CHAPTER MEAT.pdf

# Meat quality characteristics and influencing factors This topic examines the multifaceted nature of meat quality, defining its attributes from various stakeholder perspectives and detailing species-specific characteristics, alongside a comprehensive overview of factors that shape meat quality from animal husbandry to post-mortem handling [3](#page=3). ### 1.1 Defining meat quality Meat quality is defined as the combination of traits that make a meat product attractive, appetizing, nutritious, and palatable after cooking. However, the concept of meat quality varies depending on the context and the observer. Producers tend to focus on quantity and conformation while packers and retailers are concerned with age, marbling, color, and texture. Consumers prioritize tenderness, juiciness, and flavor whereas health officials focus on nutrition and wholesomeness, ensuring the meat is free from pathogens [3](#page=3). ### 1.2 Quality characteristics in different animal species Quality characteristics differ significantly among various livestock species [4](#page=4). #### 1.2.1 Sheep and lamb For sheep and lamb, desirable quality traits include a firm, dry surface and a bright red color. Lamb meat typically presents a bright pink hue, while mutton is bright red. A dark surface and yellow fat can indicate older animals [4](#page=4). #### 1.2.2 Beef Beef quality is assessed by marbling, maturity, and color. Pale pink color is preferred, with fat ideally being white. Dark, firm, and dry (DFD) beef is characterized by a dark color, often associated with a high ultimate pH. Yellow fat in beef is an indicator of older animals [5](#page=5). #### 1.2.3 Pork Pork quality is characterized by a firm, dry surface, a pinkish-red color, and good marbling. PSE (pale, soft, and exudative) pork is undesirable, marked by excessive moisture loss, a soft texture, and a pale appearance [5](#page=5). ### 1.3 Factors influencing meat quality Numerous factors contribute to the overall quality of meat, influencing its characteristics from farm to table. These can be broadly categorized as [7](#page=7): 1. **Types and treatments of animals:** This encompasses the breed, genetics, diet, health status, and pre-slaughter handling of the animal [7](#page=7). 2. **Slaughtering and carcass characters:** The methods used during slaughter and the resulting carcass characteristics, such as chilling rate and rigor mortis development, play a role [7](#page=7). 3. **Variation in composition and structure of muscle:** Differences in muscle fiber type, fat content, and connective tissue amount influence meat quality [7](#page=7). 4. **Various cuts from carcass:** Different anatomical cuts from the same carcass will exhibit varying quality attributes due to differences in muscle usage and composition [7](#page=7). 5. **Postmortem changes:** Biochemical and physical changes that occur in muscle after the animal's death, such as pH decline and protein denaturation, are critical [7](#page=7). 6. **Cooking methods:** The temperature, time, and method used to cook meat significantly impact its palatability and texture [7](#page=7). 7. **Processing treatments:** Techniques like curing, smoking, and marination can alter meat quality [7](#page=7). 8. **Methods of preservation:** Storage conditions and preservation methods (e.g., freezing, vacuum packaging) affect meat quality over time [7](#page=7). ### 1.4 Palatability characteristics of meat Palatability refers to the sensory qualities of meat that are appreciated by the consumer. Key palatability characteristics include [8](#page=8): #### 1.4.1 Appearance Visual appeal is the first aspect of meat quality perceived. Factors affecting appearance include marbling, the presence of DFD or PSE conditions, yellow fat, microbial discoloration, and mold growth [8](#page=8). #### 1.4.2 Color The color of meat is determined by the type, quantity, and molecular state of myoglobin. Myoglobin is purplish-red in its deoxymyoglobin form, changes to bright red when oxygenated (oxymyoglobin), and becomes brown when oxidized (metmyoglobin). Muscular activity, feeding practices, nutrition, glycogen levels, and ultimate pH all influence myoglobin and thus meat color [8](#page=8). #### 1.4.3 Tenderness Tenderness is a crucial attribute for consumer satisfaction. It is influenced by the fat content, the amount of connective tissue, the maturity of the animal, and the specific cut of meat [8](#page=8). #### 1.4.4 Juiciness Juiciness is largely dependent on the fat content and the water-binding capacity of the muscle proteins. Higher fat content