No abstract

Thermal degradation of sugars and amino acids, and depolymerization of macromolecules such as starch, proteins and fibre occasioned by high-temperature short-time extrusion cooking modify the physicochemical and functional properties of raw materials. High-temperature short-time extrusion cooking holds promise for the expanded use of non-conventional ingredients as food/feed due to its practicality, increased productivity and efficiency, and ability to retain thermally degradable nutrients during cooking. However, little is known about the effect of the high-temperature short-time extrusion cooking process on the physicochemical properties and starch digestibility of lesser-known grain legumes such as African yam beans (Sphenostylis stenocarpa), Pigeon pea (Cajanus cajan), and Bambara peanut (Vigna subterranean). In this study, we investigate the effect of high-temperature short-time extrusion cooking and extrusion cooking temperature; low (100°C) vs high (140°C) temperatures in a single screw extruder, on hydration characteristics, viscoamylolytic properties, in vitro starch digestibility and digestion kinetics of these grain legumes. We show that water holding capacity and swelling power increased (p < 0.05) with increasing extrusion temperature for Sphenostylis stenocarpa and Vigna subterranean but not Cajanus cajan extrudates. Significant effects of extrusion cooking (i.e unextruded vs 100°C and unextruded vs 140°C) and extrusion temperatures (i.e. 100°C vs 140°C) were observed in peak, trough, final and setback viscosities of all extrudates. Starch digestibility and digestion characteristics were modified with increase in extrusion temperature, however, no effect of extrusion temperatures (i.e. 100°C vs 140°C) on starch digestion kinetics was observed for Sphenostylis stenocarpa and Vigna subterranean except for hydrolysis index (34.77 vs 40.77%). Nutritional and physiological implications of extruded grain legumes in monogastric animal feeding were also highlighted. The Information presented herein will influence expanded use of extruded grain legumes as feed ingredients for intensive monogastric animal feeding.

Starches from different botanical origin (sago, rice, wheat, corn, sweet potato, arrowroot, and potato as well as sweet potato meal, cassava pulp, and tapioca) with varying total starch (TS) and amylose content were assessed for hydrolysis in vitro by gastric enzymes and their starch fractions were characterized as rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). The relationship between starch hydrolysis (SH) and organic matter digestibility, as well as total variability among TS, amylose content, RDS, SDS, and RS fractions of these test starches were also studied. SH varied significantly ranging from 9.8% in potato starch to 85.5% in sago starch with organic matter digestibility (OMD) of 22.36 and 95.04%, respectively. Significantly positive relationships were also recorded between SH and OMD, SDS, RDS and a significantly negative relationship with RS. Prediction equations were proposed to estimate SH from OMD and TS, and the correlation between estimates and determined SH values was high (r = 0.89, p < 0.0001), alluding to the possibility of estimating SH in starches using OMD and starch content values, hence enabling fast screening and predictability of starch fermentation kinetics for various aspects of nutrition studies.

Reducing the cost of production while maintaining or increasing the productivity has been a major challenge of pig industry in Nigeria. This gives rise to the use of processing techniques that improve the utilization of relatively cheap feed ingredients. Extrusion cooking process has the potential of improving the digestibility and absorption of rice bran by solubilizing high fibre, deactivating anti-nutritional factors and stabilizing lipolytic enzyme activities in rice bran. This study was conducted to evaluate the effects of extruded rice bran based diets on the performance, intestinal microbiota and morphology of weaned pigs. Forty-eight female Large White × Landrace weaned pigs were randomly allotted to three treatments consisting of a control (T1) with 30% inclusion level of raw rice bran; T2 with 30% inclusion level of extruded rice bran extruded at 100 °C, T3 with 30% inclusion level of extruded rice bran extruded at 120 °C. The final body weight, weight gain, and feed conversion ratio were significantly (P < 0.05) higher in pigs on T3 compared with the control group. Morphology data for the small intestine showed that T3 had higher villi (604.15 μm 10−6) and crypt depth (153.86 μm 10−6) in comparison with the other treatments. Extrusion cooking processing techniques had a positive impact on body weight gain and feed conversion ratio of the experimental animals as well as improved their intestinal microbiota and morphology.

No abstract