OBJECTIVES 1. Stability of vitamins; 2. Changes during food storage and treatment;

1. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS OBJECTIVES 1. Stability of vitamins; 2. Changes during food storage and treatment; 3. Chemical reactions of vitamins - examples; 4. Ascorbic acid in Maillard reaction.

2. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 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).

3. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 2 2. Stability

4. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 3 2. Stability of vitamins added to breakfast cereal products

5. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 5 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 ofcarotenoids (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;

6. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 7 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

7. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 8 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.)

8. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 9 3. General factors influencing availability, loss and stability of vitamins 3.5. Storage – compared to thermal treatment, less losses of vitamins

9. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 10 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.

10. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 11 4. Thermal transformations 4.1. Vitamin A:

11. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 12 4. Thermal transformations 4.2. Vitamin В6 – anemia; reactions ofdecarboxylation, transamination, racemization, С-С split etc.)

12. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 13 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).

13. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 14 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.

14. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 15 4. Thermal transformations 4.3. Vitamin C (E300) Reducing agent in foodstuffs Biological activity Antioxidant 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

15. ! VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 16 4. Thermal transformations 4.3. Vitamin C (E300) Lactone of 2-keto-L-gulonic acid L-ascorbic acid D-ascorbic acid L-isoascorbic acid D-isoascorbic acid - Easily oxidized – formation of ascorbate anion and dehydroascorbic acid

16. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 17 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.

17. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 19 4. Thermal transformations 4.3. Vitamin C (E300) - Carbonyl component in the Maillard reaction;

18. ! VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 20 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)

19. VITAMINS – STABILITY AND THERMALTRANSFORMATIONS 21 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