Chapter 7: Processing and Preservation of Vegetables

After studying this chapter, you will be able to:

(a) sort the vegetables /herbs/spices for drying.

(b) explain the reasons for preserving vegetables.

(c) blanch vegetables (where applicable) in preparation for drying.

(d) explain how vegetables are affected by processing.

(e) dry vegetables/herbs/spices using a solar drier or a low temperature oven.

(f) pound/crush/grind dried vegetables/ herbs/spices into powder.

(g) package, label and sell the processed vegetables.

(h) follow recipes to prepare pickles, € chutney and sauces.

Keywords

• Blanching
• Chutney
• Enzymatic
• Food poisoning
• Herbs
• Microbial
• Pickles •
• Sauces •
• Solar drying
• Spices
• Spoilage
• Value addition

Introduction

Did you know that vegetables are one of the most perishable food items when fresh? They should be eaten as soon as possible after harvesting. By this time, their appearance is good and food content is high. However, you can extend vegetable shelf-life by processing and preserving them. You are able to preserve vegetables using a number of processing methods. These depend on the type of vegetables you are dealing with. Due to limited processing skills, most vegetables are consumed immediately they are harvested.

In this chapter, you will develop skills of processing and adding value to vegetables. This will be an effort to ensure food security, increasing vegetable supply and use as well as creating income generating projects. You will do this by drying the vegetables or by preserving them using chemicals and packaging and selling some of the products.

7.1: Classification of vegetables

Activity 7.1 Identifying vegetables in our local community

1. In small groups, identify and make a list of vegetables you eat at home/ school.

2. Find out the parts of vegetables that are eaten and classify them.

3. You can even look at a number of them in a school garden if you have.

7.2: Reasons for preserving vegetables

Preserving vegetables results into the following:

1. Extending the life of the vegetable product.

2. Reducing costs when out of season.

3. Raising awareness of different types of vegetable products.

4. Increasing variety in the diet.

5. Increasing the value of the vegetables.

Note:

(i) You should also make an effort as a learner of this subject to plant some vegetables at home or even at school.

(ii) Vegetables are subject to a natural cycle of growth; maturity and decay.

(iii) To prevent them from decay after maturity, a number of processes have to be done.

Activity 7.2 Researching about the need to preserve vegetables

1. Visit the nearby market/vegetable farmer and find what happens when the vegetables are mature and are not sold.

2. Take note of what happens to the vegetables. This can be observed by looking at those vegetables which have taken more than one day to a week, observe the garbage/dustbins.

3. Write down the different ways farmers could use to increase the shelf-life of their unsold vegetables.

7.3: Different ways of preserving vegetables

You could be interested in saving the vegetable seller/farmers from the loss due to spoilage of the vegetables. Can you think of several ways of processing vegetables? Share with other learners if you have seen people preserving vegetables.

How do they do it? What could happen to the vegetables during the processing? Some methods of processing vegetables may involve the following; drying and grinding, canning/ bottling and freezing among others. You can classify vegetables according to the part that is usually eaten. Many vegetables can be grown in the home for various purposes. You are free to eat them in a variety of ways as part of the main meal or a snack.

Drying of vegetables

Vegetable drying requires care and attention in order to save the food value in them. Drying is one of the simplest and most common methods of preserving fresh vegetables. Drying is the removal of moisture or water from harvested vegetables. Dried vegetables are frequently used in soups and stews. Have you ever dried vegetables at home? What happens to vegetables when you dry them?

Sorting vegetables

1. Sort the vegetables for drying. Good parts from bad ones in order for them to dry properly. Good quality vegetables dry well and quickly because they can easily be displayed when drying.

2. Spread the sorted vegetables to dry.

Blanching Vegetables

Blanching is putting sorted vegetables into hot salty water or steam Allow blanching for about 5 minutes and drain for 2 or 3 minutes. Some vegetables are blanched before drying to prevent colour changes and to reduce the number of contaminating micro-organisms, because the temperature of drying is not high enough to kill them. In hot water blanching, vegetables are immersed in boiling water in a wire basket

Figure 7.1: Blanching vegetables

Activity 7.3 Researching on the importance of blanching and drying vegetables

1. In small groups, use the internet to find out the importance of blanching vegetables before drying them.

2. What are the different ways you can use when drying vegetables?

3. Present your findings to the class.

Drying vegetables in an oven

Requirements

You will need a cooker, oven, and oven tray, paper for covering the tray, a knife, and the vegetables. The best temperature for drying vegetables is 60°C/140°F. If higher temperatures are used, the vegetables may “case harden”, that is cook and harden on the outside while trapping moisture on the inside.

