PHYSICAL, THERMAL AND FUNCTIONAL PROPERTIES OF
Potravinarstvo Slovak Journal of Food SciencesPotravinarstvo Slovak Journal of Food Sciencesvol. 12, 2018, no. 1, p. 539-545doi: https://doi.org/10.5219/937Received: 16 May 2018. Accepted: 11 July 2018.Available online: 14 July 2018 at www.potravinarstvo.com 2018 Potravinarstvo Slovak Journal of Food Sciences, License: CC BY 3.0ISSN 1337-0960 (online)PHYSICAL, THERMAL AND FUNCTIONAL PROPERTIES OF FLOUR DERIVEDFROM UBI GEMBILI (DIOSCOREA ESCULENTA L.) TUBERS GROWN ININDONESIADiah Susetyo Retnowati, Andri Cahyo Kumoro, Ratnawati RatnawatiABSTRACTGembili (Dioscorea esculenta L.) tuber is one of the important food sources in term of cultural, nutritional and economicperspectives for the people in the Africa, Caribbean islands, Asia, and Oceania regions. The tubers can be eaten after beingboiled, roasted, fried or cooked. However, there is lack of information on the advanced utilizations of the tubers as rawmaterial in the manufacture of modern foods. This study aims to characterize the physical, functional and thermalproperties of Gembili flour, so that this information can be used as the basis in the development of novel foods. Themicrostructure, crystallinity, gelatinization temperature, swelling power and solubility of the flour were determined. Theelectron microscope observation revealed that Gembili flour consisted of smooth surface oval granules, which were lightbrown in color and having 23 µm average diameter. They are comprised of polygonals or some clusters of irregularfragments. Similar to most of tuber flours, Gembili flour also exhibited B-type crystallinity with approximately 31 3.7%crystallinity. The gelatinization temperature of Gembili flour was high and being comparable to that of cereal flour. Theenthalpy of gelatinization of Gembili flour (9.52 0.80 J.g-1) was comparable to that of Dioscorea alata. Unfortunately,Gembili flour exhibited low swelling power (3.90 0.01 g.g-1). The Gembili flour granules were highly soluble in water(11.07 0.05%). Based on those reported properties, Gembili flour can be a suitable raw material for the manufacture ofbakery, cookies, noodle and infant foods.Keywords: Dioscorea esculenta; flour; physicochemical properties; functional properties; thermal propertiesal., (2012) reported that the flour Gembili tubers planted inSriLankacontains10.39 0.15% moisture, 1.50 0.20% lipid, 9.02 0.65%protein, 2.10 0.20% ash, 2.33 0.15% fiber and 74.66 0.66% carbohydrate. Similarly, Ukpabi (2010) alsoreported a comparable proximate composition of the flourof D. esculenta grown in Nigeria. Unfortunately, yamtubers are known to contain different toxic substances thataffect both human and animals when they are consumed,despite their high nutritional values (Polycarp et al.,2012). Yang and Lin (2008) reported that the age, thecultivar, the geographic locality of a plant or the storagecondition after harvest could significantly affect its antinutritional content.In most parts of Indonesia, yams tubers are onlyconsumed as additional foods after being boiled, steamed,roasted, fried, baked or cooked. In contrast, yams areutilized as staple foods (Coursey and Ferber, 1979) andbeing important sources of ingredients for manufacturedfoods, which play a key role in the socio-economic andcultural lives of both growers and consumers in manyINTRODUCTIONYams are the edible tubers of numerous species of thegenus Dioscorea, which contain high content of starch asexcellent sources of caloric energy (Coursey and Ferber,1979). The primary cultivation areas of yams are in theWest, some parts of East, Central and Southern Africa(FAO, 2001), which produce about 95% of the totalworld’s yam production. The second largest yamsproducing areas are located in the Asian regions includingChina, Japan, Indonesia, Malaysia, Philippines andOceania. The third growing areas include the Caribbean,Mexico, and parts of Central America (FAO, 2001). Uwi(Dioscorea alata) and Gembili (Dioscorea esculenta L.)are the two main yam species commonly found inIndonesia, which can be harvested after being cultivatedfor 7 – 9 months. They are seasonal crops and generallyplanted in the end of September to October. The yellowingleaves and withered vines are strong indications of maturecrop, which is usually ready to harvest around May to July(Senanayake et al., 2012). Figure 1 (a) and (b) presentsthe Gembili plant and its tuber. Further, Senanayake etVolume 12539No. 1/2018
