Natural Preservatives in Food, Feed, and Cosmetics

June 7-8, 2006 at the Amsterdam Marriott Hotel, Amsterdam, Holland

Pre-meeting workshop

June 6th, 2006, Prior to Meeting

Antioxidant Measurements

Instructor

Dr. Karen Schiach, Rutgers University, NJ, USA

WORKSHOP ON ASSAY METHODS FOR NATURAL ANTIOXIDANTS

Bakto Flavors Conference on Natural Preservatives in Food Systems

Amsterdam, June 2006

Karen M. Schaich, Sc.D.

Dept. of Food Science, Rutgers University

  Outline of workshop:

I.  Overviews:   oxidation processes   ---   radical chain reactions of lipid oxidation

                                                               oxidation initiators

                                                               antioxidant mechanisms

II.  Natural antioxidants found in foods

III.  Critical considerations in assaying antioxidant activity

          Nature of chemical reactions

                          intended applications -- molecular targets

                                                             food matrices

                                                            potential interferences

IV.  The alphabet soup of antioxidant assays in common use

            A.  Antioxidant content assays:   TPC – total phenolic content

      1.  Folin-Ciocalteau

      2.  Prussian blue

      3.  Enzymes

4.  Vanillin-HCl

            5.  Ferrous ammonium sulfate

B.  In vitro antioxidant activity assays – basic reactions and mechanisms

                                                                procedures for running

                                                                what data looks like

                                                                best ways to use and systems for application

           1.  Compounds acting by hydrogen atom transfer (HAT)

                        a. ORAC

                        b. TOSC

c. TRAP

                        d.  Crocin bleaching   

                        e.  Inhibition of lipid oxidation (linoleic acid, LDL, liposomes)

            2. Compounds acting by single electron transfer (SET)

                        a.  FRAP 

                        b.  Cu-RAP or CUPRAC

3.  Compounds acting by both HAT and SET mechanisms (reactions to avoid)

a.  TEAC

b.  DPPH

V.  Evaluation and Recommendations