and good water-binding properties contribute to a juicier product [9](#page=9). #### 1.4.5 Flavor Flavor is perceived initially as odor, which is attributed to water-soluble compounds, and is further enhanced during cooking. Older animals may exhibit a stronger flavor profile [9](#page=9). --- # Meat curing principles and methods Meat curing is a preservation technique with ancient origins that imparts characteristic flavors and colors to meat products through the use of specific ingredients and methods [15](#page=15). ### 2.1 Historical origins and basic ingredients The practice of meat curing is lost in antiquity, originally serving as a fundamental method for preserving meat, especially during times of plenty and easy availability. Ancient Greek epics from around 1000 B.C. mention salt-cured meat, indicating an early understanding of its preservation qualities. Meat curing has persisted not only as a preservation method but also because consumers have developed a taste for cured products, leading to their continued production as specialty items [15](#page=15). The essential ingredients for meat curing include: * **Salt:** A primary component for preservation and flavor [16](#page=16). * **Sugar (or other sweetener):** Balances the saltiness and contributes to flavor development [16](#page=16). * **Nitrite:** Crucial for color fixation, flavor, and inhibiting bacterial growth, particularly Clostridium botulinum [16](#page=16) [26](#page=26). * **Nitrate:** Acts as a precursor to nitrite, contributing to preservation effects [16](#page=16) [29](#page=29). * **Phosphate:** Often added to pickle cures in commercial operations to aid in water retention and yield [16](#page=16) [37](#page=37). * **Other compounds:** Spices, baking soda, sodium ascorbate/erythorbate (antioxidants), hydrolyzed vegetable proteins, and monosodium glutamate (MSG) may also be used [16](#page=16). > **Tip:** While both sodium nitrate (NaNO3) and sodium nitrite (NaNO2) are used, sodium nitrite is a more direct preservative due to its stronger oxidizing properties. Sodium nitrate is more heat-stable and can be converted to nitrite in the body or during processing [23](#page=23) [29](#page=29). ### 2.2 Mechanism of action of curing agents The efficacy of curing agents, particularly nitrite, lies in their chemical properties: * **Nitrite mechanism:** Sodium nitrite is a strong oxidizing agent that oxidizes essential molecules within bacteria, thereby preventing their colonization of the food. This action is critical for preventing spoilage and the growth of dangerous pathogens [23](#page=23) [26](#page=26). * **Nitrate mechanism:** Sodium nitrate (NaNO3) is also an oxidizing agent. When it oxidizes a chemical compound, one of the reaction products is sodium nitrite. This conversion can occur during food processing or within the gut, effectively making the addition of sodium nitrate a way to introduce sodium nitrite to the food system [29](#page=29). ### 2.3 General principles of curing Regardless of the specific method employed, meat curing generally involves the following fundamental processes: * Penetration of curing ingredients into the meat [33](#page=33). * Dehydration, which reduces water activity and inhibits microbial growth [33](#page=33). * Fixation of color, often due to the reaction of nitrites with myoglobin to form nitrosylmyoglobin, a stable pink pigment [33](#page=33). ### 2.4 Curing methods Several techniques are used for meat curing, each with its own procedure and characteristics: #### 2.4.1 Dry curing Dry curing involves the direct application of a curing mixture (salt, nitrite/nitrate, and sugar) to the surface of the meat [34](#page=34). * **Curing mixtures:** Typical mixtures might contain 6 pounds of salt, 2.5 ounces of nitrate or 0.25 ounces of nitrite per 100 pounds of meat, or roughly 1 ounce of curing mix per pound of meat [34](#page=34). * **Procedure:** The curing mix is rubbed into the meat and held for a period. Natural meat juices are withdrawn, mixing with the salt to form a brine that further penetrates the meat [34](#page=34). * **Time required:** Curing can take 2 to 2.5 days per pound of meat at low temperatures [35](#page=35). * **Advantages:** Produces a high-priced specialty product; the resulting dryness and firmness make the cuts less perishable; offers a better flavor profile [35](#page=35). * **Disadvantages:** High cost due to inefficient space utilization and significant labor requirements; high inventory levels result from the slow curing process; the final product can have a harsh, salty flavor [35](#page=35). #### 2.4.2 