Anthocyanin Degradation and Colour Kinetics of Cornelian Cherry Concentrate

Aims: The purpose of present study is to analyze the physicochemical properties (pH, total acidity, total monomeric anthocyanin, total phenolics and, total antioxidant activity) and to investigate thermal degradation kinetics of anthocyanins and Hunter colour parameters of cornelian cherry 60, and 80°C. Methods: Monomeric anthocyanin degradation fitted to a first order reaction kinetics. Hunter L* , a* , b* values were measured to characterize colour; total colour difference ( TCD *), lightness ( L * ), chroma ( C* ), and hue angle ( h*° ) were calculated from those values and, fitted to zero-order, ﬁrst-order and combined kinetics model. Results: half-life anthocyanin and cornelian cherry 60, 70 80°C, Temperature dependence of anthocyanin degradation rate constants was expressed as activation energy, E a , and E a was calculated kj/mol between 60-80°C. TCD *, L* , C* , and h*° best fits with combined kinetics model.


INTRODUCTION
Cornelian cherry (Cornus mas L.) fruits are widely grown in different regions of Turkey, especially in eastern and northern Anatolia. Cornelian cherries are typically olive shaped, single-seeded fruits, 10-20 mm long. They are typically red. The fruits have a sweet-sour taste. They contain high amount of vitamin C and are rich in sugar, anthocyanins, organic acids and tannins [1]. In Turkey, approximately 12,800 tons of cornelian cherry fruit is produced per annum. The fruit is either consumed directly or processed into various products such as jam, marmalade, pestil (a dried form of marmalade produced in the eastern part of Turkey), paste, and sherbet or is dried. Cornelian cherry fruits have also been used for the medical treatment of gastrointestinal disorder and diarrhea in Turkey [2].
Fruits and vegetables are a good source of natural antioxidants, containing many different antioxidant components which provide protection against harmful-free radicals and have associated with lower incidence and mortality rates of cancer and heart diseases in addition to a number of other health benefits [3]. Anthocyanins are a group of naturally occurring phenolic compounds, which are responsible for the attractive colours of many flowers, fruits (particularly in berries), vegetables and related products derived from them [4]. Anthocyanins are becoming increasingly important as antioxidants and are related to a broad range of beneficial effects in human health and disease prevention. Recently, some studies have been published on the physical and chemical properties of cornelian cherry fruits and also their antioxidant capacity, total phenolics and anthocyanin content [5][6][7]. Thermal processing is one of the most widely used methods of preserving and extending the useful shelf life of foods [8]. It is the one of the most important factors that affects the stability of anthocyanins.
Colour is an important organoleptic property in determining product quality, therefore minimizing the pigment losses during processing is of primary concern to the processor [9]. However, no information is available on the thermal degradation kinetics of cornelian cherry anthocyanins and colour values. Determination of the kinetic parameters is essential to predict the quality changes that occur during thermal processing. Therefore, the objectives of this study were (1) to determine the physicochemical properties of cornelian cherry fruit concentrate; (2) to investigate the thermal degradation kinetics of anthocyanins and Hunter colour parameters in prepared concentrates.

Chemicals
Pectolytic enzyme, Panzym XXL, was kindly gifted by Sinerji A.Ş., Mersin, TURKEY. Folin-Ciocalteu reagent was purchased from Sigma Chemical Co. All the other reagents were of analytical grade and purchased from Sigma Chemical Co.

Plant Material
In this study, naturally grown cornelian cherry variety in Karıngit village of Elazığ, Eastern Anatolia, Turkey, was used. Fully ripe Cornus mas L. fruits were collected at optimum growth in September. No supplemental fertilizer was applied to the fruit supplied trees.

Preparation of Cornelian Cherry Juice and Concentrate
All the foreign materials such as pieces of branches and leaves and also unripe and damaged fruits were removed from fruit samples by hand. The cleaned fruits were washed under cold tap water, stalks and seeds were removed. Fruits were ground by using a laboratory blender. Juice was immediately filtered through muslin to remove pulp from the juice. Then the juice was depectinized with 1.0% (v/w) Panzym XXL at 50°C for 2 h. The depectinized juice was allowed to rest at 4°C for 24 h. The juice was again filtered through five layer muslin and finally double layer filter paper to obtain a clear juice.

pH and Soluble Solids (TSS) Content
The pH and soluble solids content of the juice were measured immediately after concentration process using a pH meter (Nel-890 Model, Ankara, Turkey) and a digital refractometer (PTR 46X, England) at 20°C, respectively. The refractometer was calibrated using distilled water. The soluble solids content was expressed as °Brix. All measurements were done in triplicate and the average results reported.

