JOURNAL OF FOOD SCIENCE ENGINEERING/PROCESSING

Properties and Utilization of from an Advanced Recovery System

C. M. Calhoun, T. D. Schnell, and R. W. Mandigo

ABSTRACT may be an economical and highly functional ingredient in ground Pork trim from an advanced meat recovery system, referred pork formulations. to as pork trim-finely textured (PTFT), was characterized and In this study, meat from AMR, referred to as pork trim-finely compared to 80% lean ground pork (GP) and knife trimmed textured (PTFT), was analyzed for inherent properties and compared lean (KT). PTFT (0, 5, 10, 15%) was incorporated into 10% and to ground pork and to lean removed from bone by knife trimming. In 20% fat ground pork patties. PTFT had higher total pigment, a second part of the study, PTFT was incorporated into ground pork cholesterol, iron and calcium and lower collagen than GP or patties to determine an acceptable level of incorporation based on final KT. Fat content of PTFT was similar to GP and KT. PTFT in- product attributes. creased redness and juiciness and decreased hardness, chewiness and cohesiveness of ground pork patties. Addi- MATERIALS & METHODS tion of up to 15% PTFT caused differences which were per- ceived as improvements in quality. PTFT can be a replace- Properties of PTFT ment for pork trim in ground pork products. Sample collection. Untrimmed pork bones from market weight Key Words: meat recovery, pork, PTFT, mechanically re- hog carcasses were processed by a Protecon TL60 (Stork Protecon, covered meat Inc., Gainesville, GA) followed by a Baader 605 Lean Separator (Baader North America Corp., New Bedford, MA) at a commercial meat plant to remove PTFT. The temperature of the bones before recovery was maintained between 2 and 7ЊC. The machine applied INTRODUCTION 160-180 bar pressure to the bones for a dwell time of 2s. The yield of ADVANCED MEAT RECOVERY (AMR) SYSTEMS HAVE BEEN INTRO- meat recovered from bone was 35% of the original bone weight. Meat duced to aid in recovery of meat from trimmed bones, while at the same from the bones exited the compaction chamber through concentric time, reducing the incidence of repetitive motion syndrome to meat rings that created slots 4 mm wide by 72 mm long. The meat passed packing employees. The AMR system were utilized (Protecon TL60/ through 1.3 mm diameter holes on the screen of the Baader 605. The Baader 605 Lean Separator) recovered lean tissue using a hydraulic bones included backbone (lumbar and thoracic vertebrae), neckbone piston in a chamber which compacted bones with meat attached against (cervical vertebrae, two thoracic vertebrae, two ribs), aitch bone, hip a slotted or perforated surface. At the pressures in the machines (~180 bone (one lumbar vertebrae and 4 sacral vertebrae attached), and scap- bar), meat began to flow first, followed by fat and some connective ula. Bones with lean attached were collected before the process to be tissue which left heavy connective tissue and compacted bones within manually knife trimmed. Bones and PTFT were collected 3 times during the chamber (Willemsen, 1994) of recovery. The meat was passed a production shift to serve as 3 replications then shipped within 24h of through a desinewing machine as a final phase. No published data are collection. Upon product arrival, lean was trimmed from the bones available concerning meat from this recovery system. Older versions of using knives. The resulting product was labeled knife trim (KT) and mechanical systems to remove meat from bone involve grinding the was ground twice through a 0.635 cm plate. Fresh, ground (0.635 bone, then forcing the meat through small apertures. Field (1988) and cm), 80% lean pork was manufactured and designated as GP. The Willemsen (1994) noted that composition of meat from mechanical PTFT, KT and GP were randomly sampled, powdered in liquid nitro- recovery could vary based on type of machine, anatomical location of gen and stored 3 mo in double plastic bags at Ϫ80ЊC until analyses. bones, species, temperature and amounts of lean. Proximate, cholesterol, and nonheme iron analyses. Proxi- Meat from mechanical recovery systems has been commonly re- mate analysis was conducted on the KT, PTFT and HT by the fol- ported to have elevated total iron, total pigment, lipid, pH, calcium and lowing AOAC (1990) methods: Moisture (oven-drying), fat (ether cholesterol compared to hand-trimmed meat (Field et al., 1976; Cro- extraction), protein (Kjeldahl), and ash (muffle furnace). Cholester- sland et al., 1995; Demos and Mandigo, 1995). Incorporation of re- ol samples were prepared according to USFDA (1992) procedures covered meat into ground products has reportedly been under 20% of and quantitated by gas chromatography at a commercial laboratory. the formulation to avoid textural and sensory concerns (Miller et al., Nonheme iron was determined according to the method of Rhee and 1986; Demos and Mandigo, 1996a). Ziprin (1987). The USDA (1994) final rule regarding mechanically recovered Total iron and calcium. Analysis for calcium and total iron was meat stated that product derived from AMR could be identified by performed using inductively coupled argon plasma atomic emission species name if bones were not crushed, ground or pulverized and spectrophotometry (ICAP-AES) with an ultrasonic nebulizer (Bra- calcium requirements were met (Ͻ150 mg/100g). Labeling the pro- zelton et al., 1981). Samples (1g) were digested in 5 mL concentrat- duct by species name would provide a marketing advantage for the ed nitric acid with heat, cooled to room temperature and diluted to raw material. The final product from AMR has special attributes and appropriate volumes. Quantification was performed against aqueous acid standards. pH. Duplicate samples (5g) of powdered meat were weighed into Author Calhoun is with Bil Mar Foods, Zeeland, MI. Authors Schnell and beakers with 50 mL of distilled deionized water. After homogenizing Mandigo are with the Dept. of Animal Science, Univ. of Nebraska-Lincoln. for 10s at 10,800 rpm with a Polytron (Brinkman Instruments, New Address inquiries to: A213 Animal Science, Univ. of Nebraska, P.O. Box 830908, Lincoln, NE 68583. York), pH was measured with a general purpose electrode (Corning Glass Works, Corning, NY).

