Effect Of Physical And Chemical Characteristics Of Some Wheat On The Quality Of Some Products:

Ahmed El-sayed Mohamed El-bardeny

Different wheat varieties which import for variousbaking industries were sUbjected to different analysis.Two main species 0:: wheat T. aesti v Urn and T. durum and their varieties C.W.R.S. three degree, AustralianCanadian Amber 3 degree and the Egyptian durum stork•swere chosen for studying the different factors affectingpasta industry in ]~gypt. Although semolina imported byprivate sector,tCapri, Roma, Buitoni .•) were subjectedto the same analysis. Results concerning the followingitems:1- Physical and chemical properties of wheat kernelsflour and semoltna.2- Conditioning lytng time.3- Pasta browning 4- Pasta quality.were discussed in detailes:Results could be summerize as follows:1- Physical and chemical characteristics of wheat flourand pasta: 1.1. Physical characteristics of different wheat varieties: Results showed that Egyptian durum storks showedhigher values for hectoliter weight l81.1 Kg/HL)and 1000kernel weight (53.75 g ) than that other hard wheat varieties.Canadian Amber grade 3 characterized by the highest vitreouspercentage (79.70%) followed by Egyptian stork’s(65.33%), while Australian soft wheat are without vitreousand has the highest hectoliter weight (84.0 Kg/HL).1.2. Chemical constituents of wheat kernels,flourand pasta: Egyptian stork’s flour had the higher ~oisture content(15.8%) which may be due to its higher water absorptionduring conditioning, while imported semolina moisturecontent ’was ranged between 11.8% and 12.0%.Imported semolina contained lower quantities of ashthan local durum. E9yptian stork’s flour ash content ishigher than aestivum varieties wheat flour. High ashcontent has negative effect on the colour of the producedmacaroni.Crude fiber ranged between 2.0-2.6% in the differentwheat varieties. Stork’s vitreous kernels showed the highestfiber content (2.6%) while Australian soft wheat hadthe lowest (2.0%). Pasta quality are affected by ashcontent and bran contamination.Durum wheats contained higher protein content thanaestivium wheats. Stork’s vitreous kernels had higherprotein content than starchy. The Egyptian durum wheatstork’s had 14.85% protein which was higher than T.aestivurn(13.60 and 8.84 for C.W.R.S. and Australian) and was lowerthan canadian durum wheat {15.69%}. The gluten contenthave good relation with total protein, canadian west redspring wheat showed the highest wet and dry gluten content(48.80 and 16.72%).the Australian flour had the lowest wet and drygluten (25.0 and IO.O%). In general dry gluten followedthe wet gluten up and down, storkls vitreous flour showedmore gluten content than starchy flour. Cooking qualityis related to protein content, it improves with increasingprotein content. So, patent flour from low protein ,australian wheat was not suitable for pasta production.Soluble protein fraction {alb. + glob.’ shows slightlydifference between different varieties and rangedbetween 13~49% and 16.61%. Gliadins represent the majorproportion of protein fractions for flour and semolina.Glutelins contents of flour were independent of the totalprotein content but differ among cultivars. T. aestivumwheat kernels had higher starch content than dururn varieties.Stork’s starchy kernels showed higher starch content(64.6%) than vitreous kernels (56.9%). The alpha-amylaseactivity for the extracted flours showed the same trendof the whole wheat kernels. Semolina alpha-amylase was13.39, 15.50 and 16.40 for Roma, Duitoni and Capri whichwas lower than stork’s {22.00}.The australian soft wheat and extracted flour had the lowest percentage of crude lipids (l.97 and 1.12%).The whole wheat kern~~ls had higher crude lipids content than the extracted flour or semolina because of the higher lipids content of the germ and bran.Tbe pigment content of T. aestivum varieties waslower than that of T. durum. Pigments content of Egyptiandurum flour (7.1 ppm) have the same trend of the importedsemolina (between 6.70 and 1.4 pp m ).11- Effect of conditioning lying time: The effect of cond1tioning lying time (1,~,12,18 and24 hrs.’ on the ext~action rate, chemical composition andrheological properties was studied.11.1. Effect of conditioning lying time on T. durum stork’s:Increasing lying time showed a slight decrease inextraction rate (72.09 to 71.78) ash content (from 1.00 to0.88%), non-reducinq sugars (from 1.75 to 0.98%), pigmentcontent (from 7.1 to 6.4 ppm J, and lipids content (from2.4 to 1.32%). In the same time moisture content andreducing sugars increased from (12.9 to 14.2%) and (0.38to 1.24%) respectively. Also, increasing conditioninglying time activate different hydrolysing enzymes. Alphaamylaseactivity increased in both wheat kernels ( from 13.27 to 32.00) and flour {from 11.75 to 16.57),non-proteinnitrogen increased from ~.156 to 0.305% due to increasingproteases activity. The rheological properties of doughshowed that dough development (1.75 min) arrival (0.5 min)and stability (5.1 min) were higher in the sample conditionedfor 5 h Water absorption (60.87%) and weakeningof dough (75 B.u) showed its lowest value after 5 hconditioning lying time. Therefore ”5 h conditioninglying time is preffered for Egyptian stork’s yield pastaof good quality.11.2. Effect of conditioning. lying time on T. aestivium(Australian wheat):”Conditioning lying time affected on the chemicalconstituents of wheat kernels and flour. Flour yield and ash content decreased (from 74.27 to 72.78%) and (from 0.77to 0.51%) respectively, while moisture content increased(from 13.9 to 14.3%) by increasing lying time. Also a positiverelation between browning, alpha amylase activity andnon-protein nitrogen was observed. Pigment amount showed arelation between pigment content and the extraction rateThe rheological properties of the dough showed thatwater absorption was low (57.0%) and dough stability washigh (4.7 min) at ~2 h. lying time. The mixing time andarrival time increased gradually by increasing conditioninglying time which indicate that T. aestivium contains strongergluten content than T. durum. Results showed that 12 hconditioning lying time is suitable for australian T.aestivium.111- Pasta browning : The obtained results showed that T. durum stork’s pasta was brown and had the highest grade colour value (lD.G) while pasta processed from imported semolina, Roma, Capri and Buiton! was yellow and had the lowest colour 3.5 ,3.6 and 3.3). T. aest Iv um pasta,1 Amoun and Mataria hadbrown and bale brown colour and lesser grade values thanstork’s. 8.4 and 4.1). Brownness in macaroni was attributedto varietal, bran contamination, enzymatic and non -enzymatic reactions. Both of these factors were discussed.~. durum stork’s pasta had the highest pigment loss duringprocessing ’51.41%), while Roma, capri and Buitoni had thelowest loss (22.24, 14.57 and 23.0%). Spaghetti processedfrom T. aestivti!r.had 35.12% and 37.69% pigment has lossfor Amoun and Mataria respectively. Due to Stork’s highest pigment loss during processing, stork’s spaghe”cti had the lowest p~gment content (3.45 ppm.) comparing with otherdurum spaghetties. The obtained results showed that lipoxidase activity is higher in Egyptian durum stork’s than that of the imported semolina. Also, apositive correlation between pigment loss percentage andbrownness during pasta processing was observed.IV- Pasta quality : Results of the reheological properteis showed that the semolina samples had the lowest water absorption value(between 50,0 and 50,9%) and its dough development time(D.D.T.’ was higher ~han other flour samples. Stork1sD.D.T. was the lowest one