Nutritional, textural and sensory quality of biscuits supplemented with spinach (Spinacia oleracea L.)

Spinach (Spinacia oleracea L.) leaves were dried in a cabinet tray dryer at 55 °C and ground to pass through 220 µm mesh to obtain spinach powder (SP). Fresh spinach leaves yielded 6.5% of SP possessing 28.70% protein, 8.8% crude fibre. The powder was rich in essential minerals like calcium (1336 mg/100 g), iron (30 mg/100 g) and phosphorous (336 mg/100 g). Methanolic extracts (30-180 µL) of SP exhibited antioxidant activity as assayed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS) assay and ferric reducing power. Biscuits were prepared using 5%, 10%, and 15% SP and evaluated for their nutritional, textural, sensory quality and sorption behavior. Moisture sorption isotherm of SP indicated non-hygroscopic nature with an initial moisture content (IMC) of 8.6%, which equilibrated at 64% relative humidity (RH), whereas, biscuits were observed to be hygroscopic with an IMC of 0.94-1.26%, which equilibrated between 5-30% RH for control sample (CB), 5%, 10% and 15% RH for SP supplemented biscuits respectively. Textural quality revealed that hardness and breaking strengths increased with increased addition of SP. Sensory studies of biscuits showed that 5% supplementation of spinach powder was more acceptable.