Control of Clostridium perfringens germination and outgrowth by buffered sodium citrate during chilling of roast beef and injected pork.

Inhibition of the germination and outgrowth of Clostridium perfringens by buffered sodium citrate (Ional) and buffered sodium citrate supplemented with sodium diacetate (Ional Plus) during the abusive chilling of roast beef and injected pork was evaluated. Beef top rounds or pork loins were injected with a brine containing NaCl, potato starch, and potassium tetrapyrophosphate to yield final in-product concentrations of 0.85, 0.25, and 0.20%, respectively. Products were ground and mixed with Ional or Ional Plus at 0, 0.5, 1.0, and 2.0%. Each product was mixed with a three-strain C. perfringens spore cocktail to obtain final spore concentrations of ca. 2.5 log10 spores per g. Chilling of roast beef from 54.4 to 7.2 degrees C resulted in C. perfringens population increases of 1.51 and 5.27 log10 CFU/g for 18- and 21-h exponential chill rates, respectively, while chilling of injected pork resulted in increases of 3.70 and 4.41 log10 CFU/g. The incorporation of Ional into the roast beef formulation resulted in C. perfringens population reductions of 0.98, 1.87, and 2.47 log10 CFU/g with 0.5, 1.0, and 2.0% Ional, respectively, over 18 h of chilling, while > or = 1.0% Ional Plus was required to achieve similar reductions (reductions of 0.91 and 2.07 log10 CFU/g were obtained with 1.0 and 2.0% Ional Plus, respectively). An Ional or Ional Plus concentration of > or = 1.0% was required to reduce C. perfringens populations in roast beef or injected pork chilled from 54.4 to 7.2 degrees C in 21 h. Cooling times for roast beef or injected pork products after heat processing can be extended to 21 h through the incorporation of > or = 1.0% Ional or Ional Plus into the formulation to reduce the potential risk of C. perfringens germination and outgrowth.

The real story about food safety.

Students should be thoroughly aware of the safety issues that affect the food industry and we should be prepared to summarize the issues in our classes. Food safety covers areas including nutrition, chemical residues, physical contaminants, and food-borne diseases. The real and perceived issues relating to each of these areas are summarized along with thoughts of how to address those issues. The information could be used to initiate classroom discussions about food safety and enhance understanding.

Effects of steam-flaked sorghum grain or corn and supplemental fat on feedlot performance, carcass traits, longissimus composition, and sensory properties of steers.

One hundred forty British x Exotic crossbred, yearling steers (370 kg) were used in a 2 x 2 factorial experiment to evaluate main effects and the interaction of grain type (steam-flaked sorghum grain [SFSG] or steam-flaked corn [SFC]) and level of supplemental far (0 or 4% yellow grease [YG]) on feedlot performance, diet NE concentration, carcass traits, and chemical composition and sensory properties of longissimus muscle. Steer performance and estimated dietary NEm and NEg values were not different between SFSG and SFC. Supplemental YG improved (P less than or equal to .05) gain/feed and estimated NEm and NEg of both SFSG and SFC diets. Compared with steers fed SFSG, steers fed SFC had a more yellow (P less than .05) subcutaneous fat color. Supplemental YG had an additive effect (P less than .025) on yellow color of subcutaneous fat but improved (P less than .08) the lean color of longissimus muscle. Grain type or supplemental YG had no effect on sensory properties or mechanical shear of longissimus muscle. Longissimus muscle cholesterol content was elevated (P less than .05) by supplemental YG (.49 vs .52 mg/g of wet tissue for 0 vs 4% YG, respectively); however, the biological significance of this result is questionable. Similarly, effects of YG on increased (P less than .05) stearic acid concentration and a higher concentration (P less than .05) of linoleic acid measured in longissimus muscle of steers fed SFSG vs SFC were small in magnitude. These data indicate that under the conditions of this experiment, NE contents of SFSG and SFC were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Chilling and cooking rate effects on some myofibrillar determinants of tenderness of beef.