Titratable Acidity
The titratable acidity of the concentrates was measured using a pH meter, where the juice was titrated against 0.1 N NaOH until the pH reached 8.2. The acidity was expressed as percentage of citric acid [10].

Determination of Total Phenolics
The total phenolic content was determined by the Folin-Ciocalteu method [11]. 100 μL of sample (diluted 1:5 (v:v) with methanol) was mixed with 6 ml of twice distilled water and 500 μL of Folin-Ciocalteu reagent was added. After waiting 5 minutes at room temperature, 1.5 mL of sodium carbonate (20% w/v) was added to adjust optimum pH for the reaction. The mixture was vortexed and incubated at room temperature (~23°C) for 2 h and absorbance was measured at 765 nm using a UV-VIS Lambda 25 spectrophotometer (Perkin Elmer, Shelton, USA). Gallic acid was used as a standard and, the content of total phenolics was expressed in mg gallic acid equivalents (GAE) per liter of concentrate. A mixture of water and reagents was used as a blank. All analyses were done in triplicate (n = 3).

Determination of Total Monomeric Anthocyanins
Total monomeric anthocyanin content was determined by pH-differential method described by Giusti and Wrolstad [12], using two buffer systems: potassium chloride buffer, pH 1.0 (0.025 M), and sodium acetate buffer, pH 4.5 (0.4 M). The concentrate samples were diluted in a ratio of 1:10 with twice distilled water. A 0.4 ml of diluted sample was mixed with 3.6 ml of corresponding buffers and allowed to equilibrate for 15 minutes at room temperature. The absorbance of each solution was measured at 510 nm (λ max ) and 700 nm, using UV-VIS Lambda 25 spectrophotometer (Perkin Elmer, Shelton, USA). Total monomeric anthocyanins were calculated as mg cyanidin-3-glucoside per liter concentrate according to the following equation: Total monomeric anthocyanins (mg/L) = A x MW x DF x 1000 / (ε x l) where A = (A 510 -A 700 ) pH 1.0 -(A 510 -A 700 ) pH 4.5 ; MW (molecular weight) = 449.2 g/mol for cyanidin-3-glucoside; DF = dilution factor (10) as final volume per initial volume; 1 = path length in cm; ε = 26,900 molar extinction coefficient in L/mol/cm for cyanidin-3-glucoside; 1000 = conversion factor from g to mg. Absorbance readings were made against twice distilled water as blank. DPPH in methanol. The mixture was vortexed and left to stand for 30 min in dark place at room temperature. Then the absorbance was measured at 515 nm using UV-VIS Lambda 25 spectrophotometer (Perkin Elmer, Shelton, USA). The percent of reduction of DPPH was calculated by the formula reported by Tural and Koca [2]: (2) where A C = absorbance of a control (t = 0 min), A S = absorbance of a tested sample at the end of the reaction (t = 30 min). Methanol was used as blank and control sample was prepared with the same volume of methanol mixed with DPPH stock solution. All assays were done in triplicate (n = 3).

Degradation Studies
Thermal degradation of cornelian cherry concentrate was studied in 43.52 °Brix concentrate at 60, 70 and 80°C. Aliquots of 10 mL of samples were put into screw-cap test tubes to prevent evaporation and test tubes were placed into oven preheated to a given temperature. At regular time intervals (0, 2, 4, 6, 8, and 10 h), samples were removed from the oven (NÜVE EN500, Ankara, Turkey) and rapidly cooled by plunging into an ice bath to stop further degradation. Contents of total anthocyanins and colour values of the samples were measured immediately.

Degradation Kinetics of Anthocyanins
Previous studies showed that thermal degradation of anthocyanins followed a firstorder reaction [4,[14][15][16]. This kinetic type was expressed by the following equation: where C o is the initial anthocyanin contents and C is the anthocyanin contents after time t (min) of heating at the given temperature while k 1 is the first order rate constant. The parameters of first order kinetic model (Eq. (3)) were estimated (Sigma Plot 10.0 Windows version, SPSS Inc.).
Half-lifes (t 1/2 ) which is the time needed for 50% degradation was calculated by the following equation: where t 1/2 is the half-lifes and, k 1 is the first order degradation rate constant (h -1 ).
The effect of temperature on the degradation rate constants was expressed by the linearized Arrhenius equation by plotting ln k against 1/T in which the temperature dependence of k was quantified by the activation energy E a according to Eq. (5).
where k is the rate constant (min ), E a is the activation energy (kJ/mol), R is the universal gas constant (8.314 J/mol/ K), T is the absolute temperature (Kelvin, K). The E a value was calculated from the slope of the straight lines given by Eq. (5), using Sigma Plot (Sigma Plot 10.0 Windows version, SPSS Inc.).

