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Lecture 3: Fruits and Vegetables Harvesting


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A lecture on Fruits and Vegetables Harvesting

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Lecture 3: Fruits and Vegetables Harvesting

  2. 2. LEARNING OBJECTIVES At the end of the lesson, the learners are expected to: 1. enumerate the various postharvest procedures; 2. define maturity index; 3. determine the maturity indices of common fruits and vegetables; 4. discuss the importance of maturity indices in postharvest handling; 5. differentiate physiological from horticultural maturity; and 6. enumerate the different harvesting practices of common fruits and vegetables;
  3. 3. LESSON OUTLINE 1.Procedures in Postharvest Handling of Fresh Fruits and Vegetables 2. Definition of Maturity Index 3. Maturity Indices of Common Fruits and Vegetables 4. Importance of Maturity Indices in Postharvest Handling 5. Differences between Physiological and Horticultural Maturity; and 6. Harvesting Practices for Common Fruits and Vegetables
  4. 4. Presentation 3.2 OtherOther treatmentstreatments Pre-coolingPre-cooling DryingDrying Selection,Selection, cleaning andcleaning and disinfectiondisinfection ReceptionReception GradingGrading Packing andPacking and packagingpackaging StorageStorage TransportTransport HarvestingHarvesting
  5. 5. In postharvest physiology, maturity is considered as "that stage at which a commodity has reached a sufficient stage of development that after harvesting and postharvest handling, its quality will be at least the minimum acceptable to the ultimate consumer" (Reid, 1992). Definition of Maturity
  6. 6. Fruit and vegetable quality is a combination of attributes and properties that give them value in terms of human consumption. Growers and shippers are concerned that their commodities have good appearance and few visual defects. To receivers and distributors, firmness and a long storage life are of keen importance
  7. 7. The optimum maturity at harvest is a very important determinant to the final quality of the product. For example: Fruits and vegetables picked too early or too late in season are more susceptible to physiological disorder and have a shorter storage- life than those picked at the proper maturity. Fruits picked immature may not fully ripen.
  8. 8. Maturity indices are used to determine maturity, to predict harvest date and to assess quality of crop, for example is the crop suitable for fresh or processed market. Based upon a range of physical and chemical properties of the crop ideally maturity indices should be simple to use and be non- destructive Maturity indices
  9. 9. Maturity indices require sets of quantifiable guidelines for determining maturity and quality of horticultural crop.
  10. 10. Practical uses of Maturity Indices 1) Export markets often include a guide for minimum and maximum maturity that is acceptable for a given commodity
  11. 11. 2) Marketing strategies to obtain premium prices for commodities “Supply and demand” delaying or expediting harvesting and shipping of a particular crop at the beginning or end of the season requires a measure of maturity if quality is to be maintained
  12. 12. 3) Efficient use of labor. A measure of maturity is important for organizing start and end dates for harvesting to ensure labor and equipment availability and reduce harvesting costs
  13. 13. Physiological maturity versus horticultural maturity Plant (part) has completed natural growth and development Certain stage of development so that upon harvesting from the plant commodity will continue to develop as if still on plant Quality has reached minimum acceptable standards Physiological maturity
  14. 14. Stage of development when a plant possess the quality prerequisites for use by consumers for a particular purpose. Commodity can be horticulturally mature at any stage of development or physiological maturity Horticultural maturity
  15. 15. All plant (parts) are harvested when horticulturally mature but may be physiologically immature or mature Examples of mature hort. / immature phys. crops: sweet corn, peas, snap beans, summer squash, cucumber and bean sprouts Examples of mature hort. / mature phys. crops: winter squash, melons, tomato, pepper Horticultural maturity
  16. 16. Types of maturity indices Age-related 1) Number of days from planting to maturity 2) Days from full bloom to harvest
  17. 17. Types of maturity indices Physical properties External and internal color; useful for many horticultural products Color charts produced for many commodities Measuring fruit surface color using a colorimeter
  18. 18. Size; May not be a good indicator of maturity as can be influenced by many factors but useful for peas, beans, potatoes, celery
  19. 19. Physical properties Shape; Some crops are harvested when reaching a certain shape. For example banana (3/4 full, full ¾ and round full), cucumber
  20. 20. Solidity- head lettuce and cabbage are harvested on the basis of the solidity of the head
  21. 21. Texture - 1) Firmness - (apples, pears, peaches) used to determine harvest date and to evaluate quality 2) Tenderness - measured with tenderometer - peas
  22. 22. 1) Development of an abscission layer – muskmelons 2) Development of a waxy layer on the epidermis – plums, grapes, honey dew melons 3) Development of netting on the surface – muskmelons 4) Internal structure - formation of gel-like material surrounding the seeds of tomatoes 5) Prior to tip opening - asparagus Morphological changes
  23. 23. Development of an abscission layer in cantaloupes
  24. 24. Locular gel formation in tomato
