Unit 3 Flashcards
What is the smell associated with Cis-3-hexane-1-ol =
cut grass
Flavors have 2 modes of formation:
Thermal and Enzymatic (including fermentation)
One way of classifying compounds is based on their mode of formation; flavors can be generated wither ____________ or by ___________ during food processing.
naturally
heat treatment
Natural flavors are mainly ______________________ (phytochemicals) of the living tissue, formed during the natural growth cycle of the organism by the action of enzymes, whereas flavors produced by heat treatment is the result of thermal _____________ and oxidation of various food ingredients and their complex interactions.
secondary metabolites
degradation
The initial or primary precursors of flavors are the polymers found in food such as ________, ________, _________ and DNA which can undergo either enzymatic or thermal hydrolysis, to produce the intermediate precursors mainly dimers and monomers
proteins
lipids
polysaccharides
The type of flavor effect depends on the conditions of ____________ and the type of the initial precursors found in the particular food product
processing
In terms of composition, thermally generated flavors are richer in ____________ compounds compared to enzymatically produced flavors
heterocyclic
What are the 3 groups of reactions that account for most chemical transformations of intermediate precursors in food:
- Maillard & Strecker reactions (caramelization)
- Thermal decomposition
- Lipid oxidation
Name the possible carcinogen in red raw meat:
N-glycolylneuraminic acid
The raw meat has no particular appealing flavor, however, during various processes of cooking, the initial precursors in meat, produce water soluble intermediate precursors, such as :
- glycopeptides
- free nucleotides
- peptides
- amino acids
- amino-sugars
- free sugars
- fatty acids
The meat flavor, therefore, is the combined effect of the chemicals produced from the _____________ of these intermediates and the products formed from the amino-carbonyl interactions, such as between the reducing sugars and amino acids this reaction is known as the Maillard reaction or ________________ since it is responsible also for the brown color produced when foods are heated
thermal degradation
non-enzymatic browning
__________ and __________ (dipeptides) are by far the most abundant amino compounds in red meat followed by sulfur containing amino acids (_____________ and ___________). Nucleotides and lipids can also undergo either enzymatic or thermal hydrolysis to produce nucleosides and free fatty acids as important intermediate precursors
Anserine and Carnosine
Cysteine and cystine
What are the intermediate precursors in meat:
- Amino acid/sugars
- Sulfur amino acids
- Fatty acids
- Thiamine & Ribose-5’-phosphate
Thiamin (vit B1) generates different _____________ at different pH values
volatile degradation products
Vitamin B1 structure can be classified has a ________________
heteroatom (sulfur, nitrogen + oxygen)
T or F: Thiamin produces hundreads of degradation products
T
T or F: Heterocyclic compounds have very low threshold values
T
T or F: Sugars caramelize at relatively high temperatures
T
If the sugar reacts with an amino acid then the temperature at which the sugar will degrade gets much _________
lower
What is the key aspect if we want to obtain beautiful browning reactions?
The key is of course dehydration, too much water will not generate browning (concentrated solution is best for that)
Fructose is what type of sugar?
Keto-sugar
Glucose is what type of sugar?
Aldehyde-suagr
When sugars are put in solution, they get into the ________________ and they are then able to receive amino acids
open-ring
Process of ring opening and closing is called:
tautomerization