Comparing the antioxidant properties and volatile compounds of carrot-orange juice blend processed through varied chemical, pasteurization and ultrasound conditions

Graphical abstract

Highlights

• •The effect of ultrasonication (US) and chemical preservation on the quality of the carrot-orange juice blend was determined.
• •Storage study of juice was conducted for up to 21 days.
• •Phenol, antioxidant capacity, DPPH and reducing the power of juice blend were evaluated.
• •US positive effect on nutritional status of juice blend as it enhanced functional properties.

Abstract

Ultrasound technique is one of the green technologies that is being utilized widely for varying food processes. Our aim in this study was to carry out ultrasonication, pasteurization and chemical preservation (Potassium metabisulfite) techniques on a carrot-orange juice blend. Additionally, the effect of these treatments on the storage period of about 21 days was also determined. The study displayed an array of results under the effect of different treatments. Throughout the storage period of 21 days’ significant results were presented by the carrot juice blend subjected to the ultrasound technique (25 min) giving the highest values for total phenolic content (25.56 ± 1.29 mg GAE/100 mL), total antioxidant activity (573.48 ± 2.29 mg Trolox /100 mL), DPPH (32.32 ± 1.83 %) and reducing power (45.45 ± 1.92 mg AAE/100 mL) with least deterioration, followed by the blends treated with potassium metabisulfite (KMS) and pasteurization. The physicochemical analysis showed a non-significant effect of treatments on pH and total soluble solids (^oBrix) of carrot-orange juice blends whereas, the changes in color parameters L*, a* and b* were noted to show changes in treated blends. Similarly, the results for the GC–MS quantification of volatile compounds displayed the highest concentrations in the ultrasonicated blends as compared to other techniques. The peak quantity was obtained for the hexanal (9903.43 ± 7.61 μg.kg⁻¹) followed by 3-Methylbutanal (2638.7 ± 5.44 μg.kg⁻¹), terpinolene (2337.16 ± 5.28 μg.kg⁻¹), elemicin (2198.28 ± 5.28 μg.kg⁻¹), myristicin (1936.62 ± 6.72 μg.kg⁻¹). The use of sonication can effectively enhance the nutritional qualities of juice, as perceived by consumers.

1. Introduction

Fruits and their products are widely recognized around the world for their nutritional value and the abundance of bioactive compounds they contain. Therefore, they are highly recommended for inclusion in diets [1]. Fruit juices are known to be rich in antioxidant and phytonutrient compounds, which offer protection against various diseases. Regular consumption of fruit juices has been shown to decrease the occurrence of cancer and cerebrovascular diseases, leading to a lower mortality rate [2]. To enhance the taste and nutritional value of juices and reduce food waste, blending juices from different fruits is a strategy that can be employed. This approach also makes it possible to use under-utilized fruits, which improves their economic value [1].

For many years, thermal treatment has been employed as a means of prolonging the shelf life of fruit juices. However, this technique can have adverse effects on both the nutritional and sensory characteristics of the products. The rising demand for fresh and nutritious juices has resulted in an increased focus on the use of mild processing techniques [3]. To ensure consumer safety, recent FDA regulations mandate that processors reduce microorganisms in juice products by 5 logs. This requirement has created a need for processing methods that are both effective and gentle, in order to mitigate the risk of foodborne illnesses associated with consuming unprocessed juice products [4], [5]. The recent trend of consumers being more health-conscious and aware of their dietary needs has resulted in a surge in demand for minimally processed food products that can maintain their quality and have an extended shelf life. The quality, safety, and shelf life of food products are heavily influenced by the processing methods utilized. The effectiveness of thermal processing techniques (pasteurization) in preserving food quality and safety while increasing shelf life is widely recognized. However, these methods are known to have a detrimental impact on the nutritional value of food by causing a significant depletion of essential nutrients [6].

To combat this issue, alternative processing methods like ultrasonication are being explored as substitutes for pasteurization in the processing of fruit juices. Ultrasonication is a practical alternative since it can preserve the health benefits and consumer appeal of fruit juices while also providing pasteurization [7], [8]. As a result of the increased demand for fresh and minimally processed food items, the food industry is actively seeking novel approaches that can prolong the shelf life of food products while preserving their nutritional integrity [9]. Alternative or innovative processing methods are being researched to create fresh and nourishing food products without the use of chemical preservatives or the application of heat [10]. Of these techniques, ultrasound treatment is gaining favor with consumers who prioritize their health. The food industry is investigating non-thermal methods of processing to manufacture food products that sustain nutritional and sensory qualities with minimal damage [1]. Included among these technologies are osmotic dehydration, membrane filtration, high-pressure treatment, pulse electric field, ultrasound, and irradiation. Before these emerging technologies can be adopted by the food industry, their economic viability must be assessed. Studies in this field are currently underway globally [11].

The carrot (Daucus carota L.), which has a delightful flavor, exceptional nutritional value, and several health advantages, is a root vegetable. Carrots possess therapeutic properties such as being anti-anemic, anticancer, antioxidant, sedative, and healing agents [12]. Carrots' high content of carotenoids, phenolic compounds, and ascorbic acid is responsible for their significant antioxidant capacity [13], [14]. Due to their perishable nature, carrots are often processed into a variety of products, including juices, despite being commonly consumed as fresh vegetables. Undesirable browning reactions may occur during the processing and storage of carrot juice, leading to discoloration of the product due to the condensation of phenolic compounds. Carrots are abundant in dietary fiber, carotenoids, vitamin K, magnesium, and several other crucial nutrients [15]. Drinking carrot juice has also been associated with other advantageous physiological effects, including decreased DNA damage, elevated levels of antioxidants, and reduced inflammation [16].

Orange juice is the main product of orange processing, valued by consumers globally for its aroma, color, and health benefits, which include a lower body mass index (BMI) and a healthier diet for children and adults [17]. Orange juice is abundant in pectin, flavonoids, phenolic compounds, and vitamin C. The main flavonoids present in citrus species include hesperidine, narirutin, naringin, and eriocitrin [18]. According to the World Health Organization, citrus fruits, especially oranges, have been found to contain cardio-protective compounds such as vitamin C, carotenoids, and flavonoids, and to provide protection against cardiovascular diseases by reducing homocysteine levels [19]. Nevertheless, the quality of orange juice may vary due to variations in processing methods.

The objective of the present study was to assess and compare the impact of various preservation methods, including chemical preservation (potassium metabisulfite (KMS), pasteurization, and ultra-sonication on the physicochemical properties, volatile profile and bioactive compounds of a carrot-orange juice blend.