  25. 25. Tip opening in asparagus
  26. 26. 1) Starch - apples, pears 2) Soluble solids /Sugars - apples, pears, stone fruits, grapes 3) Acids; sugar/acid ratio – citrus, pomegranates, kiwifruit 4) Juice content - citrus fruits 5) Per cent dry weight- avocado 6) Astringency –persimmon, dates –low levels desirable 7) Ethylene production – apples, pears (particularly those destined for long term storage) Chemical composition
  27. 27. Starch content in apples particularly useful for green apples eg. Granny Smith
  28. 28. Measurement of soluble solids (°Brix) Refractometer An optical instrument that is used to determine the refractive index of a substance. Can be used to determine the identity of an unknown substance based on its refractive index to assess the purity of a particular substance, or to determine the concentration of one substance dissolved in another. Degrees Brix (symbol °Bx) is a measurement of the mass ratio of dissolved sucrose to water in a liquid. It is measured with a refractometer. A 25 °Bx solution is 25% (w/w). Minimum maturity index: NZ kiwifruit 6.25 % Passion fruit 14 – 18 % Cantaloupe (U.S. Fancy) 11 % Cantaloupe (U.S. No. 1) 9 % Quality index
  29. 29. Non-destructive maturity analysis Electronic Nose Used to detect aroma volatiles in a range of food types. Has been used for determining fruit maturity based on the production of aroma volatiles. Statistical analysis must be performed to interpret data. Most research literature is based upon method verification and comparing data with more established methods of evaluating maturity. Acoustic firmness sensor Method taps the fruit and then “listens” for vibrations (resonance attenuated vibration). Fruit of different maturities produce different vibration profiles. Measures whole product not just a restricted area. (
  30. 30. Non-destructive maturity analysis Spectroscopic analysis Various different methods based upon the interaction of atoms or molecules with the electromagnetic spectrum. 1)Visible spectral imaging (380 – 770 nm). Measuring surface color based on absorption of light energy by reactive groups in chlorophylls, carotenoids and anthocyanins. Used in packing lines to detect color of apples and peaches. 2)Fluorescence imaging Achieved by measuring electromagnetic radiation in the visible range following excitation with short wavelength radiation. Greatest use of application is in the measurement of chlorophyll fluorescence.
  31. 31. Non-destructive maturity analysis Near infrared spectrophotometry (NIRS) (750 nm – 2500 nm) Suitable for measuring compounds containing OH-, CH- and NH- groups. Extensively used in the food industry. Can be used to measure firmness, acidity, brix and color of fruits. Commercial packing line machines are Available (10 pieces fruit per second) and handheld machines are being developed. NMR and MRI imaging Abbott 1999 Postharvest Biology and technology 15: 207-225 Can be used but equipment is sophisticated and expensive and speed is too slow for commercial applications
  32. 32. The definition of maturity as the stage of development giving minimum acceptable quality to the ultimate consumer implies measurable points in the commodity's development, and the need for techniques to measure maturity. Why we need maturity indices
  33. 33. The maturity index for a commodity is a measurement or measurements that can be used to determine whether a particular commodity is mature. These indices are important to trade regulation, marketing strategy and to the efficient use of labor and resources.
  34. 34. Maturity at harvest is the most important factor that determines storage-life and final fruit quality. Immature fruits are more subject to shrivelling and mechanical damage, and are of inferior flavour quality when ripe. Overripe fruits are likely to become soft and mealy with insipid flavour soon after harvest.
  35. 35. Fruits picked either too early or too late in their season are more susceptible to postharvest physiological disorders than fruits picked at the proper maturity.
  36. 36. All fruits, with a few exceptions (such as pears, avocados, and bananas), reach their best eating quality when allowed to ripen on the plant. However, some fruits are usually picked mature but unripe so that they can withstand the postharvest handling system when shipped long-distance.
  37. 37. Most currently used maturity indices are based on a compromise between those indices that would ensure the best eating quality to the consumer and those that provide the needed flexibility in marketing.
  38. 38. Fruits can be divided into two groups: 1)fruits that are not capable of continuing their ripening process once removed from the plant, 2) fruits that can be harvested mature and ripened off the plant. Group 1 includes duhat, watermelon, rambutan, durian, lanzones, caimito, mabolo,aratiles, camachile,cherry, citrus fruits, grape, lychee, pineapple, pomegranate, guava and tamarind Group 2 includes apple, langka, avocado, banana, cherimoya, kiwifruit, mango, nectarine, papaya, dragon fruit, pear, peach, persimmon, plum, tiesa, chico, sapote.
  39. 39. Group 1 fruits produce very small quantities of ethylene and do not respond to ethylene treatment except in terms of degreening (removal of chlorophyll); these should be picked when fully-ripe to ensure good flavour quality. Group 2 fruits produce much larger quantities of ethylene in association with their ripening, and exposure to ethylene will result in faster and more uniform ripening.
  40. 40. Harvest Indices The quality of fruits and vegetable cannot be improved but it can be presented when harvesting is done at proper stage of maturity.