Potravinarstvo Slovak Journal of Food SciencesFigure 1 Ubi Gembili plant (a) and its tuber (b).tropical countries in West Africa, the Caribbean islands,Asia, and Oceania (Girardin et al., 1998). Primarily, theutilizations of yam have been limited to the preparation oftraditional dishes, such as pounded yam and porridges. Toprepare pounded yam, the yam tubers are usually sun-driedand powdered into flour for reconstituting into a stiff paste(amala), which is consumed with preferred vegetable soup(Awoyale et al., 2010). In regard to their fiber contents,yam flours also provide health benefits especially in theprevention of obesity, constipation, cardiovascular disease,diabetes and colon cancer (Chen et al., 2003).Interestingly, the absence of gluten has promoted yamflours as promising nutrition sources for those who sufferceliac disease (CD) (Van Hung and Morita, 2005).Considering that yam tubers are highly perishable andbulky, they are commonly processed into flour and starchas the most acceptable forms, in which they are usuallyconsumed or stored. These types of product provide ahigher possibility to prolong the supply of yam during theoff-season, thereby decreasing the loss during storage andreducing the cost for marketing and transportation(Coursey and Ferber, 1979). However, the potentialutilizations of yam flours have not been fully understood,mainly due to lack of general knowledge on the suitableprocessing techniques and product development as well asthe physicochemical and functional properties of theseplant materials. Flour characteristics, such as granule size,crystallinity, swelling power and solubility pattern, pastingbehavior and gelatinization properties are important in thedesign and manufacture of high quality food products(Aprianita et al., 2014a). This valuable information couldalso enable the food processors to modify the flours ifnecessary to accommodate the product and processingdemands. Interestingly, flour and starch from tubers androots can be used to substitute wheat flour in certain foodapplications, especially in the manufacture of biscuits andbakery products such as cookies, bread and cakes to reducethe production cost (Adeleke and Odedeji, 2010).Due to its large population, Indonesia requires arelatively high quantity of rice and wheat as the mainsources of carbohydrates, which is mostly fulfilled byimport and triggered a large financial burden. This highimport dependency is mainly caused by the unsuitability ofthe tropical climate for the cultivation of wheat in thiscountry. Improving our knowledge of the properties ofGembili tubers grown in Indonesia and many othercountries may result in the wider applications in the foodVolume 12or non-food industry. This will also contribute to thereduction of dependence on wheat flour as the main sourceof carbohydrate in Indonesia and other non-wheat growingcountries.Scientific hypothesisThe objective of this research was to determine thephysical, thermal, and functional properties of Gembili (D.esculenta) tuber flour as an important part of efforts towiden the possible applications of Gembili flour within thefood industries, particularly biscuits and noodles.MATERIAL AND METHODOLOGYSamples of plant materialThe freshly harvested 9 months age Gembili tubersgrown in Gunungpati, Semarang-Indonesia (geographicallocation: 7 5'13.39" S latitude, 110 21'27.69" Elongitude and 285 m altitude) were purchased from thetraditional market in Semarang-Indonesia, in the year2017.Chemicals and standardReagent grade of chemicals used for browningprevention (potassium