UNIT 4 RENDERING AND POULTRY BY-PRODUCTS Structure

4.0 Objectives 4.1 Introduction 4.2 Rendering 4.2.1 Preparation of Carcass Meal 4.2.2 Continuous Low Temperature Dry Rendering 4.2.3 Rendering of Animal Fat 4.3 By-products Available in Poultry Industry 4.3.1 Feather Processing 4.3.2 Processing of Hatchery Waste, Inedible Eggs and Egg Shells 4.4 Let Us Sum Up 4.5 Key Words 4.6 Some Usehl Books 4.7 Answers to Check Your Progress 4.0 OBJECTIVES After reading this unit, you will be able to: explain what is rendering; state different types of rendering employed for converting animal by-products into value added meals; justifL the importance of animal fat; narrate the steps for preparation of technical fat; describe different poultry by-products; and state the procedure of feather meal production. 4.1 INTRODUCTION The process of converting dead animals or condemned meat into value added products like carcass meal is referred as rendering. Actually rendering in earlier days was referred to the process of recovery of fat from dead animals, but now- a-days, the definition also covers the production of carcass meal, meat meal and technical fat. You will be studying about the preparation of bone meal and blood meal in the next unit. By-products of poultry industry include everything from poultry fmor processing plant that may not be directly used as human food. Some of these are hatchery waste, feathers, blood, egg shell, offal, fat and manure. This unit will also deal with these poultry by-products. Originally rendering means the recovery of fat fiom animal materid by heating but with the advancement in the by-product industry, it embraces all the process leading to the conversion of slaughterhouse by-products into animal feeds, fats and fertilizers. 4.2.1 Preparation of Carcass Meal For the preparation of meat cum bone meal or carcass meal, the process used is the thermal treatment i.e., rendering or sterilization. There are two types of technologies for utilization of carcass; they are dry rendering and wet rendering. Continuous low temperature dry rendering is used for producing better quality fats. In case of large animals like cattle, buffaloes, there is a significant value of dead animals for their hide, hooves and horns and subsequent products such as meat meal, bone meal and tallow. After separation of hide, horns and hooves, the remaining parts of thi: carcass should be conveniently discarded and sometimes could be further processed. The carcass rendering plant handles feedstock devoid of hide. horn, hoof and rurnen contents. The material contains protein, fat and water in different proportions and rendering is a process to recover proteins and fat while eliminating water. If rendering is not done, the material gets putrefied. The yield of the final product meat meal, bone meal and tallow depends largely on the weight and level of nutrition of the animal. A) Wet rendering The wet rendering method involves the use of pressure batch cookers in which the pre-cut raw material is injected with live steam to a temperature of 140°C under pressure for 3-4 hours. After this time, the pressure is slowly reduced and the fat run out into a receiver and further purified by gravity or centrifugation to settle out the water and fines. The proteinaceous solids or greaves are emptied from the cooker, and the fat removed by pressure and solvent extraction. They are ;hen gro~dand dried. Bone meal preparation primarily involves the wet rendering process. B) Dry rendering The dry rendering process uses heat in the form of steam and water over a period of 1-2 hour at atmospheric pressure to drive out water indirectly fiom the fat in the cooker without loss of nutrients. Here no steam or hot water is allowed to pass into the cooking vessel, but the steam is allowed into the outer jacket only. Dry rendering yields 20 per cent more than the wet rendering process. Pre rendering operations: Raw materials originating on the killing floor should be processed with emphasis on speed and thorough cleaning, so that the end product of maximum value inay be obtained. The raw materials should be prepared properly before placing it into the cooker. Head, feet, condemned carcasses from the killing floor and bones from the boning department are reduced or crushed to small pieces by shredders. Bones also can be reduced in size in machines called "pre breakers". Intestines and other soft tissue coming fiom the killing floor are dirty with full of feed or manure and therefore must be opened and cleaned as well as reduced in size before charging into the cookers in inedible rendering. Table 4.1: Comparisons between Dry Rendering and Wet Rendering Rendering and Poultry - -- By-products Wet Rendering Dry Rendering I

