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20Fermented Red Beet Juice

Zsolt Zaln, Anna Halsz, and gnes Barth

20.1 Introduction

Red beet (Beta vulgaris, also known as beetroot, table beet, garden beet, or blood turnip) is a popular veg-etable all over the world. This vegetable plant is a considerable source of vitamins C and B (B1, B2, and B6), minerals (such as calcium, iron, potassium, magnesium, phosphorus), and moreover, it contains a relatively high level of folic acid (Wang and Goldman 1997; Vli et al. 2007; Srdi et al. 2009). However, the most important bioactive agents of the red beet are the water-soluble plant pigments, the betalains. These nitrogen-containing pigments, which are synthesized from the amino acid tyrosine, are composed of two main groups, the red betacyanins and the yellow betaxanthins. The red beet betalains contain two major soluble pigments, the betanin (red) and the vulgaxanthine I (yellow; Azeredo 2009). Betanin is the main coloring component present in the food color additive, E-162. Although the tops of the red beet plant can be cooked or served fresh as greens, the root is the most valuable part of the plant, which may be eaten fresh or pickled for salads or cooked whole, then sliced or diced, and moreover, it can be consumed as a juice or in fermented form.

The fermentation of vegetables is an ancient practice that has been applied by Asian and Mediterranean people for the past 4000 years (Hulse 2004). The original purpose for the fermentation of raw materials was to preserve it, and this was accomplished with naturally occurring fermentations because the ancient people were not aware of the role of the microorganisms in this process. The knowledge and the method-ologies of the production of ancient fermented foods were handed down from generation to generation. Nevertheless, this preservation process, and the fermented vegetables themselves, have spread all over the world and after millennia they could be found among our meals; for example, sauerkraut and olives from the Western World, gari from West-Africa, kimchi from Korea, gundruk from Nepal, or sunki from Japan. The lactic acid bacteria (LAB) not only preserves the raw material, but also makes some plant material more digestible, thus improving the nutritional properties of the food and moreover developing the flavor and aroma, creating a higher value product.

Fermentation depends considerably on the biological activity of microorganisms. The raw material (veg-etables) provides the substrate for the LAB, which excrete a range of microbial metabolites; therefore, both

CONTENTS

20.1 Introduction .................................................................................................................................. 37320.2 Starter Culture Selection .............................................................................................................. 374

20.2.1 Biogenic Amine Production ............................................................................................ 37520.2.2 Growth and Acidification ................................................................................................ 37520.2.3 Hydrogen Peroxide Production ........................................................................................ 37720.2.4 Antimicrobial Activity .................................................................................................... 37720.2.5 Changes in Betalains ....................................................................................................... 37920.2.6 Viability ........................................................................................................................... 379

20.3 The Process of Fermentation ....................................................................................................... 37920.4 Health Benefits of Fermented Products ....................................................................................... 38020.5 Concluding Remarks .................................................................................................................... 381References .............................................................................................................................................. 381

