Flavonoids and sugar assessment in gelatin coated apples after UV-B exposure

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UNIVERSITY OF PISA

Departments of Agricolture, Food and Environment

Veterinary Sciences

Master Degree in

Food Biosafety and Quality

Flavonoids and sugar assessment in gelatin coated apples after

UV-B exposure

Supervisor

Prof.ssa Annamaria Ranieri

Advisor

Author

Prof. Mike Frank Quartacci

Elia Nuti

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1. Introduction………...4

1.1 Changes in diet tendencies. A short overview……….……….4

1.1.2 Changing habits, changing laws……….6

1.2 Nutraceutical food…....……….7

1.2.1 Nutraceutical and functional food, meaning………..7

1.3 The antioxidants………...9

1.3.1 Antioxidants, meaning and action mechanism………...9

1.3.2 Antioxidants, role in human diet………...…..………...10

1.3.3 The Phenol group……….……….………11

1.3.4 Phenol compound biosynthesis………..………..14

2. State of art………....19

2.1 Flavonoids in vitro and in vivo research………....………….19

2.2 The apple fruit…...………..20

2.2.1 Apple origins and spread………...………20

2.2.2 Major flavonoids and their amount in Apple…………..………...22

2.3 Health-promoting effects of apple flavonoids….…..………...26

2.4 Bioavailability………...………..28

2.4.1 Flavonoids bioavailability ………..………...28

2.4.2 Post harvest apple treatment………...30

2.5 UV………...………...………....……….32

2.5.1 UV, the love/hate relationship among plant and light…....………..32

2.5.2 The UV-B and plant physiology………...…..…….……….33

2.5.3 Phenol compounds response after UV-B irradiation…...………34

2.5.4 Apple’s reaction after UV-B, differences between peel and flesh……....……….35

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2.6.1 The biofilm and the edible coatings in food industry………...36

2.6.2 Edible Coatings and Edible Films, how and why…....……….37

2.6.3 Edible coatings properties………...……….38

2.6.4 Collagen’s nutraceutical features………...………..42

3. Aim of the work………..……….44

4. Materials and Methods………..……….45

4.1 Coating experiment……….………….…………...45

4.1.1 The samples of the experiment………..…...….………...45

4.1.2 Coating solubilization………..…………..…..………...45

4.1.3 Samples preparation……...…….……….….…...………46

4.2 Interaction of coating and UV-B………...…….………..………..….46

4.2.1 Sample preparation and UV-B treatment for the second experiment...46

4.3 Flavonoid glycosides extraction. ………….….………...48

4.4 HPLC-MS analysis………….……….…...………...49

4.5 Quantification of phenol compounds.………....……….…………...51

4.6 The sugar assessment………….…….………...………..…52

4.6.1 Preparation of solutions………….…...……….………...52 4.6.2 Procedure……….…….………....53 4.6.3 Sugar determination………….…...………....54 4.6.4 Concentration calculation……...……….…………...55 4.7 Statistical analysis………..………...………..………..56 5. Results………..57

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5.2 Sugar assessment ………..……….……….62

5.3 Second experiment, coating and UV-B effects on phenol profile at day ………..………..………...65

5.4 Coating and UV-B effects on phenol profile at day 14………...………68

5.5 Multivariate discriminant analysis………...71

6. Discussion………...75

6.1 Phenol compounds profile of the first experiment…...……….…77

6.2 Sugar outcomes of the first experiment...……….………...80

6.3 Second experiment flavonoid outcomes; differences between times of detection...81

6.4 Multivariate discriminant analysis between day 0 and day 14……...85

7. Conclusions………...87