Text Rianne Lindhout
Melanoidin from coffee grounds is an excellent alternative for animal proteins as a stabiliser and antioxidant in various foods. Jilu Feng obtained a PhD on the subject last year and recently published two articles in Food Hydrocolloids and the Journal of Agricultural and Food Chemistry with colleagues.
From peanut butter and ice cream to dressings and mayonnaise and from cream and lotions to sprays and foams: all of these products contain a substance that keeps the mixture mixed. These mixtures are made up of both oily and watery components, which do not mix under normal circumstances. An emulsifier solves this issue. The molecules in an emulsifier have one side that attracts water and one side that repels it. In foodstuffs, egg yellow and the lactoproteins in dairy products serve as emulsifiers.
Jilu Feng and her colleagues in WUR’s Food Quality and Design group and the Food Process Engineering group wondered whether coffee melanoidin could also serve as an emulsifier. Feng: ‘These melanoidins are safe and are already consumed by coffee drinkers, and can easily be extracted from coffee grounds. They could offer a natural and sustainable alternative to meet the increasing demand for plant-based products.’
Flasks with mixtures
Feng made flasks with a mixture of oil and water and added varying amounts of coffee melanoidins. She then checked the stability of the mixtures for four weeks. ‘It worked. A very interesting fact is that higher concentrations of the substance resulted in emulsion gels, which can be used to change the texture of an emulsion to suit one’s wishes.’
Researchers saw the substance also works well as an antioxidant during a follow-up study. That is relevant to foods with many unsaturated fatty acids, such as margarine and mayonnaise. These fatty acids are prone to oxidise when exposed to oxygen atoms, resulting in loss of quality, shelf-life, nutritional value and flavour.
Coffee-flavoured strawberry ice cream
But… will mayonnaise and strawberry ice cream taste like coffee? ‘Unfortunately, we have not included this aspect in our research. But I think it will because when I was conducting the experiments, it always smelled of coffee. The brown coffee colour is also visible in our flasks.’ Feng, who achieved excellent results with proteins and polysaccharides from soya during her PhD research, expects there are some technical and financial hurdles to be taken before the coffee substance can become a mainstream product in the food industry. She intends to follow the developments closely. ‘I am not a vegan, but I enjoy plant-based food. Whenever I see a new plant-based product in the supermarket, I am always eager to try it.’