What Are the Benefits of Vegetable Glycerin?

Vegetable glycerin, also called glycerol, is made from soybean, coconut or palm oil, so it contains no animal products. Glycerin is used to keep foods moist, help mix oil- and water-based ingredients and sweeten foods. It also has some medical uses and may have some beneficial effects on hydration during exercise.

Keeps Foods Moist

Manufacturers add glycerin to foods, including baked goods, fudge, candy and nutrition and energy bars, to help maintain their water content. It can also help keep ice crystals from forming in reduced-fat frozen desserts. Other foods that may contain glycerin include dairy products, soups, sauces, condiments, processed meats and seafood and water-based flavored drinks.

Adds Sweetness

Vegetable glycerin is sometimes used as an alternative sweetener in foods for diabetics and a number of low-carbohydrate processed foods. It's actually less sweet than sugar and has more calories, but because it falls into the same group of carbohydrates as sugar alcohols, it doesn't affect blood sugar levels or affects them less than sugar, according to licensed dietitian/nutritionist Monica Reinagel. Glycerin is well absorbed by the body and then converts to glucose, however, so it may have an effect on blood sugar more similar to sugar than to sugar alcohols.

Relieves Constipation

Large amounts of glycerine can cause a laxative effect, so it's sometimes used as a medicine to help relieve constipation, usually in the form of a suppository. It isn't recommended for this use if you're diabetic or have kidney problems, however, because it could make these conditions worse.

May Limit Dehydration

A study published in the Journal of Athletic Training in 2004 found that drinking a beverage containing glycerin before the race along with water during the race appeared to help limit dehydration and heat strain in mountain bikers. This was a very small study, however, with a total of just 12 participants, so further research is necessary to verify these results.

Side Effects of Vegetable Glycerin

Vegetable glycerin, also called glycerol, is sometimes used as a food additive in baked goods, candy, fudge, dairy products, meat, pasta, cereals, processed fruits and vegetables, condiments, soups, sauces, egg products and fish products. Sometimes it is used to help maintain moisture levels or mix oil- and water-based ingredients, but it can also be used as a sweetener. The U.S. Food and Drug Administration regards it as generally safe, though the additive can have some side effects in large amounts.

Laxative Effect

The small amount of vegetable glycerin used in food products isn't likely to cause side effects. It is classified as a sugar alcohol, though, and in turn can have a laxative effect when consumed in large amounts. Thus, it may cause diarrhea, excessive urination and dehydration if you eat a lot of it. Glycerin suppositories are used to relieve constipation because of this effect.

Other Side Effects

The more common, less serious side effects that can occur when you consume large amounts of vegetable glycerin include nausea, vomiting and headache. Lying down after taking medicinal amounts of vegetable glycerin can help limit the risk of headache and help relieve headaches that do occur, according to PubMed Health. When used as a medicine, glycerin must be prescribed by a doctor and used under medical supervision.

Rare Side Effects

Some less common side effects that warrant immediate medical attention include confusion and irregular heartbeat. These would be extremely unlikely to occur with the small amounts typically used in foods, as they aren't common even in medicinal doses.

Potential Allergic Reactions

Vegetable glycerin is made from either palm oil or coconut oil, so if you're allergic to either of these oils, you should avoid vegetable glycerin. Otherwise, it could cause an allergic reaction, with symptoms including difficulty breathing, swelling, rash, itching and anaphylaxis. Use animal-based forms of glycerin, which are made from beef tallow or other animal fats, or synthetic glycerin, which is made from corn syrup, sugar cane or a petroleum derivative called propylene, instead.

Foods Containing Glycerin

Glycerin, also called glycerol, is sometimes added to foods to help thicken them, to control their moisture level or to stabilize them if they contain a mix of water and oil. It's mainly used in processed foods and sweets and is generally regarded as safe by the U.S. Food and Drug Administration.

Dairy and Protein Foods

Dairy products, including cheese, yogurt and powdered milk or cream, are among the potential sources of glycerin. You may also find glycerin in condensed milk, whey products, pudding, clotted cream and dairy-based drinks. Processed meat and poultry, soybean products, processed seafood, dried eggs, canned eggs and egg-based desserts can contain this additive as well. Check the ingredients list to verify whether individual products contain glycerin.

Processed Vegetables and Fruits

Vegetables and fruits generally don't contain glycerin unless they're processed. Some examples of vegetables that could have glycerin include dried vegetables, canned vegetables, processed fruit, precooked vegetables and sauces containing vegetables. If you'd like to avoid glycerin, opt for fresh fruits and vegetables or those frozen without any added sauces.

