What Are the Uses of Sweetener D Tagatose?

Tagatose (taga tose) is a naturally occurring but relatively rare hexoses, a diastereoisomer of fructose, with a relative molecular mass of 180∙16 and CAS 87-81-0. It is 92% as sweet as sucrose, has a similar sweetness profile, and produces only 1/3 the calories of sucrose, which is why it is called a low-calorie sweetener. In addition, tagatose has a good synergistic effect on strong sweeteners, including cyclamate, saccharin, aspartame, acesulfame, stevia, neotame and sucralose [1].

Tagatose is a good low-energy food sweetener and filler, and has a variety of physiological effects, such as inhibiting high blood sugar, improving intestinal flora, and not causing tooth decay. In 2001, the US FDA approved tagatose as GRAS. At present, it is widely used as a substitute for sucrose in products such as healthy drinks, yogurt, fruit juice, baked goods, candy, and pharmaceutical preparations (such as syrup and chewable tablets) [2].

Extensive safety and toxicology studies have shown that tagatose is safe and non-toxic. On April 11, 2001, the US FDA approved tagatose as GRAS for use in food. Subsequently, Australia and New Zealand also approved the use of tagatose in food. However, excessive consumption of tagatose may still cause mild gastrointestinal discomfort, such as flatulence and diarrhea, which may be mainly due to the body's impaired absorption of tagatose. In June 2001, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) approved tagatose as a food additive with an ADI of 0.80 mg/kg·d [2]. Based on this, this article discusses its physiological functions, production methods and applications in food processing in detail.

1 Physiological functions of tagatose

In recent years, tagatose has become a sweetener that has attracted widespread international attention. This is because tagatose has the following functions:

1.1 Does not cause blood glucose fluctuations

Tagatose is poorly absorbed in the body and does not cause significant changes in blood glucose levels, making it suitable for diabetics. Studies have shown that tagatose does not cause significant changes in fasting blood glucose or insulin levels in healthy subjects and type 2 diabetes patients, and can significantly inhibit the increase in blood glucose caused by glucose intake in diabetic patients, but has no significant effect on their insulin sensitivity.

Type 2 diabetic patients were given different doses of tagatose, and 30 minutes later, they were given 75 g of glucose. It was found that tagatose had a good inhibitory effect on the increase in blood glucose caused by glucose, and there was a certain dose-effect relationship [3].

1.2 Antioxidant [4]

Male mouse liver cells in vitro were exposed to furazolidone (a drug used to treat urinary tract infections). At a furazolidone lethal dose of 300 μM, high concentrations of tagatose (20 mm) completely protected the liver cells from damage. The same concentration of glucose, mannose and xylose has no protective effect. Tagatose can prevent lipid peroxidation reactions catalyzed by iron ions, thereby eliminating the damage to cells and the body caused by the free radicals produced. Hexoses like glucose and galactose do not have this property.

1.3 Regulating the intestinal flora

Only 20% of the tagatose consumed by the body is absorbed in the small intestine. The vast majority of tagatose enters the colon directly, where it is selectively fermented by the microflora, promoting the growth of beneficial bacteria and inhibiting the growth of harmful bacteria. This has a significant effect on improving the intestinal flora and is a good prebiotic. At the same time, the fermentation of tagatose also produces a large amount of beneficial short-chain fatty acids (SCFAs), especially butyric acid, which is a good energy source for colon epithelial cells and is considered to have a good effect in inhibiting colon cancer, inhibiting pathogenic bacteria in the intestine (such as Escherichia coli, etc.) and promoting the growth of beneficial bacteria such as lactobacilli.

After 14 days of daily consumption of 3×10g tagatose by 16 subjects, it was found that the fermentation rate of the fecal microorganisms in the test group was significantly higher than that in the control group that did not take tagatose. After 4 hours of fermentation, the amount of SCFA produced by the test group was 3 times that of the control group. Among these, the butyric acid content of the SCFA produced by the test group reached 35%, while the butyric acid content of the SCFA produced by intestinal fermentation in the human body is usually only 15% to 20%. It was not until 48 hours of fermentation that the butyric acid concentration in the control group began to increase, gradually approaching the level of the test group, indicating that the adaptation time of the human fecal flora to tagatose fermentation is 48 hours. In addition, the amount of lactic acid in the test group was also significantly higher than that in the control group [5]. A 1999 study concluded that the minimum dosage of tagatose that has a significant prebiotic effect is 7.5 g/d.