Kinetics Model of Visual Colour
The complexity of fruit juices and derivatives implies a wide range of enzymatic and nonenzymatic browning reactions caused by thermal treatments. Consequently it is difficult to establish a reaction mechanism and to obtain a kinetic model describing the global process adequately [17]. There are numerous references on the kinetics of colour of food materials in the literature. The majority of these works report zero-order (Eq. (6)) or first-order (Eq. (3)) degradation reaction kinetics.
= ± * (6) Sometimes the relatively simple models described do not adequately represent colour change mechanism. That is why a combined kinetics has been developed, in which the nonenzymatic colour change reactions are considered to consist of two stages. A first stage of coloured polymeric compound formation following zero order kinetics, second stage supposes decomposition of coloured polymers into non-coloured compounds following a first order kinetics. According to this combined kinetics, the colour change mechanism can be expressed by [17,18]: The terms C and C 0 are the concentrations of colour parameters at any time t and initial concentration, respectively; k 0 is the zero-order kinetics constant, k 1 is the first-order kinetics constant in Eqs.
where, * (0.98), * (4.17) and * (0.78) refer to initial values, and L * , a * and b * refer to colour values at various times during heat treatment.

Statistical Analysis
Experimental data were subjected to two way ANOVA and the means were compared by Duncan's multiple range test at P < 0.05 significance level using SPSS version 17 (SPSS Inc., Chicago, IL, USA). The parameters of kinetic models and Arrhenius equation were estimated by either linear regression procedure or non-linear regression iterative procedure (Sigma Plot 10.0 Windows version, SPSS Inc.). Total monomeric anthocyanin, total phenolic matter and total antioxidant activity of cornelian cherry concentrate determined as 207 mg/L, 0.0218 GAE/L and, 96% inhibition, respectively. As compared to the studies of Tural and Koca [2] on physico-chemical and antioxidant properties of cornelian cherry fruits grown in Turkey, content of total phenolics was relevant with their studies but, total monomeric anthocyanin content and total antioxidant activity values were higher than their findings.

Degradation Kinetics of Total Monomeric Anthocyanins
Degradation of anthocyanins during heating was plotted as a function of time (Fig. 1). Decrease in anthocyanin content was 63.77%, 71.50% and 89.37% for heating at 60, 70, 80°C, respectively, at the end of 600 min. It is clear from Fig. 1 that the thermal degradation of cornelian cherry anthocyanins followed first order reaction kinetics with respect to temperature. The extent of anthocyanin degradation was significantly higher (P < 0.05) ( Table 2) at higher temperatures [22] and, degradation showed faster decreasing trend for the first two hours and rather slower decreasing trend during the course of treatment time (Fig. 1). That is, as anthocyanin concentration decreased the degradation rate also decreased. These results show that the rate of the degradation is directly proportional to the concentration of pigment, agree with those of previous studies [4,[14][15][16]23,24]. The kinetic parameters of anthocyanin degradation during heating were given in Table  3. The k 1 values for anthocyanin degradation were 0.002, 0.027 and 0.054 min -1 in cornelian  (Table 3) and the degradation rate was dependent on temperature, being faster at high temperatures. It can be concluded that anthocyanin degradation was greatly dependent on temperature as indicated by higher at higher temperatures [22].
Since no kinetic data have been found in the literature on the thermal degradation of cornelian cherry anthocyanins, we compared the thermal stability of cornelian cherry anthocyanins with other anthocyanin sources. 6 70 and 80°C, respectively. As temperature increased k 1 values increased (Table 3) and the degradation rate was dependent on temperature, being faster at high temperatures. It can be concluded that anthocyanin degradation was greatly dependent re as indicated by higher k 1 values Since no kinetic data have been found in the literature on the thermal degradation of cornelian cherry anthocyanins, we compared the thermal stability of cornelian cherry anthocyanins with ther anthocyanin sources. To determine the effect of temperature on the parameters studied, the constants obtained from Eq. (3) were fitted to Arrhenius equation Eq. (5) at 60, 70 and 80°C (Fig. 2). The calculated activation energy E a was 48.38 kj/mol (Table 3). This value is lower when compared t other studies [4,22,23]. A low activation energy signified a higher rate of reaction for anthocyanins whereas a higher activation energy indicated a retarded rate of degradation [26]. These results were consistent with since cornelian cherry had the least each case. The difference in activation energy values could be due to different soluble solid contents [23] and compositional change in samples being treated [16].