Grains and Baked Goods

Precooked pasta, rolled oats, breakfast cereals, rice or tapioca pudding, breading or batters, precooked rice products and baked goods are all potential sources of glycerin. The less processed a grain-based food is, the less likely it is to contain glycerin. Baking goods and cooking grains yourself will help you limit your glycerin intake.

Other Foods

Many other foods can also be sources of glycerin. Some potential beverage sources of glycerin include alcoholic beverages, cider and flavored beverages made with water. The little extras you add to your food, such as sauces, vinegar, mustard, condiments, table-top sweeteners, butter and similar spreads, and nut butters may contain glycerin, and so can candies, soups and edible ices. Foods with added sweeteners sometimes contain glycerin because of the sweet taste it imparts.

Glycerine Substitutes

Glycerin, also referred to as glycerine or glycol, is a simple compound with a sweet taste. Glycerin is used in the food industry, in cosmetics and toiletries, in pharmaceutical products and botanical extracts, and as a component in antifreeze. Alternatives to glycerin are available for all of these applications. Some cheaper substitutes for glycerin in chemical applications are toxic and dangerous if present in food or cosmetic products.

Diethylene Glycol

Diethylene glycol, or DEG, is a liquid with a sharp sweet taste. It is naturally viscous, odorless and colorless. DEG is used as an intermediate substance in the production of chemical products such as polyurethanes, polyester resins and ethylene glycols. DEG can also be used as an antifreeze, as a humectant in tobacco, and as a solvent in cosmetics and paints. DEG can substitute for glycerin in these industrial applications, but is not approved for human consumption in many countries. The Australian government reports that DEG sold as counterfeit glycerin was found in toothpastes and cough syrups, leading to a toothpaste recall in Australia in 2007.

Propylene Glycol

Propylene glycol is a colorless, odorless liquid with similar humectant, or moisturizing, properties to glycerin. Also known as PG, propylene glycol is commonly used as a glycerin substitute in cosmetic and toiletry products because it is typically cheaper. Derived from petroleum, high-level and concentrated exposure to PG is believed to cause abnormalities of the liver, brain and kidneys. PG is found in commercially available stick deodorants, shampoos and other cosmetic products.

Ceramides

Ceramides may be substituted for glycerin in skincare products such as moisturizers and lotions. EczemaNet indicates that skincare products containing glycerin may increase the dryness of your skin if you suffer from atopic dermatitis. Using ceramides instead of glycerin in moisturizing lotions can help regulate your skin cells. Like glycerin, ceramides have a moisturizing effect, working to repair damaged skin. If your skin is particularly dry or prone to cracking, ceramides may be a good moisturizing substitute for glycerin.

Oils and Butters

Vegetable glycerin is often used as a natural skin care ingredient, according to Dinah Falconi's 1997 book "Earthly Bodies and Heavenly Hair." Glycerin substitutes include various naturally derived carrier butters and oils which have a similar moisturizing effect to glycerin. If your skin is naturally dry and the dryness is exacerbated by glycerin, you may find that shea butter, jojoba oil, cocoa butter or avocado oil are effective substitutes.

Types of Glycerol

There're four extraction methods for glycerol, namely saponification glycerol, synthetic glycerol, compound glycerol, fermented glycerol. Their performances and uses are basically the same, but their market quotation is much different.

1. Saponification Glycerol

Saponification glycerol is the hottest and in great demand on the current market, hydrolyzed from oil. We mainly get it from soap production in our country, commonly known as saponification glycerol. Saponification glycerol is a by-product of saponification of natural oils into soap. In recent years, soap and saponification glycerol production has been restricted due to the gradual replacement of soap by laundry detergent, making it difficult for saponification glycerol to achieve a breakthrough development.

2. Synthetic Glycerol

Synthetic Glycerol is synthesized from epoxy chloropropane (ECH), another popular glycerol in the market, as well. The annual production capacity of ECH is about 45000 tons in our country, but due to the serious shortage of chlorine gas and propylene, the production capacity is unable to be exerted. Because the insufficient raw materials, price hanging upside down, manufacturing loss and no incentive to produce for manufacturers, the output of synthetic glycerol is stagnant, hard to be increased in this way. If the production capacity of ECH could be increased greatly, this would be an effective way to produce glycerin.

3. Compound Glycerol

Compound Glycerol is produced from distillers' grains. At present, it occupies a small proportion in the market and its price is about 6.000 Yuan per ton. The production of compound glycerol is simple, with low price, and available raw materials, able to be produced in large numbers. But cannot be blindly developed in view of the sluggish sales. If the quality could be further improved, it'll undoubtedly be an important way to solve the long-term shortage of glycerin and dependence on import in China. Meanwhile, it could also be exported in large quantities.