Our objectives were to examine the effects of prerigor excision and rapid chilling vs. conventional carcass chilling of two muscles on proteolysis and tenderness during the postmortem storage, as well as the effects of fast and slow rates of cooking on myofibrillar characteristics and tenderness. The longissimus thoracis (LT) and triceps brachii (TB), long head muscles were removed 45 min after exsanguination from the left side of 12 carcasses and chilled in an ice bath to induce cold shortening (excised, rapidly chilled). At 24 h postmortem, the corresponding muscles were removed from the right side (conventionally chilled). All muscles were cut into 2.54-cm-thick steaks and assigned to one of two postmortem times (1 or 14 d), and to raw and cooking treatments. Steaks were cooked at 260 degrees C (FAST) or 93 degrees C (SLOW) in a forced-air convection oven to an internal temperature of 70 degrees C. Cooking loss, cooking time, and Warner-Bratzler shear force (WBSF) were measured on cooked steaks. Sarcomere length (SL) and the extent of proteolysis of desmin were measured on raw and cooked steaks. As expected, the excised, rapidly chilled muscles had a much more rapid (P < 0.05) temperature decline than those that were conventionally chilled. The excised, rapidly chilled treatment resulted in shorter (P < 0.05) SL, and SL was shorter (P < 0.05) in LT than in TB steaks. Raw steaks had longer (P < 0.05) SL than cooked steaks, regardless of chilling treatment. The FAST cooking resulted in shorter (P < 0.05) SL than SLOW cooking in conventionally chilled steaks, but cooking rate had no effect (P > 0.05) on SL of rapidly chilled steaks. Generally, TB steaks required longer (P < 0.05) cooking times and had higher (P < 0.05) cooking losses than LT steaks, and FAST-cooked steaks had greater (P < 0.05) cooking losses than SLOW-cooked steaks. Rapidly chilled steaks had less (P < 0.05) degradation of desmin than conventionally chilled steaks (31 vs. 41%). Aging for 14 d increased (P < 0.05) desmin degradation. Rapid chilling of muscles resulted in much higher (P < 0.05) WBSF values, whereas aging resulted in lower (P < 0.05) WBSF values. The SLOW-cooked TB steaks were more tender (P < 0.05) than FAST-cooked TB steaks and LT steaks cooked at either rate. Excised, rapidly chilled muscles underwent proteolysis, but it occurred at a slower rate during the first 24 h postmortem than it did in conventionally chilled muscles. Cooking rate did not affect tenderness of LT steaks, but SLOW cooking resulted in more tender TB steaks.

Effects of enhancing beef longissimus with phosphate plus salt, or calcium lactate plus non-phosphate water binders plus rosemary extract.

Beef strip loins (n=36) were enhanced with a sodium phosphate plus salt solution (PS); or with a calcium lactate solution (Ca) plus 1% or 2% beef broth (Br) plus natural flavoring (N) containing rosemary extract; or with 1% or 2% kappa carrageenan (Cr) plus N to determine effects of ingredients on color life, water-binding ability, and palatability traits. Enhancement with PS resulted in higher pH, higher pumped yields, greater water-binding ability, and higher tenderness and juiciness scores than enhancement with Ca (all p<0.05). Enhancement with Ca resulted in less color deterioration, less metmyoglobin discoloration, higher L (∗), a (∗), and b (∗) values, higher beef flavor intensity scores and lower off-flavor scores than enhancement with PS (all p<0.05). Warner-Bratzler shear values did not differ among treatments. Steaks enhanced with Br had less color deterioration, less metmyoglobin discoloration, and higher L (∗) values than those enhanced with Cr (all p<0.05). Pumped yields were not different between loins enhanced with Br or Cr. The N flavoring containing rosemary extract decreased (p<0.05) discoloration. Enhancing beef longissimus with PS increased water-binding capacity and sensory tenderness traits, but reduced color stability and increased off-flavors, whereas Ca preserved color stability and enhanced flavor at the expense of pumped yields. The use of Br or Cr had no influence on tenderness or palatability traits.

Effects of low-voltage electrical stimulation during exsanguination on meat quality and display colour stability.

