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1 Industrial Food Processing Wastes INTRODUCTION As a result of changing waste-handling technology, many industrial food processing wastes now being fed to animals were once considered to be without economic value as animal feed. Other factors that have increased the interest in wastes as animal feeds include the cost of disposing of waste and increased restrictions, brought about by environmental con- cerns, on disposing of waste materials. The necessity of separating solid waste from liquid waste, as well as the necessity of removing suspended and dissolved substances from wastewater before discharging it, has re- sulted in the production of waste materials that are lower in water content and consequently more economically attractive as animal feeds. More stringent controls on the use of pesticides have also reduced the pesticide levels in food processing wastes. QUANTITY In general, information on quantities of industrial food processing wastes (residuals) is limited. Information on processing wastes from fruit, ve*~- etable, and seafood processing, collected by Katsuyama et al. (1973), is presented in Tables 1 and 2. Although these data are not current, an overall view is given of waste from fruit, vegetable, and seafood processing. The major changes since 1973 would be greater utilization of wastes for animal feed and as sources of energy. There are also data on quantities of waste in the sections on specific wastes. Table 1 summarizes food processing s

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6 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS TABLE 1 Yearly Food Processing Industry Solid Residuals, by Product and Disposal Method TotalTotal Total TotalTotalNot Raw Tonsas in By-Resid-Accounted ProductProcessedSolids LiquidFeed OtherProductsualsFor Vegetables Asparagus10922 017 17383 Bean, dry2095 a2 26(-1) Bean, lima1099 09 917(-3) Bean, snap57161 358 581180 Beet24559 516 168219 Broccoli sprouts, cauliflower23619 182 82100a Cabbage20958 55 569( -1 ) Carrot25433 291 a911279 Corn2,24981 31,388 1,3881,46938 Greens, spinach2187 a22 22304 Mushroom6129 a 029( - 2) Pea52622 044 a44674 Pickle50836 1 037(-14) Potato, white3,23877 44943 9431,061154 Pumpkin, squash20020 822 2235088 Tomato6,322345 27109 109472136 Vegetable, misc.1,106100 47100 100245a Fruits Apple95282 a100 7918126327 Apricot1095 a6 28144 Berry1819 21 1132 Cherry17218 14 a4241 Citrus7,07572 12,721 32,7212,794281 Fruit, misc.13623 a7 29333 Olive772 a 9910a Peach998163 1345 4085263(-17) Pear37265 933 3310913 Pineapple81627 9326 3263630 Plum, prune245 1a 061 Specialtiesb2,26839 22190 152092720 Seafood Clam, scallop8211 a 01 259 Oyster180 2 141416a Crab274 14 0201 Shrimp1096 3714 a156018 Salmon1090 324 25363 Sardine240 0 555a Tuna, misc. seafood4720 a62 27909082 U.S. total30,3911,514 2896,421 1196,6248,420950 NOTE: All figures x 1,000 metric tons; rounded (after adding). a4S0 metric tons or less. bBaby food, soups, ethnic foods, health food, and prepared dinners. SOURCE: Adapted from Katsuyama et al. (1973).

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industrial Food Processing Wastes 7 industry solid residuals by product and disposal method. The weight not accounted for, when it is a positive number, represents materials probably leached into wastewater and other product shrinkage in the time between weighing the raw product and processing it. When the numbers are neg- ative, the weight not accounted for is probably due to errors in estimating the percentage yields of the residual tons disposed of. Table 2 shows the same data as Table 1, but on a regional basis. PHYSICAL PROPERTIES In general, food processing wastes contain a high percentage of water, are perishable, and must be processed rapidly. The dry matter of animal processing wastes tends to be high-protein, low-carbohydrate materials that are available throughout the year. The dry matter of fruit and vegetable processing wastes tends to be low-protein, high-carbohydrate materials that are seasonably available. FRUIT AND NUT PROCESSING WASTES Apple (Malus pumila) Processing Wastes Several wastes Tom apple processing are suitable animal feeds. Apple pomace, the residual material from pressing apples for juice, contains TABLE 2 Region Food Processing Industry Solid Residuals per Year, by TotalTotal Total Total Total Not Raw Tonsas in By- Resid- Accounted Region Processed Solid Liquid Feed Other Products ualsFor New England 889 8 23104 14118154 163 Mid-Atlantic 1,868 254 699 59154417 118 South Atlantic 7,546 200 622,436 132,4492,712 299 North Central 5,342 363 251,156 181,1791,560 56 South Central 1,106 49 23195 6200272 39 Mountain 218 18 342 4262 12 Northwest 3,909 136 521,263 121,2791,460 100 Alaska 145 0 453 4652 5 Southwest 9,351 499 551,186 751,2611,824 118 U.S. Total 30,374 1,527 2946,484 2016,6888,513 910 NOTE: All figures x 1,000 metric tons; rounded (after adding). SOURCE: Adapted from Katsuyama et al. (1973).

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8 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS pulp, peels, and cores. Between 250 and 350 kg wet pomace are formed from each ton of apples pressed for juice, or 25 to 35 percent of the fresh weight of the apple is retained in the pomace after pressing (Smock and Neubert, 19501. The residual material from canning, drying, and freezing, also called apple pomace, consists of the peels, cores, and discarded apples or pieces. Either type of apple pomace may be used for vinegar or other by-product production. Pomace is also used for livestock feed (Katsuyama et al., 19731. Leaves, stems, dirt, and some other wastes are disposed of as landfill or by field spreading. Apple pectin pulp is the residue following extraction of pectin from apple pomace. Pectin extraction is less commonly practiced than in the past because citrus pectin extraction is more com- petitive (Ben-Gee and Kramer, 1969~. Apple pomace from juice pressing often contains 0.5 to 1.0 percent rice hulls that are added to aid filtration (Walter et al., 19751. Dried rice hulls were added at a ratio of 1:13 on a dry-weight basis in one study (Wilson, 19711. Other filter aids include diatomaceous earth and fiber paper (Katsuyama et al., 19731. Nutritional Value Apple pomace and pectin pulp, wet, dried, or ensiled, are suitable feeds for ruminant animals (Smock and Neubert, 19501. Apple pomace is pal- atable to cattle and sheep; pectin pulp is less palatable to dairy cows than is apple pomace, and addition of molasses was suggested to increase the palatability of pectin pulps. Smock and Neubert (19503 reported that apple pomace was unsuitable for horses and of questionable value to pigs. Average digestion coefficients of wet apple pomace for ruminants are protein, 37 percent; fat, 46 percent; fiber, 65 percent; and NFE, 85 percent. Burris and Priode (1957) found apple pomace had feeding value similar to grass silage for wintering beef cattle. Addition of rice hulls increases the fiber content and lowers the feeding value of pomace. Processing Fresh pomace spoils rapidly and must be used quickly or be preserved by dehydration or ensiling. Drying to about 10 percent moisture prevents spoilage and spontaneous combustion. Drying takes place in direct-fired, rotary-drum driers, and the pomace is then ground in hammer mills (Cruess, 19581. The processing may result in some heat damage to the protein. Apple pomace is often mixed with alfalfa or corn for ensiling (Smock and Neubert, 1950~. Cull apples may also be preserved as silage by mixing

