Maturity indices of fruits and vegetables

1. Topic : Maturity indices of fruits and vegetables SUBMITTED BY S. SHARVESH M.Sc (Hort.)Fruit science Annamalai university ANNAMALAI UNIVERSITY FACULTY OF AGRICULTURE DEPATMENT OF HORTICULTURE

2. Maturity indices of fruits and vegetables

3. IMPORTANCE Diverse agro-climatic regions enables cultivation of a number of fruits, and vegetables. India looses about 25 to 30% of the produce during post-harvest handling and mismatching harvest, with proper maturity of fruits plays a great role. In general, picking of immature fruits results in poor quality, lacking in flavour and taste, which shrivel during storage. Over mature fruits develop soft scald and internal breakdown with poor shelf life. Thus, harvesting of fruits at right maturity is essential to improve fruit quality and minimize post-harvest losses.

4. MATURITY It is the stage of fully development of tissue of fruit and vegetables only after which it will ripen normally During the process of maturation the fruit receives a regular supply of food material from the plant When mature, the abscission or corky layer which forms at the stem end stops this inflow Afterwards, the fruit depend on its own reserves

5. Horticultural maturity vs ripening Maturity may be defined as the attainment of a proper size after which ripening takes place. Ripening means the qualitative changes in fruits after maturity as a result of which it becomes edible.

6. In addition to this, typical flavour and characteristic colour also develop It has been determined that the stage of maturity at the time of picking influence the storage life and quality of fruit when picked immature like mango develop white patches or air pockets during ripening and lacking in normal brix acid ratio or sugar acid ratio, taste and flavor on the other hand if the fruits are harvested over mature or full ripe they are easy susceptible to microbial and physiological spoilage and their storage life is considerably reduce

7. Such fruits persist numerous problems during handling, storage and transportation Therefore, it is necessary or essential to pick up the fruits or vegetables at correct stage of maturity to facilitate proper ripening, distant transportation and maximum storage life The postharvest quality of the product is fixed at the harvest so proper harvesting is necessary We can have good harvest if we harvest at proper time as the development of the fruits is at later stage of development

8. Fruits harvested too early may lack flavor and may not ripen properly, deteriorate faster and have short shelf life while produce harvested too late may be fibrous or have very limited market life Yield may also be lower Therefore harvesting of fruits and vegetables at proper stage of maturity is of paramount importance for attaining desirable quality The maturity has been divided into two categories i.e. physiological maturity and horticultural maturity.

9. Horticultural maturity/Commercial maturity Stage of development when plant parts possess the necessary characteristics preferred by consumers Depends on the intended use e.g. papaya, jackfruit Physiological maturity Applies only to fruits and fruit vegetables End of development stage Ability to ripen normally after harvest for distant market and storage, climateric fruits should be harvested at maturity before they are ripe i.e. before climateric rise Non climateric fruits should be harvested at ripe stage

10. Importance of maturity indices Maturity indices = harvest indices Sensory and nutritional quality Adequate shelf life Facilitate marketing- standards Productivity

11. Too often we are on the side of shelf life at the expanse of good eating quality

12. Maturity indices Sign or indications of the readiness for harvest Basis for determining harvest date Two types of maturity indices i ) Subjective: Qualitative Use the senses (color, size, shape, sound, firmness, juice content etc.) ii) Objective: Quantitative Are measurable indices (TSS, TA, Starch content, oil content, firmness, dry matter, Days after full bloom, heat degree day, respiration and ethylene production, production of volatiles etc.)

13. Types of indices i ) Visual indices a) Size and shape: Maturity of fruits can be assessed by their final shape and size at the time of harvest. Fruit shape may be used in some instances to decide maturity. For example, the fullness of cheeks adjacent to pedicel may be used as a guide to maturity of mango Banana : angular shape changes to round

14. b) Colour : The loss of green color of many fruits is a valuable guide to maturity

15. ii) Physical indices a) Firmness: As fruit mature and ripen they soften by dissolution of the middle lamella of the cell walls. In many fruits such as apple, pear, peach, plum, guava, kinnow etc. firmness can be used to determine harvest maturity. Penetrometer measures the pressure necessary to force a plunger of specified size into the pulp of the fruit. Such pressure is measured in pounds and kilograms force.

16. b) Specific gravity: Specific gravity is the ratio of the density of a substance to the density of a reference substance. As fruit mature, their specific gravity increases. This parameter is rarely used in practice to determine when to harvest a crop It is used to grade crops into different maturities. To do this the fruit or vegetable is placed in a tank of water; those that float will be less mature that those that sink. In practice, the fruit or vegetable is weighed in air, then in pure water. The weight in air divided by the weight in water gives the specific gravity .

