Yam Properties Research Articles

Physicochemical properties of yam starches from fifty-five lines of Dioscorea species

This study investigated the morphology of the granules, physicochemical and pasting properties of fifty-five starches of Dioscorea rotundata and Dioscorea alata varieties. The granules sizes and shapes, swelling power, solubility, water absorption capacity, water binding capacity, pH, titratable acidity and pasting properties were evaluated by standard procedures. The result of the granule morphology showed that both varieties were in the range of large starch granules, however, D. rotundata varieties (32.40 – 57.01 µm by 22.38 – 35.70 µm) were significantly larger than those of D. alata varieties (18.33 - 48.91 µm by 13.38 – 33.10 µm). The granule sizes were observed to have a significant effect on the physicochemical properties, as D. rotundata species were significantly higher in swelling power (7.50 g/g) and lower in water absorption (66.20%) and water-binding capacities (57.16%). Also, D. rotundata species showed significantly higher peak viscosity (518.50 RVU), holding strength (260.95 RVU) and breakdown viscosity (257.54 RVU), all contributing to their potential industrial uses. The present characterisation of fifty-five varieties of Dioscorea species germplasm in Nigeria adds to the database on physicochemical properties of yams, providing relevant information for both food and non -food uses.

Effect of Soaking Prior to Oven-Drying on Some Nutrient and Anti-Nutrient Properties of Bitter Yam (Dioscorea dumetorum)

Soaking may improve the bitter yam properties processed by traditional method of drying and milling. The study investigated the effect of soaking prior to the traditional method of drying and milling on some nutrient and anti-nutrient properties of bitter yam flour. Four equal parts of cleaned, peeled and sliced bitter yam tubers were respectively soaked in clean water for 6, 12, 18 and 24 hours, dewatered, oven-dried at 50°C and milled, using standard procedures. The peak effect was recorded in the sample soaked for 24 hours which increased respectively by 13.12%, 29.41% and 0.81% for moisture, fat and carbohydrate, but decreased by 19.61%, 11.44%, 10.85%, 48.00% and 47.17% for crude fibre, ash, protein, alkaloid and tannin relative to control. Soaking, irrespective of time, prior to oven-drying (50°C) significantly improved the moisture and fat contents, but diminished the studied antinutrient and the other nutrient content of the bitter yam flour. The processing method did not favor the preservation of most of the studied properties. We recommend soaking prior to oven drying when the desired effect is overriding. Further studies, including sensory evaluation are warranted to address the possibility that the method may yield less bitter flour.

Beneficial effects of yam on carbon tetrachloride-induced hepatic fibrosis in rats

In a previous study, lyophilised yam reduced brain amyloid beta-protein (Abeta) accumulation and improved the antioxidative defence system in senescence-accelerated (SAMP8) mice. Therefore, the aim of this study was to investigate the hepatic protection of yam in the carbon tetrachloride-induced hepatic fibrosis of rats. Hepatic fibrosis was induced in rats via intraperitoneal injections of CCl(4) at a dose of 1 mL kg(-1) body weight (BW) twice weekly for 8 weeks. Three groups of rats were gavaged daily with yams at doses of 0.5, 1 and 2 g kg(-1) BW for 8 weeks, respectively. Yam treatments significantly decreased the ratio of liver/body weight, levels of gamma-glutaminotranspeptidase (GGT), low-density lipoprotein, and triglyceride in serum when compared with those administered CCl(4) alone. Treatment with yams significantly elevated antioxidant activities of glutathione peroxidase (GSH-Px) and superoxidase dismutase (SOD) in livers. Microscopically, yam-treated groups presented with low histoscores of CCl(4)-induced liver injury and fibrosis. Additionally, yam treatment reduced the area of GGT-positive foci and the index of proliferating cell nuclear antigen (PCNA) in liver. Daily administration of yam attenuates CCl(4)-induced hepatic fibrosis in rats in a dose-dependent manner; this attenuation may be related to the antioxidant properties of yams.