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Industrial Food Processing Wastes 9 with 20 percent alfalfa hay. Apples ensiled alone result in a very high moisture product with considerable loss by drainage. Citrus Processing Wastes Wastes from the citrus industry are very well utilized as by-products, including as feed. Approximately 39 percent of the processed fruit is not used in the primary product; 97 percent of this amount is recovered as by-products (Jones, 19731. Wastewater treatment accounts for the major remaining waste problem in the citrus industry. Recent developments have centered on the use of activated sludge wastes as animal feed and are reviewed in the section, "Citrus Activated Sludge." Hendrickson and Kesterson (1965) reviewed the processing of citrus wastes, the composition of by-products, and their utilization. The three main by-product feeds from citrus processing are 1. Dried citrus pulp, which is formed by shedding, liming, pressing, and drying the peel, pulp, and seed residues to 8 percent moisture. 2. Citrus meal and fines, which are formed and separated during the drying process. A typical processing plant produces 85 percent citrus pulp, 14 percent citrus meal, and l percent fines. Citrus meal has higher density than pulp, and higher fiber, nitrogen-free extract, and ash content. 3. Citrus molasses, which is made by concentrating the press liquor from the citrus peel residue. It is usually added to the dried citrus pulp. Most of these materials are utilized as animal feed, although citrus peel liquor and citrus activated sludge are utilized to a lesser extent. Citrus peel liquor is a by-product, similar to citrus molasses, but not as concen- trated (S. Reeder, SunKist Growers, Inc., Ontario, Calif., 1979, personal communication). The citrus peel liquor studied by Lofgreen and Prokop (1979) had a dry matter content of 47.3 percent. In feeding trials with growing beef cattle, citrus peel liquor was found to have a net energy for maintenance (NEm) of 2.24 Mcal/kg and for gain (NEg) 1.48 Mcal/kg on a dry-matter basis (Lofgreen and Prokop, 19791. Citrus peel liquor fed with cane molasses contained higher net energy values than either one alone. NEm and NEg are 1.97 and 1.32 Mcal/kg, respectively, for citrus molasses' on a dry-matter basis (National Research Council, 19761. Citrus activated sludge is produced by treating the liquid wastes from citrus processing plants. Sludge recovery and the nutritional value for poultry have been studied (Damron et al., 1974; Jones et al., 19751. Dehydrated sludge was found to be profitable. Dried sludge was acceptable as a poultry feed for up to 7.5 percent of the diet (Damron et al., 19741. Its inclusion in the diet reduced the amounts of yellow corn, soybean

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1O UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS meal, and phosphorus required. However, amounts of fat and methionine had to be increased to maintain energy and sulfur amino acid levels, respectively. The dried sludge also improved skin and egg yolk color, and no off flavors were detected in egg yolks or albumin. Higher levels of dried sludge in the diet had detrimental effects. Peach (Prunus persica) Processing Wastes Peaches are graded and the percent of cull fruit determined before shipment of the entire lot from orchard to processors. Batches of cull fruit may need to be sorted in order to be accepted, or the grower may choose to dump the fruit in the orchard to avoid sorting costs. At the processing plant, cull and undersized fruit are removed. The total peach processing residual is 26 percent of raw fruit. The disposal methods used are land disposal, 63 percent; liquid waste, 5 per- cent; feed, 17 percent; and other by-products, 15 percent (Katsuyama et al., 1973~. Usually peeling is done by the use of lye solution and washing. Dry caustic (lye) peeling methods have been investigated but are less commonly used. The waste from lye peeling is either soluble or in very fine particles and is highly alkaline. Dry caustic peeling waste sludge has the following properties: 9 to 10 percent solids content, pH of 13 to 14, dark brown color, and applesauce-like texture (Smith, 19761. Culls and pieces are removed at various stages of the processing operation. Dry wastes, in- cluding trash and cull fruit, are usually used for landfill or soil application; some fruit is used as feed or for alcohol production. Screened solids are removed from the wastewater and disposed of as above (Katsuyama et al., 19731. Peach peeling slurry from wet-peel methods may be recovered from the wastewater by shaker screen sedimentation treatment, or it may be discharged into the wastewater stream. Dry peeling wastes are kept out of the waste stream (Gray and Hart, 19721. The factors that hinder the use of peach wastes as animal feed include (1) costs of transportation of the high-moisture wastes from processing plants to livestock producing areas; (2) the high sugar content of peaches, which makes drying difficult (and a suitable drying technology has not been developed); and (3) the short canning season. Little information is available on the feed value of c peach wastes. Pear (Pyrus commur~is) Processing Wastes In the past, pear waste was processed into two feed products, pear pulp (or pomace) and pear molasses. This is no longer done on a commercial

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Industrial Food Processing Wastes 11 scale. The 1979 production of pears in the United States was 781,553 metric tons with 502,680 metric tons or 64 percent processed (U.S. De- partment of Agriculture, 19801. According to Katsuyama et al. (1973) about 29 percent of the raw pear tonnage was residual and 30 percent of the residual was recovered as feed. In 1950, when pear waste processing was being developed, 40 percent of the raw tonnage was residual (Graham et al., 19521. From one ton of waste, 55 kg of pear pulp (8 percent moisture) and 135 kg of molasses (50 percent sugar content) can be obtained (Brown et al., 19501. Pears are peeled both mechanically and chemically (lye peeling), but mechanical peeling predominates. Present methods of disposing of pear wastes include landfill and field spreading, with some of the solid wastes (peels, cores, and screened solids) being used as feed. Because of high transportation costs these wastes are fed fresh by local farmers (G. York, University of California, Davis, 1979, personal communication). Other methods of waste recovery have been considered and some implemented. These include fermentation to produce alcohol, methane production, and edible juice recovery. Nutritional Value According to Guilbert and Weir (1951), pear pulp and pear molasses are both very palatable to ruminants. The pear pulp studied contained a small amount of other fruit wastes. In feeding trials, steers were fed a fattening diet with pear pulp forming 25 percent of the concentrate, replacing mo- lasses and dried beet pulp. Pear pulp had a value of 70 to 75 percent of molasses and dried beet pulp, and pear molasses had a value of 115 to 120 percent of cane molasses. Pear molasses had a lower nitrogen and ash content and higher total digestible nutrients than cane molasses. Pear molasses was more palatable than beet molasses-so palatable that it could not be fed as free choice but instead had to be mixed with other feeds. Feeding trials with sheep were also conducted (Guilbert and Weir, 19511. The total digestible nutrients, dry-matter basis, for pear pulp and pear molasses were 60 and 86 percent, respectively. Processing According to Brown et al. (1950) pear wastes processed for feed and containing some other wastes had an average solids content of 13.8 per- cent. The wastes included variable quantities of peach, tomato, and grape wastes. The variability of the composition of the waste made processing more difficult. Pear waste could not be dehydrated directly and the slimy

