8. Meat products (new)

What are the three main functions of meat packaging?

• Protects meat from contamination

• inhibits certain microbial growth (depending on aerobic/anaerobic conditions)

• reduces/eliminates evaporative weight loss.

Why do consumers associate bright red meat colour with freshness?,

Bright red colour comes from the reaction of muscle myoglobin (a haem pigment) with oxygen, forming oxymyoglobin (MbO) consumers associate this red colour with freshness

Which type of packaging film is used for fresh meat display, and why?

Oxygen-permeable film, because it lets O2 react with myoglobin to form bright red oxymyoglobin (MbO), the colour consumers prefer.

Name the three most common meat pigment forms and their colours.

Myoglobin (Mb, purple), oxymyoglobin (MbO, bright red), and metmyoglobin (metMb, brown).

What is the chemical difference between Mb/MbO and metMb?

Mb and MbO have iron in the ferrous state (Fe2+) metMb forms when the iron is oxidised to the ferric state (Fe3+). MbO forms by O2 binding to Mb (oxygenation) metMb forms by oxidation, not ligand binding

What is 'blooming' in fresh meat colour development?

The process (about 15 minutes to 1 hour) where a freshly cut, purple deoxygenated Mb surface reacts with air O2 to form a bright red MbO layer 2-6 mm deep.

How does storage temperature affect meat colour stability?,

Lower temperatures slow the oxidation of MbO to metMb - browning is postponed from about 48 hours at 5degC to about 1 week at 0degC.

What percentage of surface pigment oxidation to metMb typically causes consumer rejection of meat?,

About 20%.

What are the three key gases used in modified atmosphere packaging (MAP) and their roles?

Oxygen (oxygenates pigments, influences aerobic/anaerobic bacterial growth), Carbon dioxide (inhibits some bacterial growth by extending the lag phase), and Nitrogen (inert 'ballast' gas to offset CO2's high solubility in meat/water).

For which meat products is high-O2 MAP typically used, and for which is low/no-O2 MAP used?

High-O2 MAP is used for fresh red meats to keep them bright red

Low/no-O2 MAP (paired with high CO2) is used for cooked, cured, and processed meats — excluding oxygen here prevents rancidity (oxidation of fats) and stops colour fading in those products.

What O2 and CO2 concentrations characterize typical MAP for fresh red meat?

Higher O2 (60-80% vs 20% in air) to encourage penetration, and high CO2 (20-40%) to inhibit undesirable microbial growth.

What colour does meat show under vacuum packaging, and why?

A dark purple appearance, because residual O2 is removed so almost no MbO layer forms mainly deoxyMb (purple) with a thin metMb layer remains - less suitable for retail display but ideal for storage/transport.

Why is vacuum packaging best done soon after slaughter rather than after prolonged ageing?,

Aged meat has decreased respiratory activity, so its CO2 production (which inhibits Pseudomonas spoilage) becomes much less effective.

What happens to vacuum-packed meat when it is removed from the pack?,

It 'blooms' normally, reoxygenating to bright red MbO on exposure to air.

Which spoilage bacterium is particularly inhibited by high CO2 in packaging, and what grows instead?,

Pseudomonas is inhibited, high CO2 instead encourages lactic acid bacteria growth, which are less likely to cause spoilage.

Which three plastics are commonly laminated together for MAP films, and why?,

Polyethylene (sealing ability), ethyl vinyl alcohol (gas impermeability), and nylon (strength) - combined to benefit from each material's properties.

What are the three main categories of pasteurized/heated meat products?,

Cooked ham, cooked sausages, and sliced products.

What distinguishes pasteurized from sterilized heated meat products?,

Pasteurized products (e.g. cooked ham, liver sausage, blood sausage) must be kept refrigerated below 7degC sterilized products (e.g. luncheon meat, corned beef, frankfurters) are shelf-stable.

What defines 'stabilization' of a pasteurized meat product?,

Reaching a centre temperature of about 70degC, achieved by the combined killing and inhibition of surviving pathogens/parasites/viruses using inhibitors (salt, nitrite, food-grade acids), plus refrigerated storage below 7degC.

List the main manufacturing steps for cooked ham.,

Deboning hams, injecting brine into muscles, massaging/tumbling, filling and closing cans/moulds, pasteurising, chilling (water or cold air), refrigerated storage, and optional post-pasteurization treatment (e.g. smoking, grilling).

What pH requirements must cooked ham meat meet for good water binding?,

pH at 1 hour post-slaughter >5.8 (to avoid PSE) and pH at 24 hours between 5.6-6.3 (to avoid DFD).

