Fruit ripening

Fruit Ripening Presentation

1. Fruit Ripening V. Siva Shankar 12-541-009 T NAU

2. Ripening Ripening is a process in fruits that makes it acceptable for consumption . The fruit becomes sweeter, and softer. During ripening starch is converted to sugar. The fruit is said to be ripe when it attains its full flavour and aroma ( watada et al ., 1984). Ripening causes colour change in the fruit. Based on ripening behaviour , fruits are classified as: Climacteric Non Climacteric

3. Fruits show dramatic increase in the rate of respiration during ripening and well respond to ethylene for ripening Climacteric Fruits Eg . Apple , Banana, Mango, Tomato

4. Fruits do not show dramatic increase in the rate of Respiration during ripening and do not respond to Ethylene for ripening Non - Climacteric Fruits Eg . Citrus , Grapes, Pineapple & Watermelon

5. unripe fruit produces H 2 C=CH 2 (ethylene) induces/turns on genes enzymes ripening fruit (for enzyme synthesis) producing degrade parts of fruit resulting in increasing (chlorophyll, acids, starches, pectin, proteins, etc.)

6. BIO SYNTHESIS -- ETHYLENE Methionine Adenosyl Methionine ACC Ethylene ACC Synthase ACC Oxidase O 2 Amino Cyclopropane Carboxylic acid AdoMet Synthetase ATP

7. Changes during ripening Cell wall Starch Organic acids Pigments Flavouring compounds Ascorbic acid Phenolics Amino acids and proteins Respiration Transpiration Ethylene evolution rate

8. Cell wall changes It is rich in polysaccharides are degraded and solubilised during ripening ( Jona and Foa , 1979). Loss of neutral sugars such as galactose and arabinose ( Tuker et al., 1987). Enzymes responsible for cell wall hydrolases Pectineasterase Polygalacturonase Cellulase β - galactosidase ( Tuker , 1993)

9. Starch Amylase degrades starch to sugar, hence the mealy quality to juiciness. Thus the starch is fully hydrolysed into sugars is known as characteristic event for fruit ripening ( Hulme , 1978). Starch degrading enzymes in fruits are α-amylase β - amylase Phosphorylase α- 1, 6-glucosidase (Garcia et al ., 1988)

10. Organic acids The total organic acids( malic + citric + quinic ) is decreased with ripening of fruits (Wang et al 1993). The decline in the content of organic acids during ripening is the result of an increase in membrane permeability ( kliewer , 1971). Pigments Degradation of chlorophyll pigment results in anthocyanins or carotenoids . Phenylalanine ammonia lyase and flavone synthase are the key enzymes for synthesis of anthocyanins (Tucker, 1993). Biosynthesis of carotenoids lycopene acts as the precursor of β - carotene.

11. Flavouring Compounds Interaction of sugars, organic acids, phenolics and volatile compounds. Esters, alcohols, aldehydes and ketones . Ascorbic acid Ascorbic acid is increase with fruit growth in pome , pear etc Thereafter the levels declined with the advancement of maturity and onset of fruit ripening (Sharma, 1995).

12. Respiration Respiration is the process by which stored organic materials (carbohydrates, proteins, fats) are broken down into simple end products with a release of energy. Respiration involves degradation of food reserves, especially sugars, in order to produce chemical energy (in the form of ATP and NADH) needed to maintain cellular metabolic activity.

13. Transpiration Water loss is a main cause for direct quantitative loss, appearance, textural quality, and nutritional quality. Transpiration is physical process that can be controlled by applying some treatments to the commodity. ( like waxes and other surface coating or wrapping with plastic films ).

14. Current Ripening Methods Calcium Carbide is widely using chemical to hasten the ripening. It contain traces of arsenic and phosphorus , these are toxic and may be hazardous to health. Calcium Carbide reacts with moisture in the air to produce acetylene gas . Acetylene gas acts as a ripening agent, but is believed to affect the nervous system by reducing supply of oxygen to the brain. It is banned under Rule 44-AA of PFA (Prevention of Food Adulteration) Rules, 1955.

15. Ripening with Artificial Ethylene Scientific and safe ripening method accepted worldwide. Ethylene is a natural plant hormone that the fruit itself emits as it ripens. Ethrel or ethaphon (2-chloroethane phosphonic acid). Exposure of unripe fruit to a miniscule dose of ethylene is sufficient to stimulate the natural ripening process until the fruit itself starts producing ethylene in large quantities. The use ethylene to promote ripening is permitted under FDA regulation 120,1016.

16. Ripe Fruit chemical cause The hormone ethylene initiates the ripening response: Unripe Fruit physical condition Green Hard Sour Mealy chlorophyll pectin acid starch chemical cause red soft neutral sweet + juicy physical condition anthocyanin less pectin neutral sugar hydrolase pectinase kinase amylase Enzyme Produced H 2 C=CH 2

17. The four major factors for commercial ripening Temperature control. RH control. Ethylene gas. Adequate air circulation.

18. Commercial Use of Ethylene • Methods of application – cylinders of ethylene or banana gas (C 2 H 4 in CO 2 ) with flow meters. – ethylene generators (liquid ethanol plus catalyst produces C 2 H 4 ) – ethylene-releasing chemicals (e.g. Ethephon = 2-chloroethanephosphonic acid)

19. Commercial Use of Ethylene • Ethylene concentration and duration of treatment: – physiological responses saturated at 100 ppm . – mature climacteric fruit should initiate endogenous ethylene production within no more than 72 hours. – degreening should continue for no more than 72 hours or risk increased peel senescence and decay.

