**7. Processing of beetroot and effects of processing on its biologically active components**

The use of beetroots as food has been studied by many researchers and the food industry alike due to the specific effect of color, taste and nutrients. Beetroots are consumed worldwide, even in Eastern Europe, beetroot soup is popular, while in South America, pickled beets are a traditional dish [13].

Utilization and processing possibilities of beetroots:


#### *Red Beetroot (*Beta Vulgaris *L.) DOI: http://dx.doi.org/10.5772/intechopen.106692*


Cylindrical beetroot is made into sliced, while round beetroot is made into a risky product. As a baby beetroot, the round varieties are preserved. In several European countries, soups and salads are made from the young leaves of beetroots [6]. Due to its high antioxidant content, it is used in the manufacture of several preparations in addition to canned products. Beetroot juice is appearing as a product of more and more manufacturing companies, which is also available in a version made from organic vegetables [78].

In order to preserve the bioactive active ingredients of beetroot as efficiently as possible, producers shall endeavor to give priority to humane technologies, e.g. vacuum technologies, PEF or HHP treatment.

High hydrostatic pressure (HHP) technology allows microorganisms to be gently removed from beet juice, thus prolonging their shelf life by inactivating pathogenic microorganisms. Betaxanthins in beetroot juice were more stable than betacyanins under high pressure. Losses of betalain pigments under high hydrostatic pressure at ambient temperature were small compared to heat treatment. The significant reduction in the number of spoilage and pathogenic microorganisms without the recovery of sublethal-damaged cells and the slight degradation of pigments indicate the possibility of industrial application of high pressure to preserve beetroot juice [79].

One of the best ways to preserve fruits and vegetables is drying. In the case of vegetables, conventional convective drying was the most common; due to its simplicity, economical design and operation costs, however, this method of drying can greatly reduce the content values of vegetables [68].

In an experiment conducted by MALAKAR et al. [80], betalain pigment retention was 63.98% higher for drying with an evacuated tubular solar dryer (ETSD) than for day drying. The color changes were higher when dried in the sun. The mean phenol content and antioxidant capacities were 31.07% and 21.87% higher in ETSD, respectively than in the sun-dried. Therefore, ETSD can efficiently dry other foods with reduced drying time and significant preservation of quality characteristics.

According to a study by MELLA et al. [81], vacuum drying (VD) can be a suitable alternative to freeze-drying (FD). The effect of both drying techniques on the physicochemical properties, betalain pigment, antioxidant potential, and individual phenolic compounds of beetroots have been studied. The results showed that the increase in temperature promotes growth in the drying rate and effectively shortens the drying time. In general, VD samples retained the approximate composition of beets better than FD. Nevertheless, VD (50° C) excels in FD in terms of total polyphenol content (TPC) and oxygen radical absorption capacity (ORAC). In addition, syringic acid was identified in the VD samples at 50° C but not in the FD samples.

Kazimierczak et al. [29] found that beetroots and fermented beetroot juices from organic farming contained more vitamin C than conventional ones. The results reveal that organic and conventionally produced beetroots and fermented beetroot juice have different chemical properties and different effects on cancer cells. During the lactic fermentation of beetroot juices, 75% of betacyanins were retained compared

to their original concentration. By adjusting the pH to about 4, this process also promotes antioxidant activity and avoids the negative effects of heat treatment, which reduces antioxidant content.

Beetroots are suitable as a substitute for synthetic colorants [58] and can thus become a marketing tool in the food industry [82]. This is because synthetic colorants can have negative effects on human health, cause allergies, and long-term consumption can be carcinogenic [83]. Dried and concentrated beetroot juice is also used in many foods to increase the intensity of the red color. Examples of such products are ice creams, jams, desserts, tomato concentrates, beverages, and dairy products [84]. Fresh beetroots, beetroot powder, or extracted pigments are used in soups, sauces, confectionery, ice creams, and breakfast cereals [68, 85]. The choice depends largely on the manufacturing technology, not only on the state of the excipient but also on its heat sensitivity. When exposed to heat, it changes color to brown [86], but it still occurs in heat-treated and then refrigerated beverages, desserts, ice creams, dairy products, and confectionery [87].

Processing methods have a significant effect on antioxidant activity and the availability of its phytochemicals. Some processing methods, such as microwave vacuum drying, fermentation, and irradiation, enhance antioxidant capacity and pigment stabilization, while convective drying reduces color retention [88, 89]. VASCONCELLOS et al. [40] examined the total antioxidant activity of beetroot chips (95.70%), beetroot powder (95.31%), boiled beetroots (85.79%), and beetroot juice (80.48%). According to their results, there was no significant difference between the antioxidant activity of beetroot chips and beetroot powder, and higher values were detected in them than in cooked beetroot and beetroot juice. The liquid chromatography method developed by PIETRZKOWSKI and THRESHER [90] was able to increase the betalain content of the beetroot powder by passing the beetroot juice through a silica gel column before drying. Thus, a concentration of up to 45% w/w betalain is achieved. NEMZER et al. [26] found that the higher betalain content of beetroot powder produced with this new technology is 615 mg/100 g of vitamin C, while the value of beetroot powder produced by the traditional method in an oven is only 1−7 mg/100 g.

Factors, that affect the stability of antioxidants or betalains, are storage, pH, temperature, water activity, oxygen, metals, and ion radiation [29, 91]. Optimal stability of betalains is achieved in the pH range of 3−7, suggesting that it is worth using in acidic food preparations. Thus, betalains are stable in foods with a pH 5, even in products below pH 3 the color of betanin changes to violet, and above pH 7 to blue color due to the longer wavelength [91]. Betanin is degraded in an alkaline environment, hydrolysis of aldimine to form ferulic acid with an amino group. The degradation of betanin at pH 3 is three times higher than at pH 5 under fluorescent light. Betalain was found to be more stable between pH 5.5 and 5.8 in the presence of oxygen. Under anaerobic conditions, betalain is more stable at pH 4−5 [92–94].

Water activity regulates the rate of biochemical conversion and influences the stability of betanin by regulating the water-dependent hydrolytic reaction of aldimine bond cleavage. A decrease in water activity (below 0.63) during various treatment procedures, such as drying and evaporation, enhances the stability of betalains [95]. An increase in water activity raises the rate of betalain degradation from 0.32 to 0.75. However, in the case of encapsulated beetroot pigment, the greatest degradation of betanin occurs at a water activity value of 0.64 [96].

Temperature also affects the stability of betalains. An increase in temperature results in degradation of betalain. However, thermal decomposition is also affected by temperature range, degree of heating, presence of oxygen, and pigment concentration [97].

*Red Beetroot (*Beta Vulgaris *L.) DOI: http://dx.doi.org/10.5772/intechopen.106692*

Colorants are oxidized and degraded in the presence of light. There is an inverse relationship between light intensity in the range of 2200−−4400 lux and the stability of betalain. Absorption of ultraviolet and visible light excites the chromophore electrons of betalain, which induces higher reactivity or lower molecular activation energy. However, the effect of light under anaerobic conditions is negligible [92–94].

Some metal cations have been identified that promote or accelerate the degradation of betanin, such as iron, copper, tin, aluminum, and so on. According to a study, beetroot juice is less sensitive to metal ions because it contains metal complexing agents. Chelating agents (citric acid and EDTA) have been shown to stabilize betanin against metal-catalyzed degradation [92–94].