17. iii) Chemical Measurement The total soluble solids of the fruit can be measured with refractometer , which indicate the harvest maturity of fruits. Acidity is readily determined on a sample of extracted juice by titration with 0.1 N NaOH . TSS/TA is better to judge maturity as it gives the sugar acid blending of product a) Total Soluble Solids can be determined in a small sample of fruit juice using hand refractometer The refractometer measures the refractive index, which indicates how much a light beam will be slowed down when it passes through the fruit juice. The refractometer has different scales (0-32 O B), (28-62 O B) and (56-92 O B) which can be read directly.

18. For large size fruits, these should be cut from stem to blossom end and to the centre of the fruit to account for variability in TSS from top to bottom and inside to outside of the fruit. The fruit tissues should be macerated thoroughly in pastle motor and then from the mescerated pulp the juice is extracted by passing through muslin cloth. A drop of juice is then put on the prism of the refractometer and TSS content can be read directly on the scale. However, in case of small fruits like grapes, the juice content can be extracted by simply pressing the whole fruit.

19. b) Titratable acidity: Titratable acidity (TA) can be determined by titrating a know volume of juice with 0.1N NaOH to end point The milliliters of NaOH needed are used to calculate the TA. The TA expressed as percent malic , citric or tartaric acid can be calculated as follows:

20. iv) Calculated indices: a) Calendar Date/Days after full bloom : Useful guide to harvest, where seasonal variation in climate is small This method works well when the blooming period is short period b) Heat Units: It has been found that a characteristics number of heat unit or degree-days is required to mature a crop under usually warm conditions It is based on the principle that growth of plant organ is directly proportional with ambient temperature

21. V) Physiological Method: Respiration rate: Particularly on climateric fruits can accurately pin point the most appropriate time of harvest as there is climateric rise in respiration Internal ethylene evolution: Like respiration rise climateric fruits also have ethylene peak Volatiles production: Apple: Ethyl-2-methyl butyrate Banana: Eugenol Grapefruit: Nootaketone Lemon: Citral Orange: Valencene

22. Maturity indices should be simple, easy to carry out Objective vs subjective indicators Related to quality Related to storage life Represents a progressive change with maturity Premits prediction of maturity from year to year inexpensive

23. Limitations of maturity indices uses Soil conditions, nutrition, irrigation Season , climate Position on the plant Pruning and other cultural practices and management practices varieties

24. Maturity (Commercial or Horticultural maturity) : refers to the stage at which the produce is optimally accepted to the consumer. Maturity index : The maturity at harvest determines the quality and post- harvest shelf-life of the fresh fruits. The study of maturity indices helps to harvest the crop at right time. Judging maturity : There are various means of judging maturity but they vary according to the kind of fruits, local soil and climatic conditions, but generally farmers follow visual means (appearance). But this is not a perfect method, many a times it may mislead the farmers. There are certain limitations for all maturity indices due to variation in nutrition of the crop, fruit shape, size, climate, seasonal factors, moisture, pruning method, use of hormones and other chemicals. We can use various indices to judge maturity.

25. MANGO Slight colour development on the shoulders. When one or two ripe fruits fall from the tree naturally ( tapka method). Skin colour changes from dark green to olive green. Counting of the days from fruit set to maturity. When the specific gravity of fruits ranges between 1.01 to 1.02. Flesh firmness

26. Lenticels become more prominent and waxy bloom gradually disappears. When the TSS reaches 1 1-15 o Brix . The first and second methods are not of much help since these are not representative of the fruit maturity of the entire tree and the fruits harvested do not ripe uniformly.

27. MANGO Change in peel colour on the shoulders.   ii. Falling down of some ripe fruits from the tree ( tapka ).   iii. Specific gravity of most of the fruits reaching between 1.01 and 1.02.   iv. Number of days taken by the fruit to mature

28. The fruits are harvested at different maturity level based on distance of transport. For long distance transport 75-80% maturity and for short distance transport 90-100% maturity fruits can be harvested. 1. When the pulp peel ratio reaches 1.2 - 1.6. 2. Days taken from shooting, i.e., 3.0-3.5 months. 3. Disappearance of angularity of the fingers. 4. Brittleness of floral ends. 5. Drying of leaves in some varieties. BANANA

29. Bananas are harvested while fully mature but green and transported to the markets, where these are ripened artificially under controlled conditions. For local markets, the banana should be harvested when the ridges on the surface change from angular to round. Fall of floral remnants, pulp to peel ratio (10 :1), pH of fruit (5.2-5.6) etc. are also good harvest indices in banana.