Five steers from each of four slaughter groups were randomly assigned to a low-voltage electrical stimulation (LVES) treatment during exsanguination (within 5 min after stunning) and five served as controls (C). LVES consisted of 50V of 60 Hz alternating current (1 s on and 1 s off for 2 min). At 28 h, LVES longissimus (LM) was lighter in colour, softer, coarser in texture and tended to have lower marbling estimates than C. LVES LM steaks were lighter red at 0 and 1 days, but more discoloured at 5 days, of display than C steaks. Both the deep (DSM) and superficial (SSM) portions of LVES semimembranosus (SM) steaks were lighter red at 0 and 1 days of display than C steaks. Water-holding capacity for LVES LM and DSM steaks was lower than for C steaks. A trained sensory panel found LVES LM steaks to be less juicy and less tender than C steaks. Also, LVES LM steaks had greater cooking losses than C steaks in two of the four slaughter groups. We conclude that LVES during exsanguination, coupled with relatively slow initial chilling, may be detrimental to muscle quality.

Effects of calcium salts on beef longissimus quality.

The objective of this research was to evaluate the effects of injection marination with calcium salts on beef longissimus quality traits. Strip loins were injected (11% by weight) with distilled water or a 0.1, 0.2, or 0.3 M solution of calcium ascorbate, calcium chloride, or calcium lactate. Non-injected loins served as controls. Visual and instrumental color evaluations indicated that calcium ascorbate accelerated myoglobin oxidation, and increasing molar concentration of any calcium salt caused faster (P<0.05) discoloration. Aerobic microbial plate counts were lower (P<0.05) for treatments containing calcium lactate than those with calcium chloride or calcium ascorbate. Calcium ascorbate inhibited lipid oxidation whereas calcium lactate and calcium chloride appeared to be pro-oxidants of lipid oxidation. No differences for Warner-Bratzler shear force or sensory panel tenderness were found among the calcium salts; however, 0.3 M treatments had lower shear values and were judged more tender than 0.1 M treatments. Calcium ascorbate and calcium chloride treatments resulted in less (P<0.05) beef flavor and more (P<0.05) off-flavors than calcium lactate treatments. In addition, 0.1 M treatments had higher (P<0.05) beef flavor scores while 0.3 M treatments had higher (P<0.05) off-flavor scores. Considering the effects on color life, microbial inhibition, shear force, and sensory traits, we recommend injecting beef longissimus with a 0.1 M solution of calcium lactate to enhance both uncooked and cooked quality.

Staged injection marination with calcium lactate, phosphate and salt may improve beef water-binding ability and palatability traits.

Semitendinosus and longissimus muscles from USDA Select carcasses were used to investigate the effects of staged injection of calcium lactate followed by phosphate and salt (PS) on water-binding ability and palatability traits. Calcium lactate (0.2 M) and PS (8.4% and 4.2%, respectively) were sequentially injected (5.5% by weight) into muscles with 0, 1, 3, or 5 h holding time between injections. Treatments also included a double pump of 0.1 M calcium lactate with 0 h holding time between injections and a non-marinated control. Injection of calcium lactate and PS increased (P<0.05) pumped yield and decreased (P<0.05) expressible moisture values compared to calcium lactate injection only. No differences in peak force, total energy, or myofibrillar fragmentation index were observed among marination treatments for either muscle; however, longissimus tenderness was unusually high. Trained-panel evaluation of sensory traits did not differ for the semitendinosus muscle. Staged injection of calcium lactate and PS improved (P<0.05) myofibrillar and overall sensory tenderness scores of longissimus muscle over those of the non-marinated control. However, beef flavor intensity scores were lowered (P<0.05) by addition of PS. Holding time between injections did not appear to consistently influence water-binding ability or palatability traits. These data suggest that separate solutions of calcium lactate and PS may be injected into longissimus muscle to improve water-binding ability and palatability traits.

Sensory evaluation of beef-flavor-intensity, tenderness, and juiciness among major muscles.

Twelve muscles from eight USDA Select/Choice grade steers were evaluated for beef-flavor intensity, tenderness, and juiciness. The biceps femoris, psoas major, gluteus medius, semimembranosus, and triceps brachii were similar in beef-flavor-intensity (P > 0·05) and were ranked as the most intensely flavored of all muscles. The rectus femoris, longissimus lumborum, serratus ventralis, infraspinatus, semitendinosus, pectoralis profundus, and supraspinatus generally were less intense in beef-flavor than the other muscles and were ranked from highest to lowest intensity in that order. The psoas major was the most tender (P > 0·05) followed by the infraspinatus, longissimus lumborum, and rectus femoris, which were similar (P > 0·05). Generally, muscles from the chuck and loin were juicier than those from the round.