374 Handbook of Plant-Based Fermented Food and Beverage Technology

the type of substrate and the genera of bacteria and their enzyme activity considerably influence the quality of the end product. LAB could produce energy for their activity or for propagation through lactofermenta-tion. The uptaken or intracellularly hydrolyzed carbohydrates can be fermented by lactobacillus strains through two major pathways: glycolysis (EmbdenMeyerhof pathway) is used by the homofermentative LAB, and the 6-phosphogluconate/phosphoketolase pathway is used by heterofermentative LAB. During the fermentation of carbohydrate, when the sugars are converted to cellular energy, LAB excrete lactate as a metabolic by-product. Generally, lactic acid is the predominant end product (always by the obligate homofermentative strains), but under various conditions, the amount of other by-products (acetic and other acids, alcohol, and carbon dioxide) could be increased by the facultative homofermentative strains, whereas the obligate heterofermentative strains always produce significant amounts of by-product, other than lactic acid. The acids produced play an important role in the preservation of the product as well as enhancing the shelf life and microbiological safety of the fermented food. Aside from organic acids (lactic, acetic, formic, caproic, propionic, butyric, and valeric acids), LAB can produce several other antimicrobial components, such as hydrogen peroxide (Rodrgues et al. 1997; Ito et al. 2003), carbon dioxide, alcohol, diacetyl (Ammor et al. 2006), and proteinaceous, ribosomally synthesized antimicrobial compounds, so-called bacteriocins (Cleveland et al. 2001; Plockov et al. 2001), which also take part in the preservation as well as forming alto-gether synergistically the microbiological safety of the product. Beyond preservation, acids have remark-able effects on the organoleptical properties of the product; however, in the formation of flavor, several other metabolites play a role. Depending on the enzymes present in the bacterial strains, different flavors can develop because of the contribution of many enzymes, which lead to various flavor compounds and, in such a way, different products from the point of view of aroma. In LAB, pyruvate is a starting molecule for the formation of short-chain flavor compounds such as acetaldehyde, acetate, acetoin, diacetyl, and ethanol. Lactobacilli can also metabolize citrate to produce acetoin, acetolactate, and diacetyl (Marilley and Casey 2004). The amino acidconverting enzymes of LAB can also play an essential role in the flavor develop-ment of the product. Amino acids in the vegetable substrate may contribute to the production of such flavor and aroma compounds such as aldehydes, acids, alcohols, esters, and sulfur compounds (Ayad et al. 2001). Beyond preservation and aroma formation, LAB could also detoxify the substrate. Vegetables provide one of the main sources for nitrate and nitrite intake in human nutrition. The red beet, leafy greens, kohl-rabi, and radish are considered as highnitrate accumulation plants (Nagy-Gasztonyi et al. 2006). During fermentation, LAB can reduce or, in some cases, completely remove nitrites from the substrate (Herd-Leszczynska and Miedzobrodzka 1992; Walkowiak-Tomczak and Zieliska 2006). Many microorganisms, such as Enterobacteriaceae and certain Lactobacilli, Pediococci, and Enterococci, are particularly active in the formation of biogenic amines. The amount and type of amine formed in a food depends on the nature of the product and the microorganisms present. The lactofermented food products contain considerable amounts of putrescine, cadaverine, histamine, and tyramine (Santos 1996). Amine production of bacteria depends on the amino acid decarboxylase activity of that certain strain. Some biogenic amines are indis-pensable components of living cells; however, the consumption of foods that contain high concentrations of biogenic amines may have a toxicological effect. As this short introduction has shown, the activity and metabolite production of LAB strongly influence the quality of the product and have a great effect on the shelf life, taste, digestibility, and safety of fermented food.

Spontaneous fermentation could result in a unique product with appropriate properties; however, it is unre-peatable, the quality of the product is changing and the safety of the product is questionable because of the lack or absence of control in the process. Constant and appropriate quality is absolutely necessary for the applica-tion of a selected starter culture with good fermentation properties and low amine production.

20.2 Starter Culture Selection

For the lactofermentation of red beet, the most applicable LAB are the strains from the Lactobacillus genus because the members of this genus can be found in many different habitats, as well as on the plants and plant materials themselves, and they are already used as starter cultures for different fermented foods (cheese, meat, sourdough, etc.). Several lactobacilli strains are also regarded as probiotics and are applied in probiotic food (Stiles and Holzapfel 1997; Holzapfel and Schillinger 2002).

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20.2.1 BiogenicAmineProduction