What is brine and what does it typically contain?,

A solution of salt, nitrite, phosphates, sugars and antioxidants in water may also include acidity regulators, flavour enhancers, flavours, spice extracts, starch, proteins and carrageenan.

Which brine ingredients are mainly responsible for shelf-life and safety?,

Salt, nitrite, and food-grade acids/their salts.

Which brine ingredients form and stabilize cured colour?,

Nitrite and (iso)ascorbate.

Which brine ingredients support moisture retention and tenderness?,

Salt and oligophosphates, starches, proteins, and gums.

What is the legal maximum input level of nitrite (NaNO2) in pasteurized meat products?,

120 mg/kg.

What does tumbling do to meat during cooked ham manufacture?,

Promotes uptake and even distribution of brine, speeds salt diffusion, ruptures connective tissue filaments (collagen), and produces a sticky exudate that binds meat pieces together after cooking.

How does salt (NaCl) contribute to water binding in meat products?,

It increases the net negative charge of actomyosin, causes swelling of myofibrils, and extracts actomyosin.

How do phosphates contribute to meat product texture and stability?,

They alter muscle pH and water-binding capacity, release myosin/actin from actomyosin, act synergistically with salt, and have antioxidant capacity by chelating metal ions.

Why is water added to meat products?,

As a carrier for ingredients in brines, to compensate for cooking/smoking losses, to help dissolve myofibrillar proteins together with salt/phosphates, and to influence juiciness, bite and texture.

What is the Feder count and what legal limit applies to it?,

A calculation approximating the water-to-protein ratio in meat products products declaring 80% or more meat content must have a Feder count of 4.0 or less.

What is nitrosomyoglobin and how does it form?,

The pink/dark-red pigment of cured meat, formed when nitrite (via nitric oxide) reacts with myoglobin, converting it through metmyoglobin to nitrosomyoglobin, giving the characteristic cured colour after heating.

Distinguish Kochwurst from Bruhwurst in cooked sausage classification.,

Kochwurst involves precooking collagen tissue above 70degC

Bruhwurst involves chopping under low temperature (below 10degC).

What is comminution and why is it used in meat products?,

Mincing, bowl chopping, or flaking meat into small particles it breaks up connective tissue and fat, allows tougher/lower-value cuts to be used, and lets particle size and adhesion be controlled to create different texture

What ingredients are used in burgers and what do they do?,

Minced beef, fat, NaCl and extenders like soy protein improve cohesiveness after cooking and reduce cost/fat content

Vegetable binders (starches, carrageenan) can also be added

What is Mechanically Separated Meat (MSM) and how is it produced?,

Meat recovered by grinding bones into paste and forcing it through small holes or high pressure to separate soft tissue from bone remnants

• Type 3 (low pressure, structure intact)

• Type 4 (high pressure, structure destroyed, only allowed in cooked/emulsified products)."

Why can MSM not be counted as 'meat' for labelling (QUID) purposes?,

Both MSM types must be declared separately as MSM and are legally excluded from the meat content calculation.

What is a meat emulsion/batter and how does it differ from a true emulsion?,

A meat emulsion (batter) has dispersed fat particle size typically 1.0 micrometre or more, much larger than a true emulsion's particle size of 0.1 micrometre or less (e.g. mayonnaise).

What three factors determine a successful, stable meat emulsion/batter?,

Meat quality (myofibrillar protein content and functionality), handling knowledge/technology (salt, temperature, water, chopping), and additional binders.

Which proteins are mainly responsible for gel formation and emulsification in emulsion-type meat products, and why?,

Myosin (mainly) and actin

myosin has a hydrophobic head and hydrophilic tail, making it a natural emulsifier.

According to Stokes' Law, how does fat globule size affect emulsion/batter stability?,

Smaller fat globules are more stable but require more protein to coat and stabilize them.

What happens if meat batter is over-chopped during processing?,

It destroys the protein membranes coating fat globules, 'breaking' the emulsion/batter.

Why does pre-rigor meat make a more effective emulsion/batter than post-rigor meat?,

Its higher pH increases protein functionality and water-holding capacity, making it 50-100% more effective for emulsion stability.

What role does vacuum processing play during batter chopping/mixing?,

It reduces air holes in the batter (increasing capacity/stability) and improves cured colour development - vacuum gives good cooked colour, while non-vacuum gives a gray cooked colour.

What is GDL (glucono-delta-lactone) used for in sausage manufacture?,

It hydrolyses to gluconic acid, lowering pH for shelf life and giving a mild acid taste - an alternative to lactic acid bacteria fermentation.