4. Fermented Glycerol

Fermented glycerol is made by fermentation with starch such as corn, potato and saccharic such as sugar beet and sugar cane as raw materials. It is reported that all the important indicators of fermented glycerol  reach international advanced level, and free of arsenic, heavy metals and other harmful substances. Therefore, fermented glycerol could be used not only in the coating industry, but also in other industries like medicine, food, cosmetics, tobacco, toothpaste.

In 1859, Pasteur pointed out that glycerin is formed during the fermentation of yeast alcohol, as a by-product. During the first world war, due to the shortage of oil, glycerol produced by saponification of oil was far from enough to meet the demand in Germany. Therefore, German began to study fermentation method to produce glycerol, and developed the technology of adding sulfite to produce glycerol.

In recent decades, the United States, Japan, Sweden and China all have been actively engaged in the research of glycerol fermentation production, making it get rapid development at home and abroad. Due to the abundant source of raw materials, low price and mature technology, it is expected that in the near future, this kind of glycerol production will become an important method to alleviate the tension of glycerol in China.

Enzymatic Analysis of Glycerol

There are many reports of enzymatic determination of glycerol, but there are basically three enzymes. That is, glycerol oxidase, glycerol inactivating enzyme, glycerol dehydrogenase.

 

• Oxidase method

If glycerol is decomposed by glycerol oxidase, it is converted to glyceraldehyde and hydrogen peroxide. The hydrogen peroxide was synthesized by peroxidase and 4-aminoantipyridyl carbamate and phenol to form red compounds. The spectroscopic analysis was carried out at 546 nm. In addition, the oxygen consumed can also be determined directly with an oxygen electrode.

 

• Activating Enzyme Method

In the presence of ATP (adenosine triphosphate), glycerol is decomposed by glycerol-inactivating enzymes and converted to glycerol phosphoric acid and ADP (adenosine diphosphate).

glycerol + ATP →Glycerol-3-phosphoric acid +  ADP

Glycerol was quantitatively determined by the following enzymatic reactions with glycerol-3-phosphate and adenosine diphosphate.

In the presence of oxygen, when glycerol-3-phosphoric acid is used, glycerol-3-phosphoric acid reacts with oxidase and converts to dihydroxyketone phosphoric acid and hydrogen peroxide. At this time, the content of glycerol can be quantitatively determined by directly measuring the consumption of oxygen or by using oxygen electrode to determine the consumption of oxygen.

In addition, hydrogen peroxide can be quantitatively determined by spectroscopic analysis at 546 nm, using peroxidase and 4-aminoantipyridine and phenol to form red compounds.

In addition, glycerol-3-phosphate and NAD [coenzyme A (pyridine diphosphate nucleotide)] were transformed into dihydroxy ketone phosphate and NADH (reductive coenzyme A) by glycerol phosphorus dehydrogenase. The NADH was analyzed at 340 nm, and the content of glycerol could be quantitatively determined.

Glycerol-3-phosphoric acid +NAD →Dihydroxy ketone phosphoric acid+NADH

When ADP (adenosine diphosphate) is used, phosphoenol group and ADP are converted to pyruvate and A TP (adenosine triphosphate), then pyruvate and NAD (coenzyme A) are reacted to convert pyruvate (lactic acid) dehydrogenase to pyruvate and NADH (reduced coenzyme A).

ADP+Phosphoenolenol→ Pyruvic acid+ATP
Pyruvic acid+NAD→pyruvate+NADH

The determination of NADH can quantitatively determine glycerol.

 

• Dehydrogenase Method

The glycerol is decomposed by glycerol dehydrogenase and converted into dihydroxy ketone and NADH.

Glycerol+NAD(CoA)Dihydroxyketone+NADH

The reaction of NADH or nitrotetrazolium salt, one of the tetrazolium salts, with NADH was directly determined to form L-4-acetyl-5-aminomethyl pyrrole. The spectra were analyzed at 546 nm.

According to this fermentation method, triglycerides can be quantitatively determined. That is to say, glycerol and fatty acid are converted by lipase or esterase, and the content of glycerol ester is calculated by quantitative determination of glycerol. This method has been used in blood tests and so on.

Medicinal Uses of Glycerin

Glycerin, also referred to as glycerol or glycerine, is a colorless, odorless organic liquid derived from fats and oils. It is thick, with a warm, sweet taste. Glycedrin is used in industrial applications, food preparation and in personal care products. It also has medicinal uses, and is often an ingredient in pharmaceuticals.

