Gelatinization and Viscosity Behavior of Single-Screw Extruded African Breadfruit (Treculia Africana) Mixtures

Abstract

Mixtures of African breadfruit (Treculia africana), corn and soybean were extruded in a single‐screw extruder. Feed composition (fc), feed moisture (fm) and screw speed (ss) were three process variables investigated at five level conditions. The fc was at 40:5:55, 55:5:40, 70:5:25, 85:5:10 and 100:0:0% (breadfruit, corn and soybean, respectively), fm was at 15, 18, 21, 24 and 27% while ss was at 100, 120, 140, 160 and 180 rpm level conditions using a second‐order response surface composite design. Process variable conditions that did not completely gelatinize the blends were further studied for proximate composition, energy demand and levels of gelatinization and viscosity. Crude protein significantly (P ≤ 0.05) increased from 17.52% in the control (100% breadfruit) to 34.14% in the mixture containing 40% of breadfruit. Carbohydrate reduced significantly (P ≤ 0.05) from 63.18% in the control to 40.41% in the mixture. Pellets were obtained at 15% fm while strands were produced at 21%, irrespective of other variables. The unextruded control showed an increasingly higher starch viscosity, ranging from 350 BU at peak to 365 BU on cooling to 52C than the mixtures. Soy addition increased gelatinization temperatures from 77.30 to 87.90C and from 68.80 to 78.90C in unextruded and extruded samples, respectively. Gelatinization and viscosity behavior of extrudates was most influenced at 100 rpm except where minimum fm was replicated. Specific mechanical energy for extrudate transformation ranged from 167 to 241 KJ/Kg in the mixtures while the changes in expansion ratio were not significant (P > 0.05).

Influence of Proecessing Methods on The Nutritional And AntiNutritional Composition Of Fluted Pumpkin And African Breadfruit Seeds.

“…The estimation is that by 2050 the world population will be nine (9) billion. That is three (3) billion higher than the current figure of six (6) billion. It has also been estimated that there will be an exponential growth more in the cities in developing countries, especially, in Africa and Asia [1] where food insecurity as well as child mortality due to malnutrition is endemic [2].…”

“…This forest tree legume is a member of the Mullberry family, Moraceae [6] and is known in Ibibio as 'Ubong Mbakara' and in Igbo as 'Ukwa'. The seed is widely consumed in the South-eastern Nigeria as snacks or pulverized and added to soups as thickener.…”

“…The seed is widely consumed in the South-eastern Nigeria as snacks or pulverized and added to soups as thickener. Findings by several authors have shown that the seed is a healthy source of nutrients and minerals [6,4,7]. It is regarded as one of the richest in benefits among plants consumed in the world [8] having been known to be primarily high in its content of aromatic amino acids [9], hence, a veritable source of good quality protein.…”

Residence Time Distribution (RTD) in a Single Screw Extrusion of African Breadfruit Mixtures

“…In general, extrusion cooking relies on conversion of shear and frictional energy to heat energy, which cooks (Grenus et al 1993) and improves digestibility by denaturing the protein, exposing new sites for enzyme attack and by inactivating inhibitors (Lorenz et al 1980;Rackis et al 1986;Iwe and Ngoddy 2000). The proximate composition, amino acid profile, and anti-nutritional composition of raw and extruded African breadfruit-corn-soybean mixtures had been reported in literature (Nwabueze 2006;Nwabueze 2007).…”

“…Its combination with soybean alone or soybean and corn to produce acceptable and improved protein quality products through fermentation and germination (Ariahu et al 1999) and extrusion cooking (Nwabueze 2006) had been reported. In addition, the potential for producing non-alcoholic beverage (Ejiofor et al 1988) and as raw material for bread making, cake, and cookies (Lawal and Bassir 1986;Giami et al 2004) had earlier been reported.…”