Sorbitol in Food Products

What is Sorbitol?
Use and Applications of Sorbitol in the Food Industry
Product Examples
Properties of Sorbitol
Typical Formulations
Sorbitol Formulation Considerations
Safety and Regulatory Considerations
Fun Facts About Sorbitol
Additional Resources

Sorbitol, known by its IUPAC name as D-glucitol, is a sugar alcohol frequently used as a sweetening agent, moisture stabilizer, and texturizer in various food products. In this article, we’ll delve into the chemistry of sorbitol and the functional attributes that make it a popular choice in the food industry.

What is Sorbitol?

Sorbitol is a type of polyol, which means it is a sugar alcohol that is derived from the sugar glucose. It is a white, crystalline powder that is soluble in water. Sorbitol is often used as a sugar substitute for individuals with diabetes or those following a low-carbohydrate diet. It provides sweetness without causing a significant increase in blood sugar levels. Sorbitol is also commonly used as a bulking agent in various food products, helping to add volume and texture. It is considered safe for consumption by regulatory authorities when used in moderation.

Source: Wikipedia

Sorbitol is a six-carbon sugar alcohol with the molecular formula C₆H₁₄O₆. It is derived from glucose through a process called reduction, where one of the aldehyde groups in glucose is converted to a hydroxyl group. This reduction reaction is catalyzed by an enzyme called aldose reductase. Sorbitol is an isomer of mannitol, another sugar alcohol; the two differ only in the orientation of the hydroxyl group on carbon 2.

How is Sorbitol Produced?

Sorbitol can be produced naturally, via fermentation, and also synthetically. Here’s a breakdown of the different methods of production:

Natural Sources

Sorbitol is found naturally in blackberries, raspberries, strawberries, and other fruits such as apples, apricots, avocados, cherries, peaches, and plums.

Fermentative Production

Microbial fermentation is another method used for sorbitol production. Certain strains of bacteria, such as Zymomonas mobilis and Escherichia coli, can ferment glucose into sorbitol. This process involves genetically modified microorganisms efficiently metabolizing glucose to produce sorbitol as a metabolic byproduct. Synthesis of sorbitol takes place by catalysis of glucose via NADP-dependent sorbitol-6-phosphate dehydrogenase (S₆PDH).

In genetically engineered Lactobacillus casei strain expressing a sorbitol-6-phosphate dehydrogenase gene within the lactose operon, the L-lactate dehydrogenase gene inactivation led to increased sorbitol production [1].

Synthetic Production

Chemical synthesis involves the conversion of glucose, typically derived from corn or wheat, into sorbitol using chemical reactions. The process requires hydrogenation, where glucose is hydrogenated in the presence of a catalyst, such as nickel or platinum, under specific temperature and pressure conditions. This reaction converts glucose into sorbitol [2].

Use and Applications of Sorbitol in the Food Industry

Sorbitol serves as a multifunctional ingredient in the food industry. As a sweetener, it provides approximately 60% of the sweetness of sucrose, making it a preferred choice in sugar-free and reduced-calorie products, especially for those tailored for people with diabetes. Beyond its sweetening properties, sorbitol acts as a humectant, attracting and retaining moisture, which helps maintain freshness and extend the shelf life of food products. Its hygroscopic nature also lends a smooth texture by preventing sugar crystallization in foods, especially candies and syrups. Furthermore, as a bulking agent, sorbitol contributes volume without excessive sweetness, and as a cryoprotectant, it ensures the palatability of frozen foods by preventing the formation of large ice crystals. These versatile characteristics make sorbitol a staple in various food applications, from confectioneries to baked goods.

Here’s a breakdown of some of the more common functions of sorbitol in food products:

Function	Role
Bulking Agent	Adds volume to food products without significantly adding calories
Emulsifier	Helps to stabilize mixtures of two immiscible liquids, such as oil and water
Stabilizer	Helps to prevent unwanted changes in the texture or consistency of food products over time
Thickener & Texturizer	Helps to thicken the consistency of food products
Humectant	Helps retain moisture in food products

Product Examples

These are some of the most common products sorbitol is found in:

Type	Examples
Bakery	Cake, Pastry, Cookies, Bread
Confectionery	ChewingGgums, Soft Chews, Gummy Bears, Crystal Candies
Dairy	Yogurt, Ice Cream
Beverages	Juices, Soft Drinks
Convenience	Jams, Jellies, Cereals, Fruit Preserves