Pickle curing (brine curing) Pickle curing involves submerging meat cuts in a salt-based solution (brine or pickle) containing the curing ingredients until they are fully penetrated [36](#page=36). * **Ingredients:** Uses the same basic ingredients as dry curing, dissolved in water [36](#page=36). * **Procedure:** Cuts are submerged in the brine. The strength of the brine is measured using a salinometer or salometer and adjusted as needed. A common brine strength is 70°S [36](#page=36). * **Time required:** Curing typically takes 2 to 2.5 days per pound [36](#page=36). #### 2.4.3 Artery pumping This method involves injecting the curing pickle directly into the arterial system of the meat, usually larger cuts like hams [37](#page=37). * **Procedure:** A needle is inserted into an artery, allowing the pickle to distribute throughout the cut [37](#page=37). * **Pumping schedule:** Typically involves adding 8-10% of the pickle by weight of the meat [37](#page=37). * **Pickle strength:** A common pickle strength is 65°S brine [37](#page=37). * **Holding time:** After pumping, the meat is held for 1 to 3 days to allow for further diffusion [37](#page=37). * **Additives:** Phosphates are commonly used to enhance water retention and increase yield [37](#page=37). #### 2.4.4 Stitch pumping Stitch pumping is a variation where a needle with multiple openings is used to inject the pickle directly into the meat tissue in multiple locations, adaptable to various cuts [38](#page=38). * **Procedure:** Operators make 3 to 5 injections ("stitches") per cut of meat [38](#page=38). * **Pickle composition:** A typical pickle used contains 10% by weight of 65°S brine, with 150 parts per million (ppm) of nitrite and alkaline phosphate [38](#page=38). #### 2.4.5 Other modifications Other modifications mentioned include conventional dry salt curing, conventional pickle curing, and thermal/hot cures (smoking). Smoking is often combined with curing methods to impart flavor, color, and additional preservation [33](#page=33) [53](#page=53). --- # Meat smoking processes and smoke characteristics Smoking is a crucial process in meat preservation and flavor development, historically discovered by nomadic humans hanging meat near fires, and it remains closely intertwined with curing practices today [39](#page=39). ### 3.1 The role of smoking in meat processing The primary purposes of smoking meat include the development of aroma and flavor, preservation, creation of new products, development of color, formation of a protective skin on emulsion-type sausages, and protection from oxidation [40](#page=40). ### 3.2 Modern smoking equipment and parameters Modern smokehouses are insulated, hermetically sealed, and thermostatically controlled units where smoke is generated using devices that utilize sawdust or woodchips [41](#page=41). #### 3.2.1 Optimal temperature parameters The optimal internal temperature for meat during smoking varies based on the curing method: * **Hard-cured meat:** internal temperature of 120-125ºF, stored at room temperature [42](#page=42). * **Mild-cured meat:** internal temperature of 142-124ºF, refrigerated storage [42](#page=42). * **Mild-cured and lightly smoked meat:** internal temperature of 142-145ºF, refrigerated storage [42](#page=42). #### 3.2.2 Humidity control Humidity plays a critical role during smoking: * **During smoking:** High humidity (85-90%) is maintained because a moist meat surface is more receptive to smoke constituent deposits [42](#page=42). * **During heating and drying:** Humidity is reduced to 60-70% to facilitate skin formation on the surface. This skin helps retain moisture, leading to improved tenderness during heating to the desired internal temperature [42](#page=42). #### 3.2.3 Smoking time The duration of smoking depends on the type of cure and desired smoke intensity: * **Heavy smoke:** 12-14 hours for hard-cured meat [43](#page=43). * **Heavy smoke:** 6-8 hours for mild-cured meat [43](#page=43). * **Light smoke:** 2-3 hours for mild-cured meat [43](#page=43). ### 3.3 Smoke generation #### 3.3.1 Types of wood Various non-resinous hardwoods and other materials are suitable for smoke generation, including hickory, oak, beech wood, driftwood, cedar, rice husk, peat, and corn cobs, often used as assorted sawdust [43](#page=43). #### 3.3.2 Smoke generation temperature The temperature at which wood burns is critical for smoke quality and safety: * Smoke is generated through the destructive distillation and partial oxidation of wood, ideally in the region of 300 ºC [44](#page=44). * Temperatures above 400 ºC lead to more