Partial Substitute of Sugar with Date Concentrate in the Peach / Apple Juice and Study Physicochemical / Color Properties of Blend Fruit Juice

The main aim of this study is the substitution of sugar with date concentrate in the fruit juice and blend fruit juice, for this purpose date concentrate was used as a sugar substitute in the blend of peach and apple juice. The effect of five factors including; sugar syrup (%w/w), date concentrate (%w/w), apple concentrate (%w/w), peach puree (%w/w) and storage time (day) on the physicochemical/color properties of juice samples were investigated. An experimental design based on a D-Optimal Combine Design (DOCD) was used to study the different factors affecting (in 5 levels) on the physicochemical/color properties of provided mixed fruit juices. Different quality indices, including acidity, vitamin C content, total phenolic content, antioxidant capacity, None Enzymatic Browning Index (NEBI), Hydroxyl Methyl Furfural (HMF), turbidity, color index and formalin index were measured and modeled. The obtained responses were analyzed and studied by Design-Expert software. Results showed that 1The sugar in fruit juice blend can be easily replaced by date concentrate, 2The blend fruit juice contains date concentrate has more HMF, vitamin C and NEBI indices than blend fruit juice contains sugar that is so important for human health, 3Storage time don’t have a significant effect on the turbidity, color parameters (L∗, a∗ and b∗) and antioxidant properties of fruit juices.


INTRODUCTION
Consumption of fresh fruit is often replaced by the intake of fruit juices, due to their convenience and ability to quench thirst.It is expected that fresh fruits will be exempt from health and nutritional claims, it is therefore important to evaluate their chemical composition and biological value (Tamuno and Onyedikachi, 2015;Akazome, 2004;Nweze et al., 2015).Peaches include one of the most favorable fruits thanks to the delicious taste and the richness of nutrients.The texture of the skin is smooth and the fruit is sweet and watery.Peaches are rich in antioxidant, minerals and fiber (Sentanin and Rodriguez-Amaya, 2007;Toralles et al., 2006).That is why many people love to consume the fruits either at fresh or make it to be juices.Peaches contain high vitamin A which is good to reduce the risk of cancer on the glands and other tissues.The phosphor is beneficial to get rid of toxin in the kidney.Thanks to the beta carotene, this fruit can protect your eyes from any free radicals.Peaches are also full of fiber, which is good for the digestive system.Consuming peaches every day can increase your teeth and bones healthy since it is rich of minerals like fluoride and iron.With the fire, you can rely on these fruits to help you losing weight and getting rid of any helminth.The high amount of vitamin C has a big role to enhance your skin healthy as well (Sentanin and Rodriguez-Amaya, 2007;Toralles et al., 2006).Apple juice is a fruit juice made from the maceration and pressing of apple.The resulting expelled juice may be further treated by enzymatic and centrifugal clarification to remove the starch and pectin, which holds fine particulate in suspension and then pasteurized for packaging in glass, metal or aseptic processing system containers, or further treated by dehydration processes to a concentrate (Brillouet et al., 1996;Eisele and Drake, 2005;Wu et al., 2007).Due to the complex and costly equipment required to extract and clarify the juice from apples in large volume, apple juice is normally produced commercially.Apple juice has a significant concentration of natural phenols of low molecular weight (including chlorogenic acid, flavan-3ols and flavonols) and procyanidins.Apple juice has been shown to reduce oxidative stress in the brains of aging lab mice.Research suggests that apple juice increases acetylcholine in the brain, possibly resulting in improved memory (Brillouet et al., 1996;Eisele and Drake, 2005;Wu et al., 2007).Consuming fruits, including peaches in juice form could help the colon to absorb the nutrient more easily and quickly.Despite having some health benefits, apple juice is high in sugar.Fruit juices, smoothies and fruit drinks marketed to children and their parents contain "unacceptably high" levels of sugar, often as much in one small carton or bottle as a child should consume in a day, according to research.The researchers say tough action is needed to reduce the amount of sugar children consume in fruit drinks that are bought and sold on the assumption that they are healthy.The revelations of the high sugar levels in fruit juices and smoothies will dismay parents who may have turned to what they see as a healthier option than sugar-sweetened fizzy drinks such as colas and lemonades (Gibson, 1998;Schulze et al., 2004;St-Onge et al., 2004).Dates are among the sweetest of fruits, with up to 70% of their weight coming from sugar.Because of their sugar content, dates are higher in calories than most fruit.One Medjool date contains about 66 calories (Drake and Eisele, 1994;Farahnaky et al., 2016).The affluent presence of fibers in date concentrate helps to prevent constipation, intestinal disorders, heart problems and even, abdominal cancer.Prepared from the crown of sweets-dates, it is a powerhouse of energy and ideal for pregnant women to maintain their iron levels.Freshly squeezed concentrate, made by soaking dates in water overnight, contains fiber in surplus amounts, which enables proper bowel movements.Thus, people who are suffering from constipation can make use of this concentrate to obtain relief (Drake and Eisele, 1994;Farahnaky et al., 2016).The nicotine present in it is a known cure for intestinal disorders.Along with keeping a check on the production of harmful organisms, nicotine makes a fertile space for the growth of intestine-friendly bacteria.The concentrate when consumed as a part of healthy, balanced, nutrient rich diet aids in gaining weight.The natural presence of fats and sugars, along with proteins and vitamins enable the body to maintain its weight.Studies suggest intake of date concentrate with milk or with a cucumber paste to prevent overslimming (Abbèset al., 2013;Al-Farsi and Lee, 2008;El-Sharnouby et al., 2009).Concentrated dates syrup is rich in soluble fiber, making it easily digestible.Hence, it is ideal in controlling the loose bowels experienced in cases of diarrhea.The natural presence of sugars aids in getting rid of the tiredness experienced due to excessive defecation.Studies suggest that the concentrate can offer relief from abdominal cancer.It does wonders in healing cancer without any side effects (Drake and Eisele, 1994;Farahnaky et al., 2016;Abbèset al., 2013;Al-Farsi and Lee, 2008;El-Sharnouby et al., 2009).The fact that it contains sugars naturally enables it to supply extra energy essential to overcome the tiredness experienced due to chemotherapy.The presence of fluorine enables it to shield the teeth from cavities.However, due to the presence of natural sugars in excess, it is suggested to use it up calmly.
In this study the date concentrate was used as a sugar substitute in the blend fruit juice.The effect of five factors including; sugar syrup (%w/w), date concentrates (%w/w), apple concentrate (%w/w), peach puree (%w/w) and storage time (day) on the physicochemical/color properties of juice samples were investigated.