Determination of relevant sensory properties of pounded yams ( Dioscorea spp.) using a locally based descriptive analysis methodology

A panel of adult village dwellers was trained in descriptive analysis method using a local language of whom panellists are familiar to describe the properties of a popular pounded yam ( Dioscorea spp.), called “foutou”. The different samples of “foutou” were made from four major varieties of two species of yam ( Dioscorea cayenensis-rotundata and Dioscorea alata) and an industrially prepared yam product called Bonfoutou ®. In all, 21 attributes were identified, 9 of which were used for profiling. Lumpiness and springiness of the mass varied markedly with species. Greyish colour, fibre content, “easiness to mould” and sweetness differed among the varieties. Preferences were tested by a group of traditional yam consumers. “foutou” made from D. cayenensis-rotundata was preferred due to textural attributes. “foutou” made from D. alata was disliked. “Easiness to mould” and springiness appeared relevant to general preference for pounded yam and lumpiness contributed to explain “foutou” aversion. The study showed a list of determining attributes that could be used to describe pounded yam. It showed also that descriptive test was a suitable method of sensory analysis, which could be used outside the laboratory, under real conditions conforming to traditional patterns of eating and of a West-African food.

Computation of Bending Behavior of Woven Structures Using Optimization Techniques

This paper describes a mechanical model to predict the behavior of plain-woven fabrics under pure bending. A generalized energy approach that handles the nonlinear properties of constituent yams is used in the formulation. The model takes into account fabric set as well as yam compression previously ignored in many analyses. The model is validated against the experimental data of both monofilament fabrics and glass fabrics, and there is reasonably good agreement. The model gives rise to a computationally efficient algorithm that can be solved using readily available mathematical software based on nonlinear programing optimization techniques.

Combination Effects of Open-End Rotor Spun Hybrid Yarns

We have developed a mechanical hybrid yarn spinning system that produces different yam types on a modified open-end rotor spinning frame. In order to improve yam properties and produce novel yams, we investigate the effects of combinations with typical hybrid yams by inserting two filament yarns with varying filament over-feeds. The results are a new rotor spun loop (RSL) yam made by combining two aspects of typical hybrid yarn production into one process, and an RSL yam where a filament yam, fed with a core filament over-feed (CFOF), is located in the center of one yarn and the other filament yam, fed with the effect filament over-feed (EFOF), makes a loop on the yarn surface. The stable conditions of RSL yam production are within a range of EFOF ≧ 4 (m/min) and -6.0 << CFOF << -4.0 (m/min).

Producing Medium Count Yarns from Recycled Fibers with Friction Spinning

Yams production from recycled fibers (RF) is limited, and spinners often prefer to produce coarse yams from these fibers. In this research, we attempt to produce middle- count twp-component and three-component yams from RF in such a way that the RF in the yarn core are completely covered by virgin cotton fibers. To improve the tensile properties of such yams, we produce a three-component yarn with a continuous filament in its core, RF in the middle layer, and virgin cotton fibers in the sheath, using a friction spinning machine modified for this purpose. The results show that the appearance of the 51/49 cotton/RF two-component yams is like that of a 100% cotton yarn, and the imperfections of the RF sliver have no significant effect on yarn appearance. The results also show that the strength of a two-component yarn is greater than that of a 100% RF yarn. Spinning a 30 tex yarn from 100% RF is very difficult, and the end breaks are extremely high. In practice, it is impossible to produce yarn from RF. However, producing a 30-tex two- component yarn using RF with new fibers in the sheath is easy and trouble-free, but the yarn is weak. The tensile properties of the yarn show that the strength and elongation of a 30-tex three-component core yarn are greater than those of an equivalent 100% cotton yarn, a cotton/RF yarn, and a 100% RF yarn. Also, the irregularity of the three-component core yarn is less than those of cotton/RF and RF yams. Thus, we show that medium count yams of acceptable appearance and tensile properties can be produced from RF.

Compression of Plain Knitted Fabrics Predicted from Yam Properties and Fabric Geometry

This work proposes a simple theoretical model for plain knitted fabric compression. The work assumes that plain knit compression can be obtained from a combination of piled layer (PL) yarn compression and single layer (SL) yarn compression with a contribution factor depending on the fabric geometry. Experiments involve compression of plain knitted fabrics made from 2/19 and 2/29 tex cotton and 2/43 tex cashmere yams and their compression properties. The relation between compressional energy and cover factor is also investigated. A comparison of the experimental pressure-displacement curves of the fabrics and those calcu lated based on the theoretical model using the experimental compression data of the yarns shows that the model is acceptable for explaining plain knit compression. This model can be considered as a basic step toward improving the knowledge of knitted fabric compression as it relates to yarn compression and fabric geometry.

