Post-Harvest Handling of Vegetables

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Questions and Answers

What is the primary purpose of blanching in food processing?

To add flavor to vegetables

To inactivate natural enzymes that cause discoloration and off-flavors and aromas (correct)

To remove harsh flavors from vegetables

To reduce the nutritional value of vegetables

What is the ideal temperature for blanching vegetables in hot water?

95°C (203°F)

80°C (176°F)

88°C (190°F) (correct)

100°C (212°F)

What is the result of removing water from vegetables during dehydration?

Reduced volume and weight (correct)

Increased moisture content

Reduced nutritional value

Increased volume and weight

What is the purpose of rapid cooling after blanching?

To retain better quality Signup and view all the answers

Which of the following is NOT a method of dehydrating vegetables?

Boiling Signup and view all the answers

What is a common practice for roots and legumes after harvesting?

Bulk handling and grading Signup and view all the answers

What is the effect of blanching on microorganisms in vegetables?

It reduces the number of microorganisms Signup and view all the answers

Why are treatments necessary for some vegetables?

To extend their shelf life Signup and view all the answers

What is the purpose of washing and waxing some vegetables?

To improve their shelf life and attractiveness Signup and view all the answers

What is the benefit of modified-atmosphere packaging?

It slows the respiration rate and senescence of cut vegetables Signup and view all the answers

What is the atmosphere composition in modified-atmosphere packaging?

High in carbon dioxide and low in oxygen Signup and view all the answers

What is the purpose of vacuum packing and modified-atmosphere packaging?

To increase the shelf life of vegetables Signup and view all the answers

What treatment helps to preserve the texture of potatoes during the reconstitution process?

Precooking and cooling Signup and view all the answers

What is the primary function of sulfite in dehydrating potatoes?

Aiding heat transfer and acting as a blanching agent Signup and view all the answers

Why is canning a suitable method for food preservation in developing countries?

It is particularly useful in areas where refrigeration is limited or nonexistent Signup and view all the answers

What happens to the containers during the canning process?

They are sealed while hot Signup and view all the answers

What is the main purpose of the heat treatment during canning?

To ensure the destruction of bacteria spores Signup and view all the answers

Why is the industry searching for sulfite replacements?

Due to consumer concerns about allergies Signup and view all the answers

What is a limitation of freeze-drying in vegetable products?

It is too expensive Signup and view all the answers

What is a characteristic of dehydrated potato granules?

They have a pasty texture Signup and view all the answers

What is the purpose of air-lift drying in dehydrated potato granules production?

To bring the product to 10–13 percent moisture Signup and view all the answers

What is the difference between dehydrated potato flakes and granules?

Flakes have a mealy texture, while granules have a pasty texture Signup and view all the answers

What is used to dry dehydrated potato flakes to final moisture content?

Steam-heated drum drier Signup and view all the answers

What is the texture of mashed potatoes made from dehydrated potato flakes?

Mealy Signup and view all the answers

What is a possible cause of bulged cans after long periods of storage?

Inadequate heat processing Signup and view all the answers

What is the nutrient most susceptible to destruction in canning?

Vitamin C Signup and view all the answers

What is the process of aseptic canning also known as?

High-temperature–short-time (HTST) processing Signup and view all the answers

What is a characteristic of frozen foods?

Outstanding quality and high nutritive value Signup and view all the answers

What is a possible consequence of consuming canned vegetables with bulged cans?

Botulism Signup and view all the answers

Why may some canned vegetables have inferior quality and less nutritive value?

Severe heat treatment Signup and view all the answers

Study Notes

Dehydration

Freeze-drying produces high-quality food, but it is costly and rarely used for vegetables
Dehydration is an old method of preserving food, removing water to reduce volume and weight, and aiding storage and transportation

Potato Products

Instant potatoes are a common dehydrated product, used in restaurants and institutions
Dehydrated potato granules have high bulk density, easy to handle, but produce mashed potatoes with a pasty texture
Dehydrated flakes, on the other hand, produce mashed potatoes with a mealy texture, comparable to freshly prepared mashed potatoes
Air-lift drying is used for granules, while steam-heated drum drying is used for flakes

Processing Vegetables

Harvesting roots and legumes often involves machine-based harvesting, with some sorting and grading in the field or at collection stations
Bulking is common, with few additional preparation steps before distribution
Treatments may be necessary to prevent microbial spoilage, insects, and small animal invasion
Washing, sorting, grading, cutting, and packaging into retail-size containers are steps taken for convenient foods

Blanching

Blanching involves heating vegetables in hot water or steam to inactivate natural enzymes, reduce microorganisms, and make them limp for easy packing
Blanching also serves to remove harsh flavors in some vegetables

Dehydration Methods

Many machines are available for dehydration, including tunnel drying, vacuum drying, drum drying, spray drying, and freeze drying

Canning

Canning is a major food-processing method, particularly useful in developing countries where refrigeration is limited
Properly processed canned vegetables can be stored at room temperature for years
Aseptic canning, or high-temperature–short-time (HTST) processing, is a superior method that avoids slow heat penetration and produces high-quality products

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Description

Learn about the different steps involved in handling and preparing vegetables for distribution, including sorting, grading, and treatments to prevent spoilage. This quiz covers the process of handling roots, legumes, and other vegetables that require long-term storage.