30. GUAVA Guava fruits generally take about 17-20 weeks from fruit set to reach maturity. When the colour changes from dark green to light green. When the specific gravity is one (1.0).

31.   Guava is consumed at different stages of fruit growth and development.   The recommended optimum stage for harvesting is about 2-3 weeks before attaining full growth.   Peel and pulp texture, peel colour , sugar and tannin contents, TSS and titratable acidity, may also be adopted as maturity indices

32. GRAPE Grape is harvested when they reach a TSS of 16 to 24% depending on variety. Bangalore blue : 12-14% Anab -e- Shahi and Selection – 7 : 16-18% Thompson seedless : 20-22%

33. Besides TSS, the following physical characteristics are also useful in judging maturity. Texture of pulp (softness) Peel colour (light yellow) Easy separation of the berries from the bunch Development of characteristic flavor and aroma.

34. Grapes ripen only on the vine, so ripening standards are practically applicable for harvesting. Grapes are considered ripe when the fruits have reached the condition of accumulation of sugar and acid contents, which are the best suited for intended use. At harvest, the berries should have attained attractive appearance, good eating and keeping quality and TSS/acid ratio. Heat units are other useful criteria for predicting maturity in grapes .

35. PAPAYA For local market: When skin colour changes at the apical end of the fruit. For long distance transport: When the skin colour changes from green to yellow to the extent of 6%. When the latex of the fruit becomes almost watery.

36. Maturity identification to ensure adequate fruit ripening and good eating quality- major problem For local markets, half-yellow fruits should be harvested. Fruits can also be harvested at the appearance of yellow streaks on the dark green surface. Softness to touch, seed colour , jellyness of seed and the change in latex colour (from white to watery): Other indices

37. PINEAPPLE For local market: When 25% of surface changes to yellow colour . For long distance: When all the eyes are still green and have no trace of yellow colour (75-80% maturity) In India: 1. Pineapples are harvested when the colour changes from green to greenish yellow. 2 The fruit develops a smooth surface around the eyes.

38. 3. The flattening of eyes. 4. TSS : acid ratio of 21 to 27 and specific gravity of 0.98 to 1.02.

39. JACK FRUIT A dull, hollow sound is produced when the fruit is tapped by the finger. The last leaf of peduncle turns to yellow. Fruit spines become well developed and widely spaced. An aromatic odour develops.

40. JACK FRUIT

41. POMEGRANATE The fruits are ready for harvest between 135-170 days after anthesis . The fruit colour changes in summer to dark yellow and in winter to dark red. The persistent calyx at the anterior end of the fruit curves inward and become hard and dry at maturity. Rind is very hard

42. Days after pollination, peel colour and TSS: acid ratio good maturity indices Fruits are harvested between 135 to 170 days after anthesis . When their peel turns slightly yellow (summer) or red (winter). Fruits give a metallic sound when tapped. The properly mature fruits are easily scratched with a finger nail. The TSS:acid ratio ( 70:1)

43. SAPOTA The peel shows a dull orange or potato colour with a yellowish tinge when scraped. The scurf content on the surface of the fruit will be minimum and easily fall off. The content of milky latex drops to almost zero.

44. Fruits dull orange or potato in colour . Fruit show light yellow streak after scratching instead of a green streak, which is a sign of immature condition .   Disappearance of brown scaly material from the fruit surface.   Dropping of the milky latex content almost to zero.   Falling of the dried spine like stigma at the tip of the fruit automatically or by touch.

45. CITRUS Maturity indices differ among the citrus species/varieties. Mandarins : When the rind colour changes from green to orange colour . Sweet orange: When the rind colour turns to yellow.

46. Development of proper colour , TSS:acid ratio are the best maturity indices. The preferred sugar:acid ratio for sweet oranges is 8.5 to 8.9 and for mandarins between 10.5 to 13.0. For Kinnow mandarin, this ratio should be between 12.1 to 14.1. In Kinnow , colour break occurs much before the maturity, the TSS/acid ratio (12:1 to 14:1) should therefore, be taken as index of maturity.

47. Limes: When the rind colour changes to light green to yellow colour . The International Standards Organization has set in minimum juice content of citrus as follows. Washington Navel Oranges 30% Other orange varieties 35% Grape fruit 35% Mandarin orange 33% Lemons and limes 25% For processing total juice content of the fruit is important.