76 JOURNAL OF FOOD SCIENCE—Volume 64, No. 1, 1999 © 1999 Institute of Food Technologists Oxidation-reduction potential. Duplicate samples (5g) of meat were hydroxyproline to total collagen. Collagen values were reported as mg weighed into a Waring Blendor cup with 7.5 mL of 0.1M phosphate collagen/g total sample. buffer (pH 6.0). The blendor cup lid had a hole cut with an attached vacuum hose to minimize oxygen incorporation during the 15s homo- Statistical analysis genation. Sample was transferred to a beaker and measured using a The experimental design was a completely random design with redox combination electrode (Corning Glass Works, Corning, NY) three replications. Data were subjected to analysis of variance utilizing attached to a pH meter. A 2 min equilibration was allowed before the General Linear Models (Proc GLM) procedure of SAS (1990) to reading absolute mV. allowed for stabilization of the value. determine the effect of meat type (PTFT, GP, KT). When a significant Total pigment determination. Total pigment concentration was F-ratio (PϽ0.05) was observed for an effect, means were separated measured by a modified method of Karlsson and Lundstrom (1991). using Fisher’s Protected Least Significant Difference (Steel and Tor- A 5g powdered sample was homogenized with 50 mL of 0.5M phos- rie, 1980). phate buffer adjusted to pH 7.4 and stored overnight at 4ЊC in the dark. Samples were stirred and filtered through Whatman No. 42 paper. The Incorporation into ground pork filtrate (4 mL), 0.4 mL of 10% Triton X-100 detergent solution and Formulation and processing. Lean pork trimmings (93% lean) 0.25 mL of 5M NaOH were mixed. A standard curve of hematin were obtained from pork picnic cushions, previously frozen 3 mo, chloride was prepared and absorbance of all solutions were read at trimmed of all exterior fat and 50% fat pork trimmings from bellies 575 and 700 nm (Gilford Response spectrophotometer, Gilford In- previously frozen 4 mo. Meat was ground (1.27 cm) and randomly struments Laboratories, Oberlin, OH). An equation to regress hematin sampled for fat analysis. The PTFT was obtained from a commercial Ϫ Ϫ Њ concentration on A575 A700 was calculated. The equation was: processor as described, shipped frozen and held at 35 C (~3 mo) until used. PTFT was randomly sampled for fat analysis before for- ϫ Ϫ ϩ Hematin (ppm)=*dilution factor [slope × (A575 A700) intercept] mulation. *dilution factor ϭ 50 mL/5g ϭ 10 Batches of ground pork (11.4 kg) were formulated to contain 10% or 20% fat and 0, 5, 10, or 15% PTFT. Appropriate amounts of raw Hematin (ppm) were converted to mg meat pigment/g tissue (wet wt) materials were mixed 5 min (Model 100DA Food Mixer, Leland with the 0.026 conversion factor of Franke and Solberg (1971). Detroit Mfg. Co., Detroit, MI) then ground through a 0.48 cm plate. Expressible moisture. Expressible moisture was measured in du- Patties weighing 113.4g (11.9 cm dia ϫ 0.95 cm thick) were formed plicate on the meat samples according to a modified method of Jau- using a Hollymatic 580 Patty Machine (Hollymatic Corp., Park For- regui et al. (1981). Two pieces of Whatman #3 filter paper were folded est, IL) with double-wax interleaving paper. Patties (21) were trans- around one piece of VWR Grade 410 filter paper to form a thimble. ferred to plastic foam trays, over-wrapped with polyvinyl chloride The weight of the filter-paper thimble was recorded, 1.5Ϯ0.3g of (PVC) film and stored at 4ЊC under 1184 lux of continuous warm fresh (never frozen) meat sample was added and the thimble placed white fluorescent light for 6 days. Day 0 was the day of manufacture. into 50 mL centrifuge tube to be centrifuged (Sorvall RC 5B, DuPont The remaining patties were packed in double polyethylene bags and Co., Wilmington, DE) at 32,566 ϫ g for 15 min at 4ЊC. The filter frozen at Ϫ35ЊC (Ͻ 2 mo) until further analysis. paper was weighed after removing the meat to determine moisture Cooking measurements. Three frozen patties per treatment/repli- pickup. Expressible moisture was percent of weight lost from the cation were measured for diameter at their 2 widest points and for original sample. thickness at 3 locations 120Њ apart with a micrometer. Frozen patty Fatty acid analysis. Total lipid was extracted from a 5g powdered weight was recorded. Patties were cooked from frozen to 72ЊC inter- sample with 2:1 chloroform-methanol (Bligh and Dyer, 1959). Sam- nal temperature on an electric grill (Model HG4, General Electric, ple extracts were filtered into 250 mL centrifuge bottles, 20 mL of Chicago, IL) at 165ЊC, blotted and weighed. Diameter and thickness water added and centrifuged at 1272 ϫ g for 10 min at 4ЊC. The water- were measured as described and reported as percentage change in methanol layer containing non-lipid components was aspirated and dimensions. Cook loss was expressed as a percentage. residual water removed by adding 10 g of sodium sulfate crystals and Textural analyses. Three patties from each treatment/replication standing 20 min. The remaining chloroform solution was decanted were cooked as described, cooled to room temperature (30 min) and and the solvent removed using a rotary vacuum evaporator. The lipid cut into 6.0 ϫ 6.0 cm squares. Each square was weighed and subject- extract was transferred to a vial for storage under chloroform and ed to the following tests. Peak force (N) and total energy (J) to shear nitrogen gas 24h. a patty were determined using a Lee-Kramer shear cell attached to an Sample extracts were converted to methyl esters according to the Instron equipped with a 2500 kg load cell. A crosshead speed of 100 