2. Materials and methods

2.1. Procurement of raw materials

High-quality and fully ripened carrots and oranges were procured from a local market in Lahore, Pakistan. Local suppliers in Lahore provided other necessary materials, such as carboxy methyl cellulose as a preservative and plastic bottles.

2.2. Preparation of fruit juice

2.2.1. Pre-treatment of raw materials

The initial stage of the process entailed sorting the carrots and oranges to distinguish fully ripe and good-quality fruits. Both the carrots and oranges were washed thoroughly for the removal of dust and dirt particles. Subsequently, the sorted and washed fruits (carrots and oranges) were dried in the shade to remove excess water.

2.2.2. Preparation of juice blends

To obtain the fruit juice, the oranges were manually extracted, whereas the carrots were peeled, trimmed, and crushed in a juice extractor to extract their juice. Afterwards, the juices were passed through a double-layer muslin cloth to filter out any solid particles. A total of six juice blends were prepared by blending carrot and orange juices in different ratios, including 100:0, 90:10, 80:20, 70:30, 60:40, and 50:50. The ratio of 70:30 of carrot and orange juices, which received the best sensory response, was chosen for further analysis.

2.2.3. Carrot-orange juice blend processing

In this study, carrot-orange juice blends (100 mL) were processed with varied conditions of chemical preservation, pasteurization, and ultrasonication (Table 1). For chemical preservation, KMS (Potassium-meta bisulphite) at 0.5, 1, and 1.5 % concentration was used for the preservation of carrot-orange juice blend. Similarly, in the case of pasteurization, carrot-orange juice blends were processed at 72 °C for three different time intervals i.e. 5, 10, & 21 s. Whereas, for ultrasound treatment, carrot-orange juice blends (100 mL) were sonicated (SB-600DTY, Ningbo Scientz Biotechnology Company Limited, Ningbo, China) at 28 kHz (frequency), 20 °C (temperature), and 70 % (power radiation) for 5, 15, & 25 min. The temperature of samples was maintained and regulated using a water bath [20]. The carrot-orange juice samples were stored under refrigeration conditions till further analysis (Table 2).

Table 1.

Treatments conditions of control, KMS, pasteurization and ultrasonication treatments.

Treatments	Details	Details
T0	Control	–
T1	KMS	0.5 %
T2		1 %
T3		1.5 %
T4	Pasteurization	5 sec
T5		10 sec
T6		21 sec
T7	Ultrasonication	5 min
T8		15 min
T9		25 min

Table 2.

Treatment table for quantifying the aromatic volatile compounds in the carrot-orange juice blend.

Treatments	Details
T (KMS-1.5%)	Potassium metabisulfite (1.5 %)
T (HTST-5 sec)	High-temperature short time (5 sec)
T (U-25 min)	Ultrasonication (25 min)

2.2.4. Carrot-orange juice blend analysis

2.2.4.1. Total polyphenol content (TPC)

Spectrophotometric analysis of total phenolics in the carrot-orange blend juice was conducted using the Folin-Ciocalteu reagent method [21]. To conduct the analysis, 0.5 mL of known concentration of carrot-orange juice blend samples were mixed with 1 mL of a 10 % solution of Folin-Ciocalteu reagent. After thoroughly mixing the sample were allowed to incubate at room temperature for 2 h, and then the absorbance was measured at 765 nm using a spectrophotometer (Q898DRM, Quimis, Brazil). The results of the analysis were expressed as the milligram gallic acid equivalents per 100 mL (mg GAE/100 mL) of each sample of the carrot-orange juice blend. This assay was conducted in triplicates.

2.2.4.2. Total antioxidant capacity (TAC)

An aliquot of 0.1 mL of a sample solution containing a reducing agent in water, methanol, ethanol, dimethyl sulfoxide, or hexane, was mixed with 1 mL of reagent solution. The reagent solution consisted of 0.6 M sulfuric acid, 28 mM sodium phosphate, and 4 mM ammonium molybdate, and the mixture was placed in an Eppendorf tube. The tubes were then capped and placed in a thermal block for 90 min of incubation at 95 °C. After the samples were cooled to room temperature, their absorbance was measured at 695 nm against a blank using a spectrophotometer (Q898DRM, Quimis, Brazil). A standard blank solution was prepared by incubating 1 mL of reagent solution and an appropriate volume of the same solvent used for the samples under the same conditions. Calibration curves were established using Trolox as the standard, and the results were reported in milligrams of Trolox equivalent per 100 mL of juice [22]. This assay was conducted in triplicates.

2.2.4.3. Reducing power ability

The method described by Hegazy and Ibrahim [23] was utilized to determine the reducing capacity of the carrot-orange juice blend by spectrophotometry. The results are expressed as milligram ascorbic acid equivalents per 100 ml of juice (mg AAE/100 mL). The experiments were repeated thrice and an increase in absorbance of the sample mixture indicated an increase in reducing potential. This assay was conducted in triplicates.

2.2.4.4. DPPH free radical scavenging activity

The procedure for assessing the ability of carrot-orange juice blends to scavenge DPPH-free radicals was carried out according to the methodology described by [24], [25]. A mixture was prepared by combining 2 mL of juice sample with 2,000 µL of DPPH. The mixture was then stored in a dark environment at room temperature for 30 min. Afterwards, the absorbance of the mixture was measured at 517 nm using a spectrophotometer (Q898DRM, Quimis, Brazil). A similar procedure was carried out for the blank using ethanol, and the decrease in absorbance due to the proton-donating activity was measured at 517 nm using a spectrophotometer. This assay was conducted in triplicates. The DPPH radical scavenging activity was calculated using the following formula:

$$\mathit{DPPH}radicalscavengingactivity(\%)=[(A0-At)/A0]x100$$

The symbol At represents the absorbance of the carrot-orange juice blends, while A0 stands for the absorbance of the control.

2.2.4.5. Physicochemical analysis

Physico-chemical analyses were employed to assess the chemical composition and physical properties of the carrot-orange juice blend. These analyses were conducted in triplicates.

2.2.4.5.1. Total soluble solids (°Brix)

The digital refractometer manufactured by Shanghai Precision and Scientific Instrument Co., Shanghai, China, was utilized to measure the total soluble solids (TSS) present in the carrot-orange juice samples at 25 ± 1 °C. The degree Brix was used to express the values obtained.

2.2.4.5.2. pH

The pH of the carrot-orange juice samples was determined at 25 ± 1 °C using a digital pH meter (Thermo Fisher Scientific, Inc., MA, USA). Before use, the pH meter was calibrated with buffers having pH values of 4.01, 6.86, and 9.18. The obtained pH values were recorded.