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12 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS character of the waste made pressing difficult. To overcome these prob- lems, a process was developed, and later used commercially, consisting of grinding the waste in a hammer mill, liming, aging for a short time, and pressing. The press juice was concentrated to form molasses and the press cake shredded to form pear pulp. Because of the low fiber content of the waste, a certain amount of dried pulp or other material was added to aid pressing. Fruit Canneries' Activated Sludge In several food processing industries, wastewater is treated by activated sludge methods, and the feeding value of some form of activated sludge was studied. Since many fruit and vegetable processors process several fruits or vegetables at one plant and could use activated sludge treatment, this topic is covered separately. Waste activated sludge treatment was evaluated at a plant processing apples, pears, peaches, plums, crabapples, and cherries (Esvett, 19761. The principal costs of the system were for additions of nitrogen and phosphorus because the wastes were low in these, and energy costs for aeration, sludge circulation, and sludge disposal. Sludge at the plant is currently thickened and disposed of by application to agricultural land. Physical Characteristics The sludge is highly viscous and can be moved by a bucket-type loader or belt conveyor (Esvett, 19761. When the sludge was stored for 10 months in a 208-liter drum, deterioration and production of ammonia were evident. Nutritional Value The composition of the sludge, dry-matter basis, was 39.1 percent crude protein, 3.2 percent crude fiber, 0.8 percent ether extract, 11.64 percent ash, 1.08 percent calcium, and 1.28 percent phosphorus (Esvett, 19761. In a digestibility study, biological solids (or concentrated activated sludge) were fed to steers as 2.3, 4.5, and 9.2 percent of the diet, on a dry-matter basis. The digestibility of the diets was not affected by inclusion of biological solids at the 5 percent level or less. A second study was done using biological solids in the finishing diet of steers at 2.3, 4.6, and 8.9 percent biological solids. Feed efficiency was not significantly dif- ferent from the control.

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Industrial Food Processing Wastes 13 Winery Wastes Wine-making is a large industry in California, with lesser quantities being produced in New York and other states. In 1979, 2,461,324 metric tons of grapes were used for wine-making in the United States. Of this amount 96.5 percent was processed in California, 2.5 percent in New York, and the balance in other states (U.S. Department of Agriculture, 19801. Some wines are made from apples, pears, and other fruits; information on the quantity of nongrape wines produced is not available. The major wastes from wineries are stems, pomace, lees, stillage, and cleanup washwater. If distilled wines are made, the pomace becomes part of the stillage (also called still slops or still bottoms). The stillage is the residue remaining after all alcohol has been distilled. The lees are the sediments that settle out during the storage and aging of wine and that are removed during racking. Winery operations are seasonal; crushing and fermentation occurs from August to November, while distillation may continue throughout the year. The stems (approximately 5 percent of the original grape material) are usually disposed of by field spreading or burning (Stokes, 19671. Use of dried pomace as a feed declined to negligible amounts in 1966 (Amerine et al., 1972), but recently large amounts of pomace are being dehydrated for feed in California. The quantity of pomace produced has been estimated as 10 to 20 percent of the original grape weight (Ben-Gee and Kramer, 19691. Another study estimated a yield of 10 percent pomace, containing 45 percent solids (Pattee, 1947~. Amerine et al. (1972) estimated 12 percent pomace yield. The solids content of the pressed pomace may be 30 to 35 percent (J. Cooke, University of California, Davis, 1976, personal communication). Annual U.S. production of grape pomace was estimated at 45.4 to 72.6 million dry kg, and production of combined apple and pear pomace was estimated at 7.3 to 9.1 million dry kg (Prokop, 19791. In California, approximately 18.2 million dry kg are used for feed (G. Cooke, University of California, Davis, 1979, personal communication). Nutritional Value Only a few studies on the feeding value of grape pomace have been conducted, but pomace has been fed to ruminant animals in the United States and other countries for many years. The French use pomace as feed and consider it similar in quality to good hay (Amerine et al., 19721. Because of differences in wine production in the two countries, pomace from French wineries may have higher feed value. According to Amerine et al. (1972), the grape stems contain appreciable amounts of fermentable

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14 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS carbohydrate. Grape pomace has a high fiber content and lower feed value than other fruit-wine pomaces. The seed content of wet pomace ranged from 20 to 30 percent (Amerine et al., 19721. The seeds have a fibrous hull that decreases the feeding value of the pomace. If the seeds were hulled and pressed for oil extraction; the presscake would be valuable as animal feed. The pomaces are high in moisture and generally rather fi- brous. Protein and energy are noorlv divested, the digestibility of protein being ~o per`;en~ anu tne ~ values ranging from 24 to 30 percent, air-dry basis. These values were obtained in a study in which grape pomace was fed at a level higher than 50 percent of the diet, with alfalfa hay in one trial and as 100 percent of the diet in another (Forger, 19401. Prokop (1979), in a more recent study, fed grape pomace at 20 percent of the diet. Net energy values obtained with beef cattle on finishing diets were: NEm, 0.75 Mcal/kg, and NEg, 0.41 Mcal/k~ on a dry-matter basis. In the same study, a combination of apple, pear, and grape pomaces and apple pomace were also tested at the 20 percent level. On a drY-matter ~7 1 ~ ~ 1 ~1_ _ ~% T 1 - basis, the value of apple winery pomace was comparable to beet pulp. The combination was similar in nutritive value to dried alfalfa pellets (20 percent protein). The value of pear pomace was estimated at 89 percent of the value of the apple pomace (Prokop, 19791. In a recent study in Cyprus, Hadjipanayiotou and Louca (-1979) fed dried grape pomace (also called grape mare) as 15 and 30 percent of calf fattening diets. Urea was added to compensate for the low digestibility of grape pomace protein. The composition of the grape pomace was very similar to that reported by Prokop (19791. On a dry-matter basis, crude protein was 12.3 percent and was 19.5 percent digestible. The digestion coefficient for dry matter was 28.4 percent. Metabolizable energy was 1450 kcal/kg, dry-matter basis approximately half that of barley. The feed intake and gain of the calves were not significantly different when grape pomace formed 0, 15, or 30 percent of the diet. However, there was a significant difference in feed efficiency between the 0 and 30 percent levels. The dressing percentages of the calves fed 30 percent grape pomace tended to be lower. Most of the pear and apple winery pomaces are being used as feed. Some is being dried for this purpose, but most is being fed wet, (M. J. Prokop, University of California, E1 Centro, 1979, personal communi- cation). Processing Wet grape pomace stores well in compacted piles; only the outer layer deteriorates (Stokes, 19674. Large quantities can be dried in rotary drum