boron-trifluoride-methanol method outlined by Morrison and Smith mm/min, full scale load of 200 kg and chart speed of 200 mm/min (1964). The methylated samples were analyzed for fatty acid compo- were used. Texture profile analysis was conducted following the pro- sition using a gas chromatograph (Hewlett Packard Model 5840A, cedures developed by Bourne (1978) and Montejano et al. (1985). A Hewlett Packard, Co., Wilmington, DE) equipped with a flame ioniza- square piece of patty was compressed twice to 75% of original height tion detector and a Hewlett Packard 18550A GC integrator (Hewlett using a 14 cm diameter flat plate. A 2500 kg load cell, full scale load of Packard, Co., Wilmington, DE). The samples were separated on 30m 100 kg, chart speed of 500 mm/min, and crosshead speed of 50 mm/ ϫ 0.25 ␮m Carbowax capillary column. The column was operated at min were used. Measurements were calculated for hardness, springi- 140°C for 5 min increasing to 210ЊC at 3ЊC/min and held for 10 min. ness, cohesiveness and chewiness. The injection port was 300ЊC and the detector 350ЊC. The carrier gas Sensory analysis. A sensory acceptance panel comprised of grad- (nitrogen) was under a head pressure of 137.9 kPa with a 100:1 split uate students, faculty, staff and undergraduate students (nϭ40) of the ratio. Identification of fatty acid peaks was made by comparison to the University of Nebraska was utilized to evaluate the pork patties. Pan- retention times of standard fatty acids assayed under identical condi- elists were not screened or trained prior to product evaluation but were tions. Fatty acids were reported as area percent of fatty acids identi- considered experienced since they had participated in previous ground fied. meat evaluations. The attributes of flavor, texture, juiciness, and over- Collagen. A modified method of Bergman and Loxley (1963) was all acceptability were rated on an 8 point hedonic scale where 8 ϭ very followed for quantification of total collagen. After hydrolysis and desirable and 1ϭ very undesirable. Patties were cooked as previously filtration through charcoal, the pH was not adjusted since a stronger described and cut into 2 ϫ 3 cm pieces from the center of each patty. buffer was added to the oxidant solution which eliminated the need for Six samples were randomly chosen for presentation to panelists on titration to raise pH (Eilert et al., 1996). Samples were analyzed in each of 4 days to account for the 24 total treatment/replication combi- duplicate. A factor of 7.25 (Goll et al., 1963) was used to convert nations. Samples were served under red light in individual booths and

Volume 64, No. 1, 1999—JOURNAL OF FOOD SCIENCE 77 Pork from an Advanced Meat Recovery System . . . panelists were provided water to cleanse their pallet between samples. Table 1—Least square means for characterization of pork trim-finely Color. A HunterLab Colorimeter was used to obtain L*, a*, b*, textured (PTFT), knife trimmed meat (KT) and ground pork (GP) and reflectance readings from 400 to 700 nm. Measurements were Attribute PTFT KT GP SEM taken daily for 0 to 6 days of retail storage on randomly selected trays Moisture (%) 65.81 67.01 64.33 0.92 containing 3 patties. Three readings/patty were recorded. The Colo- Fat (%) 18.94 16.19 18.44 1.28 rimeter was equipped with a 30 mm open viewing port and set to Protein (%) 15.38a 17.24ab 18.04b 0.59 Ash (%) 1.14b 0.93a 0.92a 0.05 illuminant A and 2Њ standard observer. The machine was standardized Calcium (mg/100g meat) 107.50c 26.77b 6.12a 5.53 with PVC film covering the white plate to account for film over the Cholesterol (mg/100g meat) 101.67c 72.33b 62.33a 2.49 surface of the patties. Reflectance readings were converted to absor- Total collagen (mg/g meat) 5.34a 12.85b 11.58b 0.49 Ϫ Total iron (mg/100g meat) 3.24b 1.11a 1.20a 0.10 bance [2 log (% reflectance)] and used in the equation of Kryzwicki Nonheme iron (ug/g meat) 5.96b 2.46a 4.07ab 0.68 (1979) to determine percent metmyoglobin. pH 6.39b 6.47b 6.12a 0.03 Oxidation-reduction potential (mV) 147.17a 170.33b 170.62b 4.19 ϭ Ϫ Ϫ Ϫ ϫ Expressible moisture (%) 32.33b 30.46b 27.77a 0.62 Metmyoglobin (%) 1.395 [(A572 A700)/(A525 A700)] 100 Total pigment (mg/g meat) 5.87b 2.41a 2.16a 0.18 Metmyoglobin reducing ability (unitless)0.48 0.51 0.52 0.02 Statistical analyses. The experiment was conducted as a random- a-cMeans within a row with different superscripts are different (P<0.05). ized complete block design replicated 3 times. Analysis of variance utilizing the Proc Mixed procedure of SAS (Littell et al., 1996) was used to test the effects of fat (10% and 20%), PTFT (0, 5, 10, 15%) Table 2—Fatty acid content of pork trim-finely textured (PTFT), knife and day (0, 1, 2, 3, 4, 5, 6; color data only). Significant interaction and trimmed meat (KT) and ground pork (GP) as a percent of total lipid main effect means were compared using Fisher’s Protected LSD (Steel Fatty acid PTFT KT GP SEM and Torrie, 1980). Color data were collected as repeated measure- C14:0 1.82 2.03 1.94 0.16 ments over time. Correlation among repeated measurements was ac- C16:0 25.84 27.15 27.36 1.33 counted for using an AR(1) model selected according to published C16:1 4.38 4.73 3.98 0.40 C18:0 10.26 10.03 10.65 0.48 procedures (Littell et al., 1996). Contrasts were used with the color C18:1 45.15a 42.63b 41.07b 0.76 data to determine linear, quadratic and cubic effects of day. All signif- C18:2 11.39 12.25 13.43 1.29 icance was reported at PϽ0.05. C18:3 0.50 0.64 0.61 0.08 C20:4 0.86 0.79 1.07 0.28 RESULTS & DISCUSSION abMeans within a row with different superscripts are different (P<0.05).

