Influence of Kersting’s (Kerstingiella geocarpa) groundnut proteins on the physicochemical, bioactive properties and storage stability of orange juice

Sweet orange ranks as one of the most acceptable fruit juices across the globe as it offers a healthy choice and pleasant taste to a wide spectrum of consumers. This makes it a promising vehicle for conveying functional ingredients into the human body. The present study was designed to produce functional orange juice by incorporating Kersting's groundnut proteins (isolate and hydrolysates) at different proportions (0.6, 0.8 and 1.0 w/v) into freshly produced sweet orange juice. The sample formulations were further analysed for changes in their physicochemical (pH, titratable acidity, total soluble sugars, ascorbic acid and total phenol content), sensory (appearance, colour, flavour, mouthfeel and overall acceptability), antioxidant (radical scavenging, metal chelating, ferric ion-reducing abilities, DPPH, total antioxidant) and antidiabetic (inhibition of α-amylase and α-glucosidase enzyme activities) properties as well as their storage stability over a 90-day storage period. The functional orange juice exhibited an improved physicochemical, antioxidant, antidiabetic and shelf life properties based on the respective protein concentrations used over the 90-day study period while the sample with the lowest proportion (0.6%) of functional ingredient had the highest sensory acceptability. Hence, the study concluded that Kersting's groundnut proteins could find useful applications in the formulation of functional orange juice.