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Industrial Food Processing Wastes 15 driers and ground in hammer mills. Small quantities of apple and pear pomaces may be combined with the grape pomace for drying. The non- grape pomaces are more difficult to dry, and combining with grape pomace makes drying easier. The pomace not being used as feed is spread on land. Cacao (Theabroma cacao) Processing Wastes Commercial cacao beans are imported into the United States for chocolate and cocoa manufacture. Imports of cacao beans into the United States in 1979 were 167,881 metric tons (U. S. Department of Agriculture, 19801. The two major uses of cacao bean shells are as animal feed and nursery mulch. Calculated yields of shell available for by-product recovery ranged from 8 to 12 percent of the commercial beans, depending on the efficiency of winnowing, the quantity of shell-nib mixtures, and the variety of bean (Chats, 19531. Physical Characteristics The shells are brittle and, depending on the processing equipment, may be broken into fine pieces, but they are not ground intentionally at this stage. Feed manufacturers may grind the shells prior to incorporating them into feed mixtures. In California more shells are used as feed than in other areas of the country because cacao shells are not used as extensively for mulch in California, other mulches being preferred. Nutritional Value The fat content of the shells is about 3 to 3.5 percent and varies with the amount of fat transferred during roasting and the quantity of nib present (the nib is the cotyledon of the cacao from which various chocolate and cocoa products are made) (Chats, 19531. The ash content varies from 5.5 percent (Chats, 1953) to 10.8 percent (Morrison, 1956) dry-matter basis. The crude protein content is 13.5 to 16 percent but has low digestibility (Chats, 1953; Morrison, 19564. Crude fiber is 16 to 20 percent (Chats, 19531. The shells also contain considerable vitamin D (Morrison, 1956~. Fruit Pits, Fruit Pit Kernels, Nut Hulls, and Nut Shells Total U.S. nut shell and fruit pit wastes have been estimated at over 453.6 million kg annually (Mantel!, 19751. Nut shells and fruit pits are burned as fuel, made into charcoal, or used as landfill. Some of the charcoal made from nut shells and fruit pits is used in animal feeds. Shells from

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Industrial Food Processing Wastes 35 to 30 to 50 percent water and then dried separately or mixed with other meat by-products. Alwatech protein concentrate usually contains 10 percent LSA, dry- matter basis. Composition varies with the type of effluent treated; meat and fish effluents have been studied. Because the effluent is treated within 1 or 2 hours, the bacteriological condition is excellent. The product has been substituted for 50 percent fish meal or soybean meal in chick and swine diets with satisfactory results. LSA is a purified derivative from wood pulping liquors. Paulson and Lively (1979) reported on the use of activated sludge treatment and the use of activated sludge as animal feed. The initial solids content of the sludge was 0.3 to 0.6 percent. Pilot studies on thickening sludge by air flotation and centrifugation were conducted. Sludge samples were dried and analyzed. Nitrite and nitrate content were found to be less than 0.1 percent. The protein content, dry-matter basis, from several samples was 47 to 57 percent. Feeding trials were conducted with rats where sludge replaced up to 100 percent of the dietary protein. Good results were obtained when sludge provided 25 percent of the dietary protein. The rats gained weight when sludge was fed as the only protein source but at a slower rate than normal. This was probably due to the amino acid imbalance of the sludge. The sludge was analyzed for amino acids and found to have a high level of methionine compared to soybean meal. Tannery Wastes In recent years the United States has been producing about 40 million cattle hides per year, 50 percent of which are tanned by domestic tanners (M. Komanowsky and J. C. Craig, USDA Eastern Regional Research Center, Philadelphia, Pa., 1979, personal communication). When pro- cessed in the tannery only about 55 percent of the weight of the hide goes into making leather. Most of the remaining 45 percent is wasted, 5 to 10 percent as waste hair, 5 to 10 percent as dissolved proteins, 15 percent as flashings and trimmings, and 15 percent as splits. A fresh cattle hide contains 64 percent water, 33 percent protein, 2 percent fat, 0.5 percent mineral salts, and 0.5 percent other substances. The 33 percent protein is composed of 87.8 percent collagen, 6.1 percent keratin, 5.2 percent non- structural proteins (albumins, globulins, etc.), and 0.9 percent elastin. To make leather, the tanner removes most of the noncollagenous materials. Nutritional Value Wisman and Engel (1961) prepared two tannery by- product meals, referred to as partially hydrolyzed tannery by-product meal

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36 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS and unhydrolyzed, acetone extracted, tannery by-product meal. Both were made from limed hide flashings. The hydrolyzed meal contained 93.5 percent dry matter, 68.3 percent crude protein, 1.52 percent ether extract, and 23.2 percent ash. The unhydrolyzed meal contained 79.2 percent dry matter, 67.8 percent crude protein, 7.7 percent ether extract, and 4.2 percent ash. The protein of the meals contained 8.1 percent lysine, 20.9 percent glycine, 0.13 percent tryptophan, and 2.4 percent methionine. The meals were tested in poultry diets as replacements for up to 75 percent of soybean oil meal protein. Diets had constant levels of protein, energy, calcium, and phosphorus. Maximum levels of meals in poultry diets appeared to be 12.5 to 25 percent of the soybean meal protein. Responses to both meals were similar. Adding tryptophan to the diet did not improve growth rates; thus tryptophan was not considered the first limiting amino acid (Wisman and Engel, 19611. Waldroup et al. (1970) found that chicks fed 2 to 3 percent hydrolyzed leather meal replacing soybean meal performed as well as the controls even without adding supplemental amino acids. Chicks could be fed up to 8 percent leather meal when supplemented with amino acids with no significant differences between treatments. Metabolizable energy content of the leather meal was 2,920 kcal/kg, dry matter basis. Compared to soybean meal, methionine, lysine, and tryptophan were found to be low in leather meal. Dilworth and Day ~ 1970) conducted a similar experiment and also found that chicks fed 1 to 3 percent leather meal had equal or greater growth than those fed the basal diet, with or without minimum amino acid levels being specified in the diets. A study was conducted by Knowlton et al. (1976) using hydrolyzed leather scrap to replace 0 to 75 percent of soybean meal crude protein on an isonitrogenous basis in sheep diets. On a dry-matter basis the leather meal contained 75.4 percent crude protein, 1.8 percent ether extract, 18.6 percent ash, and 3.0 percent chromium. Of the many parameters measured in the study, few were affected by the inclusion of hydrolyzed leather meal in the diet at the 50 and 75 percent substitution levels. There was a decrease in apparent digestibility of crude protein at these levels. Hydro- lyzed leather meal protein had digestibility values of 81.2, 71.6, and 71.2 percent in the 25, 50, and 75 percent substitution-level diets, respectively. Several reasons suggested for the lower digestibilities were incomplete hydrolysis during processing, heat damage incurred during flash drying, tanning, or a combination of these.