1.4 Non-cariogenic, inhibits dental plaque [6]

Studies have found that the use of toothpaste containing D-tagatose can prevent and eliminate dental plaque. On December 2, 2002, the US FDA officially confirmed that tagatose is not decomposed by oral bacteria, does not cause caries, and has the ability to prevent dental diseases such as gingivitis.

2 Preparation of tagatose

At present, there have been no reports of industrial production of tagatose in China. The main production methods used abroad are chemical catalysis, bioconversion and natural extraction.

2.1 Chemical catalysis

The chemical catalysis of tagatose uses galactose as the raw material and mainly includes two steps: isomerization and acid neutralization [7].

First, a soluble alkali metal salt or alkaline earth metal salt is used as a catalyst to isomerize galactose with a metal hydroxide to form a metal hydroxide-tagatose complex intermediate that precipitates. Then, the complex intermediate is neutralized with an acid to obtain the terminal product tagatose. Galactose can be obtained by hydrolyzing lactose.

The isomerization of galactose is the key step in the chemical synthesis of tagatose. For cost reasons, the metal hydroxide reactant is preferably Ca(OH)2 or a mixture of Ca(OH)2 and NaOH. It is generally added as a water-soluble slurry made by mixing Ca(OH)2 with water, or as a product of hydration after mixing with lime (CaO). The alkali metal salt (or alkaline earth metal salt) catalyst usually uses CaCl2, and the amount used is about 1% to 5% of the galactose molar number. The isomerization reaction should be carried out under alkaline and low temperature conditions, controlled within the range of pH>10 and -15 40°C.

The aim of acid neutralization is to form insoluble metal salts and release tagatose from the complex intermediate. The remaining ions are removed by ion exchange resins. H2 SO4, H3PO4 or HC l can be used for acid neutralization, with CO2 being the best. The progress of the acid neutralization reaction is controlled according to the pH of the reaction system. When pH<7, the neutralization reaction is complete.

2.2 Bioconversion method

One method of biotransformation is the biological oxidation of galactitol to tagatose by acetic acid bacteria [8]; another is the conversion of galactose to tagatose by L-arabinose isomerase [9 10]. The latter can be genetically engineered to improve the heat resistance and substrate specificity of L-arabinose isomerase. At present, the bioconversion of tagatose is still at the laboratory research stage. In domestic research, the School of Food Science and Technology at Jiangnan University has taken the lead in the bioconversion of tagatose and has made great progress. Lactobacillus strains with high yield of the required enzyme have been screened, and the enzyme production process by lactic acid bacteria fermentation has been optimized. Through research on the mechanism of bioconversion of tagatose, a process using lactic acid bacteria cells for the bioconversion of tagatose was proposed, and a galactose conversion rate of 39% was achieved. Tagatose is currently being produced using immobilized cell technology to improve the galactose conversion rate and obtain a process suitable for industrial production.

2.3 Natural extraction

Naturally occurring tagatose is found in nature in low concentrations in yogurt, milk powder and cheese. It is usually a product of microbial fermentation of lactose in dairy products. The gum of a tropical plant contains a polymer of tagatose. After hydrolysis, all the hydrolysate contains tagatose, which can be separated and purified to obtain the product. However, due to its very low content, it is difficult to meet the requirements of industrial scale production using natural extraction and separation.

The above production methods, including the bioconversion method, have certain competitive advantages in terms of process, cost and yield, and will become a promising method in the future. At present, the key is to obtain a microbial strain with high yield and strong vitality, so as to increase the production of tagatose and appropriately reduce production costs.

