Lec 5

Question 1

These are crops whose MC can be
brought down to a low level (14%),
thus the crops could last for a year.
Examples are: cereals and grains

Answer 1

Durables

Question 2

These are crops having very high
moisture content (MC) ranging from 75 - 90%, hence do not last for more than a
week
under ordinary conditions.
Examples are: fruits, vegetables, florist
crops, florist greens, young coconut, herbs, roots and bulb crops (slightly)

Answer 2

Perishables

Question 3

One of the oldest methods of preserving food.

Answer 3

Drying

Question 4

Purpose of Drying

Answer 4

-To preserve perishable raw food commodity against deterioration or spoilage
-To reduce the cost and difficulty of packaging, handling, transportation and storage

Question 5

Drying is a complex operation involving ___

Answer 5

Heat Transfer

Question 6

Physical changes that may occur

Answer 6

shrinkage
puffing
crystallization
glass transitions.

Question 7

desirable or undesirable chemical or biochemical reactions may occur

Answer 7

changes in color, texture, odor, or other properties of the solid product

Question 8

the energy that causes an object to change temperature

Answer 8

Sensible heat

Question 9

the energy added to an object in order for it to change state

Answer 9

Latent heat

Question 10

Foods can be dehydrated by various means:

Answer 10

sun
conventional oven
electric dehydrator
microwave oven
air drying
solar drying

Question 11

like other preservation methods this requires
energy

Answer 11

Dehydration

Question 12

A higher vapor pressure gradient means that moisture will move more rapidly from the interior of the product to the surrounding air. Similarly, a greater temperature gradient enhances the rate of moisture evaporation.

Answer 12

Faster Dehydration

Question 13

Maximizing the vapor pressure and temperature gradients allows for quicker moisture removal at lower energy costs. This efficiency is particularly important in industrial dehydration processes, where energy consumption can be a significant operational expense.

Answer 13

Energy Efficiency

Question 14

Rapid dehydration helps to preserve the quality of the product. For food items, this means retaining flavor, color, and nutritional value.

Answer 14

Quality Preservation

Question 15

Moisture content is often directly correlated with the growth of bacteria, mold, and other microorganisms. With the efficient removing moisture from the product, dehydration systems help to inhibit microbial growth, thus extending the shelf life and preventing spoilage.

Answer 15

Prevention of Spoilage

Question 16

Maximum gradients enable better control over the
dehydration process, ensuring consistent results batch after batch.

Answer 16

Consistency and Control

Question 17

Shorter drying times mean higher throughput and increased productivity, which can lead to cost savings and improved competitiveness in the market.

Answer 17

Reduced Drying Time

Question 18

mechanical grain dryer wherein the grain in fixed amount is held in the drying chamber in batches until the grain reaches the desired moisture content

Answer 18

batch type

Question 19

batch type dryer wherein a fixed amount of grain is held stationary in a horizontal grain holding bin

Answer 19

flat bed type

Question 20

batch type dryer equipped to circulate and/or mixed fixed amount of grain during the drying operation

Answer 20

recirculating type

Question 21

dryer in which the material being dried moves through the drying chamber in a substantially continuous stream and is discharged without being recirculated and where the drying and tempering processes are accomplished in another holding bin or column

Answer 21

continuous flow dryer

Question 22

device used to remove grain moisture by forcing heated air through the grain mass until the desired moisture content is attained

Answer 22

heated-air mechanical grain dryer

Question 23

dryer in which the products of combustion come into direct contact with the product being dried

Answer 23

dryer, direct-fired

Question 24

dryer in which the products of combustion do not come in contact with the products being dried

Answer 24

dryer, indirect-fired

Question 25

Types of Fuel Source

Answer 25

Renewable (BIGSHOW)
Non-Renewable

Question 26

This process is accomplished by exposing a relatively small piece of product to high pressure and high temperature for a short time, after which the product is moved to atmospheric pressure. This results in flash evaporation of water and allows vapors from the interior parts of the product to escape. Products produced by puff-drying have very high porosity with rapid rehydration characteristics. The puff-drying process is accomplished most efficiently by using 2-cm cube shapes.

Answer 26

Puff Drying