Properties of Sorbitol

Molecular Weight	101
Melting Point	101℃
Heat of Solution	-111 J/g
Physical Form	Powder, Crystals (Granules) & Syrup
Solubility (25℃)	235 g/100g Water
Viscosity (1% w/v, 25℃)	5.0 cP
Calorific Value	2.6 Cal/g
Relative Sweetness w.r.t Sucrose	50-60%
Glycemic Index	~9
Shelf Life	24-36 months
GMO Status	GMO/Non-GMO
Claims *Subject to product claims	Kosher, Halal, Dairy-free, Sugar-free, Non-cariogenicPlant based, Organic, Non-GMO, Natural, Allergen-free* etc.
Storage Requirements	Cool, dry, dark place < 40℃)
Specific Rotation	Optically inactive

Typical Formulations

Candy

Here is an example formulation table of clear candy with sorbitol with the weight composition of the ingredients.

Ingredient	Composition
Sorbitol powder	300 g
Water	15 g
Mixed sesame seeds	–
Natural lemon essence	2 g
Menthol	0.3 g

Gradual cooling of molten sorbitol in a specific temperature range for a particular time, under a certain cooling rate condition under strict temperature control, has helped obtain clear hard candy. No unevenness or roughness on the surface was observed.

Source: Google Patents

Chewing Gum

Here is an example formulation table of chewing gum with sorbitol with the % composition of the ingredients.

Ingredient	% Composition
Gum base	20.7
Sugar	51.5
Sorbitol	2.7
Corn syrup	13.2
Dextrose monohydrate	10.1
Glycerin	1.2
Spearmint flavor	0.6

A possible explanation for using molten sorbitol is that it is modified from a crystalline state to a more amorphous state, which may allow it to act as a gum plasticizer or softening agent.

Source: Google Patents

Mango Squash

Here is an example formulation table of synthetic mango squash with sorbitol with the weight composition of the ingredients.

Ingredient	Composition
Guar gum	8 g
Sorbitol	700 ml
Citric acid	3.75 g
Sodium citrate	1 g
Sucrose acetate iso-butyrate	1 ml
Mango flavor	1 ml
Mango color	0.25 g
Sodium benzoate	1 g

Sorbitol was used here as the sole sweetener in the squashes for consumption of diabetic patients.

Source: Aup.edu

Sorbitol Formulation Considerations

Stability

Sorbitol is generally stable concerning heat, light, and oxidation. D-Sorbitol showed a degradation starting at 200°C [3].

Physical Forms

Sorbitol exists in two forms: a crystalline and a liquid form. The crystalline structure is a white, odorless powder with a sweet taste. It has a melting point of around 95-97°C. The liquid form, or sorbitol solution, is a viscous, colorless liquid with a sweet taste. It is commonly used in liquid medications, syrups, and oral care products.

Sensory Properties

Sensory Profile

Physical Form	Liquid, powder, crystals
Color	White
Taste	Sweet (towards sucrose)
Odor	Odorless

Sweetness Profile

Taste Profile	Sweet taste with a smooth mouthfeel
Aftertaste	No aftertaste
Off-taste	No off-taste
Taste & Appearance	Sweetness appears quickly and has a shorter persistence

Use as a Sugar Substitute

Sorbitol is a sugar alcohol commonly used as a sugar substitute.

Benefits of usage of sorbitol as a sugar substitute

Sorbitol provides sweetness and bulk, unlike the artificial non-caloric sweeteners viz. acesulfame K, neotame, aspartame, and saccharin.
It is an excellent humectant and texturizing agent.
It does not contribute to dental caries.
It may be helpful to people with diabetes.

The following table comparing the properties of sorbitol with other sugar alcohols can play a pivotal role in understanding the suitable sugar substitute in any formulation.

Sugar alcohol	Calorific value (kcal/g)	Relative Sweetness (to Sucrose)	Glycemic index
Maltitol	2.1 Cal/g	80-90 %	~35
Erythritol	0.2 Cal/g	60-70 %	~0
Xylitol	2.4 Cal/g	80-100 %	~13
Sorbitol	2.6 Cal/g	50-60 %	~9
Sucrose	4.0 Cal/g	100%	~65

A detailed comparison of all sugar alcohols can be seen here.

