Extrusion Processing of Raw Food Materials and by-products:A Review

Extrusion technology has rapidly transformed the food industry with its numerous advantages over other processing methods. It offers a platform for processing different products from various food groups by modifying minor or major ingredients and processing conditions. Although cereals occupy a large portion of the extruded foods market, several other types of raw materials have been used. Extrusion processing of various food groups, including cereals and pseudo cereals, roots and tubers, pulses and oilseeds, fruits and vegetables, and animal products, as well as structural and nutritional changes in these food matrices are reviewed. Value addition by extrusion to food processing wastes and by-products from fruits and vegetables, dairy, meat and seafood, cereals and residues from starch, syrup and alcohol production, and oilseed processing are also discussed. Extrusion presents an economical technology for incorporating food processing residues and by-products back into the food stream. In contemporary scenarios, rising demand for extruded products with functional ingredients, attributed to evolving lifestyles and preferences, have led to innovations in the form, texture, color and content of extruded products. Information presented in this review would be of importance to processors and researchers as they seek to enhance nutritional quality and delivery of extruded products

Fabrication and characterisation of metal-doped pectin films

Metal-doped pectin films have been fabricated and their thermal, mechanical and microstructural properties were examined by means of complementary physicochemical techniques. Films were fabricated at two pH values, 2.0 and 7.0, with inclusions of metals (Na , K , Ca , Mg and Al ) and conditioned in a range of relative humidity environments. Glass transition temperatures (T ) of water-plasticised films ranged between 54 and 95 °C. Treatment of T values with Gordon-Taylor empirical model revealed a spectacular increase (∼25 °C) of the T of dry films at pH 2.0 and with the addition of metals. Uniaxial extension measurements revealed that, at pH 2.0, films were stronger with lower extensibility in contrast to their counterparts prepared at pH 7.0. All films were microstructurally inspected and revealed a continuous one-phase microstructure at length scales >100 μm with no significant differences in the surface topography. Changes of the physical properties of films have been attributed to the modulation of the intermolecular interactions that are influenced by the degree of ionisation of carboxyl groups (pH), electrostatic interactions (inclusion of cations), and conformational reorientation of pectin chains. Overall, it has been shown that it is possible to engineer biopolymer films for a range of applications depending on the desired operating environment

Vibration analysis of journal bearings under water contaminated lubrication

Water as a common contaminant in the lubricating oil can degrade lubricant performance and cause a serious fault of the journal bearing and shorten its service life. Differing from the pure lubricating oil, the contaminated oil with water exhibits a non-Newtonian behavior and has a significant impact on the dynamic performance of the journal bearing. This paper is to establish a relationship between the water contamination and the vibration response of the journal bearing in order to achieve an online condition monitoring of the tribological behaviour of journal bearings. The research progress regarding to the effects of water contamination on the lubrication is firstly reviewed. A theoretical model is then developed for the dependence of the viscosity of the contaminated oil on the shear rate and temperature. The effects of such rheological behavior on the dynamic performance of the journal bearing are also studied. To validate the theoretical analysis, the rheological measurement for the contaminated oil with such water fraction as 0, 1, 3, 5, 7 and 10 per percent by volume, is carried out with the Malvern Bohlin Gemini HR rheometer. Those contaminated oil are then fed into the bearing housing. Through accelerometers attached on the housing, vibration responses of the journal bearing are acquired under different working condition. The results outlined that volume water ratios in lubricating oil had the different degrees of effects on the tribological behaviour of journal bearings, which allows early detection of abnormal lubricants to be implemented online vibration responses

Structure and physicochemical properties of Ghanaian grewia gum

Grewia polysaccharides were isolated using sodium metabisulphite and phosphate buffers and the influence of the different extraction techniques on the chemical composition and structural characteristics of the extracts were determined. Structure and chemical composition of the resulting polysaccharide extracts were determined using FT-IR and NMR spectroscopy, neutral sugar analysis, size exclusion chromatography coupled to multi-angle light scattering (SEC-MALS), dilute solution viscometry and steady shear rheology. Chemical composition was similar irrespectively of the extraction solvent used and ranged between 11.1 and 16.5% for protein, 53.4 and 66.9% for total carbohydrate, 18.5 and 35.1% for total uronic acid and 23.5 and 28.6% for rhamnose. Predominate sugars in the extracts were rhamnose and uronic acids with spectroscopy showing the presence of esterified groups. Intrinsic viscosity varied between 6.5 and 9.1 dL g and related with molar mass (754–2778 × 10 g mol ). Grewia polysaccharide dispersions at 1 g dL exhibited a shear thinning flow behaviour with crude and sodium metabisulphite extracts having higher viscosities. Overall, differences in extraction techniques produced grewia samples with tailored bulk properties for use in the food and pharmaceutical industries