metabisulfite) and Gembili flourcharacterization were the products of Merck-Indonesia andwere purchased from an authorized chemical distributor inSemarang-Indonesia. Analytical grade (petroleum ether)and standard (amylose) with a purity 98 % manufacturedby Merck (Germany) were used.Gembili flour preparationThe Gembili tubers were thoroughly washed with cleantap water to remove adhering soil and other undesirablematerials from the yam, and to reduce microbial growth onthe final product. They were peeled and trimmed toremove defective parts, washed, and grated withsemiautomatic machine to obtain thin slices ( 5 mm).Then, the slices were soaked in potassium metabisulfitesolution (0.075%) for 1 hour to prevent browning. Afterbeing washed with flowing water, the tuber slices werespread in a single layer on drying trays and dried in an airconvection oven at 40 ºC for 3 days and were subsequentlycrushed in a locally fabricated crusher, milled into flourwith hammer mill to obtain flour. The flour was thenpassed through -180 µm 250 µm sieves. Only theGembili flour retained on the 250 µm was used in this540No. 1/2018
Potravinarstvo Slovak Journal of Food Sciencesexperiment. The produced flour was stored in zip-lockpolyethylene bags and kept in covered plastic containers at20 C for further uses.Thermal propertiesThe Thermal analysis of flour Gembili was conducted bydifferential scanning calorimetry (DSC) using a Seikodifferential scanning calorimeter (DSC 210) (SeikoInstruments Inc., Chiba, Japan) equipped with a thermalanalysis data station and data recording software. Beforebeing subjected to DSC analysis, the Gembili flour of 20%water content was prepared by addition of 11 L deionizedwater using a microsyringe to 3 mg flour sample (drybasis) in the DSC pans, which were then sealed, reweighedand allowed to stand overnight at room temperature atroom temperature before analysis to ensure theequilibration of sample and water. The scanningtemperatures range and heating rate applied in this analysiswere respectively 25 – 300 oC and 10 oC.min-1, aspreviously used by Jayakody et al. (2007). Themeasurements were carried out under a dynamic nitrogenatmosphere (30 mL.min-1) in pierced aluminum pans toavoid condensation. In all measurements, the thermogramwas recorded with an empty aluminum pan as a reference.Flour properties analysisColor measurementThe color analysis was determined by Hunter notationsystem, which characterized by three color parameters asL*, a*, and b*. L* is a measure of the degree of lightnessfrom 0 (black) to 100 (white) color. The a* value states thered-green color (red is declared from 0 to 100 and greenis stated from 0 to -80). Finally, the b* value definescomponents on the yellow-blue axis value (0 to 70 foryellow and 0 to -70 for blue). The color of flours wasmeasured by Konica Minolta chromameter CR 400 assuggested by Akissoe et.al. (2003).Granule microstructureThe morphology and surface of Gembili flour granuleswere observed by scanning electron microscope (SEMJSM-6510 LA). Prior to SEM analysis, the flour sampleswere freed of granule clumps by sieving through a 250 mmesh and spread evenly on Cambridge type circularaluminum stubs with carbon electro-conductive doubledsided adhesive tape (Electron Microscopy Science,Hatfield, PA, USA) through a thorough inspection using astereoscopic microscope (Carl Zeiss, Stemi 2000-C, WekGottingen, Germany), before being coated with goldpowder (10 nm) for 60 s at 50 mA under vacuum using aEMS500 sputter coater (Electron Microscopy Science,Hatfield, PA, USA) to make the sample conductive. Thefreed clumps and gold coated flour granules within ahorizontal field width of 54.08 m were scanned andphotographed using the method and conditions assuggested by Jayakody et al. (2007), except themagnification of 2000x was used in this research.Swelling power and solubilityThe functional properties of Gembili flour, i.e. swellingpower and solubility were measured by the method ofAfoakwa et al. (2012). Swelling power is defined