Eye Disorders

Glycerin is used to treat eye disorders that are caused by increased interocular pressure, such as glaucoma. It can also be used to decrease pressure in the eye before and after ocular surgery, or during a medical eye examination.

Cerebral Edema

Intravenous preparations of glycerin may be used to treat excessive intracranial pressure. Glycerin draws fluid from tissues in the body into the bloodstream, and also acts as a diuretic by preventing water re-absorption in the kidneys. These actions dehydrate the tissues while reducing blood volume, thereby diminishing intracranial pressure.

Vasodialator

Glycerin is a primary constituent of nitroglycerin. Better known for its explosive properties, nitroglycerin is also used as a treatment for angina, a painful condition caused by constriction of the blood vessels in the heart. Nitroclycerin, when taken orally, acts as a vasodialator, rapidly opening the blood vessels in the body to provide greater blood flow and oxygen perfusion to the heart.

Constipation

Glycerin works as a softening agent and lubricant in cases of constipation. A glycerin suppository, inserted into the rectum, melts at body temperature. The glycerin then causes water to be drawn into the colon and rectum, softening the stool and lubricating the bowels, allowing for an easier bowel movement.

Vehicle for Other Medications

Due to its emollient, solvent, sweetening and moisturizing properties, glycerin is frequently used as an ingredient in other pharmaceutical preparations. It is used in tinctures and elixirs, such as Theophylline, which is used to treat asthma. Glycerin is also used in ointments and creams to prevent them from drying out, and can act as a preservative.

How to Cook With Vegetable Glycerin

A sweet, slippery liquid, glycerin forms the backbone of fat and oil molecules. You can get food-grade glycerin, a byproduct of soap making, in bottles at drugstores, health-oriented grocery stores or the baking sections of supermarkets. Glycerin fills a useful role in cakes, cookies, icings candy and fudge by binding water in a form that makes its unavailable to molds, allowing baked goods to stay fresher longer. Glycerin has about 27 calories per teaspoon and is 60 percent as sweet as sugar.

Step 1

Add a few drops of glycerin to recipes for royal icing for cakes and cookies to prevent the icing from drying out and forming a crust. Mix the glycerin with powdered sugar, egg whites and lemon juice.

Step 2

Combine 1 to 2 tbsp. of glycerin with confectioner's sugar, light corn syrup, water and unflavored gelatin to make fondant, a confectioner's sugar frosting often used on wedding cakes. The glycerin keeps the fondant moist and malleable, master baker and teacher James Peterson notes in his text "Baking."

Step 3

Add glycerin along with corn syrup, water, butter and salt to sugar and cornstarch to make saltwater taffy. Stir the ingredients in a saucepan over medium heat. Stir the mixture until it begins to bubble and then let it cook without being disturbed until soft cracks appear, recommends the online site Science of Cooking. Add flavoring and food coloring and pour the mixture onto a shallow cookie sheet to cool.

Step 4

Make nutrition bars by combining cereal or granola and whey protein in a mixer bowl. Add butter and vegetable oil to the bowl, followed by glycerin and water. Roll out the mixture to 3/8 inch, cut into pieces and bake at 400 F for 10 minutes.

Glycerin Ingredients

Glycerin is a highly unique compound that is used to both moisturize your skin and provide anti-freeze for your car. Glycerin is also known as glycerol, glycerine, propane-1, 2, 3-triol, or 1,2,3-propanetriol. This simple chemical compound has a variety of uses in manufacturing, research, and cosmetic products. Often removed from more profitable soaps, and lotions, glycerin is the natural byproduct of the soap making process.

Chemistry

Glycerin is a very short molecule, having the chemical formula C3H8O3. It is composed of three carbon atoms, five hydrogen atoms, and three hydroxy or OH groups.The hydroxy groups are known as the functional alcohol groups, placing glycerin in the alcohol group of chemical compounds (reference 3).

Physical Properties

Glycerin is an odorless, thick, sweet-tasting, syrupy liquid (see reference 2 and 3). Pure glycerin has a specific gravity of 1.26, meaning that it is slightly more dense than water (see reference 2). Glycerin can freeze into a gummy paste and has a high boiling point. Glycerin readily dissolves water and alcohols but not oil-based compounds.

Glycerin is extremely hygroscopic, meaning that it attracts moisture. Exposed to air, pure glycerin will eventually become 80 percent glycerin and 20 percent water. Placed on your tongue, pure glycerin will cause excessive dehydration and result in blistering, as it draws moisture out of your tongue. Glycerin diluted with water, however, will soften skin. It is not clear, however, whether or not it is the hydrogscopic properties of glycerin that cause skin softening or some other mechanism (see reference 1).