Reagents and chemicals:
The date and apple concentrate and peach puree was provided from urum-Marian and shahdbab-pars company, Urmia, Iran and were stored in refrigerator in front of using.All organic compounds were purchased from Merck.
Fruit juice preparation: After the standardization of apple and date concentrate and peach puree, these three different juices were diluted with deionized water to Brix 13̊ then mixed with each other and sugar syrup in the different percent according to the experimental design (Table 1).
Total phenol determination:The total phenolic content of the juice samples was determined by the Folin-Ciocalteu method (Eisele and Drake, 2005).
Briefly, 1 mL juice samples mixed with 5 mL of Folin-Ciocalteu reagent (0.2 Mol/L) for 3 min, followed by the addition of 4 mL of 7.5% (w/v) sodium carbonate.
The mixture was allowed to stand for a further 120 min in the dark and absorbance was measured at 765 nm.The total phenolic content was calculated from the calibration curve based on Gallic acid concentration (10-1000 mg/L) and the results were expressed as mg of Gallic acid equivalent per liter of juice samples.

Formalin index:
The formalin index of the juice samples was determined by the potentiometric titration method as the following: Briefly, NaOH (0.1 M) was added to 25 mL juice sample to reach pH = 8.1, followed by the addition 10 mL formaldehyde and stirred well.Finally the NaOH (0.1 M) gradually was added to the mix to pH = 8. 1 and the volume of consuming NaOH was recorded.The formalin index was calculated: Nonenzymatic Browning Index (NEBI): Ethyl alcohol (5 mL; 95% w/w), was added to 5 mL of juice sample, centrifuged (10 min) and the absorbance of the supernaant was read at 420 nm.The value obtained was considered as the Nonenzymatic Browning Index (NEBI).

Hydroxymethylfurfural:
The Keeney and Bassette (1959) method was utilized as follows: 2 mL of the supernatant (from the NEB test described above), 2 mL (120 g/kg) 3-chloroacetic acid (TCA) and 2 ml 0.025 mol/L Thiobarbituric Acid (TBA) were mixed in 16-mL screw-cap test tubes.The test tubes were placed in a water bath at 40±0.5°C, heated for 50 min and then cooled immediately with tap water to approximately 25°C.The absorbance measured at 443 nm was defined as the quality index utilized to quantify HMF.The actual HMF was read from a calibration curve of HMF ranging from 0 to 1000 mg/L.