Procedure

1. Set the oven to 60°C or its lowest setting.

2. Blanch the raw vegetables.

3. Slice vegetables into bite-size pieces.

4. Cover the baking tray with paper.

5. Place the sliced vegetables on the tray.

6. Place vegetables in the warm oven until they are dry.

7. Occasionally check on the vegetables in the oven.

Drying using a solar dryer

A solar dryer is a device that uses solar energy to dry substances, especially food.

Making a simple solar dryer

Requirements

You may need timber, greenhouse polythene sheet, nails, black web mesh and transparent polythene.

Activity 7.4 Making a simple solar dryer In groups follow the procedure given below and make a simple solar dryer.

1. Construct a heat absorbent shelf (approximately 23″ x 20″). This rests on the top of the legs.

2. Construct drying screen by stretching and stapling the polythene paper over a 14″ x 22 1/2″ frame constructed of 2″ x 2″ pieces.

3. Cut and attach support piece for drying screen.

4. Construct the drying screen rack using a black mesh for placing the food.

5. Attach the window with a shutter to allow air out.

6. Construct vents with screen material to protect from insects.

7. Clean the different parts before assembling them together.

Procedure for using a solar dryer

• Blanch the raw vegetables.
• Slice vegetables into bite-sized pieces.
• Cover the baking tray with paper.
• Place the sliced vegetables on the tray.
• Place vegetables in the warm drier until they are dry.
• Occasionally check on the vegetables in the dryer.

Activity 7.5 Drying vegetables

1. Follow the procedure you have learnt and dry a vegetable of your choice.

2. In small groups, discuss the different uses of dried vegetables. Processing dried vegetables into powder

Figure 7.3: Dried vegetable grinders

Different vegetables can be processed, for example tomatoes, carrots and any other vegetables in any way. They can be processed, cooked or eaten raw, peeled or unpeeled, or even sliced or unsliced. They can also be pureed, dried or ground into powder

Guidelines for grinding vegetables into powder

1. Dry the vegetable to be processed well to remove moisture. You can check this by dropping it onto a table. If it makes a clinking sound, you will know that you have removed most of the moisture.

2. Some vegetables will be ground into a powder easily with mortar and pestle, but a food processor will be required for most vegetables and especially for larger quantities.

3. Store the powdered vegetable in tightly sealed bags if you are to store for a long time. Keep in a dry dark place.

4. If it is to be used immediately, place the powder in a jar. The jar should be closed tightly to remove oxygen. Keep it away from heat, steam and light.

Activity 7.6 Packaging and labelling processed vegetables

1. Visit a shopping centre and find out different packaging materials.

2. Bring some of those samples from home and use them for packaging your dried vegetables.

3. Demonstrate to your classmates how packaging and labelling vegetables can be done. eds 2Seeds

Figure 7.4: Packaging and labelling processed vegetables

The label should contain the following information

(i) Name and address of the producer.

(ii) Name of the product.

(iii) List of ingredients (in descending order of weight).

(iv) Net weight of product in the package.

(V) A ‘use-by’ or ‘sell-by’ date.

In addition, a processor may include: instructions for preparing the product, storage information or instructions on storage after opening, examples of recipes in which the product can be used, and a bar code.

Dried vegetables last for a very long time. This makes them an excellent alternative food to have in your store. Here are some tips for making sure you get the best from your dried vegetables.

How you can use the dried vegetables

1. To every 1 cup of dried vegetable, add 2 cups of boiling/hot water.

2. To rehydrate and cook leafy or tender vegetables (spinach, kale, cabbage, chard, tomatoes), cover with hot water and simmer to desired tenderness.

3. Soak root, stem and seed vegetables (carrots, green beans, peas, corn) before cooking.

7.4: Preserving vegetables using chemicals

Traditionally, foods were preserved using chemicals like salt, sugar, alcohol and vinegar. These work by creating unfavourable environment for the micro-organisms or by drawing water out of the micro-organisms. Vinegar is used in pickles and chutney, and in processes which use heat treatment and sealing in sterile airtight jars. It is suitable for onions, beetroot, carrots, bitter tomatoes, okra and eggplants.

