Beef Surfaces Research Articles

Efficacy of orange terpene against Escherichia coli biofilm on beef and food contact surfaces

Foodborne pathogen Escherichia coli frequently causes foodborne infections. In our study, we investigated the antibiofilm activity of orange terpene (OT) against E. coli biofilms on a food surface (beef) and different surfaces that come into touch with food, including stainless steel (SS), polyethylene terephthalate (PET), low-density polyethylene (LDPE), and rubber (SR). The study findings revealed that OT significantly (P < 0.05) eliminated 48-h-old biofilms from all food contact surfaces (SS: 2.09 log CFU/cm2, PET: 1.95 log CFU/cm2, LDPE: 1.94 log CFU/cm2, and SR: 1.4 log CFU/cm2). Additionally, on beef surfaces, OT at a minimum inhibitory concentration (MIC) of 0.13 % demonstrated the ability to inhibit biofilm development by approximately 1.5 log CFU/cm2 and reduced pre-formed biofilms by 2.02 log CFU/cm2. Our sensory evaluations showed that it had no adverse impacts on beef color and texture, although it slightly altered the natural odor of beef. Quantitative and qualitative assessments showed that OT has strong bactericidal actions on biofilm populations. It significantly altered cell surface hydrophobicity, reduced cellular ATP levels, and inhibited cell auto-aggregation in planktonic cells (P < 0.05). As a result, our findings emphasize the antibacterial potentiality of OT in reducing the biofilm of E. coli in the food sector.

Myoglobin redox form prediction in fresh beef using computer vision systems and artificial intelligence

To development a computer vision system (CVS) to determine the myoglobin redox forms on beef surfaces, the reflectance spectra of reference samples of deoxymyoglobin (DMb), oxymyoglobin (OMb), and metmyoglobin (MMb) were recorded, and the surface images captured by a digital camera (CVScam) and a cell phone camera (CVScel) to train the algorithm. Meat color changes during blooming and display storage were also recorded. Higher k-fold accuracy was observed for CVScam (90.98 %) than for CVScel (86.53 %), with significantly correlation with colorimeter for OMb (r = 0.77 and 0.71), DMb (r = 0.84 and 0.71), and MMb (r = 0.87 and 0.88). The CVS MMb was lower and the OMb was higher than colorimeter, but the redox form behaviors were more consistent with the expected chemical changes on the surface. The constructed CVS showed satisfactory performance as a useful and accurate tool for predicting the myoglobin redox forms on the beef surface.

Effective Decontamination Methods for Shiga Toxin-producing Escherichia coli on Beef Surfaces for Application in Beef Carcass Hygiene

Effective methods for decontamination of Shiga toxin-producing Escherichia coli (STEC) on beef were evaluated by 48 mL spraying, 100 mL, and 500 mL flushing with ethanol, hydrogen peroxide, peracetic acid, acidified sodium chlorite, and sodium hypochlorite in this study. The flushing with 500 mL of 1,000 ppm peracetic acid was most effective, reducing pathogens by 2.8 log CFU/cm2, followed by 1,200 ppm acidified sodium chlorite. The spraying with 1,000 ppm peracetic acid reduced pathogens by 1.6 log CFU/cm2. The flushing with 500 mL of 200 and 500 ppm acidified sodium chlorite, and 50, 100, 200, and 500 ppm peracetic acid significantly reduced the STEC population compared with those treated with distilled water (p < 0.05), reducing pathogens by 2.1, 2.4, 1.6, 1.8, 2.1 and 2.4 log CFU/cm2, respectively. Additionally, the flushing with 500 mL of 200 and 500 ppm acidified sodium chlorite significantly changed the color of beef samples (p < 0.05), whereas 100–500 ppm peracetic acid did not significantly change the color (p > 0.05). The flushing with 500 mL of 200 and 500 ppm acidified sodium chlorite and 200 and 500 ppm peracetic acid significantly changed the odor of beef samples compared with those treated with distilled water (p < 0.05). There was no difference in the reduction of STEC population between peracetic acid treatment at 25 °C and 55 °C, with or without washing with sterilized distilled water after decontamination. Washing with distilled water after flushing with peracetic acid tended to reduce the odor of the samples. These results suggest that treatment with 100, 200, and 500 ppm peracetic acid, followed by washing with distilled water, might reduce the STEC population without retaining the odor of the sanitizer.

