Term
| What are the factors that affect the colour of meat, as seen by the consumer? |
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Definition
1. Viewing conditions (state of the meat, lighting)
2. Individual ability amongst humans to detect colour
3. Structure and texture of the muscle |
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Term
| _____ is responsible for the pigment of muscles |
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Definition
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Term
| What is responsible for the pigment of blood? |
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Definition
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Term
| Where is hemoglobin found, and what is it's function? |
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Definition
| Red blood cells, for O2 and CO2 transport |
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Term
| Where, specifically, is myoglobin found, and what is it's function? |
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Definition
| Sarcoplasm, for storing O2 in muscle fibers |
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Term
| What is myoglobin composed of? |
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Definition
| Globular protein, nonprotein heme component |
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Term
| T or F: Myoglobin is similar in size to Hemoglobin |
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Definition
| False, hgb is 4x bigger than mgb |
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Term
| True or False: The oxidation state of the heme ring has major influence on meat color |
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Definition
| True! (Fe2+ ferrous vs Fe3+ ferric) |
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Term
| How much of the total meat pigment is dependent on myoglobin, and what does it depend on? |
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Definition
| 80 to 90%, depending on hemoglobin (so, how well the animal has been bled out) |
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Term
| T or F: Catalases & cytochrome oxidases do not contain heme units in their structure? |
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Definition
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Term
| Which type of muscle fibers have more myoglobin? (red or white) Why? |
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Definition
| Red, b/c involved with strong aerobic metabolism |
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Term
| Does myoglobin content in an animal increase, or decrease with age, and why? |
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Definition
Increases, b/c mgb loses it's affinity for oxygen as age increases
- need higher concentration to store O2 |
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Term
| Which has a higher mgb content, locomotive muscles, or support muscles? |
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Definition
| Locomotive, duuuh, cuz we need dat shizzz to get arooouunnd |
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Term
| Which has the highest mgb content: Females, Intact Males, or Castrates? |
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Definition
| Intact males (e.g. Bulls also have dark red meat) |
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Term
| Why do game animals have more mgb than reared/domestic animals? |
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Definition
| Because they have developed the need for more muscle content (Chicken breast vs Pigeon breast, Wild ruminants vs farm ruminants) |
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Term
| How could diet affect meat colour? |
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Definition
| Iron-containing diets supply Fe for mgb and hgb (e.g. veal is from calves fed only milk) |
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Term
| What colour is myoglobin? |
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Definition
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Term
| What is the colour of fresh cut meat? Why? What contributes to this? |
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Definition
| Purple. Because oxidized. Myoglobin, also called deoxymyoglobin |
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Term
| What is the form of iron in uncut meat? |
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Definition
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Term
| T or F: Ferrous iron can only react with water |
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Definition
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Term
| What is another name for purple mgb? |
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Definition
| Reduced myoglobin (and ferrous) |
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Term
| What is another name for bright red mgb? |
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Definition
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Term
| What is another name for brown mgb? |
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Definition
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Term
| What is Blooming, and how is it done? |
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Definition
Important for grading meat quality
- cut b/w 12th and 13th rib (separates hind and forequarter)
- top 2-6mm of meat reacts with O2 for 15-60 mintes |
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Term
| What reaction occurs during blooming? |
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Definition
| deoxymyoglobin -> oxymyoglobin |
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Term
| T or F: O2 is conserved at high pH and temperature |
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Definition
| False, it is used up, due to environment effects on enzyme activity |
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Term
| If meat is kept near freezing, what effect does it have on enzyme activity, and consequently meat colour? |
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Definition
| Enzyme activity and O2 utilization is reduced, meat is cherry red |
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Term
| What happens when there is only a small amount of O2 available when exposed? |
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Definition
| Fe becomes oxidized and turns brown; called metmyoglobin |
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Term
| What is the ion reaction during the conversion of oxymygb to metmgb? |
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Definition
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Term
| What temperature should meat be stored at to postpone browning for 2 to 7 days? |
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Definition
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Term
| What happens after meat is exposed to air for 2 to 3 days? |
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Definition
| If >20% is oxidized, sales decrease |
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Term
| Which vitamin influences the amount of metmyoglobin in carcasses? |
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Definition
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Term
| T or F: There will be more light scattering AND lower pH in paler meat |
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Definition
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Term
| Is light scattering due to reflection or refraction? |
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Definition
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Term
| When a cut appears dark, is it because of Scattering, Reflectance, or Refractance? |
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Definition
| None of these. It's due to absorption :) |
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Term
| Paleness is caused by free _____ which is located between ____ cells |
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Definition
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Term
| T or F: As Free water increases, light reflectance, absorption, and color intensity all increase |
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Definition
| True, except for absorption, it decreases |
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Term
| DFD has ___ water holding capacity (WHC) due to ____ concentrations of intracellular water [high/low] |
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Definition
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Term
| With DFD meat, light reflection is ______ and color absorption is _______ [minimized/maximized] |
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Definition
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Term
| As WHC increases, drip loss ________ |
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Definition
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Term
| What is the L-value, and how is it measured? |
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Definition
| Lightness, with a colourimiter |
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