Comparisons of the effect of electrical stimulation methods on postmortem pH decline in beef muscle.

Results of four electrical stimulation (ES) studies were summarized to demonstrate the impact of different ES parameters on pH decline patterns in postmortem M. longissimus thoracis et lumborum. Postmortem pH decline was modeled as a non-linear function of time, and estimates of minimum obtainable pH, pH decline rates, and time to reach pH 6·0 were compared for each study. The decline model for study 4 (AC, 60 Hz, 50 V; 5 min post mortem) had a larger (P < 0·05) estimate for decline rate than that for study 1 (AC, 60 Hz, 400 V; 1 h post mortem) and the control (non-stimulated) data. The model estimate of time to pH 6·0 (0·56 h) for study 4 was the shortest (P < 0·05) for all treatments. Different ES parameters produce different pH decline patterns post mortem and, therefore, may impact product quality and fabrication and chilling protocols adopted in fresh beef processing.

Frozen beef contamination after exposure to low levels of ammonia gas.

Regulations and publications about food contaminated during ammonia refrigerant leaks provide limited information and recommendations, which means that contaminated products are often held for an indeterminate period or condemned. Moreover, the scientific literature offers little guidance on disposing of products exposed to low levels of ammonia refrigerant gas. We evaluated meat contaminated with low levels of ammonia under frozen storage conditions. Fresh beef semitendinosus muscles were trimmed of external fat; fabricated into 10 x 5 x 2.3 cm (height x width x depth) steaks; and exposed to 50, 100, 250, and 500 ppm ammonia gas (85 mL/min) in a plexiglass enclosure contained in a freezer for 6, 12, 24, and 48 h at -17 +/- 3 degrees C. Ammonia content in meat was analyzed by the indophenol method, and pH was measured according to AOAC official method 981.12. Ammonia levels and pH values increased significantly (P < 0.05) in the exposed meat with increasing exposure times and ammonia concentrations. Ammonia levels were 34.2, 51.5, 81.1, and 116 ppm, and pH values ranged from 5.56 to 5.75 (control range 5.31 to 5.43) when the meat was exposed to 50, 100, 250, 500 ppm for 48 h. Our results showed that meat ammonia content was low even with ammonia exposures as high as 500 ppm at freezing temperatures.

Principles and Practices of Modern Meat Technology 1.

Technological advances offer considerable potential for the meat industry, and many of these advances may directly influence the microbiological characteristics of meat and meat products. Current and potential industry practices are summarized in light of their impact on not only the microbiological and sensory qualitites of meat and meat products, but also processing efficiencies. Microbiological implications of various technologies are emphasized in an effort to indicate some criticial control points that should be understood if the industry is to realize the full potential of those technologies.

Effects of Hot Boning and Various Levels of Salt and Phosphate on Microbial, TBA, and pH Values of Preblended Pork during Cooler Storage.

Five pork carcasses were used to determine the effects of hot boning and various combinations of salt (0, 1.5 or 3.0%) and a phosphate mixture (0 or 0.5%) on microbial, TBA and pH values of preblended pork (preblends). In both HB (hot boned within 2 h postmortem) and CB (conventionally boned at 24 h postmortem) preblends, salt increased (P<0.05) TBA values and decreased (P<0.05) psychrotrophic counts, whereas phosphate increased (P<0.05) pH and decreased TBA values. Salt level could be reduced from 3.0 to 1.5% in preblends without any storage problems if phosphate (0.5%) was included. Phosphate (mixture pH 7.2) seemed to have little influence on microbial growth of preblends during cooler storage.

Effects of Hot Boning and Various Levels of Salt and Phosphate on Protein Solubility, Functionality, and Storage Characteristics of Preblended Pork Used in Frankfurters.

