Isoflavones and Myoglobin in Meat Science

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Questions and Answers

What are isoflavones classified as due to their similar effects to estrogen?

Phytoestrogens (correct)

Glycosides

Polyphenols

Aglycones

Which of the following is primarily responsible for the red color of meat?

Carotenoids

Chlorophyll

Myoglobin (correct)

Hemoglobin

In meat, myoglobin changes color when it combines with oxygen to form which compound?

Deoxymyoglobin

Oxymyoglobin (correct)

Metmyoglobin

Nitrosomyoglobin

What is the primary reaction contributing to non-enzymatic browning in food?

Maillard Reaction Signup and view all the answers

What molecule at the center of myoglobin gives it its function?

Fe Signup and view all the answers

Which factor does NOT control the Maillard Reaction?

Product color Signup and view all the answers

Which compound is formed during caramelization of sugars?

Brown caramel pigments Signup and view all the answers

What enzyme contributes to the process of enzymatic browning?

Polyphenol oxidase Signup and view all the answers

Which of the following components is NOT involved in the overall perception of food flavor?

Color Signup and view all the answers

How do taste and aroma influence each other in the perception of flavor?

Both components can overlap and contribute to overall flavor perception. Signup and view all the answers

What is required to measure taste alone?

The sense of smell must be blocked Signup and view all the answers

Which one of the following is NOT a basic taste according to the classification methods unified in the 20th century?

Umami Signup and view all the answers

Where on the tongue is sweetness primarily detected?

Front Signup and view all the answers

Which of the following accurately describes the detection of sourness and saltiness?

They generate a potential difference through direct interaction with receptor sites. Signup and view all the answers

What is the minimum concentration threshold for sweetness detection?

0.02 M sucrose solution Signup and view all the answers

How does temperature influence the detection of bitterness and saltiness?

Both bitterness and saltiness thresholds increase with rising temperature. Signup and view all the answers

What is termed 'taste blindness'?

Inability to recognize bitterness from phenyl thiocarbamide. Signup and view all the answers

Which part of the electronic systems detect odor and aroma components?

Sensor Array System (SAS) Signup and view all the answers

Which of the following statements is true regarding the recognition mechanism for sweetness?

It involves two polar parts and one non-polar part. Signup and view all the answers

Which bitter component is commonly extracted from plants and used in tonic water?

Quinine Signup and view all the answers

What role do papillae play in taste perception?

They house taste receptors and taste buds. Signup and view all the answers

Which bitter taste substance is primarily found in cacao and chocolate?

Theobromine Signup and view all the answers

What is the main bitter component that undergoes thermal isomerization during the boiling process in beer production?

Humulone Signup and view all the answers

What effect does Naringinase have on Naringin?

Converts it into Prunin Signup and view all the answers

Which of the following acids is NOT an example of an organic acid contributing to sourness?

Nitric acid Signup and view all the answers

What does the Scoville scale measure?

Degree of pungency in chili peppers Signup and view all the answers

Which component is primarily responsible for the spiciness of ginger?

Gingerol Signup and view all the answers

Which component in beer contributes to its characteristic bitterness?

Isohumulone Signup and view all the answers

What is the main bitter component found in Navel and Valencia oranges?

Limonin Signup and view all the answers

Which amino acid is known to show high hydrophobicity and bitterness?

Tryptophan Signup and view all the answers

What ingredient is known for its role as a flavor enhancer and is associated with umami taste?

MSG Signup and view all the answers

How does acetylsalicylic acid relate to astringency in food?

It induces protein coagulation Signup and view all the answers

Which process is primarily used for the production of monosodium glutamate (MSG)?

Fermenting sugars Signup and view all the answers

What is the primary bitter component of citrus fruits that can be hydrolyzed to reduce bitterness?

Naringin Signup and view all the answers

Which compound is used to reduce bitterness in foods such as citrus fruits?

Cyclodextrin Signup and view all the answers

Study Notes

Isoflavones

Isoflavones are polyphenolic compounds found in soybeans.
They act like estrogen, classified as phytoestrogens.
Primarily in glycoside form, converted to aglycones during fermentation/digestion.
Soy isoflavone glycosides: genistin, daidzin, glycitin; aglycones: genistein, daidzein, glycitein.

Myoglobin

Meat pigments include hemoglobin and myoglobin.
Myoglobin gives meat its red color.
In livestock, 90% of iron is in hemoglobin, 10% in myoglobin.
In consumed meat, 95% of iron is from myoglobin.
Myoglobin is a porphyrin structure with iron at its center.
Globin (protein component) is a globular protein.

Changes in Meat Color

Myoglobin combines with oxygen to form oxymyoglobin (pink) then metmyoglobin (brown).
This reaction speeds up with heating.

Non-Enzymatic Browning

Maillard Reaction: Sugars react with amino compounds to form brown pigments (melanoidins).
Affects color, flavor, and aroma (e.g., bread, soy sauce).
Factors influencing Maillard reaction: temperature, water activity, sugar type, pH, protein concentration, amino compounds.
Caramelization: Sugars heat to form brown pigments (caramels). Common in high-sugar foods.

Enzymatic Browning

Caused by polyphenol oxidase, which oxidizes foods to melanin.
Related enzymes: monophenol oxidase, diphenol oxidase.

