Milling practices
- 1. MILLING PRACTICES (Dry and Wet milling) OF DIFFERENT LEGUMES BY: HITESHINI .T.Y. ROLL NO: 20FST30 COLLEGE: ST. JOSEPHS COLLEGE (AUTONOMOUS)
- 2. CONTENT •INTRODUCTION TO LEGUMES AND MILLING •METHODS OF MILLING (GENERAL) •MILLING PRACTICES IN DIFFERENT LEGUMES • REFERENCES
- 3. LEGUMES • A legume is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is a called a pulse. • Most commonly used legumes or pulses are pigeon pea, bengal gram , green gram and black gram etc. • Legumes are grown agriculturally, primarily for human consumption, for livestock , and as soil-enhancing green manure. • Pulses are very good source of protein of 20- 30%., which helps to supplement cereal diets, improving their protein nutritive values. • Carbohydrates: Food pulses contain about 55-60 per cent of total carbohydrates including starch, soluble sugars, fibre and unavailable carbohydrates. • Minerals: Pulses are importantly sources of calcium, magnesium, zinc, iron, potassium and phosphorus. • Vitamins: Pulses contain small amounts of carotene, the provitamin A. https://www.google.com/url?sa=i&url=https%3A%2F%2Fbrainly.in%2Fquestion%2F1357538&psig=AOvVaw1hCyfiCq5Jckc9UWDrEToO&ust=1619019399 000000&source=images&cd=vfe&ved=0CAMQjB1qFwoTCOCgnZSVjfACFQAAAAAdAAAAABAD
- 4. Legumes Oilseed Legumes Higher fat and calorie content • Soy beans • Peanuts Pulses Dried ,edible seed of grain legumes: low fat ,high fiber, high protein Fresh Legumes Eaten as fresh vegetable • Fresh beans • Fresh peas pods COMMON BEANS A type of pulse many varieties • Black beans • Lupin beans • Kidney beans Lentils Dry Peas Chickpeas
- 5. MILLING SIZE REDUCTION The removal of the outer husk and splitting the grain into two equal halves is known as milling of pulses . Basic processes in milling are cleaning, grading, conditioning, de husking, splitting, and separation, polishing and bagging or packaging. To facilitate dehusking and splitting of pulses alternate wetting and drying method is used . Mill powder tech
- 6. Drying is done after this process to attend uniform temperature STEP 1 : CLEANING AND GRADING Machines involved : Reciprocating air screen cleaner , rotary drum cleaner ,grain grading machine.
- 7. STEP 2: PITTING Crack and scratch Oil or water penetration Machines used: emery roller, destoners.
- 8. STEP 3. LOOSENING HUSK Effectiveness of this operation decide the final recovery of grains. Methods under lossening husk: 1. WET method : water involved (grains soaked) for 4-12hours , addition of red earth for 12-16 hours , sun dried to attend 10-12% moisture content . 2. Dry method: oil involved (linseed oil, edible oil) for 12 hours and dried by spreading on the cemented floor . CONDITIONING SOAKED AND DRIED GRAINS INVOLVED. 1. 3-5% WATER ADDED TO GRAINS FOR 8 HOURS AND DRIED . 2. THIS PROCESS IS DONE FOR 2-4 DAYS AND DRIED .
- 9. STEP 4. DEHUSKING OF GRAINS • Removal of husk . • Machine used: roller dehuskers (roller coated with caborandom ), Vertical stone grinder • 10-25 % husk removed in one pass. • after this process , we see cotelydons , whole grain , husk , powder , which are screened and separetd by seiveing • Around 2-8 times the grains are passed through roller miller until the husk is removed .
- 10. Step 5. Splitting of grains • Involves – loosening the bond between the cotelydons , splitting due to impact. • Addition of water (1- 5kg/quintal ) to dehusk pulse grain (gota). • Rested for 2-12 hours and dried for 4-8 hours(sun drying). • Grains are splitted by hitting on hard surface . • Machines used : Under run disc sheller (URD), Impact machine,roller machine, hitting against the metal sheet at discharge side of bucket elevator .