Characterization The PTFT did not differ (PϾ0.05) from KT or GP in moisture or fat. It was similar to KT for protein content (Table 1) which may meat was carcass temperature at time of deboning. indicate minimal incorporation of components of bone soft tissue, The PTFT had a higher (PϾ0.05) calcium content (107.5 mg/ such as hemoglobin, during recovery. The fat content of PTFT (~19%) 100g) than GP or KT (Table 1), but was below the USDA allowable makes it a useful substitute for 20% fat trimmings in meat formula- limit of 150 mg/100g meat (USDA, 1994). Elevated calcium has been tions. Some studies have reported a higher fat content in mechanically reported in mechanically recovered meat (Demos, 1995; Crosland et recovered meat compared to hand trimmed meat (Field et al., 1976; al., 1995) and especially that from early recovery methods which Crosland et al., 1995; Demos and Mandigo, 1995) attributed to in- ground the bone (Field, 1974; Goldstrand, 1975). Crosland et al. creased incorporation of bone marrow. Field (1988) reported the fat (1995) attributed the higher calcium in meat from a hydraulically pow- content of bone marrow from vertebrae could range from 6% to 50%, ered piston-type machine to be due to preparation of the raw material and up to 95% when considering round bones such as femurs. The fat (prebreaking of bones) and to the recovery process which created a content of meat from AMR would likely vary based on specific recov- likelihood for bone fragments. Calcium may also come from calcium ery process, bone type, species, and amount of lean (Field, 1988; phosphate in bone fluids which can be expressed when the bones are Willemsen, 1994). A more important concern than total lipid may be placed under pressure (Crosland et al., 1995). the degree of saturation and the fatty acid profile as they relate to The cholesterol content of the meat sources differed (PϽ0.05; storage stability and nutritional content. Table 1). The higher cholesterol of PTFT may be due to expression of The fatty acid profile of PTFT is important to the stability and adipose cells, incorporation of more cells which contain cholesterol as successful use of the product. Of the 8 fatty acids detected in the meat, a component of cell membranes (Tortora, 1991), or expression of only oleic (C18:1) was found in higher amounts in PTFT (PϽ0.05) immature blood cells from the soft interior of the bone. The effect of than GP or KT (Table 2). Mechanically recovered meat has been cholesterol on a final product would be minimal because meat from shown to have a different fatty acid profile than hand boned meat due AMR is commonly utilized at low levels (Ͻ20%; Miller et al., 1986; to incorporation of bone marrow (Kunsman and Field, 1976) which Demos and Mandigo, 1996a). contains lipids with different characteristics than those in subcutane- The collagen content of PTFT was lower (PϽ0.05; Table 1) than ous fat and muscle (Mello et al., 1976). Kunsman and Field (1976) for GP or KT due to the final phase when the meat passes through a concluded that mechanically recovered red meat had more polyunsat- desinewing machine. Recovered meat from other mechanical systems urated fatty acids than hand-boned meat. However, the recovery meth- has had low collagen (Field et al., 1976; Ockerman et al., 1981) be- od in our study did not grind bone as that used by Kunsman and Field cause mechanical recovery separates bone and collagen from muscle (1976). The lack of difference in fatty acids and polyunsaturates be- (Field et al., 1974; Satterlee, 1975). tween samples may indicate lower incorporation of components of Total iron was higher (PϽ0.05) for PTFT versus GP and KT. bone soft interior. Other researchers have noted elevated total iron in mechanically re- The ash content was higher (PϽ0.05) for PTFT (1.14%) com- covered meat (Field et al., 1976; Crosland et al., 1995; Demos and pared to KT or GP (Table 1). However, when ash content of PTFT Mandigo, 1995). The majority of the iron was heme-iron which could was compared to trimmings removed with a Whizzard® knife (data be determined by difference based on non-heme values (Table 1). The not shown) the values did not differ (1.11% and 1.06%, respectively). nonheme iron is likely in the form of hemosiderin and ferritin which Whizzard® trimming is a more automated system for removing meat are storage forms for iron in the blood. Crosland et al. (1995) indicat- from bones than hand trimming. Field et al. (1974) noted another ed that the pressure exerted on the bones during recovery may force factor that affected ash and calcium content of mechanically deboned the release of iron-containing bone fluids through the porous struc-

78 JOURNAL OF FOOD SCIENCE—Volume 64, No. 1, 1999 tures of the bone (Underwood, 1971). The iron content of PTFT is the AMR process removes connective tissue, there is a concentrating important since, both heme iron and non-heme iron have been impli- effect of remaining components which could contribute to some ele- cated as catalysts in lipid oxidation (Kanner et al., 1987) which may vated values. contribute to reduced shelf stability. The pH of PTFT was similar to KT and both were higher (PϽ0.05; Incorporation into ground pork patties Table 1) than GP (6.12). This did not agree with previous work on The fat contents of the 10% and 20% fat formulations were actual- mechanically recovered meat in which the pH was reported as higher ly 8.62% and 17.88% respectively (Table 3). Moisture, fat, protein than hand-trimmed product (Ockerman, et al., 1981; Demos and Man- and ash did not differ (PϾ0.05) due to PTFT addition so PTFT can be digo, 1995). The high pH had been attributed to bone marrow which added up to 15% without significantly altering proximate composi- has a pH of 6.0–7.0 (Anderson and Gillett, 1974). Field and Arasu tion. (1981) devised a technique to detect bone marrow in mechanically Addition of PTFT did not affect