Maltol (maltol), also known as methyl maltol, chemical name 3-hydroxy-2-methyl-4H-pyranone, FEMA No. 2656, relative molecular mass of 126.11, white acicular crystals or white crystalline powder, melting point 160 ~ 164 ℃. Maltol exists in the bark of the sheep’s tooth leaf and the larch tree, and a small amount of maltol also exists in some food materials such as roasted chicory, caramel, roasted coffee, cocoa, cereals and bread crusts.

Ethyl maltol that ETHYL MALTOL referred to as EM, chemical name 2-ethyl-3-hydroxy-4H-pyrone, FEMA No. 3487, relative molecular mass of 140.14, melting point of 89-92 ℃, is a more commonly used high-efficiency synthetic aroma enhancers, add a small amount of the product can be made more intense flavor, and maintain a longer period of time.

At present, the National Standard for Food Safety Food Additives Ethyl Maltol (GB 1886.208-2016) and the National Standard for Food Safety_Food Additives_Maltol (GB 1886.282-2016) have made requirements for the sensory and physicochemical indexes of ethyl maltol and maltol.

Classification and identification of ethyl maltol

1.Classification of Ethyl Maltol

Ethyl malt phenol is classified according to its characteristics: pure flavor, burnt flavor and extra alcohol. It is mainly used in food flavor, daily flavor, light-sensitive materials, antiseptic and skin care products.

1.1 Pure aroma type
Characterized by soft fruity and milky aroma. Added to meat products can significantly improve the fruit flavor, inhibit bitter, sour, astringent taste, to obtain the most suitable fruit flavor and sweet taste, at the same time, to obtain excellent taste. In meat products more than corn, peanuts and other meat and vegetables with the type, and can be used in conjunction with the special alcohol type.

1.2 Caramelized aroma type
To the head of the obvious aroma, through the hair, there is a very strong caramel flavor as the characteristics of the original sweet and fresh flavor of various foods have a very strong synergistic effect. Especially added to a variety of meat products, such as: with smoked, roasted, charcoal grilled flavor of barbecue, barbecue sausage, barbecue and other products, and the amino acids in the meat and play a role in significantly improving the meat aroma and freshness, so that the flavor is more prominent.

1.3 Special alcohol type
This type of ethyl malt phenol has the advantages of high purity, high quality, high whiteness, unique aroma, etc. The characteristic flavor is more prominent, the burnt flavor is mellow and rich, and the aftertaste is long after being dissolved by heat, and the aroma lasts for a long time. While maintaining the original characteristic flavor of meat products, it can maximize the concentration of aroma, and has the effects of acid suppression, bitterness suppression, deodorization and antiseptic. Apply to highlight the meat texture of high-grade ham, brine ham, high-grade meat sausage and other poultry products.

2. Shoddy ethyl maltol identification methods

2.1 Tasting method

The flavor of ethyl maltol is slightly bitter, slightly spicy and astringent. Counterfeit ethyl maltol taste sweeter.

2.2 Heating method

Put a small amount of ethyl maltol on tin foil (tin foil inside cigarettes can also be used) and heat it up with alcohol lamp or lighter, the ethyl maltol will be melted after being heated up and continue to be heated up, and the melted ethyl maltol will be completely evaporated without leaving any impurities. For counterfeit or low purity of ethyl maltol according to the above method of operation, it will leave a burnt substance on the tin foil.

2.3 Dissolution Method

First observe the dissolution of ethyl maltol in cold water, purity of 99.2% of ethyl maltol is very difficult to dissolve (solubility in water 1:55), and was floating, will not soon precipitate; followed by hot water rushed to quickly form a transparent solution. If you drop ferrous sulfate in the solution will quickly turn red, according to the redness can be identified by its purity.

Physical and chemical properties

From the physical properties, maltol is a white crystalline powder, with the same characteristic odor as caramel, and its dilute solution has a slight strawberry fragrance; maltol can be soluble in hot water, ethanol and chloroform, in cold water at room temperature can be dissolved in 1.5%, in the 90 ° C hot grease can be dissolved in 2%, difficult to dissolve in ether, benzene, petroleum ether. It sublimates at 90℃, the threshold value is 0.03%.