20. Commercial Use of Ethylene • Ripening of climacteric fruits: – Banana – Tomato – Avocado – Mango – Papaya – Persimmon – Honeydew melon Banana ripening

21. Commercial Use of Ethylene Ripening of climacteric fruits: • Recommended conditions (tomatoes): – 20 to 21°C – 90 to 95% RH – 100 to 150 ppm C 2 H 4 – Air circulation = 1 m 3 per ton of product – Ventilation = 1 air change per 6 hours or open room for 0.5 h twice per day

22. Undesirable Ethylene Effects • Undesired ripening and softening of fruits in storage. • Accelerated senescence and loss of green color in immature fruit. • Sprouting (stimulation or retardation)

23. Overcoming Ethylene’s undesirable effects Eliminating sources of ethylene Ventilation Chemical removal

24. Control of Ripening Measure to control ripening helps to increase the shelf life of fruits . Temperature Regulation Rate of ripening increases with the increase in temperature. Storage at low temperature immediately after harvest reduces the rate of respiration and ethylene production. Storing in low temperature below optimum level results in cold injury and spoilage of fruit quality.

25. Regulation of storage atmosphere The natural atmospheric air is conductive for the synthesis of ethylene. Lowering oxygen content or increasing carbon- di -oxide concentration in the air within the storage cabinet retards ethylene production. Decreasing O 2 concentration below 5 per cent and increasing CO 2 concentration between 3 to 10 per cent delayed ripening by inhibiting ethylene. The shelf-life of fruits can thus be increased.

26. Chemical Regulators Potassium permanganate is a good ethylene absorbent. Using KMnO 4 coated newspaper as packing materials in the bottom delays ripening. Ethylene synthesis inhibitors (block synthesis of SAM→ ACC) AVG - A minoethoxy V inyl G lycine MVG - M ethoxy V inyl G lycine AOA - A mino O xyacetic A cid

27. Avoiding Exposure to Ethylene • Removal of ethylene from storage rooms: – use of adequate ventilation (air exchange) – use of ethylene absorbers • potassium permanganate (alkaline KMnO4 on inert pellets “Ethysorb,” etc.) • Activated and brominated charcoal +/- KMnO4 = “Stayfresh” absorbers

28. Avoiding Exposure to Ethylene • Removal of ethylene from storage rooms: – use of ozone or UV radiation to oxidize ethylene: 1. O 2 + UV → O 3 2. C 2 H 4 + [O] → → CO2 + H2O – must remove excess O 3 to avoid injury to fruits & vegetables

29. Inhibiting Ethylene Biosynthesis & Action Biosynthesis inhibition: AVG - A minoethoxy V inyl G lycine MVG - M ethoxy V inyl G lycine AOA - A mino O xyacetic A cid Inhibits ACS (i.e., SAM → ACC) • Action inhibition – 1-MCP (1-methylcyclopropene) • Irreversibly binds to ethylene receptors • “ EthylBloc ” and “ SmartFresh ”

30. 1-MCP (1-Methylcyclopropene) Cyclopropane derivative ( Cyclodextrin powder) Gaseous ethylene action inhibitor Non- toxic Odourless gas Binds irreversibly to ethylene receptor Simple organic compound(C 4 H 6 ) ( Sisler and Serek , 1999) Ethylene Action Blocker (ethylene→ block action)

31. 1-MCP Mode of Action 32 Works by tightly binding to the ethylene receptor site in fruit tissues, thereby blocking the effects of ethylene. Once ethylene production is prevented, It no longer promotes ripening and senescence . Blocking of ethylene receptor by 1-MCP gas causes fruits to be ripen and soften more slowly.

32. Application of 1-MCP EthylBloc ®(0.14%), SmartFresh ™( 3.3%), SmartTabs ™( 0.63%). When the product is mixed with water or a buffer solution, it releases the gas 1-MCP. Formulation Type: Powder Timing: Immediately after harvest.

33. Commercial products of 1-MCP EthyBloc ® – for use with ornamentals SmartFresh ® – for use with fruit and vegetables 34

34. Chemical : 1-MCP (0.6 µl l −1 ) Cultivars : ‘Cortland’ and ‘Empire’ apple Duration of exposure to of 1-MCP :0, 3, 6, 9, 12, 16, 24, or 48 h Temperature :3, 13, or 23 °C

35. Fruit firmness of ‘Cortland’ (A) and ‘Empire’ (B) apples exposed to 0.6 µl l −1 1-MCP for 0, 3, 6, 9, 12, 16, 24, or 48 h at 3, 13, or 23 °C, and stored 120 days in air at 0–1 °C.

36. Incidence of severe superficial scald development in ‘Cortland’ apples exposed to µl l −1 1-MCP for 0, 3, 6, 9,12, 16, 24, or 48 h at 3, 13, or 23 °C, and stored 120 days in air at 0–1 °C plus 7 days at 20 °C.

37. Conclusion The treatment temperature and duration are important factors that affect the effectiveness of 1-MCP on apple quality and different cultivars respond differently to 1-MCP treatment 1-MCP has tremendous potential for maintaining apple quality during storage, but its efficacy can be affected by treatment temperature and duration as well as by apple cultivar

38. Ethylene induced ionic leakage and water loss and peroxidase activity.

39. References