Fig. 1. Degradation of anthocyanins in cornelian cherry concentrates during heati at 60, 70 and 80°C
; Article no. BJAST.19193 susceptible to high temperatures. These results clearly indicate that anthocyanins from cornelian cherry concentrate are the least heat-stable, hose from blackberry juice and sour cherry concentrate. In literature different anthocyanin composition was also reported for [1,3]. Cornelian cherry has different anthocyanin composition than blackberry [4], sour cherry [4], and blood carrot [15] anthocyanin. In this respect as reported by Wang and Xu [4] and Yang et al. [25] different susceptibilities of fruit juice anthocyanins to heat might be due to their varying anthocyanidin To determine the effect of temperature on the meters studied, the constants obtained from Eq. (3) were fitted to Arrhenius equation Eq. (5) at 60, 70 and 80°C (Fig. 2). The calculated was 48.38 kj/mol (Table 3). This value is lower when compared the results of A low activation energy signified a higher rate of reaction for anthocyanins whereas a higher activation energy indicated a retarded rate of degradation [26]. These results were consistent with t 1/2 values since cornelian cherry had the least t 1/2 values at each case. The difference in activation energy values could be due to different soluble solid contents [23] and compositional change in

Change in Visual Colour
Colour of cornelian cherry concentrate during the thermal treatment was characterized in terms of L * , a * and b * values. It was observed that b*and L * values decreased during heat processes at 60, 70, 80°C (Fig. 3). Decrease in a* value was 57.5%, 61.6% and 71.0% for heating at 60, 70, 80°C, respectively. Decrease in b * value was 29.4%, 39.4% and 45.4% for heating at 60, 70, 80°C, respectively. Decrease in b * value during heating process was reported by other authors in pineapple puree [27] double concentrated tomato paste [28]. Decrease in L * value was 26.5%, 30.6% and 35.3% for heating at 60, 70, 80°C, respectively. The L* value decreased significantly ( with time and treatment temperature. R in b* and L* were not very severe as compared to a * value. Decrease in L* during heating process was found by other authors [27,

Fig. 2. The Arrhenius plot for degradation of anthocyanins in cornelian cherry concentrate during heating
Colour of cornelian cherry concentrate during the thermal treatment was characterized in terms of values. It was observed that a * , values decreased during heating processes at 60, 70, 80°C (Fig. 3). Decrease in value was 57.5%, 61.6% and 71.0% for heating at 60, 70, 80°C, respectively. Decrease value was 29.4%, 39.4% and 45.4% for heating at 60, 70, 80°C, respectively. Decrease ng process was reported by other authors in pineapple puree [27] and, double concentrated tomato paste [28].
value decreased significantly (P < 0.05) me and treatment temperature. Reduction were not very severe as compared during heating was found by other authors [27,28].
Decrease of Hunter L* and a* expressed due to fading of the red colour destroyed anthocyanin pigments which are unstable in fruit juices and polymerization of anthocyanins with other phenolics [29].

Degradation Kinetics of Visual Colour
Total colour difference (TCD*), lightness ( chroma (C*), and hue angle (h* were used and modeled since the most common L * a * b * coordinates do not express hue and chroma directly and difficult independently [19,30]. Therefore, h*° parameters were calculated by using values (Eqs. (8)-(10)) and experimental data for change in parameters L * , C*, h*°and fitted to zero-order (Eq. (6)), firstand combined kinetic model (Eq. (7)) and the best fit was selected as model due to the highest determination coefficients.

