Sorbitol A Multifunctional Polyol in Food, Pharma, and Biotechnology
Introduction
Sorbitol, chemically known as glucitol, is a sugar alcohol (polyol) widely used as a low-calorie sweetener and humectant in various industries. Found naturally in many fruits, sorbitol is produced industrially by hydrogenating glucose. Its versatile physical and chemical properties make it valuable in food, pharmaceutical, cosmetic, and plant biotechnology applications.
Chemical Profile
- Formula: C₆H₁₄O₆
- Molecular Weight: 182.17 g/mol
- Sweetness: About 60% as sweet as sucrose
- Energy Value: 2.6 kcal/g
- Solubility: Highly soluble in water
Sorbitol has six hydroxyl groups that allow it to attract moisture, stabilize formulations, and act as a plasticizer.
Natural Occurrence and Biological Role
Sorbitol occurs naturally in:
- Apples
- Berries
- Plums
- Cherries
In plants, sorbitol functions as:
- A primary photosynthetic product
- A carbon transport molecule
- An osmoprotectant under drought stress
In humans, sorbitol is a metabolic intermediate, slowly absorbed and converted to fructose in the liver.
Industrial Production
Commercially, sorbitol is produced via catalytic hydrogenation of glucose:
Glucose + H₂ → Sorbitol
Nickel catalysts are used under high temperature and pressure. Research is ongoing into microbial production using bacteria like Zymomonas mobilis for greener alternatives.
Applications
1. Food Industry
Sorbitol is a key ingredient in:
- Sugar-free chewing gums and candies
- Diabetic-friendly foods
- Ice cream and baked goods
It improves texture, retains moisture, and doesn’t promote tooth decay.
2. Pharmaceuticals
Sorbitol serves as:
- A sweetener in syrups and suspensions
- A laxative (osmotic effect)
- A tablet binder and viscosity modifier
3. Personal Care and Cosmetics
Used in:
- Toothpaste and mouthwash (as a humectant)
- Lotions and creams (for moisture retention)
4. Industrial Uses
Precursor in the manufacture of:
- Vitamin C (ascorbic acid)
- Polyurethanes and surfactants
- Synthetic resins and plastics
5. Plant Tissue Culture
In biotechnology, sorbitol is used as:
- A carbon source in media
- A conservant for in vitro storage
- An osmoticum to slow plant growth for conservation
Studies, especially on Citrus aurantifolia, have shown sorbitol’s role in maintaining viable plant cultures under low metabolic conditions.
Biological Significance and Metabolism
In Humans
- Metabolized in the liver to fructose
- Has a low glycemic index, making it safe for diabetics
- Excess consumption may cause laxative effects, including bloating or diarrhea
In Plants
- Acts as an osmoregulator
- Maintains cell turgor under drought
- Enhances stress tolerance mechanisms
Advantages and Limitations
Advantages
- Suitable for diabetic foods
- Does not cause dental cavities
- Enhances shelf life
- Stable under heat and acidic conditions
Limitations
- Laxative in large quantities
- Not as sweet as sucrose
- Can cause bloating or gastrointestinal discomfort
Health and Safety
Sorbitol is recognized as safe (GRAS) by the FDA. However, people with sorbitol intolerance or hereditary fructose intolerance (HFI) must avoid it due to metabolic complications.
Recent Innovations
- Green production methods using biocatalysts
- Microbial fermentation technologies
- Use in cryopreservation and germplasm storage
- Novel formulations in sugar-free therapeutics
Conclusion
Sorbitol is a multifunctional compound valued for its sweetening ability, moisture-retention properties, and biological compatibility. Its use spans food and pharmaceutical formulations to advanced applications in biotechnology, especially plant conservation. With continued research into sustainable production and novel uses, sorbitol remains essential in science and industry.
References
- FDA. (2022). GRAS Notice for Sorbitol. https://www.fda.gov
- Kwon, H., & Kim, J. (2014). Sorbitol production by glucose hydrogenation. Korean J Chem Eng, 31(2), 199–204.
- Martindale, W. (2020). The Complete Drug Reference (38th ed.). Pharmaceutical Press.
- Shukla, S., & Singh, N. (2019). Sorbitol in plant tissue culture. J Plant Res, 132(1), 1–12.
- Paunescu, A. (2009). Biotechnology for plant conservation. Romanian Biotechnological Letters, 14(1), 4095–103.
- Shibli, R.A., et al. (2006). In vitro conservation and cryopreservation. World J Agric Sci, 2(4), 372–82.
- WHO. (2021). Food Additive Specifications: Sorbitol. https://www.who.int
- Lai, R., & Lai, S. (2019). Pathogen-free plants using tissue culture. Crop Improvement, 73–116.
- Riley, J.M. (2012). Gibberellic Acid for Fruit Set and Seed Germination. CRFG Journal.
- Tien, L.H., et al. (2020). Auxin effects on clonal propagation. Plant Cell Biotechnol Mol Biol, 21(55–56), 113–120.