Limitations of usage of sorbitol as a sugar substitute

High caloric value
Lower relative sweetness with sucrose compared to xylitol and maltitol

Metabolism, Absorption & Excretion

Absorption	Sorbitol is slowly absorbed by passive diffusion in the small intestine. After oral administration, it increases osmotic pressure in the bowel by drawing in water and is thus an osmotic laxative [4].
Metabolism	– NAD-linked sorbitol-6-phosphate dehydrogenase (EC 1.1.1.140) converts sorbitol 6-phosphate to fructose 6-phosphate [5]. – Bacterial sorbitol fermentation in the large bowel is associated with increased flatulence and abdominal cramping. – The digestibility of the other nutrients is also reduced due to the osmotic load caused by the polyols in the small intestine [6]. – Acute oral administration of sorbitol does not affect glucose homeostasis, which is only slightly disturbed by a large intravenous load of sorbitol [7].
Excretion	Sorbitol will either be excreted in the urine by the kidneys or metabolized to carbon dioxide and dextrose [4].

Effect on Properties of Food Products

As a food additive, Sorbitol exerts some effects on the food products it adds.

Functional Properties

Freezing Point Depression	In terms of its effect on freezing point, sorbitol can lower the freezing point of a solution. This is because sorbitol molecules disrupt the formation of ice crystals, preventing the solution from freezing at its average temperature. Sorbitol exhibited a more significant freezing point depression than reducing sugars [8].
Shelf-Life Extension	– Sorbitol can be used as an osmolyte to extend the shelf life of perishable goods. – The postharvest quality of ivy gourd was effectively extended by mannitol and sorbitol for up to 10 days without significantly affecting their phytochemical and physiological attributes [9].

Safety and Regulatory Considerations

FDA Information	Sorbitol is generally recognized as safe (GRAS) by the U.S. Food and Drug Administration (FDA) when used per good manufacturing practices [10].
EU Information	In the European Union, sorbitol is regulated as a food additive under the European Food Safety Authority (EFSA). It is assigned the E number E420 and is approved for use as a sweetener, humectant, and stabilizer in various food and beverage products.

Health Effects of Sorbitol

Unlike other simple sugars, sorbitol is metabolized slowly in the human body, leading to a more gradual rise in blood sugar levels. This makes it a preferable alternative to sugar for individuals with diabetes or those monitoring their blood sugar levels.

Polyols (sorbitol, mannitol, xylitol, maltol, maltitol, and erythritol) have known laxative properties. However, quantities more significant than 50 g daily were laxative. A total of 25 g daily in two doses caused no laxative effect. This effect was presumably due to the relatively slow rate at which sorbitol was absorbed from the small bowel [14].

Sorbitol can cause gastrointestinal symptoms (gas, urgency, bloating, abdominal cramps) dose-dependently [15]. Sorbitol is frequently overlooked as a potential cause of diarrhea [16].

Identification Numbers

IUPAC Name	(2R,3R,4R,5S)-hexane-1,2,3,4,5,6-hexol
CAS Number	50-70-4
EC Number	200-061-5
INS No. (Food Additive)	INS 420
E Number (Food Additive)	E 420

Acceptable Limits or Maximum Usage

The FDA prescribes the maximum level of usage of sorbitol for the following categories of foods [10].

Category	Usage
Hard candy & cough drops	99%
Chewing gum	75%
Soft candy	98%
Non-standardized jams and jellies	30%
Baked goods & baking mixes	30%
Frozen dairy desserts	17%
All other foods	12%

As per the FDA, food whose reasonably foreseeable consumption may result in a daily ingestion of 50 grams of sorbitol shall bear the statement: “Excess consumption may have a laxative effect.” [10].

Fun Facts About Sorbitol

Sorbitol is one of the compounds discovered on Mars! In 2015, the Curiosity Rover detected the presence of various organic compounds on the red planet, and sorbitol was among them.
Unlike regular sugar, sorbitol doesn’t lead to cavities. This quality makes it a popular ingredient in sugar-free gum and toothpaste. Bacteria in the mouth can’t readily convert sorbitol into acid-producing decay catalysts as they do with sucrose.
Besides its extensive use in the food industry, sorbitol is also used in cosmetic products like lotions and creams due to its excellent moisturizing properties.
Sorbitol was once used as a fuel in solid rocket propellants. When combined with a powerful oxidizer, it can rapidly combust.
In medical settings, sorbitol is sometimes used as a laxative. It works by drawing water into the large intestine stimulating bowel movements.
Sorbitol was first discovered by a French chemist named Boussingault in 1872. He isolated it from the fresh juice of mountain ash berries, which is why its name is derived from the genus of these trees, Sorbus.