Chitosan-puerarin composite hydrogel with magnetic enhanced photothermal properties as sustained antimicrobial coatings for beef preservation

The bactericidal properties of traditional food coatings mostly depend on the amount of fungicides present, which reduces the sustainability of food packaging. Herein, we proposed a magnetic field to precisely modulate the near-infrared (NIR) absorption activity to enhance antimicrobial coatings sustainability. Inspired by the typical grinding procedure, the assembly of CP/Fe3O4@TA nanofiber hydrogel was proposed as the coating, applying mechanical force and encouraging the collision of effective molecules of puerarin (PUE), chitosan (CS), and Fe3O4@TA NFs. This hydrogel design offers precise control over the physical and chemical properties, including appearance, viscoelasticity, and rheology. Particularly, significant changes in photothermal performance were observed as a result of magnetic regulation of NIR absorption activity. As a result, the CP/Fe3O4@TA coatings achieve effective bacteria killing performance under NIR irradiation, magnetocaloric effect, boric acid adsorption, and aggregation interference. Finally, the hydrogel coating was applied to the beef surface and serves as an effective barrier against the growth of pathogenic bacteria, thereby preserving the freshness and tenderness of the beef. The finding from this work is expected to open up a new way in active nano hydrogel coating for food preservation.

Annotated draft genome sequences of Mucor flavus KT1a and Helicostylum pulchrum KT1b strains isolated from dry-aged beef surface.

Mucor flavus KT1a and Helicostylum pulchrum KT1b were isolated and identified in our earlier study as the two dominant fungal species on dry-aged beef. In this study, we report their genome sequences and annotations.

Novel soy protein isolate films incorporated with phage CAM-21 show strong antimicrobial effects against E. coli O157:H7

Due to their specificity, bacteriophages are becoming more widely used as antibacterial agents in the food industry. However, their effectiveness in food is often compromised by food components that can lead to a loss of their biological activity. In this study, soy protein isolate (SPI)-based packaging films incorporated with Escherichia phage CAM-21 were developed using a solution casting method. CAM-21 was relatively stable at pH 3–11 and temperatures up to 55 °C after 1 h of incubation. It remained active on the surface of raw beef, ground beef, and baby spinach after 36 h at 4 °C. The distribution of CAM-21 in the films was uniform, and its incorporation did not affect the film microstructure. No significant impact on the color, water vapor permeability, opacity, and mechanical properties of the films was observed. The antimicrobial activity of CAM-21-incorporated films was significantly enhanced in beef products inoculated with E. coli O157:H7. CAM-21-containing films significantly decreased the number of bacteria on raw beef samples by up to 1.5 and 2.0 log CFU/g after 3 and 5 days of refrigerated storage, respectively. These findings suggest that SPI films containing Escherichia phage CAM-21 have potential as antimicrobial packaging materials for preserving meat products.

Flash heating process for efficient meat preservation

Maintaining food safety and quality is critical for public health and food security. Conventional food preservation methods, such as pasteurization and dehydration, often change the overall organoleptic quality of the food products. Herein, we demonstrate a method that affects only a thin surface layer of the food, using beef as a model. In this method, Joule heating is generated by applying high electric power to a carbon substrate in <1 s, which causes a transient increase of the substrate temperature to > ~2000 K. The beef surface in direct contact with the heating substrate is subjected to ultra-high temperature flash heating, leading to the formation of a microbe-inactivated, dehydrated layer of ~100 µm in thickness. Aerobic mesophilic bacteria, Enterobacteriaceae, yeast and mold on the treated samples are inactivated to a level below the detection limit and remained low during room temperature storage of 5 days. Meanwhile, the product quality, including visual appearance, texture, and nutrient level of the beef, remains mostly unchanged. In contrast, microorganisms grow rapidly on the untreated control samples, along with a rapid deterioration of the meat quality. This method might serve as a promising preservation technology for securing food safety and quality.

Synergistic effects of ε-poly-l-lysine and lysozyme against Pseudomonas aeruginosa and Listeria monocytogenes biofilms on beef and food contact surfaces