expressible moisture (Table 3) of recovered meat based on pH. Our data did not support the validity of raw patties (PϾ0.05) although PTFT alone displayed greater express- that technique for detecting bone marrow incorporation, since pH of ible moisture than an 80% lean ground pork control (Table 1). When PTFT did not differ from knife- trimmed meat. This may suggest that the ground pork patties were cooked, no differences (PϾ0.05) were meat in closer proximity to the bone is inherently higher in pH. The detected in cook yield, change in patty diameter or change in patty elevated pH typically reported for mechanically recovered meat may thickness for main effects PTFT or fat. Cook yield ranged from 72.69% not be exclusively due to bone marrow incorporation. The buffering to 73.70% for all levels of PTFT addition. When Demos and Mandigo capabilities of meat (PTFT) may also be masking any possible pH (1996a) incorporated mechanically recovered neck bone lean (MRNL) shift caused by incorporation of bone marrow components. into ground patties, expressible moisture changes as MRNL Higher pH did not result in increased expressible moisture as increased were not significant. moisture loss was higher for PTFT and KT vs GP. Higher expressible Texture data showed Kramer shear peak force did not differ moisture of PTFT may be a result of the small particle size and in- (PϾ0.05) due to PTFT or fat level (Table 3). Total energy to shear a creased overall surface area and may offset the moisture retention patty and springiness from compression differed between fat levels effects normally associated with high pH. Most researchers of me- (P<0.05) but were not affected by PTFT (PϾ0.05). Patties containing chanically recovered meat have reported the product to had good wa- 5% or 15% PTFT were softer and less chewy than 0% addition. The ter holding capabilities alone (Demos and Mandigo, 1995) or when patties containing 10% PTFT did not differ from 0%, 5% or 15% incorporated into other products (Arasu et al., 1981; Demos and Man- PTFT treatments for hardness and chewiness (PϾ0.05). Cohesive- digo, 1996a). ness decreased (P<0.05) with addition of PTFT. The oxidation-reduction potential of PTFT was lower (PϽ0.05: Demos and Mandigo (1996a) reported objective texture measure- Table 1) than GP or KT which may be indicative of PTFT having less ments for ground beef patties that suggested levels of MRNL over ability to oxidize myoglobin, thereby contributing to the maintenance 15% created a product that was too soft. In our results, texture rated by of the desirable oxymyoglobin pigment. Demos and Mandigo (1995) a sensory panel was not affected by PTFT or fat. Panelists rated reported hand-trim meat had lower oxidation-reduction potential than juiciness of the product containing any level of PTFT as more desir- mechanically recovered meat which they attributed to less exposed able than 0% addition. Flavor and overall acceptability of patties were surface area. The hypothesized benefit of low oxidation-reduction not affected by fat or PTFT (PϾ0.05). Demos and Mandigo (1996a) potential is that PTFT would contribute to the maintenance of a desir- found addition of 15% MRNL levels in low-fat (10% fat) patties able color when incorporated into other products. resulted in sensory attributes that mimicked 20% fat patties. Miller et Total pigment of PTFT was higher (PϽ0.05) than GP or KT. The al. (1986) concluded that 15% mechanically separated beef (MSB) heme pigment incorporation from the bone soft interior, specifically could be added to ground beef without altering sensory properties or hemoglobin in its oxygenated form (Field, 1988), and the reduction in visual appearance. Up to 45% MSB could be added to ground pork connective tissue (Field, 1975), would contribute to the brighter color before sensory flavor and overall satisfaction began to decrease. They of PTFT. Demos and Mandigo (1995) found total pigment content of reported no differences in sensory juiciness due to addition of up to mechanically recovered meat was greater than hand-deboned meat, 75% MSB which was not supported by our results. but both were lower than bone marrow. Color intensity of mechanical- The lightness (L*) of patties decreased with PTFT addition ly recovered may vary based on anatomical location of the meat (PϽ0.05; Fig. 1). Redness (a*) increased linearly (PϽ0.05; Fig 2a) and animal age (Warriss and Rhodes, 1977; Field et al., 1980). The higher color intensity of mechanically recovered meat may provide a desirable effect in certain products, but could cause concern in light colored products such as white sausage. Some of the differences in PTFT compared to KT are likely attrib- uted to incorporation of components of bone marrow. Bone marrow, as a whole entity, is not incorporated into meat from AMR. Bone marrow is a dynamic organ, comprised of a diverse number of cells at various stages of differentiation (Naeim and Nimer, 1992), which functions to produce new red blood cells (Foucar, 1995). We hypoth- esized it is possible for only components of bone marrow to be ex- tracted from the bone interior during AMR. Prediction of bone mar- row incorporation based on components is erroneous. The compo- nents, such as iron or total pigment, are not incorporated at propor- tional levels and do not represent bone marrow content as a whole organ. Predicition based on components assume a linear relationship between content in the bone marrow and in the final AMR product. We conclude that only components of bone marrow are incorporated into meat from AMR and that the components cannot be used as a predic- tion of bone marrow incorporation into meat. The inherent properties of PTFT do not differ notably from knife- Fig. 1—Least square means of L* (lightness) for ground pork patties trimmed lean pork for most attributes related to functionality. Because stored 6 days under 1076 lux of light at 4°C (P<0.05).