2.2.4.5.3. Color

The color of the carrot-orange juice blend was assessed using the Hunter Lab Color Quest XE colorimeter in terms of L* (brightness), a* (ranging from greenness [-] to redness [±]), and b* (ranging from blueness [-] to yellowness [±]).

2.3. Selection of best treatments

Depending upon the results of total phenolic contents, total antioxidant activity, reducing power ability, DPPH scavenging activity, and physicochemical analysis presented in Table 3, Table 4, Table 5, Table 6, Table 7, one best treatment from each processing condition (pasteurization, chemical preservation, and ultrasonication) was chosen for further analysis to quantify the aromatic volatile compounds in the carrot-orange juice blend using GC–MS. The table below shows the treatment details for GC–MS quantification.

Table 3.

TPC (mg GAE/100 mL) of the juice blends.

Samples	0 day	7th day	14th day	21st day
T0 (control)	20.89 ± 1.55CDa	19.29 ± 1.98CDab	16.75 ± 1.25Dbc	13.67 ± 1.24Dc
T1 (KMS 0.5 %)	21.22 ± 0.67CDa	20.05 ± 1.47CDa	18.30 ± 1.15CDab	16.10 ± 2.05CDb
T2 (KMS 1 %)	21.98 ± 1.19CDa	20.89 ± 0.95CDa	19.21 ± 1.76CDab	17.01 ± 1.62CDb
T3 (KMS 1.5 %)	22.53 ± 1.34BCa	21.43 ± 0.72BCDab	19.75 ± 1.53CDab	17.62 ± 2.23CDb
T4 (HTST 5 sec)	20.58 ± 1.28CDa	19.76 ± 1.31CDa	18.34 ± 1.45CDab	16.49 ± 0.88CDb
T5 (HTST 10 sec)	19.43 ± 2.11CDa	18.70 ± 1.45CDa	17.46 ± 0.98CDa	16.01 ± 1.95CDa
T6 (HTST 21 sec)	18.01 ± 1.12 Da	17.45 ± 1.65 Da	16.36 ± 1.11 Da	15.03 ± 1.15 Da
T7 (US 5 min)	23.19 ± 1.09BCa	22.66 ± 2.12BCa	21.69 ± 0.90BCa	20.28 ± 2.60BCa
T8 US 15 min)	26.22 ± 1.63ABa	25.81 ± 2.42ABa	24.97 ± 1.93ABa	22.78 ± 1.30ABa
T9 (US 25 min)	27.81 ± 0.88Aa	27.51 ± 1.48Aa	26.84 ± 2.69Aa	25.56 ± 1.29Aa

Note: Mean values with different small letters in the same row (a–c) differ significantly (p < 0.05) from each other. Similarly, mean values with different capital letters in the same column (A-D) differ significantly (p < 0.05) from each other. While mean values with the same letters in rows/column do not differ significantly.

Table 4.

Total antioxidant capacity (mg Trolox /100 mL) of the juice blends.

Samples	0 day	7th day	14th day	21st day
T0 (control)	523.91 ± 1.98 Da	479.55 ± 2.19Fb	408.95 ± 2.38Gc	339.09 ± 3.44Gd
T1 (KMS 0.5 %)	525.09 ± 4.91 Da	487.80 ± 2.33Eb	432.52 ± 1.94Ec	364.90 ± 3.19Fd
T2 (KMS 1 %)	526.12 ± 2.37CDa	490.91 ± 1.95Eb	439.69 ± 3.12Ec	379.96 ± 2.98Ed
T3 (KMS 1.5 %)	531.44 ± 2.41CDa	498.90 ± 1.72Db	449.98 ± 3.55Dc	399.01 ± 2.39Dd
T4 (HTST 5 sec)	490.89 ± 2.28Ea	461.61 ± 3.31 Gb	419.90 ± 2.45Fc	376.18 ± 1.88Ed
T5 (HTST 10 sec)	457.18 ± 3.65Fa	433.81 ± 2.48Hb	398.39 ± 3.98Hc	361.88 ± 4.09Fd
T6 (HTST 21 sec)	425.11 ± 2.12 Ga	407.01 ± 3.69Ib	375.94 ± 2.75Ic	342.27 ± 3.15Gd
T7 (US 5 min)	534.77 ± 4.06Ca	514.98 ± 2.19Cb	487.19 ± 3.90Cc	449.17 ± 2.60Cd
T8 US 15 min)	601.31 ± 4.63Ba	582.37 ± 2.47Bb	554.58 ± 3.93Bc	522.15 ± 1.50Bd
T9 (US 25 min)	639.09 ± 2.88Aa	623.99 ± 3.48Ab	602.55 ± 2.69Ac	573.48 ± 2.29Ad

Note: Mean values with different small letters in the same row (a–d) differ significantly (p < 0.05) from each other. Similarly, mean values with different capital letters in the same column (A-I) differ significantly (p < 0.05) from each other. While mean values with the same letters in rows/column do not differ significantly.

Table 5.

Reducing power (mg AAE/100 mL) of the juice blends.

Samples	0 day	7th day	14th day	21st day
T0 (control)	41.01 ± 1.59CDEa	39.26 ± 0.81DEab	35.70 ± 1.52Db	31.45 ± 1.42Dc
T1 (KMS 0.5 %)	41.47 ± 0.67CDEa	39.82 ± 1.75CDEa	37.44 ± 1.51Dab	34.29 ± 2.35CDb
T2 (KMS 1 %)	42.39 ± 1.91BCDa	41.15 ± 0.59CDEa	39.32 ± 1.67CDab	36.92 ± 0.62BCb
T3 (KMS 1.5 %)	43.07 ± 0.43BCDa	41.62 ± 1.27CDab	39.72 ± 0.53CDb	37.11 ± 1.23BCc
T4 (HTST 5 sec)	41.02 ± 2.28CDEa	39.92 ± 0.31CDEab	38.17 ± 0.54CDab	36.05 ± 1.88BCDb
T5 (HTST 10 sec)	39.75 ± 1.11DEa	38.67 ± 0.64DEab	37.16 ± 1.29Dab	35.38 ± 2.13CDb
T6 (HTST 21 sec)	38.13 ± 0.49Ea	37.24 ± 0.65Eab	35.89 ± 1.81Dab	34.26 ± 1.51CDb
T7 (US 5 min)	44.15 ± 2.09BCa	43.41 ± 2.22BCa	42.25 ± 1.90BCa	40.62 ± 2.06ABa
T8 US 15 min)	46.40 ± 1.36ABa	45.81 ± 2.28ABa	44.73 ± 1.33ABa	42.29 ± 2.02Aa
T9 (US 25 min)	48.28 ± 0.78Aa	47.83 ± 1.84Aa	46.91 ± 2.46Aa	45.45 ± 1.92Aa

Note: Mean values with different small letters in the same row (a–c) differ significantly (p < 0.05) from each other. Similarly, mean values with different capital letters in the same column (A-E) differ significantly (p < 0.05) from each other. While mean values with the same letters in rows/column do not differ significantly.