This study investigated the synergistic effects of ε-poly- L -lysine (ε-PL) and lysozyme against P. aeruginosa and L. monocytogenes biofilms. Single-culture biofilms of two bacteria were formed on silicone rubber (SR), stainless steel (SS), and beef surfaces and then treated with lysozyme (0.05–5 mg/mL) and ε-PL at minimum inhibitory concentrations (MICs) of 1 to 4 separately or in combination. On the SR surface, P. aeruginosa biofilm was reduced by 1.4 and 1.9 log CFU/cm2 within 2 h when treated with lysozyme (5 mg/mL) and ε-PL (4 MIC), respectively, but this reduction increased significantly to 4.1 log CFU/cm2 (P < 0.05) with the combined treatment. On beef surface, P. aeruginosa and L. monocytogenes biofilm was reduced by 4.2–5.0, and 3.3–4.2 log CFU/g when lysozyme was combined with 1, 2, and 4 MIC of ε-PL at 25 °C, respectively. Compared to 5 mg/mL lysozyme alone, the combined treatment with 1, 2, and 4 MIC of ε-PL on beef surface achieved additional reduction against P. aeruginosa biofilm of 0.5, 0.8, and 0.7 log CFU/g, respectively, at 25 °C. In addition, 0.25 mg/mL lysozyme and 0.5 MIC of ε-PL significantly (P < 0.05) suppressed the quorum-sensing (agrA) and virulence-associated (hlyA and prfA) genes of L. monocytogenes.

Упаковочные материалы для мясных продуктов на основе полимеров и шунгита.

The article is devoted to the development of polymer composite materials with antimicrobial properties to extend the shelf life of meat products. In the course of the work, polymer compositions and packaging materials based on them with varying shungite contents were obtained for packaging meat products. Based on the experimental results, the optimal content of shungite in the polymer composition to extend the shelf life of meat products was determined. The data of the investigations demonstrated retardation of microbial multiplication on the surface of chilled beef and poultry in the package from the composite material based on polypropylene and 20% shungite compared to the package from pure polypropylene. Furthermore, the actual increase in the shelf life by 3 days was confirmed when the developed materials were used.

Evaluation of Peracetic Acid Treatment on Beef Trimmings and Subprimals Against Salmonella and E. Coli O157:H7 Within Regulatory Retained Water Limitations

The application of antimicrobial treatments to beef trimmings prior to grinding for the reduction of microbial contamination in ground beef has increased recently. However, raw single-ingredient meat products are not permitted by Food Safety and Inspection Services (FSIS) to retain more than 0.49% water resulting from postevisceration processing. The effectiveness of antimicrobials with the limited water retention is not well documented. The objective of this study was to determine the effectiveness of peracetic acid at varied concentrations against E. coli O157:H7 and Salmonella on the surface of beef trimmings and beef subprimals that was applied at industry operating parameters within the retained water requirement. One hundred and forty-four each of beef trimmings and subprimals were used to evaluate the effect of different concentrations of peracetic acid solution on reducing E. coli O157:H7 and Salmonella on surfaces of fresh beef within the FSIS requirement of ≤0.49% retained water from antimicrobial spray treatments using a conveyor system. A ten-strain cocktail mixture was inoculated on surfaces of fresh beef and subjected to water or four different concentrations of peracetic acid (130, 150, 200, and 400 ppm). Spray treatments with 130, 150, and 200 ppm peracetic acid reduced (P ≤ 0.05) E. coli O157:H7 and Salmonella at least 0.2 log on surfaces of beef trimmings and subprimals. Spray treatment with 400 ppm peracetic acid resulted in approximately 0.5 and 0.3 log reduction of E. coli O157:H7 and Salmonella, respectively. Results indicate that all concentrations (130–400 ppm) of peracetic acid significantly reduced E. coli O157:H7 and Salmonella on beef trimmings and subprimals compared to untreated controls. Thus, a range from 130 to 400 ppm of peracetic acid can be used during beef processing to improve the safety of beef trimmings and subprimals when weight gain is limited to ≤0.49% to meet regulatory requirements.

Lactic acid bacteria and spoilage bacteria: Their interactions in Escherichia coliO157:H7 biofilms on food contact surfaces and implications for beef contamination