Five pork carcasses were used to determine the effects of hot boning and various combinations of salt (0, 1.5 or 3.0%) and a phosphate mixture (0 or 0.5%) on functional, processing, and storage characteristics of preblended pork (preblends). Although hot-boned (HB) preblends had superior functionalities compared to conventionally boned (CB) preblends, HB and CB frankfurters showed similar processing characteristics. More myosin heavy chain (MHC) from the myofibrillar protein fraction and more actin (P<0.05) from the sarcoplasmic protein fraction were extracted from HB than CB preblends. Addition of salt (1.5 or 3.0%) or phosphate (0.5%) generally increased the extraction of MHC and actin from the myofibrillar protein fraction in both HB and CB preblends. Salt level could be reduced from 3.0 to 1.5% in frankfurters without any processing or storage difficulties, if phosphate (0.5%) was added. Some model system measurements may be used to predict relative processing yield of raw materials.

Inhibition of Listeria monocytogenes and Escherichia coli O157:H7 on Beef by Application of Organic Acids †.

Lean beef surfaces were inoculated with Escherichia coli O157:H7 and Listeria monocytogenes and then sanitized with fumaric, acetic, or lactic acid alone and in combined solutions of those acids at 55°C for 5 s. The initial inoculum level was 8.62 log CFU/cm2 and 5.13 log CFU/cm2 for L. monocytogenes and E. coli O157:H7, respectively. Fumaric acid at a concentration of 1% was the most effective acid in reducing the populations of L. monocytogenes by up to 1 log unit and E. coli O157:H7 by up to 1.3 log units when compared with acetic or lactic acids. The rank order of acids tested against the growth of L. monocytogenes and E. coli O157:H7 was fumaric acid followed by lactic and acetic acids. Fumaric acid at concentrations of 1.0% and 1.5% was more effective than any of the combined solutions of acids.

Reduction of Bacterial Populations on Vacuum-Packaged Ground Beef Patties with Fumaric and Lactic Acids.

The effects of fumaric and lactic acid on the total numbers of aerobic, psychrotrophic, and coliform bacteria on vacuum-packaged ground beef patties at 0, 1, 3, 5, 7, 10, and 14 days of storage at 4°C were studied. Fumaric acid treatments resulted in greater reductions in microbial growth than lactic acid treatments. When 5.0% fumaric acid was used, the lag phase was prolonged and microbial growth was reduced (P < 0.05), with total aerobic, psychotrotrophic, and coliform populations reaching net maximum growths of only 1.46, 1.44, and 0.98 log units, respectively, after storage at 4°C for 10 days. Increasing the acid concentrations significantly decreased the growth of all microorganisms. The 5.0% lactic acid was the most inhibitory against coliforms, resulting in a 3.88-1og unit reduction after 10 days of storage.

Nutritional Regime, Post-Slaughter Conditioning Temperature, and Vacuum Packaging Effects on Bacteriology of Beef Carcasses and Retail Meat Cuts 1.

Thirty-eight crossbred steers were used to evaluate effects of nutritional regime (grass-, short-, long-, and forage-fed) and post-slaughter chilling (3 C) and conditioning temperature (13 C) on carcass psychrotrophic and mesophilic bacterial counts. Inside chucks from right halves of carcasses chilled at 3 C for 48 h were used to evaluate effects of nutritional regime and vacuum packaging on total aerobic and anaerobic bacterial counts. Psychrotrophic and mesophilic mean bacterial counts tended to decrease from 1 to 46 h postmortem regardless of temperature treatment. At 46 h postmortem, the forage-fed group mean psychrotrophic count was significantly lower (P < 0.05) than that for any of the other feeding regimes. Mesophilic mean counts were significantly different (P < 0.05) at 46 h postmortem (grass-fed >short-fed >long-fed > forage-fed). Carcass halves chilled at 3 C for 46 h had lower total psychrotrophic and mesophilic mean bacterial counts than did corresponding halves conditioned at 13 C for 8 h then chilled at 3 C for 38 h. Total aerobic and anaerobic counts tended to remain constant or decrease slightly during vacuum storage for 21 days at 0 to 1 C. Both aerobic and anaerobic counts on vacuum-stored cuts from carcasses of grass-fed steers were significantly higher (P < 0.05) than other feeding-regime means. Aerobic and anaerobic counts on vacuum-stored cuts from carcasses of short-, long-, and forage-fed steers were statistically similar. All carcass and inside-chuck bacterial counts were well within acceptable limits. Scalpel-template sampling was considered to be a significant improvement over previously used methods.