In wet rendering the material In dry rendering the material is is cooked in added water. cooked in its own water. Temperature applied is about 110 OC Temperature applied is about 130°C and pressure of 40 psi, for 60 minutes and pressure of 60 - 80 psi, for followed by drying for about 3-4 hours 3 - 4 hours. Better sterilization of ---lmaterial at higher Temperature. The cooker is of vertical type. The cooker is of horizontal type. The recovery of fat is better than dry The recovery of fat is not better than rendering. To produce good grade wet rendering. Tallow is dark tallow, viscera must be cut and coloured. More tallow is lost in dry washed. rendered meat. I Yield of carcass meal is less than dry Yield of carcass meal is more than rendering as 25 per cent of meat is wet rendering. lost in the gravy. Flow chart for dry rendering Carcass received -1 Removal of hide, horn and hoof, evisceration and removal of stomach and intestinal contents -1 Carcass divided into pieces (manually) -1 Reduce the size of the pieces to about 60 rnrn (mechanically) -1 Loading such pieces into dry renderer -1 Cooking at 60- 80 psi for 3 - 4 hours -1 Cooked material emptied into percolating tank

-1 -1 Centrifuged Fat removed -1 -1 Fat settling tank Wet material pressed and moisture reduced and -1 then dry material is pulverized (powdered) -1 Technical fat Meat cum bone meal By-products Processing Table 4.2: Composition of Meat cum Bone Meal Plant Constituents Percentage (per cent)

Crude Protein Min. 55

Crude Fat Max. 7

Calcium Min. 10

Phosphorous Min.5.O

Clostridium spores, salmonella and E. coli Nil

Moisture Max. 7

Pepsin digestibility 85

Some basic information on stock feed: Knowledge of composition of raw material is required to calculate the yield of meals to be expected from different offals. Meats may vary greatly in their composition depending upon the animals and also hmdifferent parts of the anjmals from which they are derived. Irrespective of the type of raw material used, the aim is to obtain a final product with an approximate composition of 85 per cent protein and minerals, 7 per cent fat and 7 per cent moisture. Any excess of moisture or fat leads to reduction in keeping quality and is undesirable. As stock feed is not made from one type of raw material, the proportion of each ingredient will influence the final yield. If only lungs, tripe, intestines containing very high percentake of water are used, a much smaller yield will be obtained. A commercial meal can only be prepared without removing fat when original fat level in the raw material do not exceed three and half per cent though we usually get higher percentages (more than 7 per cent) of fat in raw materials. Hence, to maintain the desired fat percentage, expulsion of fat is required. Besides, the inherent characters of the raw materials, the yield of the final product depends upon the following factors. They are as follows:

a Type of rendering method used i.e., wet rendering (soluble and suspended materials is lost) or dry rendering (all the components are fully salvaged).

Speed of processing.

a Type of equipments used. Experience and skill of the operators, which contribute to the gain or loss in the final yield. In general, the conversion ratio of raw materials to dry meal is:

a 3 : 1 in dry rendering process

4 : 1 in wet rendering process

a 5 : 1 in blood meal preparation 20 ! I Commercial terms used for various products Rendering and Poultry By-products i Commercial markets accept a definite terminology for animal by-products. They include: I

I i) Raw bone meal: Raw bone meal is a misleading term and is defined as the meal prepared from bones which have been cooked in open kettle without steam pressure and are therefore, sterilized and safe for use. The protein content is usually high, not less than 23 per cent (only a small quantity of ossein is removed). Average composition: Protein - 26 per cent Calcium - 23 per cent I Phosphorus - 11 per cent Fat - Acceptable level of fat. ii) Steamed bone meal: Bone meal prepared by applying steam pressure either by dry rendering process or wet rendering process. Steam removes much of the proteins and fat. Average composition: Protein 7 per cent Calcium - 32.5 per cent Phosphorus - 15 per cent iii) Bone ash: Bone ash is the ash obtained by burning the bones in open air with free access to air and contains 15.3 to 16.6 per cent phosphorus. iv) Meat meaVDigester tankagemeat scrape/Dry rendered tankage: It is the product obtained by wet or dry rendering of animal tissue and should contain not more than 10 per cent phosphoric acid i.e., 4.4 per cent phosphorus and not less than 55 per cent protein. Hooves, horns, hair, blood, manure and stomach and intestines are not included as raw material.

