Frying fats

Smoke, Flash, and Fire Points. These thermal properties may be determined under standard test conditions (57). The smoke poiat is defined as the temperature at which smoke begias to evolve continuously from the sample. Flash poiat is the temperature at which a flash is observed whea a test flame is appHed. The fire poiat is defiaed as the temperature at which the fire coatiaues to bum. These values are profouadly affected by minor coastitueats ia the oil, such as fatty acids, moao- and diglycerides, and residual solvents. These factors are of commercial importance where fats or oils are used at high temperatures such as ia lubricants or edible frying fats. 

The overwhelming consideration in regard to lipid deterioration is the resulting off-flavors. Aldehydes, both saturated and unsaturated, impart characteristic off-flavors in minute concentrations. Terms such as painty, nutty, melon-like, grassy, tallowy, oily, cardboard, fishy, cucumber, and others have been used to characterize the flavors imparted by individual saturated and unsaturated aldehydes, as well as by mixtures of these compounds. Moreover, the concentration necessary to impart off-flavors is so low that oxidative deterioration need not progress substantially before the off-flavors are detectable. For example, Patton et al (1959) reported that 2,4-decadienal, which imparts a deep-fried fat or oily flavor, is detectable in aqueous solution at levels approaching 0.5 ppb. 

Sample b c roasted (bread, coffee, peanut, walnut, malt), burnt, popcorn, slightly rancid, heated cooking oil Sample ds heated cooking oil, deep-frying fat, solvent, old paint Since the panel found no difference between samples b and c in the triangle test, it was not possible to ask for two distinct "profiles" in the descriptive test. However, it was evident that samples b and c were the most attractive oils from a flavor point of view. There were similarities with sesame oil and Swedish crispbread. 

Fig. 34.32. Changes occurring during deep fat frying. (From Fritsch, C.W., "Measurements of Frying Fat Deterioration," J. Am. Oil Chem. Soc., 58, 272-274 (1981). With permission.)...

CHARACTERISTICS OF ANIMAL FAT-BASED SHORTENINGS AND FRYING FATS... 

Routine analysis for frying fat deterioration has been reviewed by Gertz (104). Usually, more than two methods are required when using chemical analysis because no single group of compounds has been identified as a key indicator of oxidative degradation of frying fats. 

TABLE 17. Hydrogenated Canola Oils for Margarines, Shortenings, and Frying Fats. 

Frying Fats Large amounts of canola oil are used as lightly hydrogenated (IV 90), stable, but pourable frying fat. Canola oil is uniquely suited to combine good stability with pourability because of its fatty acid composition. 

The use of palm oil in food dates back 5000 years. For edible and nonedible uses, palm oil is normally refined. However, even today, unrefined palm oil is still used for cooking in certain African villages much the same way as it used to be. Examples demonstrating the range of palm oil applications in food are shortening, margarine, vanaspati, deep frying fat, and specialty fats. 

Palm stearin, the solid fraction of palm oil, has the edge over tallow because of the assurance of expanding supply, while world production of tallow has stagnated. Applications where stearin could replace tallow are in shortenings, frying fats, and soaps. Lard could also be substituted by palm stearin or RED palm oil in most of its applications. 

Synthetic antioxidants, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG), ascorbyl palmitate, and tertiary-butyl-hydroquinone (TBHQ), are used in soybean cooking oils and frying fats (230). These antioxidants are typically added at 0.01% for one antioxidant and 0.02% total for two or more. Natural antioxidants, derived from sage, rosemary, and green tea, are increasingly popular because of consumer preferences for natural food ingredients (231). 

Pan and food release agents. Lecithin-based release agents are employed in many applications such as frozen waffle manufacture, bakery products, pizza baking, and pasta products. Most industrial griddle frying fats are formulated with lecithin, solely for its release functionalities (7). The products may be spray- or brush-applied to achieve a thin film capable of promoting easy release of baked items from pans and belts. Bakery release agents may contain 2-6% lecithin in a variety of oil bases, and they may also be formulated with particulate matter to provide an additional mechanical release. 

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