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WHEAT.pptx
- 1. WHEAT FLOUR TESTING METHODS Prof.Dr.rer.agr. BDR Prasantha Dept. of Food Science & Technology Faculty of Agriculture University of Peradeniya
- 2. Moisture Content Asmall sample of flour 2–3 g The sample is heated in an air oven at 130 o C for 1 h OR at 100 oC for 5 h MC of 12-14%isideal for storage
- 3. Other Moisture tests Electrical conductivity methods MW NIR techniques
- 4. Ash Content Asample of flour 3–5 g The sample is heated at 585 °C in an ash oven Ash content indicates milling performance Ash in flour can affect color
- 5. Protein Content Sampleof flour 0.15–0.20 g Use Combustion Nitrogen Analyses (CNA) Drop the sample into 952 °C Amount of N released convert to the protein content Higher protein content requires more H2O and longer mixing time to achieve optimum dough consistency
- 6. Falling Number Sample of7 g + 25 ml water in glass falling number tube Stirrer and shaken to form a slurry Gelatinize the starch in a 100 oC hot water bath Time taken to drop the stirrer through the paste as FN F N=Stand(s)+Stirring(s)+Fallingt i m e F N= 5s +55s +240s=300
- 7. Falling Number Cont… FN - index of enzyme activity in a seconds Measures the effects of sprout damage High FN > 300 s - minimal enzyme activity and High quality wheat flour good for bread Low FN < 250 s - substantial enzyme activity High enzyme activity high sugar and little starch High falling number enzymes can be added to the flour Low falling number enzymes cannot be removed from the flour and it is unusable sprout damage
- 8. Color Typical whiteflour L* value +92.5 whiteness a* value –2.4 green b* value +6.9 yellow Bright white color flour is more desirable for many products
- 9. Single Wheat KernelCharacterization Sample wheat kernels 12–16 g Remove broken kernels, weed seeds, and foreign material kernel weight and diameter, MC and kernel hardness
- 10. Laboratory Flour Milling Determinesflour yield Makes flour for other tests
- 11. Particle Size Distribution Use series of standard sieves Particles classified into size ranges Particles of size < mesh openings 60 50 40 30 20 10 0 >200 200-150 150-100 100-40 <40 Range of particle size(µm) Sample retain (%) M e a nparticlesizeofB g360 M e a n particlesizeofAt405
- 12. Damaged Starch Microscopicstudy of damage SG - red coloration with Congo Red, Hessian Bordeaux staining or Iodine absorption by DSG UV-VIS spectrophotometry at 600 nm amount of maltose released
- 13. Wet Gluten Content Flour sample - 10 g into the Glutomatic chamber Sample washed with a 2% salt solution for 5 min. Wet gluten is removed and centrifuged Wet gluten index eg: 35% w.b - high protein, strong gluten 23% w.b - low protein
- 14. Brabender Farinograph Measuresflour water absorption and dough strength Sample size – 50 g or 300 g Water is added to the flour and mixed to form dough
- 15. Brabender Farinograph Farinographpredicts texture characteristics of the product Ex: Strong dough mixing are related to firm product texture
- 16. Application of Farinograph Measure the water absorption of flours Determine the wheat suitability of flour Development time Dough stability Degree of softening Verify flour blends Other application eg: chocolate, chewing gum, fish, etc.