as theweight (g) of the swollen sediment per g of dry flour,while solubility is expressed as the percentage (by weight)of the flour sample that is dissolved molecularly afterbeing heated in water at 60 oC.Statisic analysisAll measurements were conducted in tripilicates and thedata obtained were expressed as mean Standarddeviation. Significant differences between the mean valuesat significance level p 0.05 were compared usingStudent s test using MS Excel version 2010.RESULTS AND DISCUSSIONColor observationGranule crystallinityThe Prior to X-ray diffraction analysis, the Gembiliflours were kept in a desiccator (at 25 oC) over saturatedK2SO4 solution (aw 0.98) up to sorption equilibrium (3weeks). X-ray diffractograms were obtained with a RigakuRPT 300 PC X-ray diffractometer (Rigaku-Denki Co.,Tokyo, Japan). The crystallinity patterns of Gembili flourswere recorded with X-ray diffraction at Bragg angle 2 between 4 – 40 o using a procedure previously describedby Jayakody et al. (2007). The crystallinity of the flourwas then quantitatively estimated following the method ofNara and Komiya (1983) by using a software package(Orion-version 6.0 Microcal Inc., Northampton, MA,USA).Color may attribute to the quality of foodstuffs material,such as the degree of maturity and spoiledness. Finally, thecolor of food also affects the consumer’s impressions. Thecolor characteristics (L*, a*, and b*) of Gembili tuberflour are presented in Table 1. As a comparison, the samecolor characteristics of wheat flour are also tabulated inTable 1.Visually, the Gembili flour is light brown in color and iseven darker than the commercial wheat flour as indicatedby L* value (Ukpabi, 2010). Lightness of flours can beaffected by browning reactions, which occur during itsprocessing, and this may have extensively affectedGembili flour and reduced its lightness. TheTable 1 Comparison of color parameters of Gembili flour and other flours.Color parameterThis workD. esculentaaL*87.22 0.1284.09 0.20a*1.84 0.00-3.06 0.03b*11.19 0.039.87 0.04abPolycarp et al., (2016), Ukpabi (2010).Volume 12541wheat flourb94.99 0.10-0.78 0.009.76 0.00No. 1/2018
Potravinarstvo Slovak Journal of Food SciencesFigure 2 Scanning electron microscopy (magnification 2000 ) of Gembili flour.yellowness/blueness index (b*) value observed forGembili flour was slightly higher than both commercialwheat flour and D. esculenta tuber flour grown in Ghana.This result confirms that Gembili flour appeared moreyellowish than commercial wheat and D. esculenta tuberflours. Apart from the inherent color pigments present inyams, yellowness in yam flours has also been linked tototal phenol content and the activity of polyphenoloxidase(Akissoé et al., 2003). The redness/greenness index (a*) ofGembili flour was far higher than commercial wheat flourand D. esculenta tuber flour grown in Ghana. If the colorof a food product is one of the important criteria, then theuse of native Gembili flour for its manufacture should beless considered. This is because usually white flours aremore preferred in various applications (as in white breadmaking). Theoretically, the substitution of wheat flourswith Gembili flour will reduce the whiteness, but willincrease the redness and yellowness of the flourcomposites (Aprianita et al., 2014a).appeared to be smooth and presented no evidence offissures. According to observation by Aprianita et al.(2014b), the smaller granule could be related to particleclusters. The average sizes of the oval structure and thepolygonal fragments were 23 µm and 6 µm, respectively.With smaller starch granules size, the digestibility ofGembili flour is fairly high (Szylit et al., 1978). Similarly,Jayakody et al. (2007) also observed that D. esculentastarch granules were polygonal in shape and the surfaceswere smooth. The starch granules size of D. esculentagrown in Kukula, Java-ala, and Nattala was between 3 to10 µm. In contrast, Aprianita et al. (2014b) observed abigger average granule size of D. alata flour, which a highproportion of larger granules of 345 µm and a smallportion of granules having 28 µm in size.X-ray diffraction patternsFigure 3 shows the crystallographic pattern of Gembiliflour. The pattern has strongest and broad peaks centeredat 17.1o and 24.2o, also has moderate peak at 14.9o, andweak peaks at 5.5o and 26o for 2 angles. The crystallinityof Gembili flour was around 31 3.7%. Thesecharacteristics indicate that Gembili flour falls in the Btype starch category (Brunnschweiler et al., 2005). Thisobservation is in good agreement with Jayakody et al.