Table 6.

DPPH (%) of the juice blends.

Samples	0 day	7th day	14th day	21st day
T0 (control)	28.77 ± 1.01CDEa	27.18 ± 2.12CDab	23.96 ± 1.09Db	19.84 ± 0.98Dc
T1 (KMS 0.5 %)	29.10 ± 0.72CDEa	27.65 ± 2.10CDa	25.53 ± 1.63CDab	22.55 ± 1.93Db
T2 (KMS 1 %)	29.86 ± 0.94BCDa	28.61 ± 0.95 BCDa	26.83 ± 1.57CDab	24.52 ± 1.62Cb
T3 (KMS 1.5 %)	30.41 ± 1.23BCDa	29.06 ± 0.74BCDab	27.23 ± 1.51CDbc	24.68 ± 0.82BCDc
T4 (HTST 5 sec)	28.46 ± 1.29CDEa	27.44 ± 1.33CDa	25.75 ± 0.44CDab	23.72 ± 0.85CDb
T5 (HTST 10 sec)	27.31 ± 2.18DEa	26.36 ± 0.56CDab	24.94 ± 0.89Dab	23.34 ± 1.27CDb
T6 (HTST 21 sec)	25.89 ± 1.14Ea	25.16 ± 1.52 Da	23.87 ± 1.16 Da	22.34 ± 2.14 Da
T7 (US 5 min)	31.07 ± 1.03BCa	30.39 ± 2.07ABCa	29.30 ± 0.95BCa	27.74 ± 2.61ABCa
T8 US 15 min)	33.12 ± 1.36ABa	32.63 ± 2.24ABa	31.72 ± 1.39ABa	29.47 ± 1.92ABa
T9 (US 25 min)	34.71 ± 0.78Aa	34.36 ± 1.74Aa	33.64 ± 2.86Aa	32.32 ± 1.83Aa

Note: Mean values with different small letters in the same row (a–c) differ significantly (p < 0.05) from each other. Similarly, mean values with different capital letters in the same column (A-E) differ significantly (p < 0.05) from each other. While mean values with the same letters in rows/column do not differ significantly.

Table 7.

Physico-chemical properties of carrot-orange juice blend.

Treatments	pH	oBrix	L*	a*	b*
T0 (control)	4.91 ± 0.10NS	13.09 ± 0.44 NS	44.73 ± 0.91d	22.92 ± 0.43b	31.90 ± 0.89e
T1 (KMS 0.5 %)	5.01 ± 0.90 NS	13.05 ± 0.37 NS	46.27 ± 0.41 cd	26.10 ± 0.19a	34.55 ± 0.54 cd
T2 (KMS 1 %)	4.89 ± 0.45 NS	13.02 ± 0.89 NS	48.14 ± 0.31abc	27.77 ± 0.58a	33.71 ± 0.39de
T3 (KMS 1.5 %)	5.05 ± 0.20 NS	12.95 ± 0.18 NS	48.58 ± 0.89abc	28.13 ± 1.09a	35.24 ± 1.04 cd
T4 (HTST 5 sec)	5.13 ± 0.27 NS	12.86 ± 0.65 NS	47.60 ± 0.76bc	28.45 ± 0.91a	36.02 ± 0.10c
T5 (HTST 10 sec)	5.09 ± 0.51 NS	13.00 ± 0.21 NS	49.19 ± 0.48ab	27.91 ± 1.32a	38.35 ± 0.88b
T6 (HTST 21 sec)	4.99 ± 0.98 NS	12.58 ± 0.47 NS	49.88 ± 1.29ab	27.12 ± 0.86a	39.06 ± 0.53b
T7 (US 5 min)	5.10 ± 0.48 NS	13.01 ± 1.10 NS	47.48 ± 0.42bc	19.51 ± 0.56c	38.88 ± 1.05b
T8 US 15 min)	4.90 ± 0.59 NS	12.87 ± 0.45 NS	48.72 ± 1.25a-c	20.59 ± 0.66bc	40.01 ± 0.25b
T9 (US 25 min)	4.86 ± 0.44 NS	13.11 ± 0.88 NS	50.19 ± 1.17a	22.34 ± 1.20b	44.12 ± 0.72a

Note: Mean values with different small letters in the same column (a–e) differ significantly (p < 0.05) from each other. While NS means non-significant.

2.4. Solid-phase micro-extraction (SPME)

The extraction of volatile compounds from carrot-orange juice samples was carried out using the HS-SPME (Headspace Solid-Phase Microextraction) method. To extract the volatile compounds from the carrot-orange juice samples, a 20 mL headspace (HS) vial containing 5 g of the blend, 2 g of sodium chloride, and 1 μL (0.16 mg.kg) of 1,2-dichlorob. Subsequently, the vial was transferred to a thermostatic water bath and maintained at 40 °C for 20 min. The fiber used for extraction, consisting of 50/30 μm DVB: divinybenzene/CAR: carboxen/PDMS: polydimethylsiloxane, was placed approximately 1 cm above the liquid surface and exposed to the headspace of the sample for 40 min at 40 °C. The extraction process involved stirring the fiber at a speed of 600 r/min The GC instrument, equipped with an MS-detector, was used to subject the extraction fiber to desorption at 250 °C in the injection port for 5 min [26].

2.5. GC–MS analysis

Volatile compounds were separated and identified using an Agilent Technologies gas chromatograph (GC) model number 7890 equipped with a mass selective detector (MS) model number 5973C. Two separate columns were used for the analysis of volatile compounds. An HP-INNOWax fused-silica capillary column (L × D: 60 m × 0.25 mm with 0.25 mm thickness of film) manufactured by Agilent, Santa Clara, CA was used as the first column. Herein, DB-5 fused-silica capillary column was employed as the second column in this experimentation. This column was also developed by Agilent, Santa Clara, CA. Helium was used as the carrier gas, and it constantly flowed at a rate of 1 mL/min in a constant flow mode. The injection port was maintained at a temperature of 250 °C and set to operate in spitless mode for 3 min. At the start, the oven temperature was held at 40 °C for 6 min. The temperature was then ramped up at a rate of 3 °C/min until it reached 160 °C, and subsequently held at this temperature for the duration of the analysis. In the final 10 min of the analysis, the temperature was increased to 230 °C. An electron impact mode (EI) with an energy of 70 electron volts (eV) was utilized for the mass spectrometry analysis. The mass spectrometer scanning was performed from 30 to 400 atomic mass units (amu). The identification of volatile compounds was accomplished by a combination of authentic standards, retention index (RI), and comparison with the Mass Spectral Library (NIST08, Wiley7n. I). The retention index (RI) was determined by using a series of n-alkanes (C7-C30), having 1000 mg L^-1 content in n-hexane [27].

