CRSCI 3200 LEC - MODULE 1

Introduction and Importance of Postharvest Handling Pre-harvest Factors Affecting Quality of Harvested Crops

Postproduction

• general term applied to the handling of crops from harvest

  up to the time they reach the consumer.

Postharvest handling

operations undertaken from the time of the crop is detached

from the parent plant up to the time the crop in fresh or

whole form reaches the end user (e.g. consumer, processor

manufacturer).

Postharvest technology

constitutes an inter-disciplinary science after harvest

Primary processing

removal of

unneeded part not intended to

be processed into other forms

Secondary processing

conversion of harvested crop into stable form

14%

Moisture content to be maintained for in Durable crops

75-95%

Moisture content to

be maintained in Perishable crops

Threshing
drying
fumigation
controlled
atmosphere storage
grading

Technologies

involved in durables

Trimming, cleaning,

curing, waxing, grading,

degreening, ethylene

treatment, precooling,

hot water treatment,

modified and

atmosphere packaging

Technologies

involved in perishables

Green life

from harvest up to the time a fruit losses its green color

Storage life

start to end of any method of commercial storage

shelf life

after harvest

Post storage life

time that commodity will last after storage regardless of storage

QUANTITATIVE LOSS

Decline in the availability, utility and saleable

weight

QUALITATIVE LOSS

Decline in acceptability by the consumer

COMMODITIES, PRODUCE, HARVEST

Commonly refers to the harvested crops

1 To maintain quality (appearance,

texture, flavor, nutritive value);

2 To protect food (safety), and

3 To reduce losses between harvest

and consumption.

Objectives of Postharvest Technology

Requires energy

Constant state of change

High in water content

Delicate or sensitive to adverse environmental conditions

Subject to attack by pathogens and insects

Characteristics of Perishable Crops

softening

collapsing tissue

protopectin to pectinic acid

color change

oxidation of chlorophyll

middle lamella

a thin layer primarily composed of pectin that acts as a cementing layer between the primary cell walls of adjacent plant cells

Bruising injuries

internal discoloration of damaged tissues

Chilling injury

happens when crops are exposed at low

but non-freezing temperatures. Such crops are mostly

of tropical or subtropical origin, but a few temperate

crops may be affected.

Freezing injury

when crops are kept at 0 to -2

°C producing water-soaked or glassy appearance.