Aside from the several positive effects of LAB in food preservation, their ability to decarboxylize amino acids and produce biogenic amines is also very important in food production. These biogenic amines may be formed and degraded during the normal metabolism of animals, plants, and microorganisms. In food, they may result either from endogenous amino acid decarboxylase activity in food materials or from the activity of decarboxylase-positive bacteria. Depending on the spoilage association (e.g., Enterobacteriaceae), microbial deterioration of food may be accompanied by an increased production of amino acid decarboxylases. Experimental data indicates a correlation between bacterial numbers and the biogenic amine content of particular foods. This has been intensely studied for fish, meat, and some veg-etables. Several authors have published data about fermented foods such as sauerkraut, cheese, sausage, beer, and wine (Stratton et al. 1991; Halsz et al. 1994, 1999a,b; Leito et al. 2000; Kalac et al. 2002; Suzzi and Gardini 2003). Concentrations of biogenic amines show extreme variations in traditional spontane-ously fermented food and beverages. Quality criteria, with respect to the presence of histamine and other biogenic amines in foods and food products, are necessary from the toxicological point of view and also from a technological aspect. There is evidence of the involvement of histamine and tyramine as causative agents in food poisoning. Because histamine has one of the highest biological activities of all amines, its production is of particular interest. From the point of view of good manufacturing practices, levels of 50 to 100, 100 to 800, and 30 mg/kg for histamine, tyramine, and -phenylethylamine, respectively, or a total of 100 to 200 mg/kg, are regarded as acceptable. Some countries have regulated the maximum amounts of specific products allowable. In Switzerland, 10 mg of histamine per liter of wine is the permissible limit; in the United States, 50 mg/100 g fish indicates a danger to health. The European Union established leg-islative limits only for histamine in fish (Maintz and Novak 2007). Amine production of bacteria depends on the amino acid decarboxylase activity of that certain strain. Halsz et al. (1994) measured histidine activity levels of 3.7 102 mol/min for Lactobacillus brevis var. lindneri, and in Lactobacillus planta-rum, it was 7.6 102 mol/min. The highest activities were detected in the stationary growth phase. This result is in agreement with the findings of Knsch et al. (1990), who found that a significant accumulation of histamine and tyramine only occurred in the final period of sauerkraut fermentation. However, as redox potential also influences histidine decarboxylase activity, conditions resulting in reduced redox potential stimulate amine formation, and histidine decarboxylase activity seems to be inactivated or destroyed in the presence of oxygen. Amine synthesis is also influenced by stress conditions. Cold-shocked Lb. plan-tarum increased amine synthesis in comparison with untreated cells (Amal Ahmed 1996). Because some people suffer adverse reactions after consuming amines, the production of fermented foods with predict-ably low levels of specific amines needs to be addressed by the food industry. It is possible to select starter culture strains with low amine production, no histamine synthesis, and reduced tyramine secretion.

The authentic LAB must be investigated for their biogenic amine production. Aside from histamine and tyramine, the total amine synthesis also has to be considered. Only low amine producers should be considered for further selection, and should include the ability to grow on red beet as the only substrate, acid production, speed of pH reduction, and last but not least, hydrogen peroxide synthesis. Halsz et al. (1994, 1999a,b) found that the amino acid decarboxylase enzyme activity of bacteria used as starter cultures varied widely, and some of them even produce histamine (Table 20.1). Despite this, the biogenic amine contents of spontaneously fermented samples were compared with a potential starter culture fermented red beet; in the spontaneously fermented sample, the amount of total biogenic amine was five to seven times greater and histamine level contents were also detected (Table 20.2). This demonstrates that the application of a well-chosen starter culture is preferable to spontaneous fermentation.

20.2.2 GrowthandAcidification

One of the most important properties of a starter culture is fast growth on the raw material to quickly reach an appropriately high cell count. The cells of starter cultures with fast growth, on the one hand, compete with the other coexisting microbes for substrates and a niche and, on the other hand, remove fermentable carbohydrates from the raw material; in this way, preventing the growth of other microbes. At the same time, during its growth, the starter culture produces several metabolic end products from

