Enzymatic Browning Experiment
EXPERIMENT # 04
OBJECT:
Determination of different inhibitors that inhibit the rate of Enzymatic Browning in different fruits and vegetable.
REQUIREMENTS: ➢ Citric Acid (1% solution) ➢ Acetic Acid (1% solution) ➢ Ascorbic Acid (1% solution) ➢ Sugar (1%.Solution) ➢ Sodium chloride (1% solution) ➢ Sulfite salt (1% solution) ➢ Samples (Potato, Banana, Apple)
Enzymatic Browning:
Enzymatic browning (oxidative) is a reaction between oxygen and a phenolic substrate catalyzed by polyphenol oxidase result in orthoquinone, which in turn rapidly polymerized to form brown pigments or melanin. This is the common browning that occur in cut fruits and vegetables
[pic]
Phenolase enzymes that have been isolated from food sources are oligomers and contain one copper prosthetic group per subunits. Thus, if damage to plant tissue is sufficient and oxygen and copper are present, browning occurs. Such operation as cutting, peeling and bruising are sufficient to cause enzymatic browning. Phenolase is active at mild Acidic pH (5-7).
Enzymatic browning does not occur in intact plant cells since phenolic compounds in cell vacuoles are separated from the polyphenol oxidase, which is present in the cytoplasm. Once tissue is damaged by slicing, cutting or pulping, however, the formation of brown pigments occurs. Both the organoleptic and biochemical characteristics of fruits and vegetables are altered by pigment formation. The rate of enzymatic browning in fruit and vegetables is governed by the active polyphenol oxidase content of the tissues, the phenolic content of the tissue, pH, and temperature and oxygen availability within the tissues.
This includes: • Reducing agents; • Acidulants • Chelating agents • Complexing agents • Enzyme inhibitors • Enzyme treatments.
Methods to Inhibit Enzymatic Browning:
➢ The elimination of oxygen from the cut surface of fruits or vegetables greatly retards
OBJECT:
Determination of different inhibitors that inhibit the rate of Enzymatic Browning in different fruits and vegetable.
REQUIREMENTS: ➢ Citric Acid (1% solution) ➢ Acetic Acid (1% solution) ➢ Ascorbic Acid (1% solution) ➢ Sugar (1%.Solution) ➢ Sodium chloride (1% solution) ➢ Sulfite salt (1% solution) ➢ Samples (Potato, Banana, Apple)
Enzymatic Browning:
Enzymatic browning (oxidative) is a reaction between oxygen and a phenolic substrate catalyzed by polyphenol oxidase result in orthoquinone, which in turn rapidly polymerized to form brown pigments or melanin. This is the common browning that occur in cut fruits and vegetables
[pic]
Phenolase enzymes that have been isolated from food sources are oligomers and contain one copper prosthetic group per subunits. Thus, if damage to plant tissue is sufficient and oxygen and copper are present, browning occurs. Such operation as cutting, peeling and bruising are sufficient to cause enzymatic browning. Phenolase is active at mild Acidic pH (5-7).
Enzymatic browning does not occur in intact plant cells since phenolic compounds in cell vacuoles are separated from the polyphenol oxidase, which is present in the cytoplasm. Once tissue is damaged by slicing, cutting or pulping, however, the formation of brown pigments occurs. Both the organoleptic and biochemical characteristics of fruits and vegetables are altered by pigment formation. The rate of enzymatic browning in fruit and vegetables is governed by the active polyphenol oxidase content of the tissues, the phenolic content of the tissue, pH, and temperature and oxygen availability within the tissues.
This includes: • Reducing agents; • Acidulants • Chelating agents • Complexing agents • Enzyme inhibitors • Enzyme treatments.
Methods to Inhibit Enzymatic Browning:
➢ The elimination of oxygen from the cut surface of fruits or vegetables greatly retards
References: J. Agric. Food Chem., 2006, Publication Date (Online): April 22, 2006. Enzymatic Browning in Fruits, Vegetables and Sea foods: Maurice R. Marchall, Jeongmok Kim and Cheng Wer ----------------------- Cut apple, banana & potato in to flakes Make 1 % solutions of all inhibitors in 100 ml water Dip flakes of apple, banana &potato in each solution Observe the change in color after 10, 20, 30 & 40 mints