v) Meat and bone scrape, Meat and bone meal or Carcass meal: These are the terms used to describe a product whose protein content is less than 55 per cent and phosphorus content is higher than 4.5 per cent. Bones comprises of much of the proportion of the raw material for this product. vi) Blood meal: Unlike other products, blood meal has very high protein content, over 80 per cent and low in calcium and phosphorus. Good quality blood meal should have 85 per cent proteins and free from fat, fiber and phosphate of lime. vii) Liver meal: Liver meal is the product obtained by drying and grinding livers from slaughtered animals. Condemned livers are used mostly for the purpose of liver meal preparation. Liver meal should contain at least 27 mg of riboflavin/ pound. Market price of the above products except bone meal is determined by their protein content. They are priced on the basis of "Protein units'' (each per cent of protein present in a ton of meal). The price of bone meal is controlled by the amount of phosphorus present. By-products Processing 4.2.2 Continuous Low Temperature Dry Rendering Plant Continuous low temperature dry rendering is used for production of better quality fats. This system uses heating, separation and cooling on a continuous basis, and is usually regarded as the ideal process. The process involves following steps: Mincing of raw material. Melting by live steam injection at 90 C. Continuous separation of solids from the liquid fat in a decanter centrifuge. Further heating.

Cooling in a plate heat exchanger below solidification point. A prime consideration in the rendering of fat is the prevention of the breakdown of fat into fatty acids and glycerides by the action of the enzyme lipase, which is active at 40-60°C. Above 60°C lipase is inactivated. The continuous low temperature system utilizes this action and at the same time minimizes undesirable chemical activity, burning, oxidation and off flavours. This process requires less floor area and labour than dry batch rendering. The disadvantage of continuous low temperature dry rendering is that hair and wool cannot be hydrolyzed by this process as sterilization by pressure cooking is not done. 4.2.3 Rendering of Animal Fat Fats are one of the major components of animal carcasses and its quantum is associated with the water content of the carcass. Fat accounts for 18 -30 per cent of the carcass weight of market steers and 12- 20 per cent of the live weight of average market hog. Fats are obtained from food animals and fowls after they are slaughtered. They are both edible and inedible in nature. Greater quantities are provided by beef and pork and a lesser quantity comes from sheep and goat. The fats are mainly grouped into: Killing fats which are stripped off from animals at the time of slaughter. Cuttingfats that is trimmed off from the carcasses when they are taken out hmchiller. Killing fats and cutting fats may be used for the preparation of lard and tallow for edible purposes. Inedible fats are recovered fiom dead and diseased animals and fiom non prime parts of the carcasses. In most cases fatty tissue are codked or exposed to low temperature and thus fat is released primarily through physical rupture of the fat cells. Steam rendering process: The steam rendering process is the most common process in which fat tissue is charged into large tank having conical shaped bottom. Live steam is injected and rendering is done under pressure to hasten up the time of cooking. After complete processing, the pressure is slowly released and the mass is allowed to settle before drawing off the adhered water. Dry rendering of fat: Almost all the inedible tallow and grease are produced by Rendering and Poultry By-products dry rendering process. In this process, fatty tissue is fed to a horizontal steam jacketed cylinder which has a set of internal blades rofBi-&macentral axis and nearly touching the wa;:s. Then the fat is cooked under elevated pressure, I atmosnheric Dressure or under vacuum. The cooked out material is dumped into a strainer to remove cracklings. The fat thus separated and collected is used as technical fat. The other methods most commonly used as alternative to the dry rendering process are, open kettle, drip, and caustic rendering process. I Tallow or lard: Tallow is referred to as the rendered fat of cattle and sheep 1 whereas lard is he fat from pig. Otherwise the animal fat which has a titre of greater than 40°C is known as tallow and fat with a lesser titre is called lard. Titre is the temperature at which fat solidifies. It refers to the softness or hardness of i tallow. Inedible tallow and grease are used in livestock or poultry feed as high 1 energy additive. They also reduce the dust, improve colour and texture. Enhance I I palatability of animal feed. Fatty acids from tallow are also used in industrial I chemicals like abrasive, lubricants, shaving cream, candles, cement additives, 1 cleaners, cosmetics, paints, polishes, detergents, soap, plastics, printing inks, i perfiunes etc. Edible tallow and lard are used in oleomargarine and cooking fats. I You have already studied about different rendering methods, rendered products and use of rendered materials briefly in Unit-1 1 of Course BPVI-022.