  41. 41. Harvest Indices The quality of fruits and vegetable cannot be improved but it can be presented when harvesting is done at proper stage of maturity. Immature fruits when harvested will give poor quality and erratic ripening.
  42. 42. In some cases, if the produce is to be shipped to distant markets, or stored, to wait for a better price, it should be picked in the mature but unripe stage. Here lies the difficulty, because unlike the ripening stage, the boundary between pre maturation and maturation stage is hard to detect. No prominent changes in firmness or colour are evident often harvest indices becomes arbitrary and subjective.
  43. 43. Maturity can be described as the attainment of the particular size or stage after which ripening takes place. On the other hand, ripening means the qualitative changes in fruits after maturity of which it become edible.
  44. 44. i) Number of days from fruit set, ii) Visual indicators, iii) Size of fruits, iv) Shape of fruit, v) Colour of fruit, vi) Appearance (External) vii) Texture viii) Lenticel number ix) Specific gravity x) Starch Content xi) Soluble solids xii) Sugar acid ratio xiii) Oil content xiv) Odor Various Maturity Indices are:
  45. 45. There are five types of indices to judge the maturity of the fruit. 1. Visual means 2. Physical means 3. Chemical analysis 4. Computation 5. Physiological method.
  46. 46. Types of Maturity of Fruits and Vegetables A) Harvesting Maturity B) Physiological Maturity C) Commercial or Horticultural Maturity
  47. 47. Harvesting Maturity: The harvest maturity of vegetable depends upon the purposes for which it is harvested. For local market and for processing, fully coloured tomato fruits are harvested.
  48. 48. However, for a distant market fruit which have started developing colour are harvested. The post-harvest quality and storage life of fruit appear to be controlled by the maturity. If the fruits are harvested at a proper stage of the maturity the quality of fruit is excellent.
  49. 49. The post-harvest quality and storage life of fruit appear to be controlled by the maturity. If the fruits are harvested at a proper stage of the maturity the quality of fruit is excellent.
  50. 50. Poor quality and uneven ripening are caused by early harvesting and late harvesting result in extremely poor shelf life. It is imperative that the fruit should be at the right stage of the maturity with no physical damage.
  51. 51. Various Maturity Indices such as number of damage from fruit set, visual indicators, size, shape, colour, appearances, texture, lenticel number, specific gravity starch contain soluble solids, sugar, acid ratio and oil content are used to determine maturity of fruits.
  52. 52. Commercial or Horticultural Maturity: It is a stage of fruit and vegetable at which consumer wants the fruit and vegetable or fruit and vegetable require by market. The horticultural maturity of fruits and vegetables depends upon the purpose for which it is harvested. Example: The okra pod is matured when it is tender with maximum size, as per horticultural maturity.
  53. 53. 2. It is a stage between development and growth of any plant part. 3. It can be predicted by using different terminology like premature, mature and over mature. 4. There is no necessity of senescence.
  54. 54. Harvesting is one of the important operations, that decide the quality as well as storage life of produce and helps in preventing huge losses of fruits. Harvesting of fruits should be done at optimum stage of maturity Harvesting of Fruits and Vegetables
  55. 55. During harvesting operation, a high standard of field hygiene should be maintained. It should be done carefully at proper time without damaging the fruits.
  56. 56. The harvesting operation includes. i) Identification and judging the maturity of fruits. ii) Selection of mature fruits. iii) Detaching or separating of the fruits from tree, and iv) Collection of matured fruits.
  57. 57. Method of Harvesting: Different kinds of fruit and vegetables require different methods after harvesting. The methods of harvesting are: 1.Manual Harvesting 2. Mechanical Harvesting
  58. 58. Manual Harvesting Harvesting by one’s own hand is called manual harvesting. It is done in several ways: a. Ladder / bag picking method b. Poles/ Clippers method c. Harvesting by means of cutting knives d. Harvesting by means of digging tools.
  59. 59. 2. Mechanical Harvesting: In this method numbers of mechanical devices are used for harvesting the produce on commercial scale.
  60. 60. Presentation 3.2 • inappropriate maturity at harvest (over ripening increases sensitivity to quality decay ; immature fruits market rejection). • inappropriate harvest technique (mechanical damages-physical injuries). • climatic conditions at harvesting (free water, exposition of product to direct sun light ) • harvesting wet products (increase sensitivity to quality decay) • inappropriate harvesting containers ( physical injuries). HarvestingHarvesting Associated hazardsAssociated hazards
  61. 61. Presentation 3.2 RecommendationsRecommendations • training personnel on optimum maturity indices. • Application of appropriate maturity indices based on: external quality color, consistence, phenological stage, etc. • Harvesting time: early in the morning or late in the afternoon in order to minimize the sun effect. • Optimizing harvesting recipes/containers (size, materials, height, number of produce layers, conditions, etc. ) • protection of product of direct sun intensity.