48. FIG When fruits become soft and wilt at neck. Fruits hanging down from their own weight. No milk exudation from the stem when the fruit is pulled off.

49. CUSTARD APPLE When the fruit turns to light green colour . Development of yellowish white colour between the carpels . Initiation of widening the gap between carpels or segments.

50. BER Attainment of full size of particular cultivar with softening of pulp. Development of characteristic yellow or golden yellow colour . Days to mature the fruits. Ex: In Delhi cv. Gola took only 150 days where as Tikadi requires 173 days to mature. In cultivars like Gola , kaithli and umran , there was an increase in reducing and non-reducing sugars, total sugars and TSS.

51. BER Change in fruit colour from green to pale, titratable acidity, total soluble solids and specific gravity of the fruit are the maturity indices for ber .

52. DATE PALM Sl. No. Stage Characteristics 1 Doka ( khalal ) Fruit becomes hard, yellow or pink or red, TSS- 30 to 45%, astringency present or absent depending o cultivar, Edible stage. 2 Dang (rutab) Softness starting at tip of fruit, tannins and astringency disappears, lose weight and moisture content is about 35 – 40%, Edible stage. 3 Pind (tamur) Fully ripe fruit, lose weight, TSS- 60 to 84 %, Edible stage. It can be harvested at 3 different stages.

53. The dates are eaten at different stages of maturity, depending upon the variety. In general, dates are harvested at dang stage of maturity, when the fruits start softening. In India, dang stage is never reached due to pre-monsoon showers and hence these are harvested at doka stage, when the colour of fruit starts changing to pink and the astringency decreases significantly.

54. LITCHI Flatness of tubercles and comparative smoothness of epicarp change in pericarp colour is the most commonly used as harvesting index. Brix:acid ratio (70:1) is adopted internationally as the commercial maturity standard for litchi

55. APPLE Apple is a climacteric fruit and thus maturity of fruit does not coincide with the ripening. Picking of immature fruits results in poor quality, lacking in flavour and taste, which shrivel during storage. Over mature fruits develop soft scald and internal breakdown with poor shelf life. TSS, ease in separation of fruit from the spur, change in colour from green to pale or red , fruit firmness and DFFB harvest: some reliable maturity indices Iodine test

56. STRAWBERRY For local markets, fruits are usually harvested when 2/3 rd to 3/4 th part of berries has attained red colour . For distant markets, berries are sometimes harvested when colour development has just initiated and berries are hard.

57. PEACHES AND PLUMS Days from full bloom to maturity is the best maturity index for peaches and plums. Fruit size, firmness, sense of touch, ground colour , sugars, acidity, sugar:acid ratio etc., have been assessed, can be used as maturity index for harvesting peaches and plums.

58. ANOLA The colour of the fruit is the most reliable harvesting index in aonla . The fruits are normally light green but on maturity and ripening, the colour becomes dull, greenish yellow or rarely brick red. Vitamin C content can also be taken as a reliable maturity index.

59. MATURITY OF VEGETABLES Physiological maturity is the stage of development when maximum growth and maturation Commercial horticultural maturity is the stage of development required by the market. Maturity at harvest affect its marketability and storage life, nutritional content, freshness, flavor Over mature vegetables will be stringy and coarse.

60. Harvest criteria according to edible plant part Fruit vegetables   Immature fruit Tender, easily damaged (Legumes, cucumber­ber , squashes, eggplant, peppers, okra).   Harvesting is primarily based on size and color. Maturity is not a real problem un­less the harvest is delayed too long and they become over mature.   Mature fruit (Muskmelon, watermelon, pumpkins, tomatoes, ripe peppers). Harvest index depends on several characteristics and is dependent on the vegetable. Consumed at ripe stage, continue to increase in eating quality if allowed to fully ripen on plant, but little shelf or storage life

61. Leafy vegetables Quality and shelf life are better if harvested slightly immature. The determination of horticultural maturity varies with the commodity, but generally size is the principal criterion. Floral vegetables Hand harvested. Head size and development determine maturity of floral vegetables. Floral vegetables include artichoke, broccoli, and cauliflower. Roots, tubers, and bulb vegetables Maturity indices vary with commodity. Many of these products can be harvested and marketed at various stages of development.