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which the greatest amount of organic acids are produced. These acids, during the fast-growing phase, cause quick acidification and therefore the decrease in pH is another good sign of the process of fermen-tation. The low pH and the undissociated organic acids also have an inhibitory effect on many organisms. According to our results, the Lactobacillus strains grow well on red beet juice. From the initial 106CFU/mL level, the viable cell count reached 1.6 to 4.3 108 CFU/mL during 32 hours at 30C (Barth etal. 2004). Other authors reported that the cell count of lactobacilli could even reach 109 CFU/mL after 48 hours of fermentation at 30C (Yoon et al. 2005), 9.48 log CFU/mL on sliced red beet at 20C after 4days (Walkowiak-Tomczak and Zieliska 2006), and 10.7 log CFU/mL in juice after 8 hours of incu-bation at 37C if the initial cell count is high enough (8.71 log CFU/mL, according to Buruleanu et al. 2009); however, in this case, a rapid cell count decrease could then be observed. It can be established that the type of substrate (chopped red beet or juice) and the Lactobacillus strains used only slightly influ-ence the reachable cell count, rather the parameters of the incubation significantly influence the final cell number. In contradistinction to this, the pH changes not only according to the strain but also the variety of the red beet (Table 20.3). The pH decrease depends considerably on the acid production (the enzyme activity of the cells). The different qualities and quantities of the acids produced could cause different decreases in the pH of the environment, even at the same cell count. Thus, in the metabolic pathways, the fermentation profile of the strain plays an important role in acidification. The decrease in pH was faster in every case in which starter cultures were applied compared with the spontaneously fermented samples. The pH of the fermented juice decreased from the initial values of 5.5 to lower than 4 at 24 hours of fermentation. Yoon et al. (2005) reported the same results when the pH decreased to less than 4.5 from the initial 6.3 after 48 hours. Because rapid acidification is essential for the microbial stability of the product, for the selection of the starter culture, this property of the strain is very important. Aside from the low pH, the remaining undissociated weak acids also have an antimicrobial effect, an effect which could be increased by the production of hydrogen peroxide.

TABLE20.2

Biogenic Amine Content in the Spontaneously and with a Starter Culture Fermented Product (g amine/mL brine)

Strains

Biogenic Amines

PUT HIST CAD SPD AGM SPER TYRM Lb. plantarum 0.89 ND ND 5.10 4.49 6.10 ND 16.58

Lb. brevis var. lindneri 7.22 ND 0.49 6.14 4.40 6.11 ND 24.36

Spontaneous fermentation 6.42 3.22 29.38 7.01 14.17 5.17 60.04 125.51

Source: Halsz, A. and Z. Zaln, Akadmiai Kiado, 7185, 2009. With permission.

TABLE20.1

Biogenic Amine Production of Selected Strains (g/mL)

Strain

Biogenic Amines, Produced in MRS

PUT HIST CAD SPED AGM SPER TYRM Lb. fermentum DT 41 0.50 TR TR 1.45 0.10 0.60 1.85 4.50

Lb. acidophilus N2 TR TR TR 2.83 ND ND 3.42 6.25

Lb. plantarum 2142 TR ND TR 0.45 ND 0.38 0.54 1.37

Lb. casei-casei 2750 0.22 ND 0.19 0.14 TR 0.25 0.56 1.36

Lb. casei-casei 2752 TR ND TR 0.26 ND 0.20 0.98 1.44

Lb. curvatus 2770 0.70 ND TR 0.33 0.38 0.67 6.20 8.28

Lb. curvatus 2775 0.26 ND TR 0.30 0.3 0.78 6.43 8.2

Lb. plantarum 2739 0.52 0.20 0.86 1.40 1.78 0.90 12.74 18.40

Source: Halsz, A. and Z. Zaln, Akadmiai Kiado, 7185, 2009. With permission.

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20.2.3 HydrogenPeroxideProduction

Lactobacilli are able to generate hydrogen peroxide in the presence of oxygen by flavoprotein oxidase, nic-otinamide adenine dinucleotide (NADH) oxidase, and pyruvate oxidase, which then accumulates because of the lack of catalase in lactobacilli (Murphy and Condon 1984). Hydrogen peroxide is a strong oxidiz-ing agent and thus is a well-known antibacterial component (Ouwehand 1998; Ito et al. 2003). However, it only possesses short-lived action because hydrogen peroxide reacts with the organic material of the environment. This oxidizing effect can cause bleaching of colored components of red beet and, in this way, causes undesired loss of the color of the product aside from the degradation of the antioxidant com-ponents. Betalains, the biologically active pigments of red beet, are also sensitive to the oxidative effect of hydrogen peroxide (Wasserman et al. 1984). Because of this, the starter strains for red beet juice fermenta-tion should not form hydrogen peroxide or only at low concentrations. The difference in the production of hydrogen peroxide between the spontaneous and starter culture fermentations is significant (Table 20.4).