What are the composite phases held together by salt-soluble proteins in cooked sausage structure?,

Fat tissue, fat droplets, and collagen/muscle particles, enveloped in a continuous phase of salt-soluble proteins in water.

Name three protein sources used to support moisture/fat retention in comminuted meat products.,

Meat tissue proteins (myosin, actin, collagen), separately added meat proteins (blood plasma, gelatine), and non-meat proteins (milk, egg, soy, potato, wheat).

What is the key food-safety risk of re-packing pasteurized meat products after slicing?,

Severe risk of recontamination (e.g. with Listeria monocytogenes), so products must be stored below 4degC, preferably vacuum or gas packaged.

What does EU Regulation No 2073/2005 require for Listeria monocytogenes in ready-to-eat meats?,

Absence in 5x25g before the food leaves the factory less than 100 cfu/g in 5 samples during shelf-life on the market unacceptable levels require product recall."

What causes greenish discoloration sometimes seen in re-opened, anaerobically packaged sliced meats?,

Previous growth of lactic acid bacteria.

How is a dry sausage defined?,

A mildly salted, comminuted meat product stabilized by acidification and drying, developing typical flavour and structure through extended ripening.

What produces the acidification in fermented sausages?,

Lactic acid, produced as a metabolite by lactic acid bacteria (naturally present or added as starter cultures) fermenting carbohydrates, or chemical acidification with GDL.

How do semi-dry and dry fermented sausages differ in ripening time, pH and water activity?,

Semi-dry: short ripening (3-20 days), pH below 5.2, aw below 0.95, moisture above 35%, often smoked. Dry: long ripening (over 4 weeks), pH 5.2-5.8, aw below 0.91, moisture below 35%, not smoked.

What is water activity (aw) and how does it vary across meat products?,

The relative amount of free (unbound) water

Ranges from about 1.00-0.99 in fresh meat down to about 0.70 in Parma ham, with cooked sausages about 0.93-0.96 and fermented sausages about 0.80-0.95."

What are the three key steps in processing dry sausages?,

Manufacturing, fermentation, and ripening.

What role does salt play in fermented sausages?,

Contributes taste, preservation, extraction of myosin (supports texture formation), and catalyses lipid oxidation.

What role do spices play in fermented sausages?,

Contribute to taste/flavour (e.g. pepper stimulates lactic acid bacteria to produce acid) some spices may inhibit unwanted lipid oxidation.

What requirements must starter culture lactic acid bacteria meet in dry sausage production?,

Growth in the presence of salt and nitrite, tolerance of a broad temperature range and increasing drying stress, rapid lactic acid production, no biogenic amine production, and a positive contribution to flavour.

What is the main functional role of Micrococcus bacteria in dry sausage fermentation?,

They produce enzymes that reduce nitrate to nitrite and reduce peroxides formed during fermentation, preventing oxidation and discoloration.

What is the legal maximum nitrite input for dry-cured meat products?,

120 mg NaNO2/kg, plus an additional allowance of 120 mg KNO3/kg.

What four functions does nitrite serve in dry cured meat products?,

Inhibits undesirable micro-organisms (e.g. C. botulinum, L. monocytogenes), forms cured colour (nitrosomyoglobin), contributes positively to taste/flavour, and acts as an antioxidant above about 50 ppm.

What natural colorants are permitted in sausages?,

Curcuma (E100), Carmine/cochineal (E120), Caramel (E150), Carotene, Capsanthin/paprika extract (E160c), and Beetroot red/betanin (E162).

What defines an 'uncured' meat product labelled as having no added nitrate/nitrite?,

It relies on naturally occurring nitrates in ingredients like sea salt or celery powder to help preserve the product, rather than added synthetic nitrite/nitrate.

How is surface mould (mycotoxin risk) controlled in dry sausages?,

By climate control during ripening, mild smoking in the early wet stage, treating the surface with natamycin or potassium sorbate if needed, or applying desirable starter mould cultures such as Penicillium nalgiovense.

What is the recommended prevention method against parasites (e.g. Toxoplasma gondii) in raw fermented meat products?,

Freezing raw meat at -18degC for at least 1 week before processing.

Why is salt reduction difficult in dry sausages despite being nutritionally desirable?,

High salt (3-4%) is needed for technological stability

KCl substitution is limited by bitter taste

Reduction to 3.0% is only feasible with lower pH (below 5.0) and fast fermentation, always checked via a pathogen survival challenge test.