(2007) who explained that most of tuber flours, includingD. esculenta flours exhibit B type starch. In general,Granule morphologyThe scanning electron micrographs of Gembili flour isshown in Figure 2. It can be observed that the flourgranules are oval in shape, which consists of polygonal orirregular form of fragments. Some fragments werescattered and were likely to be the result of the breakdownof the bigger oval structure. The surface of the granulesFigure 3 X-ray diffraction pattern of Gembili flour.Volume 12542No. 1/2018
Potravinarstvo Slovak Journal of Food SciencesTable 2 The value of To, Tp, Tc and HGel of some Dioscorea flours.Botanical species To Tp Tcoo(origins)( C)( C)(oC)D. alata (Indonesia)62.00 1.7273.90 0.94 81.80 1.12D. alata (Brazil)71.50 0.3076.30 0.10 81.80 0.40D. esculenta (Indonesia)74.34 0.2079.65 0.50 85.83 0.10D. dumetorum (Nigeria)NANA72.80 2.79Low Protein Wheat60.60 1.8064.10 1.10 69.60 2.50High Protein Wheat57.80 1.5063.90 1.10 70.30 1.50Table 3 Swelling power and solubility of some Dioscorea flours.Botanical species (origins)Swelling power(g.g-1)D. dumetorum (Nigeria)D. bulbifera (Côte d’Ivoire)D. alata (Indonesia)D. esculenta (Indonesia)D. hispida Dennst (Indonesia)D. rotundata (Ghana)American Wheat2.22 0.012.60 0.013.00 0.233.90 0.014.67 0.1813.06 0.227.33 0.41starches with B-type of crystallinity, such as sweet potato,taro, arrowroot and cassava have higher digestibilitycompared to canna and konjac flours that have A-type ofcrystallinity (Liu et al., 2007). The high digestibility ofGembili flour is confirmed by high solubility value asdiscussed in the last section of this manuscript.Reference-1(J.g )7.40 0.8211.90 1.709.52 0.80NA5.70 0.805.00 0.90Aprianita et al. (2014b)Alves et al. (2002)This workOwuamanam et al. (2013)Aprianita et al. (2014a)Aprianita et al. (2014a)Solubility(%)Reference1.93 0.0110.20 0.066.51 0.0211.07 0.056.53 0.155.88 0.116.80 0.42(Abiodun et al., 2014)(Achyet al., 2017)(Harijono et al., 2013)This work(Kumoro et al., 20102)(Tortoe et al., 2017)(Chung et al., 2010)retort foods or foods that require heat stable viscosity(Tattiyakul et al., 2006).Swelling power and solubilityThe functional properties of the yam flours are importantsince they affect the end use of the flours. Swelling poweris the ability of flour to absorb water and hold it in theswollen flour granule, whereas the solubility of flour isrelated to the extent of leaching of amylose out of starchgranules during swelling and affected by intermolecularforces and the presence of surfactants and other relatedsubstances (Moorthy, 2002). Swelling and solubilitydepend on the characteristic of the flour granules, such asgranule size, the size distribution, amylose/amylopectinratio and mineral content (Singh et al., 2003). Bothproperties (swelling and solubilization) contribute to thesome of characterictics of food product and play importantrole in the determination of flour’s applications. Table 3presents the swelling power and solubility of somedioscorea flours at 60 oC.The swelling power of Gembili flour was lower thanother yam flours, such as D. rotundata grown in Africa(Tortoe et al., 2017) and D. hispida Dennst (Kumoro etal., 20102), but slightly higher than D. dumetorum(Abiodun et al., 2014), D. bulbifera (Achyet al., 2017)and D. alata (Harijono et al., 2013). According to Schochand Maywald (1968) flour classification, Gembili flourfalls in the highly-restricted swelling. Aprianita et al.