Iranian Food Science and Technology Research Journal

Abstract Introduction 
The first quality attribute about food evaluated by consumer is visual characteristics. The apparent attributes of a product include its shape, color, packaging, size, and uniformity. The consumer considers the product's appearance in the first step before any other information about other characteristics, such as taste or smell, especially in the first purchase. Color is the most crucial indicator of the quality of food that affects consumer acceptance. To replace the color lost during the process, increasing the existing color and minimizing variation during processing; natural colors, synthetic and inorganic colorants are added to food. Red beet is one of the most important natural sources of color; the essential pigment in this plant is betalain, composed of two subunits, betacyanin, and betaxantine. Considering the growing demand to develop more effective methods for extracting active compounds present in vegetable materials, including naturally occurring betalain and other nutritious compounds, this research was conducted to optimize the extraction conditions of this pigment from red beet.
 
Materials and Methods 
Preparation of red beet 
The red beets were washed, peeled, and grated to prepare the sample. Then, red beets were dried in an oven at 30 °C for 48 hours and milled. For extraction, 10 grams of red beet powder was mixed with 200 ml of solvent (water-ethanol in a ratio of 1:1) and subjected to ultrasonication at 37 kHz. Experiments in 27 runs were performed based on a historical data design, randomized subtype and quadratic model. After the implementation with the edition of Design Expert 7 software, the range of variables pH (3-5), temperature (15-25 °C), and time (10-20 min) were applied for extraction. The pulp was dried using a Wattman filter paper in an oven at 35 °C and used for subsequent tests. 
 
Yield measurements 
The efficiency of the extraction process was calculated by dividing the weight of the extract obtained by the weight of the beetroot. 
 
Measurement of pigments 
The betacyanin and betaxanthine pigments show maximum absorption in 522-559 nm and 474-480 nm, respectively. To measure betacyanin and betaxanthine in extracts, a certain amount of powder was dissolved in distilled water, and its absorbance was measured at  530 and 480 nm. The amount of pigments obtained from different extraction conditions was compared.
 
 
Results and Discussion  
In this study, the overall results showed that an increase in the extraction pH and time increased the extraction of betacyanine and betaxanthine. It would be better to extract betacyanine at temperatures below 25 °C since this pigment is sensitive to high temperatures. The maximum yield was observed when pH value, temperature, and time were 5, 21 °C, and 20 min, respectively. Comparison of experimental and predicted values of the proposed responses at the proposed optimal points by t-test showed no significant difference (p<0.05). A quadratic model was suggested for the responses, and the lack of fit was not significant (p<0.05). The extraction of betaline from red beet using the ultrasonic assisted method causes a reduction in time, temperature, energy, and solvent consumption.
 
Conclusion
The maximum yield was observed when pH value, temperature, and time were 5, 21 °C, and 20 min, respectively. Comparison of experimental and predicted values of the optimal points showed no significant difference by t-test (p<0.05). According to the results obtained from this research, ultrasonic assisted extraction can be considered an efficient and fast method. Extraction of betalain from red beetroot with ultrasonic assisted method is more efficient. It can replace the regular practice of extraction in the industry due to the reduction of time, temperature, energy, and solvent consumption, thus reducing cost and increasing profit.

Abstract Introduction
Today, carrots are widely used in freshly cut products, including ready to eat salads, however, its shelf life is reduced due to the damage caused on the texture of the product which accelerate the reduction of nutritional value as well as the growth of microorganisms, (Azizian et al., 2020). To increase the shelf life of freshly cut products, it is recommended to use coatings on the surface of these products. Alginate is a hydrophilic biopolymer and having unique colloidal characteristics, it demonstrates a suitable coating function. Olivas et al. (2008) showed that by coating fresh apple slices with alginate and antimicrobial agents increased the shelf life of apple and decreased weight loss. Among the native plants of Iran, we can mention the Oliveria plant, which belongs to the Amblifra family. The aerial parts of this plant have a significant amount of essential oils (EOs). Researches by Amin et al. (2005) on the antimicrobial properties of Oliveria essential oils have shown a broad-spectrum antimicrobial activity against all studied organisms, and this effect is comparable to that of commercial antibiotics. Packaging with modified atmosphere is one of the best ways to increase the shelf life of fruits and vegetables. The purpose of this study was to investigate the effect of alginate and Oliveria essential oils on the physicochemical and microbial characteristics of grated carrots in polypropylene packages with modified atmosphere during storage.
 