2.6. Statistical analysis

The mean values ± standard deviations of the collected data were reported. A completely randomized design (CRD) was conducted with one-way ANOVA and p < 0.05 was considered significant. Moreover, Tukey's HSD pairwise comparison test was used to assess the significant difference among mean values. For these purposes, Statistics 9.0 Software was used to perform statistical studies.

3. Results

3.1. Impact of different treatments on total phenolic content (TPC)

Table 3 shows the alterations in the TPC of the blend of carrot and orange juice blend under different treatments and throughout storage. The objective of the study was to assess the impact of chemical preservation, pasteurization, and ultra-sonication on the storage time of the juice blend. The findings indicated a notable rise in the TPC in the sonicated blends when compared to the control. At day 0, the TPC of the juice blend was highest in the T9 treatment (ultra-sonicated for 25 min) with 27.81 ± 0.88 mg GAE/100 mL, followed by T8 and T7 (ultra-sonicated for 15 and 5 min), which had 26.22 ± 1.63 mg GAE/100 mL and 23.19 ± 1.09 mg GAE/100 mL, respectively. The TPC was lower in the KMS treatments (T3, T2, & T1) with values of 22.53 ± 1.34, 21.98 ± 1.19, and 21.22 ± 0.67 mg GAE/100 mL, respectively. On the other hand, the HSTS treatments (T4, T5, & T6) demonstrated even lower values with 20.58 ± 1.28, 19.43 ± 2.11, and 18.01 ± 1.12 mg GAE/100 mL, respectively. However, there was a significant decrease in phenolic content in the control group T0, with the values decreasing from 20.89 ± 1.55 to 13.67 ± 1.24 mg GAE/100 mL at day 21. On the contrary, the juice blend subjected to ultra-sonication exhibited the least decline in phenolic content, with a reduction of only 25.56 ± 1.29 mg GAE/100 mL from the initial level of 27.81 ± 0.88 mg GAE/100 mL.

3.2. Impact of different treatments on total antioxidant capacity (TAC)

The results of the impact of treatments on the TAC of the carrot-orange juice blend are presented in Table 4, which demonstrated a comparable trend to the total phenolic content. The group with the lowest TAC was the control group T0, with a value of 523.91 ± 1.98 mg Trolox/100 mL, on day 0. The HTST treatments (T4, T5, & T6) exhibited lower values among the different techniques used, with T6 demonstrating the lowest capacity of 425.11 ± 2.12 mg Trolox/100 mL. HTST treatments (T4, T5, & T6) showed lower values, while the KMS treatments (T1, T2, & T3) displayed slightly higher values. Among the KMS treatments, T3 had the highest antioxidant capacity of 531.44 ± 2.41 mg Trolox/100 mL. The ultra-sonication treatments (T7, T8, & T9) showed the highest antioxidant capacity, and T9 had the highest value of 639.09 ± 2.88 mg Trolox/100 mL. The impact of storage resulted in a reduction in the antioxidant capacity of all treatments, with the control group T0 exhibiting the most substantial decrease (339.09 ± 3.44 mg Trolox/100 mL). On the other hand, the T9 group demonstrated the smallest decrease percentage, with a value of 573.48 ± 2.29 mg Trolox/100 mL.

3.3. Impact of different treatments on reducing power

Table 5 illustrates the alterations in the reducing power of juice blends subjected to various processing techniques. At day 0, the reducing power of the control group T0, which did not undergo any processing technique, was the lowest at 41.01 ± 1.59 mg AAE/100 mL. At 0 day, the group treated with chemical preservation (KMS 0.5, 1 & 1.5 %), specifically T3 with 1.5 % KMS, exhibited the highest reducing power of 43.07 ± 0.43 mg AAE/100 mL compared to the T2 and T1 groups. The group that received the HTST treatment for 5 sec (T4) showed the highest reducing power among the HTST groups (HTST 5, 10 & 21 sec) with a value of 41.02 ± 2.28 mg AAE/100 mL at day 0. The groups subjected to ultra-sonication treatments (5, 15 & 25 min) demonstrated a decrease in reducing power over a period of 21 days. The highest reducing power was exhibited by T9, with values of 48.28 ± 0.78 mg AAE/100 mL. The T0 group showed the highest decrease in reducing power (31.45 ± 1.42 mg AAE/100 mL) while the T9 group showed the lowest decrease (45.45 ± 1.92 mg AAE/100 mL).

3.4. Impact of different treatments on inhibition of DPPH radical

Table 6 presents the percentage inhibition values obtained from the DPPH assay. The ultrasound treatment T9, with a duration of 25 min, exhibited a notably higher percentage inhibition value of 34.71 ± 0.78 %, while the control group T0 displayed the lowest value of 28.77 ± 1.01 %. All treatment groups showed a percentage decrease after 7, 14, and 21 days, and the control group T0 had the highest decrease of 19.84 ± 0.98 %. The values of the treatment groups T1, T2, and T3 (KMS-0.5, 1, and 1.5 %) decreased to 22.55 ± 1.93, 24.52 ± 1.62, and 24.68 ± 0.82 %, respectively. The treatment groups T4, T5, and T6 (which underwent HTST for 5, 10, and 21 sec, respectively) exhibited decreased percentage inhibition values of 23.72 ± 0.85, 23.34 ± 1.27, and 22.34 ± 2.14 %, respectively. In contrast, the ultrasound-treated groups (T7, T8, and T9) exhibited the least decrease percentage, with values of 27.74 ± 2.61, 29.47 ± 1.92, and 32.32 ± 1.83 %, respectively.

3.5. Effects of various treatments on physicochemical properties of carrot-orange juice blends

Table 7 displays the physical and chemical characteristics of the carrot-orange juice blend after treatment with various processing techniques on day 0. The pH values of all treatment groups varied from 4.90 to 5.13, and the ^oBrix values ranged from 13.01 to 13.11. Moreover, the L* values were between 44.73 and 50.19, the a* values ranged from 19.51 to 28.45, and the b* values ranged from 31.90 to 44.12, respectively. Compared to the control group, the application of ultrasonic waves (ultrasonication) and temperature (HTST, pasteurization) were mainly responsible for the increase in TSS (^oBrix) in the carrot-orange juice blend.