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Industrial Food Processing Wastes 37 Hair Hair is available from two sources: from tannery operations that use the "save-hair system" and from slaughterhouse hog hair, which is removed by scalding and scraping. Nutritional Value Several studies have been conducted on the feeding of raw and processed hog and cattle hair. Moran et al. (1967a,b) found that raw hog hair fed to roosters was very poorly digested, with a meta- bolizable energy of only 0.58 Mcal/kg on a dry-matter basis. The energy value of the raw hog hair appeared to be derived mainly from the fat content. Hog hair contains 88.1 percent protein, 6.7 percent fat, and 2.2 percent ash, dry-matter basis. Processing under pressure (3.5 kg/cm2) at 148C for 30 minutes greatly improved the digestibility. Metabolizable energy was 2.14 Mcal/kg on a dry-matter basis. They found that both hydrogen bonding and disulfide bonding involving cystine were respon- sible for the low digestibility of protein in raw hair. The cystine content of protein in raw hair was found to be lO to 15 percent. When the hog hair was processed, cystine was reduced to 3.5 percent of the protein and glycine was noticeably increased from 4.5 to 6.4 percent. Processing hair is very similar to processing feathers, with a slightly higher temperature being required, 148C compared to 142C. In chick- growing diets, up to 5 percent of the soybean protein in a 20 percent protein corn-soybean diet could be replaced by processed hog hair with little effect on growth or feed efficiency. If processed hog hair is substituted for soy protein completely, amino acid supplementation is necessary to prevent severe growth depression. Growth depression was completely overcome by supplementation with lysine, methionine, tryptophan, and glycine, which were the first through fourth limiting amino acids, re- spectively (Moran et al., 1967a,b). Moran and Summers (1968) also studied cattle hair in chick diets. The hair had been removed from the hide following calcium hydroxide and sodium sulfide treatment. The metabolizable energy of the raw cattle hair was 1.69 Mcal/kg and was increased to 2.25 Mcal/kg, dry-matter basis, when processed in the same manner as hog hair. The cystine level in raw cattle hair was 5.34 percent of protein and was reduced to 2.92 percent by processing; glycine was increased. Changes in the amino acid content, which had not been observed when processing hog hair or feathers, showed decreases in histidine, lysine, and tyrosine. The authors suggested that this may have been caused by nonenzymatic browning. Substituting the processed cattle hair for soy protein in a 20 percent protein diet did not affect chick performance. However, if processed cattle hair was substituted

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38 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS for all of the soy protein, supplementation with methionine, lysine, tryp- tophan, histidine, and glycine was required to prevent growth depression. Kornegay and Thomas (1973) found that diets containing 2 to 3 percent processed hog hair meal could be substituted for soybean meal on a digestible protein basis without depressing growth or feed efficiency. At levels above 6 percent processed hog hair, however, feed intake was depressed. Amino acid deficiencies, imbalance, or poor availability were suggested as causes. ALTERNATIVE USES FOR FOOD PROCESSING WASTES Other than for animal feed, uses for food processing wastes have developed because of the increased cost of fossil fuels for energy. Some food pro- cessing wastes are now being used for fuel or for alcohol production. Depending upon cost of fuel, some materials (e.g.' almond hulls, fruit pits, and nut shells) may be burned as fuel rather than utilized as animal feed. Also, food processing wastes high in fermentable carbohydrates and sugars may be utilized in alcohol production. ANIMAL AND HUMAN HEALTH PROBLEMS AND REGULATORY ASPECTS Pesticide Residues The possibility of harmful pesticide residues must be considered when using crop material wastes. Pesticide use and consequent residues on crops for human consumption are regulated and monitored by federal and state agencies. Food processors have information on the pesticides used on the crops that they process. It is important that this information be obtained from the processor by those intending to use food processing waste materials for animal feed. In turn, it may often be necessary to analyze the waste material for pesticides to determine that tolerances are not exceeded. Pesticides may be present in higher concentrations on the waste material than on the total raw product received by the food processor. The reason for this is that the pesticide residues are usually on the surface of the commodity and are removed by washing, peeling, and trimming; thereby, they are concentrated in the waste material. Variable levels of pesticides were reported in apple pomace by Rumsey et al. (19771. Feeding the pomace caused significant accumulation of pesticide in depot fat of pregnant beef cows. Pesticide residues in potatoes

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Industrial Food Processing Wastes 39 were reviewed by McCoy et al. (19751. However, by-product feeds were not covered, only the whole potato and the potato parts. As with most fruits and vegetables, the residue content is higher in the peels. McCoy et al. (1975) state that potatoes, as a root crop, are less likely to carry toxic residues than above-ground crops because the pesticides must either be in the soil or translocated from the aerial part of the plant to reach the tuber. Feed use of tomato waste may be limited because insecticide levels are often higher than residue standards set for feeds (Schultz et al., 1976, 19771. Toxaphene is one pesticide involved, and the residue can be present in the waxy layer of the skin. Removal of the tomato skin would increase the value of the pomace. The adhering pulp could then be recovered for food use, as has been similarly studied with peel residue from canning. Heavy Metals Heavy metals were not found in significant quantities in the biological solids from fruit-cannery activated sludge or the carcasses of animals fed the sludges (Esvett, 19761. Chromium accumulated in tissues, particularly kidney tissue, and some in fat in chicks fed hydrolized leather meal (Dilworth and Day, 19701. Waldroup et al. (1970) reported that chromium tended to accumulate in kidneys of chicks fed 8 percent leather meal, but not in all tissues ex- amined. Chromium levels are restricted to 2.75 percent in tannery by- products fed to swine (Knowlton et al., 19761. Animal Health Apple Pomace and Nonprotein Nitrogen A serious reproductive problem was encountered when apple pomace was fed with nonprotein nitrogen (NPN) (Fontenot et al., 1977~. Apple pomace fed with urea or biuret, or a combination of these, lowered feed con- sumption and increased body weight losses when compared to corn silage and NPN, and also when compared to apple pomace and protein supple- ment. Feeding apple pomace and NPN had several serious detrimental effects including high incidence of dead, weak, or deformed calves (Bov- ard et al., 19771. No explanation has been given for the effects of feeding apple pomace and NPN. Reproductive problems were not encountered when feeding apple pomace with protein supplements. Feeding apple pomace with NPN in any form should be avoided.