Sources

Natural glycerin is found in animal and plant fats. Triglycerides, or fats, are composed of three long hydrocarbon chains linked to a glycerin backbone molecule through the functional OH groups (see reference 3). When broken down, triglycerides form three long hydrocarbon chains and one glycerin molecule. The hydrocarbons provide the fuel, the glycerin is the byproduct.

Similarly, when fats and oils are hydrolyzed to yield fatty acids or soaps, glycerin is formed.

Glycerin is also commercially synthesized from propylene and can be obtained during fermentation as well, although the specific process by which that can be made to occur is proprietary (see reference 2).

Uses

Glycerin is a solvent, food additive, sweetening agent and emollient as well as a demulcent, an agent that forms a soothing film (see reference 2). Glycerin can be used to treat septic wounds and boils, a component of antifreeze, in the manufacture of resins and cellophane, ester gums, plasticizers, dynamite, nitroglycerine, cosmetics, liquid soap, perfume and toothpaste. It also helps keep fabrics pliable, preserves the printing on cotton, and prevents frost from forming on windshields. In research, glycerin is often used as the source of nutrients for fermentation cultures and can act as a preservative as well.(reference 2)

The Effects of Glycerin on Skin

As the "clean beauty" industry grows, customers have started to scrutinize the list of ingredients of their favorite personal care products. Between 2013 and 2017, "natural" product sales grew 2.1 percent — to the tune of $230 million — and it's clear that manufacturers need to be ready to answer questions about what's going into these items.

However, it's not always easy for the layperson to understand what the ingredients in their beauty products truly are. Take, for example, glycerin — this scientific-sounding ingredient might sound alarm bells when it shows up in moisturizers or cleansers, but it's actually an ingredient that does a lot of good for both skin and hair.

What Is Glycerin?

Glycerin, also known as glycerol, might sound like a manufactured ingredient, but it falls squarely into the "natural compound" category. The compound occurs naturally in both plant and animal fats as a component of lipids—which is simply a fancy term for "fats"—and, when it undergoes a process known as hydrolysis, the lipids separate into three fatty acids that form glycerin. However, there's a caveat to this: There is a synthetic form of glycerin out there, which is why reading labels is a great habit to form.

In beauty products, glycerin serves as a humectant, which is a substance the attracts moisture. It pulls the water from deeper skin layers up to the surface to combat dry skin, as well as draws in moisture from the air and slows its evaporation on your skin. Glycerin is the third most common ingredient in cosmetics, according to a 2014 Cosmetic Ingredient Review report.

Is Glycerin Safe?

In short, glycerin is safe. The EWG's Skin Deep Cosmetics Database, a nonprofit that tracks the safety of ingredients in food and cosmetics, gave glycerin a score of two out of 10, meaning it's low-hazard.

The U.S. Food and Drug Administration does not have any restrictions on the use of glycerin as an ingredient in personal care products. However, Canada's Cosmetic Ingredient Hotlist placed glycerin on the "restricted" list in September 2009, noting that manufacturers must provide the exact concentration of the ingredient on the product's label. According to EWG, it was added as a restrict because of possible contamination of glycerine with diethylene glycol (DEG), a potentially toxic ingredient.

Is Glycerin Good for Your Skin?

Through its ability to pull moisture to the surface from both the inner layers of the skin and from the environment, glycerin can work wonders for your skin's outer layer. It's also non-comedogenic, so you don't have to worry about it clogging up your pores and causing breakouts. Glycerin boasts a few other benefits, too, including the ability to strengthen and heal your skin's outermost layer, which also helps keep the skin moist and supple.

Crude glycerol as fuel additive

Glycerol alkyl ether is a good fuel additive, which can improve fuel performance, increase cetane number, increase fluidity, reduce the composition and content of harmful substances in combustion tail gas, and be used as additives for diesel and biodiesel.The application of crude glycerol in this technology can not only utilize the by-product glycerol of biodiesel, but also obtain high value-added glycerol alkyl ether fuel additive. Among them, glycerol tert-butyl ether obtained by the reaction of glycerol with isobutene or tert-butyl alcohol is a promising additive. Adding glycerol tert-butyl ether to diesel fuel can significantly reduce the content of particulate matter, hydrocarbons and carbon monoxide in tail gas.KARINEN et al. investigated the etherification of crude glycerol with isobutene in liquid phase catalyzed by acidic ion exchange resin. It was found that the main reaction in the whole process was etherification. The main products were five kinds of ethers, and the side reaction was oligomerization of isobutene, resulting in hydrocarbons of C8-C16. Moreover, when the molar ratio of isobutene to glycerol was 3:1 and the reaction temperature was 80 C, the selectivity of the reaction was the best. The composition of ether products and the degree of etherification reaction can be controlled by changing reaction conditions.KIATKITTIPONG et al. used fluidized bed catalytic cracking (FCC) gasoline and glycerol as reactants and Amberlyst 16, Amberlyst 15, and beta-zeolite as catalysts to investigate the effect of etherification process on the performance of FCC gasoline. The results showed that the olefin content of etherified gasoline products decreased significantly and the octane number increased compared with the initial FCC gasoline. It was found that beta-zeolite had better catalytic effect and was more suitable as catalyst for etherification reaction when using beta-zeolite and mberlyst 16 as catalysts.