- 17. Extensograph Visco-elastic recorder Measures dough extensibility and resistance to extension Flour sample 150 g Mix flour + H2O + salt Dough preparation Dough shaped into cylinder Dough is stretched until rupture Force exerted is measured
- 18. Extensogram Resistance toextension Extensibility = curve length (mm) Area below the curve: energy Ratio number = Resistance Extensibility
- 19. Testing flour qualityby Extensograph Extensigraph determining Gluten strength Effect of fermentation time Effect of additives on dough performance Ascorbicacid,enzym es ,emulsifiersetc. Testing flour quality Stretching behavior of the dough Baking characteristics Influence of flour additives Rheological optimum
- 20. Extensogram profiles ofdifferent flour quality Strongflour Extensible,elasticdough Suitabilityforlong fermentation Goodforlowvolumebaking products Rigid,t o u g hd o u g hstructure Poorextensibility Doughhardlyrises Smallpiecesofdough W e t ,plasticd o u g h Softdough Narrowfermentation Doughtendstospread Smallbakingvolume
- 21. Alveograph Measures doughstrength Determine Firmness; Extensibility; Elasticity and Baking strength 3D extension of a dough sample Water + salt + flour (250 g) 4.5 cm circular dough patty formed Air blows Expands into a bubble P inside the bubble is recorded Eventually breaks the bubble
- 22. Alveogram This proceduresimulates Deformation of the dough from yeast due to gas Chemical leavening
- 23. Alveogram Weak gluten flour lowP(strength of gluten) and long L (extensibility) cakes andconfectionery products Strong gluten flour highP values Good for breads
- 24. Mixograph Measures flourwater absorption and dough mixing characteristics - indicates protein quality Flour sample - 35 g Water + Flour dough in a bowl Dough mixing torque records Weak Gluten Flour Strong Gluten Flour
- 25. Mixogram Test smallquantities of flour Flour water absorption For baking tests 0 = weak dough strength 7 = strong dough strength Unacceptable LowProtein<10% LongPeakT i m e Unacceptable LowProtein<10% ShortPeakT i m e Acceptable Protein,1 0-13% PeakT i m e2.2-2.8m i n
- 26. Visco Amylograph Floursample - 65 g + 450 ml of H2O Slurry is stirred from 30 -95 °C rate of 1.5 °C min-1 Measures flour-starch properties and enzyme activity sprout damage Asian noodle flour of medium-high peak viscosity is preferred Texture Sprouted Wheat Flour Sound Wheat Flour
- 27. Baking Test –PanBread Formula (MC 14%) Flour - 100 g Dry yeast -1 g Sugar - 6.0 g Salt - 1.5 g Shortening - 3.0 g Water variable 58 - 70 g Malted barley - 0.2 g Additional ingredients may include oxidants or dough conditioners In baking formulas, ingredients are expressed as flour weight% Panbreaddoughis evaluated Strength,extensibility,andstickiness Weighedandmeasuredforvolume Scoredforexteriorappearance,internal uniformcrumbgrain,andtexture
- 28. Baking Test –HearthBread Baguette Pre-ferment Dough Formula Flour - 120 g Water - 80 g Salt - 2.5 g Instant yeast - 0.2 g Baguette Dough Formula Flour - 1000 g Pre-ferment dough - 200 g Water - 680 g Salt - 22 g Instant yeast - 10 g
- 29. Baking Test –FlatBread Egyptian Baladi Flat Bread Formula (14% MC) Flour - 180 g 80-95%extraction Compressed yeast – 1.5 g Salt - 1.0 g Water – 65-70 g Flat bread such as TortillasinMexico,Chappatiin India,andShaobininChina Testprovidesinformationon processingperformanceof flour Stickinessofadoughisa significantfactorinflatbread production
- 30. Baking Test –Cookies Formula(14% MC) Flour - 40 g Sugar - 24 g Shortening - 12 g Solution of NaHCO3 - 0.32 g Solution of NH4Cl - 0.2 g Salt - 0.18 g NaHCO3 - 0.4 g Nonfat dry milk - 1.2 g Water Variable (0.3–2.1 ml) Top evaluated by visual examination of the pattern of cracks and “islands” on the top surface of the cookie Flour with low protein and weak gluten - high cookie spread and cracks on the surface, usually performs well for these products
- 31. Baking Test –SpongeCake Formula (14% MC) Flour - 100 g Egg - 100 g Sugar - 100 g Water - 40 g Batterconsistentviscosity SG: 25±1 g/ml; 30±1°C Evaluated for volume External characteristics - shape, crust color, and cake appearance Internal characteristics - cell uniformity, cell size, and cell wall thickness Texture Flour with low protein, low ash and weak gluten makes good quality sponge cake
- 32. Asian Noodles Test WhiteSaltedNoodles Flour - 1000 g Salt - 12 to 20 g Water - 280 to 400 g Additional ingredients that affect color or texture may be added: Eggs NaOH K2CO3 or Na2CO3 Starches Gums Texture is determined as hardness, springiness, cohesiveness, and chewiness with the Texture Analyzer