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40 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS Cacao Processing Wastes The factors that limit cacao processing wastes as feed are theobromine (0.75 to 1.3 percent in shell) and caffeine (Chats, 19531. Plain chocolate contains 3 percent theobromine and 0.1 percent caffeine (Curtis and Grif- fiths, 19721. Chatt (1953) reported adverse effects if theobromine intake exceeds 0.025 g/kg body weight. In horses, theobromine intake at the level of 0.027 g/kg body weight has caused death. No waste containing theobromine should be fed to racehorses because it may cause reactions similar to doping. Cacao shells should only be fed to mature cattle at a maximum level of 2.5 percent of the diet or a maximum of 0.907 kg/day. It should not be fed to pigs, poultry, or calves because the cumulative effect is detri- mental (Chats, 19531. Calves fed 5 to 10 percent chocolate waste exhibited hyperexcitability, exaggerated gaits, and excessively alert appearance; one calf died (Curtis and Griffiths, 19721. SUMMARY Many researchers emphasize the variability of food processing wastes. The reasons for this variability are the variability of the raw food material being processed, the differences in production processes employed by different plants, and the different food products produced from the same raw material. Most of the food processing wastes have substantial nutritional value. A characteristic of most of these wastes is the high moisture, which results in high transportation and dehydration costs per unit of nutrient. Fruit and vegetable processing wastes are generally low in protein and may be limited in energy value; they are probably best suited for feeding to rum- inants. Animal processing wastes are generally high in protein, and the protein is usually high in quality. Feeding of wastes usually does not adversely affect animal performance if appropriate levels are included in the diet. Wastes can be processed by dehydration, but frequently this is not economically feasible. For many wastes, ensiling appears to be feasible. High-moisture materials should be combined with drier materials for good ensiling; the dry materials could consist of poor quality hay or crop res- idues. Although caution should be exercised, the feeding of food processing wastes does not appear to pose a serious threat to animal and human health. Pesticide levels need to be monitored. Caution should be used not to feed apple pomace in combination with nonprotein nitrogen to avoid

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Industrial Food Processing Wastes 41 reproductive problems. Wastes such as cacao processing waste, which may contain harmful levels of certain drugs, should be limited to safe levels. LITERATURE CITED Amerine, M. A., H. W. Berg, and W. V. Cruess. 1972. Technology of Wine Making. Westport, Conn.: AVI. Ammerman, C. B., L. R. Arrington, P. E. Loggins, J. T. McCall, andG. K. Davis. 1963. Nutritive value of dried tomato pulp for ruminants. J. Agric. Food Chem. 11:347. Ammerman, C. B., R. H. Harms, R. A. Dennison, L. R. Arrington, and P. E. Loggins. 1965. Dried Tomato Pulp, Its Preparation and Nutritive Value for Livestock and Poultry. Fla. Agric. Exp. Stn. Bull. No. 691. Backhoff, H. P. 1976. Some chemical changes in fish silage. J. Food Technol. 11:353. Ben-Gera, I., and A. Kramer. 1969. The utilization of food industries wastes. Adv. Food Res. 17:77-152. Bond, J., and P. A. Putnam. 1967. Nutritive value of dehydrated sweet potato trimmings fed to beef steers. J. Agric. 15:726. Bough, W. A., and D. R. Landes. 1976. Recovery and nutritional evaluation of protein- aceous solids separated from whey by coagulation with chitosan. J. Dairy Sci. 59(11): 1874. Bovard, K. P., T. S. Rumsey, R. R. Oltjen, J. P. Fontenot, and B. M. Priode. 1977. Supplementation of apple pomace with nonprotein nitrogen for gestating beef cows. II. Skeletal abnormalities of calves. J. Anim. Sci. 46:523-531. Brandt, J. A., B. C. French, and E. V. Jesse. 1978. Economic Performance of the Pro- cessing Tomato Industry. Giannini Foundation Information Series No. 78- 1. Univ. Calif. Div. Agric. Sci. Bull. 1888. Brown, A. H., W. D. Ramage, and H. S. Owens. 1950. Progress in processing pear canning waste. Food Packer 31(7):30 and 31(8):50. Brugman, H. H., and H. C. Dickey. 1955. Potato Pulp as Feed for Livestock. Maine Agric. Exp. Stn. Bull. No. 539. Brugman, H. H., and H. C. Dickey. 1961. Potato Pulp as a Feed for Livestock. Maine Agric. Exp. Stn. Bull. No. 599. Burris, M. J., and B. M. Priode. 1957. The Value of Apple Pomace as a Roughage for Wintering Beef Cattle. Va. Agric. Exp. Stn. Res. Rep. 12. Chatt, E. M. 1953. Cocoa: Cultivation, Processing, Analysis. New York: Interscience. Clark, W. S. 1979. Our industry today: Whey processing and utilization, major whey product markets 1976. J. Dairy Sci. 62:96-98. Colston, N. V., and C. Smallwood, Jr. 1972. Waste control in the processing of sweet potatoes. Pp. 85-98 in Proc. Third Natl. Symp. Food Process. Wastes. EPA-R2-72- 018. Cruess, W. V. 1958. Commercial Fruit and Vegetable Products, 4th ed. New York: McGraw- Hill. Curtis, P. E., and J. E. Griffiths. 1972. Suspected chocolate poisoning of calves. Vet. Rec. 90:313. Damron, B. L., A. R. Eldred, S. A. Angalet, J. L. Fry, and R. H. Harms. 1974. Eval- uation of activated citrus sludge as a poultry feed ingredient. Pp. 142-154 in Proc. Fifth. Natl. Symp. Food Process. Wastes. EPA 660/2-74-0s8. Della Monica, E. S., C. H. Huhtanen, and E. O. Strolle. 1975. Stability of protein water concentrates from potato starch factory waste effluents. J. Sci. Food Agric. 26:617-623.

