Detergent enzymes liquid formulations

Until the end of the sixties enzyme products such as the detergent proteases were just powder products. Today very few powdered-enzyme products remain. All detergent enzyme products from the larger enzyme suppliers arc either hquid formulations or granulated and further protected by coatings. Today formulation techniques really have become a science with MAC-values in production facilities of 10-100 nanogram/m air. It is further recommended that the use of such safe enzyme products shall be planned such that the liquid enzyme product is not spilled and allowed to diy and aerosol formation shall be prevented. With these simple rules in mind, industrial enzymes arc very safe. 

It is sometimes possible to add properties in liquid formulations that provide additional functions. Examples in development or in commercial use as of 1993 include microencapsulation (qv) of enzymes for protection against bleach when dispersed in a liquid detergent addition of certain polymers to protect the enzyme after it has been added to liquid deteigents (32), or to boost activity in the final application addition of surfactants or wetting agents,... 

Detergent Enzymes Table 3 Example of heavy-duty liquid detergent (HOLD) formulation ... 

The final formulation of liquid detergent enzymes includes addition of stabilizers, antimicrobial substances, and glycols. This is followed by a final polish filtration to provide a clear liquid. If the enzyme broth is slated for dry product, the concentrate can either be stored for later use or applied directly for granulates. As with fermentation and downstream processing, formulations are often kept as closely guarded trade secrets in the biotechnology industry, and few publications on new approaches or new technologies are available in the literature. 

Enzymes are an increasingly important component in detergent formulations, both in terms of effectiveness and as a means of product differentiation. The primary types of detergent enzymes are protease, amylase, lipase, and cellulase all are derived from bacterial and fungal sources. Enzyme activity is subject to various forms of chemical and physical degradation, problems that are particularly acute in liquid formulations, where the enzymes cannot be physically isolated from the harmful effects of surfactants and bleaches. 

Liquid enzyme products have various applications such as additives in dishwasher detergents and animal feed (PPLA, post-pelleting liquid application). The formulation of enzymes in liquid form can be challenging as the liquid forms are more dynamic systems compared to solids because of the presence of water, and for this reason additional stabilizing agents are required in liquid formulations. 

In structured liquid detergents, a longer alkyl chain is more desirable, whereas in unstructured liquid detergents, shorter alkyl chains ( C ) are desirable for increased solubility. Potassium and amine salts are preferred to improve solubility and phase stability of the liquids. LAS has a disadvantage in liquid enzyme-based formulation due to enzyme destabilization. 

The development of much more complex, efficient, and sophisticated detergents (e.g., by introducing bleaching systems) has increased the demand for robusmess of the enzyme formulation. Furthermore, the popularity in recent years of heavy-duty liquid detergents has pressed for the development of stable liquid formulations of enzymes for this segment. Finally, the majority of the more sophisticated detergents today have more than one enzyme present—up to four have been described—and as proteases normally are always present, it can sometimes create challenges. 

Liquid formulation in this context means nonsolid formulations. The vast majority of liquid formulations are based on water with a varying degree of other components present, although liquid nonwater formulations of enzymes have been described. The most important of the issues listed in Table 27.2, when working with liquid formulations, is the stability of the formulated enzyme product as well as the final liquid detergent. A comprehensive overview of the stability issues of enzymes in detergents is given in Ref. 11. Stability can be divided into enzymatic, physical, and microbial stability. 

In liquid detergents, enzyme solutions are simply mixed with the product. Again, they are introduced in the composition at the end of the formulation to avoid temperatures above 30—40°C and pH s below 7 or above 10. 

Novozymes supplies the proteases for liquid detergents to the detergent manufacturer as a stable liquid enzyme formulation from which typically less than 2%(w/w) is added to the liquid detergent composition. The limited solubility of boric acid thus prevents Novozymes from supplying the detergent manufacturer with a liquid enzyme formulation with a built-in boric acid stabilization system. 

Tetrahedral borate or boronate complexes have been shown to be involved in enzyme inhibition. Serine proteases were proposed to be inhibited by boric acid [6], and simple borates have been patented as protease stabilizers in liquid detergent formulations [7, 8]. 

Stoner, M.R. Dale, D.A. Gualfetti, P.J. Becker, T. Manning, M.C. Carpenter, J.F. Randolph, T.W. Protease autolysis in heavy-duty liquid detergent formulations Effects of thermodynamic stabilizers and protease inhibitors. Enzyme and Microbial Technology 2004, 34, 114—125. 

Enzymes have become integral components of most liquid detergent compositions as they continue to play an increasing role in the stain removal process. This has come about due to many recent advances in enzyme technology and has resulted in more efficient and effective strains. The ability of these enzymes to target specific classes of stains can provide the formulator with the flexibility to tailor the development of products for consumers with different requirements and preferences. In addition, enzymes are especially effective when the liquid detergent is used as a prespotter. 

While enzymes have played a role in powder detergents in the U.S. market over the years, more recently they have started to emerge as additives in LADD formulations. Both proteases and amylases have appeared in LADDs in spite of the fact that, unlike powders, oxygen bleaches could not be incorporated for stain removal. They first appeared in bottled liquid/gel products in 2000 in the U.S. These were introduced as premium products, with dual enzymes, and captured about 5% of the total automatic dishwashing market. 

The new liquid laundry detergents, with no phosphates, have developed a use for alkanolamines. In nonenzyme formulations, they contribute alkalinity, pH control, and enhanced product stability. In enzyme products, alkanolamines contribute to the stability of the enzyme in water solutions (107). 

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