Grain Processing Technologies Class 12 October 19 th, 2017 Corn and oat processing technologies Prof. Dr. Nathan Levien Vanier
Corn production Source: FAO (2017)
Corn utilization
Corn processing Freshly harvested corn Cleaning, drying and storage processes Dry milling Wet milling Nixtamalization Flaking grits Brewing grits Other grits Flour Germ Bran Starch Germ Bran Soaking water Nixtamalized flour Tortilla Chips
Product classification according to particle diameter Source: Eckhoff, Dry Milling, In: Encyclopedia of Grain Sci., 2004.
Milling quality depends on maize/corn structural characteristics
Corn endosperm Source: Delcour and Hoseney, Principles of Cereal Science, Chapter 1, 2010, 260p.
Corn endosperm characteristics
Dry milling Corn Cleaning and selection Milling Selection and sieving Whole maize flour
Dry milling
Dry milling Corn grains Cleaning and selection Conditioning (21% moisture) Degermination Milling Selection and sieving Germ Pericarp Selection Milling Oil extraction Starch/Glucose Alcohol Flour from degerminated maize/corn
Conditioning step details
Conditioning step details Addition of 6% to 8% of water in relation to grain mass Tempering for 10 to 40 min.
Corn degerminator
Milling yield of 9 hybrids using a Beall-type degerminator Source: Eckhoff, Dry Milling, In: Encyclopedia of Grain Sci., 2004.
Micronization treatment of corn flour with infrared at different time-temperature conditions (a) control; (b) infrared at 159 C/173 s/40%; and (c) infrared at 166 C/164 s/40%. Fonte: Deepa & Hebbar et al., Journal of Cereal Science, v. 60, p. 569-575, 2014.
Micronization treatment of corn flour with infrared at different time-temperature conditions Increased conservability Fonte: Deepa & Hebbar et al., Journal of Cereal Science, v. 60, p. 569-575, 2014.
Wet milling 1) Soaking Bins with water recirculation set at 52ºC. Time varies from 20 to 48 h.
Wet milling 1) Soaking 2) Germ removal Mechanical shearing and cutting.
Wet milling 1) Soaking 2) Germ removal Mechanical shearing and cutting.
Wet milling 1) Soaking 2) Germ removal Mechanical shearing and cutting. Separation using hydrocyclone.
Wet milling 1) Soaking 2) Germ removal 3) Fiber separation
Wet milling 1) Soaking 2) Germ removal 3) Fiber separation
Wet milling 1) Soaking 2) Germ removal 3) Fiber separation 4) Protein separation
Wet milling 1) Soaking 2) Germ removal 3) Fiber separation 4) Protein separation Separation by density profile using a disc centrifuge.
Wet milling 1) Soaking 2) Germ removal 3) Fiber separation 4) Protein separation 5) Starch
Wet milling 1) Soaking 2) Germ removal 3) Fiber separation 4) Protein separation 5) Starch Separation using hydrocyclone.
Nixtamalization Maize + Ca(OH) 2 Cooking for 25-30 min + hydration for X time Drainage of solution Germ removal Milling Drying Frying Nixtamalized massa Sieving Chips Cooking Table Tortillas Nixtamalized maize flour
Mexico - 1836
Nixtamalized maize after water drainage
Nixtamalization
Nixtamalization research results Calcium content in maize fractions and nixtamalized flour. Fonte: Cornejo-Villegas et al., LWT, v. 53, p. 81-87, 2013.
Nixtamalization research results 149 μm 420 μm Fonte: Palacios-Fonseca et al., Journal of Food Engineering, v. 93, p. 45-51, 2009.
Nixtamalization research results Fonte: Palacios-Fonseca et al., Journal of Food Engineering, v. 93, p. 45-51, 2009.
Corn flakes
Oat processing Oat grains Cleaning and selection Dehusking Stabilization (toasting) Flakes production Cutting Partial milling Flakes production
Cleaning and selection Fonte: Ganbmann e Vorwerck, In: The oat crop, Ed. Chapman & Hall, 1995.
Oat processing Oat grains Cleaning and selection Dehusking Stabilization (toasting) Flakes production Cutting Partial milling Flakes production
Dehusking Rotary impact mill
Greater hulling degrees are obtained at low moisture levels Fonte: Ganbmann e Vorwerck, In: The oat crop, Ed. Chapman & Hall, 1995.
Hulling degree as a function of peripheral speed of a Rotary impact mill Fonte: Ganbmann e Vorwerck, In: The oat crop, Ed. Chapman & Hall, 1995.
Oat processing Oat grains Cleaning and selection Dehusking Stabilization (toasting) Flakes production Cutting Partial milling Flakes production
Stabilization 83-100 ºC for ±30 min
Moisture level may be increased for successfull stabilization of oats Fonte: Ganbmann e Vorwerck, In: The oat crop, Ed. Chapman & Hall, 1995.
Oat processing Oat grains Cleaning and selection Dehusking Stabilization (toasting) Flakes production Cutting Partial milling Flakes production
Cutting is performed in a drum with knives attaches Fonte: Ganbmann e Vorwerck, In: The oat crop, Ed. Chapman & Hall, 1995.
Oat processing Oat grains Cleaning and selection Dehusking Stabilization (toasting) Flakes production Cutting Partial milling Flakes production
Flakes production 94-100 ºC for ±30 min
Effects of tempering time and temperature on flake thickness Fonte: Gates et al., Journal of Cereal Science, v. 48, p. 288-293, 2008.