(2014b) found that the swelling powers of D. alata varKrimbang flours were not significantly different attemperature range from 60 to 90 oC, at which the granulesmaintained their integrity. Lower value of swelling powerof starch of the Gembili flour might be attributed to theprotein-amylose complex formation in bean isolated starchand flour (Pomeranz, 1991). This characteristic isdesirable for the manufacture of value-added productsThermal propertiesThe disruption of solid structure can be studied byheating with the presence of small amount water throughdifferential scanning calorimetry (DSC). In this processes,the flour sample was heated at various temperature andheating rate. The onset (To), peak (Tp), conclusion (Tc)gelatinization temperatures and entahlpi of gelatinization( HGel) of Gembili flour obtained from DSC analysis, andthose of other dioscorea flours are tabulated in Table 2.The gelatinization temperature of Gembili flour obtainedin this research is slightly higher than that of D. alataplanted in East Java – Indonesia (Aprianita et al., 2014b),but significantly higher than D. alata farmed in Brazil(Alves et al., 2002) and D. dumetorum grown in NigeriaOwuamanam et al. (2013). A number of factors mayinfluence gelatinization temperature, including themolecular architecture of amylopectin, the formation oflipid complexes, degrees of crystallinity, and theproportion of crystalline regions (Aprianita et al., 2014b).The high initial gelatinization temperature of Gembili flourindicates that the granules were slow in swelling due tohigh resistant swelling of the starch granules (Alves et al.,2002) and therefore requires longer cooking time.Gelatinization temperature of Gembili flour was higherthan that of wheat flour (Aprianita et al. (2014a), whichindicates a higher stability of Gembili flour compared tothat of wheat flour (Srichuwong et al., 2005). TheGembili flour gelatinized at a high temperature range thatcould bring about its application as a thickening agent inVolume 12 HGel543No. 1/2018
Potravinarstvo Slovak Journal of Food Sciencesfunctional characterization of products obtained from yamtubers. Starch/Starke, vol. 54, no. 10, p. 4:10 476::AIDSTAR476 3.0.CO;2-6Aprianita, A., Vasiljevic, T., Bannikova, A., Kasapis, S.2014a. Physicochemical properties of wheat-canna andwheat-konjac composite flours. Journal of Food Science a, A., Vasiljevic, T., Bannikova, A., Kasapis, S.2014b. Physicochemical properties of flours and starchesderived from traditional Indonesia tubers and roots. Journal ofFood Science and Technology, vol. 51, no. 12, p. 5PMid:25477633Awoyale, W., Maziya-Dixon, B., Sanni, L. O., Shittu, T. A.2010. Nutritional and sensory properties of amalasupplemented with distiller’s spent grain (DSG). Journal ofFood, Agriculture and Environment, vol. 8, p. 66-70.Brunnschweiler, J., Luethi, D., Handschin, S., Farah, Z.,Escher, F., Conde-Petit, B. 2005. Isolation, physicochemicalcharacterization and application of yam (Dioscorea spp.)starch a thickening and gelling agent. Starch/Strarke, vol. 57,p. 107-117.Chen, H. I., Sheu, W. H. H., Tai, T. S., Liaw, Y. P. 2003.Konjac supplements alleviated hypercholesterolemia andhyperglycemia in type 2 diabetic subjects - a randomizeddouble-blind trial. Journal of the American College .1080/07315724.2003.10719273PMid:12569112Chung, S. Y., Han, S. H., Lee, S. W., Rhee, C. 2010.Physicochemical and bread-making properties of air flowpulverized wheat and corn flours. Food Science andBiotechnology, vol. 19, no. 6, p. 5Coursey, D. G., Ferber, C. E. M. 1979. The processing ofYams. In Pluckett, D. L. Small-scale processing and storageof tropical root crops. Boulder, Colorado, USA : WestviewPress, p. 189-212. ISBN: 0891584174.FAO. 2001. FAO Production Yearbook 1999, Rome, Italy :FAO. 321 p. ISBN-13: 9789250045207.Garcia, M., Dale, N. 1999. Cassava root meal for poultry.Journal of Applied Poultry Science, vol. 8, no. 1, p. in, O., Nindjin, C., Farah, Z., Eshcher, F., Stamp, P.,Otokore, D. 1998. Effect of storage system and sproutremoval on