3.6. GC–MS analysis results of differently treated carrot-orange juice blends

3.6.1. Alcohols

Table 8 displays the concentration of alcohols in the carrot-orange juice blends treated with various processing techniques as determined by GC–MS analysis. Analysis was performed on the three most effective treatments (T3 with KMS 1.5 %, T4 with HTST-5 sec, and T9 with US-25 min). The concentration of volatile alcohols in all treatments was dominated by 1-Pentanol, with levels ranging from 1095.78 ± 5.55 to 1324.01 ± 4.29 μg.kg⁻¹. The following most abundant volatile alcohol was 1-Octen-3-ol, with levels ranging from 576.04 ± 4.56 to 645.1 ± 5.21 μg.kg⁻¹. In contrast, β-Terpineol was the least abundant volatile alcohol, with levels ranging from 3.21 ± 0.12 to 3.90 ± 1.01 μg.kg⁻¹.

Table 8.

Volatile compounds (expressed in μg.kg⁻¹) in a carrot-orange juice blend.

Compounds	KMS (1.5 %)	HTST (5 sec)	US (25 min)
Alcohols
1-Octanol	10.59 ± 0.21c	11.66 ± 0.29b	12.35 ± 0.18a
Linalool	49.98 ± 2.31c	57.67 ± 1.91b	61.24 ± 3.22a
β-Terpineol	3.21 ± 0.12c	3.65 ± 0.99b	3.90 ± 1.01a
Terpinen-4-ol	9.02 ± 2.01c	9.95 ± 1.54b	10.82 ± 2.10a
α-Terpineol	11.47 ± 1.98b	12.03 ± 1.23ab	12.75 ± 2.21a
Carveol	4.92 ± 0.28c	5.21 ± 0.92b	5.58 ± 1.37a
Perilla Alcohol	162.87 ± 2.89c	179.76 ± 3.32b	190.4 ± 2.71a
1-Pentanol	1095.78 ± 5.55c	1245.90 ± 4.82b	1324.01 ± 4.29a
1-Octen-3-ol	576.04 ± 4.56c	607.32 ± 3.43b	645.1 ±5.21a
Furfuryl Alcohol	349.01 ± 2.49c	382.25 ± 2.91b	402.92 ± 3.35a
Aldehydes
(E)-2-Hexenal	9.75 ± 1.99a	10.12 ± 1.32a	10.65 ± 0.98a
Heptanal	578.03 ± 4.53c	604.77 ± 5.82b	643.44 ± 5.29a
3-Methylbutanal	2169.79 ± 4.38c	2489.98 ± 3.81b	2638.7 ± 5.44a
Hexanal	8571.95 ± 6.82c	9393.53 ± 4.29b	9903.43 ± 7.61a
Octanal	923.74 ± 2.33c	973.12 ± 2.98b	1031.8 ± 3.52a
(E,E)-2,4- Heptadienal	285.66 ± 1.92c	301.89 ± 2.74b	320.64 ± 2.27a
β-Cyclocitral	521.18 ± 2.39c	567.94 ± 4.85b	609.7 ± 3.55a
(E,E)-2,4 Nonadienal	210.92 ± 3.28c	234.53 ± 1.92b	249.2 ± 2.87a
Esters
Ethyl butanoate	53.29 ± 2.31c	57.96 ± 1.78b	60.89 ± 0.98a
Ethyl hexanoate	4.59 ± 1.32c	4.88 ± 0.99b	5.16 ± 0.21a
Bornyl Acetate	78.67 ± 0.91c	84.92 ± 1.77b	89.39 ± 2.05a
Geranyl Acetate	167.22 ± 1.28c	181.18 ± 2.46b	194.6 ± 2.91a
Terpenes
α-Pinene	201.55 ± 3.33c	212.98 ± 4.91b	230.88 ± 2.01a
Sabinene	99.89 ± 2.98b	105.57 ± 4.56ab	111.57 ± 5.44a
β-Myrcene	62.59 ± 1.98b	68.51 ± 2.08a	72.05 ± 2.21a
D-Limonene	1541.84 ± 5.98c	1650.90 ± 3.82b	1753.48 ± 5.12a
cis-β-Ocimene	270.79 ± 2.22c	299.58 ± 1.74b	321.91 ± 3.02a
γ-Terpinene	2.38 ± 0.12c	2.99 ± 0.49b	3.69 ± 1.01a
Terpinolene	2115.29 ± 6.82c	2225.79 ± 5.95b	2337.16 ± 5.28a
Caryophyllene	1002.56 ± 5.39c	1079.75 ± 4.87b	1159.82 ± 4.51a
α-Humulene	198.23 ± 2.58c	209.90 ± 1.93b	220.3 ± 2.05a
α- Thujene	537.82 ± 1.55c	569.01 ± 2.32b	599.2 ± 2.08a
β-Pinene	143.89 ± 2.81c	155.20 ± 1.89b	164.5 ± 3.01a
α-Phellandrene	132.28 ± 1.28c	147.79 ± 2.33b	155.4 ± 1.92a
o-Cymene	135.45 ± 2.18c	151.26 ± 1.78b	161.42 ± 2.95a
p-Cymene	91.22 ± 1.22c	97.76 ± 2.02b	103.48 ± 1.34a
Zingiberene	61.58 ± 0.99c	65.46 ± 1.05b	69.37 ± 2.30a
(Z,E)-α-Farnesene	69.21 ± 1.78b	73.47 ± 2.08ab	77.01 ± 1.39a
β-Bisabolene	97.56 ± 2.37c	109.89 ± 3.47b	116.2 ± 2.19a
(E)-γ-Bisabolene	586.14 ± 4.41c	612.91 ± 3.98b	655.11 ± 5.52a
p-Cymen-8-ol	93.78 ± 2.84c	105.87 ± 1.95b	112.49 ± 2.49a
Elemicin	1899.76 ± 6.76c	2089.67 ± 3.89b	2198.28 ± 5.28a
Myristicin	1628.21 ± 5.39c	1785.88 ± 4.42b	1936.62 ± 6.72a
Ketones
6-Methyl-5- hepten-2-one	421.94 ± 2.84c	463.82 ± 3.95b	489.9 ± 1.98a
Geranyl Acetone	376.23 ± 1.89c	405.81 ± 2.37b	428.2 ± 2.25a
Pyrazines
2,6- Dimethylpyrazine	374.13 ± 2.91c	409.99 ± 3.12b	437.27 ± 1.92a
Norizoprenoids
α-Ionone	613.89 ± 3.42c	656.92 ± 2.81b	692.8 ± 2.88a
Pyrrole
2-Acetylpyrrole	139.61 ± 1.28c	152.33 ± 3.39b	160.58 ± 2.58a
Acids
Acetic Acid	1392.51 ± 3.78c	1543.57 ± 4.19b	1634.3 ± 5.59a
Hexanoic Acid	625.77 ± 2.22c	693.18 ± 3.46b	729.99 ± 3.51a

Note: Mean values with different small letters in the same row (a–c) differ significantly (p < 0.05) from each other. While, mean values with the same letters in rows donot differ significantly.