Maltol aqueous solution is acidic, meet the alkali salt is formed, meet the ferric chloride is purple-red. It also has a candied fruit aroma, and its dilute solution has a slight strawberry fragrance. Under acidic conditions, maltol has a better flavor enhancement effect, with the gradual increase in pH value, the fragrance gradually weakened; alkaline conditions, the fragrance is significantly weaker.

Ethyl maltol is white or yellowish crystal, yellow color when meet alkali, easily soluble in hot water, ethanol, chloroform and glycerol, with caramel flavor and fruit flavor. Solubility of ethyl maltol: at 15℃, 1g can be dissolved in 65ml of water, at 25℃, 1g can be dissolved in 55ml of water, because of its aroma-enhancing effect is 4-6 times greater than that of malt phenol, 1 portion of ethyl maltol can be used instead of 24 portions of coumarin.

Specific dissolving method:

1g of maltol is soluble in approximately 82mls of water, 21mls of 95% ethanol, 28mls of propylene glycol or 18mls of chloroform.

1 g of ethyl maltol is soluble in about 55 ml of water, 10 ml of 95% ethanol, 17 ml of propylene glycol or 5 ml of chloroform.

In terms of chemical structure and property characteristics (Figure 1), the two are very similar. They have aroma-enhancing properties due to their ability to sublimate at lower temperatures. In addition, maltol and ethyl maltol are able to form chelates with metals and have reducing properties, which allow them to be used as antioxidants to prevent undesirable flavor reactions in foods, such as overcooking of cooked meats.

Figure 1 Molecular formula of maltol and ethyl maltol

Ethyl maltol is a derivative of γ-pyrone, a broad-spectrum efficient flavor enhancer, can also be used as a sweetener, aroma synthesizer, aroma improver and aroma fixative, with acid inhibition, bitterness inhibition, deodorization, and de-irritation effects. These and maltol have the same characteristics, the difference is that maltol can be obtained from nature (barley, soybeans, etc.), while ethyl maltol can be synthesized.

Flavor properties

The flavor and aroma of maltol and ethyl maltol are similar, with the major difference being that the flavor intensity of the latter is about three to four times that of the former.

Specifically, maltol has a sweet, caramelized aroma, but not enough fruity smell; ethyl maltol has a sweeter, more intense flavor with a stronger fruity taste and a longer-lasting aroma. This makes the two different in terms of application, with Maltol being particularly suitable for vanilla, chocolate and caramel flavors, while Ethyl Maltol is an excellent fruity, sweet and floral aroma enhancer.

Functionality

As basic flavor ingredients maltol and ethyl maltol are essential ingredients in many complex flavors and are used in the formulation of many fruit flavors.

4.1 Improvement of food flavor

Maltol and ethyl maltol enhance the overall flavor profile of many flavorings, creating a smooth and harmonious flavor. Typical dosage levels are 2-250 ppm and 1-100 ppm when used as flavor modifiers.

4.2 Increase and improve sweetness

The sweetening properties of maltol and ethyl maltol can reduce the amount of sugar used. It has been reported that the addition of 15 ppm maltol or about one-fourth of the amount of ethyl maltol to non-carbonated fruit beverages can achieve the desired sweetening effect and reduce the amount of sucrose by 5-15%.

On the other hand, when combined with high sweetness sweeteners, it can improve the unbalanced, discontinuous and strong taste quality of sweeteners, which can help to make the flavor of the product closer to sucrose, and the sweetness obtained is more complete and balanced.

4.3 Modifying bitter and astringent flavors

Maltol and ethyl maltol are generally used to mask the bitter taste in food or pharmaceutical products, to lighten the astringent taste of food, and to inhibit the aftertaste produced by sweeteners, so that the food has a balanced flavor.

4.4 Enhancement of creamy and smooth texture

Maltol and ethyl maltol have the effect of enhancing the sense of milk fat in dairy products, and can produce a smooth taste similar to high-fat food, which is conducive to the development of delicious reduced-fat, low-fat and fat-free advanced dairy products.

