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Questions and Answers
What is the primary biochemical change that occurs in muscle post-mortem?
What is the primary biochemical change that occurs in muscle post-mortem?
What occurs when pH decreases too rapidly in meat?
What occurs when pH decreases too rapidly in meat?
What is rigor mortis primarily a result of?
What is rigor mortis primarily a result of?
Which of the following is a consequence of aging meat during rigor resolution?
Which of the following is a consequence of aging meat during rigor resolution?
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What happens to ATP levels during rigor mortis?
What happens to ATP levels during rigor mortis?
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How does pH affect meat color quality if it remains too high?
How does pH affect meat color quality if it remains too high?
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What are the main flavor potentiators generated during the aging of meat?
What are the main flavor potentiators generated during the aging of meat?
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What is a common result of cooking meat while it is still in rigor?
What is a common result of cooking meat while it is still in rigor?
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What is the primary role of myosin in muscle fibers?
What is the primary role of myosin in muscle fibers?
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How long can raw beef cuts like roasts and steaks be stored in the freezer?
How long can raw beef cuts like roasts and steaks be stored in the freezer?
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What are the main components of muscle tissue?
What are the main components of muscle tissue?
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Which protein constitutes the thin filament in muscle fibers?
Which protein constitutes the thin filament in muscle fibers?
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What is the characteristic arrangement called that is formed by thick and thin filaments?
What is the characteristic arrangement called that is formed by thick and thin filaments?
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Which of the following enzymes is used for tenderizing meat?
Which of the following enzymes is used for tenderizing meat?
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What percentage of muscle protein is made up by tropomyosin?
What percentage of muscle protein is made up by tropomyosin?
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What is the main function of the sarcolemma in muscle fibers?
What is the main function of the sarcolemma in muscle fibers?
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What is a characteristic of cooked sausages?
What is a characteristic of cooked sausages?
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What distinguishes fresh smoked sausages from fresh sausages?
What distinguishes fresh smoked sausages from fresh sausages?
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Which preservation method is primarily used alongside salting and curing?
Which preservation method is primarily used alongside salting and curing?
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What is the primary purpose of curing in meat preservation?
What is the primary purpose of curing in meat preservation?
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How does salting preserve meat?
How does salting preserve meat?
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What is a limitation of the smoking process in meat preservation?
What is a limitation of the smoking process in meat preservation?
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Which of the following best describes dry sausages?
Which of the following best describes dry sausages?
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What effect does heating have on meat?
What effect does heating have on meat?
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Study Notes
Food Chemistry - Meat
- Meat is animal tissue used as food. It most often refers to skeletal muscle and associated fat. It may also refer to non-muscle organs like lungs, livers, skin, brains, bone marrow, and kidneys.
- Main sources of meat in the Philippines include pig, goat, carabao, cow, chicken, and horse.
US Per Capita Meat Consumption (1970-1996)
- Data is presented in a table, showing retail weight figures for different types of meat (beef, veal, pork, lamb, chicken, turkey, fish) from 1970 to 1996.
Heme Iron Sources
- A table showing milligrams of iron in various meats (3 oz. cooked). Beef (calves liver, sirloin), pork (ground lean, tenderloin, ham), lamb (loin), veal (loin), and chicken (breast) are listed.
Total Fat Content
- A bar graph illustrates total fat (grams) per 3-ounce serving of various cuts of meat. Meat types include several cuts of Beef, Pork, Lamb and Chicken.
Calories per Serving
- A bar graph showcasing the calorie count (for 3 ounce serving) across a variety of different cuts of Beef, Pork, Lamb and Chicken. The meat types include various cuts of Beef, Pork, Lamb, and Chicken.
Cholesterol Per Serving
- A bar graph demonstrating cholesterol content (mg) in different cuts of meat (3 oz serving). Cuts of beef, pork, lamb, and chicken are displayed.
Pork
- Culinary name for meat from domestic pigs (Sus scrofa). Often refers specifically to fresh meat but can be used as a general term.
- One of the most commonly consumed meats worldwide. In 2006, nearly 100 million metric tons of pork were consumed globally.
2006 Worldwide Pork Consumption
- A table detailing pork consumption in different regions. This includes the metric tons (millions), per capita (kg), and region. The data represents a breakdown globally, including totals. Key regions are China, EU25, US, Russia Federation, Japan, and others.
Beef
- Culinary name for the meat of bovines (domestic cattle).
- Can be cut into steaks, pot roasts, short ribs, or ground.
- Blood can be used in blood sausage.
Veal
- Meat from young calves (usually male).
- Known for its delicate taste and tender texture.
- Characteristic odor is sour and aromatic.
- Best age is 4-14 weeks.
- Typically hung for 8 days prior to use.
Lamb, Hogget or Mutton
- Culinary names for the meat of domesticated sheep.
- Lamb is meat from year-old or younger sheep.
- Hogget or mutton is meat from older sheep, depending on age and characteristics.
- Lamb meat comes from animals between one month and one year, averaging 5.5 to 30 kilograms in weight.
- Highest meat quality is from 2 to 4 year old sheep.
Goat Meat
- Taste is similar to lamb.
- Prepared in various ways (stewed, curried, baked, grilled, barbecued, minced, canned).
- Nutritionally healthier than mutton.
- Lower in fat and cholesterol, and comparable to chicken.
- Contains more minerals than chicken
- Lower in total and saturated fats compared to other meats.
Horse Meat
- Culinary name for meat cut from a horse.
- Slightly sweet, tender, low in fat, high in protein.
