Functional Properties of Protein Concentrates of Cowpea and Bambara Bean Involving Different Drying Techniques

Abstract

The effect of different drying methods used in the preparation of protein concentrates from different cultivars of cowpea and bambara bean was investigated. Protein was extracted by the isoelectric precipitation method and subsequently dried by cabinet drying (CD), vacuum drying (VD) and freeze drying (FD). The protein extraction yield and protein content were high. The subunit composition of protein concentrates was characterized by electrophoresis. The drying methods affected water-holding capacity, oil absorption capacity and solubility of protein concentrates depending on cultivars. Water-holding capacity was adequate for its utilization in viscous foods. The protein concentrates prepared by FD showed higher oil absorption capacity than those by CD and VD. The protein concentrates prepared by FD showed lower solubility at pH 2-6, and above pH 6 the concentrates prepared by VD presented higher solubility compared with those by CD and FD. This study provided useful information to optimize utilization of legume protein concentrates in the food industry. PRACTICAL APPLICATIONSCowpea and bambara bean cultivars could be used in the preparation of protein concentrates due to their good nutritional quality and low cost. Techniques used during the preparation of protein concentrates usually involve the conversion into a dry powder form that facilitates stable and long-term storage, enabling their use as ingredient in food applications. In this regard, the effect of cabinet drying, vacuum drying and freeze drying in the functional properties of cowpea and bambara bean protein concentrates was investigated. The freeze-drying technique was adequate for utilization of concentrates in viscous foods, bakery products and in the cold meat industry as these concentrates presented high water-holding and oil absorption capacities. The vacuum-drying technique produced concentrates with high solubility at pH 2 and above pH 6, and was adequate for concentrates that could find utilization in the fortification of beverages. Choosing appropriate drying technique and cultivar could determine utilization of protein concentrates in the food industry.

Amino acid profile, pasting, and sensory properties of croissant snacks produced from wheat‐fermented Bambara flour

“…The onset of gelatinization occurred faster for flours with a high inclusion level of fermented Bambara, and retrogradation decreased as levels of Bambara groundnut flour increased. The behavior in pasting characteristics among starches could be due to differences in amylose content, crystallinity, and the presence or absence of amylose–lipid interaction (Mune Mune & Sogi, 2015). The results obtained in this study are similar to the findings of other authors.…”

Response surface methodology for investigating structure–function relationship of grain legume proteins

“…The variables with confidence levels above 95% were considered significant. As the concentrates presented different protein content, and on the basis that protein content was important for functional properties (Mune Mune & Sogi, ; Zayas, ), before coding each secondary structure proportion and surface hydrophobicity were expressed in terms of protein content (specific property × protein content/100).…”

“…The drying methods affected functional properties as well as structural and physicochemical characteristics of proteins including solubility, surface hydrophobicity, surface tension, and secondary structure. Moreover, it is also well‐known that the drying processes used in the food industry could not break down legume proteins into smaller polypeptides (Joshi, Adhikari, Aldred, Panozzo, & Kasapis, ; Mune & Sogi, ; Zhao et al, ). As functionality is influenced by the physicochemical properties and conformation of proteins, it is interesting to predict the direction and magnitude of any induced change on the functional properties, and relate functionality to physicochemical properties such as solubility, hydrophobicity, and protein conformation.…”

Influence of pH and temperature on the physicochemical and functional properties of Bambara bean protein isolate

“…Bambara groundnut is drought tolerant with good yield performance in unfertilized soils, exhibiting remarkable resistance to pests and diseases ( Thammarat et al., 2015 ). Besides this, it is a potential replacement of animal protein in local households, often formulated in sauces and consumed with roots, tubers and cereals ( Mune Mune and Sogi, 2015 ). Despite its ability to withstand harsh climate and contribute to household protein requirement, Bambara groundnut is under little exploitation at both the indigenous and development research communities ( Yao et al., 2015 ).…”

“…However, limited scientific evidence elucidates the major factors coordinating the successful exploitation of Bambara groundnut flour in the food industry. Bambara protein is rich in essentially amino acids with substantial levels of lysine and methionine that greatly influence structure and function primordial in food formulation ( Mune Mune and Sogi, 2015 ; Mune et al., 2018 ). The application of protein rich sources in food engineering make use of processing parameters sometimes involving pH and temperature adjustments for stability.…”