 

Glycerol can also be converted into fuel additives by acetylation and acetalization. RAHMAT etc studied the reaction process and specific characteristics of glycerol converted into fuel additives through etherification, acetylation and acetalization, and applied it to gasoline, biodiesel and diesel oil. The effects of the additives obtained from these reactions were investigated. PRADIMA et al. also summarized the different reaction processes (esterification, etherification, acetylation and acetalization) of glycerol to biofuel additives and related catalysts. It was found that when the fuel additives were mixed with diesel oil, the fuel additives could increase cetane number, improve low temperature fluidity, improve lubricity and reduce the harmful substances in exhaust gas. The effect of quantity. It can be seen that the utilization rate and application value of high value-added fuel additives can be improved by using crude glycerol. However, considering the influence of impurities in crude glycerol on the performance of final fuel, high efficient catalysts can be developed to increase the selectivity and yield of glycerol alkyl ethers. At the same time, unreacted components in crude glycerol can be separated with high efficiency separation and extraction process to avoid secondary pollution to fuel.

Crude glycerol for preparation of 1,2-propanediol and 1,3-propanediol

Crude glycerol, a byproduct of biodiesel, can be used as raw material to prepare a variety of chemical products, such as 1,2-propanediol, 1,3-propanediol, polyester and polyglycerol. They are important chemical raw materials and products, and have a wide range of applications.

1,2-propanediol

1,2-propanediol is an important chemical raw material. The preparation of 1,2-propanediol from crude glycerol is usually carried out by chemical catalytic hydrogenolysis. It was found that the catalytic hydrogenation of glycerol to 1,2-propanediol was catalyzed by Cu/Mgo. The preparation method of the catalyst was investigated. It was found that when the catalyst was prepared by coprecipitation, the activity of the catalyst was the highest, the conversion of glycerol could reach 72%, the selectivity of 1,2-propanediol was 97.5%, and the conversion of glycerol could be further increased to 82% by adding trace NaOH. 1,2-propanediol was synthesized from glycerol by two-step method. First, glycerol was synthesized into acetone alcohol at atmospheric pressure. Then, acetone alcohol was hydrogenated to 1,2-propanediol under the action of copper chromate catalyst. The yield reached 75%. The results show that the technology of catalytic hydrogenation of glycerol to bio-1,2-propanediol has made great progress. However, in order to maintain the high activity of the catalyst, the purity of glycerol is generally high, and further treatment and purification of crude glycerol are needed.

1,3-propanediol

1,3-propanediol is an important intermediate in organic synthesis and an important raw material for the synthesis of polyester PTT (polypropylene terephthalate). With the continuous promotion of biodiesel technology, the production of 1,3-propanediol from crude glycerol by biological method has attracted extensive attention of researchers all over the world. Several strains of 1,3-propanediol fermentation have been reported in the literature, such as Klebsiella pneumoniae, Lactobacillus brevis, Citrobacterfreundii, Clostridium butyricum, Clostridium pasteurianum and so on. Hu Qiulong et al. fermented 1,3-propanediol from glycerol, a by-product of biodiesel, Klebsiella spp. as a strain. The production efficiency and economic feasibility of glycerol with different purity were investigated. The results showed that the conversion rates of 1,3-propanediol from refined glycerol (purity & gt; 98%), crude glycerol A (purity 83%), crude glycerol B (purity 78%) and crude glycerol C (purity 68%) were respectively. The cost of 1,3-propanediol in crude glycerol A and B production units is lower than that of refined glycerol and crude glycerol C through rough economic evaluation, which is 52.38%, 48.08%, 45.22% and 39.95%. MARIA et al. improved Clostridium butyricum by metabolic engineering. A recombinant strain DG1 was obtained. It was found that when glycerol was used as substrate, 1,3-propanediol could be produced efficiently by fermentation, and it could be operated continuously for a long time at a high volumetric yield of 3g/(L.h). Using Klebsiella neumoniae ATCC15380 as strain, crude glycerol as byproduct of biodiesel as raw material, ANAND et al. fermented to produce 1,3-propanediol. Among them, the yield of propanediol can reach 56g/L, the molar conversion rate of glycerol is 0.85. The purity of 1,3-propanediol can be obtained by separating and purifying the fermentation broth, and PTT products can be successfully prepared from it to meet the requirements of polymerization grade. Biological production of 1,3-propanediol has the characteristics of mild reaction conditions, low environmental pollution and renewable resources. However, there are still some difficulties in its large-scale industrialization. The main limiting factors are the high cost of raw materials and the high cost of separation and purification process. The production of 1,3-propanediol from crude glycerol is an effective way to reduce the cost of raw materials.