Antioxidant activity determination by DPPH:
The antioxidant activity of the juice samples was determined by the 1, 1-Diphenyl-2-Picryl-Hydrazyl (DPPH) assay.Briefly, 2 mL methanol solution (include 100 μl/L of juice sample) were mixed with 2 mL methanol solution (include 0.002% DPPH) and incubated in the dark at room temperature for 1 h.The absorbance of the mixture was then measured at 517 nm.Ascorbic acid was used as a positive control.The ability of the sample to scavenge DPPH radical was determined from: where, A = Control sample absorbance B = Juice sample absorbance Turbidity determination: The turbidity of apple concentrates samples was determined by turbidimeter (N2100, HACH, United State).Firstly the turbidimeter instrument was calibrated in the 0 degrees (100% transmission) by deionized water, then fruit juice sample was put in the cell and the shown number as turbidity was recorded.In the fruit juice samples, high color and clarity (near to 100) and low turbidity (near to 0) show the high quality of samples.

Color determination:
The apparent color of juice samples was determined by a Hunter lab system (Colorflex, United State) based on a color system (L * , b * a * ).In addition to the hue angle and chroma were analyzed as the following: To study the effect of these factors on the responses a D-Optimal Combine Design (DOCD) was used.Five variables, including apple, peach and date concentrate and sugar percent (% W/W) and storage time of juice samples (all in five levels) were investigated.In Table 1 and 2, the 5 processing variables as factors, levels and experimental design are given.These tables also present the evaluated responses including, vitamin C, acidity, formalin index and antioxidant activity (Table 1) and NEBI, HMF, turbidity and total phenol (Table 2).Table 3 shows the list of juice sample color properties including L*, a*, b*, chroma and Hue angle for each experimental run.The Design-Expert software (version 7) was used to perform statistical analysis.Initially, the full term second order polynomial response surface models were fitted to each of the response variables, according to the following equation:     Where possible, stepwise deletion of terms was appliedtoremove thestatistically nonsignificantterms, so simplifying the model.However, when the exclusion of such terms from the model decreases R 2 (adjusted) and increases the estimator of the variance S, the term was included in the model.The statistically non-significant linear terms also remained in the model when the respective quadratic or interactive effects were statistically significant.The quadratic polynomial models for all responses accompanied by F values and corresponding R 2 was used, the estimated regression coefficients summarized in Table 4 and 5.

Contour plots of juice physicochemical properties based on variables:
The contour plots based on the model function were used to predict responses to survey influence of each variable on the analyzed physicochemical properties.
Figure 1 shows a contour plot of juice vitamin Cversus three factors (sugar percent, date concentrates percent and storage time).Results show that vitamin C content of blend juice samples is decreased by increasing storage time and increasing of date concentrate in the juice samples can increase vitamin C content that has a beneficial effect on the human health.Esteve et al. (2005) research showed that the vitamin C concentration in orange juice was decreased by increasing storage time that their results is according to the our results.
Figure 2 shows three dimensional plots of acidityversus five factors (apple juice, peach juice, date concentrate and sugar percent and storage time).Results show that all variables have affected the acidity and there are some interactions between variables.The storage time has a little effect on the acidity and increasing of date concentrate percent against sugar percent increases slightly the acidity.The peach percent of the blend juice strongly affects the acidity.The blend juice acidity is increased by increasing peach percent.In the similar researches the obtained results showed that increasing of storage time increases the acidity of fruit juice by microbial activity and fermentation process (Esteve et al., 2005).
Figure 3 shows three dimensional plot of formalin indexversus five factors (apple juice, peach juice, date concentrate and sugar percent and storage time).Results show that all variables have affected the formalin index and there are some interactions between variables.The formalin index of blend juice samples is increased by increasing of peach percent and increasing of date concentrate content of juice sample cause to increase formalin index.Increasing of storage time causes to decrease formalin index.Figure 4 shows a contour plot of antioxidantversus variables.Results show that there are not linear relations between variables and antioxidant activity.The antioxidant activity of blend juice is increased byincreasing of peach juice percent.According to the similar researches the antioxidant activity of fruit juices is decreased by increasing storage time (Tavarini et al., 2008).
Figure 5 shows a contour plot NEBIversus variables.Results show that there are not linear relations between variables and antioxidant activity.The NEBI of blend juice is increased by increasing of    date concentrate percent.In the similar research nonenzymatic browning of peach juice concentrate during storage was obtained (Buedo et al., 2001).
Figure 6 shows three dimensional plots of HMF based on five factors (apple juice, peach juice, date concentrate and sugar percent and storage time).
Results show that all variables have affected the HMF and there are some interactions between variables.The HMF of blend juice samples is increased by increasing of date concentrate content.Burdurlu et al. (2006) research confirm the results that were obtained in this research.Figure 7 shows contour plot and three dimensional plots of turbidityversus five factors (apple juice, peach juice, date concentrate and sugar percent and storage time).Results show that all variables have affected the turbidity and there are some interactions between variables.The turbidity of blend juice samples is increased strongly by increasing of peach percent and increasing of date concentrate content of juice sample and storage time cause to increase turbidity slightly.
Figure 8 shows three dimensional plots of total phenol based on five factors (apple juice, peach juice, date concentrate and sugar percent and storage time).Results show that all variables have affected the total phenol and there are some interactions between variables.The phenol of blend juice samples is increased by increasing of apple juice content.Almost the similar results were obtained in the previous researches (Suárez-Jacoboet al., 2011).

