maturity indices of pineapple

A.J

1. MATURITY INDICES OF PINEAPPLE

2. COMPUTATIONAL METHODS Calendar Days 110-146 days after the date of flowering

3. PHYSICAL METHODS Fruitlet Flatness The pineapple has numerous individual fruitlets, which mature from the bottom part of the fruit to the top. As the fruitlets mature, they become flatter. A pineapple is typically mature and ready for harvest when the lower one-quarter to one-half of the fruitlets are flat.

4. Fruit Surface Colour Pineapples change from green to yellow to reddish-brown as they mature. Pineapples are considered ripe and at their best eating quality when the fruit surface colour is the one-quarter to one-half yellow . The fruit will also bruise easily and is more vulnerable to damage. Pineapples are over-mature when the surface colour of the fruit changes to reddish-brown. The following colour classification, or peel-colour index, may be used in trade: C0 – Totally green exterior C1 – Beginning to turn yellow/orange on one quarter of the fruit surface C2 – Yellow/orange on one half of the fruit surface C3 – Yellow/orange on two thirds of the fruit surface C4 – Totally orange/yellow fruit.

5. Internal Appearance Random samples of fruit should be sliced horizontally at the point of the largest width. Immature pineapple fruit have a white flesh colour, and are slightly clear in appearance while mature or ripe fruit have a yellowish-white flesh. Fruit are over-mature when more than half of the cross sectional area of the fruit is transparent Specific Gravity The specific gravity of the fruit was determined by measuring fruit weight in air(w1)and water(w2). The specific gravity of a ripe pineapple is found between 0.93-0.98  

6. CHEMICAL METHODS Total Soluble Solids (TSS) To measure the Total Soluble Solis (TSS), juice should be taken from he whole fruit. The TSS content should be atleast 12 °Brix ( 18-19 ° Brix for kew cultivar)

7. Titratable Acidity Titratable acidity (TA) can be determined by titrating a known volume of fruit juice with 0.1 N NaOH (sodium hydroxide) to an end point of pH = 8.2 as indicated by phenolphthalein indicator or by using a pH meter. The TA, is expressed as percentile citric acid and the value obtained for properly matured pineapple is 0.5 to 1.6% (0.77-0.83% forKew ) TSS:Acid Ratio The Acid :TSS blend brings better taste of pineapple and it is said to be the most reliable indication if maturity. During ripening the pineapple showing a TSS:Acid ratio of 23-25 are matured enough for harvest

8. Ascorbic Acid Content Ascorbic acid should fall between 20-65 mg/100grm of fresh weight depending on the cultivar and stage of maturity

9. PHYSIOLOGICAL METHODS Respiration Rate The respiration temperature for ripe pineapple is averaged to be 7-10 mg/kg/hr at room temperature .

10. Rates of Ethylene Production Less than 0.2 µl C 2 H 4 / kg·hr at 20°C (68°F) 

11. NON DESTRUCTIVE METHOD Acoustic Impulse Method this method applies free vibrations to the fruit and detect the characteristics of the fruit in the sound that is produced. A stiffness factor provided by he technique which was based on the resonant frequency and the mass of the intact fruit was found to relate to firmness of the fruit.

12. Near Infrared Spectroscopy The near infrared spectroscopy (NIR) give a accurate prediction on the soluble soilds content in pineapple.