A Buyer’s Guide To Rendered Fats

Buyer’s Guide Continued from page 15terms of percent FFAs. The assumption usually made in thecalculation is that the acids have a molecular weight equalto that of an oleic acid. The relation between acid value andpercent FFAs calculated as oleic is as follows: one unit of acidvalue 0.503 percent FFAs.i) Free fatty acids as oleic, % milliliter (ml) of alkali x N x 28210 x weight of sampleii) Free fatty acids as lauric, % ml of alkali x N x 20010 x weight of sampleiii) Free fatty acids as palmitic, % ml of alkali x N x 25610 x weight of sampleNote – N normality or strength of alkali. 282, 200, 256 molecular weights of the respective fatty acids.In many types of fats and oils the percentage of FFAsis calculated as oleic acid, but with coconut and palm kerneloils it is expressed in terms of lauric acid and in palm oil aspalmitic acid.Biodiesel plants having either a pre-treatment system oracid esterification system can make use of higher FFA fats/oils.The price of the product should generally reflect the yield lossor increased processing cost compared to a low FFA fat/oil.tallow. A low FFA results in a high glycerin yield for thesoap manufacturer. Similarly, a low color tallow enables themanufacturer to produce high quality white bath soap or highquality fatty acids.A refined and bleached analysis determines the Lovibondcolor of the sample after treatment with alkali and a specifiedbleaching earth. The Lovibond color is a much finer colorreading compared to the FAC color standards. The color isreported as red and yellow. For example, a good extra fancytallow will read 0.5 red and five yellow. In reading tallow, theyellow is 10 times the red (0.5 x 10 five yellow).The biodiesel producer will see a color impact slightly inthe fuel color, but mostly in the glycerin product. Very darkglycerin may be discounted in the market, depending on theend use of the glycerin.Moisture, Impurities, UnsaponifiablesA sample of fat is weighed and the moisture is boiled off.The weight loss is calculated as the moisture content.The recommended moisture level is one percent or less.Moisture can reduce the energy of a fat both by dilution andby causing an increase in the FFA content. Some condensationmoisture is unavoidable with any feeding fat; however, itshould be kept at a minimum. Moisture at low levels functionsmuch like an antioxidant, but at higher concentrations is apro-oxidant presumably because if can solubilize tracemetals (Bailey’s IndustrialOil and Fat Products, 4thTable 4. Chemical Data of Feed Grade Fats: Average ValuesEdition, vol. 1, p.147). C%Max.Iodine% Fatty AcidsMoisture accumulates in theSat.Unsat. Linoleic lower strata of fat storageFat SourceTiterMIU% FFAValueU/SFGF – for all feeds29-452-44040-1001.0–3.025-50 50-754-40units, which makes samplingFGF – for milk replacers38-4115471.050504difficult. Therefore, prior toBeef tallow38-4315471.050504sampling fat in storage, itPork fat32-37215681.6386212should be thoroughly mixedPoultry fat28-33215852.6287220by mechanical agitation.Acidulated vegetableImpurities are nonsoapstock28-354-670324.120802hazardous filterable materialsPalm oil28-3625531.4425810not soluble in petroleumFGF Feed grade fatether.However, impuritiesU/S Unsaturate/Saturate ratiocan create physical problemsas they settle to createColortank sludge and ultimately clog valves, lines, and nozzles.FAC is the abbreviation for the Fat Analysis Committee Impurities could be meat and bone particles remaining in theof the American Oil Chemists’ Society. A sample of fat is tallow after the rendering operation even though it is filtered,filtered then compared with standard color slides mounted on or it could be foreign materials such as sand or metal particlesa circular aperture. FAC color standard runs from one to 45 picked up after processing during storage and/or transport.The same sample that moisture was determined from isusing odd numbers divided into five series for grading:filtered through a fine filter paper using a solvent. The weight 1-9 light colored fatsof the material left on the filter paper is a measure of the 11, 11A, 11B, 11C very yellow fatsinsoluble impurities. 13-19 dark, reddish fatsUnsaponifiables, or “unsaps,” refers to any material 21-29 greenish fatswithin the tallow that will not saponify (convert into soap) 31-45 very dark fatsThe different series are somewhat independent so there is when mixed with an alkali. This basically covers componentsno orderly increase in the color from the lowest to the highest of the tallow that are not triglycerides such as plant sterols andnumbers, i.e., fats graded 21-29 may actually be lighter than pigments. A major portion of the unsap fraction is from plantthose graded 13-19. The FAC method is used when fats are sterols originating from the gut contents (forages, grains) ofrendered offal. The determination of unsap content is basedtoo dark or green to be read by the Lovibond method.Many customers require low FFA and color so that they upon saponification followed by extraction with solvents andcan maximize the yield of products they manufacture from washing.16February 2009 Renderwww.rendermagazine.com