complete oxidation, producing increased amounts of CO$_2$ and vapor. At temperatures above 800 ºF, only CO$_2$ and H$_2$O are produced [44](#page=44). * Crucially, the quantity of carcinogenic 3-4 benzypyrene increases significantly above 400 ºC. Therefore, smoke generation temperatures should not exceed approximately 400 ºC, with an optimal around 375 ºC [44](#page=44). * Burning temperature is regulated by controlling the air draft to the burning wood shavings or sawdust. The moisture content of the sawdust, ideally around 20%, also helps control the temperature [44](#page=44). ### 3.4 Characteristics of smoke Smoke is composed of both a vapor phase and a particulate (particle) phase [45](#page=45). #### 3.4.1 Smoke composition * Approximately 95% of the desirable smoke constituents are found in the vapor phase [45](#page=45). * The amount of particulate phase, which includes soot and tar, is dependent on the air draft at the burning front [45](#page=45). * Too little air results in dark smoke [45](#page=45). * Too much air leads to complete combustion [45](#page=45). * A desirable smoke color is grey-white [45](#page=45). * An increase in the particulate phase leads to a bluish color in the smoke [45](#page=45). #### 3.4.2 Key smoke constituents and flavor contribution Smoke constituents include aliphatic acids, alcohols, ketones, aldehydes, phenols, and cresols. It also contains a mixture of waxes and resins, along with minor components like ammonia, xylene, toluene, methyl pyridine, pyridine, carbon dioxide, methane, carbon monoxide, and esters. Aldehydes and phenols are responsible for approximately 50% of the smoke flavor [46](#page=46). > **Tip:** Understanding the smoke generation temperature is critical for both flavor development and consumer safety due to the formation of carcinogenic compounds at higher temperatures. ### 3.5 Smoking as part of the curing process Smoking is listed as one of the key components in meat processing alongside ingredients and various curing methods, indicating its integral role in the overall production of cured meat products [53](#page=53). --- # Sausage production and types Sausage production involves the preparation, processing, and preservation of ground meat products packed into casings, with various classifications based on processing methods and moisture content [49](#page=49). ### 4.1 General composition and classification of sausages Sausages primarily consist of meat as the main ingredient, with a limited inclusion of cereal flour or potato flour in specific varieties. They are broadly classified into six main groups [49](#page=49): * Fresh [49](#page=49). * Smoked [49](#page=49). * Cooked [49](#page=49). * Cooked and smoked [49](#page=49). * Semi-dry [49](#page=49). * Dry [49](#page=49). ### 4.2 Detailed sausage production process The production of a specific type of sausage follows a multi-step process: #### 4.2.1 Meat preparation The meat is first hashed or ground into a fine paste [50](#page=50). #### 4.2.2 Curing and mixing Curing agents are then added to the hashed meat and mixed thoroughly. Salt is typically added to a level of approximately 2.5 percent, and spices to about a 1 percent level within the mixture [50](#page=50). > **Tip:** Proper mixing is crucial to ensure even distribution of curing agents and spices, which affects both flavor and preservation [50](#page=50). #### 4.2.3 Stuffing into casings The blended meat mixture is then placed into a stuffer and subsequently stuffed into casings [50](#page=50). #### 4.2.4 Linking The stuffed sausages are linked by twisting them into individual pieces, often around 2.5 inches in length [51](#page=51). #### 4.2.5 Cooking and cooling Sausages are cooked to an internal temperature of 65 degrees Celsius and then cooled in water at room temperature [51](#page=51). > **Example:** This cooking step is essential for microbial inactivation and developing the final product texture and flavor [51](#page=51). #### 4.2.6 Optional smoking Alternatively, sausages may be smoked for approximately 30 minutes before the cooking process [51](#page=51). #### 4.2.7 Packaging and storage Following cooking and cooling, individual sausage pieces are separated, packed, and stored under refrigerated conditions to maintain quality and safety [51](#page=51). --- ## Common mistakes to avoid - Review all topics thoroughly before exams - Pay attention to formulas and key definitions - Practice with examples provided in each section - Don't memorize without understanding the underlying concepts

| Term | Definition | |------|------------| | Meat Quality | A