- 11. Step 6: Polishing of grains • Impart with glazing appearance to improve consumer acceptance and market value. • Removal of powder/dust on the grains by addition of water, oil,soapstone powder etc. • Types : 1. WATER POLISH : 1-1.5KG/QUINTAL (channa,massor,urad) 2. BUFF POLISH : 2-2.5KG/QUINTAL of water with 200-250g of oil . 3. NYLON POLISH :soapstone or selkhari powder (1-1.5kg/quintal) with water (1-1.5kg/q) 4. TELIYA DHAL :2.5-3 KG/Q of castor oil.
- 12. STEP 7. Packing and Storage of grains • Machines used :pulse packing machine. • Materials used : pounches , gunny bags, polythene bags , jute bags etc. • Stored in godowns .
- 13. PULSE MILLING
- 14. METHODS OF MILLING Wet milling of pulses Wet method of pulse processing involves cleaning to remove dust, dirt, chaff, stone pieces, immature grains and other seeds. The easy to dehusk pulses are then soaked into water for a period of 2 - 8 hrs whereas difficult to dehusk type of pulses (pigeon pea, black gram, green gram) are often treated with red earth. The pulses are subsequently dried and then subjected to dehusking and splitting to obtain dal.
- 15. Dry method of pulse milling In case of dry method of pulse milling ,the pulses after cleaning are fed into roller dehusker where a scratch, dent and crack is formed on the outer seed coat. Pitted pulses are then stored for 2 to 3 days after applying oil on the surface. Generally 150 - 250 gm oil per 100 kg pulses is applied. The oil diffuses between husk and cotyledon and thus facilitates loosening of the husk. Water treatment (2.5 -3.5 kg water/100 kg pulses for overnight period) helps in further loosening of the husk. Then the pulses are subjected to drying and cooling. Now, the dried pulses are dehusked and splited to obtain dal.
- 16. Dehulling /Dehusking Process of Milling • Heat Conditioning Treatment: This process involves pitting of grain followed by high temperature short time heating of grain and holding the grain in conditioning bins for 6-8 hours. During this time it is believed that the grain sweats and it loosens the husk. The moisture of the grain is not adjusted for this preheating process. After conditioning, grain is subjected to dehusking. • Dehusking operation: After hydrothermal treatment, the pulse grain is subjected to mechanical treatment to remove the hull. Abrasive rollers either horizontal or vertical generally do this. The horizontal rollers are more common. The rollers are either coated with emery (stone particles coated on steel drum with cement) made of carborandum. The mechanism is mainly the tangential abrasion with abrasive surface and perforated sheet casing and rolling friction between grains to grain. The emery abrades the husk, which is further removed by grain-to-grain friction. The fan sucks off the fines generated during this operation. The mixture of husk, cotyledons and whole husked grain as well as unhusked grain are separated from each other by aspiration and grading and unhusked grain is subjected again to hydrothermal treatment.
- 17. • Splitting of dehusked grain: After dehusking, the whole dehusked grains called gota are obtained. This gota is further split into 2 halves. The splitting of gota is done either by under runner disc sheller or by gota splitter .A small degree of hydrothermal treatment is some times required to split the grain. This is done by applying water stray, followed by tempering and drying. After this process the splitting of grain into two halves is obtained by dal splitter.
- 18. Pigeonpea • Pigeon pea is widely grown by subsistence farmers in the warm semi-arid and sub-humid tropics. The pigeonpea is also known by several other names; tur, tuver, arhar, red gram, adhaki etc • It is often grown on poor soils and with few inputs. It is an important food in India and is popular in parts of East Africa and Central America and the Caribbean. Immature seeds and pods are used as a vegetable. • UP, MP, Maharashtra & Gujarat account for a major share in the production. It is cultivated both as a kharif(autumn ) and rabi(spring) crop. It is consumed in almost all the states in India.