The Effect of Glycerol Supplements on Performance of Athletes and Sedentary Subjects

Glycerol is produced from glucose, proteins, pyruvate, triacylglycerols and other glycerolipid metabolic pathways and it is a junctional metabolite in numerous pathways. In particular, the metabolic importance of glycerol is based on the deprivation of glucose under aerobic and anaerobic conditions. In humans, gluconeogenesis, glucose biosynthesis from non-carbohydrate precursors, mainly occurs in the liver and kidneys. While under normal health and dietary conditions, gluconeogenesis from glycerol accounts for less than 5% of glucose production; however, it appears that, after 62–86 hours of starvation, more than 20% of such production is derived from glycerol metabolism. During prolonged fasting, glycerol is the only source for gluconeogenesis, since glycogen reserves are depleted within two fasting days. This capacity to divert glycerol turnover into glucose production is an important evolutionary adaptation and allows for survival during undesirable conditions.

Glycerol is a safe agent that does not approach toxic levels when administered orally in doses of <5 g/kg body weight. Glycerol, which can be ingested in comparatively large amounts, accumulates in body fluids, except for those of the brain and eyes, increasing osmotic pressure and the total volume of water in the body. Glycerol could be used as an energy substrate in nutrition, and could significantly contribute to the energy yield during exercise. Considering its energy substrate function, glycerol could efficiently improve athletic performance. Glycerol’s osmoprotective solute quality can be used to improve physical endurance. The reduction in serum blood osmolality and the effects on ionic gradients caused by glycerol ingestion delay fatigue; therefore, endurance and athletic performance are improved. For a long time, the combined ingestion of glycerol and liquid has been used to increase body water volume, thus maintaining hydration by reducing the kidney’s’ water elimination rate. Glycerol could, therefore, play a very important role in thermoregulation, resistance to high temperatures and endurance in physical activities.

When consumed orally, glycerol is rapidly absorbed and distributed between body fluid compartments before being slowly metabolized via the liver and kidneys. When consumed in combination with a substantial fluid intake, the osmotic pressure enhances the retention of this fluid and the expansion of various body fluid spaces. Typically, this allows fluid expansion or retention by reducing the urinary volume. It’s reported that this fluid retention volume is in the range of 300–730 ml. It’s also reported that the use of glycerol increases blood osmolality and, when accompanied by large amounts of water (1500–2000 ml, or 26 ml/kg body weight), provides an osmotic drive that augments the retention of large quantities of water, which would otherwise be eliminated by the kidneys.

Glycerol, a naturally occurring metabolite, has been shown to be a safe and effective hyperhydrating agent. Glycerol combined with water hyperhydration increases total body water when compared with water hyperhydration alone. Different authors have shown conflicting results when assessing the effect of pre-exercise glycerol administration on subsequent performance functions. Several researchers have shown positive effects on performance after glycerol ingestion. For example, it has been suggested that glycerol-induced hyperhydration increases exercise performance. Similarly, it has been demonstrated that glycerol ingestion increases, exercise tolerance in terms of time by approximately 24%. Glycerol ingestion increases the length of time that can be spent exercising because of the improvement in physical endurance. In addition, heart rate during exercise appears to be significantly lower after glycerol intake. Despite these findings, others have shown no benefits from pre-exercise hyperhydration with glycerol compared with hyperhydration with water alone. Total body glycerol disposal can be divided into oxidation and gluconeogenesis. Most of the glycerol is turned into glucose in the liver by gluconeogenesis and the remainder is oxidized. The glucose produced is circulated in the blood stream and what is not required is converted into glycogen in the liver and muscles. Muscle glucose decomposes into pyruvic acid which supplies energy for exercise.

What are the benefits and disadvantages of glycerin for the skin

Glycerol has the advantages of moisturizing and moisturizing, moisturizing the skin and preventing skin cracking. Correct use of glycerol skin care can play a very good moisturizing and skin care effect. Glycerol is not harmful, but we need to pay attention to the use of the environment and concentration, some glycerol need to be diluted before it can be used, and direct use is slightly irritating to the skin.