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42 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS Dickey, H. C., H. A. Leonard, S. D. Musgrave, and P. S. Young. 1971. Nutritive char- acteristics of dried potato by-product meal for ruminants. J. Dairy Sci. 54:876-879. Dilworth, B. C., and E. J. Day. 1970. Hydrolyzed leather-meal in chick diets. Poult. Sci. 49(4): 1090. D'Mello, J. P. F., and C. T. Whittemore. 1975. Nutritive value of cooked potato flakes for the young chick. J. Sci. Food Agric. 26:261. Edmond, J. B., and G. R. Ammerman. 1971. Sweet Potatoes: Production, Processing, Marketing. Westport, Conn.: AVI. Esselen, W. B., Jr., and C. R. Fellers. 1939. The nutritive value of dried tomato pomace. Poult. Sci. 18(1):45. Esvett, L. A. 1976. Fruit Cannery Waste Activated Sludge as a Cattle Feed Ingredient. Environ. Prot. Technol. Ser. EPA/2-76-253. Folger, A. H. 1940. The Digestibility of Ground Prunes, Winery Pomace, Avocado Meal, Asparagus Butts, and Fenugreek Meal. Univ. Calif. Exp. Stn. Bull. 635. Fontenot, J. P., K. P. Bovard, R. R. Oltjen, T. S. Rumsey, and B. M. Priode. 1977. Supplementation of apple pomace with nonprotein nitrogen for gestating beef cows. I. Feed intake and performance. J. Anim. Sci. 45:513-522. Gildberg, A., and J. Raa. 1977. Properties of a propionic acid/formic acid preserved silage of cod viscera. J. Food Technol. 28:647. Gillies, M. T. 1978. Animal Feeds from Waste Materials. Food Technology Review No. 46. Park Ridge, N.J.: Noyes Data Corporation. Graham, R. P., A. D. Shepherd, A. H. Brown, and W. D. Ramage. 1952. Advanced fruit- waste recovery. Food Eng. 24:82. Grames, L. M., and R. W. Kueneman. 1969. Primary treatment of potato processing wastes with by-product feed recovery. Water Pollut. Control Fed. 41(7):1358-1367. Grant, R. A. 1976. Protein recovery from meat, poultry and fish processing plants. In Food from Waste, G. G. Birch, K. J. Parker, and J. T. Worgan, eds. London: Applied Sci- ence. Gray, L. R., and M. R. Hart. 1972. Caustic Dry Peeling of Cling Peaches to Reduce Water Pollution: Its Economic Feasibility. USDA ERS Agric. Econ. Rep. 234. Guilbert, H. R., and W. C. Weir. 1951. Pear pulp and pear molasses: Nutritional value for cattle and palatability to sheep tested in feeding trials with commercial products. Calif. Agric. 5:6. Guttormsen, K., and D. A. Carlson. 1970. Status and research needs of potato processing wastes. Pp. 27-38 in Proc. First Natl. Symp. Food Process. Wastes. EPA-12060-04/ 70. Hadjipanayiotou, M., and A. Louca. 1979. A note on the value of dried citrus pulp and grape mare as barley replacements in calf fattening diets. Anim. Prod. 23:129-132. Hallmark, D. E., J. C. Ward, H. C. Isaksen, and W. Adams. 1978. Protein recovery from meat packing effluent. Pp. 288-305 in Proc. Ninth Natl. Symp. Food Process. Wastes. EPA-600/2-78- 188. Hendrickson, R., and W. Kesterson. 1965. By-Products of Florida Citrus, Composition, Technology, and Utilization. Univ. of Florida, Gainesville, Agric. Exp. Stn. Bull. 698. Hillyer, C. M., and C. T. Whittemore. 1975. Intake by piglets of diets containing cooked potato flake. J. Sci. Food Agric. 26:1215. Hinks, C. E., D. G. Peers, and I. W. Moffat. 1975. The nutritive value of cooked potato in milk replacers for young calves. J. Sci. Food Agric. 26:1219-1224. Hinman, N. H., W. N. Garrett, J. R. Dunbar, A. K. Swenerton, and N. E. East. 1978. Tomato pomace scores well as sheep feed. Calif. Agric. 32(8):12.

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Industrial Food Processing Wastes 43 Hogan, J. M., and M. E. Highlands. 1975. Potato and potato products for livestock feed. Pp. 639-645 in Potato Processing. Westport, Conn.: AVI. Jewell, W. J. 1975. Egg Breaking and Processing Waste Control and Treatment. Environ. Prot. Technol. Ser. EPA-660/2-75-019. Jones, H. R. 1973. Waste Disposal Control in the Fruit and Vegetable Industry. Pollution- Technology Review No. 1. Park Ridge, N.J.: Noyes Data Corp. Jones, H. R. 1974. Pollution Control in the Dairy Industry. Pollution Technology Review No. 7. Park Ridge, N.J.: Noyes Data Corp. Jones, R. H., J. T. White, and B. L. Damron. 1975. Waste Citrus Activated Sludge as a Poultry Feed Ingredient. EPA-660/2-75-001. Juengst, F. W., Jr. 1979. Use of total whey constituents Animal feed. J. Dairy Sci. 62(1): 106- 111. Katsuyama, A. M., N. A. Olson, R. L. Quirk, and W. A. Mercer. 1973. Solid Waste Management in the Food Processing Industry. National Canners Association. EPA PB219- 019. Available from NTIS. Knowlton, P. H., W. H. Hoover, C. J. Sniffen, C. S. Thompson, and P. C. Belyea. 1976. Hydrolyzed leather scrap as a protein source for ruminants. J. Anim. Sci. 43(5):1095. Kornegay, E. T., and H. R. Thomas. 1973. Evaluation of hydrolyzed hog hair meal as a protein source for swine. J. Anim. Sci. 36(2):279. Livingston, A. L., R. E. Knowles, J. Page, D. D. Kuzmicky, and G. O. Kohler. 1972. Processing of cauliflower leaf waste for poultry and animal feed. J. Agric. Food Chem. 20(1):277-281. Livingston, A. L., R. E. Knowles, R. H. Edwards, and G. O. Kohler. 1974. Processing of pimento waste to provide a pigment source for poultry feed. J. Sci. Food Agric. 25:483-490. Livingston, A. L., R. E. Knowles, R. H. Edwards, and G. O. Kohler. 1976. Processing of fresh artichoke trimmings for use in animal feeds. J. Agric. Food Chem. 24(6): 1158- 1161. Lofgreen, G. P., and M. Prokop. 1979. Citrus peel liquor as an energy source in cattle growing rations. In Calif. Feeders Day Rep. Univ. Calif. Dept. Anim. Sci., Coop. Ext. Imperial Valley Field Stn. Mantell, C. L. 1975. Nut Shells and Fruit Pits in Solid Wastes: Origin, Collection, Pro- cessing and Disposal. New York: Wiley-Interscience. McCoy, C. M., and S. E. Smith. 1940. Tomato pomace in the diet. Science 91:388. McCoy, C. M., J. B. McCoy, and O. Smith. 1975. The nutritive value of potatoes. Pp. 235-273 in Potato Processing. Westport, Conn.: AVI. Messersmith, T. L. 1973. Evaluation of dried paunch feed as a roughage source in ruminant finishing rations. M.A. thesis. Department of Animal Science, University of Nebraska. Moran, E. T., Jr., and J. D. Summers. 1968. Keratins as sources of protein for the growing chick. 4. Processing of tannery by-product cattle hair. Poult. Sci. 47(2):570. Moran, E. T.' Jr., J. D. Summers, and S. J. Slinger. 1967a. Keratins as sources of protein for the growing chick. 2. Hog hair, a valuable source of protein with appropriate pro- cessing and amino acid balance. Poult. Sci. 46(2):456-465. Moran, E. T., Jr., H. S. Bayley, and J. D. Summers. 1967b. Keratins as sources of protein for the growing chick. 3. The metabolizable energy and amino acid composition of raw and processed hog hair meal. Poult. Sci. 46(3):548. Morrison, F. B. 1956. Feeds and Feeding, 22nd ed. New York: Morrison Publishing. National Research Council. 1976. Nutrient Requirements of Beef Cattle. Washington, D.C.: National Academy of Sciences.

