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Questions and Answers

What is the main purpose of postharvest handling?

  • To reduce the moisture content of crops
  • To enhance the flavor of the fruits
  • To prevent losses of produce due to deterioration (correct)
  • To increase the quantity of crops harvested

Which of the following best describes climacteric fruits?

  • Fruits that have high moisture content and can ripen after picking (correct)
  • Fruits that require refrigeration for storage
  • Fruits that have low humidity requirements
  • Fruits that cannot ripen after removal from the plant

What does the term 'postharvest life' refer to?

  • The time taken to transport crops to market
  • Duration of usability of a commodity (correct)
  • The storage time of perishables
  • The time crops are harvested before being sold

Which characteristic is true for durable food crops?

<p>They can be stored for a longer duration (B)</p> Signup and view all the answers

What environmental condition is referred to by 'ambient'?

<p>Ordinary room temperature and humidity (B)</p> Signup and view all the answers

Why should crops be harvested during the cooler parts of the day?

<p>To prevent wilting and deterioration (D)</p> Signup and view all the answers

Which statement accurately differentiates between perishables and durables?

<p>Perishables are usually high in moisture and have a shorter shelf life than durables. (A)</p> Signup and view all the answers

What is a key factor that affects the quality of harvested produce?

<p>The handling of produce postharvest (D)</p> Signup and view all the answers

What is the main goal of primary processing in postharvest handling?

<p>To prepare products for consumer markets (B)</p> Signup and view all the answers

Which of the following is NOT a consequence of inadequate refrigeration during postharvest storage?

<p>Increase in marketable weight of produce (B)</p> Signup and view all the answers

How does storage temperature affect the respiration rate of produce?

<p>Higher temperatures increase respiration rates (D)</p> Signup and view all the answers

What is considered the single most important factor in maintaining the quality of perishable crops postharvest?

<p>Temperature control (C)</p> Signup and view all the answers

Which process is NOT typically promoted through effective post-harvest storage technologies?

<p>Enhancing ethylene production (B)</p> Signup and view all the answers

What effect does respiration have on postharvest produce quality?

<p>It contributes to the loss of stored food reserves (A)</p> Signup and view all the answers

Which of the following is a key post-harvest life process that affects the quality of fruits and vegetables?

<p>Respiration (A)</p> Signup and view all the answers

What potential issue arises due to mechanical damage during the postharvest chain?

<p>Compromised natural barriers (B)</p> Signup and view all the answers

What is the primary purpose of sanitation during postharvest storage of vegetables?

<p>To avoid infections by pathogens (A)</p> Signup and view all the answers

Which of the following best describes Modified Atmosphere (MA) storage?

<p>Designed to maintain 2% - 5% of O2 and 8% - 12% of CO2 (A)</p> Signup and view all the answers

What type of atmosphere is primarily used for the storage and transport of apples and pears?

<p>Controlled atmosphere (CA) (C)</p> Signup and view all the answers

For which of the following commodities is controlled atmosphere storage typically least used?

<p>Kiwifruits (D)</p> Signup and view all the answers

What happens to the respiration rate of produce as temperature increases above optimum levels?

<p>It increases 2 to 3 fold for every 10ºC rise. (C)</p> Signup and view all the answers

What storage duration range is associated with fresh fruits such as bananas and avocados?

<p>1-3 months (B)</p> Signup and view all the answers

Which internal factor does NOT affect respiration rates?

<p>Temperature. (A)</p> Signup and view all the answers

How does relative humidity affect transpiration rates?

<p>Higher humidity decreases transpiration. (A)</p> Signup and view all the answers

What is the typical relative humidity range recommended for storing fruits?

<p>85-95% (D)</p> Signup and view all the answers

What characteristic differentiates climacteric fruits from non-climacteric fruits regarding ethylene production?

<p>Climacteric fruits produce larger quantities of ethylene. (D)</p> Signup and view all the answers

What is the primary goal of pre-cooling harvested crops?

<p>To remove field heat quickly before storage. (D)</p> Signup and view all the answers

Which factor increases the transpiration rate of produce?

<p>Higher temperature. (A)</p> Signup and view all the answers

Which method can help reduce transpiration rates of stored products?