3.6.2. Aldehydes

Table 8 presents the analysis results for the concentration of eight isolated aldehydes in the juice blends. Hexanal was found to be the most abundant aldehyde in all treatments, with concentrations ranging from 8571.95 to 9903.43 μg.kg⁻¹ and the most abundant compound among all the other compounds detected. The least abundant aldehyde identified in the analysis was (E)-2-Hexenal, with concentrations ranging from 9.75 to 10.65 μg.kg⁻¹.

3.6.3. Esters

The results of the GC–MS analysis for the concentration of esters in the juice blends are presented in Table 8. Geranyl Acetate exhibited the highest concentration of esters with a range of 167.22 ± 1.28 to 194.6 ± 2.91 μg.kg⁻¹. In contrast, Ethyl hexanoate had the lowest amount of esters with values ranging from 4.59 ± 1.32 to 5.16 ± 0.21 μg.kg⁻¹.

3.6.4. Terpenes

Table 8 shows that terpenes were the dominant group of volatile compounds detected in the analyzed juice blend. The terpenes were the most prevalent group of volatile compounds identified in the analyzed juice blend, as reported in Table 8. Terpinolene had the highest concentration among the terpenes, ranging from 2115.29 ± 6.82 to 2337.16 ± 5.28 μg.kg⁻¹. Elemicin (1899.76 ± 6.76–2198.28 ± 5.28 μg.kg⁻¹), Myristicin (1628.21 ± 5.39–1936.62 ± 6.72 μg.kg⁻¹), d-Limonene (1541.84 ± 5.98–1753.48 ± 5.12 μg.kg⁻¹), and Caryophyllene (1002.56 ± 5.39–1159.82 ± 4.51 μg.kg⁻¹) were also abundant in the blend, in that order. In contrast, γ-Terpinene was found to be the least abundant terpene, with concentrations ranging from 2.38 ± 0.12 to 3.69 ± 1.01 μg.kg⁻¹.

3.6.5. Other compounds

The findings of different volatile compound groups discovered in the juice blend, such as ketones, pyrazines, norizoprenoids, pyrroles, and acids, are presented in Table 8. Acetic acid had the highest concentration among the acid group, with values ranging from 1392.51 ± 3.78 to 1634.3 ± 5.59 μg.kg⁻¹, as observed in the various volatile compound groups in the juice blend presented in Table 8. The ketone group's compound with the highest concentration was 6-Methyl-5-hepten-2-one, with concentrations ranging from 421.94 ± 2.84 to 489.9 ± 1.98 μg.kg⁻¹, as shown in the results presented in Table 8. The compound 2,6-Dimethylpyrazine (374.13 ± 2.91–437.27 ± 1.92 μg.kg⁻¹) was found to be the most abundant in the pyrazines group, while the norizoprenoids group showed α-Ionone (613.89 ± 3.42–692.8 ± 2.88 μg.kg⁻¹). In the pyrroles group, 2-Acetylpyrrole (139.61 ± 1.28–160.58 ± 2.58 μg.kg⁻¹) was identified as the most abundant compound. These results are presented in Table 8.

4. Discussion

The objective of this study was to assess how different processing methods, such as pasteurization, chemical preservation, and ultra-sonication, affect the physicochemical properties, antioxidant properties, and volatile profile of a carrot-orange juice blend. The findings indicate that sonication has a beneficial effect on the juice blend's bioactive compounds, antioxidant activity, and reducing power when compared to the chemical preservation method. The rise in soluble solids might be attributed to the increased extraction efficiency, which is likely due to the mass transfer effects created during the acoustic cavitation process, as demonstrated in several studies [28], [29]. The application of sonication can cause physical effects such as the generation of shear and shock waves that may harm fruit tissues and cell walls. This can result in the penetration of water into the fruit cells and ultimately lead to the solubilization of a higher number of soluble solids [30]. However, it was observed that the total soluble solids of apple-carrot juice blends treated with ultrasound decreased as the storage time increased, as reported in a previous study [31]. This decrease may be attributed to sugar fermentation, which has also been observed in studies on apricot juice blends preserved with sodium benzoate [32].

Phenolic compounds are known to have significant health benefits and are typically either bound to pectin, hemicellulose, and cellulose or found in a soluble form in the vacuole [33]. The study findings suggest that a rise in sonication duration is linked to an increase in the amount of total phenolic and flavonoid content, as well as DPPH scavenging activity and reducing the power of carrot-orange juice blends. This rise in total phenols and flavonoids has significant health benefits since phenolic compounds are known for their potent antioxidant properties that can help prevent diseases [34]. Studies on blueberry juice [29], purple cactus pear juice [35], lime juice [36], and mango [37], have reported similar findings, indicating that sonication can increase total phenolic and other bioactive contents. Ultrasound may enhance the extraction of bioactive compounds, such as polyphenols, from the cell wall by inducing cavitation and thus improving mass transfer around colloidal particles. This release of polyphenols, which are linked to antioxidant activity, may contribute to the overall increase in antioxidant activity of the juice blend after sonication. Furthermore, ultrasound may also have an inhibitory effect on enzymes, including polyphenol oxidases, that could lead to enzymatic browning and a decrease in antioxidant properties. Previous studies have reported similar findings of improved antioxidant activity in sonicated juices [36], [38].