AbstractThis research explores the interaction between Shiga toxin‐producing Escherichia coli (STEC) O157:H7 and bacteria species commonly found in beef processing environments, specifically Carnobacterium, Lactobacillus, Comamonas, Raoultella, and Pseudomonas. The study investigated how various environmental conditions impact the formation of biofilms and the ability of O157:H7 to transfer from multispecies biofilm onto beef surfaces. For this purpose, a mixture of lactic acid bacteria (LAB), spoilage bacteria (106 CFU/mL), and E. coli O157 (103 CFU/mL) were combined as follows: LAB (T1): Carnobacterium piscicola + Lactobacillus bulgaricus + O157:H7, an spoilage bacteria (T2): Comamonas koreensis + Raoultella terrigena + O157:H7, an spoilage bacteria (T3): Pseudomonas aeruginosa + C. koreensis strain + O157:H7 and only O157:H7 as control (T4). Multispecies biofilms were developed on thermoplastic polyurethane (TPU) and stainless steel (SS) coupons at 10 and 25°C for 6 days, washed and stored for 6, 30, and 60 days at wet (60%–90% RH) and dry (20%–50%, RH) conditions. To evaluate O157:H7 transfer, beef cubes (3 × 3 × 1 cm) were placed on the coupons, followed by a 50‐g weight (7.35 kPa). The experiment was repeated three times in triplicate for each strain combination. Results demonstrate that biofilms formed at 10°C were generally weaker (less biomass) than those at 25°C. Regardless of temperature, more viable O157:H7 cells were transferred to beef from moist biofilms on TPU surfaces. At 25°C, T3 biofilm exhibited the lowest O157:H7 transfer to beef by 1.44 log10 CFU/cm2 (p &lt; 0.01). At 10°C, none of the multispecies biofilm (T1–T3) affected the number of O157:H7 transfers to beef (p &gt; 0.05). Notably, O157:H7 was not detected on food contact surfaces with 30 and 60‐day‐old dry biofilms (T1–T4). Through enrichment, E. coli O157:H7 was recovered from multispecies biofilms T1, T2, and T3. Findings from this study imply that multispecies biofilms contribute to the persistence of O157:H7 under dry conditions, regardless of temperature. These results underscore the intricate influence of multiple environmental factors—including surface type, biofilm age, humidity, temperature, and the presence of other bacterial species—on the risk of beef contamination facilitated by biofilms.

Metabolic and microbial analyses of the surface and inner part of wet-aged and dry-aged beef.

The effects of aging and microbial growth on the metabolome of aged beef were investigated in this study. The metabolome of beef is influenced by the aging method applied. This includes the aging-related changes in metabolism and the presence of microorganisms on the beef during aging that may affect the beef and its quality. The inner part and the trimmed surface of dry-aged (the surface of dry-aged beef is also called the "crust" due to its drying during aging) and wet-aged beef were analyzed by 1 H nuclear magnetic resonance (NMR) spectroscopy over aging periods up to 28 days at intervals of 7 days, and the former also by microbiological analysis. The metabolome detected by 1 H NMR spectroscopy demonstrated changes over the aging time of beef and differed depending on the sampling location (surface or inner part of beef). The influence of the microbiota on changes in the metabolome can be negligible due to the low microbial growth on the surface of dry-aged beef (<3logCFU/g). Therefore, the aging-related metabolism postmortem of the analyzed dry-aged beef might be the main factor for metabolic changes. The significantly (p<0.05) higher amino acids and inosine concentrations and lower inosine 5'-monophosphate concentrations suggested enhanced protein degradation and energy metabolism in the wet-aged beef compared to the dry-aged beef, probably due to the combined influence of the aging and the microbiota on the wet-aged beef and, thus, its metabolic changes.

The Application of Ultraviolet Treatment to Prolong the Shelf Life of Chilled Beef.

This study simulated the storage conditions of chilled beef at retail or at home, and the sterilization and preservation effects of short-time ultraviolet irradiation were studied. The conditions of different irradiation distances (6 cm, 9 cm, and 12 cm) and irradiation times (6 s, 10 s, and 14 s) of ultraviolet (UV) sterilization in chilled beef were optimized, so as to maximally reduce the initial bacterial count, but not affect the quality of the chilled beef. Then, the preservation effect on the chilled beef after the optimized UV sterilization treatment during 0 ± 0.2 °C storage was investigated. The results showed that UV irradiation with parameters of 6 cm and 14 s formed the optimal UV sterilization conditions for the chilled beef, maximally reducing the number of microorganisms by 0.8 log CFU/g without affecting lipid oxidation or color change. The 6 cm and 14 s UV sterilization treatment of the chilled beef was able to reduce the initial microbial count, control the bacterial growth, and delay the increase in the TVB-N values during storage. Compared with the control group, the total bacterial count decreased by 0.56-1.51 log CFU/g and the TVB-N value decreased by 0.20-5.02 mg N/100 g in the UV-treated group. It was found that the TBARS value of the UV treatment group increased during late storage; on days 9-15 of storage, the TBARS values of the treatment group were 0.063-0.12 mg MDA/kg higher than those of the control group. However, UV treatment had no adverse impact on the pH, color, or sensory quality of chilled beef. These results prove that UV treatment can effectively reduce the microbial count on the surface of beef and improve its microbial safety, thus maintaining the quality of beef and prolonging its shelf life. This study could provide a theoretical basis for the preservation technology of chilled beef in small-space storage equipment.