<p>Using physical barriers. (D)</p> Signup and view all the answers

Which vegetable species requires rapid pre-cooling due to its high respiration rate?

<p>Broccoli (C)</p> Signup and view all the answers

What is one disadvantage of room cooling compared to other pre-cooling methods?

<p>It is slower than other cooling methods. (D)</p> Signup and view all the answers

Which pre-cooling method is recommended to reduce heat and can also clean produce simultaneously?

<p>Hydro cooling (C)</p> Signup and view all the answers

Which pre-cooling method is particularly effective for dense products that are difficult to cool with forced air?

<p>Top or liquid icing (D)</p> Signup and view all the answers

What is the primary role of fans in forced-air cooling?

<p>To pull cool air through packages of produce. (D)</p> Signup and view all the answers

Why is a disinfectant recommended in hydro cooling methods?

<p>To reduce the spread of diseases. (A)</p> Signup and view all the answers

Which of the following vegetables should not be hydro cooled due to its susceptibility to wetting?

<p>Garlic (C)</p> Signup and view all the answers

What is the main advantage of forced-air cooling over room cooling?

<p>It cools produce 75-90% faster. (D)</p> Signup and view all the answers

Which pre-cooling method is best suited for leafy crops?

<p>Vacuum cooling (C)</p> Signup and view all the answers

What is a primary drawback of vacuum cooling?

<p>The cost of the vacuum chamber system (C)</p> Signup and view all the answers

At what range of temperatures do many vegetables and fruits store best?

<p>13 to 17°C (A)</p> Signup and view all the answers

What can indicate chilling injury in produce after a few days at warmer temperatures?

<p>Pitting or skin blemishes (D)</p> Signup and view all the answers

What relative humidity range is generally preferred for storing produce to retain quality?

<p>80 to 95% (B)</p> Signup and view all the answers

What is a consequence of excessive water loss in produce?

<p>Wilt appearance and weight loss (D)</p> Signup and view all the answers

What complicates the maintenance of high relative humidity in storage rooms?

<p>The removal of moisture by refrigeration (D)</p> Signup and view all the answers

Which methods are essential alongside cool temperatures in storage rooms to prevent disease growth?

<p>Proper sanitation and preventive methods (D)</p> Signup and view all the answers

Flashcards

Postharvest handling

The movement and operations of a commodity from harvest to the consumer.

Perishables (food)

Food crops that stay good for a short time after harvest.

Durables (food)

Food crops that stay good for a long time after harvest.

Respiration (in plants)

The process where plants break down food to release energy and heat.

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Climacteric fruits

Fruits that ripen after being picked, producing more ethylene.

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Non-climacteric fruits

Fruits that cannot ripen after being picked.

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Harvesting principle (temp)

Harvesting should be done during cool times of the day (early morning).

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Harvesting principle (handling)

Handle produce gently to avoid damage.

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Primary Processing

Postharvest handling to prepare produce for consumers or further processing.

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Secondary Processing

Postharvest handling to create a final product, often in food or industrial settings for non-food crops.

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Post-Harvest Storage

Maintaining produce quality to make it acceptable for consumers through proper storage techniques.

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Temperature Impact (Storage)

Temperature is crucial for maintaining produce quality; it slows spoilage and prevents ripening/softening.

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Respiration Rate

How quickly plant cells use stored food, impacting quality and shelf life.

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Mechanical Damage (Post-Harvest)

Physical harm to produce after harvest, increasing spoilage risk and affecting quality.

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Transpiration

Loss of moisture from fruits and vegetables, leading to wilting and quality loss.

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Ethylene Production

A gas produced by produce impacting ripening and decay speeds; affecting storage and transportation.

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Respiration Rate & Temp

Respiration rate increases significantly with every 10°C rise in temperature above the optimum.

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Ethylene's Role

Ethylene gas accelerates respiration and ripening in fruits, especially climacteric ones.

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Humidity & Transpiration

High relative humidity slows down transpiration, while low humidity increases it.

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Temperature & Transpiration

Higher temperatures increase transpiration rate because water evaporates faster.

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Pre-Cooling

Rapidly removing field heat from harvested produce to extend shelf life.

