authored by Biruk Gedif Worku*
Abstract
The textile industry is one of the most important sectors in Ethiopia and has grown from year to year. The extraction and processing of starch from different resources are one of the most important agro industries in the world. Starch is a product commonly used in textile industries as a sizing agent and is mainly sourced from food crops. Those food crops are mostly edible by human beings. Therefore, alternative starch sources of materials are required. This research focused on extracted starch from white lupine seed which is not edible. Two extraction methods are used namely cold and hot steeping. From those cold steeping is much better than hot to get a quality starch which is comparable with the existing starch in the market like maize, white, etc. starches. After applying the extracted whit lupine starch in textile sizing, the tensile strength of warp yarn was not a significant difference. After sizing using extracted white lupine starch which is a hot and cold steeping method the average tensile strength was 320.9 cN and 338.3cN respectively and the average elongation of yarn was 4.27 % and 4.21% respectively achieved. The size pick-up % warp yarn in the case of hot and cold steeping is 10.64 and 14.85 respectively was achieved.
Keywords: Starch; Extraction; Textile; Sizing; White lupine seed
Introduction
The textile industry is one of the most important sectors in Ethiopia. Because the Ethiopian government has spearheaded the sector as one of the key priority sectors for which has contributed to the multiple aspects towards the economy of Ethiopia such as, investment, occupation and export. This is supported by the creation of various industry policies and incentives to attract foreign direct investors [1-3].
The textile industry mainly three basic sections those are spinning process, weaving and finishing. Under weaving, the sizing process is the heart of its. Sizing in weaving production serves to protect the warp yarns during the weaving process. Protective sizing agents help the yarn to withstand high mechanical stress during weaving. Starch material is one of the most important materials in textile industries to develop textile capability (strength, elasticity and surface strength) reduce friction in the weaving process and improve the feel and appearance of the fabric. They do this by improving the wear resistance of the warp threads and by reducing fiber abrasion. This prevents yarn breakage during weaving and thus machinery downtime. Furthermore, sizing improves the appearance of the woven fabric [4-8].
The invention relates to the use of native chemically unmodified amylose-type starch as a sizing agent for natural and/or synthetic textile yarns and textile blended yarns as well as to a process for sizing textile yarns using these starch products. The invention furthermore relates to the use of chemically modified amylose-type starch as a sizing agent for natural and/or synthetic textile yarns and textile blended yarns as well as to a process for sizing textile yarns using chemically modified amylose-type starch products [9].
The sizing agent must adhere strongly to the fiber, and its film properties should be largely independent of the climatic conditions, especially atmospheric humidity, and be unaffected by fiber finishes and sizing additives. The elongation of the warp thread should not be reduced by the presence of the sizing agent [8,10].
After the gray cloth has been woven, the task of the sizing agent is complete. As it would usually have a deleterious effect on subsequent finishing processes, it must be completely removed. Removal is simple in the case of cold-water-soluble sizing agents, but starch products that are insoluble in cold water require preliminary enzymatic or oxidative breakdown before the de-sizing stage. The removal of the sizing agent may pose special wastewater treatment problems in finishing plants.
The growth of synthetic fibers and the developments in weaving technology has accelerated the development of synthetic sizing agents. The sizing agent to be used must satisfy different requirements, such as good penetrativeness, good adhesiveness, good film-forming properties and the ability to form an elastic sizing film. A suitable sizing agent imparts to the sized yarn desirable properties, such as a high wear resistance (abrasion resistance), a high weaving efficiency and good washing-out properties of the woven textile product [11-13].
The most important sizing agents are potato, maize, and tapioca starches. Wheat, rice, and sago starches are also used. The characteristic properties of these starches are determined by the amylose/amylopectin ratio, the degree of polymerization of these two constituents, and the size and fine structure of the starch grain. These parameters determine the swelling and solution behavior, and also the properties of the film [6,8,14].
Natural starch is insoluble in cold water because of the hydrogen bonds linking parallel polymer chains. The starch is brought into “solution” by heating. The starch grains first absorb water until the swelling is at its maximum. Above a certain temperature, characteristic for each type of starch and known as the gelatinization temperature, the starch grains burst and form a gel. The viscosity increases to a maximum and then decreases asymptotically to a limiting value as the solubilized polymer molecules disperse. Complete solubilization of the individual molecules of a starch grain only occurs above 100 °C. The viscosity value is important in size application, as it has a considerable effect on the amount of liquor pickup [15,16].
Now, natural and manmade starch materials are used as a sizing agent in the textile application for increasing the yarn strength. Among these maize starch from natural origin is widely used for this application which is a common edible food by human beings. Because of its wide application, still there is a shortage of starch in the market. Therefore, extraction and characterization of starch from different sources is a great concern.
This research work focused on the extraction of starch from lupine which is not commonly used as food and has a lower cost to supplement the existing costly starch-based products in the country, specifically for textile industries.
Materials and Methods
Materials, equipment’s and chemicals
Warp yarn, white lupine (lupines Albus) seed, FTIR machine, Filter paper (polyester fabric), Beaker, Stove, Thermometer, litmus paper (Ph meter), Dryer, Laboratory Sizing Machine, balance, Portable yarn strength tester (single yarn strength tester), Wet milling machine, high- speed Stirrer and abrasion tester are required. Additionally, chemicals like iodine solution, sodium hydrosulphide are used as anti-oxidizing agents during extraction.
Methods
For this research, it was used two extraction methods, hot steeping and cold steeping processes. Generally,
Cleaning: The white lupine seed from stones, cobs, dust particles and foreign material was done
Steeping: Well-conducted steeping is an important prerequisite for high yield and good starch quality. At first, the purified white lupine kernels are transferred into a tank containing steep water. This step is conducted at 50 °C and lasts about 24 to 36 hours. Steeping tanks are commonly series- connected and operated by the counter flow principle. For optimal steeping conditions, steep- water is kept at pH 4 by the addition of sulphuric acid or hydrochloric acid and treated with Sulphur dioxide. These conditions guarantee optimal water absorption of the lupine kernel, controlled fermentation by lactic acid bacteria and loosening of the protein matrix. At the same time, steep water causes the softening of the kernels and the release of soluble. Growth of lactic acid bacteria suppresses unwanted microorganisms such as yeasts, molds and other bacteria. During steeping the size of kernels nearly doubles and the water content increases from 15% up to 45%.
Fine grinding and extraction: The germ removal step is followed by fine grinding in an impact mill to completely disrupt the cells of the endosperm and release the starch granules. The resulting suspension is led over bend green cascades for separation from fiber and other maize components. The starch milk, which contains the protein fraction, the so-called gluten, passes through. The bend screen cascades are connected in series. For complete washing out of the starch and separation of the fibers, they are operated by the counterflow principle. Additionally, washing water is added to the last process stage.
Starch refining: The starch milk, which still contains approximately a minimum amount of protein and fibers after separation, is then refined in a multi-step cyclone plant. The last stage of the multi-step cyclone plant is the only step of the wet milling process where freshwater is added.
Dehydration and drying: The refined starch milk, having a water content of approximately 65 %, is dehydrated in peeler centrifuges to a residual water content of about 40%. The layer of the filter cake is colored yellow and contains high amounts of protein. It is reintroduced into the process. Pure starch is finally dried.
The two types of extraction methods are:
1. The hot steeping method is the process of socking the raw material by hot water (Figure 1).
2. The cold steeping method is a process of socking the raw material by the cold water (Figures 2-4).
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