combination of traits that make edible products attractive, appetizing, nutritious, and palatable after cooking, with differing perspectives across producers, packers, retailers, consumers, and health officials. | | Marbling | The presence of intramuscular fat, which contributes to juiciness, flavor, and overall palatability of meat. It is a key quality indicator, particularly in beef. | | DFD (Dark, Firm, Dry) | A condition in beef characterized by a dark color, firm texture, and dry surface, often resulting from high ultimate pH levels in the muscle. | | PSE (Pale, Soft, Exudative) | A condition in pork characterized by excessive water loss (exudation), a pale color, and a soft texture, often due to rapid post-mortem pH decline. | | Myoglobin | A protein found in muscle tissue that stores oxygen and is responsible for the purplish-red color of fresh meat. | | Oxymyoglobin | The form of myoglobin that results from the binding of oxygen, giving fresh meat its characteristic bright red color. | | Metmyoglobin | The oxidized form of myoglobin, which results in a brown color in meat, often due to prolonged exposure to air or certain processing conditions. | | Tenderness | A primary palatability characteristic of meat, influenced by factors such as fat content, the amount of connective tissue, and the maturity of the animal. | | Juiciness | The perception of moisture release from meat during chewing, significantly influenced by the fat content and the water-binding capacity of muscle proteins. | | Flavor | The complex sensory experience of consuming meat, with odor being appreciated first due to water-soluble compounds, and often enhanced by cooking. | | Palatability | The degree to which meat is desirable or acceptable to eat, encompassing characteristics like appearance, tenderness, juiciness, and flavor. | | Postmortem Changes | The biochemical and structural alterations that occur in muscle tissue after the death of an animal, significantly impacting meat quality. | | Ultimate pH | The final pH value reached in muscle tissue post-mortem, typically around pH 5.4-5.7 in normal meat, and a key factor influencing color and texture. | | Water Binding Property | The ability of muscle proteins to retain water within the meat, which directly affects juiciness and cooking yields. | | Yellow Fat | A condition observed in older animals where the fat takes on a yellow hue, often due to the accumulation of carotenoid pigments from the diet. | | Meat Curing | A historical preservation method for meat, initially utilizing salt, which has evolved into a practice for creating specialty products due to developed consumer taste and flavor profiles. | | Salt | A fundamental ingredient in meat curing, used to draw out moisture and inhibit bacterial growth, contributing to preservation and flavor. | | Sugar | A sweetener often included in meat curing mixtures, working alongside salt and nitrites to contribute to flavor and aid in preservation. | | Nitrite | A strong oxidizing agent used as a meat preservative, with the chemical formula NaNO2, which prevents bacterial colonization by oxidizing molecules essential for bacterial life. | | Nitrate | A food preservative with the chemical formula NaNO3, which also acts as an oxidizing agent and can be converted into nitrite within the body or during the curing process. | | Dry Curing | A meat curing method where curing ingredients (salt, nitrite/nitrate, sugar) are rubbed directly onto the meat, forming a brine from natural juices, resulting in a firmer, drier product. | | Pickle Curing | A meat curing technique where curing ingredients are dissolved in water to create a brine, into which meat cuts are submerged until the curing agents fully penetrate the tissue. | | Artery Pumping | A curing method involving the injection of a curing solution (pickle) directly into the arterial system of meat cuts, aiming for uniform distribution throughout the entire piece. | | Stitch Pumping | A curing technique where a needle with multiple openings is used to inject a curing solution into various points within a cut of meat, allowing for adaptation to different shapes. | | Salinometer/Salometer | An instrument used to measure the strength of a brine or pickle solution, ensuring it is adjusted to the desired concentration for effective meat curing. | | Phosphate | An additive commonly included in pickle cures and used in stitch pumping to enhance water retention within the meat and increase the overall yield of the cured product. | | Sodium Ascorbate | An additive used in meat curing that acts as an antioxidant, helping to stabilize