Glycerin for Skin Benefits:

1.Moisturizing ,glycerin is very suitable for people with dry skin. Glycerin rubbing on the skin can moisturize dry skin. Then glycerin will form a protective film on the skin surface, which will lock up the moisture in the skin and reduce the loss of water. And glycerol also absorbs moisture from the air itself, keeping the skin moist for a long time.

2.Protective benefits

When glycerin is applied to the face, an invisible protective film will be formed on the skin surface, which will isolate the outside air from the skin and protect the skin against the invasion of the outside environment. So before going out in winter, apply glycerin on bare skin to protect skin.

3.Frost crack prevention

There is another advantage of using glycerin in winter, that is, to prevent skin frost cracking, winter hands and feet prone to chilblain, after the weather turns cool, stick to the use of glycerin every day, can play a role in preventing chilblain. If the lips are easy to crack, then it can be applied to the lips, just be careful not to eat.

Notes for glycerol skin care:

1.Attention should be paid to air humidity in winter when skin is dry. Glycerol can absorb water and keep skin moist and moist for a long time. But this method is limited to the south where the air is wet. If the air is dry in the north, glycerol can't absorb moisture from the air, and it will absorb moisture from the skin, so the skin will get drier and drier. To use glycerin, look at the air humidity of the day above 50, then you can rest assured that the use of glycerin.

2.Glycerol skin care should not be directly applied glycerol, although it can moisturize the skin, but because of the high concentration of glycerol, directly applied to the skin may bring some irritation, and too high concentration of glycerol directly applied to the skin, strong water absorption may also absorb water from the skin. So before using glycerin, it's better to dilute it with water.

3.Pay attention to the fact that glycerol is not oil, but the skin will feel more oil after applying glycerol, so glycerol is more suitable for people with dry skin, if it is oily skin, then the use of glycerol will easily make the skin greasy and uncomfortable, so the use of glycerol is best based on their skin.

 

The possibility and prospect of using glycerol as an energy feedstuff source for pigs

Corn is the main source of energy feeds for pigs. In recent years, both the increasingly rising price and also the tense supply of corn have influenced the development for the pig industry very severely. In order to accommodate with the states, people have been looking for alternative energy feeds actively, and have also conducted much extensive research. Among them, the possibility and prospect of using glycerol (a by-product of biodiesel production) as a source of energy feedstuff proposed by some countries have brought attention from the world.

According to statistics, the capacity of biodiesel under construction in China is up to 3 million t/ year. This means that large amounts of glycerol by-products will be produced worldwide. With the increase of biodiesel production, the quantity of its by-product glycerol also have increased accordingly, providing sufficient material base for the exploitation of glycerol.

Glycerol, a small molecule by-products, is a colorless, odorless, clear liquid, released during the process of biodiesel production. For livestock, fat intake from the fodder will be digested into glycerol and fatty acids in the digestive tract, which will be obtained and finally stored in the adipocytel as the most economical storage form in the body of livestock. And this could convert into heat energy when needed. Therefore, glycerol is one substance of the animal physiological system. Using glycerol as energy feed for livestock has become one of the hot research topics in this way for many countries.

 

Due to its small molecular weight and molecules, glycerol is easily absorbed by the intestinal tract of livestock via simple diffusion. In the metabolic pathway, glycerol is used for energy production.

The latest study shows that the metabolizable energy (ME) of glycerol is close to its total energy (GE). This indicates that glycerol has a higher digestibility. With proper content, glycerol could improve the quality of pelleted feed, reduce both the energy costs in the pelletizing process, and also the powder in fodder and additives.

Some researchers have pointed out that because glycerol is sweet, it can improve the palatability of fodder.

 

Iowa State University conducted a series of animal experiments on using glycerol as an energy feed instead of corn. And its results shows that effect of glycerol is comparable to that of corn, with a promising prospect. Dutch Dr. Jannes Doppenberg thought glycerin would be a popular nutritive material as it's going to be a common ingredient, while other bio-fuel byproducts such as DDGS and rapeseed meal/press cake are low-energy and starch-deficient raw materials. William Dozier, an animal scientist at the USDA's agricultural research service (USDA-ARS), has pointed out that glycerol can be used as an alternative source of energy in fodder to reduce fodder costs, from a nutritional standpoint. A series of experiments confirmed that glycerol had the same energy value as corn.

Although using glycerol as an energy feed for pigs still with many problems that need to be further studied has not been commercialized on a large scale, the current researches and future development trend indicates that using glycerol as a source of energy for pig fodder has a great foreground.