Polyphenol Oxidase Enzymes in the Sap and Skin of Mango Fruit

1993 ◽  
Vol 20 (1) ◽  
pp. 99 ◽  
Author(s):  
SP Robinson ◽  
BR Loveys ◽  
EK Chacko
Keyword(s):  
Heat Treatment ◽  
Polyphenol Oxidase ◽  
Catechol Oxidase ◽  
Hexadecyltrimethylammonium Bromide ◽  
Temperature Optimum ◽  
Mango Fruit ◽  
Salicylhydroxamic Acid

Severe sapburn occurs in mango fruit of the cultivar Kensington when sap contacts the fruit, resulting in browning and then blackening of the skin. Both the sap and skin of mango fruit contained considerable polyphenol oxidase (PPO) activity. The sap enzyme was not activated by SDS, was inhibited by hexadecyltrimethylammonium bromide, and was active with both para- and ortho-diphenol substrates. The skin enzyme was activated by SDS, was inhibited by salicylhydroxamic acid and polyvinylpyrrolidone, and was active only with ortho-diphenol substrates. These properties suggest that the sap PPO is a laccase-type enzyme (EC 1.10.3.2) whereas the skin contains the more common catechol oxidase-type PPO (EC 1.10.3.1). The skin enzyme had a temperature optimum at 30�C but the sap enzyme had maximum PPO activity at 75�C. Both enzymes were relatively thermostable, requiring more than 15 min at 80�C for 50% loss of activity. It is concluded that browning of mango skin induced by the sap is predominantly catalysed by PPO in the skin and that this is unlikely to be prevented by heat treatment of the fruit.

Temperature-induced alanine oxidation in a psychrotrophic Pseudomonas

1975 ◽  
Vol 21 (12) ◽  
pp. 2028-2033
Author(s):  
Prince K. Zachariah ◽  
John Liston
Keyword(s):  
Heat Treatment ◽  
Enzyme Synthesis ◽  
Optimum Temperature ◽  
Temperature Optimum ◽  
Ph Optimum ◽  
Sephadex Column ◽  
Oxidase System ◽  
Psychrotrophic Bacteria ◽  
Induction Of Enzymes ◽  
Elution Fraction

A psychrotrophic pseudomonad isolated from iced fish oxidized alanine at temperatures close to 0 °C and grew over the range 0 °C–35 °C. The rate of oxidation of alanine, measured manometrically, by cells grown at 2 °C was lower than that of cells grown at 22 °C. However, the consumption of oxygen after heat treatment at 35 °C for 35 min was reduced considerably by 2 °C grown cells. Alanine oxidase activity was tested in an extract from cells grown at 2 °C and 22 °C with alanine as the sole carbon, nitrogen, and energy source. Cells grown at 2 °C produced an alanine oxidase with a temperature optimum of 35 °C and pH optimum of 8, which lost about 80% activity by heat treatment at 40 °C for 30 min. There was no change in activity after dialysis at pH 7, 8, or 9. Extracts from cells grown at 22 °C contained an alanine oxidase system with an optimum temperature of 45 °C, a pH optimum above 8, and only about 30% reduction of activity after heat treatment. This enzyme activity was concentrated in the 0.5 M elution fraction from a Sephadex column, and dialysis reduced the activity at pH 7 and 8. Mesophilic enzyme synthesis apparently started around a growth temperature of 10 °C.The crude alanine oxidase systems of Pseudomonas aeruginosa derived from cells grown at 13 °C and 37 °C had a common optimum temperature of 45 °C. These data suggest that one mechanism of psychrophilic growth by psychrotrophic bacteria may be the induction of enzymes with low optimum temperatures in response to low temperature conditions.

The role of polyphenol oxidase and peroxidase in the browning of water caltrop pericarp during heat treatment

2011 ◽  
Vol 127 (2) ◽  
pp. 523-527 ◽  
Author(s):  
Jhih-Ying Ciou ◽  
Hsin-Hung Lin ◽  
Po-Yuan Chiang ◽  
Chiun-C. Wang ◽  
Albert Linton Charles
Keyword(s):  
Heat Treatment ◽  
Polyphenol Oxidase

scholarly journals Insight of Polyphenol Oxidase Enzyme Inhibition and Total Polyphenol Recovery from Cocoa Beans

Antioxidants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 458 ◽  
Author(s):  
Said Toro-Uribe ◽  
Jhair Godoy-Chivatá ◽  
Arley René Villamizar-Jaimes ◽  
María de Jesús Perea-Flores ◽  
Luis J. López-Giraldo
Keyword(s):  
Heat Treatment ◽  
Polyphenol Oxidase ◽  
Morphological Changes ◽  
Safe Procedure ◽  
Total Polyphenol ◽  
Chemical Inhibitors ◽  
Oxidase Enzyme ◽  
New Equation ◽  
Full Factorial ◽  
Microscopy Images

