(75 hours),  with fresh shortening added twice daily to restore the fryer volume (32). Sensory scores for fries showed few significant differences whether they were fried in fresh shortening or in fat which had been used for 10 days. In comparing the fries from the two shortenings independent of the effect of days of fat use,  panelists judged the overall quality of the fries fried in canola shortening as good or better than fries fried in soybean shortening. Subsequently, Hawrysh (33) has shown that french fries of comparable quality were produced from partially and fully hydrogenated canola and soybean oils,  and tallow. Warner et al. (34) reported higher flavour scores for fries fried in LLCO and partially and fully hydrogenated LLCO than RCO. Environmental Frying Odour Canola and soybean oils,  when heated to frying temperatures develop a strong unpleasant “room odour”  so called because it lingers in the frying environment rather than in the fried food. This odour has been described as fishy,  painty,  plastic and burnt/acrid (35-37). It has been attributed to the volatile products of thermal oxidation of linolenic acid,  since this same odour does not result from high temperature heating of corn,  peanut and cottonseed oils (38). Also,  heating canola oil experimentally under nitrogen reduces the off-odour (39). Studies conducted with LLCO (34,  37,  39) have shown a significant reduction in environmental frying odour. Storage Stability of Fried Foods The shelf life of fried snack foods depends,  to a large extent,  on the quality of the frying medium because significant quantities of the frying medium are absorbed by the food. Potato chips,  for example, increase in fat content from less than 1% to over 30% during frying. Hawrysh et al. (40) tested the stability of potato chips which had been fried in four different oils:  canola,  partially hydrogenated canola, soybean and cottonseed,  under two storage temperatures in the absence of light:  accelerated (60°C) for 12 days,  and ambient (23°C) for 18 weeks. During accelerated storage,  potato chip odour/flavour and off- odour were not affected by oil type. However,  after 18 weeks at room temperature,  chips which had been fried in canola oil had higher typical potato chip odour/flavour and lower off-odour/flavour than chips fried in the other oils. In contrast,  Hawrysh et al. (41) reported higher characteristic odour and lower off-flavour,  rancid and painty odours in tortilla chips fried in LLCO,  corn oil and partially hydrogentated canola and soybean oils than RCO after 16 days of storage at 60°C. No differences were found among oil types for chips stored at room temperature for 24 weeks. Warner et al. (42) also reported potato chips fried in RCO had the lowest flavour quality scores after four months of storage at 25°C compared to chips fried in hydrogenated,  low linolenic and high oleic canola oils. Similarly,  RCO chips had significantly higher amounts of total volatiles than the chips fried in the other three oils,  and high oleic canola oil (HOCO) and LLCO chips had lower amounts of total volatiles than hydrogenated canola oil. Petukhov et al. (43) found chips fried in RCO had greater rates of accumulation of peroxides,  free fatty acid,  conjugated dienoic acids and polar compounds and developed higher levels of total volatiles over the 16 days of storage at 60°C than chips fried in LLCO,  HOCO and hydrogenated canola oil. Chips fried in all oils except hydrogenated canola oil had similar rates of development in painty odour as storage time increased. Chips fried in hydrogenated canola oil exhibited an intense stale/musty odour by the end of 16 days of storage. Baking with Canola Oil Products Traditionally cakes,  cookies and pastries have been prepared by North American consumers with plastic fats like shortening,  lard or butter. Shortening and lard are 100% fat products while butter is only 80% fat. Plastic fats vary in consistency according to their temperature, melting point and the proportion of oil globules within the network of solid fat crystals which gives them structure. Canola oil is converted to shortenings of predetermined consistency through controlled hydrogenation,  blending and aeration. Usually 5-10% of another oil, such as palm,  is added to assure a stable structure of microscopically fine fat crystals (44). The property of plasticity is particularly important in conventional cake shortenings so that they can be creamed without liquefying to trap the fine air bubbles which establish the cake’s grain or cell structure. Plasticity is influenced not only by the proportion of fat crystals but also by their size and strength of association. When most of the fat solids are in the form of small b  '  crystals (<1mm) a shortening is more plastic whereas if the larger b    crystals dominate,  it is more brittle (44). Today emulsifiers and/or surfactants are routinely added to cake shortenings to stabilize batter foams,  assuring high baked volume and a fine,  even grain. They minimize somewhat the importance of a shortening’s crystal size to its creaming power. White cakes made with emulsified canola shortening using an institutional cake recipe with 27% fat were fully comparable to cakes made with soybean shortening in flavour,  tenderness and fineness of grain (44). Since the mid-1980’s,  one trend in commercial cake baking has been to replace plastic fats with liquid oil in combination with appropriate surfactants and increased levels of liquid. These fluid shortenings have been shown in sensory evaluations to produce cakes which are generally scored fresher,  moister and more tender (45). Canola oil has been shown to replace hydrogenated shortening very successfully in white layer cakes when used with an emulsifier system of monoacylglycerols,  polysorbate 60 and sodium stearoyl lactylate. Without the emulsifier system,  oil cakes were dense and tough with a harsh crumb. Including the emulsifiers as 9.5% of the flour weight along with more water (169%),  corrected these defects. The emulsified oil cakes were more tender than the shortening prototype even when the oil was reduced from 52.5% to 10.5% of the flour weight (46). This offers an attractive market opportunity for “light”  cakes. Sensory quality is a high priority for dessert items. Consumers have been found to sample,  but not continue to buy,  fat free or low-fat dessert items when they are not satisfied with the taste (47). Shortenings remain the fat of choice for pastry where fat is cut into the flour to waterproof it intermittently,  resulting in tender,  flaky pie crusts. Like lard,  canola shortenings are generally less plastic than some other shortenings and tend to have somewhat larger crystals, properties that appear to be an advantage in pastry. Data from test pastries comparing canola and soybean shortenings with lard are shown in Table 2. While lard still produced the most tender product, canola pastry was more tender than the soy product and just as flaky as the lard pastry (44).