Contour plots of juice color properties based on variables:
The contour plots based on the model function were used to predict responses to survey influence of each variable on the analyzed color properties.Figure 9 shows contour plot and three dimensional plots of L * , a * and b * versus five factors (apple juice, peach juice, date concentrate and sugar percent and storage time).Results show that all variables have affected the L * , a * and b * and there aresome interactions between variables.The L * , a * and b * are decreased by increasing of apple juice percent, b * is decreased by increasing of date concentrate percent.The L * , a * and b * are almost constant in the different storage time.
Figure 10 shows contour plot and three dimensional plots of hue angle versus five factors (apple juice, peach juice, date concentrate and sugar percent and storage time).Results show that all variables have affected the hue angle and there are some interactions between variables.The hue angle is decreased by increasing of date concentrate.

CONCLUSION
In this study date concentrate was used as a sugar substitute in the blend fruit juice.The Effect of five factors including; sugar syrup (%w/w), date concentrate (%w/w), apple concentrate (%w/w), peach puree (%w/w) and storage time (day) on the physicochemical/color properties of juice samples were investigated.An experimental design based on a D-Optimal Combine Design (DOCD) was used to study the different factors effect on the physicochemical/color properties of mixed fruit juices.Different quality indices, including acidity, vitaminCcontent, total phenolics content, antioxidant capacity, NEBI, HMF, turbidity, formalin index and color properties (L * , a * , b * , bi and hue angle) were measured.Results showed that:  Vitamin C content of blend juice samples is decreased by increasing storage time and increasing of date concentrate in the juice samples can increase vitamin C content that has a beneficial effect on the human health  The peach percent in the blend juice strongly affects the acidity.The blend juice acidity is increased by increasing peach percent  The L * , a * and b * are decreased by increasing of apple juice percent, b * is decreased by increasing of date concentrate percent.The L * , a * and b * are almost constant in the different storage time  The NEBI of blend juice is increased by increasing of date concentrate percent

Fig. 4 :
Fig. 4: Contour plot of antioxidant activity based on variables

Fig. 6 :
Fig. 6: Three dimensional plots of HMF based on variables

Fig. 7 :
Fig. 7: Contour plot and three dimensional plot of turbidity based on variables

Fig. 9 :Fig. 10 :
Fig. 9: Contour plots and three dimensional plots of L*, a* and b* based on variables

Table 1 :
List of experiments in the DOCD and the responses including vitamin C, acidity, formalin index and antioxidant activity

Table 1 :
Continue Factors

)
Experimental design: Substitution of sugar by date concentrate in blend juice of apple and peach juices can affect the physicochemical and color of the products.So the apple, peach and date concentrate and sugar percent (% w/w) and storage time of juice samples as five factors that affect physicochemical/color properties of mix fruit juice were studied.The studied physicochemical/color properties include acidity, formalin index, total phenolic compounds, HMF, NEBI, Vitamin C content, antioxidant activity, turbidity and color properties (L*, b* a*, Hue angle, chroma and bi).

Table 2 :
List of experiments in the DOCD and the responses including NEBI, HMF, turbidity and total phenol

Table 3 :
List of juic samples color properties include L*, a*, b*, chroma and Hue angle for each experiment run