Degradation Kinetics of Visual Colour
, h*°) parameters were used and modeled since the most common coordinates do not express hue and chroma directly and difficult to interpret TCD*, C* and parameters were calculated by using L * , a * , b * experimental data for and TCD* were -order (Eq. (3)) and combined kinetic model (Eq. (7)) and the best fit was selected as model due to the highest

Fig. 3. Variation of lightness (
Since L* is a measure of colour on the light axis, decrease in L* value indicates that the samples were turning darker. In this s combined kinetic described the experimental data of L* better than zero and first order kinetics models due to having highest determination coefficients (R 2 ) ( Table 4). Variation of cornelian cherry concentrate fitted to combined model during heating at 60, 70 and 80°C is given in Fig. 3. In each temperature, k found higher than k 1 , that is the rate of colour formation based upon Maillard reactions is higher than the rate of colour destruction based upon pigment destruction for L* value (Table 4). It was reported that when the ratio of kinetic constants k o (colour appearance) and destruction) is greater than unity, Maillard reaction predominates over pigment destruction [31]. In this respect, decrease in L* treatment at 60, 70, 80°C gave the best fit with combined kinetic model and, predominantly caused by Maillard reaction resulting in darkening of colour and this darkening will fasten as temperature increased. In literature, change in lightness has been fitted first order kinetics for pineapple puree [27]; apple pulp, peach pulp and plum pulp [32]; pear puree [17] and peach puree [18]. However, Barreiro et al. [28] reported that most of the quality-related reaction rates are either zero or first order reactions and the statistical difference between the two types may be small. Similar result was reported by Lozano and Ibarz [32]. is a measure of colour on the light-dark value indicates that the samples were turning darker. In this study, the combined kinetic described the experimental better than zero and first order kinetics models due to having highest determination ) ( Table 4). Variation of L * value of cornelian cherry concentrate fitted to combined l during heating at 60, 70 and 80°C is given k o values was , that is the rate of colour formation based upon Maillard reactions is higher than the rate of colour destruction based upon value (Table 4). It was reported that when the ratio of kinetic constants (colour appearance) and k 1 (pigment destruction) is greater than unity, Maillard reaction predominates over pigment destruction L* due to heat treatment at 60, 70, 80°C gave the best fit with combined kinetic model and, predominantly caused by Maillard reaction resulting in darkening of colour and this darkening will fasten literature, change in een fitted first order kinetics for ; apple pulp, peach pulp and and peach puree [28] have been related reaction irst order reactions and the statistical difference between the two types may be small. Similar result was reported The chroma (C*) is a measure of chromaticity, which denotes the purity or saturation of the colour [33]. C* was calculated from Eq (9). Fig. 4 represents the variation of C* value of cornelian cherry concentrate during heating at 60, 70 and 80°C. Decrease in C* value was 55.4%, 59.9% and 68.1% for heating at 60, 70, 80°C, respectively.
The C* value decreased significantly (P < 0.05) ( Table 2) with time and treatment temperature. That is, stability of red colour of cornelian cherry concentrate decreased as increasing treatment time and temperature. Experimental data of C* was described by combined model better than zero and first order kinetics models due to having highest determination coefficients (R 2 ) ( Table 4). The kinetic parameters of combined model were given in Table 4. The highest values were observed at 60°C. In each temperature, found nearly two times higher than Maillard reaction predominates over pigment destruction [31] even though, model fits were revealed that change in C* can not be explained as simple as one step zero or first order kinetics due to poor determination coeffici 0.7301; 0.5081-0.7965, respectively. Reyes Cisneros-Zevallos [34] have been reported that the decrease in chroma values would be related to the degradation of anthocyanins. Wrolstad et al. [30] reported that a confoulding phenomena regarding chroma is that it will increase with pigment concentration to a maximum, and then decrease as the colour darkens. At course of ; Article no. BJAST.19193 ) value of cornelian cherry concentrate during heating ) is a measure of chromaticity, which denotes the purity or saturation of the was calculated from Eq (9). Fig. 4 value of cornelian cherry concentrate during heating at 60, 70 and value was 55.4%, 59.9% and 68.1% for heating at 60, 70, 80°C, * value decreased < 0.05) ( Table 2) with time and That is, stability of red colour of cornelian cherry concentrate decreased as increasing treatment time and temperature.
