Writing in the journal Food Chemistry, the researchers report results from the analysis of defatted carob germ flour and the protein isolate, and suggest the proteins could have significant potential for health foods.
"These results could be useful in the study of different functional properties of carob germ proteins, and the application of these proteins as nutritional ingredients in formulated food," wrote the authors from Universidad de Sevilla, Instituto de la Grasa (CSIC), and CIDCA (CONICET).
The alternative protein market is growing at a rapid pace, for a variety of reasons. Alternative sources of protein are having a profound influence on the formulation of weight conscious food and diets based on low glycaemic index (GI) and high protein intake, and traditional manufacturers are beginning to take a look at new protein sources as a means of enriching their products.
Carob powder is already used by the food industry as a chocolate substitute, since it is a natural sweetener with flavour and appearance similar to chocolate. It is also caffeine- and theobromine-free.
Lead researcher Dr. María Cecilia Puppo told FoodNavigator.com: "Carob flour is a food ingredient applied to the elaboration of bread, cakes, cookies, snacks, cereal bars and bakery products in general, nevertheless it use is not widely promoted in bakery industry.
"In Spain some industries processes carob for obtaining carob germ flours (46 per cent protein) enriched in lysine and arginine amino acids. This flour is used in dietetic formulas for sports and celiac people."
Poppo and co-workers sought to characterise the protein isolates in order to explore their potential for the alternative protein market.
Using an alkaline extraction technique followed by isoelectric precipitation of proteins, the researcher obtained a protein isolate with a protein content of 96.5 per cent.
"A protein isolate may be an attractive ingredient to use in the production of human food, as it has reduced levels of undesirable components, like fiber, lipids or darkening agents," wrote the authors. "The results for the protein isolate are in concordance with the criteria of the minimum protein content used in obtaining a protein isolate (higher than 85 per cent)."
The major amino acids present were characterised as glutamic acid, aspartic acid and arginine, while the overall proteins were composed of aggregates of 131 and 70 kDa subunits.
"The knowledge of the nature of proteins that form carob materials like germ flours and isolates, and its thermal properties would be important from the point of view of the application of this crop as ingredient in formulated foods," the added.
In an email correspondence to this website, Dr. Puppo said that additional studies need to be performed in order to define the different functional properties of carob protein isolates such as emulsification, foaming, and gelation, to confirm the potential technological use of these proteins in the food industry.
"Nevertheless, in several conditions of pH and protein concentration, carob proteins are able to form stable emulsions, like mayonnaise, with different rheological properties," she said.
And commenting on the potential cost of carob protein isolates, Dr. Puppa noted that, compared to pea and soybean proteins, in her opinion, the cost of carob flour would be high. This would be due to the expense of obtaining carob tress that can reach the optimum stage for producing carob pods.
"The cost depends on this initial inversion; on the costs of input materials and the benefits obtained in the commercialization of carob flour," she said.
Dr. Puppa confirmed that work was continuing in the area, with the next stage to study different functional properties of carob germ flour.
The market for alternative proteins is becoming a little bit more competitive, though it remains very much a niche sector. Over 90 per cent of protein is still sourced from soy and milk-derived caseinates, though a speciality pea protein sector is on the rise.
Carob is exploited predominantly for the industrial transformation of the seeds, to obtain locust bean gum (LBG), used as thickening agent in food preparations because of its ability to form viscous solutions and to stabilize emulsions and dispersions.
Source: Food Chemistry (Elsevier)
Volume 107, Pages 675-683
"Composition and structure of carob (Ceratonia siliqua L.) germ proteins"
Authors: C. Bengoechea, A. Romero, A. Villanueva, G. Moreno, M. Alaiz, F. Millan, A. Guerrero, M.C. Puppo