Enzymatic & non enzymatic browning

Basic overview of Enzymatic Browning and Non-Enzymatic Browning(Maillard Reaction & Caramelization) and their significance

1. ROLE OF ENZYMATIC BROWNING IN FOOD STORAGE ( Chhavi - Sec M)

2. ENZYMATIC BROWNING Enzyme assisted bio-chemical process that results in the formation of brown pigments, hence the name enzymatic browning Conditions required: Exposure to air/oxygen, warm temperature, enzyme: phenolase , pH : 5-7

3. COMMON SITES OF ENZYMATIC BROWNING FRUITS Apple, Pear, Banana

4. VEGETABLES Potato, Mushroom, Brinjal

5. SEA FOOD Lobsters, Shrimps, Crabs

6. TYPES DESIRABLE Tea, Coffee, Dried fruits eg : Raisins, Figs etc UNDESIRABLE Fruits, Vegetables, Sea foods etc

7. BASIC MECHANISM Phenolic substrate acted upon by the enzyme is converted to quinones , which in turn polymerise to form dark brown-black, insoluble polymers called melanins Involves a series of bio-chemical reactions

8. WHY IS BROWNING DETRIMENTAL? Discolored foods are unappealing & low on consumer acceptance Directly affects the quality of food (Quality Indicator) Limits the shelf-life & decreases market value of the product Contributes to post-harvest losses

9. PREVENTION BLANCHING: Mild heat treatment(70-100°C) for enzyme inactivation; Often used as a pre-treatment; Types: Hot water, Steam, Microwave

10. INHIBITORS Sulphites ( Sulphur dioxide) added as a reducing agent Ascorbic Acid as an anti-oxidant

11. ACIDULANTS Reduce the pH that impairs the enzyme activity Enzyme activity is pH dependent Acids like citric acid, phosphoric etc may be added

12. IRRADIATION Food subjected to ionizing radiations eg : gamma rays, x-rays Enzymes are inactivated Low consumer acceptance

13. BROWNING DURING STORAGE FRUITS AND VEGETABLES SEA FOOD During transport & warehouse storage, F & V subjected to mechanical injury (bruising) Cells are broken, enzyme released, that leads to browning It contributes to post-harvest losses Also called melanosis Common in crustaceans Leads to discoloration of the shell & the muscle Decreases the market value of otherwise highly prized products

14. POST-HARVEST LOSSES Major concern for developing countries like India 50% F & V wasted every year Losses that occur between harvest and the moment of human consumption i.e during handling, transport, storage etc.

15. MINIMISING POST-HARVEST LOSSES HARVESTING & FIELD HANDLING Harvesting should be done in cooler parts of the day Harvest should be shifted to shade as early as possible

16. PACKING-HOUSE Harvested crop should reach a packing-house Cleaning, grading, packing etc unit operations are carried out This concept of packing house can reduce post-harvest losses considerably

17. COLD STORAGE Cold storage to be set up in F & V producing regions & in major consumption centres Optimum temperature to be maintained (so as not to cause chill injury) This also ensures supply round the year

18. MAILLARD REACTION

19. INTRODUCTION REACTION OF SIMPLE REDUCING SUGARS N FREE AMINO ACIDS IN THE PRESENCE OF HEAT. BEGINS AT ABOUT 140 DEGREE CELSIUS PRODUCE BROWN COLOURED MELANOIDINS

20. PROCESS

21. 3 BASIC STEPS

22. FACTORS AFFECTING MAILLARD REACTION…

23. WATER 0%MIN 30%MAX 100% MIN

24. WHY WORRY ABOUT IT???

25. PRODUCTS caramel made from milk and sugar the browning of bread into toast the color of beer, chocolate, coffee, and maple syrup self-tanning products the flavor of roast meat the color of dried or condensed milk

26. CARAMELLIZATION BY: A.SANGEETA SEC- M

27. is one of the most important types of browning processes in foods. Carmelization leads desirable color and flavor in bakery's goods, coffee, beverages, beer and peanuts. Undesirable effects of caramelization are for example burned sugar smell and blackening. Caramelization

28. what is caramelization reaction As no enzymes are involved in the caramelization process, it is a non-enzymatic browning reaction. Sugars in a dry condition or in concentrated form when heated undergo a series of reaction leading to the formation of brown color pigment called as caramels.

29. WHAT HAPPENS DURING CARAMELIZATION ?? During caramelization several flavor compounds as well as polymeric compounds are produced. Caramels are complex mixture of various high molecular weight components. They can be classified into three groups : Caramelans (C 24 H 36 O 18 ) Caramelens (C 36 H 50 O 25 ) Caramelins (C 125 H 188 O 80 )

30. CARAMELAN : they are the 1 st polymers formed during polymerization. They are soluble in water as well as in alcohol. They are significantly bitter in taste , on further heating these they get converted into Caramelen. CARAMELEN: these are dark brown in color &bitter in taste . They are not soluble in water but soluble in alcohol. CARAMELIN : these are almost black brown in color and very bitter in taste . It is completely insoluble in water &partially soluble in alcohol.

31. CARAMEL AROMATICS

32. Diacetyl is an important flavor compound, produced during the first stages of caramelization. Diacetyl is mainly responsible for a buttery or butterscotch flavor. Besides diacetyl hundreds of other flavor compounds are produced for instance furans which have a nutty flavor . Maltol has a toasty flavor. Esters and lactones have a sweet rum like flavor.

33. Process: The process of caramelization starts with the melting of the sugar at high temperatures, followed by foaming (boiling). At this stage sugar decomposes into glucose and fructose. This is followed by a condensation step, in which the individual sugars lose water and react with each other to form dimers eg: difructose-anhydride . The next step is the isomerization of aldoses to ketoses and further dehydration reactions. The last series of reactions include both fragmentation reactions (flavor production) and polymerization reactions (colour production).

34. APPLICATIONS IN FOOD INDUSTRY

35. This process is often used in cooking in order to evoke richer and more complicated flavors from food. It is also critical in making of candy and is responsible for the flavor, texture, and appearance of caramel. Caramel is used to enhance the attractiveness of baked goods by supplementing the inadequate and irregular coloring power of refined ingredients. Sausage casings are commonly dipped in solutions of caramel color to give them the desired tone. In chocolate milk , caramel colors can create an almost muddy appearance. In cookies, very pleasing dark shades can be achieved by caramel color

36. SUMMARY

37. Decomposition of sucrose: in which one molecule of sucrose has to break down into fructose and glucose. Decomposition of fructose and glucose into aroma molecules: producing typical aroma flavor. Oligomerization of fructose and glucose: in which 2 sugar molecule dimerize to form a new molecule.

38. REFERENCES http:// www.slideshare.net/davidmbwiga1990/lecture-4-browning-reaction http:// www.food-info.net/uk/colour/enzymaticbrowning.htm CHEMICAL CHANGES IN FOOD DURING PROCESSING by – O. Fennema isopaninsulation.com/technologies/fruit-ripening-plants www.waterconf.org

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