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Pre-cooling Importance

Rapid pre-cooling is crucial for vegetables with high respiration rates, as they produce heat and deteriorate quickly.

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Low Respiration Vegetables

Vegetables like garlic, onions, potatoes, and sweet potatoes have low respiration rates, meaning they don't produce as much heat and stay fresh longer.

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Room Cooling

A simple method where produce is placed in a refrigerated room. It's suitable for most commodities, but slower compared to other methods.

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Forced-Air Cooling

Fans circulate cool air through produce packages, significantly faster than room cooling. Temperature is controlled with a thermostat.

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Hydro Cooling

Produce is submerged in cold water or sprayed with it, effectively removing heat and cleaning. Not suitable for all vegetables.

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Top Icing

Crushed ice is added on top of produce in containers, best for dense products and palletized packages.

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Liquid Icing

A mix of water and ice is injected into produce packages, ideal for palletized products without removing them.

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Why Pre-cool?

Pre-cooling helps maintain quality and extends shelf life by slowing down respiration and preventing spoilage.

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Vacuum cooling

A pre-cooling method where produce is placed in a sealed chamber, and a vacuum is created. This causes water inside the produce to evaporate, removing heat and cooling it.

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Ideal for vacuum cooling

Leafy crops, such as lettuce, are best suited for vacuum cooling due to their high surface-to-volume ratio, allowing faster heat removal.

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Chilling injury

Damage to produce caused by prolonged exposure to low temperatures, even above freezing. It can cause discoloration, blemishes, and failure to ripen.

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Chilling injury symptoms

Symptoms of chilling injury may not be immediately visible but appear after a few days of warmer temperatures, including pitting, discoloration, and failure to ripen.

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Relative humidity importance

High relative humidity (RH) in storage is crucial for preventing excessive water loss in produce, preserving its quality and preventing wilting.

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High RH drawback

While high RH is good for quality, it can also encourage disease growth in storage.

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RH maintenance challenge

Refrigeration systems can remove moisture, making it harder to maintain high RH in storage rooms.

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Humidifier solution

Humidification devices, such as spinning disc aspirators, are used to increase the RH in storage rooms, combating moisture loss from refrigeration.

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Ethylene

A plant hormone that speeds up ripening in fruits and vegetables, shortening their shelf life.

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Modified Atmosphere (MA)

A method of storing fruits and vegetables by lowering oxygen levels and increasing carbon dioxide to slow down ripening and spoilage.

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Controlled Atmosphere (CA)

A more precise method of storing fruits and vegetables where oxygen and carbon dioxide levels are carefully regulated to prolong shelf life.

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What are storage duration ranges for avocados?

Avocados can be stored for 1 to 3 months in controlled conditions.

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What storage duration range is for apples?

Some apple cultivars can be stored for 6-12 months under controlled conditions.

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Study Notes

Harvest and Postharvest Technology

  • A cyclical process encompassing pre-planting, planting, growth, weed management, water management, soil fertility, and pest/disease control. Postproduction encompasses harvesting, milling/processing, storage, and drying.
  • Seed quality, rice varieties, and crop calendars are pre-planting elements that influence the overall process.
  • Quality is maintained through appropriate production practices, careful harvesting, proper packaging, storage and transport.

Terms

  • Postproduction: The handling of products from harvest until they reach the final consumer.
  • Postharvest handling: The movement and operations of commodities from harvest to consumer possession.
  • Postharvest life: The usability duration of a commodity.
  • Perishables: Food crops with short shelf lives after harvest.
  • Durables: Food crops that can be kept as food over a long time period.
  • Loss: A decrease in the quantity or quality of crops/products that reduces human consumption.

Terms

  • Respiration: A biological process where organic materials break down to release energy, accompanied by heat.
  • Relative Humidity: The ratio of water vapor pressure in the air to the saturation vapor pressure at the same temperature.
  • Ambient: Ordinary room conditions of temperature and relative humidity.
  • Climacteric Fruits: Fruits that ripen after being picked, producing more ethylene than non-climacteric fruits (e.g., apple, banana, mango, papaya).
  • Non-climacteric Fruits: Fruits that cannot ripen after being picked (e.g., citrus fruits, berries).

