A Complete Course in Canning and Related Processes

Volume 3 Processing Procedures for Canned Food Products

Susan Featherstone

• Publisher: Woodhead Publishing
• Year: 2015
• ISBN:
  9780857096876
• Edition: 14
• Topic: Tecnología e ingeniería
• Subtopic: Ciencia de los alimentos

A Complete Course in Canning and Related Processes: Volume 3, Processing Procedures for Canned Food Products, Fourteenth Edition provides a complete course in canning and is an essential guide to canning and related processes.

Professionals and students in the canning industry have benefited from successive editions of the book for over 100 years. This major new edition continues that reputation, with extensively revised and expanded coverage.

The book's three-title set is designed to cover all planning, processing, storage, and quality control phases undertaken by the canning industry in a detailed, yet accessible fashion.

Major changes for the new edition include new chapters on regulation and labeling that contrast the situation in different regions worldwide, updated information on containers for canned foods, and new information on validation and optimization of canning processes, among many other topics.

• Extensively revised and expanded coverage in the field of food canning
• Designed to cover all planning, processing, storage, and quality control phases undertaken by the canning industry in a detailed, yet accessible fashion
• Examines the canning of various fruits and vegetables, in addition to meat, milk, fish, and composite products
• Updated to cover the canning of ready meals, pet food, and UHT milk

Part One

Fruits, Vegetables, and Pulses

1

Canning of vegetables

Abstract

Canned vegetables are a convenient effect way of preserving vegetables for consumption when they are not readily available. Canned vegetables are full of essential nutrients, and in some cases the nutrients are more readily digestible than in the fresh equivalent. Most vegetables have naturally relatively high pH and thus fall into the low-acid group of foods. They therefore require a full sterilisation treatment, unless they are acidified. The kinds of microorganisms that can be found associated with most vegetables can cause food poisoning or thermophilic spoilage, and therefore it is very important that the sterilisation processes are well designed and carefully controlled. This chapter describes the unique requirements for canning many different vegetables; it is in brine, or as a solid pack.

Keywords

Vegetable

Low-acid

Quality

Brine

Washing

Peeling

Blanching

Processing

Temperature.

Acknowledgments

The author thanks Dr. Gerald D. Kuhn, of Pennsylvania State University, for his contributions to earlier versions of the section on mushrooms; Dr. F. William Cooler (retired), of Virginia Polytechnic Institute and State University, for his contributions to earlier revisions of the section on sweet potatoes; and Mr. Richard N. Kimball, Former Head, Processing Section, National Food Processors Association Laboratory at Dublin, CA, for his advice and suggestions with regard to use of data from NFPA (1982) and 30-L (1984) on thermal processing requirements for canned low-acid foods, which have not changed since the 12th edition of this publication.

1.1 Introduction

Canned vegetables can be just as healthy as fresh vegetables. Studies have shown that after you prepare them in a meal, most frozen, fresh, and canned vegetables have similar amounts of most nutrients. Canned vegetables are very fresh when they are processed, so they are at their peak nutrition. Although they do lose some nutrients in the canning process (e.g., some vitamin C and B vitamins because these are water soluble and sensitive to heat), the heat process actually increases the availability of lycopene and beta-carotene.

A concern with canned vegetables is the sodium content, as salt/brine (sodium chloride) is often added to help maintain the flavour of vegetables during the canning process. The amount of salt added can be reduced and the flavour and quality still maintained.

As a group of products, canned vegetables are usually all in the low-acid pH range, which means that unless they are acidified, they have to be sterilised to a minimum of Fo 3 to be commercially sterile and shelf stable at room temperature. Table 1.1 gives a list of the naturally occurring pH of many vegetables.

Table 1.1

pH of some fresh vegetables

Vegetable	pH	Vegetable	pH	Vegetable	pH
Artichokes	5.50 –6.00	Eggplant	5.50–6.50	Peas	5.70–6.80
Asparagus	6.00–6.70	Garlic	5.80	Peppers, green	5.20–5.95
Bamboo shoots	5.10–6.20	Horseradish	5.35	Potatoes	5.40–5.90
Beans	5.60–6.50	Mushrooms	6.00–6.70	Pumpkin	4.90–5.50
Beets	5.30–6.60	Okra	5.50–6.60	Spinach	5.50–6.80
Cabbage	5.20–6.80	Olives	6.00–7.50	Squash	5.20–6.50
Carrots	5.90–6.40	Onion white	5.30–5.85	Turnips	5.30–5.90
Corn	5.90–7.30	Palm, heart of	5.70–6.70	Water chestnut	6.00–6.20

The process times and temperatures for low-acid products given here are those recommended by the National Food Processors Association Bulletin 26-L and Bulletin 30-L. These processes give good guidelines for processing, but should always be verified by a competent thermal process authority for individual products and recipes. The maximum fill weights listed for some of the products may not be suitable for all operations. It is always recommended that heat penetration tests are done to verify the safety of the processing parameters. If the fill weight critical control factor is exceeded, then this constitutes a processing deviation and must be assessed by a competent thermal processing authority.

The minimum initial temperature stated is the average temperature of the contents of the coldest can in the retort at the time that the steam is turned on for the start of the process. The can sizes used are all in Imperial units. See Table 9 of Appendix for the conversion of imperial to metric can sizes (Tables 1.2–1.4).

Table 1.2

Process times and temperatures for asparagus cuts, white or green, including soup cuts in brine

Can size	Maximum fill weight		Minimum initial temperature		Minutes at retort temperature
	Oz.	g	°F	°C	116 °C (240 °F)	118 °C (245 °F)	121 °C (250 °F)
211 × 304	5.3	150	70	21	22	17	13
			120	49	21	15	12
211 × 304	6.5	184	70	21	24	19	16
			120	49	23	18	15
211 × 400	6.8	193	70	21	20	15	12
			120	49	19	14	12
211 × 400	8.5	241	70	21	23	18	15
			120	49	22	17	14
300 × 407	9.7	275	70	21	26	19	15
300 × 409	10	284	120	49	23	17	13
300 × 407	10.7	303	70	21	30	24	19
300 × 409	11	312	120	49	27	21	17
603 × 700	68	1928	70	21	43	32	25
			120	49	36	27	20

Table 1.3

Asparagus spear, tips down in brine in still retorts

Can size	Maximum fill weight		Minimum initial temperature		Minutes at retort temperature
	Oz.	g	°F	°C	116 °C (240 °F)	118 °C (245 °F)	121 °C (250 °F)
211 × 304	6.5	184	70	21	27	22	19
211 × 400	8.2	233	120	49	25	20	17
211 × 510	11.9	337
300 × 407	11.5	326
307 × 409	15.5	439
603 × 408	45.5	1290	70 120	21 49	32 29	25 23	21 19

Note: These processes do not apply to peeled spears, nor do they apply to spears of more than 28.6 mm in diameter.

Table 1.4

Asparagus spear, tips up in brine in still retorts

Can size	Maximum fill weight		Minimum initial temperature		Minutes at retort temperature
	Oz.	g	°F	°C	116 °C (240 °F)	118 °C (245 °F)	121 °C (250 °F)
211 × 304	6.7	190	70	21	30	25	21
211 × 400	8.4	238	120	49	28	23	20
211 × 510	12.2	346
300 × 407	11.8	335
307 × 409	15.9...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Woodhead Publishing Series in Food Science, Technology and Nutrition
• Preface
• Introduction
• Part One: Fruits, Vegetables, and Pulses
• Part Two: Meat, Fish, and Milk
• Part Three: Canning of Preserves and Pickles
• Part Four: Canning of Composite Products
• Appendix
• Glossary
• Index