Reducing Yarn Hairiness with a Modified Yam Path in Worsted Ring Spinning

The spinning geometry of a ring frame plays an important role, and the twist triangle is the critical region in ring spinning. Changes in the spinning geometry may affect yarn properties. This paper examines the idea of ring spinning with a "diagonal" yarn path, and the effect of such a path on yam properties, particularly hairiness. Both "left diagonal" and "right diagonal" yam arrangements are tried on a 24-spindle Cognetex FLC worsted ring frame. The hairiness results obtained from the Zweigle hairiness meter show that the right diagonal yam path produces yams of lower hairiness than the conventional ring spun yarn in almost all the hair length groups. Yam evenness and tenacity are not as sensitive to the change in yarn path. The mean spindle speed at break is also tested, and there is some deterioration in spinning efficiency with the right diagonal yarn path, particularly at higher spinning speeds. Results from this study may help explain variations in yarns spun on poorly aligned ring frames.

Evaluating and Comparing the Physical Properties of Spliced Yarns by Regression and Neural Network Techniques

Different spliced yam properties (strength, bending, abrasion, and appearance) are merged into a single score, also known as the total score, which is then used to analyze the overall performance of the yarns. A regression model and neural network model are set up according to the total score to predict the performance of the spliced yams, and the two analysis techniques are compared. According to the analytical results. the neural network model gives a more accurate prediction than the regression model.

Cotton Wax and Its Relationship with Fiber and Yarn Properties

In this study, thirty-six cultivars of U.S. upland cotton are selected and their wax content determined by the Conrad method. Both ring spun and open-end yarns are then made from these cottons. Various fiber and yarn properties are measured before and after wax removal using AFIS, HVI, the West Point cohesion tester, and the Uster Tensorapid yam tensile tester, Correlations of wax content with fiber properties and yam properties are analyzed.

Developing a Twist Draft Spinning System for Small-Scale Production of Special Material Yarns

This paper presents a new spinning system, a kind of twist draft spinning in which the withdrawal tension in a yam being spun out is used to control its count. This system produces the yam directly from a large mass of fibers in a pot, can spin even low quality fibers that are difficult to spin with modem spinning systems, and is able to keep up with small-scale production of functional yams made from special materials. The spinning process is analyzed and the relation between the yam properties and the fiber properties is revealed. This relation is a valuable tool for designing properties of yarns spun with twist draft spinning. Several functional yarns of a special material are also spun with this system.

Validity of Adjusting Density of Material Fiber Mass in Twist Draft Spinning Frame

In order to add higher value to spun yarns, we have studied the application of a twist draft spinning to multi -kind small-lot production of functional yams. In twist draft spinning, a yarn is spun out directly from a large mass of material fiber and the yam count is controlled by spun yam tension. In this paper, we specially have regard to the linear de n-sity and twist rate of the yarn those are deeply concerned with quality of the yam. Through an analysis of the yam properties, it is found that the density of material fiber mass is the most effective parameter in properties of material fiber to adjust twist factor of the yarn. Furthermore, the linear density and the twist factor of the yam can be controlled independently by using spun yam tension and density of material fiber mass as adjusting parameters.

Physical Properties of Pneumatically Spliced Cotton Ring Spun Yarns

The overall properties of yams spliced under different splicing conditions are investi gated, including strength, bending, abrasion, and appearance. A statistical model that helps to predict the overall properties of the splices under different splicing and yam parameters is established, and the optimum splicing conditions (optimizing both the splicer and the yam parameters) are investigated. The results also indicate that yam linear density is the parameter that has the most important effect on the overall properties of spliced yams.

Hollow Yarn in Friction Spinning

"Hollow" yams have been created to improve cotton yam properties, to increase the entrapped air in the yam, and to gain a stronger yam for spinning and weaving processes. Hollow yams are spun by introducing PVA filaments into the yam-forming zone of an experimental friction spinning apparatus. A 61/18-denier (6.8 tex) PVA multifilament is used as the core and cotton fibers form the sheath. The water soluble PVA in the center is removed from the yam structure in boiling water with a good extraction of more than 95%. The effect of the PVA proportion on the mechanical properties of the hollow yam is examined, and its properties are compared with those of conventional cotton yams. The results show that the strength of the yam before boiling significantly increases as the PVA percentage increases, and it is more than that of an equivalent conventional cotton yarn. The strength of the hollow yam after PVA extraction does not change with the PVA content, and it is the same as that of the equivalent cotton yam. At a high filament percentage, the breaking elongation of the hollow yam is more than that of the cotton yarn.

