Lecture 15 - Minor Components

Question 1

what is the definition of nutraceuticals

Answer 1

a product isolated or purified from foods that are generally sold in medicinal forms not associated with food

demonstates to have physiological benefits or provides protection against chronic disease

Question 2

what is a nutraceutical found in grapes?

cumin?

Answer 2

grapes: reservratrol
cumin: curcumin

Question 3

what are phenolic compounds

Answer 3

polyphenols are substances which consists of an aromatic ring linked to one or more OH groups, including functional derivatives (ester,s methyl ethers, glycosides, etc…)

Question 4

how many polyphenolics and flavonoids have been identified?

Answer 4

8000 polyphenolics and 4000 flavonoids

Question 5

how are phenolic compounds classified?

Answer 5

1. phenolic acids
2. flavonoids
3. tannins
4. stillbenes and lignans

Question 6

what are types of flavonoids?

Answer 6

flavonols
flavones
flavanols
flavanones
isoflavones
proanthocyanidins

Question 7

what are types of phenolic acids?

Answer 7

hydroxycinnamic (eg p-coumaric, caffeic, ferulic and sinapic acids)

hydroxybenzoic acids (eg gallic acid and protocatechuic acid)

Question 8

are hydroxycinnamic or hydroxybenzoic acids more prevalent in food?

Answer 8

hydroxycinnamic are more prevalent

Question 9

what is the importance of phenolic compounds in general?

Answer 9

• anti-aging properties due to antioxidants

- reduces risk of coronary heart diseases and cancer

Question 10

what causes the antioxidant activity of phenolic compounds?

Answer 10

due to reactivity of the phenol moiety (OH substituent on the aromatic ring)

Question 11

importance of phenolics in the food industry?

Answer 11

• phenolics have effects on fruit maturation (they can be converted to brown pigments and cause loss of nutritional and functional qualities in foods)
• polyphenols cause enzyme catalyse discoloration in cheeses (causes undesirable flavors)
• inhibits lipid oxidation in some foods (eg raw and cooked meat, poultry and fish)
• can bind proteins ,CHOs and reduce digestibility

Question 12

what are 4 ways to determine phenolic compounds

Answer 12

1. sepctrophotometric methods (folin-ciocalteu assay)
2. chromatographic techniques
3. near infrared (NIR FT-IR)
4. Mass spectroscopy (MS)

Question 13

what are types of chromatographic techniques used to determine phenolic compounds?

Answer 13

1. high performance liquid chromatography (HPLC)
2. HSCCC (high counter current chromatography)
3. supercritical fluid chromatography (SFC)

Question 14

describe the folin-ciocalteu assay

Answer 14

• type of spectrophotometric method
• polyphenols reacts with redox reagents (folin-ciocalteu reagent: phosphomolybdic and phosphotungstic acid) to form a blue complex that can be measured

Question 15

what does the folin ciocalteu reagent consist of?

Answer 15

phosphomolybdic and phosphotungstic acid

Question 16

what color is formed when phenolic compounds react with FC reagent?

Answer 16

blue

Question 17

what is the procedure of the Folin ciocalteu assay?

Answer 17

1. place sample in flask
2. add water
3. add FC reagent
4. incubate at room temp
5. add sodium carbonate (Na2CO3)
6. add water and incubate
7. measure blue solution at 765 nm

Question 18

what is an essential step before using chromatographic techniques to determine phenolic compounds?

Answer 18

need to extract phenolic compounds before using the chromatographic techniques

Question 19

describe liquid-liquid extraction for phenolic compound analysis?

Answer 19

a mass transfer operation in which a liquid solution (the feed) initially containing one or more solutes is thoroughly mixed with an immiscible or nearly immiscible liquid (solvent

the solvent exhibits selectivity towards one or more of the components in the feed and has different density

Question 20

what are the 3 types of extraction methods to use before applying chromatographic techniques?

Answer 20

1. liquid liquid extraction
2. solid-liquid (leaching)
3. supercritical fluid extraction (SFE)

Question 21

what is the leaching process also called?

Answer 21

solid liquid extraction

Question 22

describe solid-liquid extraction

Answer 22

• mass transport phenomenon where solids contained in a solid matrix migrates into solvent brought into contact with the matrix
• can be used to recover important food components: sucrose in cane, lipids from oil seeds, etc…

Question 23

what can enhance mass transport phenomena?

Answer 23

concentration gradients
diffusion coefficients
boundary layer

Question 24

describe SFE extraction

what is the most utilized fluid?

Answer 24

• supercritical fluid extraction
• based on the fact that the solvent changes its properties rapidly with only slight variation of pressure when close to the critical point
• most utilized fluid is supercritical carbon dioxide (SC-CO2)

Question 25

reasons to add color (pigments and colorants) to food?

Answer 25

1. to replace color lost during processing 2. to enhance color already present 3. to minimize batch to batch variations 4. to color uncolored food

Question 26

categories of food colors?

Answer 26

1. natural colors 2. nautre-identical colors 3. synthetic colors 4. inorganic colors

Question 27

examples of natural pigments?