color and speed up the curing process. | | Sodium Erythorbate | Similar to sodium ascorbate, this additive functions as an antioxidant in meat curing, contributing to color fixation and potentially accelerating the curing reaction. | | Curing | A meat preservation process that involves the addition of salt, sugar, and sometimes nitrites or nitrates to draw out moisture and inhibit microbial growth. It is closely interrelated with smoking and is often practiced concurrently. | | Destructive Distillation | A process where organic materials, such as wood, are heated in the absence of air to break them down into simpler compounds, producing smoke and char. This is a key process in generating smoke constituents from wood. | | Emulsion-type Sausages | Sausages made from finely ground meat and fat emulsified with water, often requiring the formation of a protective skin during smoking to retain moisture and structure. | | Hermetically Sealed | A characteristic of modern smokehouses, meaning they are airtight, preventing the escape of smoke and heat, and allowing for precise control over environmental parameters. | | Internal Temperature | The temperature reached within the meat during the smoking process, which varies depending on the curing method (hard or mild) and desired end product. For mild cured meats, this is typically between 142-145ºF. | | Particulate Phase of Smoke | The solid components within smoke, such as soot and tar, which can affect the color and quality of the smoked product. The amount of particulate matter is influenced by the air supply during smoke generation. | | Phenols | A group of chemical compounds present in smoke that are significant contributors to the flavor of smoked meats, accounting for approximately 50% of the smoke's flavor profile. | | Preservative Effect | The ability of a process, such as smoking or curing, to inhibit the spoilage of food by microorganisms, thereby extending its shelf life. | | Smoke Characteristics | The physical and chemical properties of smoke, including its composition, color, and the phases it contains (vapor and particulate), which influence the final flavor, color, and preservation of the meat. | | Smoke Constituents | The various chemical compounds that make up smoke, including aldehydes, phenols, alcohols, ketones, and acids, many of which contribute to the aroma, flavor, and color of smoked meats. | | Smoke Generation Temperature | The temperature at which wood is burned to produce smoke. This temperature is critical, as temperatures around 300ºC favor destructive distillation, while higher temperatures lead to more complete oxidation and potentially the formation of undesirable compounds like benzopyrene. | | Vapor Phase of Smoke | The gaseous components within smoke, which contain the majority (approximately 95%) of the desirable flavor and aroma compounds responsible for the characteristic taste of smoked meat. | | Woodchips | Small pieces of wood used in modern smokehouses to generate smoke. The type of wood and its moisture content are important factors in controlling the smoke's characteristics. | | Fresh Sausage | Sausages that are typically made from raw meat and are not smoked or cooked before consumption, requiring thorough cooking by the consumer. | | Smoked Sausage | Sausages that have undergone a smoking process, which imparts flavor and aids in preservation, and are often fully cooked. | | Cooked Sausage | Sausages that are fully cooked during the manufacturing process, making them ready to eat or requiring only reheating. | | Cooked & Smoked Sausage | Sausages that are both cooked and smoked, combining the characteristics and benefits of both processes for enhanced flavor and preservation. | | Semi-dry Sausage | Sausages with a moisture content lower than fresh sausages but higher than dry sausages, often requiring cooking before consumption. | | Dry Sausage | Sausages that have undergone significant dehydration and curing, resulting in a long shelf life and typically eaten without further cooking. | | Curing Agents | Substances, primarily salt and spices, added to meat during sausage production to enhance flavor, color, and preservation. | | Casings | The material, either natural or artificial, into which sausage meat is stuffed to form the characteristic sausage shape. | | Linking | The process of dividing a continuous sausage into individual portions by twisting or tying off sections. | | Refrigerated Conditions | Storage of finished sausages at low temperatures, typically between `$0^{\circ}C$` and `$7^{\circ}C$`, to inhibit microbial growth and spoilage. |