20.2.4 AntimicrobialActivity

The original purpose of fermentation was the preservation of the raw material. The growth and antimicrobial activity of the starter culture plays the greatest role in this preservation effect. The best starter cultures have a wide antimicrobial activity against spoilage bacteria, yeasts, and molds. This activity is very important because the surface of the raw material contains a wide range of microbes. According to our investigations, 2.3 107 to 7.5 108 CFU live cells, 0.9 to 9.3 102 CFU coliforms, and 1.7 105 to 3.4 106 CFU molds and yeasts, and also Enterobacteriaceae can be found on the surface of different varieties of red beet. Walkowiak-Tomczak and Zieliska (2006) found 2.07 log CFU/g of mesophilic bacteria on fresh red beet root and, in some cases, 1.52 log CFU/g of molds and yeasts. The number of microbes on the surface of red beets is influenced by several external parameters such as the cropland, the weather, and we have even obtained slight differences between varieties of red beet. Nevertheless, these microbes can contaminate the prepared red beet raw material. Klewicka et al. (2004) reported mesophilic bacteria at a concentration of 103 CFU/mL, as well as yeasts and molds in small quantities in fresh beet juice. LAB are able to inhibit the growth of many pathogens and food spoilage microorganisms, such as Escherichia coli, Listeria monocytogenes, Salmonella enteritidis, and molds (Harris et al. 1989; Schillinger et al. 1991; Corsetti et al. 1998; Park et al. 2005). According to our investigations, the potential starter cultures show various inhibitory activities against food-borne microorgan-isms (Table 20.5). However, some strains, which have a relatively broad inhibitory activity against bacteria and molds can also be found (Hudek et al. 2007).

TABLE20.3

pH Drop in Fermented Red Beet after 24 Hours

Beet Variety

LAB Strains

ControlLb.plantarum2142 Lb.curvatus 2770 Lb.casei-casei2745

Bonel 3.85 3.64 3.82 5.45

Bolivar 3.90 3.15 3.87 5.55

Pablo 3.70 3.62 3.72 5.32

Source: Halsz, A. and Z. Zaln, Akadmiai Kiado, 7185, 2009. With permission.

TABLE20.4

Hydrogen Peroxide Production of LAB on Red Beet

Incubation Time (hours)

2 24 48 72

Spontaneous 2.07 1.93 1.79 1.63

Lb. plantarum 2142 0.34 0.34 0.33 0.33

Lb. curvatus 2770 0.58 0.51 0.60 0.57

Source: Halsz, A. and Z. Zaln, Akadmiai Kiado, 7185, 2009. With permission.

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TABLE20.5

Antimicrobial Spectrum of Some Potential Starter Lactobacillus Strains

Indicator Microorganism

Sign of Strain

Antimicrobial Activity

Lb.fermentum DT41

Lb.acidophilus N2

Lb.plantarum2739

Lb.plantarum2142

Lb.casei-casei2750

Lb.casei-casei 2752

Lb.curvatus 2770

Lb.curvatus2775

Listeria innocua DSM 2257

+ +

Staphylococcus aureus ATTC 14438

Enterobacter

Enterobacter 10 + + + +

Bacillus + E. coli 2 + + + +

Pseudomonas + + + + +Pseudomonas 7 + + + + +

Klebsiella oxtocoa 4 + + +

Alcaligenes 8 +

Enterococcus + + + +

Micrococcus 5 + + + + + + + +

Asp. flavus 31 +

Asp. parasiticus 1039 +

Note: , no inhibitory effect; , weak inhibitory effect; +, strong inhibitory effect.

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20.2.5 ChangesinBetalains

Because the betalains are the most important bioactive component of the red beet, the investigation of the effect of starter culture on this component is also very important. The changes in the absorbances of the red and yellow pigments unambiguously show the effects on the betalains. Investigating the absorbances at 535 and 489 nm, a great decrease could be observed in the fermented samples in comparison with the initial values (Figure 20.1). The decrease was the greatest in the spontaneously fermented (control) sample. Among the different Lactobacillus strains, no significant difference could be detected, which is in agreement with their similar hydrogen peroxide production. Betalains are also partly decolorized because of the low pH, and furthermore, the red beet has several endogenous enzymes such as polyphe-noloxidases and beetroot cell wallassociated peroxidase enzymes, which may cause the degradation of betalain and loss of color (Lashley and Wiley 1979; Azeredo 2009). These peroxidases make contact with their substrates after slicing and, as the cell wall destruction is more intensive during maceration, the decolorization is greater under optimal circumstances for peroxidase.

