Comparison of physical and chemical properties of wheat flour, fermented yam flour, and unfermented yam flour

Abstract

Yam is a root and tuber climbing plant and main calorie source in some tropical regions of Africa. In this study, properties of fermented (brown) yam flour (FYF) and unfermented (white) yam flour (UYF) were compared with refined wheat flour (RWF). The yam flours were lower in protein (3.3%–5.9%), arabinoxylans (0.93%–1.40%), phytic acid (0.17–0.53 mg/g), phenolic acids (0.57–2.28 mg FAE/g), amylose (17.3%–22.6%), and fat (0.2%–0.4%) but higher in potassium 119–845 mg/100 g), ash (1.70%–2.21%), total starch (73.8%–74.2%) and fiber contents (6.8%–7.0%). All the samples exhibited high (>90) estimated glycemic index (eGI) values. However, FYF and UFY had significantly (p < 0.05) lower eGI than RWF. Thermal studies showed that FYF and UYF required more energy for gelatinization than RWF. Compared to RWF, FYF swelled more rapidly and retrograded faster. FYF had significantly (p < 0.05) higher gel firmness than RWF and UYF. Overall, the flours exhibited different characteristics which will impact functional and nutritional properties. Practical applications Yam is a staple crop grown in tropical and subtropical Africa, the Caribbean, South Pacific, and Asia. Increased utilization of local staple crops in production of composite flours or in food products can increase economic gain for farmers and local economies. The study of the functional characteristics of the yam flours would allow for the development of tailor‐made composite flours for production of many unique food products. These yam flours may also be of use in formulation of gluten‐free products, especially products such as cakes and pastry that don't require high gluten strength.

Quality and Storage Characteristics of Hot Press Tortilla Prepared from Yam-Wheat Composite Flour

“…This result is in agreement with a previous report that found an increase in cellulose fiber caused an increase in water absorption of dough [32]. Also, the starch damage of the UYF flour is much higher than starch damage for wheat flours [26]. It is likely that the fermentation of the yams during the production of FYF resulted in an increase in starch damage.…”

“…The proximate composition and color of RWF and flour blends are shown in Table 1 and were significantly (P < 0.05) different among the different composite flours. The compositions of the UYF and FYF were found to be typical for unfermented and fermented yam flours [26]. The protein, ash, and starch con- yam flours that have lower protein contents.…”

“…A higher concentration of FYF flour. UYF did not have any PPO activity, while a small amount of PPO was detected in FYF [26]. The traditional definition of a good tortilla is one that has a uniform satiny white appearance with few browned spots.…”

“…The UYF had 18.1% starch damage, and 6.8% total dietary fiber, and the FYF had 3.0% starch damage and 7.0% total dietary fiber [26]. Typical values for starch damage and dietary fiber for refined wheat flour are around 7% and 4%, respectively [26]. The higher water absorptions value of UYF is attributed to its higher level of starch damage and fiber contribution.…”

“…The higher water absorptions value of UYF is attributed to its higher level of starch damage and fiber contribution. The UYF had 18.1% starch damage, and 6.8% total dietary fiber, and the FYF had 3.0% starch damage and 7.0% total dietary fiber [26]. Typical values for starch damage and dietary fiber for refined wheat flour are around 7% and 4%, respectively [26].…”