A full factorial design (ascorbic acid/l-cysteine inhibitors, temperature, and time as factors) study was conducted to enhance inhibition of polyphenol oxidase (PPO) activity without decreasing cocoa polyphenol concentrations. The data obtained were modelled through a new equation, represented by Γ, which correlates both high polyphenol content with reduced specific PPO activity. At optimized values (70 mM inhibitory solution at 96 °C for 6.4 min, Γ = 11.6), 93.3% PPO inhibition and total polyphenol of 94.9 mg GAE/g were obtained. In addition, microscopy images confirmed the cell morphological changes measured as the fractal dimension and explained the possible cell lysis and denaturation as a result of heat treatment and chemical inhibitors. Results also showed that PPO enzyme was most suitable (higher vmax/Km ratio) for catechol, with a reduction in its affinity of 13.7-fold after the inhibition heat treatment. Overall, this work proposed a suitable and food-safe procedure for obtaining enriched polyphenol extract with low enzyme activity.

MANGO FRUIT SOFTENING RESPONSE TO POSTHARVEST HEAT TREATMENT

2006 ◽  
pp. 811-816 ◽  
Author(s):  
M.M. Benitez ◽  
A.L. Acedo Jr. ◽  
P. Jitareerat ◽  
S. Kanlavanarat
Keyword(s):  
Heat Treatment ◽  
Fruit Softening ◽  
Mango Fruit

scholarly journals (28) Lenticel Development and Discoloration of Some Mango [Mangiferaindica (L.)] Cultivars

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 995A-995
Author(s):  
Jan-Louis Bezuidenhout ◽  
Hannes Robbertse
Keyword(s):  
Polyphenol Oxidase ◽  
High Temperatures ◽  
Cell Walls ◽  
Economic Value ◽  
Extended Period ◽  
Cold Chain ◽  
Mango Fruit ◽  
Rough Handling ◽  
To Come ◽  
Fruit Surface

Discoloration of the lenticels of some mango cultivars is a serious problem, affecting the economic value of the fruit. Mango fruit lenticels develop from ruptured stomata on fruit from 20 mm in `TA' and `Keitt' and 30 to 40 mm in `Kent'. Lenticels enlarge as the fruit grow due to stretching of the fruit surface. Adult lenticels of `TA' and `Keitt' are larger in size than those of `Kent'. `Kent' lenticels are also better insulated than `TA' and `Keitt', having a thick cuticle in the lenticel cavity and, in some instances, a phellogen is also present where `TA' and `Keitt' lack both of the above mentioned. Resin present in the skin of the fruit play an important role in the discoloration of `TA' and `Keitt' lenticels. Resin of both `TA' and `Keitt' fruit contain a considerable amount of an aggressive compound termed terpenes. These terpenes are volatile and able to move out of the resin ducts via the sublenticellular cells to the outside of the fruit. The integrity of tonoplasts situated in sublenticellular cells are lost due to the presence of terpenes, causing vacuolar bound phenols to come into contact with polyphenol oxidase, present in the cell walls. The product of the resultant reaction is a quinone, accumulating as a brownish deposit in the cell walls, the black markings visible from the outside. This is the spontaneous discoloration process. Lenticel discoloration may also occur due to maltreatment, i.e., rough handling, to high temperatures, extended period on brushes on the packline, breaking of the cold chain, and spilling of resin onto the surface of the fruit.

scholarly journals EFFECTS OF VAPOR HEAT TREATMENT ON MANGO FRUIT QUALITY

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 678e-678
Author(s):  
Elizabeth J. Mitcham ◽  
Roy E. McDonald
Keyword(s):  
Heat Treatment ◽  
Heat Stress ◽  
Shelf Life ◽  
Fruit Quality ◽  
Electrolyte Leakage ◽  
Mango Fruit ◽  
Mild Heat ◽  
Control Fruit

Mature green mango (Mangifera indica L.) fruit were heated (100% RH) at 50C for 120, 180 or 240 min or 46C for 160, 220 or 280 min. The rate of mesocarp color (CIE a*) development was reduced in treated fruit, particularly in inner tissue. Rate of softening of mesocarp tissue was reduced after heat treatment; inner more than outer. Fruit treated at 50C remained more firm than control fruit 9 days after treatment, whereas fruit treated at 46C were more firm than controls 3 days after treatment, but were similar by 9 days. Electrolyte leakage from inner mesocarp tissue disks increased with increasing time at 50C, but was unchanged in fruit treated at 46C. However, after 3 days, electrolyte leakage returned to control levels. Ethylene-forming enzyme (EFE) activity of inner meso-carp tissue was greatly reduced in fruit treated at 50C (all times), and at 46C (220 and 280 min). After 3 days, EFE activity of fruit from most treatments had recovered to levels higher than controls. These data indicate that fruit may be able to recover from heat stress. Mild heat stress may increase postharvest shelf life by reducing the rate of softening.

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