Volume 64, No. 1, 1999—JOURNAL OF FOOD SCIENCE 79 Pork from an Advanced Meat Recovery System . . .

Table 3—Least square means of attributes for ground pork patties containing 2 levels of fat and 4 levels pork trim-finely textured (PTFT)

Fat level PTFT Levels 10% 20% SEM 0% 5% 10% 15% SEMd Fat (%) 8.62 17.88y 0.38 13.21 13.16 13.26 13.35 0.43 Moisture (%) 73.32x 65.89y 0.40 69.40 69.66 69.76 69.6 0.45 Protein (%) 19.10x 17.12y 0.13 17.88 18.34 18.19 18.05 0.19 Ash (%) 1.10x 0.98y 0.02 1.05 1.05 1.01 1.05 0.02 Expressible Moisture (%) 34.77 35.44 0.50 36.49 34.74 34.90 34.25 0.80 Cook yield (%) 73.50 73.07 0.50 72.69 73.48 73.70 73.34 0.73 Change in diameter (%) 20.29 19.69 1.85 18.29 20.62 19.69 21.32 2.31 Change in thickness (%) 8.31 6.94 0.94 6.44 8.48 6.18 9.39 1.41 Kramer peak forcee (N) 1378.43x 1264.13y 63.94 1367.41 1360.32 1289.47 1267.91 76.32 Kramer total energye (J) 31.41x 27.80y 1.63 30.24 30.39 29.54 28.24 1.83 Hardnesse(N/g) 13.12x 11.05y 0.32 13.11a 11.70b 12.40ab 11.14b 0.48 Cohesivenesse (unitless) 0.59x 0.52y 0.02 0.58a 0.55b 0.55b 0.54b 0.02 Springinesse (mm) 22.92x 21.08y 0.22 22.33 21.72 22.11 21.83 0.33 Chewinesse (J/g) 0.17x 0.12y 0.02 0.17a 0.14b 0.15ab 0.13b 0.02 Texture 5.44 5.42 0.11 5.20 5.48 5.66 5.36 0.16 Juiciness 5.13x 5.46y 0.09 4.90a 5.32b 5.54b 5.42b 0.14 Flavor 5.07 5.06 0.09 4.79 5.08 5.28 5.07 0.14 Overall acceptability 5.18 5.24 0.10 4.89 5.28 5.46 5.21 0.15 abcMean values in a row followed by different letters are significantly different (P<0.05). dThe largest SEM’s were reported for fat and PTFT (n=24 for all treatments except 10% fat and 15% PTFT, n=23). eSample size was one patty cut to 6.0 × 6.0 cm. xySignificantly different (P<0.05).

