Controlled release of automatic dishwashing detergent ingredients

Fenton, Thomas Mark (2023). Controlled release of automatic dishwashing detergent ingredients. University of Birmingham. Ph.D.

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Abstract

Dishwashers are a ubiquitous appliance in almost every modern household in the United Kingdom. Millions of people everyday load their dishwasher with their dirty crockery and glassware, insert a tablet or pouch and run a washing cycle without consideration of if the cleaning performance of their dishwasher could be improved. The familiar compressed powdered or liquid detergent capsules have been a mainstay of the supermarket aisles for decades, with only minor improvements made in their formulation characteristics and performance in this time period. The primary issue which still plagues current formulations is the inherent incompatibility between several of the detergent ingredients, caused by mixing harsh chemical reagents such as bleach, with sensitive ingredients such as non-ionic surfactants and enzymes. Current formulations offer only rudimentary ways of separating these incompatible ingredients in storage and during the wash cycle. The focus of this thesis was to create a way of encapsulating these ingredients such that good segregation would be achieved during storage and in the wash cycle, whereby the release profile of the ingredient would be well-understood and tuneable to the consumer requirements. To carry out this task, a variety of hydrocolloid gels were investigated for their ability to encapsulate and selectively release an enzyme and surfactant which are sustainable, renewable and non-toxic materials. It was shown that both kappa carrageenan and low acyl gellan with tamarind seed xyloglucan could form suitable gels for this purpose. The encapsulation of sodium hypochlorite bleach was more difficult due to its low molecular weight giving a consequentially high diffusivity, and its harsh chemical nature. Hence, paraffin wax and soy wax were successfully employed as chemical resistant encapsulation materials with very low porosity. Three different techniques were employed to encapsulate the bleach within wax capsules, the most efficient and effective of these was a novel method “freeze dropped” method proposed in this thesis which produced wax capsules which were more stable to leakage and were produced at a higher encapsulation efficiency than other tested methods previously proposed in literature.

In summary this thesis proposed various methods and materials for the encapsulation and thermoselective release of automatic dishwashing detergent ingredients, as well as exploring the nature of any interactions between the detergent ingredients and the encapsulation materials. It is possible that the work proposed in this thesis could be used to develop a temperature-activated detergent capsule. Additionally, work regarding the interaction between detergent ingredients and encapsulation materials, particularly those concerning biopolymer gels, could be useful in other fields where mixtures of these ingredients are also common, such as food, cosmetics and pharmaceuticals. And finally, the novel gel formulation of low acyl gellan gum with tamarind seed xyloglucan could see potential as a gelatine replacement in the food and pharmaceutical industry due to its high mechanical strength combined with its low melting point, which is a rare property in biopolymer gels.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):