- - Check Your Progress 1

1) Compare dry and wet rendering process.

...... 2) What is continuous dry rendering process?

...... 3) Give the flow diagram of meat-cum-bone meal preparation...... By-products Processing Plant

By-product Application

Feather Livestock feed, as bedding, fertilizer, ornamental use and in sports. Blood Livestock feed, as fertilizer, fish bait.

Offal Livestock feed, pet food, fish food. ----I------I------Rendering and Poultry By-product Application By-products Mixed poultry by-products meal Poultry feed (At 5-7 per cent level) 1 Hatchery waste Poultry feed (At 3 per cent level) Yield 25 per cent Protein 35 per cent Fat 40 per cent Calcium 0.05 per cent Phosphorus 1 per cent

Poultry manure Fertilizer Moisture 15-1 8 per cent In poultry feed e.g. layer ration (Up to 15%) Protein 25-30 per cent Uric acid 6-8 per cent Ash 15-25 per cent Calcium 3-6 per cent Phosphorus 1.5-2 per cent 4.3.1 Feather Processing Feather constitutes about 7 per cent of body weight of poultry. Feather can be utilized for clothing, insulation, bedding, decoration, sports items, feather meal and fertilizer. Feather characteristics vary according to the species of bird, age, sex and location on the body. They are often classified in the different groups like hard feathers, saddle feathers, half flue quarter fluff fluff,plumules and down. Downs are insulating undercoat of lightweight feathers without a shaft or stiff quill and with a long iiber length. The down is 12- 15 per cent of the total weight, and feathers account for the 85-87 per cent of the remaining weight. When feathers are saved, the more important feathers of the wing and tail are removed after slaughter and before scalding, but this is not done in commercial operations. When feathers are saved, they may be held for as long as 12 hours, if soaked in a solution containing salt (NaCl), hydrochloric acid and water. The feathers are usually washed, often 5-8 times with mild soap or cleaning agents (to protect the essential feather oils) to remove dirt and blood, and this washing should leave the feathers and down at a neutral pH. Often, the dust and dirt are . filtered out up to 15 times. If the feathers are not properly cleaned, they may mildew or deteriorate, reducing their insulating and durability properties. A bleaching agent, such as potassium permanganate, hydrogen peroxide, or chlorine can also bc utilized. Finally, the feathers are tl~oroughlyrinsed in clean water, blow or steam dried to encourage fluffing, and then down, feathers, and big feathers are sorted by air currents into groups by size (weight and lengh). The use of feathers in bedding has declined because of the developmeilt of synthetic fibers and plastic foam, but good-quality bedding still uses body feathers, generally from waterfowl. Basic requirements for good bedding feathers are maximum volume when in use and minimum volunle for storage. Color, shape, size and plumage patterns are important when feathers are used for decorative purposes. For this reason, cock pheasants are in demand because of By-products Processing their brightly coloured feathers. In many cases, the feathers are dyed, bent and Plant trimmed to desired patterns. For sporting equipment, feathers are carerlly hand-selected. For example, sturdy feathers from mature turkeys are used for fetching arrows. Feathers on an individual arrow must dlcome from either the right or left wing to ensure proper rotation of the arrow. Stiff feathers are also used for shuttlecocks used in badminton. Other selected feathers are used to manufacture artificial lures for fishing. Amongst all above stated uses, feather meal has the largest market. Feathers are composed of a complex protein - keratin, which must be broken down by hydrolysis during rendering to make them more digestible when used in animal feed. Flow &art for preparation of feather meal Collection of feathers &om poultry processing plant .1 Washing with mild soap and water 3. Draining and pressing -1 Wet rendering at 30-45 psi for one hour .1 Cooling and fat removing .1 Drymg and pulverizing -1 Packing in bags

