Frying process

How proline is converted to NPYR has not yet been fully elucidated and could conceivably occur by either of two pathways (29, ). One pathway involves the initial N-nitrosation of proline, followed by decarboxylation, while in the other, proline is first decarboxylated to pyrrolidine followed by N-nitrosation to NPYR. Since the conversion of N-nitrosoproline (NPRO) to NPYR occurs at a much lower temperature than the transformation of proline to pyrrolidine, the pathway involving intermediacy of NPRO is thus the more likely route ( ). It has been reported that preformed NPRO in raw bacon is not the primary precursor of NPYR in cooked bacon (29,33-5), as shown by the fact that ascorbyl paImitate, when added to bacon, inhibits the formation of NPYR (33). However, this by no means rules out the intermediacy of NPRO which could be formed at the higher temperatures attained during the frying process (29,36). 

The mechanism of NPYR formation has been studied by Coleman (37) and Bharucha et al. ( ). Coleman (37) reported that the requirement for a high temperature, the inhibitory effects of water and antioxidants, and the catalytic effect of a lipid hydroperoxide are consistent with the involvement of a free radical in the formation of NPYR. Similarly, Bharucha et al. (29) suggested that, since both NPYR and NDMA increase substantially towards the end of the frying process, N-nitros-amine formation during frying of bacon occurs essentially, if not entirely, in the fat phase after the bulk of the water is removed and therefore by a radical rather than an ionic mechanism. These authors speculated that, during the frying of... 

Many appliances for gas sensors in households are still under development. For example, several attempts have been made in the past to include gas sensors in kitchen ovens to control cooking and frying processes as well as to control the self-cleaning process (pyrolysis). 

Torres, P., Guzman-Ortiz, M. and Ramirez-Wong, B., Revising the role of pH and thermal treatments in aflatoxin content reduction during the tortilla and deep frying processes, J. Agric. Food Chem., 49, 2825, 2001. 

Although the photochemistry of aryl selenoesters and aryl telluroesters is not fully developed, there are some photoreactions of these compounds that resemble a photo-Fries process. Se-/ ara-tolyl selenobenzoate (212) gives, upon irradiation, selenocresol (214), benzaldehyde, and the benzophenone 213 (Scheme 56), which is clearly a photo-Fries product [157,158], Starting from Se-phenyl 2-chlorosele-... 

Kochhar, S. P. (1998). Security in industrial frying processes. Grasas Aceites. 49, 282-302. 

Rossell, J. B. (1998). Industrial frying process. Grasas y Aceites. 49,282-295. 

Zaiifar, A. M., Achir, N., Courtois, F., Trezzani, I., and Trystram, G. (2008). Review of mechanisms, conditions, and factors involved in the oil uptake phenomenon during the deep-fat frying process. Int. J. Food Sci. Technol. 43,1410-1423. 

Acetylcarbazole has been prepared in yields up to 90% by the aluminium chloride catalyzed Fries rearrangement of 9-acetylcarbazole. Photo-Fries rearrangement of this substrate gave an equimolar mixture of 1- and 3-acetylcarbazoles in cyclohexane it has been used to prepare the 1-isomer by reaction in isopropanol. The Lewis acid-catalyzed Fries process was used to prepare 3-phenacetylcarbazole. ... 

Alvarez, M. D., Morillo, M. J., Canet, W. (2000). Characterization of frying process of fresh and blanched potato strips using surface response methodology. Fur. Food Res. Techrwl, 211,326-335. 

There are a number of reactions related to the photo-Fries process, in which cleavage of a bond adjacent to a heteroatom ring substituent leads by way of radical intermediates to a ring-substituted product. As an illustration, N-phenylcaprolactam, which can be regarded as... 

Amino acid analysis confirmed that Maillard browning reactions occurred during the frying process, since basic amino acids such as lysine and arginine decreased significantly, whereas all others decreased only slightly (Table I). 

Oil acts as a heat transfer medium during the frying process which rapidly heats, cooks, and sometimes puffs, dehydrates, or forms a crust around the product. The mechanics of deep fat frying are shown in Fig. 34.32.173 The entering material carries oxygen that temporarily aerates the hot oil, and water that forms steam, with both rapidly swept out... 

The content of polymers and polar components in oils increases during frying process. Size exclusion chromatography and HPLC may be used for the analysis of such components. The content of polar lipids should not exceed about 20%. 

Smoke Point, Fiash Point, and Fire Point The smoke point, flash point, and fire point of an oil are relevant parameters in deep-fat frying processes. The fatty acid composition of the oil is not relevant (unless the oil has short-chain fatty acids, as is the case of butter or coconut oil). The most important effect is generally that of free fatty acids (FFA) in the oil. The following values have been reported for fully refined sunflower oil (with 0.10% free fatty acids) smoke point = 209°C flash point = 316°C fire point = 341°C (5). 

Frozen prefried foods are prepared before ingestion. Deep-fat frying is a most common cooking method for the manufacture of prefried foods. These foods are thus subjected to two different frying processes and a stage in a freezer prior to final cooking and consumption. Several studies have been performed to evaluate the oxidative resistance of sunflower oils when used in frying processes. 

Results show that regular sunflower oil rarely reaches a critical value of 25% of polar compounds in continuous frying processes with frequent turnover, indicating the suitability of sunflower oil for this use. However, use of this oil is recommended only for frying of crisp-type foods with short commercialization periods, ensuring their consumption before detectable levels of deterioration of the absorbed oil are reached (109). 

Mid-Oleic Sunflower Oil With the relatively recent appearance of mid-oleic sunflower oil, researchers have shown an interest in its use in frying processes. Abidi and Warner (120) used the three types of sunflower oil (regular, high, and mid-oleic) in the preparation of french fries, potato crisps, and fresh white corn tortilla chips. However, no general conclusions may be drawn regarding inherent stability as there is no indication of antioxidant type and concentration in the different oils. 

In the frying process, food, such as vegetables, meat, or seafood, is brought in direct contact with hot oil. The food surface becomes golden yellow to dark brown in color and develops a pleasant fried food flavor. 

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