was described by an zero and first order kinetics models due to having highest ) ( Table 4). The kinetic parameters of combined model were given in Table 4. The highest values were In each temperature, k o values wo times higher than k 1 , that is Maillard reaction predominates over pigment even though, model fits were can not be explained as simple as one step zero or first order kinetics due to poor determination coefficients, 0.4272-0.7965, respectively. Reyes and have been reported that the decrease in chroma values would be related to the degradation of anthocyanins. Wrolstad et reported that a confoulding phenomena ing chroma is that it will increase with pigment concentration to a maximum, and then decrease as the colour darkens. At course of heat treatment, degradation of anthocyanins was 63.77%, 71.50% and 89.37% for heating at 60, 70, 80°C, respectively. However, no statistically significant (P > 0.05) correlation between anthocyanin degradation at 60°C can be caused by the defined phenomena due to the highest residual pigment concentration as compared to those at 70 and 80°C. In the same manner, undefinite trend of kinetic constants can also be caused by the same phenomena.
Hue angle (h*°) describes what the average person thinks of in speaking of colour (i.e., green, red, yellow, etc.) [32]. h*° is expressed in degrees, with 0 o corresponding +a* axis (r then continuing to 90 o for the +b* axis (yellow), 180° for -a* (green) and finally 270 (blue) [19]. h*° was calculated from Eq. (10) and The variation of h*° value of cornelian cherry concentrate during heating at 60, 70 and 80 (Fig. 5). Increase in h*° value was 64.0%, 60.0% and 76.0% for heating at 60, 70, 80°C, respectively. Ignoring the poor fit of 70°C, it was seen that h*° value increased significantly ( 0.05) ( Table 2) with increasing time and treatment temperature (shifting toward Parameters of combined kinetic model for lightness*, chroma*, hue* and TCD given in Table 4. In each temperature, the rate of colour formation is lower than the rate of colour destruction based upon pigment destruction 9 degradation of anthocyanins was 63.77%, 71.50% and 89.37% for heating at 60, no statistically > 0.05) correlation between C* and anthocyanin degradation at 60°C can be caused by the defined phenomena due to the highest residual pigment concentration as compared to In the same manner, e trend of kinetic constants can also be describes what the average person thinks of in speaking of colour (i.e., green, is expressed in corresponding +a* axis (red), for the +b* axis (yellow), a* (green) and finally 270° for -b* was calculated from Eq. (10) and value of cornelian cherry during heating at 60, 70 and 80°C value was 64.0%, 60.0% and 76.0% for heating at 60, 70, 80°C, respectively. Ignoring the poor fit of 70°C, it was value increased significantly (P < 0.05) ( Table 2) with increasing time and (shifting towards 90°). Parameters of combined kinetic model for TCD* values were given in Table 4. In each temperature, the rate of colour formation is lower than the rate of colour destruction based upon pigment destruction with lower k o values than k 1 . Increase in be associated to the formation of yellow chalcone species [34]. Yang et al. [25] reported that change in a* and h*° values would be related to the degradation of redness and anthocyanins. They reported that in most degradation studies, increase in h*° is used as an indicator for the degradation of anthocyanins. However, in this study there was no statistically significant correlation between anthocyanin degradation and h*° value for temperatures of 60, 70 and 80°C (P > 0.05).
TCD* is a colorimetric parameter used to characterize the variation of colour in foods calculated by Eq. (8). [18]. Fig. 6 shows the variation of TCD* value of cornelian cherry concentrate during heating at 60, 70 and 80 TCD* value at the end of heat treatment was 2.68, 2.90 and 3.31 for heating at 60, 70, 80°C, respectively. The TCD* value increased significantly (P < 0.05) ( Table 2) with time and treatment temperature. Combined kinetic described the data of TCD* better than zero and first order kinetics models (Table 4). In each temperature, since the ratio of kinetic constants k o and k 1 is greater than unity, Maillard reaction predominates over pigment destruction [ same order of reaction was found by other researchers [17,18,31].

(C*) value of cornelian cherry concentrate during heating at 60, 70 and 80°C
; Article no. BJAST.19193 . Increase in h*° value can be associated to the formation of yellow chalcone Yang et al. [25] reported that values would be related to the degradation of redness and anthocyanins.
degradation studies, is used as an indicator for the degradation of anthocyanins. However, in this study there was no statistically significant correlation between anthocyanin degradation r temperatures of 60, 70 and * is a colorimetric parameter used to characterize the variation of colour in foods calculated by Eq. (8). [18]. Fig. 6 shows the * value of cornelian cherry during heating at 60, 70 and 80°C. end of heat treatment was 2.68, 2.90 and 3.31 for heating at 60, 70, 80°C, * value increased < 0.05) ( Table 2) with time and Combined kinetic * better than zero and order kinetics models (Table 4). In each temperature, since the ratio of kinetic constants is greater than unity, Maillard reaction predominates over pigment destruction [31]. The found by other during heating