Effect of soy protein isolate nanoparticles loaded with litsea cubeba essential oil on performance of lentinan edible films

Environmental issues caused by plastic packaging materials have gotten increasingly severe, and substantial research has been conducted on environmentally friendly active packaging materials. In this study, the Litsea cubeba essential oil loaded soy protein isolate nanoparticles (LSNPs) with appropriate particle size, high storage stability and salt solution stability were fabricated. The LSNPs with the highest encapsulation efficiency of 81.76 % were added into the lentinan edible film. The microstructures of the films were observed by scanning electron microscopy. The physical properties of the films were measured. The results show that the lentinan film with LSNPs in the volume ratio of 4:1 (LF-4) had the highest elongation at break of 196 %, the lowest oxygen permeability of 12 meq/kg, and good tensile strength, water vapor barrier property, antibacterial property, oxidation resistance and thermal stability. The study suggested that LF-4 film could inhibit the growth of bacteria and delay the oxidation of lipid and protein on beef surface for 7 d.

Determination of beef tenderness based on airflow pressure combined with structural light three-dimensional (3D) vision technology

The main factor affecting beef quality, consumer satisfaction, and purchase decisions is beef tenderness. In this study, a rapid nondestructive testing method for beef tenderness based on airflow pressure combined with structural light 3D vision technology was proposed. The structural light 3D camera was used to scan the 3D point cloud deformation information of the beef surface after the airflow acted on it for 1.8 s. Six deformation characteristics and three point cloud characteristics of the beef surface depression region were obtained by using denoising, point cloud rotation, point cloud segmentation, point cloud descending sampling, alphaShape, and other algorithms. A total of nine characteristics were mainly concentrated in the first five principal components (PCs). Therefore, the first five PCs were put into three different models. The results showed that the Extreme Learning Machine (ELM) model had a comparatively higher prediction effect for the prediction of beef shear force, with a root mean square error of prediction (RMSEP) of 11.1389 and a correlation coefficient (R) of 0.8356. In addition, the correct classification accuracy of the ELM model for tender beef achieved 92.96%. The overall classification accuracy reached 93.33%. Consequently, the proposed methods and technology can be applied for beef tenderness detection.

Fate of Shiga Toxin-Producing Escherichia coli (STEC) and Salmonella during Kosher Processing of Fresh Beef

Traditional kosher meat processing involves the following steps after slaughtering: soaking with water to remove blood, salting to help draw out more blood, and rinsing to remove salt. However, the impact of the salt used on foodborne pathogens and beef quality is not well understood. The objectives of the current study were to determine the effectiveness of salt in reducing pathogens in a pure culture model, on surfaces of inoculated fresh beef during kosher processing, and the effect of salt on beef quality. The pure culture studies indicated that the reduction of E. coli O157:H7, non-O157 STEC, and Salmonella increased with increasing salt concentrations. With salt concentrations from 3 to 13%, salt reduced E. coli O157:H7, non-O157 STEC, and Salmonella ranging from 0.49 to 1.61 log CFU/mL. For kosher processing, the water-soaking step did not reduce pathogenic and other bacteria on the surface of fresh beef. Salting and rinsing steps reduced non-O157 STEC, E. coli O157:H7, and Salmonella ranging from 0.83 to 1.42 log CFU/cm2, and reduced Enterobacteriaceae, coliforms, and aerobic bacteria by 1.04, 0.95, and 0.70 log CFU/cm2, respectively. The salting process for kosher beef resulted in reducing pathogens on the surface of fresh beef, color changes, increased salt residues, and increased lipid oxidation on the final products.

Effect of dry-ageing with Mucor flavus on beef taste and aroma

Okinawa Industrial Technology Centre succeeded in isolating the mould strain, Mucor flavus, creating savoury odours during beef ageing. Several companies already produce dry-aged beef products using the isolated mould strain in Okinawa. It will be a new food content as the Okinawan brand for tourists from all over the world. After trimming, each amino acid in the meat surface was analysed by LCMS and aroma volatile compounds from the headspace were analysed by solid-phase micro extraction followed by GCMS to reveal the effect of dry-ageing with M. flavus on beef taste and aroma. Each amino acid in the surface of dry-ageing beef with the mould increased. It was hypothesised that there is a gradient of moisture content from the surface of the edible part to the inner side of the dryaged beef, where amino acids are easily generated from the protein degradation. Amino acids react with sugars by heating, resulting in a savoury flavour. Besides, the peak number of volatile compounds using GCMS was more detected in dry-aged beef with mould than that in dry-aged beef without mould. There is a high possibility that M. flavus can produce higher polar compounds in beef meat. Several aldehydes detected only in dryaged beef with the mould were related to savoury flavours, such as nutty and boiled meat.

