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

1 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). !

2 2. Stability VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS

3 2. Stability of vitamins added to breakfast cereal products VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS

4 3. General factors influencing availability, loss and stability of vitamins 3.1. Initial content VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS

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; VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 3. General factors influencing availability, loss and stability of vitamins

6 - milling : ex. cereals – separation of the grains husks and the germs (rich of vitamins); losses – possible solutions: enrichment with vitamins or use of whole grains. VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS

Blanching and thermal treatments Blanching – inactivation of the enzymes, microorganisms reduction (positive effect on the vitamins stability) 10 minutes VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 3. General factors influencing availability, loss and stability of vitamins

8 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.) VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 3. General factors influencing availability, loss and stability of vitamins 3.4. Blanching and thermal treatments

Storage – compared to thermal treatment, less losses of vitamins VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 3. General factors influencing availability, loss and stability of vitamins

Influence of other compounds added - oxidants – hypochlorite, ozone (degradation of vitamins С, В1) - SO 2 – 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 N 2 O 3 – the primary nitrosating agent) - acidity regulators (acidulants) – improving stability of vitamin C, thiamin etc. VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 3. General factors influencing availability, loss and stability of vitamins

1 4. Thermal transformations 4.1. Vitamin A: VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS

Vitamin В6 – anemia; reactions of decarboxylation, transamination, racemization, С-С split etc.) VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 4. Thermal transformations

13 Case study: Influence of the chemical structure of the vitamin on the thermal stability and availability (50 ths of the XIX century in USA) – milk products consumed by children; Observation – part of the kids suffer from convulsive seizures; VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 4. Thermal transformations 4.2. Vitamin В6 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).

14 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. VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 4. Thermal transformations

Vitamin C (E300) VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 4. Thermal transformations L-ascorbic acid Antioxidant in foodstuffs Role of the L-ascorbic acid in foods Reducing agent in foodstuffs Carbonyl component in Maillard reaction Biological activity Inhibitor of the enzymatic browning Inhibitor of the non-enzymatic browning

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

17 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. VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 4. Thermal transformations 4.3. Vitamin C (E300)

Vitamin C (E300) VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 4. Thermal transformations

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

20 Carbonyl component in the Maillard reaction – participate as reductone; participates in Strecker degradation (formation of sorbamic acid) VITAMINS – STABILITY AND THERMAL TRANSFORMATIONS 4. Thermal transformations 4.3. Vitamin C (E300) !

21 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) DHA – dehydroascorbic acid Sorbamic acid