with increased PTFT which could be attributed to the high total pig- detrimental to fresh color of ground beef patties after only 2 days of ment content of PTFT. Over days of storage, redness decreased until retail display. They attributed color changes to microbial growth on day 3, increased until day 5 then remained the same until day 6. the basis of internal and external pH and not plate counts. Microbial Statistically, this was a cubic response (PϽ0.05). Fat differences were growth may influence color but should not be the sole cause of color not significant and PTFT did not influence a* color over time (no deterioration after only three days of retail display. Oxidative changes PTFT × day interaction). of heme pigment may be attributed to bacterial, enzymatic, or lipolytic The b* values (data not shown) as an indication of yellowness causes. Any factor capable of lowering the partial pressure of oxygen were not affected by PTFT or fat level (both PϾ0.05), but responded may accelerate metmyoglobin formation (Saleh and Watts, 1966). cubically (PϽ0.05) during retail storage. Surface metmyoglobin was According to Faustman and Cassens (1990), growth of bacteria on the not affected by fat or PTFT (Fig. 2b) but displayed a cubic response meat surface would affect the oxygen partial pressure due to con- over time (PϽ0.05). Surface metmyoglobin increased through 3 days sumption of oxygen and cause initial oxidation of the meat pigments. of display, then decreased during days 4 through 6 which was the Upon further retail display, further oxygen consumption would create inverse trend of redness. On days 3 and 4, metmyoglobin (%) exceed- a reducing environment for metmyoglobin to form deoxymyoglobin ed 40% which is the level of metmyoglobin that has been associated (Satterlee and Hansmeyer, 1974) which causes meat to have a desir- with consumer rejection (Greene et al., 1971). able color but microbial counts could then be high. The deterioration of color during the first 3 days of storage was in all patties so it could not be attributed to PTFT. Demos and Mandigo CONCLUSIONS (1996b) reported a trend of color deterioration for all patties during the ADDITION OF PTFT INTO GROUND PORK FORMULATIONS ENHANCED first part of retail display then an improvement or leveling after day 7. juiciness and color intensity while softening texture. The PTFT did They suggested that high levels (30% and 45%) of MRNL were not increase low-fat ground pork juiciness or improve texture as hy- pothesized but did not negatively influence any attributes of the final product. Patties containing PTFT responded similar to patties without PTFT over days of storage. Thus, PTFT could be an economical and advantageous replacement for pork trim in ground pork products. REFERENCES Ackroyd, H.B. 1979. MLC Seminar on recovering meat from bones (May 1978), 21. MLC, Bletchley, UK. Cited in Newman, P.B. 1981. The separation of meat from bone— A review of mechanics and the problems. Meat Sci. 5: 171-200. Anderson, J.T. and Gillett, T. 1974. Extractable-emulsifying capacity of hand and mechanically-deboned mutton. J. Food Sci. 39: 1147-1149. AOAC. 1990. Official Methods of Analysis, 15th ed. Assoc. of Official Analytical Chemists, Washington, DC. Arasu, P., Field, R.A., Kruggel, W.G., and Miller, G.J. 1981. Nucleic acid content of bovine bone marrow, muscle, and mechanically deboned beef. J. Food Sci. 46: 1114- 1116. Bergman, I. and Loxley, R. 1963. Two improved and simplified methods for the spec- trophotometric determination of hydroxyproline. Anal. Chem. 35(12): 1961-1965. Bligh, E.G. and Dyer, W.J. 1959. A rapid method for total lipid extraction and purifi- cation. Can. J. Biochem. Phys. 37: 911-917. Bourne, M.C. 1978. Texture profile analysis. Food Technol. 32(7): 62-66, 72. Brazelton, W.E., Meerdink, G.L., Stowe, H.D., and Tonsager, S.R. 1981. Experience with multielement analysis in diagnostic clinical toxicology and nutrition. Proc. Ann. Met. Am. Assoc. Vet. Lab. Diagn. 24: 111-126. Crosland, A.R., Patterson, R.L.S., Higman, R.C., Stewart, C.A., and Hargin, K.D. 1995. Investigation of methods to detect mechanically recovered meat in meat products— I: Chemical composition. Meat Sci. 40: 289-302. Demos, B.P. 1995. Utilization of mechanically recovered neck bone lean as a raw ma- terial in ground beef manufacture. Ph.D. Dissertation, Univ. of Nebraska, Lincoln. Fig. 2—Least square means of a* (redness) (a) and % metmyoglobin Demos, B.P. and Mandigo, R.W. 1995. Composition and chemistry of mechanically (b) for ground pork patties stored 6 days under 1076 lux of light at recovered beef neck-bone lean. J. Food Sci. 60: 576-579. Demos, B.P. and Mandigo, R.W. 1996a. Physical, chemical and organoleptic properties 4°C (P<0.05).

80 JOURNAL OF FOOD SCIENCE—Volume 64, No. 1, 1999 of ground beef patties manufactured with mechanically recovered neck bone lean. J. myoglobin methods). Meat Sci. 29: 17-24. Muscle Foods 7: 175-186. Kryzwicki, K. 1979. Assessment of relative content of myoglobin, oxymyoglobin and Demos, B.P. and Mandigo, R.W. 1996b. Color of fresh, frozen and cooked ground beef metmyoglobin at the surface of beef. Meat Sci. 3: 1-10. patties manufactured with mechanically recovered neck bone lean. Meat Sci. 42(4): Kunsman, J.E. and Field, R. A. 1976. The lipid content of mechanically deboned red 415-429. meats. J. Food Sci. 41: 1439-1441. Eilert, S.J., Mandigo, R.W., and Sumner, S.S. 1996. Phosphate and modified beef con- Littell, R.C., Milliken, G.A., Stroup, W.W., and Wolfinger, R.D. 1996. SAS System for nective tissue effects on reduced fat, high added-water frankfurters. J. Food