Efficacy of Short Thermal Treatment Time Against Escherichia coli O157:H7 and Salmonella on the Surface of Fresh Beef

Thermal treatment interventions consistently provide effective pathogen reductions. However, the cost of maintaining high temperature of 95°C in order to raise the surface temperature of carcasses to 82°C is very expensive. Therefore, beef processors need to identify thermal application times and temperatures that optimize the treatment effects with less maintenance cost. The objectives of this study were to determine the efficacy of hot water or steam at 71°C for 6 s and cascade e-ion plasma treatment for 2 s in reducing pathogens on the surface of fresh beef compared to the thermal treatment at 82°C for 15 s. Hot water at 71°C for 6 s reduced Escherichia coli O157:H7 and Salmonella by 2.38 and 2.48 log CFU/cm2, while steam treatment at 71°C for 6 s reduced E. coli O157:H7 and Salmonella by 2.94 and 3.06 log CFU/cm2, respectively. Cascade e-ion plasma treatment for 2 s reduced E. coli O157:H7 on surface of fresh beef by 1.89 log CFU/cm2. The findings indicate that short treatment time with appropriate temperature could serve as an effective carcass intervention to improve the safety of fresh beef.

Noncontact Detection Method for Food Texture Assessment Based on Air Puff Combined With Structured Light Imaging

Given the shortcomings of subjectivity and destructiveness associated with traditional methods of measuring food texture parameters (such as fruit firmness and meat tenderness) when using a texture meter, a non-contact measurement method utilizing an Air-puff combined with Structured Light Imaging (ASLI) was proposed in this study. First, the finite element simulation method was used to simulate the airflow impact model and optimize the ranges of the angle and distance parameters. The detection device was then developed, and binocular 3D phenotype acquisition and 3D feature extraction algorithms were investigated. Denoising, point cloud segmentation, greedy projection triangulation, Delaunay triangulation, and surface fitting algorithms were used to process the point cloud, and concave parameters such as depth, mapping area, surface area, and volume of the concave area on the beef surface were obtained. Finally, four typical samples with different meat (beef and chicken) and fruit (kiwifruit and peach) parameters were tested. Five machine learning methods were used to model and analyze the correlation among texture parameters. The results revealed that the model established by the ensemble learning modeling method with extracted concave parameters possessed the highest accuracy. The prediction accuracy of the shear force values of the beef and chicken samples were 0.92 and 0.91. The accuracy of meat and fruit grading was 0.942 and 1.0. Therefore, the non-contact detection method proposed in this study to determine food texture characteristics based on airflow can be used to replace the traditional texture analyzer in food engineering and exhibits good application potential.

Interrelationships Between Visual and Instrumental Measures of Ground Beef Color

Two experiments were conducted to understand the interrelationship among visual color score, Farnsworth-Munsell values, instrumental meat color measurements, and their impact on beef color evaluation. In experiment 1, L*, a*, and b* values and various reflectance traits of the Farnsworth-Munsell 100-Hue Test tiles were measured.Incremental changes of the tiles were used to predict changes in a* values and other color variables that can be seen by a trained visual panel. Regression analysis suggests that trained panelists that pass the Farnsworth-Munsell Hue Test can discriminate a change of 0.95 in a*, 0.9 in b*, and 2.54 in hue angle values when Illuminant A is used. In experiment 2, ground beef was assigned randomly to one of 36 combinations of 3 storage temperatures, 4 storage times, and 3 display temperatures to create a variety of surface colors. A 10% change in ground beef metmyoglobin content corresponded to 3.2 units of a* (R2=0.95). Of all the instrumental measurements, a* (r=−0.97) and chroma (r=−0.97) best represented the red color intensity that panelists saw on the surface of ground beef. Significant surface discoloration occurred at 37.1% metmyoglobin and an a* value of 25.4 (with Illuminant A). Using a 5-point visual lean color scale,the change required in a* value for a unit change visual color score was 4.6. In conclusion, a* and chroma are highly related to visual color scores and changes in metmyoglobin, and a change in a* of 0.95 can be observed by visual panelists that have passed the Farnsworth-Munsell test.