62. Maturity indices for specific vegetables

63. CAULIFLOWER Sunlight is excluded (blanched) when the curds of the cauliflower are 1 to 2 in. in diameter by loosely tying together the outer leaves above the curd (head) with a string or rubber band. The curds are harvested when they are 4 to 8 in. in diameter and compact, white, and smooth. The head should be ready 10 to 15 days after tying .

64. CABBAGE Cabbage heads are harvested when the heads feel hard and solid but before they split . The outer leaves should be uniform green or purple color (depending on type

65. BRUSSELS SPROUTS When sprouts are 1 to 1½ inch in diameter and firm. Lower leaves along the stem are often remove to hasten maturity

66. BROCCOLI Head is dark green with a compact cluster (about 6 in. in diameter) of tight flower buds Before any yellow flowers appear. The head is cut 6 to 7 in. below flower heads.

67. TOMATOES Tomato fruits are harvested at the required ripeness stage for marketing or consuming, from mature green to fully red stage

68. EGGPLANT Eggplants are harvested when the fruits are 6 to 8 in. in diameter and their color is a glossy purplish black or white (depending on cultivar). As eggplant fruits get older they become dull colored, soft, and seedy.

69. BEANS Beans are harvested when the pods are filled with the enlarged seeds. The harvested pods must be green and not show any signs of becoming yellowish.

70. OKRA Okra pods are harvested when they are 3 to 5 in. long and tender. They generally harvested at least every other day during the peak growing season. Over mature pods become woody and are too tough to eat.

71. ONIONS Bulb onions are harvested when the tops fall over and begin to turn red/white yellow . Ideal bulb onion diameter is 2 to 4 in. Onions are dug and allowed 1 dry out in the open sun for a few days to toughen the skin . The dried soil of the bulbs is removed by a gentle brushing. The stems are cut, leaving 2 to 3 attached to the bulb.

72. PEAS Edible- podded cultivars of peas are harvested when pods are fully developed (about 3 in.) but before seeds are more than one-half of their full size. Regular peas are harvested when the pods are well rounded and they are fully developed but still fresh and bright green.

73. PEPPERS Sweet peppers are harvested when the fruits are firm, crisp, and full-­sized (about 4 to 5 in. long). Green peppers will turn red or yellow (depending on the cultivar) if left on the plant. Hot peppers are allowed to attain their bright red color and full flavors while attached to the plant before they are cut and dried.

74. POTATOES Potatoes are harvested at any size greater than 2 to 3 inches in diameter. For full season potatoes, the tubers are harvested when the plants begin to yellow and die down . Exposure of tubers to sunlight is avoided or the tubers will turn green and become non-edible.

75. PUMPKINS Pumpkins and winter squash are harvested when they are full size The rind should be firm and glossy and the bottom of the fruit (or ground spot) is cream to orange. The rind is tough and resists puncture from a thumbnail. A 3- to 4-in. portion of stem is left attached to the fruit.

76. CUCUMBERS Cucumbers are harvested when the fruits are bright deep green , before any yellow colour appears. The length of the fruit should be 2 to 3 inches

77. SQUASHES Summer squash is harvested when the fruit is soft. Long-fruited cultivars are harvested when 1% inch in diameter and 4 to 8 inch long. Winter squash is harvested when the fruit is mature. Mature fruit are firm and glossy and not easily punctured by a thumbnail. The portion of the fruit that contacts the soil is cream to orange when mature.

78. WATERMELONS Watermelon fruits are harvested when they are ripe. Ripe watermelons produce a dull sound rather than a sharp, metallic sound when thumped. Other indicators are a deep yellow rather than white color where the melon touches the ground (ground spot), brown tendrils on the stem near the fruit, and a rough, slightly ridged feel to the skin surface .

79. MUSKMELONS Muskmelons are harvested when the stem slips easily from the fruit with a gentle tug . Another indicator of ripeness for certain cultivars is when the netting on skin becomes rounded and the flesh between the netting turns from a green to a tan color.

80. CARROTS Carrots are harvested when the roots are 1 in. in diameter. The largest roots generally have the darkest tops.

81. TURNIPS Turnip roots are harvested when they are 2 to 3 in. in diameter The tops can be used as greens when the leaves are 3 to 5 in. long.

82. RADISHES Radishes are harvested when the roots reach 1 inch in diameter (Indian and Chinese radishes grow much larger). The shoulders of radish roots often appear through the soil surface when they are mature. If left in the ground too long they will become tough and woody.

83. SPINACH Spinach is harvested by cutting all the leaves off at the base of the plant, when they are 4 to 6 in. long. Alternately, the entire plant may be harvested