Plant RuBisCo: An Underutilized Protein for Food Applications

Malnutrition is a public health concern and chronic protein malnutrition is prevalent in early childhood in many developing countries. Plant proteins are good candidates for meeting the growing protein needs. RuBisCo (ribulose-1,5-bisphosphate carboxylase/oxygenase) is a photosynthetic enzyme that exists in 4 forms (I, II, III, and IV), with form I being characteristic of higher plants. Form I RuBisCo represents 50% of leaf proteins, and is, therefore, important as a source of protein for nutrition and as a functional ingredient, although the laborious extraction process for plant proteins can limit their use in food products. Column chromatography is the most effective RuBisCo purification step for laboratory research, while ultrafiltration has shown prospects for large-scale applications. RuBisCo has excellent solubility in alkaline pH and at low denaturation temperatures. Thus, RuBisCo can form brittle gels at low concentrations, which can influence the chemosensory properties of products containing the proteins. Foaming of RuBisCo occurs around its isoelectric point, while emulsifying capacity proportionally increases with pH. Heating prior to emulsification increased the strength and stability of emulsion formed with RuBisCo. The protein is also attractive due to its high nutritional values and in vitro digestibility. Furthermore, RuBisCo is a competitive source of bioactive peptides with opioid-like, memory-enhancing, appetite-stimulating, antioxidative, and antihypertensive properties, demonstrating the wide range of food applications where RuBisCo can be utilized.