Biodiesel producers should request as low a value ofmoisture, impurities, and unsaponifiables as possible as thesewill impact biodiesel end product quality. Moisture in thefats/oils will generate soaps in the methylester that must beremoved and will interfere with the separation process of theglycerin.Formation of soaps also interferes with the catalyst,binding it and increasing cost through increased need formethanol and catalyst. The unsap portion is also an indicatorof likely filterability issues in the finished product and willneed to be removed from the methylester, if it has not beenremoved from the oil prior to transesterification.PolyethyleneAlmost all tallow contains polyethylene (PE), which isa foreign material in tallow, to some degree. It finds its wayinto the rendering plant as meat wrappers mixed in with theraw material. Most of the polyethylene wrappers used by themeat industry are of low density type that will melt at lowertemperatures and stay soluble in the tallow.At present the only feasible means of removing PE fromtallow is to filter the tallow at low temperature using specialfilter aids. Most tallow consumers say they could stand up to30 parts per million (ppm) while others indicate they couldtake as high as 200 ppm.The problem with PE is that it does not stay soluble in allthe various stages of the manufacturing process. In particular,if there is a sharp temperature drop the PE will come outof solution. With soap manufacturers it has been knownto adhere to the inside wall of pipes and after it builds updarkened pieces flake off that later show up in the finished barsoap. It has also been known to cause blockage in fatty acidmanufacturing plants and can coat the catalyst.In biodiesel production, the PE will act the same asunsaps and will drop out of the methylester when it is exposedto sharp temperature drops.TiterTiter is a measure of the solidification point of a fat afterit has been saponified and the soaps reacidulated to FFAs. Itis determined by melting the resulting fatty acid, and whileslowly cooling, measuring the congealing temperature indegrees centigrade.The titer is an important characteristic of inedible fatsused for soap making to make harder soap, or as raw materialsfor fatty acid manufacture, and is also an indication of thefirmness of natural edible fats such as lard. Under the acceptedUnited States trading rules, inedible fats with titers below 40degrees centigrade are classed as grease and those with highertiters are classed as tallow. Minimum titers are also specifiedfor the different grades.A good rule of thumb is when a sample of tallow staysliquid in a warm room, it has a low titer and if it hardens in awarm room it has a high titer. The reason for fat to have a highor low titer is due to its constituent saturated and unsaturatedfatty acids (the higher the degree of unsaturation, the lowerthe titer).Titer cannot be changed in the rendering plant; however,it can be greatly increased by a hydrogenation process inwhich hydrogen is added to the unsaturated bonds.www.rendermagazine.comTable 5. Typical Fatty Acid Profiles of Tallow andYellow GreaseTallowFatty 2.3Linolenic0.2Yellow GreaseFatty 0.6-2.5Table 6. Ranges of Titers for Different Fats and OilsFat or OilBabassu oilBeef tallowCastor oilCoconut oilCorn oilCottonseed oilLardLinseed oilOlive oilPalm oilPalm kernel oilPeanut oilRapeseed oilSardine oilSesame oilSoybean oilWhale oil 0-2826-3211-1527-2820-2521-2322-24Iodine ValueThe iodine number is a measure of the chemicalunsaturation of the fat and the results are expressed as thenumber of grams of iodine absorbed by 100 grams of fatsample. Iodine value (IV) can be used to estimate fat structureand unsaturation-saturation ratios. Unsaturated fats havehigher IVs than saturated fats, so the higher the IV, the softerthe fat and lower the titer.Rate of FiltrationThis method was originated by Proctor and Gamble toensure they were receiving clean tallow. Fats that will giveprocessing difficulties such as slow filtration, emulsions, andfoaming can be detected by this filtration method. The methodis based on the amount of fat that will filter in a specified timeunder standard conditions.The results from this test could run 40, which means 40milliliters of tallow at 230 degrees Fahrenheit (110 degreesCelsius) passed through the filter paper in five minutes. Proctorand Gamble likes to purchase tallow with 35 to 40 rate of filtration. (Filter paper is VWR International, LLC, grade 417.)Continued on page 18Render February 200917