Answer 27

anthocyanins: - flavonoids compounds - range: orange, red, blue and purple carotenoids: - lipid soluble - range: yellow, orange, red - eg carotenes, lycopene, lutein, annatoo chlorophyll - lipid soluble - green pigment

Question 28

describe the chemistry of autumn colors

Answer 28

green - chlorophyll A - requires warm temp and sunlight yellow - carotenoids and flavonoids - xanthophylls (subclass ofcarotenoids) are responsible for yellow of leaves - always present in leaves, but appears when chlorophyll is degraded orange - carotenoids - starts degrading at same time as chlorophyll, but at a slower rate red - anthocyanins and carotenoids - synthesis starts at autumn, when sugar concentration increases, sunlight initiates anthocyanin production

Question 29

describe polarity of anthocyanins

Answer 29

polar soluble in solvents, eg alcohol, acetone, dimethyl sulfoxide, water

Question 30

3 steps of anthocyanin analysis?

Answer 30

1. extraction 2. purification 3. measurement

Question 31

describe extraction of anthocyanins

Answer 31

- acetone extraction and chloroform partition - aqueous two phase system (ATPs) - acetone extracts anthocyanins from plant material - then chloroform partitioning further isolates and purifies the pigment. This results in phase separation between aqueous portion (with the anthocyanin, phenolics, sugars, organic acids) and the bulk phase (contains the immiscible organic solvents, lipids, carotenoids, etc...)

Question 32

in analysis of anthocyanins, what is the role of acetone?

Answer 32

extracts anthocyanin from plant material chloroform is used after

Question 33

in analysis of anthocyanins, what is the role of chloroform?

Answer 33

isolates and purifies the pigment results in phase separation between aqueous portion (with the anthocyanin, phenolics, sugars, organic acids) and the bulk phase (contains the immiscible organic solvents, lipids, carotenoids, etc...)

Question 34

procedure of anthocyanin extraction?

Answer 34

1. mix powdered plant material with acetone 2. separate anthocyanin extract (filtrate) from insoluble plant material by a filter paper 3. re-extract plant material with acetone until a clear solution is obtained 4. transfer filtrate to a funnel 5. add chloroform and mix 6. store sample until a clear partition between two phases is obtained

Question 35

describe the purification step in anthocyanin analysis

Answer 35

1. mix sample with water = washes out sugars and acids 2. add ethyl acetate = washes out phenolics 3. add methanol = washes out anthocyanins

Question 36

describe the measurement step of anthocyanin analysis using UV visible spectroscopy (pH differential method) what reaction occurs?

Answer 36

- based on structural transformation of the anthocyanin chromophore as the pH changes. The colors can be measured spectoscopically - it is a method used for rapid measurement of the total anthocyanins, even in presence of polymerized degraded pigments and other interfering compounds reaction: 1. blue quinonoidal base at pH 7 2. orange flavylium cation (oxonium form) at pH 1 3. colorless carbinol pseudobase (hemiketal form) at pH 4.5 4. colorless chalcone at pH 4.5

Question 37

in the pH differential method, what compound is at pH 1?

Answer 37

orange flavylium cation (oxonium form)

Question 38

in the pH differential method, what compound is at pH 7?

Answer 38

blue quinoidal base

Question 39

in the pH differential method, what compounds s are at pH 4.5?

Answer 39

colorless chalcone and carbinol pseudobase (hemiketal form)

Question 40

what do the choices of analytic methods for the detection and determination of food hazards must take into account?

Answer 40

the complexity of the food matrix and the characteristics of the analyte (ie. polarity, hydrophobicity, volatility, thermal stability, chemical reactivity)

Question 41

what are types of hazardous contaminants?

Answer 41

mycotoxins pesticides toxic compounds derived from lipids toxins formed as a result of cooking or processing of food naturally occurring hazards in foods

Question 42

what are examples of pesticides?

Answer 42

Benzimidazoles, CarbamateInsecticides, Halogenated Hydrocabon Pesticides, Organophosphate Insecticides, PyrethrinInsecticides and Triazine Herbicide

Question 43

examples of toxic compounds derived from lipids?

Answer 43

malondialdehyde(MDA), and 4-hydroxyalkenals (4-HAEs), malvalicacid, and sterculicacid

Question 44

examples of toxinds formed as a result of cooking or processing of food?

Answer 44

N-Nitrosamines, Polycyclic aromatic hydrocarbon

Question 45

examples of naturally occurring hazards in foods?

Answer 45

Saxitoxin, Okadaicacid, Brevitoxins, Ciguatoxin, Tetrodotoxin, Safrole, Gossypol

Question 46

how are mycotoxins produced?

Answer 46

when molds (filamentous fungi) develop on food commodities and produces toxins, known as mycotoxins

Question 47

what are main proucers of mycotoxins?

Answer 47

fungal species belonging to the genera aspergillus, fusarium and penicillin

Question 48

how much of the world's total crops per year are affected with unacceptable levels of mycotoxins?

Answer 48

25%

Question 49

what are the major classes of mycotoxins that have impacts on human health?

Answer 49

1. aflatoxins (B1, B2, M1, M2, G1 and G2) 2. ochratoxins (ochratoxin A, OTA) 3. Trichothecenes (deoxynivalenol (DON), T2, HT2) 4. fumonisins (FBs: FB1, FB2, FB3, etc...) and patulin (found in apple products) 5. Zearalenone (ZEA)