- 19. Dry milling method of pigeon pea It is generally practiced in Madhya Pradesh and Uttar Pradesh. In this, the pulses are subjected to pitting in a roller and then oil treatment by applying 0.5-2.0 per cent linseed oil or any edible oil. Then the pulses are spread in the drying yard for sun drying for 2 – 4 days. The pulses are tempered by heaping and covering during the nights in between these days. After sun drying, again pulses are moistened uniformly with about 5 % water and kept as such on heaps overnight for moisture equilibrium. Then, these pulses are allowed to pass from the roller for splitting and dehusking. About, 50 % of the pulses are dehusked and split in first operation. After this, the husk are removed by aspiration and split dhal are separated from the mixture of husked and un- husked whole pulses. The mixture is once again moistened and dried in the sun and then dehusked and split. This process of alternate wetting and drying is repeated until almost all the remaining pulses are converted in to split dhal. The average yield of dhal ranges from 68-75 %.
- 20. Wet milling method of pigeon pea The grains are soaked in water for 3-5 hours in this method of milling. The soaked pulses are mixed with red earth at about 5 % thoroughly. The mixture is kept in heaps overnight. The whole mixture is then dried in the sun for 2-4 days until the husk of the grain are shriveled and loosened. The pulses are tempered overnight in between these days. By sieving, the red earth is separated from the pulses. The dried grains are dehusked and split in disc sheller. The dhal and other fractions are separated. In a single milling operation, about 95 % of the pulses are dehusked and split. The rest material again pretreated and milled to convert in to dhal. The red earth may facilitate in increasing the rate of drying and in loosening the husk. This method requires about 5 to 7 days for processing of a batch of pulses.
- 21. Other pre-milling treatments • Sodium bicarbonate treatment: Use of sodium bicarbonate, sodium carbonate,sodium hydroxide, acetic acid and ammonia as a replacement for vegetable oil in the traditional process reported a considerable improvement in dhal yield when sodium bicarbonate was used. • Sodium bicarbonate solution of 1 N was reported to be the most effective, resulting in dhal yield of 78% in addition to loosening of husk, it also reduced the cooking time of the resulting dhal. • Pigeon pea grain soaked in 6% sodium bicarbonate gave improved dehusking efficiency. They however observed an increasing loss of crude protein due to leaching as concentration of sodium bicarbonate solution was increased. A maximum hulling efficiency of 90.16% for grains treated with 10% NaHCO3 solution for 5 hours may be obtained. • Oil treatment: Entry of oil may displace the proteins from the surface of the bi-layer causing the loosening of the membrane. This will loosen the binding force between husk and cotyledons. Drying of oil water treated grain may cause the formation of a pore space below husk and cotyledons. During drying, water evaporates from the cotyledons.
- 22. Chick Pea • The oldest records of the cultivated chickpea are from Turkey and it is assumed that the crop spread out worldwide from that area. • It is the fifth most important legume in the world on the basis of total production. • India alone contributes over 75% of the total world chickpea production. The chickpea, also called by several other names, namely, Bengal gram, boot, chana, chola, chhole, and gram. Generally the crop is grown on small-scale farms both as a food and a cash crop. • The seeds are used whole, dehulled or as flour. Immature shoots and seed may be used as vegetables. • Gram is a rabi crop. The main producing states of gram are M.P., Rajasthan, UP and Maharashtra. Kingdom: Plantae Clade: Tracheophytes Clade: Angiosperms Clade: Eudicots Clade: Rosids Order: Fabales Family: Fabaceae Genus: Cicer Species: C. arietinum Tradeindia.com Researchgate.com
- 23. Chickpea Pre cleaning (Pre cleaner) Storage(Silos) Grading (Rotary cylindrical grader) Cleaning (Destoner) Pitting/scratching/scouring (Emery roller) Water mixing (4-5% moisture addition) Drying (Sun drying in open floor) Tempering/conditioning (Overnight/6-8 hours) Dehusking & splitting (Vertical stone grinder & emery roller Packing (50 kg gunny bag/50 kg polythene layer gunny bag) Broken grain Grading (Vibratory grader) Grading/colour sorting (Colour sorter) Cattle feed tradeindia.com