Buyer’s Guide Continued from page 17Microscopic fines, polyethylene, and plant gums fromthe raw material could cause a slow filtration by plugging thepores of the filter paper, thus resulting in a very low rate offiltration. Tallow that has been water washed or pre-filteredwill generally run a high rate of filtration due to removal offines and gum.This test can be helpful to biodiesel producers as apredictor of issues with filterability of finished methylester,but the rate of filtration must be calibrated to the specificbiodiesel process. This test has not been correlated to theASTM cold soak filtration test. Such a correlation betweenraw materials, processing parameters, and the finished producttest might benefit the biodiesel and rendering industries asboth try to understand field performance of biodiesel undervarious temperature and equipment conditions.Pesticide ResiduesReputable renderers have implemented goodmanufacturing practices that prevent accidental contaminationof rendered products by exposure to crop chemicals andPCBs. Hazard analysis and critical control point programsdictate products are not released for sale until being certifiedthat U.S. Food and Drug Administration specifications areTable 7. Final Melting Points of Average Samples ofFats and OilsFat or OilBabassu oilBeef tallowButterfatCocoa butterCoconut oilCottonseed oilLard, prime steamPalm oil (refined)Palm kernel oilPeanut oilHydrogenated OilsCastorCottonseedSardineSoybean C26503736261145402913876057.566.5Table 8. Iodine and Saponification Value of Samplesof Vegetable Oils and Animal FatsFat or OilIodine ValueCoconut oil7.5-10.5Corn oil103-128Cottonseed oil99-113Lard, prime steam53-77Palm oil44-58Soybean oil120-141Tallow – beef35-48Tallow – goat33.5Tallow – mutton41.218February 2009 RenderSaponification -202199197not exceeded. Some of these pesticide residues and theirmaximum levels are: DDT, DDD, DDE - 0.5 ppm; Dieldrin- 0.3 ppm; and PCB - 2.0 ppm. The method of analysis is bygas chromatography.Saponification ValueThis is an estimate of the mean molecular weight of theconstituent fatty acids in a fat sample and is defined as thenumber of milligrams of potassium hydroxide required tosaponify one gram of the fat. The higher the saponificationvalue, the lower the mean chain length of the triglycerides.Boehmer Number (Applied to Lard)This test is used to determine if tallow is mixed with lard.For pure lard, the number should be greater than 73. If lessthan 73, it indicates contamination.Fatty Acid ProfileThe fat is saponified and then methyl esters are formed.These methyl esters of the component fatty acids are theninjected onto a gas chromatograph column and the fatty acidsTable 9. Quality Control Analysis with ApproximateRunning b ed and bleachedPolyethyleneTiterBleach testRate of filtrationRefining lossIodine valueSaponification valueFatty acid profileProteinFatAshProtein digestibilityYield testAlkalinity, phenophthaleinAlkalinity, methylChloridesSulphitepHPhosphateTotal dissolved solidsHardnessAflatoxinPesticide residue/PCBsChick edemaMicroscopic checkMicroscopic test (complete)GossypolTime Involved5 minutes5 minutes15 minutes10 minutes3 hours2 hours2 hours4 hours25 minutes30 minutes6.5 hours2 hours3 hours30 minutes2 hours2.5 hours2.5 hours28 hours8 hours20 minutes20 minutes20 minutes20 minutes5 minutes20 minutes5 minutes15 minutes30 minutes - 3 hours8 hours8 hours15 minutes4 hours3 hourswww.rendermagazine.com

are separated due to their differing solubility in the liquidphase of the column. The fatty acids elute from the columnand are burnt in a hydrogen flame. The increased electricactivity generated by the incineration is recorded and thepercent fatty composition of the fat calculated.With the development of column technology, the fattyacid composition can be determined within 20 minutes of thesample being taken.Total Fatty AcidsFat quality is determined by energy value, stability, andfreedom from extraneous materials. Total fatty acids (TFAs)are comprised of both free fatty acids and those combined withglycerol (intact glycerides). Fat is composed of approximately90 percent fatty acids and 10 percent glycerol. Glycerolcontains about 4.32 calories per gram compared with 9.40calories per gram for fatty acids. Since fatty acids containover twice the energy of glycerol and are the primary energysource in feeding fats, the TFA content acts as one indicator ofenergy. TFA levels less than 90 percent reflect dilutions withother ingredients and the value should be discounted on totalfatty acid content.LeadThe U.S. Food and Drug Administration specification forlead is 7.0 ppm. Lead is considered to be a toxic substance inconcentrations greater than this level. The methods of analysisare by atomic absorption, inductive-coupled plasma analysis,or by ultraviolet spectrophotometry.www.rendermagazine.comPeroxide ValueThe peroxide value (PV) method is a common way ofassessing fat rancidity. Rancidity is primarily caused byoxidation with hydroperoxides being the first oxidationproducts formed. The PV method measures their formationby determining the amount of iodine liberated from theirreaction with potassium iodide and expressing the result inmilli-equivalents per kilogram (meq/kg). Hydroperoxidesare further oxidized to aldehydes and ketones, which areresponsible for the changes in odor and flavor of rancid fats.The human threshold for detecting these changes seems tocorrespond to a PV of about 40 meq/kg. If a fat has a PV lessthan 40 meq/kg and does not smell rancid, it is most likely inthe initial stages of oxidation and can readily be used in feedrations. If the PV is less than 40 meq/kg and the fat smellsrancid, it is likely in its later stages of oxidation.ConclusionWhile the above are industry standards andrecommendations, biodiesel producers looking to buyrendered fats should know the specifications required by theirparticular process and communicate those requirements to thesupplier, who may be able to supply products lower than themaximum value at an appropriate premium to the publishedcommodity prices.Commodity prices are for those products typical or evenat the limits of the ranges and may not reflect prices for betterthan average values. RRender February 200919

A Buyer’s Guide to Rendered Fats Editor’s Note – The following information has been excerpted from the Pocket Information Manual: A Buyer’s Guide to Rendered Products published by the National Renderers Association. The complete