Microbiology of fresh and restructured lamb meat: a review.

Microbiology of meats has been a subject of great concern in food science and public health in recent years. Although many articles have been devoted to the microbiology of beef, pork, and poultry meats, much less has been written about microbiology of lamb meat and even less on restructured lamb meat. This article presents data on microbiology and shelf-life of fresh lamb meat; restructured meat products, restructured lamb meat products, bacteriology of restructured meat products, and important foodborne pathogens such as Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in meats and lamb meats. Also, the potential use of sodium and potassium lactates to control foodborne pathogens in meats and restructured lamb meat is reviewed This article should be of interest to all meat scientists, food scientists, and public health microbiologists who are concerned with the safety of meats in general and lamb meat in particular.

Hot-Fat Trimming Effects on the Microbiological Quality of Beef Carcasses and Subprimals.

Subcutaneous and kidney-pelvic-heart fat were trimmed from one side of each beef carcass (n = 9) immediately after cold water washing. Both sides were sampled for aerobic plate counts (APCs) before being moved to the chill room (0 h) and after 72 h of cold storage. The mean APCs (log10 colony-forming units (CFU)/cm2) of trimmed (HFT) sides at 0 or 72 h were not different (P > 0.05) from those of the nontrimmed (NFT) sides. All sides at 72 h had reduced microbial counts compared to 0 h. By 72 h, HFT sides had numerically lower counts than NFT sides, indicating that the microbial reduction effect of the chill temperature may have been greater on fat-trimmed carcasses than on nontrimmed carcasses. Subprimals from HFT and NFT sides that were trimmed to 0.64-cm fat thickness were microbiologically analyzed before (0 days) and after (14 days) vacuum storage. APCs of all subprimals were slightly reduced after 14 d; however, no difference (P > 0.05) occurred in treatment effect. The mean APC was higher for HFT-side subprimals than for NFT-side subprimals at both 0 and 14 days. This difference probably was due to the fat trimming required for NFT-side subprimals at day 0 as compared to minimal or no trimming of HFT-side subprimals. Those HFT subprimals which were not subsequently trimmed may have picked up additional microorganisms from contact surfaces during fabrication. Based on our trimming protocol, although HFT did not show any negative impact on the microbial quality of carcasses, the higher APC of HFT-side subprimals indicated that extensive trimming may not be effective in improving the microbial quality of meat.

Microbiological Quality of Beef Carcasses and Vacuum-Packaged Subprimals: Process Intervention during Slaughter and Fabrication.

Beef carcass sides (n = 9 per replicate) were sprayed with water (W), 200 ppm chlorine ©, or 3% (vol/vol) lactic acid (L) immediately after rail inspection and at the end of an 8-h spray-chill cycle, resulting in a total of nine different spray combinations. All treatment combinations involving chlorine and/or lactic acid reduced carcass contamination. The reductions in mean log10 CFU/cm2 for carcass aerobic plate count (APC) data ranged from 0.4 to 1.8. The treatment combination using lactic acid at both spray times (L+L) resulted in the greatest reduction. Additionally, treatment combinations involving lactic acid at either time and in combination with water or chlorine tended to reduce APCs more than those treatment combinations without acid. Browning of blood splashes was observed on carcasses sprayed with lactic acid and persisted until fabrication at 72 h postmortem. A companion study was designed, in conjunction with the carcass decontamination study, to evaluate effect of carcass treatment on the microbiological quality of subprimal subdivisions derived from treated carcasses. A facet of the subprimal study evaluated chlorine spray (200 ppm) and microwave radiation as approaches to improving subprimal shelf life and safety. Cuts taken from sprayed carcasses were vacuum packaged with or without intervention treatments, stored at 1 to 2°C and evaluated for both APC and pathogen populations at specified intervals of up to 120 days. These results demonstrated that neither carcass nor intervention treatment had any significant (P > 0.05), beneficial effect on the microbiological quality of subprimal cuts.