Evaluation of physicochemical properties and microbiological safety of pumpkin (Cucurbita pepo) seed composite flours

Abstract

The physicochemical properties and microbiological safety of pumpkin (Cucurbita pepo) seed composite flours were evaluated using standard analytical and microbiological assessment methods. The increased substitution of PSF into WF1 had significant (p<0.05) decrease on some functional properties of the blends such as water absorption capacity (WAC), oil absorption capacity (OAC), gelation capacity (GC) and bulk density (BD). WAC of blends ranged from 1.40±0.06 mL/g to 1.70±0.19 mL/g, OAC ranged from 3.22±0.19 mL/g to 3.55±0.15 mL/g, GC ranged from 15.50±0.79 % to 18.84±1.15%, and BD ranged from 0.41±0.07 g/mL to 0.69±0.10 g/mL. Conversely, as levels of substitution of PSF into WF1 increased, there was significant (p<0.05) increase on emulsifying capacity (EC), emulsion stability (ES), foaming capacity (FC) and foaming stability (FS). EC of blends ranged from 14.67±1.18% to 18.41±1.55%, ES ranged from 25.28±2.22% to 38.45±1.91%, FC ranged from 21.03±1.87% to 24.93±1.28%, and FS ranged from 41.49±1.78% to 48.81±2.03%. The blending of PSF into WF1 had significant (p<0.05) decrease on pasting attributes of the blends as protein content increased with the exception of pasting temperature. The values of pasting attributes ranges as: peak viscosity-PV (RVU) 1362.7±2.90 to 1445.5±3.10, trough viscosity-TV (RVU) 778.30±3.92 to 806.08±3.80, breakdown viscosity-BV (RVU) 628.10±3.33 to 658.22±2.15, final viscosity-FV (RVU) 1572.30±2.46 to 1693.9±3.64, setback value-SB (RVU) 843.4±2.04 to 901.8±1.98, peak time-PT (min) 5.88±0.28 to 5.64±0.29, and pasting temperature-PTemp ( o C) 89.28±1.77 to 91.74±2.11. Bacterial and fungal counts (CFU/g) of blended flours ranged from 2.83x10 3 ±0.09 to 3.15x10 3 ±0.52 and 3.59x10 2 ±1.81 to 3.92x10 2 ±1.12 respectively. The inclusion of different levels of pumpkin seed flour (PSF) into wheat flour (WF1) had good physicochemical and microbiological properties that would eventually result in safe, high quality and value added products.