Tabie 4.4: Per cent Yield rand Csnapsitiion of Poultry By-pt.eduets Meal Constituent Feather Blood Offal Mixed By- Meal Meal Meal Products Meal Wd 33 18 55 33 Moistwe 7 9 10 8

Crude fat 3 1 24 18

-- Feather meal is rich in cystine, tlnrxrnine and arginine but deficient in four essential amino acids such as lysine, metheonine, histidine, and tryptophan. Therefore, when feather me@ is to be added in feed of monogastric animals like poultry and swine, the above mentioned essential amino acids should be added in feed. -

The practical level of use of feather meal in animal diets is 0.5 -1.5 per cent. Rendering and Poultry Feather meal is utilized better by the ruminant animals like cattle, sheep and goats. By-products The digestibility of feather meal is dlrectly affected by cooking time and pressure (amount of hydrolysis), usually with more intensive processing resulting in higher availability of amino acids and higher biological values. Mixed poultry by-product meal is a mixture of blood, offal and feathers, in natural proportions that have been rendered and dried. Sometimes excess fat is removed. Offals excluding feathers are cooked at pressure for half an hour and then allowed to dry and cool before fat extraction and grinding and packing is done. Feathers are first hydrolysed and then added to offals. 4.3.2 Processing of Hatchery Waste, Inedible Eggs and Egg Shells Hatchery waste Hatchery waste consists of infertile eggs, dead embryos, dead chickens, or pouIts and shells of hatched eggs. Waste from hatcheries that produce egg laying chickens sometimes also contains male chicks that are destroyed at the time of sexing. The contents of the eggs are collected and cooked at 1Opb pressure for 15 minutes and then dried. Average yield of the dried hatchery by-product meal is 25 per cent. When the whole eggs with shell are processed, the disadvantages are the ratio of calcium to other ingredients is high and the hard gritty texture of the shell makes whole eggs unpalatable. Inedibte eggs lnedible eggs are eggs with black rot, white rot, sour eggs, moldy eggs, musty eggs, decomposed eggs, putrid eggs, smashed, broken, denatured eggs etc. These inedible eggs are first cooked, then dried and grounded. Inedible eggs are often used as pig feed. Because shells constitute 10 per cent of the eggs, the whole egg often contains too large a prop~rtionof calcium for balanced pig ration.

Egg shells represent approximately 11 per cent of the total weight of an egg and are available in large quantities from egg breaking plants and commercial hatcheries. After collection, egg shells are dried and heated at 80°C until they are sterilized. Then they are ground into small particles to produce egg shell meal.

Check Your Progress 2 1) List the poultry by-products...... 2) Write the uses of feathers...... By-products Processing 3) Give the flow diagram of feather meal preparation. Plant

