Maturity Indices of Fruits
Maturity Indices
Introduction to Maturity of Fruits
Consumer Acceptance: Fruits must be acceptable to consumers.
Peak Edible Quality: Fruits should reach their peak edible quality for optimal taste and enjoyment.
Quality Preservation: Once harvested, the quality cannot be improved but can be preserved during storage.
Marketable Characteristics: Fruits should exhibit acceptable size, appearance, and flavor, suited for market.
Shelf Life: Storage capability varies depending on the type of fruit; adequate shelf life is crucial.
Types of Maturity Indices
There are two primary maturity indices used to assess fruit maturity:
Physiological Maturity Indices
Definition: The stage when the fruit is mature, ready for processing or consumption.
Commercial Maturity Indices
Definition: The stage when the fruit has reached certain characteristics preferred by consumers and buyers.
Methods for Determining Maturity
Visual Means
Aspects: Color, size, and shape of the fruit are indicators of maturity.
Color Assessment:
Common method for assessing ripeness.
Influenced by the experience and decision of harvesters.
Color charts are available for many fruits, e.g., apple, peach, and tomato.
Physical Means
Firmness Assessment:
Texture and firmness change rapidly as fruits mature; they generally soften upon ripening.
Touch assessments or the use of a fruit penetrometer can determine firmness.
Abscission Assessment:
Development of an abscission layer at the pedicel is a natural maturation process.
This layer facilitates easier harvesting manually or with machines.
Example: Harvesting cantaloupes before abscission formation results in poor taste and decreased shelf life.
Specific Gravity Assessment:
The specific gravity of fruits increases as they mature; those that float in water are less mature than those that sink.
Chemical Methods
Sugar Content:
Sugars play a crucial role in determining the ripening stage of a fruit.
They contribute to the Total Soluble Solids (TSS) content, which can be measured using a refractometer.
Starch Content:
Particularly useful for fruits like pears and apples.
During maturation, starch converts to sugars; a blue-black stain indicates the presence of starch.
Harvesting typically begins when 65-70\% of the cut surface develops this blue-black color.
Example: Gala apple exhibits specific storage duration:
Short-term storage: 5 – 6 weeks
Long-term storage: 3 – 4.5 months
Acidity Level:
The acidity level decreases as fruits mature; this is significant for both climacteric and non-climacteric fruits.
For climacteric fruits, accumulated starch converts to sugars.
For non-climacteric fruits, sugars accumulate as the fruit matures.
Titratable acidity can be measured to assess the maturity of fruits.
Computational Methods
Days from Full Bloom (DFFB):
The optimum days from full bloom can vary by fruit type and variety; for example:
Gala apple can be harvested at 130 DFFB.
Red Velox may be harvested at 150 DFFB.
Challenges in DFFB calculation arise when flowering occurs over a prolonged period.
Physiological Methods
Climacteric Fruits:
Fruits should be harvested at the full maturity stage.
Ripening continues post-harvest, and respiration rates increase with maturity.
These fruits tend to be harder and often do not require specialized packing.
Non-Climacteric Fruits:
Harvested at a fully ripened stage, with ripening cessation post-harvest.
These fruits have lower respiration rates at maturity and are typically softer, necessitating specialized packing for transport.
Other Methods
Optical Method:
As fruits ripen, chlorophyll content decreases.
The rate of fluorescence is measured, which helps estimate chlorophyll levels (degree of degreening), thus determining the ripening stage.