TITLE:
Influence of Feed Rate, Moisture and Mixture Composition from Composites Containing Rice (Oryza sativa), Sorghum [Sorghum bicolor (L.) Moench] and Bamboo (Yushania alpine) Shoots on Physical Properties of Extruded Flour and Mass Transfer
AUTHORS:
Wafula Nobert Wanjala, Omwamba Mary, M. Mahungu Symon
KEYWORDS:
Bamboo Shoots, Extrusion, Physical Properties, Mass Transfer
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.11 No.8,
August
24,
2020
ABSTRACT: Raw material composition, loading rate and moisture
level in extrusion processing have a direct bearing on physical properties of
the product besides other extruder operational parameters. These properties
greatly influence the consumer appeal, package design and shelflife of the product.
This study aimed at evaluating the effect of sorghum and rice flour containing
bamboo shoot flour (BSF) and other ingredients on resultant flour and
product throughput. A commercial single screw extruder with a constant barrel
temperature of 250°C and screw speed of 1480
rpm was used. Five different blends (100:0:0, 70:30:0, 60:30:10, 55:30:15 and
50:27:23 for rice, sorghum and BSF respectively, on dry weight basis) were
extruded at three levels of water addition (15, 20 and 25 kg/h) and two feed
rates (1800 and 2100 kg/h). Extrudates were analyzed for expansion ratio (ER).
Extrudates were then milled to particle size of 2 mm and flour samples were
analyzed for hydration properties, colour, bulk density (BD) and oil holding
capacity (OHC). Product throughput was calculated using mass balance equation
based on dry matter content of the raw materials and the corresponding extruded
product. Mixture composition significantly affected all physico-chemical
properties analyzed for the products except water solubility index (WSI). Feed
rate significantly affected all physico-chemical of the product properties
except WSI and colour lightness (L*).
Water addition significantly affected product mass transfer, ER, BD, colour and
swelling capacity (SC). Therefore, BSF can be blended with other ingredients
and extrusion parameters be manipulated to give forth a product with desirable
properties.