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44 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS Osten, B. J. 1976. Protein from potato starch mill effluent. P. 196 in Food From Waste, G. G. Birch, K. J. Parker, and J. T. Worgan, eds. London: Applied Science. Pailthorp, R. E., J. W. Filbert, and G. A. Richter. 1975. Waste disposal. P. 646 in Food Processing. Westport, Conn.: AVI. Pattee, E. C. 1947. Winery Waste Recovery. Cincinnati: Research Division, National Distillers Products Corp. Patton, R. S., and P. T. Chandler. 1975. In vivo digestibility evaluation of chitinous materials. J. Dairy Sci. 58:397-403. Paulson, W. L., and L. D. Lively. 1979. Oxidation Ditch Treatment of Meatpacking Wastes. EPA-600/2-79-030. Pennington, H., and F. Husby. 1979. University of Alaska fishmeal research. Univ. of Alaska, Alaska Seas and Coasts 7(1):6-8. Prokop, M. 1979. Dried winery pomace as an energy source in cattle finishing rations. In Calif. Feeders Day Rep. Univ. Calif. Dept. Anim. Sci., Coop. Ext. Imperial Valley Field Stn. Ricci, R. 1977. A Method of Manure Disposal for a Beef Packing Operation. First Interim Tech. Rep. EPA-600/2-77-103. Richter, G. A., K. L. Sirrine, C. I. Tollefson. 1973. Conditioning and disposal of solids from potato waste water treatment. J. Food Sci. 38:218-224. Rogers, C. J., and W. E. Coleman. 1978. Protein from Aspergillus niger grown on starchy waste substrate in animal feeds. Waste Mater. Food Technol. Rev. 46:139. Rosenau, J. R., L. F. Whitney, and R. A. Elizondo. 1976. Low waste water potato starch/ protein production process Concept, status, and outlook. Pp. 118- 128 in Proc. Seventh Natl. Symp. Food Process. Wastes. EPA-600/2-76-304. Rosenau, J. R., L. F. Whitney, and J. R. Haight. 1977. Potato juice processing. Pp. 284- 291 in Proc. Eighth Natl. Symp. Food Process. Wastes. EPA-600/2-77-184. Rosenau, J. R., L. F. Whitney, and J. R. Haight. 1978. Economics of starch and animal feed production from cull potatoes. Pp. 89-99 in Proc. Ninth Natl. Symp. Food Process. Wastes. EPA-600/2-78- 188. Samuels, W. A., J. P. Fontenot, K. E. Webb, Jr., and V. G. Allen. 1982. Ensiling of seafood waste and low quality roughages. VPI and State Univ. Anim. Sci. Res. Rep. 2: 175. Schingoethe, D. J. 1976. Whey utilization in animal feeding: A summary and evaluation. J. Dairy Sci. 59(3):556. Schultz, W. G., R. P. Graham, and M. R. Hart. 1976. Pulp recovery from tomato peel residues. Pp. 105-117 in Proc. Sixth Natl. Symp. Food Process. Wastes. EPA-600/2- 76-224. Schultz, W. G.' H. J. Neumann, J. E. Schade, J. P. Morgan, P. F. Hanni, A. M. Kat- suyama, and H. J. Maagdenberg. 1977. Commercial feasibility of recovering tomato peeling residuals. Pp. 119- 136 in Proc. Eighth Natl. Symp. Food Process. Wastes. EPA- 600/2-77- 184. Skogman, H. 1976. Production of symba-yeast from potato wastes. In Food From Waste, G. G. Birch, K. J. Parker, and J. T. Worgan, eds. London: Applied Science. Smallwood, C., R. S. Whitaker, and N. V. Colston. 1974. Waste Control and Abatement in the Processing of Sweet Potatoes. Environ. Prot. Technol. Ser. EPA-660/2-73-021. Smith, T. J. 1976. Dry peeling tomatoes and peaches. Pp. 194-203 in Proc. Sixth Natl. Symp. Food Process. Wastes. EPA-600/2-76-224. Smock, R. M., and A. M. Neubert. 1950. Apples and Apple Products. New York: Inter- science. Soderquist, M. R., and K. J. Williamson. 1975. Fish and shellfish wastes. In Solid Wastes: Origin, Collection, Processing and Disposal. New York: Wiley-Interscience.

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Industrial Food Processing Wastes 45 Stabile, R. L., V. A. Turkot, and N. C. Aceto. 1971. Economic analysis of alternative methods for processing potato starch plant effluents. Pp. 185-202 in Proc. Second Natl. Symp. Food Process. Wastes. EPA-12060-03/71. Stokes, R. D. 1967. An evaluation of current practices in the treatment of winery wastes. M.A. thesis. University of New South Wales, Australia. Summerfelt, R. C., and S. C. Yin. 1974. Paunch manure as a feed supplement in channel catfish farming. Pp. 246-257 in Proc. Fifth Natl. Symp. Food Process. Wastes. EPA- 660/2-74-046. Treadway, R. H. 1975. Potato starch. P. 546 in Potato Processing. Westport, Conn.: AVI. Tsatsaronis, G. C., and D. G. Boskou. 1975. Amino acid and mineral salt content of tomato seed and skin waste. J. Sci. Food Agric. 26:421-423. U.S. Department of Agriculture. 1980. Agricultural Statistics. Washington, D.C.: U.S. Department of Agriculture. Waldroup, P. W., C. M. Hilliard, W. W. Abbott, and L. W. Luther. 1970. Hydrolyzed leather meal in broiler diets. Poult. Sci. 49(5):1259. Walter, R. H., J. B. Bourke, R. M. Sherman, R. G. Clark, E. George, Jr., A. B. Karasz, R. Pollman, S. E. Smith, and G. Lake. 1975. Apple pomace in the dairy regimen. Cornell Univ., Geneva, New York. Food Life Sci. 8:12-13. Whittemore, C. T., A. G. Taylor, I. W. Moffat, and A. Scott. 1975. Nutritive value of raw potato for pigs. J. Sci. Food Agric. 26:255. Wilson, L. L. 1971. Adipose tissue concentrations of certain pesticides in steers fed apple waste during different parts of the finishing period. J. Anim. Sci. 33:1356-1360. Wisman, E. L., and R. W. Engel. 1961. Tannery by-product meal as a source of protein for chicks. Poult. Sci. 40(6): 1761. Witherow, J. L. 1974. Paunch handling and processing techniques. Nat. Provis. 10:14. Witherow, J. L., and S. Lammers. 1976. Paunch and viscera handling. Pp. 37-66 in Workshop (1973) on In-plant Waste Reduction in the Meat Industry, compiled by J. L. Witherow and J. F. Scaief. Environ. Prot. Technol. Ser. EPA-600/2-76-214.