Deep-Frying Fats

Sulfates or sulfonates Alkali metal salts of sulfated alcohols, sulfonic acid salts alkyl-aryl sulfonates sodium laiiryl sulfate Nonaqiieoiis systems mixed aqueous and nonaqiieoiis systems oil-well drilling muds spent H3SO4 recovery deep-fat frying... 

JASWIR I, MAN Y B c and KITTS D D (2000) Use of natural antioxidants in refined pahn olein during repeated deep-fat frying, Food Res Int, 33, 501-8. 

Figure 6. Representative batch of akara, a bread-like product made by deep-fat frying cowpea paste. Reproduced with permission from Ref. 6. Copyright 1980, Institute of Food Technologists.

Nut uses of roasted peanuts and sunflower kernels and deep fat fried soybean "nuts" are well known. 

Chin-chin is crisp, slightly sweet, golden brown knots of pastry. These deep fat fried cakes are made in different shapes and styles. Chin-chin is often flavored with vanilla extract, nutmeg, caraway seed, orange or lemon rind. The African panel preferred the chin-chin with no substitution for all characteristics except appearance. The non-African panel preferred chin-chin without any substitutions for all characteristics. The soybean flour was the most desirable substitution at 30% of the all purpose flour. 

Considerable efforts have also been made toward the development of novel compounds with superior antioxidant properties. Some attempts were also made to introduce new synthetic polymeric compounds which are non-absorbable and non-toxic. These are generally hydroxyaromatic polymers with various alkyl and alkoxyl substitutions. Such compounds are usually very large molecules and their absorption from the intestinal tract is practically nil. In addition to their reportedly high antioxidant activity, they are non-volatile under deep-fat frying conditions, which result in nearly quantitative carry-through to the fried items, but they have not yet received FDA approval. 

Contents I. Food Deep-Fat Frying A General Overview 210... 

B. Heat and mass transfer during deep-fat frying 214... 

Deep-fat frying can be defined as a process of cooking food by immersing them in edible oil at a temperature above the boiling point of water, and therefore, may be classified as a dehydration process (Farkas, 1994). Frying temperatures usually range between 130 and 190 °C, but most... 

FIGURE 5.1 Schematic diagram of simultaneous heat transfer (left-hand side of the figure) and mass transfer (right-hand side of the figure) during deep-fat frying (with the courtesy of M. C. Moreno). 

From an engineering perspective, deep-fat frying can be defined as a unit operation where heat and mass transport phenomena occur simultaneously. Convective heat is transferred from the frying media to the surface of the product, which is thereafter conducted within the food. Mass transfer is characterized by the loss of water from the food as water vapor and the movement of oil into the food (Singh, 1995). 

FIGURE 5.4 Diagram showing the three locations of oil in the product microstructure after deep-fat frying from Bouchon et al. (2003). 

Oil reduction in deep-fat-fried products may be obtained through prefrying and/or postfrying treatments. Prefrying treatments are mainly based on the marked effect that the crust microstructure has in oil absorption, and mainly intend to reduce surface permeability. Postfrying treatments aim to remove surface oil before postcooling suction begins. 

Albert, S. and Mittal, G. S. (2002). Comparative evaluation of edible coatings to reduce fat uptake in a deep-fat fried cereal product. Food Res. Int. 35, 445-458. 

Baumann, B. and Escher, E. (1995). Mass and heat transfer during deep fat frying of potato slices I. Rate of drying and oil uptake. Lebensmittel-Wissenschaft Technologie. 28, 395-403. Besaratinia, A. and Pfeifer, G. (2004). Genotoxicity of acrylamide and glycidamide. J. Natl. Cancer Inst. 96,1023-1029. 

Blumenthal, M. M. (1991). A new look at the chemistry and physics of deep-fat frying. Food Technol. 45, 68-71. 

Gazmuri, A. M. and Bouchon, P. (2009). Analysis of wheat gluten and starch matrices during deep-fat frying. Food Chem. doi 10.1016/j.foodchem.2009.01.020. 

Keller, C. H., Escher, F., and Solms, J. A. (1986). Method of localizing fat distribution in deep-fat fried potato products. .ebensmittel-VJissenschaft Technologie. 19,346-348. 

Mallikarjunan, P., Chinnan, M. S., Balasubramaniam, V. M., and Phillips, R. D. (1997). Edible coatings for deep-fat frying of starchy products. Lebensmittel-Wissenschaft Technologic. 30, 709-714. 

Mellema, M. (2003). Mechanism and reduction of fat uptake in deep-fat fried foods. Trend. Food Sci. Technol. 14, 364—373. 

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