3 Applications of tagatose

Tagatose is a sweetener with properties similar to sucrose and can be used in the food industry as a complete substitute for sucrose. In 2001, the US Food and Drug Administration (FDA) officially approved tagatose as a sweetener for use in the food and beverage industry and in medicine. In 2003, tagatose was already being used in the US as a substitute for sucrose in health drinks and in products such as yogurt and fruit juice.

3.1 Baked goods

In many baked goods, tagatose is used as a flavor enhancer. Because tagatose has a high Maillard reaction, the amount added needs to be strictly controlled, otherwise it will taste bitter. Adding small amounts of tagatose to bread can increase the moisture content, improve the flavor, and enhance the color of bread and biscuits. Adding 2% tagatose to muffins produces a soft texture and a rich toffee flavor. Adding 0.5% to 1% tagatose to toast halves the baking time and produces a uniform color. Tagatose is an ideal sugar coating for low-energy foods, such as bread and cake fillings.

3.2 Chewing gum

Small amounts of tagatose in chewing gum can prolong the sweetness and give it a special flavor. It can be added to the gum or used as a sugar coating. Adding more than 15% can give flavors like thin oil and fruit, as well as enhance the flavor of peppermint oil and promote the sourness in some fruit flavors, but it does not increase the stickiness of the gum.

Tagatose can be used in combination with other polyols (xylitol) to compensate for the disadvantage of polyols, which is that their high use can lead to diarrhea.

3.3 Beverages

Low-energy drinks often lack body and flavor compared to drinks with high sweetness. Adding 1% tagatose to low-energy drinks can produce a better mouthfeel, mask undesirable flavors, reduce bitterness, and harmonize sweetness.

The addition of tagatose to milk-based drinks such as chocolate yoghurt and fruit yoghurt can improve the off-flavours caused by the use of high-intensity sweeteners, giving a good sweet taste with a long-lasting sweetness and reduced bitterness.

3.4 Application in meat products

Preserved meat, ham, etc. Meat products contain relatively high levels of carbohydrates (2%–7%), which can lead to microbial contamination and result in economic losses. In the meat industry, the requirements for preservatives and biocides are very strict, so the addition of carbohydrates that cannot be utilized by microorganisms to meat products can be considered. Tagatose cannot be utilized by lactic acid bacteria, which can cause putrefaction, and some pathogenic bacteria such as Escherichia coli, Salmonella, Staphylococcus aureus, etc. If added to meat products, it can not only perform the functional role of carbohydrates, but also prevent microbial contamination.

3.5 Health food

Tagatose can be used as a raw material for health food products because it has a prebiotic effect, can effectively improve intestinal flora, and prevent colon cancer.

3.6 Other applications

In medicine, tagatose is used in cough syrups, as an excipient and foaming agent in pharmaceuticals, as a denture adhesive, as a moisturizer in toothpaste and mouthwash, as a mouthwash and oral disinfectant, and as a moisturizer and stabilizer in cosmetics. Tagatose is also used to treat diabetes and iron deficiency anemia as well as scurvy.

4 Tagatose enters commercial applications [11］

In August 2003, PepsiCo officially used tagatose in their Sprite drink as a flavor enhancer, which was the first time tagatose entered the commercial field. The company believes that adding tagatose to carbonated drinks that currently use high-intensity sweeteners improves the flavor and texture of the product. New Zealand's Mia-da Sports Nutrition Food Company has applied tagatose to the development of chocolate products. The first products developed include chocolate bars in different flavors, such as milk, chocolate, dark chocolate and white chocolate. Further products include chocolate-covered dried fruits, dried fruit bars, Easter eggs and other innovative chocolate products. According to BCC forecasts, the new tagatose market will grow at a steady rate of 20% to 25% over the next five years.

At present, although the mechanism of action of D-tagatose as a new type of monosaccharide in the human body needs to be further explored, its excellent physical and chemical functional properties are undeniable. It is expected that in the next few years, D-tagatose will become a best-selling natural sweetener on the international market and will be widely used in food, medicine, cosmetics and other fields, with very broad market prospects.

Reference:

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