The ability to scavenge free radicals in food is an essential property since it is closely related to the health of consumers. The DPPH radical scavenging method is a simple and efficient way to measure the antioxidant capacity of food. Previous studies have shown that sonication can improve the radical scavenging activity in blueberry juice, which is associated with a positive and significant correlation between the values of total phenolic, total flavonoids, and DPPH activity [29]. Longer sonication times may facilitate the entrance of additional antioxidants into the solution, resulting in the scavenging of more free radicals. Another means of assessing potential antioxidant activity is by evaluating a compound's reductive capacity. In this assay, the presence of antioxidants in the extract may cause the reduction of the ferricyanide complex to the ferrocyanide complex. The findings show that sonication heightened the reducing power of the juice blend, whereas chemical preservation did not show any beneficial impact on the juice's nutrient content. The results of the current study are similar to the findings of Santhirasegaram et al. [35], who observed an increase in the reducing power of Chokanan mango following sonication.

Wong et al. [39] attributed the increase in tannin and most functional food parameters observed in sonication treatment to the non-thermal behavior of the process. On the other hand, raising the temperature during ultrasound treatment from 40 to 60 °C caused a greater reduction in polyphenolic compounds in the samples. However, the reduction in polyphenolic compounds was still less compared to that observed in heat treatment. Rawson et al. [40] reported in their study that an increase in treatment temperature led to a decrease in the TPC of thermosonicated watermelon juice. However, the use of thermosonication at 60 °C retained higher amounts of total polyphenols, flavonoids, and tannins compared to heat treatment.

There was no significant difference in the TSS content of freshly prepared carrot-orange juice, and the juice blends treated with ultrasonication, HHP, and pasteurization. The measurement of color is considered a reliable quality control method for carrot-orange juice blends, as it is an important parameter in determining their quality [41]. According to Rawson et al. [40], the L* and a* values of watermelon juice treated with thermosonication increased significantly at temperatures of 35 and 45 °C. This increase was attributed to the precipitation of unstable particles suspended in the juice. Conversely, the reduction in these properties following thermal treatment was in line with prior research [42], [43]. The alterations in color of fruit juices induced by sonication were ascribed to the cavitation that occurred during the process [44], [45]. As compared to untreated samples, ultrasound treated pumpkin juice showed less detrimental effect on cloud value, carotenoid content, color attributes, and distribution of particle size during the storage interval (8 to 12 days) [46]. However, Tiwari et al. [47] reported non-significant effect of sonication on acidity and ^oBrix content of orange juice when stored for a period of thirty days. On the other hand, cloud value, ascorbic acid, pH, and color attributes of orange juice were affected significantly during the storage interval. They were of the view that sonication enhanced the content of ascorbic acid during storage intervals [47]. During storage interval of 12 weeks, as compared to non-thermal processing technique, thermal pasteurization of strawberry puree resulted in loss of phenolic content (28 %), anthocyanins (54 %), and complete loss of vitamin C content [48].

In comparison to pasteurization, microwave-assisted, ultra-sonication, and high-pressure processing techniques exhibit higher efficacy in preserving aromatic compounds and promoting the conversion of aldehydes, alcohols, and terpenes to esters, thus enhancing the overall aromatic profile. The elevated heat applied during pasteurization can deactivate relevant enzymes, hinder the release of volatile components, and result in the deprivation of various substances such as thiamine, sugars, amino acids, unsaturated fatty acids, ascorbic acids, and carotenoids in citrus juice. The catalytic effect of terpenes and acids leads to the hydration reaction, which increases the alcohol content [49], [50]. However, it should be noted that not all reaction products have a positive impact on the aroma of citrus juice. The activity of enzymes can be affected by the US treatment, leading to the release of bonded aroma components, and resulting in aroma changes to some extent [45]. The use of ultrasonic treatment not only enhanced the levels of carvone and α-terpineol, which are precisely the off-flavor compounds in citrus juice, but it also enhanced the conversion of aldehydes and alcohol to esters, leading to the overall improvement in the aroma of citrus juice. By combining ultrasound and microwave assisted treatment, sterilization and enzyme passivation effects can be achieved for orange juice, without producing off-flavor compounds due to elevated temperature. The flavor profile is significantly superior to that of traditional pasteurization, according to a study conducted by Samani et al. [51]. Combining the US with hydrostatic treatment and heat can result in optimum anti-bacterial and enzyme-inhibitory effects on citrus juice. MW does not overheat the citrus juice and has an inadequate influence on the enzyme’s structure and aromatic constituents, unlike pasteurization [52]. Although high pressure does not have a direct effect on the contents of volatile compounds present in citrus juice, it can indirectly alter the content of some aroma components by enhancing or weakening enzymatic reactions, which may lead to the destruction of the balance of the overall flavor. Although high pressure does not have a direct effect on the structure of aroma components in citrus juice, it can indirectly alter the content of some aroma components by either enhancing or weakening the enzymatic reaction, which can result in an imbalance in the overall flavor. The treated samples showed a decrease in 17 types of aroma components and an increase in 15 new types of aroma components when compared to fresh orange juice. According to Pan et al. [53], the total content of esters, alcohols, and hydrocarbons showed relatively less change, while the content of aldehydes increased more than three times, and there was no significant change in the content of other components. Elevated temperature in pasteurization results in inactivation of enzyme, which affected the release of aromatic constituents and may cause degradation of thiamine, amino acids, carotenoids, sugars, and ascorbic acid. This results in promoting of hydration reaction that is catalyzed by acids, and terpenes, therefore elevating the alcohol concentration [54]. In citrus juices, ultrasonication promotes the conversion of aldehydes and alcohols to esters, hence enhanced the overall sensorial profile and aromatic compounds. Further, ultrasonication treatment prevents production of off-flavors that may be generated due to overheating during thermal treatment. Hence, as compared to pasteurization, the overall sensory profile and flavor characteristics are enhanced in ultrasonication treatments [51].

5. Conclusions

This study showed that ultrasonic treatment of carrot-orange juice blends led to an increase in functional properties such as total phenolic and flavonoid content, DPPH scavenging activity, and reduced power. The increase in these bioactive compounds was attributed to the release of bound polyphenols and the inactivation of enzymes responsible for browning. The sonication process also improved the color of the juice blends. However, the effect of sonication during storage needs further investigation. Overall, ultrasonic treatment is a promising method to enhance the functional properties of fruit juice blends.

CRediT authorship contribution statement

Anees Ahmed Khalil: Formal analysis, Methodology, Writing – original draft. Ammar Ahmad Khan: Investigation, Data curation, Writing – review & editing. Ahood Khalid: Data curation, Writing – original draft, Writing – review & editing. Zoya Abid: Data curation, Writing – review & editing. Charalampos Proestos: Supervision, Methodology, Funding acquisition, Writing – review & editing. Zuhaib F. Bhat: Writing – review & editing. Muhammad Umar Shahbaz: Writing – review & editing. Rana Muhammad Aadil: Supervision, Methodology, Writing – review & editing.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability

Data will be made available on request.