Figure 7.5: Preserving vegetables using chemicals

Can you think of other vegetables which can be preserved using use chemicals to make pickles, chutneys, sauces and marmalade.

Pickle making

Pickles are foods preserved in a solution, of either vinegar, brine (salt solution) or alcohol that encourages the growth of certain bacteria that are not harmful and also prevent the bacteria that will spoil the food. Vinegar is used in pickling solutions because its acidity varies between 5-10%. When foods are soaked in this acidic solution the very low pH prevents growth of organisms in the foods. The vinegar is usually flavored and enters into the food changing the texture and flavor.

Making a vegetable pickle

Ingredients

1. 500gms of vegetables(onions, carrots, bitter tomatoes, okra and eggplants beetroots)
2. 1 litre of vinegar
3. Brine solution: (100g salt to 500ml water)
4. 25g spices

Method

1. Wash and peel vegetables to remove any tough parts.
2. Chop if necessary.
3. Soak in brine solution for 24 hours.
4. Rinse, drain and pack into jars, leaving a 1 cm space at the top.
5. Heat the vinegar and spice for 5 minutes and leave to cool.
6. Pour the cooled vinegar mixture into the jars and cover securely.
7. Label and store.

Developing and writing a recipe for making a vegetable pickle

1. Follow the given procedures and make a vegetable pickle.

2. Discuss the different uses of pickles.

Example:

Pickled beetroot

Ingredients

1. 500g of beetroot
2. 1 litre of vinegar
3. Brine solution: (100g salt to 500ml water)
4. 25gms of spices

Method

1. Cook the beetroots till tender.
2. Rinse, drain and pack into jars, leaving a 1 cm space at the top.
3. Heat the vinegar and spice for 5 minutes and leave to cool.
4. Pour the cooled vinegar mixture into the jars and cover securely.
5. Label and store.

Pickled cauliflower

Ingredients

500gms of cauliflower 1tablespoon of turmeric 1 tablespoon of cumin seeds 1 tablespoon of coriander seeds 1 tablespoon of black mustard 1 shredded onion 1 litre of vinegar 100gms of sugar Brine solution: (100g salt to 500ml water)

Method

1. Clean the cauliflower and chop into small pieces. Add the onions.
2. Soak in brine solution for 24 hours.
3. Add the turmeric, coriander seeds, cumin seeds black mustard and salt.
4. Rinse, drain and pack into jars, leaving a 1 cm space at the top.
5. Heat the vinegar and spice for 5 minutes and leave to cool.
6. Pour the cooled vinegar mixture into the jars and cover securely.
7. Label and store.

Savory pickled peppers

Use white vinegar, water, sugar, olive oil, diced onion, diced carrots, peppers, mixed spice, bay leaves.

Ingredients

1. 500gms medium cucumbers
2. 1 1⁄2 cups sliced onions
3. 2 large garlic cloves, left whole
4. 1/3 cup of canning salt
5. 2 trays of ice cubes or crushed ice
6. 4 21⁄2 cups of sugar
7. 1 1⁄2 teaspoons of turmeric
8. 1 1⁄2 teaspoons celery seed
9. 2 tablespoons mustard seed
10. 3 cups white vinegar. Wash the cucumbers thoroughly.

Method

1. Wash cucumber thoroughly.
2. Drain; cut unpeeled cucumbers into 1/4 slices.
3. In a large bowl, combine the cucumber slices, onions, garlic, and salt.
4. Cover with the crushed ice, mix thoroughly and let stand for 3 hours.
5. Drain off the liquid and remove the garlic (also rinse to get some of the salt off).
6. Combine the sugar, spices, and vinegar and heat just to a boil.
7. Add the cucumber and onion slices; heat 10 minutes.
8. Pack loosely in clean, hot pint jars, leaving 1/2 inch headroom.
9. Tighten lids; process in boiling water bath for 10 minutes. Remove and let it cool.

Activity 7.8 Preserving vegetables using chemicals

Write a recipe and method of making a pickle using carrots, raddish, onions, potatoes, eggplants, bitter tomatoes and okra.

Chutney making

Chutney is a savory condiment made from slow-cooked vegetables, vinegar, and spices. Chutneys are made by slow cooking fruit or vegetables with ginger, garlic, and chilies. Spices and vinegar are added to preserve the chutney and give it a tangy flavor. If you make your own chutneys at home to serve with entrees and appetisers, it requires little effort and produces a unique flavour.