post-harvest yam (Dioscorea spp.) fresh weightlosses. Journal of Agriculture Science, vol. 130, no. 3, p. 329336. https://doi.org/10.1017/S0021859698005322Harijono, E. T., Saputri, D. S., Kusnadi, J. 2013. Effect ofblanching on properties of water yam (Dioscorea alata) flour.Advance Journal of Food Science and Technology, vol. 5, no.10, p. 1342-1350. https://doi.org/10.19026/ajfst.5.3108Van Hung, P., Morita, N. 2005. Physicochemical propertiesand enzymatic digestibility of starch from edible canna(Canna edulis) grown in Vietnam. Carbohydrate 1016/j.carbpol.2005.04.021Jayakody, L., Hoover, R., Liu, Q., Donner, E. 2007. Studieson tuber starches. II. Molecular structure, composition andphysicochemical properties of yam (Dioscorea sp.) starchesgrown in Sri Lanka. Carbohydrate Polymers, vol. 69, no. 1,p.148-163. https://doi.org/10.1016/j.carbpol.2006.09.024such as noodles and composite blends with cereals(Garcia and Dale, 1999).The solubility of Gembili flour is higher than any otherdioscorea flours reported in the literature. The value iseven higher than solubility of American wheat flour(Chung et al., 2010). A higher value of solubility of floursignifies an improved digestibility. The high digestibilityof Gembili flour might be beneficial for food preparationsespecially for infants and the elderly who require morereadily digestible food (Snow and O’Dea, 1981).CONCLUSIONA comprehensive characterization of physicochemical,thermal and functional properties of Ubi Gembili(Dioscorea esculenta L.) flour has been successfullycarried out. The Gembili flour was light brown incolor andwas darker than commercial wheat flour. The Gembiliflour granules were smooth surfaced oval structure having23 µm average diameter, which comprised of polygonal orsome clusters of irregular fragments. In accordance withtypical tuber flours crystallinity, Gembili flour alsoexhibited B-type crystallinity with approximately31 3.7% crystallinity. The gelatinization temperature ofGembili flour was high and being comparable to that ofcereal flour. The enthalpy of gelatinization of Gembiliflour (9.52 0.80 J.g-1) was comparable to that of D. alata.Inherent with its crystallinity, Gembili flour exhibited lowswelling power (3.90 0.01 g.g-1). As expedted, the smallsize Gembili flour granules were highly soluble in water(11.07 0.05%). The low swelling power, but highsolubility and gelatinization temperature suggests thatGembili flour is suitable for use as a raw material for themanufacture of bakery, cookies or noodle with hard biteand chewy texture and infant foods.REFERENCESAbiodun, O. A., Akinoso, R., Oluoti, O. J. 2014. Changes infunctional and pasting properties of trifoliate yam flour duringstorage. Journal of Applied Science & s://doi.org/10.4314/jasem.v18i2.26Achy, J. Y., Ekissi, G. S. E., Koffi, P. K. B., Koné, F. M. T.,Kouamé, L. P. 2017. Effect of boiling and baking times on thefunctional properties of aerial yam (Dioscorea bulbifera)flours cv Dugu-won har vested in Côte d’Ivoire. InternationalJournal of Agronomy and Agricultural Research, vol.10, no.2, p. 1-17.Adeleke, R. O., Odedeji, J. O. 2010. Functional propertiesof wheat and sweet potato flour blend. Pakistan Journal 0.3923/pjn.2010.535.538Afoakwa, E. O., Budu, A., Asiedu, S., Chiwona-Karltun, C.,Nyirenda, D. B. 2012. Viscoelastic properties andphysicfunctional characterization of six high yielding cassavamosaic disease-resistant cassava (Manihot esculenta Crantz)genotypes. Journal of Nutrition and Food Science, vol. 2, no.2, p. 129.Akissoe, N., Hounhouigan J., Mestres C., Nago M. 2003.How blanching and drying affect the colour and functionalcharacteristics of Yam (Dioscorea cayenensis-rotunda) rg/10.1016/S0308-8146(02)00546-0Alves, R. M., Grossmann, M. V., Ferrero, C., Zaritky, N. E.,Martini, M. N., Sierakoski, M. R. 2002. Chemical andVolume 12544No. 1/2018