Sausage
- Type of food usually consisting of ground meat, animal fat, salt, and spices, and sometimes other ingredients (e.g., herbs).
- Can be fresh or preserved by curing, drying or smoking.
Sausage Classification
- Categorization of sausage based on methods. Includes cooked, cooked smoked, fresh, fresh smoked, and dry sausages. Specific processes explain the types of preparations used in sausage-making.
Hot Dog
- Type of fully cooked, cured and/or smoked moist sausage with a soft, even texture and flavor. Traditionally made from beef, pork, or a combination of both.
Ham
- Thigh and rump of any slaughtered animal, often strictly the haunch of a pig/boar.
Storage and Preservation of Meat
- Drying: An ancient food preservation method often combined with salting and curing. Protects against water holding and aroma degradation in meat
- Cooling/Freezing: Meat freezing preserves freshness over long durations by freezing the meat, while cooling slows down lipid oxidation.
- Curing: Variety of preservation and flavoring processes for meat. Often uses salt, sugar, and nitrate/nitrite. Commonly coupled with smoking. Increases the product shelf life by eliminating bacterial contamination.
- Salting: Addition of salt inhibits growth of spoilage-causing microorganisms. Draws water from microbial cells through osmosis.
- Smoking: Process of flavoring, cooking or preserving food via smoke from burning/smoldering of plant material. Primarily effective in surface application, antimicrobial and antioxidant activity
- Heating: Causes grayish-brown color, protein coagulation, releasing juices. Reduces the water holding capacity and increase the pH of a meat product.
- Tenderizing: Process of using plant enzymes (ficin, papain, bromelain) to tenderize meat.
Storage Times
- Table presenting freezer and refrigerator storage times for beef, lamb, pork, and poultry.
Meat Aroma
- Raw meat has a weak aroma but heating enhances it.
- Meat aroma is a complex combination of volatile aroma constituents, non-volatile flavor substances and flavor enhancers.
Meat Composition
- Water: ~75%
- Protein: ~18%
- Lipid: ~3%
- Non-protein Nitrogen: ~1.6%
- Carbohydrates: ~1.2%
- Minerals: ~0.7%
- Vitamins: Traces
Muscle Cells
- Unique in converting chemical energy (ATP) to mechanical energy, allowing them to work.
- Basic unit is the muscle cell, measuring 10-100 µm in diameter and several centimetres long.
Muscle Structure
- Muscle fibers are organized into bundles, then surrounded by layers of connective tissue (epimysium, perimysium, endomysium).
- Myofibrils are composed of thin and thick filaments (actin and myosin), creating a light/dark pattern under electron microscopy.
Sarcolemma
- Thin membrane surrounding each muscle fiber.
- Site where motor nerve endings terminate, transmitting signals for muscle contraction.
Sarcoplasm
- Fluid within the muscle fiber, suspending the myofibrils.
- Contains roughly 2000 myofibrils per muscle fiber.
Myofibrils
- Protein structures inside muscle fibers comprising thick and thin filaments.
- Thick filaments are primarily myosin, composing ~45% of muscle protein.
- Thin filaments are primarily actin, making up ~20-25% of muscle protein.
Thick Filaments
- Principal protein of the A band is myosin.
- Myosin molecular weight is ~470,000-480,000 Daltons.
- Contains ~400 myosin molecules per thick filament
Thin Filaments
- Core component of the I-band in muscle tissue.
- Composed predominantly of actin protein. Representing ~20-25% of muscle protein.
- Actin structure exists in two forms, G-actin and F-actin
Actin
- Globular (G-actin) and fibrous (F-actin) forms.
- G-actin molecular weight is around 42,000-48,000 Daltons.
- F-actin is a polymer of G-actin with a 92% alpha-helix structure.
Tropomyosin
- 2 stranded alpha helix protein, representing ~5% of muscle protein. Typical molecular weight is 33,000 - 37,000 Daltons.
- Length is around 400 Å. Lies within actin's double helix groove. Each tropomyosin interacts with 7 G-actin units.
Connective Tissue
- Elastin and Collagen, important protein components of connective tissue.
- Collagen (principal connective tissue protein) is composed of tropocollagen units.
- Toughness of muscle tissue is related to collagen content. Collagen is converted to gelatin by moist heat treatment.
Adipose Tissue
- Adipocytes (fat cells)
- Surface fat (subcutaneous)
- Intramuscular fat (marbling)
- Marbling is related to tenderness and flavour grade of meat.
Post-mortem Changes in Muscle
- Biochemical reactions following animal death lead to muscle conversion into meat.
- Aerobic pathway ceases upon blood removal at slaughter.
- Anaerobic pathway begins temporarily, converting glucose to lactic acid, impacting pH and meat quality.
- A drop in pH affects meat quality.
Effect of pH on Meat Quality
- Rapid pH decrease can trigger protein denaturation, leading to lower water-holding capacity and pale myoglobin.
- High pH might result in darker meat color and dry meat surface.
pH Decline in Meats
- Graph displays pH change over 24 hours post-mortem for different carcass types (DFD, Normal, PSE).
Generation of Meat Flavor
- ATP degradation during aging produces ADP, AMP, IMP (inosinemonophosphate), and ammonia, contributing to cooked meat flavor.
Rigor Mortis and Aging
- Rigor mortis is the post-mortem stiffening of the carcass. Depletion of muscle ATP leads to actomyosin protein formation.
- Aging is the process of allowing rigor's resolution (muscle relaxation). Structural alterations in the myofibrils happen during this process.
- Aging is associated with loss of muscle elasticity, increase in muscle tension, and sarcomere shortening, which can affect meat toughness.
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