Determining Mechanical Properties of Yarns and Two-Ply Cords from Single-Filament Data

The objective of this research is to construct a computer model that can predict the properties of flat yams, twisted yams, and twisted cords from single-filament data. In this model, a modulus versus strain curve is obtained by taking the derivative of the average stress-strain curve from single-filament tensile tests. The distribution of elongation to break is then fit to a Gaussian curve and a relationship is derived between filament elongation and bundle elongation in a twisted structure. Using the principle of conserva tion of energy, the forces from the surviving filaments at a specific strain are summed to yield the resulting force on a ply, which is then used to calculate the tensile force on the cord. The model also predicts elongation to break, tenacity at break, and initial modulus of yams and cords.

Fabric Softness Classification Using Linear and Nonlinear Models

In this study, the authors use linear and nonlinear models and yarn parameters such as CV%, hairiness, and surface softness to classify the softness of knitted fabrics (T-shirts) for comparison to human subjective evaluations. All classification rates are verified with a leave-one-out cross-validation technique. The results show 20% misclassification when using a linear model to sort samples into two classes (low and high). When sorting into three classes, the misclassification is 30%. When sorting T-shirt softness into three classes using a tree modeling technique and the surface response average (SRA) and maximum peak-to-valley height (Ry), it is possible to match the human data at a 65% rate. When using surface response parameters and measured yam properties to sort T-shirt softness into three classes, with tree modeling it is possible to classify 91% of the samples accurately based on the human data.

ジェットルーム製織条件がよこ糸物性に及ぼす影響

The mechanical properties of the fabrics woven by the jet loom are inferior to those of fabrics woven by the rapier or the shuttle looms, although not only the same textile weave was produced but also the same weaving yarns were used.Furthermore, the fabrics woven by the jet loom indicate paper-like features. These drawbacks of the fabrics woven by the jet loom would be caused by the marked deterioration of the yam properties during the weaving process.In this work, the influence of weaving conditions of an air jet loom (AJL) on the mechanical properties of weft yarn is investigated. As a result, it is found that the maximum strength and the modulus of elasticity are decreased during the weaving process. However, it is found that there is a weak correlation between the decrease in the modulus of elasticity and that in the strength. Moreover, it is found that the decrease in the modulus of elasticity would be caused by bending strain of the weft yarn, and the decrease in the strength would be caused by the production of the stress concentration in the weft yarn durig weaving.

A New Apparatus and Method for Tensile Testing at High Strain Rates

A high speed dynamometer is developed to measure the mechanical properties of linear textiles at strain rates similar to those encountered in manufacturing processes. Experiments based on 57 tex poly ( ethylene terephtalate ) yams permit us to investigate the influence of some important parameters such as inertia effects, transverse vibrations, clamping type, and sample gauge length on mechanical behavior. The clamping system and gauge length have a pronounced influence on the yam's properties, while the effects of inertia force and transverse vibrations are negligible.

Filament Pre-tension in Core Yarn Friction Spinning

Core yams are known to improve cotton yam properties. In this research, core yarns are spun by introducing filaments under tension into the yarn-forming zone of an ex perimental friction spinning apparatus. A 30-denier (3.3 tex) nylon monofilament and a black 75-denier (35f) nylon multifilament make up the core, and cotton fibers are used as the sheath. The effect of filament pre-tension on the structural parameters and mechanical properties of the core yarn is examined, and core yarn properties are com pared with those of equivalent 100% cotton yarns. The photographic and fiber tracing methods are used to consider the appearance of the yarns and the geometric position of the core in the core yarns. The results show that the appearance of the core yarn is similar to that of regular cotton yarns, with the exception of core yarns produced with 00 gf/fil pre-tension. Core yarn irregularity does not change with filament pre-tension, and it is less than that of cotton yam. Core yam strength significantly increases as filament pre-tension and filament percentage increase, and it is greater than that of cotton yarn. Core yarn elongation is less than that of cotton yarn at a low filament percentage and greater than that of cotton yarn at a high filament percentage.