Potravinarstvo Slovak Journal of Food SciencesKumoro, A. C., Retnowati, D. S., Budiyati, C. S.,Manurung, T. and Siswanto. 2012. Water solubility, swellingand gelatinization properties of raw and ginger oil modifiedgadung (Dioscorea hispida Dennst) flour. Research Journalof Applied Sciences, Engineering and Technology, vol. 4, no.17, p. 2854-2860.Liu, Q., Donner, E., Yin, Y., Huang, R. L., Fan, M. Z. 2006.The physicochemical properties and in vitro digestibility ofselected cereals, tubers, and legumes grown in China. g/10.1016/j.foodchem.2005.08.008Moorthy, N. S. 2002. Physicochemical and functionalproperties of tropical tuber starches: A review. Starch 10.1002/1521-379X(200212)54:12 559::AIDSTAR2222559 3.0.CO;2-FNara, S., Komiya, T. 1983. Studies on the relationshipbetween water saturated state and crystallinity by thediffraction method for moistened potato starch. Starch, r.19830351202Owuamanam, C. I., Iwuoha, C. I., Onuegbu, N. G., Ogueke,C. C., Nwosu, J. N. 2013.Quality characteristics of processedflours from trifoliate yam (Dioscorea dumetorum) asinfluenced by steeping and boiling in varying concentration ofTrona solution over time. American Journal of g/10.
excellent sources of caloric energy (Coursey and Ferber, 1979). The primary cultivation areas of yams are in the West, some parts of East, Central and Southern Africa (FAO, 2001), which produce about 95% of the total world’s yam production. The second largest yams p
Physical Properties of Minerals Physical properties of minerals are controlled by chemical composition and structure So, samples of same minerals exhibit the same properties Thus physical properties can be used to identify minerals Physical properties can be grouped into four categories Introduction to Mineralogy, Second edition
Energies 2018, 11, 1879 3 of 14 R3 Thermal resistance of the air space between a panel and the roof surface. R4 Thermal resistance of roof material (tiles or metal sheet). R5 Thermal resistance of the air gap between the roof material and a sarking sheet. R6 Thermal resistance of a gabled roof space. R7 Thermal resistance of the insulation above the ceiling. R8 Thermal resistance of ceiling .
thermal models is presented for electronic parts. The thermal model of an electronic part is extracted from its detailed geometry configuration and material properties, so multiple thermal models can form a thermal network for complex steady-state and transient analyses of a system design. The extracted thermal model has the following .
Physical Science Reading and Study Workbook Level B Chapter 2 17 Section 2.2 Physical Properties (pages 45-51) This section discusses physical properties and physical changes. It also explains how physical properties can be used to identify materials, select materials, and separate mixtures. Reading Strategy (page 45)
Thermal Transfer Overprinting is a printing process that applies a code to a flexible film or label by using a thermal printhead and a thermal ribbon. TTO uses a thermal printhead and thermal transfer ribbon. The printhead comprises a ceramic coating, covering a row of thermal pixels at a resolution of 12 printing dots per mm
Thermal Control System for High Watt Density - Low thermal resistance is needed to minimize temperature rise in die-level testing Rapid Setting Temperature Change - High response thermal control for high power die - Reducing die-level test time Thermal Model for New Thermal Control System - Predict thermal performance for variety die conditions
Numeric Functional Programming Functional Data Structures Outline 1 Stuff We Covered Last Time Data Types Multi-precision Verification Array Operations Automatic Differentiation Functional Metaprogramming with Templates 2 Numeric Functional Programming Advanced Functional Programming with Templates Functional Data Structures Sparse Data Structures
Latent Intrinsic Physical Properties Physics Interpreter. Mass Material Volume. Visual Intrinsic Physical Properties. Tracking. Physical Laws. Figure 2: Our model exploits the advancement of deep learning algorithms and discovers various physical properties of objects. We supervise all levels by automatically discovered observations from videos.
