Transcript P3 3 Vitamins thermal treatment - e

VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
OBJECTIVES
1. Stability of vitamins;
2. Changes during food storage and treatment;
3. Chemical reactions of vitamins - examples;
4. Ascorbic acid in Maillard reaction.
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
1. Roles of the vitamins
1.1. As coenzymes or their precursors;
1.2. As a components of the defensive antioxidant systems;
1.3. As a factors of the genetic regulation;
1.4. Special functions (vitamin A – vision, ascorbate anion participates
In reactions of hydroxylation).
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
2. Stability
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
2. Stability of vitamins added to breakfast cereal products
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
3. General factors influencing availability, loss and stability of vitamins
3.2. Changes after harvesting
-enzymatic
-chemical – in results of treatment with chemical reagents
(pineapple, banana – augmentation of polyphenols; tomato – increase of
carotenoids (lycopene, β-carotene)
3.3. Influence of the initial treatment – chopping, peeling, washing,
milling etc.
-peeling (industrially) – often accompanied with alkaline
treatment; loss of folic acid (vitamin B9, vitamin С, thiamin; negligible
losses;
-washing– loss of water soluble vitamins;
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
3. General factors influencing availability, loss and stability of vitamins
3.4. Blanching and thermal treatments
Blanching – inactivation of the enzymes, microorganisms
reduction (positive effect on the vitamins stability)
10 minutes
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
3. General factors influencing availability, loss and stability of vitamins
3.4. Blanching and thermal treatments
Thermal treatment – influence of lot of parameters on the vitamins
stability (рН, aw (moisture content), cations, oxygen, type of the raw
material, presence of other compounds, etc.)
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
3. General factors influencing availability, loss and stability of vitamins
3.5. Storage – compared to thermal treatment, less losses of vitamins
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
3. General factors influencing availability, loss and stability of vitamins
3.6. Influence of other compounds added
- oxidants – hypochlorite, ozone (degradation of vitamins С, В1)
- SO2 – protective effect on vitamin С, but destructive for thiamin,
vitamin В6
- nitrites – used as preservatives and for better look of meat; to avoid
formation of nitrosamines vitamins C and E is added (due to the oxidation of
vitamins is formed NO, but not a N2O3 – the primary nitrosating agent)
- acidity regulators (acidulants) – improving stability of vitamin C,
thiamin etc.
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
4. Thermal transformations
4.1. Vitamin A:
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
4. Thermal transformations
4.2. Vitamin В6 – anemia; reactions of
decarboxylation, transamination,
racemization, С-С split etc.)
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
4. Thermal transformations
4.2. Vitamin В6
Case study: Influence of the chemical structure of the vitamin on the thermal
stability and availability (50ths of the XIX century in USA) – milk products
consumed by children; Observation – part of the kids suffer from convulsive
seizures;
Solution: changing the pyridoxal with pyridoxine (reason – the thermal treatment
of the milk during sterilization about 60% of the B6 (pyridoxal form) is destroyed
but the pyridoxine is stable).
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
4. Thermal transformations
Other possibility – binding to proteins
(formation of amide bonds)
Interaction with free radicals (obtained during
degradation of vitamin C, lipid peroxidation,
light absorption etc.) – degradation and loss of
vitamin activity.
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
4. Thermal transformations
4.3. Vitamin C (E300)
Biological activity
Antioxidant
in foodstuffs
Reducing agent
in foodstuffs
L-ascorbic acid
Inhibitor of the
enzymatic browning
Inhibitor of the
non-enzymatic browning
Carbonyl component
in Maillard reaction
Role of the L-ascorbic acid in foods
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
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4. Thermal transformations
4.3. Vitamin C (E300)
L-ascorbic acid
D-ascorbic acid
Lactone of 2-keto-L-gulonic acid
L-isoascorbic acid
D-isoascorbic acid
- Easily oxidized – formation of ascorbate anion and dehydroascorbic acid
VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
4. Thermal transformations
4.3. Vitamin C (E300)
Transformations and degradation of vitamin C
Tree major type products are formed:
- polymeric products;
- unsaturated carboxylic acids with 5 or 6 C atoms;
- products of fragmentation with 5 or less C atoms.
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
4. Thermal transformations
4.3. Vitamin C (E300) - Carbonyl component in the Maillard reaction;
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
4. Thermal transformations
4.3. Vitamin C (E300)
Carbonyl component in the Maillard reaction – participate as reductone;
participates in Strecker degradation (formation of sorbamic acid)
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VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS
4. Thermal transformations
4.3. Vitamin C (E300)
Carbonyl component in the Maillard reaction – participate as reductone;
participates in Strecker degradation (formation of sorbamic acid)
Sorbamic acid
DHA – dehydroascorbic acid
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