Question

1. How does lemon juice inhibit browning? (4 pts)

2. How does Fruit Fresh inhibit browning? (4 pts)

3. How does blanching inhibit browning? (4 pts)

4. How does the sugar solution inhibit browning? (4 pts)

5. What color is chlorophyll in acidic conditions? Basic conditions? (2 pts)

6. What color is anthocyanin in acidic conditions? Basic conditions? (2 pts)

Answer 1

Food browning is the proces sin which a food undergoes enzymatic or non-enzymatic chemical changes which eventually leads to browning of the food. In enzymatic browning which occurs due to oxidation certain key enzymes called polyphenol oxidase, peroxidase, etc. plays the most important role in making the food turn brown. It may have positive or negative effect on the food.

1) lemon helps in keeping fruits like apple from turning brown due to enzymatic oxidation taking place. SInce lemon is high in vit C (or ascorbic acid) it readily reacts with oxygen before the oxygen can interact with polyphenoloxidase enzyme and thus prevents the fruit from becoming brown. Additionaly, the low pH of lemon also prevents browning by inhibiting the polyphenol ixidase enzyme activity.

2) PLEASE REVIEW THIS QUESTION ONCE. IT SEEMS INCOMPLETE.

3) Blanching is the process in which the food is subjected to mild heating/boiling treatment. It leads to inactivation of the enzymes responsible of browning and thus prevents it.

4) The application of sugar solution to a food reduces the diffusibilty of oxygen which is required for browning to occur and thus inhibits browning. A glucose/glycine heating product most commonly called the Maillard product has strong antioxidant propeties and is therefore widely used as antibrowning agent.

5) Under neutral conditon chlorphyll remains in its soluble form and appears green. However under acidic condition it gets converted into a compound called pheophytin and becomes dull and rustc in appearance, more like loive green to olive brown. In basic pH. it forms another compound called chlorophyllin that appears bright green in color.

6) athocynanin under neutral condition remain purple. However under acidic condiiton the form falvylium ions which makes them appear more of red or pink. On the other hand, under basic condition they form qnuinone type anhydro bases which mparts them with more of bluish green appearance.