as well as the addition of granulated sugar (sucrose) and cinnamon.The factors of sugar concentration, cinnamon concentration, and different combinations of sugar and cinnamon concentrations significantly influence the total sugar content of cinnamon yogurt drink samples, with a p-value of 0.000 (<0.05).Samples with higher sugar and cinnamon additions have higher total sugar content as well.Streptococcus thermophilus and Lactobacillus bulgaricus can choose which sugar to preferentially use as their main source of energy among lactose, glucose, and sucrose [14].If lactose is selected as the primary energy source, it enters the cell through the lactose permease membrane protein and is converted into lactose-6-phosphate by phosphoenolpyruvate (PEP) first.Lactose-6-phosphate is then hydrolyzed into glucose and galactose by the enzyme β-phosphogalactosidase.Through the glycolysis process of the Embden-Mayerhoff Parnass (EMP) pathway, glucose is converted into pyruvic acid, which is then broken down into lactic acid and energy (ATP) by the lactate dehydrogenase enzyme [15].
Meanwhile, galactose will be expelled from the cell into the medium (yogurt) because Streptococcus thermophilus and Lactobacillus bulgaricus have a low capacity for fermenting galactose, thus galactose cannot be maximally utilized as an energy source [14].According to Gasser et al. [16], Streptococcus thermophilus actually possesses the gene to convert galactose into glucose via the Leloir pathway.However, there is a mutation in the galactokinase gene (galK) promoter that limits the ability of Streptococcus thermophilus to use the Leloir pathway.The limitation of Streptococcus thermophilus in utilizing galactose is the result of evolution, as the expulsion of galactose from the cell allows lactose to enter through an antiporter mechanism in the lactose permease to reducing sugar.
Streptococcus thermophilus and Lactobacillus bulgaricus can also use sucrose as a source of energy.Sucrose that enters the bacterial cell will be hydrolyzed into glucose-6-phosphate and fructose by the enzyme ScrB hydrolase (β-fructofuranosidase or sucrose-6-phosphate hydrolase).Glucose-6-phosphate will be converted into pyruvic acid and lactic acid through the glycolysis process of the Embden-Mayerhoff Parnass (EMP) pathway.Meanwhile, fructose will be expelled from the cell into the medium (yogurt).The re-entry of fructose into the medium (yogurt) will increase the total sugar content as it is a reducing sugar [17].
The addition of cinnamon to the yogurt drink also increases its total sugar content.According to Putri and Fibrianto [18], cinnamon extracted at a temperature of 60°C contains reducing sugars produced from its essential oil.However, the increase in total sugar in the yogurt drink does not increase its sweetness dominance; in fact, it decreases.According to Aeran et al. [11], the compound cinnamaldehyde found in cinnamon can reduce the intensity of sweetness in food or beverages, requiring a larger amount of sugar to be perceived as sweet.That's why the increase in total sugar in the cinnamon yogurt drink does not enhance its sweetness dominance, as a larger amount of sugar is needed to counteract the antagonistic effect of cinnamon.

Total titrable acidity
The addition of cinnamon to the yogurt drink samples with concentrations of 7.5%; 10%; and 12.5% sugar overall decreases its total acidity shown in Table 2.Only the factors of sugar and cinnamon concentration have a significant effect on the total acidity of the cinnamon yogurt drink samples, with a p-value of 0.000 (<0.05).The combination of sugar and cinnamon has a p-value of 0.869 (>0.05), indicating that it does not have a significant effect on the total acidity of the cinnamon yogurt drink samples.Both sugar and cinnamon have a negative effect on the total acidity of the cinnamon yogurt drink.The higher the sugar concentration added, the lower the total acidity.Lactic acid bacteria (LAB) utilize carbohydrates as their source of energy through the process of fermentation.There are two types of fermentation pathways by lactic acid bacteria (LAB), namely homofermentative and heterofermentative.The homofermentative pathway produces lactic acid as a result of fermentation, while the heterofermentative pathway produces lactic acid and acetic acid as the fermentation products [19].According to SNI 2981:2009, yogurt is considered to meet the quality criteria if it has a total acidity of 0.5-2.0%.The total acidity of cinnamon yogurt drink ranges from 0.82-1.03%,thus still meeting the quality requirements of SNI 2981:2009 for the acidity test.The production of cinnamon yogurt drink is carried out using the commercial starter culture brand Lactina, which consists of Streptococcus thermophilus and Lactobacillus bulgaricus, which is ferment lactose homofetmentatively using the enzyme lactic dehydrogenase (LDH), resulting in the production of lactic acid during the lactose catabolism process by Streptococcus thermophilus and Lactobacillus bulgaricus [19].Lactic acid plays a role in providing sharp and refreshing taste, as well as forming a slightly thick texture in yogurt [20].Streptococcus thermophilus generally produces L(+) lactic acid, while Lactobacillus bulgaricus generally produces D(-) lactic acid.During the yogurt-making process, Streptococcus thermophilus grows faster than Lactobacillus bulgaricus, resulting in the production of L (+) lactic acid before D (-) lactic acid.Sugar has a negative effect on the total acidity of yogurt drink because higher concentrations of added sugar will lead to a decrease in the activity of lactic acid bacteria (LAB) in the yogurt drink [21].

Conclusions
From the TDS test results, it is known that the addition of cinnamon reduces the dominance rate of sweetness and acidity in yogurt drink with 7.5%, 10%, and 12.5% sugar concentrations.The decrease in the DR_max value for acidity is greater than the decrease in the DR_max value for sweetness, suggesting that the addition of cinnamon indirectly enhances the dominance of sweetness by masking the acidity.Regarding the total sugar content, the addition of cinnamon to the yogurt drink samples with 7.5%, 10%, and 12.5% sugar concentrations tended to increase the total sugar (p-value<0.05).Both sugar and cinnamon have a negative effect on the total acidity of the cinnamon yogurt drink (p-value<0.05).

Figure 1 .
Figure 1.Biplot PCA of sensory attributes of cinnamon yogurt drink samples based on dominance rate (a) and typical changes of DRmax (b)

Table 1 .
Total sugar value of cinnamon yoghurt drink samples The data obtained comes from the average of 3 replications.Different letter notations indicates significantly different values (α = 0.05)

Table 2 .
Total acid value of cinnamon yoghurt drink samples