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Clicking on the donut icon will load a page at altmetric. Find more information on the Altmetric Attention Score and how the score is calculated. In recent years, red beetroot has received a growing interest due to its abundant source of bioactive compounds, particularly betalains. Red beetroot betalains have great potential as a functional food ingredient employed in the food and medical industry due to their diverse health-promoting effects.
Betalains from red beetroot are natural pigments, which mainly include either yellow-orange betaxanthins or red-violet betacyanins. However, betalains are quite sensitive toward heat, pH, light, and oxygen, which leads to the poor stability during processing and storage. Therefore, it is necessary to comprehend the impacts of the processing approaches on betalains. In this review, the effective extraction and processing methods of betalains from red beetroot were emphatically reviewed.
Furthermore, a variety of recently reported bioactivities of beetroot betalains were also summarized. The present work can provide a comprehensive review on both conventional and innovative extraction techniques, processing methods, and the stability of betalains. Food Chem. More by Yu Fu. More by Jia Shi. JECFA Evaluation of certain food additives and contaminants. Technical Report Series No.
Red beets is a vegetable with a low fat content, but rich in carbohydrates, starch, soluble fibers, proteins, being a product with moderate caloric value. Beet roots are rich in vitamins C, A, E, K. They have an important content of B-vitamins B 1 - thiamine, B 2 -riboflavin, B 3 -niacin, B 5 -pantothenic acid, B 6 -pyridoxine, B 9 -folates and B 12 -cyancobalamin , as well as folic acid and powerful antioxidants, such as triterpenes, sesquiterpenoids, carotenoids, coumarins, flavonoids tiliroside, astragalin, rhamnocitrin, rhamnetin, kaempferol , betalains and phenolic compounds.
Other bioactive compounds that are found in beets are: saponins, alkaloids calystegine B 1 , calystegine B 2 , calystegine C 1 , calystegine B 3 , ipomine , amino acids threonine, valine, cystine, methionine, isoleucine, leucine, lysine, phenylalanine, histidine, arginine, glutamic acid, proline, alanine, tyrosine - in leaves , tannins.
Beet roots are a good source of minerals, like manganese good for bone health , magnesium, potassium, sodium, phosphorus, iron, zinc, copper, boron, silica and selenium [ 5 , 11 , 12 , 14 , 15 ].
The chemical composition differs depending on the red beetroot variety. The range of the chemical composition and distribution of the nutritional compounds of red beetroot depends on the anatomical part of the plant leaf, stem, root, peel [ 16 ]. Beetroot leaves are richer in carotenoids compared to tubers. Green leaves and stems are a perfect solution in obesity problems and weight management, as they are typically low in calories. The high level of vitamin A, K and C is important for the production of a protein essential for bone health.
Green leafy vegetables are a major source of iron and calcium for any diet. Leafy vegetables are used in preventing chronic diseases, such as cancer, cardiovascular disease and diabetes, as they have anti-inflammatory and anticarcinogenic activity. Beetroot leaves are used to reduce blood pressure [ 18 , 19 ].
Red beet is a significant source of polyphenols, which together with the betalains, show a high antioxidant effect and radical scavenging capacity. The composition of the various nutrients of red beet is shown in Table 1. Table 1: Composition of raw red beetroot flesh per g [5,8,11,52,67].
View Table 1. Carotenoids are an important class of compunds, also called tetraterpenoids, which are organic pigments. The carotenoids from red beetroot are not representative being in small quantities [ 20 ]. Even lycopene, the red carotenoid has reported a significant attention from the antioxidant point of view, it seems that red beetroot is not a very valuable source of lycopene.
So, considerable amounts of lycopene are in tomato, watermelon, red-fleshed guava, papaya [ 21 ]. Betalains are a class of water-soluble and nitrogen-containing pigments,synthesised from the amino acid tyrosine, and fall into two structural groups, i.
Betalains are found in different plant organs, and accumulate in cell vacuoles, mainly in epidermal and subepidermal tissues [ 22 , 25 ]. The pigments are stored in vacuolar juice or in chromatoplasts visible in parenchymal cells, in the vicinity of plasmalemma. Betalains are water-soluble, vacuolar, secondary metabolites, being phenolic chromoalkaloids with health benefits for humans, especially in point of their antioxidant, anti-inflammatory, antiviral, even anti-tumoral activities.
Betalains are secondary metabolites derived from the amino acid L-tyrosine: Betaxanthins are immonium derivatives of betalamic acid with different amines and amino acids, and betacyanins, where the betalamic acid appears condensed with cyclo-dihydroxyphenylalanine cyclo-DOPA [ 26 , 27 ].
The color stability of betalains is strongly influenced by pH and heating. They are stable at pH to , but their thermostability is the greatest between pH 4 and 5 [ 24 , 28 ]. This reaction is reversible. Betanin is light and air dependent. These effects are cumulative, but some protection may be offered by antioxidants such as ascorbic acid.
Small amounts of metal ions increase the rate of betanin degradation. Therefore, a chelating agent or some protein systems can stabilize the color. In addition, studies on the stability of betalaines demonstrate that the susceptibility to temperature of betaxanthin is higher than that of betacyanin [ 29 , 30 ].
Figure 1: Degradation of betanin [ 22 ]. View Figure 1. Betalains are also used as additives in the food industry on account oftheir natural colorant properties, high solubility in water and lack of toxicity. One was inhibited by tyrosine — a natural way to regulate the amount of the amino acid, by shutting off production when there is a lot of it. But the second enzyme was much less sensitive to regulation by tyrosine, meaning it could keep making the amino acid without being slowed down.
The upshot was that beets produced much more tyrosine than other plants, enough to play around with and turn into betalains. Figuring that humans had bred this highly active tyrosine pathway while selecting for bright-red beets, Lopez-Nieves isolated the enzymes from wild beets. That was unexpected.
So he turned to spinach, a more distant cousin that diverged from beets longer ago. Spinach also had two copies, one that was not inhibited by tyrosine, meaning the new tyrosine pathway must be older than the spinach-beet ancestor.
The researchers needed to go back much further in evolutionary time to find when the ancestor of beets evolved a second, less inhibited enzyme. Portulaca oleracea purslane.
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