20.2.6 Viability

Because several lactobacilli strains are regarded as probiotics and their beneficial effects are connected with their live forms, the living cells of the starter Lactobacillus strains and their viability after fermen-tation (during storage until consumption) is also important. The strains show various viabilities, the cell counts of several strains decreased to the initial level during storage at 4C for 4 weeks, but some strains remained at 108 CFU/mL after 4 weeks (Barth et al. 2004; Yoon et al. 2005).

20.3 The Process of Fermentation

The first step in fermentation is the preparation of the raw material for inoculation with the starter culture. As previously mentioned, the surface of the harvested red beet root contains a wide range of numerous microorganisms, and thus the elimination of soil and microbes from the surface of the roots by washing is the first important step. This is followed by the peeling of the root and a repeat washing. The cleaned red beet root, after chopping, can be used directly in this form or a juice could be made from it. Heat treatment (blanching or pasteurization) can be considered before the inoculation. On the one hand, with this step, the microbial safety of the product can be increased and the chopped form will be softer, but on the other hand, the heat treatment can cause change in the color, the red-violet can turn to brown and the activity of the bioactive molecules could vanish. However, good manufacturing practicewhat is necessary during the whole processcan produce a microbiologically safe raw material without heat

4895350

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FIGURE20.1 Effect of lactofermentation on pigment components of red beet (Pablo variety). (With kind permission from Springer Science+Business Media: Eur Food Res Technol, 218, 2004, 1847, Barth, ., A. Halsz, E. Nmeth, Zs. Zaln, Fig. 1.)

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treatment. The juice can be produced both mechanically by centrifuge and enzymatically by liquefac-tion. For this enzymatic procedure, the red beet root should be mixed with the same amount of water and, after heat treatment at 80C for 2 minutes, cooled down to 40C. A macerating-type pectolytic enzyme mixture should be added to this mixture and treated at 40C for 2 hours. Then, the reaction should be stopped by heating at 80C and the mixture homogenized and the pH adjusted. For the fermentation of red beet slices, these should be filled up with brine before the inoculation. After the preparation of red beets, the next step is inoculation with the starter culture. The population of the starter culture should be at the exponential growth phase, thus culturing for one night is optimal. The amount of inoculum is usually 1% to 2% of the volume of the raw material. The initial cell concentration in the product should be at least 106 cell/mL juice/brine to guarantee fast growth and rapid acidification to keep down the other potential microbes present. The optimal incubation temperature is 30C to 37C. The optimal incubation time depends on the temperature and the initial cell concentration, but at 30C, the 106 cell/mL initial cell concentration and pH drop reaches the maximum after 32 to 48 hours.

20.4 Health Benefits of Fermented Products

Both the red beet and the potential probiotic starter culture have in themselves beneficial health effects on human consumers. Hippocrates, Galen, Avicenna, and Paracelsus have previously used red beet in the treatment of several gastrointestinal diseases, fevers, and anemia, as well as in wound healing (Srdi et al. 2009). Red beet has traditionally been used in folk medicine because it has been considered to have blood-forming and antitumor properties. The most important bioactive components of the red beet are the betalains. Similar to other natural plant colorants, betalains have a wide range of desirable bio-logical activities. Betalains are radical scavengers and show antioxidant activity, whereby they prevent active oxygen-induced and free radicalmediated oxidation of biological molecules (Pavlov et al. 2002). Together with the antioxidant activity, the betalains show anti-inflammatory, hepatoprotective, and anti-cancer properties (Georgiev et al. 2010); therefore, their presence in the human diet may reduce the risk of cancer, cardiovascular disease, and other diseases associated with aging (Pavlov et al. 2005). Kapadia et al. (1996) found that beetroot contains one of the most useful, natural, cancer-preventive agents. In the red beet, the main betalains are betanin (red) and vulgaxanthine I (yellow). According to previous inves-tigations, there is a very close relation between the content of red pigments and the antioxidant capacity of red beet, which shows that the red betanin is primarily responsible for the antioxidant activity, whereas a less strict relationship was found between the yellow pigments and the antioxidant capacity (Czapski et al. 2009). The stability of these pigments is low; nevertheless, the betalains remain stable in the gastroin-testinal tract without any significant loss in their antioxidative properties (Georgiev et al. 2010); however, particularly during heating and storage, they can degrade and lose their activity. Therefore, lactic acid fermentation can be an alternative method to preserve (even partially) the active components. The red beet can accumulate a significant amount of nitrates which, after consumption, can easily be reduced to nitrites in the human organism and can be hazardous to human health. Nitrite can react with secondary amines and result in nitroso-amino compounds. This reaction may occur either during food processing, in technological processes, or in the digestive tract (Halsz and Bartth 1998). At the same time, recent findings show that consumption of increased nitrate from red beet juice improves brain function and reduces blood pressure and the occurrence of cardiovascular diseases (Ahluwalia 2010; Presley et al. 2010). Furthermore, it should be mentioned that the red beetas the vegetable generallyis the source of several important minerals, vitamins (see the Introduction), and fibers.