Red tomato chutney making

Ingredients

1. 500gms of red tomatoes
2. 1 clove of garlic
3. 1 medium onion
4. 1/2 teaspoon of ground ginger
5. 50 gms of sugar
6. 200ml of white vinegar
7. A pinch of red food colour

Method

1. Chop vegetables into small pieces.
2. Cook them in a little water until soft. Add vinegar, spices and sugar and cook gently until thick. Bottle in hot sterile jars and cover.

Sauce making

A vegetable sauce is a liquid, cream, or semi solid food, served on or used in preparing other foods. If a vegetable sauce is included in your meal it will add flavour, moisture, and improve on the appearance of your food.

Tomato sauce

Ingredients

1. 10 ripe tomatoes
2. 2 tablespoons of oil
3. 2 tablespoons of butter/margarine
4. 1 onion, chopped 1 green pepper, chopped
5. 2 carrots, chopped
6. 4 cloves of garlic, minced
7. 2 stalks of celery
8. Seasoning
9. 1 bay leaf
10. 2 tablespoons of tomato paste

Method

1. Place water in a pan and bring it to boil. Prepare a large bowl with iced water or cold water.
2. Throw whole tomatoes in boiling water until you see the skin starting to peel. This may take 1 minute.
3. Remove the tomatoes, draining off the water. Place them in the iced water or cold water. Wait until they are cool enough to handle and then remove, peel and squeeze out seeds.
4. Chop 8 tomatoes and (puree) in blender or food processor or a mortar. Chop remaining two tomatoes and set aside.
5. In a large pan over medium heat, cook onion, pepper, carrot and garlic in oil or and butter until onion starts to soften. This will take you about 5 minutes.
6. Pour in the pureed tomatoes. Stir in the chopped ones and seasoning.

Chilli sauce

Ingredients

1. 1 cup red, roughly chopped chillies.
2. 200g diced tomatoes
3. Sliced onions
4. 50mls cooking oil
5. 1tablespoon of crushed garlic and ginger powder
6. 1tablespoon of white pepper
7. 1/4 cup of sugar
8. 1/4 cup of white wine vinegar
9. Salt to taste

Method

Fry the onions.

Add the white pepper, garlic and ginger.

Add the chilles.

Simmer for about 5 minutes.

Remove and allow to cool.

Pour the cooked mixture into the blender or food processor.

Blend or process into a purée to sauce consistency.

Pour back into the pot or pan.

Combine chilli, tomatoes, sugar, salt and vinegar in a saucepan over high heat. Bring to boil. Reduce heat to medium. Simmer, for 7 minutes while stirring occasionally until sauce thickens slightly. Remove from heat. Stand for 5 minutes.

Process mixture in batches until smooth. Pour into hot sterilized jars. Secure lids. Refrigerate for up to 3 weeks.

Mixed vegetable chutney

Ingredients .

1. 1 cup chopped tomatoe pieces 1 tablespoon powder
2. 1 eggplant
3. 1 large diced Irish potato .
4. 1 chopped onion
5. 8 red chillies
6. 1 tablespoon cooking of

Method .

1. Boil water in a pan.
2. Add tomatoes, turmeric powder and pieces of eggplant potato
3. Cover and cook until vegetables become tender
4. Heat the oil and add onion, red chillies and sauté until tender
5. Transfer to the blender or mash together with the vegetables add salt to taste.
6. Check seasoning and serve.

Tomato Marmalade

Ingredients

1. 500gms of sugar
2. 500gms of red firm tomatoes
3. 1 lemon
4. 2 tablespoon of fresh ginger
5. 1 1⁄2 tablespoon of hot chilles

Method

1. Make syrup by combining the sugar with 250mits of water
2. Peel the lemon and keep the peelings, oh the resh ginger
3. Tie the peelings, ginger, chillie in a muslin cloth and place in the boiling syrup.
4. Add the tomatoes and lemon.
5. Boil the mixture fast, stirring from time continuously from time to time until the marmalade sets.
6. Discard the muslin cloth. ·
7. Add the diced peels, stir to blend,
8. Pour in a sterilised jar and cover.

Activity 7.9 Sauce making

Follow one of the given recipes to make a sauce of your choice.

Project:

Follow one of your recipe on processing vegetable and make pickles, chutney and sauces. Pack, label and sell. Write a project report.