RÉSUMÉ
This study explored the potential of African walnut in the formulation of composite flour which can be used for bread production and in various food applications. African walnut flour was produced and used to substitute wheat flour at different levels (5 - 25%) in the production of wheat-African walnut composite flour. Functional and pasting properties of the composite flour were evaluated using standard procedures. Proximate composition, antioxidant activity, some loaf quality attributes and sensory acceptability of bread produced from the composite flour were evaluated using standard procedures. Wheat bread served as control. The composite flour showed varying functional properties which ranged from 2.43 to 3.46 (swelling capacity), 1.15 to 1.85 mL/g (water absorption capacity), 2.15 to 2.75 mL/g (oil absorption capacity), 10.80 to16.60% (foam capacity), 63.0 to 75.0% (dispersibility), 38.92 to 69.92 seconds (wetability), 0.75 to 0.79 g/mL (packed bulk density) and 0.43 to 0.47 g/mL (loose bulk density). Inclusion of African walnut reduced peak viscosity (53.92 – 148.83 RVU), trough viscosity (52.25 – 88.58 RVU), breakdown viscosity (1.67 – 60.25 RVU), final viscosity (74.08 – 191.25 RVU) and setback viscosity (21.83 – 102.67 RVU) of the composite flour. Composite bread had better protein (9.75 – 16.93%), fat (3.42 – 9.94%), ash (1.46 – 2.75%), crude fibre (0.86 – 3.64%) but reduced specific loaf volume (2.36 – 4.18 cm3/g) and loaf height (3.00 – 5.40cm) than the control, and exhibited appreciable antioxidant activity (DPPH: 31.60 – 73.09% and FRAP: 0.51 - 4.25 mg/g). In term of sensory acceptability composite bread samples produced with 5 and 10 % levels of African walnut compared favourably with bread produced from wheat flour. Thus composite flour produced from wheat and African walnut flours showed an array of physicochemical properties which could make it useful in different food applications. Acceptable bread could be produced from wheat flour substituted with African walnut flour at 10% level.
RÉSUMÉ
This study was carried out between July-September, 2017 at Food and Industrial Microbiology Laboratory, University of Port Harcourt, Port Harcourt Nigeria. 1 %, 3 % and 5 % citric acid were separately added to brine solution containing pickled African walnut inside three glass jars, and sterilised. Similarly, 1 %, 3 % and 5 % lactic acid was added to already sterilised pickled African walnut mixed with brine solution. Pickled African walnut without preservative was the control sample. The entire setup was stored for 6 Wks at room temperature (28±2°C). At 1 Wk interval, pH of the samples was monitored. Proximate composition and antinutrients in freshly cooked African walnut (FCAW) and pickle from each glass jar were determined using standard methods after 6 Wks storage period and sensory characteristics by 9 point Hedonic scale. The antinutrients, fibre, ash and carbohydrate content of FCAW were higher than that of pickled samples after 6 weeks storage period. The protein content of the pickles ranged between 24.12-25.20 %, ash 2.88-3.22 %, moisture 31.55-33.33 %, fat 28.30-29.24 %, fibre 0.90-1.21 % and carbohydrate 10.08-10.49 %. All the parameters evaluated showed significant differences (P = .05) among the samples. Very strong correlation exist between the proximate composition of the pickles preserved with same concentration of citric and lactic acid but level of antinutrients and sensory evaluation scores of the pickles exhibited weaker correlations with few exceptions. During storage, pH of FCAW steadily increased from 5.6-7.0 but that of pickled samples which ranged between1.8-4.0 decreased. The pickles met U.S. Code of Federal Regulations (21 CFR Part 114) which stipulate that acetic acid added to food products must maintain its pH at 4.6 or below. Sensory evaluation revealed that pickled African walnut preserved with 5 % lactic acid was most preferred. Pickled African walnut preserved with citric and lactic acid is well acceptable to consumers. The preservatives slightly affected its nutritional composition, reduced its pH and level of antinutrients.