Among the lactobacilli, there are several probiotic strains. After a circumspect selection, the probiotic strain can be used as starter culture; however, the starter culture can also show probiotic properties. The established benefits of probiotic strains are that they can improve the health of the consumers by their modulation of gut microflora composition (blocking of adhesion of pathogens and production of anti-microbial agents), antidiarrheal capabilities, enhancing the immune system function, and several other potential benefits which have been assigned to probiotics, such as preventing the occurrence of inflam-matory bowel disease, reducing the risk of colorectal cancer, and hypocholesterolemic effects (Tuohy et al. 2003; Rastall et al. 2005; Parvez et al. 2006).

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The health benefits of fermented foods have been well known for centuries. As early as AD 76, the Roman historian Plinio proposed the consumption of fermented milks for treating gastrointestinal infec-tions (Stanton et al. 2005); however, the scientific establishment of the beneficial effects of fermented foods began with Metchnikoff in the early 1900s. The health benefits of fermented red beet derive from the above-mentioned beneficial effects of red beet and LAB. These good properties exert their effect not only additively, but the LAB also protect the beneficial components of red beet and moreover can increase their effect. It was observed that the lactofermented red beet juice showed stronger antioxidant properties compared with the fresh juice (Walkowiak-Tomczak and Zieliska 2006). Klewicka et al. (2009) found that the intake of fermented beetroot juice containing live Lactobacillus cells positively modulated the cecal microflora and its metabolic activity in rats. If we use proven probiotic strains as starter culture or give probiotic strains in addition to the fermented red beet, the product has an increased health-promoting effect. Because most of the probiotic foods are dairy products, the fermented, probiotic red beet represents a perfect alternative to dairy products for consumers who do not want to eat milk-based food or are lactose intolerant or allergic to milk proteins.

20.5 Concluding Remarks

Lactofermented red beet combines the beneficial effects of the mineral-, vitamin-, and fiber-rich, high antioxidant source red beet with the health-promoting effects of LAB and results in a well-digestible, preservative-free, minimally or nontreated functional food with several health benefits. For such a prod-uct, a carefully selected starter culture is required, screened for biogenic amine and hydrogen perox-ide production, growth, and antimicrobial properties. Mainly, red beet juice (e.g., Beet Juice by Biotta (Tgerwilen, Switzerland) and Bio Red Beet Juice by Dr. Steinberger (Unkel, Germany)) and red beet powder made from juice (e.g., AIMRediBeets (Tucson, AZ), Whole beet plant juice tablets by Sonnes (Kansas City, MO), Beet Juice POWder by Eclectic Institute (Sandy, OR), and Beet Juice Powder by Pines International, Inc. (Lawrence, KS)) are present in the market, and to a smaller degree, the pickled form of red beet can be found. Nevertheless, the fermented form of red beet is not widespread, although knowledge of the health benefits of lactofermented red beets should be increased.

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20.1Introduction20.2Starter Culture Selection20.3The Process of Fermentation20.4Health Benefits of Fermented Products20.5Concluding RemarksReferences