Methods
Essential oil of Oliveria plant was extracted, dehydrated by sodium sulfate and placed in sealed glass container and stored at 4˚C until using. Carrots prepared from Wilmoren cultivar. An industrial crusher crushed the carrots, and samples were coated by treatment solutions. Two treatments of coating were prepared, one as control with 0% and the other one with 1.5% alginate with stirring and moderate heat (50-60°C) (Lu et al., 2009). Then the Oliveria EO was added to the alginate solution at the specified concentration. The resulting solution was deaerated at 25˚C.
T1: control sample (without coating)
T2: 1.5% alginate
T3: 150 ppm Olivieria EO
T4: 250 ppm Olivieria EO
T5: 1.5% alginate and 150 ppm of Olivieria EO
T6: 1.5% alginate and 250 ppm of Olivieria EO
After weighing (250 g), the grated carrots (control and coated) were placed in 10 g polypropylene packages of suitable food grade in dimensions of 50 × 190 × 144 cm and the package was injected with 5% O₂, 5% CO₂ and 90% N₂. The packages were then stored in the refrigerator for 12 days at 4±1˚C. All experiments were performed on days 1, 3, 6, 9, and 12.
 
Evaluation of Chemical, Microbial and Sensory Characteristics
A pH meter used for pH determination (Rad et al., 2020). The acidity measured based on Rocha et al. (2007) method.
The weight was reported using pre and post-storage weight. The carotenoid concentration calculated by Rocha et al. (2007) method. Total soluble solids determined by refractometer (Rad et al., 2020). Ascorbic acid content measured by Falahi et al. (2013) method. The L*, a*, b* and WI (white index) indicators of grated carrots evaluated by Hunter lab system. A 5-point hedonic test was used to assess sensory attributes(Ajnevardi et al., 2002). The internal gas concentration evaluated by Ullsten & Hedenqvist (2003) method. Total count microorganisms, mold, and yeast were counted according to the method of Azizian et al. (2020).
 
Data Analysis
This study was conducted in a completely randomized design with factorial form to investigate the effect of independent variables of type of alginate coating (2 levels), essential oil (3 levels) and time (5 levels) on the physicochemical properties of grated carrots (3 replications) and total counting, mold and yeast (2 replications). Mean comparison was performed using LSD test at 5% probability level and SPSS software was used to statistically analyze data.
 
Result
The results showed that the level of acidity, carotenoid and acid ascorbic, the amount of L* and sensory (color, quality, flavor, odor) scores reduced during time. By contrast the level of pH, weight loss, the amount of a*, b*, CO₂, TSS and total counts increased (P<0.05). Also, with increasing the concentration of essential oils and alginates, the amount of acidity, carotenoids, ascorbic acid, L* increased and pH, weight loss, TSS, a*, b*, CO₂ and total count decreased (P<0.05). Escherichia coli, mold and yeast count of the samples did not show any growth from the mentioned treatments until the 12^th day. Overall, the Oliveria essential oil and alginate were effective in improving the properties of grated carrots under the modified atmosphere during storage.
 
Conclusion
The study showed that Oliveria EO and alginate added to grated carrots in modified atmosphere packaging during storage was effective in reducing respiration, water loss, microbial load and increased the shelf life. Treatment containing 1.5% alginate and 250 ppm Oliveria EO showed the best chemical, microbial and sensory characteristics. The results indicated that by packing under modified atmosphere and coating by alginate and Oliveria EO, a new carrot product provided to the market with maintaining durability and quality characteristics during storage.