Comparison of Perishables and Durables

  • Perishables (Root Crops): High moisture content (75-95%), large unit sizes (5g-5kg), high to very high respiration rates, soft texture, prone to bruising, and have a shorter shelf life (days to months).
  • Durables (Cereals, Oilseeds): Low moisture content (10-20%), small unit sizes (<1g), very low respiration rates, hard textures, and longer shelf lives (years).
  • Losses in less developed countries (LDC) are typically higher (15-50%) for perishables compared to durables (10-20%).

Harvesting

  • Harvesting is the process of cutting or collecting crops from the field, which can be done manually or mechanically.
  • Ideal harvesting occurs at the right stage of physiological maturity. Delaying past this stage reduces quality and shelf life in the market.

Maintaining Quality of Produce after Harvesting

  • Appropriate harvesting, packaging, storage, and transport practices maintain produce quality.
  • Quality cannot be improved after harvest; it can only be maintained.
  • Fruits, vegetables, and flowers should be harvested at peak quality, avoiding immature or overripe produce for longer storage.

Maturity Indices for Annual and Field Crops

  • Maturity is crucial for quality, ripening, storage, marketing and consumption. Maturity is determined by the growth duration (days from germination to maturity), color changes (grains, pods, and fruits), appearance of foliage and physical condition (size).

Perishability Rate

  • A table illustrating a variety of produce and their time to perish.

Harvesting - Examples

  • Images depicting different methods and equipment for harvesting potatoes, lettuce, kohlrabi ,and green house tomatoes.

Mechanical Harvesting of Root Vegetables

  • Diagrams and information describing the process of mechanically harvesting root vegetables, including steps, tools, and types of machinery.

Other Harvesting Practices

  • Images illustrating methods for harvesting asparagus, leeks, celery and field cucumbers.

Principles of Harvesting

  • Harvest produce during the coolest part of the day.
  • Handle produce gently to avoid damage that can lead to spoilage.
  • Store produce free from bruises, spots, rots, decay, etc. Damage promotes microbial growth.

Packaging of Vegetables after Harvesting

  • Packaging techniques, and best practices in the handling and design to prevent damage. The images include packaging produce in situ and in packing houses, for storage or transportation.

Packing Line

  • A diagram displaying different steps in a produce packing line, highlighting receiving, inspection, initial cooling, sorting, labeling, drying, waxing, palletizing, cooling and storage.

Grading of Vegetable Products

  • Processes for grading produce in weight, size mechanically and electronically.

Packaging materials & methods

  • Various packaging materials and methods are illustrated to maintain quality, safety, and convenience.

Micropackaging

  • Photos of various micropackages used for fruits and vegetables including tomatoes, onions and lettuce.

Fresh-Cut Salads

  • Images and packaging information for pre-made fresh-cut salads.

Postharvest Handling

  • Crucial to reduce losses, maintain quality, and allow for appropriate product handling for consumers and further processing.
  • Processes are categorized as primary or secondary processing based on whether the handling prepares the product for market or for food/non-food industry.

Postharvest Storage

  • Storing produce in order to maintain quality for as long as possible, considering factors like temperature and humidity.

Impact of Temperature on Post-Harvest Life

  • Temperature is critical for maintaining quality.
  • Refrigeration slows ripening, softening, textural and color changes, and metabolic activity.

Fruits and Vegetables as Perishable Products

  • Key processes during post-harvest life include respiration, transpiration, ethylene production and maturity.

Impact of Storage Temperature on Respiration Rate

  • Higher storage temperature corresponds with a higher respiration rate leading to decreased quality and saleable weight, faster deterioration, and shorter product life.

Mechanical Damage during Postharvest Chain

  • Temperature influences mechanical damage severity, whilst compromising natural barriers also increases water loss and risk of pathogenic infection.

Impact of Storage Temperature on Shelf-Life of Vegetables

  • Plot showing the effect of storage temperature on vegetable shelf-life for commodities not susceptible to chilling injury.

Temperature Effects on Respiration Rate

  • High temperatures increase respiration and transpiration, reducing shelf life, whilst lower temperatures slow these processes.