Sci. 61: Mixed Models, SAS Institute, Inc., Cary, NC. 1006-1011, 1029. Mello, F.C., Jr., Field, R.A., Forenza, S., and Kunsman, J.E. 1976. Lipid characterization Faustman, C. and Cassens, R.G. 1990. The biochemical basis for discoloration in fresh of bovine bone marrow. J. Food Sci. 41: 226-230. meat: A review. J. Muscle Foods 1: 217-243. Miller, M.F., Davis, G.W., Ramsey, C.B., and Irizarry, H. 1986. Acceptability of various Field, R.A. 1974. Mechanically deboned meat. Proc. Meat Industry Res. Conf. 35. Amer. ground beef and pork products extended with mechanically separated beef. J. Food Meat Inst., Washington, DC. Qual. 9: 345-354. Field, R.A. 1975. Recovery of protein from bones by mechanical deboners. Proc. 21st Montejano, J.G., Hamann, D.D., and Lanier, T.C. 1985. Comparison of two instrumental European Meeting of Meat Res. Work., p. 100. Congress Secretariat, Convention methods with sensory texture protein gels. J. Text. Stud. 16: 403-424. Bureau, Main Station, P.O. Box 2700, CH-3001, Berne, Switzerland. Morrison, W.R. and Smith, L.M. 1964. Preparation of fatty acid methyl esters and dim- Field, R.A. 1988. Mechanically separated meat, poultry and fish. Ch. 4 In Edible Meat ethylacetals from lipid with boron fluoride-methanol. J. Lipid Res. 5: 600-608. By-Products: Advances in Meat Research Vol. 5, A.M. Pearson and T.R. Dutson(Ed.), Naeim, F. and Nimer, S. 1992. Bone marrow structure and function. Ch. 1, In Pathology p. 83-126. Elsevier Science Publishing Co., Inc., New York. of Bone Marrow, p. 1-31. Igaku-Shoin Medical Publishers, Inc. New York. Field, R.A. and Arasu, P. 1981. A simple method of estimating amount of red marrow Ockerman, H.W., Houben, J.H., Krol, B., Plimpton, R.F., and Schad, M. 1981. Effect of present in mechanically deboned meat. J. Food Sci. 46: 1622-1623. bone source and storage on the role of mechanically deboned pork in rancidity Field, R.A., Kruggel, W.G., and Riley, M.L. 1976. Characteristics of mechanically recov- development in a cooked and smoked sausage. J. Food Sci. 46: 220-226. ered lean hand separated meat and bone residue from bones destined for rendering. Rhee, K.S. and Ziprin, Y. A. 1987. Modification of the Schricker nonheme iron method J. Anim. Sci. 43: 755-762. to minimize pigment effects for red meats. J. Food Sci. 52: 1174-1176. Field, R. A., Riley, M.L., and Corbridge, M.H. 1974. Influence of yield on calcium Saleh, B. and Watts, B.M. 1966 . Substrates and intermediates in the enzymatic reduc- content of mechanically deboned lamb and mutton. J. Food Sci. 39: 285-287. tion of metmyoglobin in ground beef. J. Food Sci. 33: 353-357. Field, R.A., Sanchez, L.R., Kunsman, J.E., and Kruggel, W.G. 1980. Heme pigment con- SAS. 1990. SAS® Language and Procedures, Version 6, First Edition. SAS Inst., Inc., tent of bovine hemopoietic marrow and muscle. J. Food Sci. 45: 1109-1112. Cary, NC. Foucar, K. 1995. Hematopoiesis. Ch. 1 In Bone Marrow Pathology, 1-12. ASCP Press, Satterlee, L.D. 1975. Improving utilization of animal by-products for human foods - Chicago, IL. A review. J. Anim. Sci. 41: 687-697. Franke, W.C. and Solberg, M. 1971. Quantitative determination of metmyoglobin and Satterlee, L.D. and Hansmeyer, W. 1974. The role of light and surface bacteria in the total pigment in an intact meat sample using reflectance spectrophotometry. J. Food color stability of prepackaged beef. J. Food Sci. 39: 305-308. Sci. 36: 515-519. Steel, R.G.D. and Torrie, J.H. 1980. Principles and Procedures of Statistics, 2nd Ed., Froning, G.W. and Johnson, F. 1973. Improving the quality of mechanically deboned McGraw-Hill Book Co., New York. fowl meat by centrifugation. J. Food Sci. 38: 279-281. Tortora, G.J. 1991. Cells. Ch. 3, In Introduction to the Human Body, The Essentials of Goldstrand, R.E. 1975. Mechanically deboned meats-yield and product characteris- Anatomy and Physiology, p. 35-43. Harper Collins Publishers, New York. tics. Proc. 28th Recip. Meat Conf., p. 116-126. Amer. Meat Sci. Assn., Chicago, IL. Underwood, E.J. 1971. Trace Elements in Human and Animal Nutrition, 3rd ed. Aca- Goll, D.E., Bray, R.W., and Huekstra, W.G. 1963. Age associated changes in muscle demic Press, New York. composition. The isolation and properties of collagenous residue from bovine USDA. 1994. Meat produced by advanced meat/bone separation machinery and meat muscle. J. Food Sci. 28: 503-509. recovery systems. Fed. Reg. 59: 62551-62664. Greene, B.A., Hsin, I.M., and Zipser, M.W. 1971. Retardation of oxidative color changes USFDA. 1992. Methodology appropriate for fatty-acid cholesterol analysis. Lipid in raw ground beef. J. Food Sci. 36: 940-942. Manual. U.S. Food & Drug Administration. Jauregui, C.A., Regenstein, J.M., and Baker, J.R.C. 1981. A simple centrifugal method Warriss, P.D. and Rhodes, D.N. 1977. Hemoglobin concentrations in beef. J. Sci. Food for measuring expressible moisture, a water-binding property of muscle foods. J. Agric. 28: 931-934. Food Sci. 46: 1271, 1273. Willemsen, B.J.J. 1994. Separation of residual meat attached to bones. Proc. 47th Recip. Kanner, J., German, J.B., and Kinsella, J.E. 1987. Initiation of lipid peroxidation in Meat Conf., p. 39-43. Amer. Meat Sci. Assn., Chicago, IL. biological systems. Crit. Rev. Food Sci. Nutr. 25: 317-364. Ms received 12/23/97; revised 6/15/98; accepted 8/16/98. Karlsson, A. and Lundstrom, K. 1991. Meat pigment determination by a simple and non-toxic alkaline haematin method—(an alternative to Hornsey and the cyanomet- Published as paper number 12116, Journal Series, Nebraska Agricultural Research Division.

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