Effect of Processing on Bioaccessibility of Phenolics of Selected Legumes and their Antioxidant and Biological Activities

Sarusha Santhiravel
PhD Student
Department of Biochemistry


Date: November 17, 2023
Time: 1:00 p.m. to 2:00 p.m. 
Room: CSF 1302

Legumes are an essential part of a healthy and balanced diet containing essential macronutrients, dietary fibre, vitamins, and minerals. They also serve as excellent sources of a wide range of bioactive compounds, including phenolics. Epidemiological studies have shown that legume consumption lowers cholesterol and blood sugar levels and improves gut health. The effect of steam explosion pre-treatment on the composition of free, esterified, glycosylated and insoluble-bound phenolics of seeds of Eston lentils (Lens culinaris Medik) and its hulls as well as beach pea (Lathyrus maritimus (L.) Bigel) were investigated. Samples were subjected to steam explosion treatment followed by the extraction of phenolics using ultrasound-assisted method and alkaline and acid hydrolysis. The phenolic extracts were analyzed for their total phenolic (TPC), flavonoid and proanthocyanidin contents. Their in vitro antioxidant activity was determined by DPPH (2,2-diphenyl-1-picrylhydrazyl), and ORAC (oxygen radical absorbance capacity) assays. The phenolic extracts were then tested for their in vitro biological activities. After steam explosion treatment, total phenolic, flavonoid, and proanthocyanidin contents of the free phenolic fraction was increased significantly (p < 0.05), while those of the esterified, glycosylated, and insoluble-bound phenolic fractions decreased. The same trend was observed for their antioxidant activity in the assays performed. Moreover, phenolic extracts showed effective inhibitory effects against LDL-cholesterol peroxidation, activity of α-glucosidase, α-amylase, and pancreatic lipase and formation of advanced glycation end products (AGEs). Steam explosion pre-treatment had a significant effect in these in vitro bioactivities. Among all sample tested, free phenolic fraction of Eston lentil hulls demonstrated substantial increase of TPC and antioxidant activity upon steam explosion. Overall, steam explosion is an efficient method to release phenolics from the insoluble-bound fraction of selected legumes and enhancing their potential in the production of value-added products.