4.5 Reduce sour taste and acid stimulation flavor

Maltol and ethyl maltol can improve the overall flavor of foods by reducing their overall acidity, which is particularly beneficial for the development of microbiologically stable low pH foods and flavors. At the same time, they can inhibit the acidity associated with some food additives, resulting in a softer flavor.

4.6 Improving the flavor of microwave-cooked foods

Basically, the rapid, low-temperature cooking method of microwave ovens can cause foods to lack their proper flavor, and maltol and ethyl maltol have unique features that can help improve the flavor of such foods.

Scope of Application

5.1 Situations where additive use is not allowed

GB 2760-2014 stipulates that “food flavors and fragrances should be used in appropriate amounts in all kinds of foods according to production needs, and the foods listed in Table B.1 are not necessary to be flavored, and food flavors and fragrances should not be added, except for those explicitly stipulated by laws, regulations or national food safety standards.” For example, pasteurized milk, sterilized milk, fermented milk, vegetable and animal fats and oils, fruits and vegetables, fresh meat and fresh aquatic products, fresh eggs, etc. in dairy products.

The content of ethyl maltol is also regulated in the product standards concerning vegetable oils, for example, the standards for Canola Oil (GB/T 1536-2004), Sesame Oil (GB/T 8233-2018), and Soybean Oil (GB/T 1535-2017) stipulate that no flavors and fragrances should be added. Therefore, ethyl maltol is not allowed to be added to vegetable oils for use as a means of adulteration or flavor enhancement.

Determination of Ethyl Maltol in Edible Vegetable Oils (BJS 201708) can be used to test the content of ethyl maltol in rapeseed oil, sesame oil and sesame blending oil, so as to confirm whether there is any adulteration by manufacturers and determine whether the products comply with the provisions of the relevant standards. The test standard effectively regulates the adulteration of sesame oil in the market, which not only provides a strong technical support to investigate and deal with illegal acts outside the vegetable oil standard, but also provides the necessary technical support for the detection and control of food safety.

5.2 Application in Foods Allowed to be Added

Due to its superior performance, ethyl maltol is more and more widely used in the current food industry, and different types have different enhancement effects in food.

For example, in fruit juice, beverages, cold beverages, alcohol, spices, add pure aroma type ethyl malt phenol can obviously enhance the sweet taste of fruits, good eating taste; caramel type ethyl malt phenol has a very strong caramel flavor, suitable for meat products, canned goods, spices, confectionery, cookies, chocolate, cocoa products, etc., and can be reacted with the amino acids in meat products, obviously improve the fresh flavor of the meat products to make it more prominent; Extra alcohol type ethyl malt phenol has different enhancement effects in the food. It can react with amino acids in meat products to enhance the fresh flavor and make the flavor more prominent. Special alcohol type (enhanced caramel type) ethyl malt phenol has a prominent characteristic flavor – caramel flavor is mellow and rich, and the aroma time is more persistent, which is suitable for the production of high-grade ham and meat sausage and other meat products.

In beverage products, maltol and ethyl maltol can increase and improve the flavor of beverages, applicable to citrus orange, pear, pineapple, cherry, grape, strawberry, mango, apple, coconut and passion fruit and other fruit-flavored sweet drinks. In fruit wines, maltol and ethyl maltol act as flavor stabilizers, reducing acidity and giving the wine a pleasant aroma.

In addition, the modifying, harmonizing and aroma-enhancing properties of maltol and ethyl maltol are one of the reasons why flavored coffee and tea have become so popular in recent years. In addition, maltol and ethyl maltol have been used in low-calorie beverages with high sweetness sweeteners to improve the flavor of the product.

Table 1 Reference amounts of maltol and ethyl maltol in some food products

Partial source; Haiyan Yang. Multifunctional flavor enhancers – maltol and ethyl maltol[J]. Ingredients,1998, 5 ( 11) : 29~31

5.2.1 Dairy products

In the manufacture of smooth and rich ice cream, frozen milk and frozen yogurt, maltol and ethyl maltol can be used to improve the creamy texture of the product, as well as flavor characteristics such as vanilla, strawberry and chocolate. In addition, a variety of reduced-fat, low-fat, and fat-free products can be made with the use of maltol and ethyl maltol to increase the creamy, smooth texture of the product.

