Exploring the functionality of coconut proteins
Abstract: Popular Abstract in English The potential of coconut proteins as food ingredients was studied with the aim of evaluating how plant proteins, in particular those from coconut, could find industrial applications and compete with proteins of animal origin based on meat, fish, milk or eggs. Three research directions were chosen for investigation, to evaluate how coconut proteins would perform in each of the following situations: Would coconut proteins be able to keep stable oil in water dispersions (emulsions), as in cows’ milk? Do coconut proteins stiffen when heated, like when an egg is boiled? Does full-fat coconut milk, heat-treated and homogenised, behave like mayonnaise, showing some initial resistance to flow under stress? These questions address important issues, as they can provide a general picture regarding the potential of coconut proteins for further investigation. There is a growing segment of vegetarians demanding nutritious protein products, comparable to those of animal origin. Products comparable to cows’ milk, yoghurt, butter, cheese, but based on plant ingredients, are desirable. However, the results were only satisfactory for the final two issues. In particular we were able to manufacture an additive free stable coconut milk despite the challenging properties of the coconut protein. This achievement was possible by using heat treatments and by concentrating the emulsion to obtain a loose gel like system. To understand the role of proteins in food systems, it is first necessary to determine the protein structure and intrinsic properties, such as amino acid composition, physical and thermal stability, and solubility. This then allows evaluation of the behaviour of protein in a particular food product. These properties are very important in food processing, as they determine characteristics such as texture, hardness, viscosity, and water and fat absorption. Plant oilseeds, including coconut, store reserve proteins for embryo growth during germination, and these proteins also have great potential for human consumption. They provide well-balanced nutrients, are cheap, widely available, and renewable. World oilseed production was 380 million tons in 2005 and protein meal 207 million, 69% derived from soya bean. Coconut protein has been overlooked for decades, unlike coconut oil, which is still the most important product in the sector. Despite the moderate protein content in the fresh coconut kernel (3-4%), the annual global output of 60 million tons of coconut provides a potential source of approximately 5000 tons of protein, which today is not utilized at all. The technology used in oil extraction is detrimental to the quality of coconut protein, because of negative effects arising from high processing temperatures, traces of solvents, and insect contamination during copra desiccation. This makes the protein unfit for human consumption. Our experiments were carried out using mild wet processing conditions, on fresh materials to meet food quality standards.
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