Factors Affecting the Respiration Rates

  • External factors such as mechanical damage, temperature, atmosphere composition and internal factors like types of tissue and sanitary product conditions impact respiration.

Transpiration

  • Water loss from produce exposed to air through cuticle, lenticels and stomates.
  • External factors like relative humidity, temperature and wind.

Ethylene Production

  • Climacteric fruits produce high levels of ethylene, accelerating ripening and shortening shelf life.
  • Non climacteric fruits produce less ethylene, and thus ripen slower.

Relative Humidity Ranges

  • Different produce has optimum relative humidity ranges; for example, fruits have a range of 85-95% RH, while dry products (onions and pumpkins) are 70-75%, and root vegetables (carrots and radishes) need 95-100%.

Pre-Cooling

  • This is a critical initial processing step in maintaining quality and extends shelf life.
  • Most refrigerated storage rooms lack the cooling capacity and air movement to cool rapidly.
  • Pre-cooling equipment is needed.

Importance of Pre-Cooling for Different Vegetable Species

  • The need for pre-cooling is correlated to products with high respiration rates including artichokes and strawberries. Products with lower respiration rates like sweet potatoes may not require such urgent cooling.

Most Common Methods of Pre-Cooling

  • Methods for pre-cooling include room cooling, forced-air cooling, hydro-cooling, liquid icing, and vacuum cooling. These differ in the method of removing heat and maintaining product quality.

Chilling Injury

  • Vegetables and fruits best stored slightly above freezing temperatures; however, some vegetables can endure slightly lower temperatures for longer periods, before developing chilling injury signs.
  • Signs like pitting, discoloration or failure to ripen are common occurrences in some species.

Preventing Moisture Loss

  • High relative humidity in storage is complicated by refrigeration's water removal.
  • Methods like humidification are sometimes required to manage loss moisture, moisture loss impacts quality, leading to wilting and a loss of saleable weight.

Adjustment of Relative Humidity in Storage Rooms of Vegetables

  • Cooling helps reduce disease growth.
  • Maintaining high relative humidity in storage is difficult, as refrigeration removes water.
  • Humidification aids in maintaining the optimum level of humidity in the storage environment.
  • Techniques including sanitation, controlling ethylene, modified atmosphere (MA), and controlled atmosphere (CA). To reduce microbial growth, minimize ethylene production, regulate the gaseous atmosphere.

Modified Atmospheres

  • MA is used to extend shelf life of fresh-cut fruits and vegetables, especially in transportation.

Commercial Use

  • CA is utilized for transportation and storage in apples, pears, kiwi fruits, nuts, and dry fruits.
  • MA is utilized to extend shelf life of mangoes, bananas, peaches and other similar crops when transported.

Manipulation of the Environment around the Produce

  • Classification of horticultural crops according to their controlled atmosphere storage.
  • Storage duration and commodities are categorized into different ranges reflecting storage potential.

Ripening Process

  • Process involving cellular level degradation, with the aim of delaying tissue disintegration, and extending shelf life.
  • Key elements such as chlorophyll, aroma, and organelle breakdown can be delayed.

Fruit Ripening

  • Processes involved in fruit ripening include loss of chlorophyll, conversion of starches to sugars, fat and protein changes and reduction in tannins.

Retail Banana Ripening Guide

  • A guide showing the different stages of banana ripening from all green to yellow and finally brown.
  • Descriptions of each stage aid in determining the point of optimal harvest.

Maturity Indices of Different Mango Varieties

  • Data tables displaying stages, colour, and flesh firmness of different mango types.

Post-harvest Procedures

  • Flowchart illustrating post-harvest procedures.
  • Other factors such as curing (drying), trimming (removing), dehanding (removal of stalks, hands), dethorning (removing thorns), grading (criteria of quality), and packaging (technology) are outlined.

Post-harvest Practices for Horticultural Crops

  • A table listing different crops and their primary and secondary post-harvest practices.

Hazards Associated with Produce Quality

  • Categorization of produce hazards including biological hazards such as pests and diseases; chemical hazards such as chemical contamination with pesticide and chemical product; mechanical hazards such as injuries, cuts, bruises, and physical hazards such as heating, freezing, and water loss; physiological hazards such as sprouting, rooting, senescence.

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