5.2.2 Sweets

Maltol and ethyl maltol can make the flavor of vanilla and chocolate pudding more fragrant and beautiful, and can reduce the starch flavor and paste-like texture, further improving the quality of the product. Applied in jelly products, it can make the flavor more intense and the acidic flavor more calm, so that the product exudes a truer and more natural fruit flavor.

5.2.3 Bakery products

As maltol and ethyl maltol have sweet and burnt flavor, they are ideal aroma enhancers for bakery products. For example, cakes made with 50~100ppm ethyl maltol have a more fragrant and rich taste.

When applied to the fillings of baked goods, no matter it is fruit fillings, milk cake fillings, pudding type fillings or all kinds of cream fillings, the result is excellent. Its ability to improve flavor has led to great interest in low-fat baked goods where low cream dosages and no butter or shortening are used.

5.2.4 Confectionery and Chocolate Products

The addition of maltol and ethyl maltol to chocolate products enhances the smoothness of the rich fat flavor and reduces the bitterness of the chocolate itself.

5.2.5 Condiments and sauces

Maltol and ethyl maltol have different uses in different condiments, for example, in strawberry sauce to increase its sweetness and aroma; and in ketchup to reduce its acidic pungent flavor. In the area of low-oil, low-calorie condiments, it is clear that reducing the amount of oil and carbohydrates can affect the flavor of the product, and maltol and ethyl maltol can correct this negative effect by moderating the astringent and incongruous flavors of these products.

5.2.6 Meat products

The addition of maltol or ethyl maltol to the processing of poultry meat products, in conjunction with additives such as ferric citrate, zinc gluconate, etc., can play a good role in color development. For example, ethyl maltol added to minced meat, can form a purple-red complex to improve the color of marinated minced meat, delay the oxidation of fat, and at the same time can improve the meat flavor of minced meat products, 0.02% of ethyl maltol added with 0.03% ascorbic acid and 0.03% of the use of tea polyphenols to improve the effect of minced pork products color.

5.2.7 Other applications

In addition to their wide range of uses in food, maltol and ethyl maltol can also be applied in many other areas. For example, they have been widely used in pharmaceutical products such as vitamins and cough syrups to reduce the bitterness of certain active ingredients, as well as in other non-food applications.

5.2.8 Timing of addition

Ethyl malt phenol is used as flavor enhancer, the dosage is small, the general addition amount is 0.003%, sometimes only a few ppm will be effective, the dosage is too much will make the product have a caramel flavor. Because some ethyl maltol homologue can work very effectively at very low concentration, so when adding to food, it should be weighed accurately or adjusted to a concentration of 0.5% or less (such as 0.25%) of the storage solution (Note: the storage solution should be kept in brown glass bottles), and then added to the food according to the formula of the optimal concentration.

The timing of adding ethyl malt phenol is important according to the different processing techniques and product characteristics, such as the process of cooking and smoking products, as well as seasoned and cooked food, etc. The timing of using ethyl malt phenol is important, and the timing sometimes directly affects the presentation of the characteristics of the product.

Generally speaking, the timing of adding ethyl malt phenol can be chosen according to the characteristics of the product, such as the addition of tumbling liquid, the addition of powdered products at a later stage, the addition of chopped products at a later stage, and so on.

Precautions and special tips for use

1、Used in production is generally added at the later stage of heating in the production process, such as beverages, bakery products, cold drinks, wines and flavors added together.

2、Because of the ethyl malt phenol solution easily and iron complex, the color becomes red, so the solution should not be in contact with iron, should be kept in glass or plastic containers.

3、Ethyl malt phenol is yellow when it meets alkali, so when the color of some products should not be yellow, alkaline raw materials and additives should be avoided.

4, when adding, such as to be added to the production process needs to be heated products, should be added as far as possible in the lowest temperature, in order to reduce the chance of volatilization.

5, if applied to the use of dry mixing production, they should be pre-mixed with one of the ingredients, and then completely mixed with the other ingredients, in order to achieve a homogeneous mixing effect.

6、Used in baked food, should choose to add when the clarity is low, the effect is better.

7、Used in acidic products, the effect of acid suppression and coordination, aroma and sweetening is more significant, and the PH value is gradually weakened by the increase in flavor.