Info

U.S. Code of Federal Regulations, Title 21, Part 110, Current Good Manufacturing Practice in Manufacturing, Packing or Holding Human Food, U.S. Government Printing Office, Washington, D.C., 1996.

U.S. Code of Federal Regulations, Title 21, Part 108, Emergency Permit Control, U.S. Government Printing Office, Washington, D.C., 1996.

U.S. Code of Federal Regulations, Title 21, Part 113, Thermally Processed Low-Acid Foods Packaged in Hermetically Sealed Containers, U.S. Government Printing Office, Washington, D.C., 1996.

U.S. Food and Drug Administration, Guide to Inspections of Acidified Food Manufacturers, 1998. U.S. Food and Drug Administration, Guide to Inspections of Low Acid Canned Food Manufacturers, Part 1 (PB97-196141), 1996; Part 2 (PB97-196158), 1997; Part 3, 1998.

Elizabeth Andress University of Georgia Athens, Georgia

CAÑOLA OIL BACKGROUND

The term canola refers to cultivars of an oilseed crop, known in many countries as rapeseed, that is a major source of food and feed throughout the world. The crop has become the world's third most important edible oil source after soybeans and palm (1). The development by plant breeders of low erucic acid and low glucosinolate (double-low) varieties of rapeseed has proved pivotal to the rapid expansion in production and use of rapeseed worldwide. The rapeseed industry in Canada adopted the name canola in 1979 to distinguish those cultivars of Brassica napus and Brassica rapa (formerly, B. campestris) that are genetically low in both erucic acid and glucosinolates. Since the oil and meal from the double-low cultivars are nutritionally superior to those of earlier-grown varieties, the generic term canola also was used to identify the products from these varieties. The definition of canola was last updated in 1997 to take account of the development of mustard seed, Brassica júncea, varieties with low levels of erucic acid and glucosinolates. The definition adopted by the Canola Council of Canada in 1997 reads: "The oilseeds shall be the seed of the genus Brassica which shall contain less than 18 micromoles of total glucosinolates per gram of whole seed at a moisture content of 8.5%; and the oil component of which the seed shall contain less than one percent of all fatty acids as erucic acid" (2). Canola is not an exclusive Canadian trademark; the oilseed industry in other countries, such as Australia, Japan, the United States, and the United Kingdom, also have accepted canola to describe double-low rapeseed.

Canola has become Canada's second most valuable crop after wheat. Its rapid rise in economic importance is due to some positive agronomic advantages and the marketing alternatives it offers producers. Canada is the leading exporter of seed in the world, exporting an average volume of 2.8 million tons annually over the period 1992-1997 (3); Japan is the major importer of Canadian rapeseed/canola. In 1996-1997, the domestic crush of seed in Canada ex ceeded seed export for the first time (2.71 vs 2.52 million tons). Domestic utilization of canola oil in 1996—1997 was 6.82 x 105 t, up from 4.33 x 105 t in 1992-1993, while oil exports increased from 3.67 x 105 to 5.07 x 10® over the same period (4). Among the processed oils and fats, canola has made substantial gains into the shortening and salad and cooking oil segments of the Canadian market during the past decade. Canola accounted for 70.4% of all deodorized fats and oils, 72.8% of the vegetable oils, and more than 80% of the salad oils produced in Canada in the calendar year 1997 (4). Although current canola production in the United States is relatively small, there is a growing demand for canola products; for 1996-1997 alone, Canada exported 4.24 x 10® t of oil and 8.49 x 1051 of meal to the United States, which accounted for more than 80% of the total oil and meal exports (5).

Canola oil is characterized by a low level of saturated fatty acids and a relatively high content of oleic acid; canola oil is second to olive oil in oleic acid content among common vegetable oils. The blood cholesterol-lowering effect observed in humans, when canola oil made up a major portion of the total dietary fat (6), has been an important factor in the increased use of canola products in the world's markets. Rapeseed/canola now ranks third, behind soybean oil and palm oil, in the global disappearance of fats and oils.

Botanical Origin

Although rapeseed production in Canada commenced after World War II, the cultivation of Brassica oilseeds has a long history in Europe and Asia (7). Unlike other oilseed crops, rapeseed is not a product of a single species, but comes from two species of the genus Brassica: B. napus and B. rapa. The cytogenic relationships between rapeseed and its close relatives have been discussed extensively in several reports and are important in understanding the origin, evolution, and plant-breeding strategies of the Brassica species (811). The two rapeseed species along with Brassica juncea (mustard), commonly referred to as oilseed Brassicas, collectively provide more than 13.2% of the world's edible oil supply (11). The small, round Brassica seeds contain 40 to 44% oil (dry weight basis) and produce a high-protein content (38-41%) oil-free meal. Within the rapeseed species, both spring and winter cultivars exist; the latter are higher yielding than the spring varieties but are less winter hardy than cereals. Winter cultivars of B. napus predominate in Europe, whereas spring cultivars of B. napus and B. rapa are grown in Western Canada. B. napus varieties have a generally higher seed-yielding potential (15-20%) than those of.B. rapa, but they require an additional 8 to 15 frostfree days to mature; in Western Canada, cultivars ofB. napus require 95 to 105 days for maturity (9,12).

Development of Double-Low Cultivars

Rapeseed production in Canada began with the introduction of seed of B. napus from Argentina and B. rapa from Poland; these materials, highly heterogenous, constituted the seed stock for the establishment of breeding programs. Although improvements in seed yield and oil content were the first objectives, particular emphasis was also given to oil and meal quality. The elimination of nutritionally un desirable components—erucic acid, found to cause cardiac lipidosis in several animal species (13), from the oil and sulfur-containing glucosinolates from the meal—became a target at the early stages of the breeding programs. Changes in fatty acid composition were made by introducing the inherited traits of low erucic acid into adapted lines of B. napus and B. rapa. Canadian breeders also accomplished the transfer of genes responsible for the low glu-cosinolate characteristic into rapeseed varieties. These sulfur-containing constituents are hydrolyzed by an endogenous enzyme, called myrosinase (thioglucosidase, EC 3.2.3.1), into thiocyanates, isothiocyanates, and under some conditions nitriles (Fig. 1) when seed cells are ruptured (eg, during seed crushing). The characteristic odor and flavor of Brassica vegetables and condiments (mustard) are largely due to the presence of these compounds. Glucosinolate breakdown products also reduce the palat-ability and, in nonruminant animals, adversely affect the iodine uptake by the thyroid gland (14,15). Breeding for lower glucosinolate content of the seed has resulted in nutritional upgrading of rapeseed meal for all classes of livestock and poultry. Further reduction in glucosinolates content is required, particularly of the indoyl glucosinolates (16), if proteins from canola meal are to be used in human food formulations. This has been partly accomplished by extraction processes employed in preparation of protein concentrates and isolates (17). The ultimate solution would be to breed varieties free of both alkenyl and indolyl glucosinolates. Total elimination of glucosinolates in canola is a future possibility since a strain of B. rapa essentially free of alkenyl glucosinolates has been produced (16).

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