Control Measures for Browning

Control oxygen levels.
Inactivate enzymes.
Add chelating agents (e.g., phosphates, EDTA) to bind metal cofactors.
Use reducing agents (e.g., ascorbic acid, cysteine).
Adjust temperature.
Dehydrate the product.
Apply irradiation.
Utilize enzyme inhibitors.
Employ high-pressure treatment.

Food Flavor

Flavor involves taste, aroma, tactile sensations, pain, and temperature.
Flavor influences food preference as much as color.
Sensory evaluation was the primary method to determine food flavor. Flavor chemistry (aroma study) introduced the electronic nose and electronic tongue.

Electronic Nose and Tongue

Detect odor/aroma components using a sensor array system (SAS).
Qualitative and quantitative analysis through software, based on electrical signals.
Human pathway: component-receptor binding, biochemical reaction, signal conversion, brain transmission.

Taste of Food

Taste relies on sensory evaluation and analysis.
Taste may be influenced by other taste components (volatile and non-volatile).
20th century: taste classification unified into four basic tastes.
Basic tastes: sweetness, saltiness, sourness, bitterness.

Basic Taste Criteria

Distinct receptors, different from other basic tastes, and cannot be replicated by combining other basic tastes.

Taste Perception in the Tongue

Four basic tastes primarily detected in specific tongue regions:
- Sweetness: front
- Saltiness: near front
- Sourness: middle
- Bitterness: back

Taste Organs

Taste receptors exist beyond the tongue (throughout the oral cavity).
Taste components bind to various taste receptors on the tongue surface.
Tongue contains papillae with taste buds (clusters of 50-150 taste receptors).

Taste Receptor Mechanisms

Taste component contacts taste receptor.
Biochemical reaction occurs.
Chemical energy converts to electrical energy, transmitted to the brain.
Sweet and bitter tastes use G-proteins for signal transmission.

Sourness and Saltiness

Sourness (H+): blocks ion flow.
Saltiness (Na+): permeates ion channels.

Taste Thresholds

Absolute/sensitivity/recognition thresholds: minimum detectable concentration of a taste component.
Basic taste minimum concentrations:
- Sweetness: 0.02 M sucrose
- Saltiness: 0.02 M NaCl
- Sourness: 0.005 M HCl
- Bitterness: 0.002 M quinine

Taste and Temperature

Taste perception varies with temperature, with exceptions for sourness.
Bitterness and saltiness thresholds increase with rising temperature.
Sweetness thresholds decrease up to a certain temperature, varying with sweeteners.

Sweetness

(AH/B) theory: describes how fructose interacts with taste receptors to produce a sweet taste. (Focuses on the hydrogen bonding interactions of specific hydroxyl groups of fructose and the receptor proteins)

Sucralose/Fructooligosaccharides

Sucralose and fructooligosaccharides taste similar to sucrose.

Bitterness

Bitterness is often undesirable but key in some food types (e.g., beer, tea).
Bitter components: alkaloids, glycosides, amino acids/peptides, ketones.
Bitter compounds in foods: quinine, theobromine, and caffeine.

Bitter Taste Components

Beer bitterness: originates from the hop plant constituent Humulone undergoing isomerization (to Isohumulone).
- Other bitter substances: Co-humulone and Ad-humulone.
Citrus fruit bitterness: Flavonoids, naringin (glycoside), limonin.
- naringin can be converted to naringenin by enzyme naringinase, removing the sugar portion.
- Limonin bitterness can be reduced via cyclodextrin removal
Amino acids/peptides: bitter, especially those high in hydrophobicity (Val, Leu, Ile, His, Tyr, Phe, Trp).

Saltiness

Salt (NaCl) is the primary salty taste.
Salty taste is influenced by cationic components of the salt.
Anions influence or modify saltiness.
Chloride (Cl-) has the lowest suppressive power.
Salt affects other taste perceptions (sweet, sour, and bitter).

Sourness

Sourness is due to organic acids (e.g., acetic, lactic, malic, citric, tartaric, ascorbic).

Hot/Pungent Taste

Chili pepper heat: Primarily capsaicin and dihydrocapsaicin, derivatives of Guaiacol.
Scoville scale: measures pungency/stimulation in chili peppers.
Pepper (Piper nigrum) heat: Chavicine in unripe; piperine (less spicy) in ripe.
Ginger heat: Gingerol, shogaol (phenylalkyl ketones) > zingerone (sweet).

Umami

Umami is a savory, pleasant taste (Japanese for "delicious").
Monosodium glutamate (MSG), first isolated in kelp.
Nucleotides (e.g., from dried bonito) also contribute to umami.
Other umami enhancers: hydrolyzed vegetable proteins, yeast extracts, soy extracts, peptides containing cysteine.

Astringency

A taste causing a contraction feeling in the mouth.
Caused by protein coagulation with astringent substances.
Components: tannins, polyphenols, metallic salts, carbonyl compounds.
Milk/cream can reduce astringency by binding polyphenols.

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Description

This quiz explores the roles of isoflavones and myoglobin in meat coloration and composition. Learn about phytoestrogens, the impact of myoglobin on meat's red color, and the Maillard reaction's significance in non-enzymatic browning. Perfect for food science enthusiasts or students!