4.4 LET US SUM UP - - In this unit, we have learnt about the rendering process and different poultry by- products. Previously the word 'rendering' was used to denote the process of recovery of fat from animal material by heating. Now-a-day rendering means the process of converting dead animals or condemned meat into value added products like carcass meal, bone meal, technical fat etc. It is mainly of two types namely, dry rendering and wet rendering. Different terms are used in the market for rendered materials like, raw bone meal, steamed bone meal, meat meal, meat and bone meal or carcass meal, blood meal, liver meal etc. You have also studied about the killing fats and cutting fats; tallow and lard; and the steam and dry rendering process for the recovery animal fat. Various poultry by-products are dealt in this unit. These are available from poultry processing plant, hatchery, egg processing plant and poultry fms.By-products fiom poultry processing plant are feathers, blood, offal (head, feet, inedible viscera like intestine, lung, pancreas, spleen etc.). Infertile eggs, dead embryos, egg shell, un-hatched chicks, un-usable chicks etc., are obtained fiom hatchery; unsound eggs and egg shell from egg processing plant and poultry manure comes from poultry farm, Feathers are utilized for feather meal preparation, for clothing, ins,ulation material, bedding and sports items. 4.5 KEYWORDS ------Monogastric Animals The animal having single stomach. E.g. pig. Crackling The final product obtained after completion of dry rendering process. Glue Inferior quality gelatin. Lanolin Wool fat. Poult A young fowl, especially a turkey, chicken, or pheasant. Rendering Preparation of meal by removing unwanted moisture by using thermal processing. Steer A male bovine animal and especially a domestic ox castrated before sexual maturity. Stick Water Molasses like product remaining at last during production of condensed meal. This is avery high source of nitrogen and used for irrigation of gardens. Tankage Digested material in dry rendering. Technical Fat Inedible fatlgrease obtained in the process of making meat meal or meat cum bone meal. Rendering and Poultr) 4.6 SOME USEWUL BOOKS By-products Hui Y.H., Nip Wai-Kit, Rogers R. W. and Young O.A. (Editors). (2001). Meat Science and Applications. Marcel Dekker, INC., New York. Mann. I. Processing and Utilization ofAnimal By-products. FA0 agricultural Development Paper no. 75. FAO, UN. Ockerman H. W. and Hansen C.L. (2000). Animal By-productsprocessing and Utilization. Lancaster, PA: Technomic.

4.7 ANSWERS TO CHECK YOUR PROGRESS - -- Check Your Progress 1 1) Dry and wet rendering processes are compared below:

followed by drying for about

rendering. To produce good grade wet rendering. Tallow is dark viscera tallow, must be cut and washed. coloured. More tallow is lost in dry

2) Continuous low temperature dry rendering uses heating, separation and cooling on a continuous basis, and is usually regarded as the ideal process. It is used for production of better quality fats. The process involves following steps: a Mincing of raw material.

a Melting by live steam injection at 90 O C.

a Continuous stpiration of solids from the liquid fat in a decanter centrifuge. Further heating. Centrifugation.

a Cooling in a plate heat exchanger below solidification point.

3) The flow diagram of meat cum bone meal preparation is as follows: By-products Processing Carcass received Plant L Removal of hide, horn and hoof, evisceration and removal of stomach and intestinal congnts L Carcass divided into pieces (manually) L Reduce the size of the pieces to about 60 mm (mechanically)

Loading such pieces into dry renderer .1 Cooking at 60- 80 psi for 3 - 4 hours L Cooked material emptied into percolating tank

Cracklings Fat L L Centrifuged Fat removed L L Fat settling tank Wet material pressed and moisture L reduced and then dry material is Technical fat pulverized ( powdered) 3. Meat cum bone meal

4) Different terminology used for meals prepared fiom nleat plant by-products are as follows: Raw bonemeal Steamed bone meal Meat meal Meat and bone meal or Carcass meal Bloodmeal Livermeal Check Your Progress 2 1) Poultry by-products are listed below: i) Poultry dressing plant waste: Feathers Blood - Head Rendering and Poultry By-produck - Feet - Inedible viscera (Intestine, lung, pancreas spleen etc.) 3 Hatchery waste: infertile eggs, dead in germs, dead embryos, egg shell, un-hatched chicks, un-usable chicks etc. 3 Egg processing plant waste: unsound eggs and egg shell. iv) Poultry manure: used up litter and wet droppings from cage houses. v) Dead birds 2) Feathers can be utilized for the following purposes: a Clothing material, Insulation material, Bedding material,

a Decoration, a Sports items, Feather meal, and Fertilizer

3) Flow diagram for preparation of feather meal is given below: Collection of feathers from poultry processing plant 4 Washing with mild soap and water .1 Draining and pressing 3. Wet rendering at 30-45 psi for one hour .1 Cooling and fat removing

J. Drying and pulverizing .1 Packing in bags