- 24. Green Gram Kingdom: Plantae Clade: Angiosperms Order: Fabales Family: Fabaceae Genus: Vigna Species: V. Radiata • Green gram or moong or munggo bean ranks third in production next to chickpeas and pigeonpea in our country. • Green gram is an excellent source of protein with higher digestibility of nutrients. • The production of moong is high in Maharashtra, AP, Orissa, Bihar and Rajasthan. The yield is more than 500 kg/ha in Punjab, Uttar Pradesh, Maharashtra and Bihar. Exportersindia.com
- 25. Raw Green gram Pitting/scoring (Emery roller) Cleaning (Destoner) Cleaning (Rotary cleaner) Tempering/conditioning (5-7 hours) Oil mixing (Warm conveyor (150 g/100 kg) Water mixing Tempering/conditioning (36 hours) Drying (Oil fired burner 70-80o C) (2-3 hours) Grading (Horizontal Vibratory Grader) Dehusking/splitting (Emery roller) (Horizontal +vertical) Tempering/conditioning (5-6 hours) Packing Amazon.com
- 26. Black gram Kingdom: Plantae Clade: Angiosperm Order: Fabales Family: Fabaceae Genus: Vigna Species:V. Mungo • Vigna mungo, the black gram, urad bean, ulundu paruppu, minapa pappu, mungo bean or black matpe bean (māṣa). • Black gram originated in South Asia, where it has been in cultivation from ancient times and is one of the most highly prized pulses of India. • Black gram is one of the important pulses grown in both Kharif and Rabi seasons. • The product sold as black lentil is usually the whole urad bean, whereas the split bean (the interior being white) is called white lentil. It should not be confused with the much smaller true black lentil (Lens culinaris). Amazon.com Agrifarming.in
- 27. Raw Black Gram Pre cleaning (Vibratory screen Drying Oil mixing Pitting/Scouring (Emery roller) Grading (Rotary cylindrical grader) Tempering/conditioning Dehusking/splitting (Emery roller) Grading Packaging Cleaning (Destoner) Polishing (Polisher) Grading (Vibratory Screen Amazon.com
- 28. Quality & Efficiency of process • In case of pulses best quality dal is produced when the milling efficiency is at it’s highest. • The scratching or abrasion of the cotyledon surface is not desirable in dal processing. Also broken corners during splitting of grain, as it sometimes happens in under runner disc sheller or plate mill, is also not desirable. Hence, the dal splitter is an additional machine used in the industry. • The optimum hydrothermal treatment is necessary to get good quality dal. • Excessive water treatment has been reported to induce cupping phenomenon in pulses, which lowers its quality drastically. The High Temperatures Short Time (HTST) treatment, if not done properly, has been reported to charred smell to dal. Hence, proper hydrothermal treatment as well as critical adjustments of machines is very important in getting good quality dal . • The size grading of the pulses is the most important operation in processing of pulses, especially in India. It is important due to large variations in the size of grains in commercial lots. Hence rotary graders are used which grade pulse in two sizes. Generally first size constitutes 80% of grain whereas second size gets 20% of grain. Though the dal obtained by both sizes could be of same grade, to get effectiveness of processing they are processed separately.
- 29. Effect of milling • Composition: Milling of the pulses influences the nutritional and functional properties of legumes. The seeds coat in the legume seeds accounts for 7 to 15% of whole seed,legume shows that the major portion of protein, fat, phosphorus and iron is present in cotyledons, whereas 80 to 93% of crude fiber and 32 to 50% of calcium content in food legumes. • Protein Digestibility: Dehulling improves the digestibility of legume proteins. Tannins present in seed coat form complexes with proteins and decrease their digestibility. Removal of seed coat decreases the tannin content significantly. Hence, improvement in protein digestibility due to dehulling is expected. • Functional Properties: Dehulling improves water and oil absorption foaming ability and emulsion activity of dry bean seed coat. Seed coat may have adverse effects. This may be due to probable interactions between seed coat materials and the endosperm protein components leading to decreased contribution of protein . • Cooking quality: Removal of the seed coat decreases the cooking time and facilitates improved palatability. • Complete removal of pesticide or fungicide content by cleaning, grading and processing .
- 30. REFERENCE • Rajesh Kumar Vishwakarma, Devi Mridula, Manikantan Ramarathinam, Pulse Milling Technologies, January 2005 • Er. om ,Dal Milling Process • https://vikaspedia.in/agriculture/post-harvest- technologies/technologies-for-agri-horti-crops/post-harvest- management-of-pulses/milling-of-pulses • Methods of Milling of Pulses,ECOURSES ONLINE