This presentation covers the concept of maturity and maturity indices in fruits and vegetables, essential for optimizing harvest timing and postharvest quality. It explains physiological and horticultural maturity, discusses the importance of proper harvest stage, and details various subjective and objective methods for assessing maturity. Understanding these indices ensures better storage, transport, and marketability of produce. Key academic terms include maturity, physiological maturity, maturity indices, harvest, and quality.
Introduction to Maturity and Maturity Indices
- Maturity is the stage when fruits or vegetables are fully developed and can ripen normally after harvest.
- Proper harvest timing is crucial for maintaining postharvest quality.
- Maturity indices are signs or measurements indicating readiness for harvest.
- Harvesting at correct maturity improves shelf life, flavor, and market value.
Concept of Maturity
- Maturation is the process leading to full tissue development in fruits and vegetables.
- Ripening occurs after maturity and involves flavor and color development.
- After maturity, the fruit relies on its own reserves as the supply from the plant stops.
- The stage of maturity at harvest affects storage life and quality.
Effects of Premature and Overmature Harvesting
- Premature harvesting leads to poor quality, low sugar, high acidity, and poor flavor.
- Immature fruits may not ripen properly and have short shelf life.
- Overmature fruits are prone to spoilage and have reduced storage life.
- Proper harvest stage is essential for optimal yield and marketability.
Principles of Harvest Maturity
- Produce should reach peak acceptable quality for consumers at the time of sale.
- Fruits and vegetables must have acceptable flavor, appearance, size, and shape.
- Harvested produce should be safe and non-toxic.
- Harvest maturity should ensure adequate shelf life and handling properties.
Types of Maturity
- Physiological maturity: Stage when fruit can ripen normally after harvest; applies mainly to fruits and fruit vegetables.
- Climacteric fruits: Harvest at mature but unripe stage for storage and transport.
- Non-climacteric fruits: Harvest at ripe stage for best quality.
- Horticultural (commercial) maturity: Stage when produce meets consumer and market preferences; varies by intended use and variety.
Classification of Horticultural Maturity
- Physiologically immature: Not ready for harvest, poor quality.
- Firm and mature: Optimal for harvest, good quality and handling.
- Harvest ripe: Fully ripe, best for immediate consumption but limited shelf life.
Advantages of Estimating Maturity
- Maintains product quality and freshness.
- Improves storage life and handling.
- Facilitates ripening and senescence management.
- Maximizes returns and enables long-distance transport.
- Helps manage pest and disease risks.
Maturity Indices: Definition and Importance
- Maturity indices are signs or measurements indicating readiness for harvest.
- Ensure sensory quality (flavor, color, aroma, texture, nutrition).
- Enable adequate postharvest life and market scheduling.
- Facilitate efficient harvest and packing operations.
Types of Maturity Indices
- Subjective indices: Qualitative; based on senses (color, size, shape, firmness, sound, juice content).
- Objective indices: Quantitative; measurable (TSS, acidity, starch, oil content, firmness, dry matter, days after bloom, heat units, respiration, ethylene).
Visual Indices/Methods
- Size, shape, and surface character indicate maturity (e.g., banana fingers become rounded, mango shoulders fill out).
- Surface gloss changes (melons, grapes) and drying of leaves or bracts (root crops) are indicators.
- Skin color changes from green to yellow/red/purple as fruits mature.
- Color charts and colorimeters provide objective color measurement.
Physical Methods
- Firmness/solidity assessed by hand pressure (lettuce, cabbage) or penetrometer (e.g., mango: 1.75–2 kg/cm²).
- Tenderometer measures pea maturity based on texture.
- Finger squeeze/touch used for peas, beans, okra (experience-based).
- Specific gravity increases with maturity; used for grading (e.g., Dasheri mango: 1.02).
- Juice content increases as fruit matures; measured by extracting and quantifying juice volume.
- Acoustic/sound tests (e.g., watermelon, jackfruit) detect maturity by tapping.
- Other methods: exudation of latex (papaya), electrical properties, NMR, X-rays (lettuce).
Chemical Measurements
- Total soluble solids (TSS) measured with a refractometer; indicates sugar content.
- Titratable acidity (TA) determined by titration; acidity decreases with maturity.
- Brix:acid ratio is a key indicator of flavor and maturity.
- Oil content used for avocados; minimum 8% oil (excluding skin and seed) for harvest.
- Starch content measured for crops like apples and bananas; decreases as fruit ripens.
Calculated Indices
- Calendar date: Based on typical harvest periods for varieties and locations.
- Days from full bloom (DFFB): Reliable but varies with season and location (e.g., mango: 110–125 days).
- Growing degree days (GDD): Cumulative heat units predict maturity; base temperature varies by crop.
- GDD formula: (Daily mean temp – Base temp) × Number of days (flowering to harvest).
Physiological Methods
- Respiration rate: Climacteric fruits show a rise at maturity (e.g., apple, pear).
- Internal ethylene evolution: Peaks at maturity in climacteric fruits.
- Volatile production: Specific aroma compounds indicate maturity (e.g., apple: ethyl-2-methyl butyrate).
Summary: Integrated Use of Maturity Indices
- Combining subjective and objective indices ensures accurate harvest timing.
- Selection of indices depends on crop, intended use, and market requirements.
- Proper maturity assessment maximizes quality, shelf life, and market value.
Objective Questions
Q1. What happens to the inflow of food material from the plant once a fruit reaches maturity?
A. It increases
B. It stops due to abscission layer
C. It decreases gradually
D. It becomes irregular
Answer: B
Q2. Which of the following is a consequence of premature harvesting of fruits?
A. Increased sugar content
B. Poor quality and faster deterioration
C. Enhanced flavor development
D. Longer storage life
Answer: B
Q3. For distant market and storage, when should climacteric fruits be harvested?
A. At full ripe stage
B. At immature stage
C. At maturity before ripening
D. At senescence
Answer: C
Q4. Which instrument is specifically used to test the maturity of peas by measuring tenderness?
A. Penetrometer
B. Tenderometer
C. Hydrometer
D. Colorimeter
Answer: B
Q5. Which maturity index is considered objective and quantitative?
A. Color
B. Size
C. TSS (Total Soluble Solids)
D. Aroma
Answer: C
Q6. What is the base temperature for calculating growing degree days (GDD) for spinach?
A. 10°C
B. 13°C
C. 15°C
D. 2°C
Answer: D
Q7. Which method is used to determine the maturity of lettuce in the industry?
A. Penetrometer
B. X-rays
C. Color chart
D. Tenderometer
Answer: B
Q8. Which of the following is NOT a principle of harvest maturity?
A. Produce should be toxic
B. Produce should develop acceptable flavor
C. Produce should have optimum size and shape
D. Harvested commodity should have peak quality at consumption
Answer: A
Q9. Which fruit's maturity can be assessed by the rounding of individual fingers from an angular shape?
A. Mango
B. Banana
C. Melon
D. Papaya
Answer: B
Q10. What is the minimum oil content required in avocados at the time of picking?
A. 5%
B. 6%
C. 7%
D. 8%
Answer: D