Fractionation frying oils

Namral as well as synthetic antioxidants can improve the oxidative stability of edible oils. Most common natural antioxidants are mixed tocopherols. Tertiery-butylhydroquinone (TBHQ) is one of the most common synthetic antioxidants used in commercial frying oils. This also costs only a fraction of the natural antioxidants. 

Frying oil Frying time (h) Polar compounds (%) Mol.Wt./ Cone. (g/lOOg oil) Fraction 1 Fraction 2 Fraction 3 Fraction 4 Fraction 5 Fraction 6... 

The earliest form of fractionation was called winterization, simply because tanks of semisolid fats were left quiescent over the northern winter. The higher melting TAGs crystallized in the low ambient temperatures and sedimented in the tanks, leaving liquid olein, suitable for use as a salad or frying oil, to be drawn from the top of the tank. 

If the palm oil is subjected to only a soft pretreatment and low temperature deodorization, much of the naturally occurring P carotene is retained in the oil and tends to concentrate in the olein fractions during fractionation, as shown in Table 1. The various oleins are used in salad and frying oils with a high oxidative stability. The stearins and soft PMF find use in the manufacture of margarines and shortenings. 

PTLC was used to enrich the polar fraction of deep-fried potato chips and vegetable oils used in industrial frying operahons. After PTLC, capillary GC, GC-MS, and NMR were used to quantify sterols and sterol oxides in fried-potato products, as well as the composition of sterols in the oil used for frying [72]. 

However, there are some potential effects of spilled oil on fish. The impacfs on fish are primarily to fhe eggs and larvae, wifh limited effecfs on fhe adulls. The sensitivity varies by species pink salmon fry are affected by exposure to water-soluble fractions of crnde oil, and pink salmon eggs are very tolerant to benzene and water-soluble petroleum. The general effects are difficnlt to assess and document quantitatively, dne to the seasonal and natural variability of the species. Fish rapidly metabolize aromatic hydrocarbons, due to their enzyme system. 

Bouchon et al. (2003) explained that three different oil fractions can be identified as a consequence of the different absorption mechanisms in fried potato cylinders, that is (i) structural... 

Oil content versus moisture content in dry basis for control slices fried at 120,150, and 180°C is shown in Figure 11.2. There is a clear effect of the frying temperature on oil uptake at moisture contents < 1 g water/g dry solid the higher the fiying temperature the lower the oil content -average values of 0.39, 0.35, and 0.30 g/g dry basis for 120, 150 and 180°C, respectively. Figure 11.3 shows kinetics of total oil (TO) uptake and their different fractions (PSO, STO,... 

Figure 11.3 Kinetics of oil uptake fractions and total oil in potato slices during frying at (a) 1 20°C (b) 150°C (c) 180°C. TO total oil PSO penetrated surface oil SO surface oil STO structural oil (reprinted with permission fromj. Food Eng., 2008, 87, 200-212).

The concentrations of aldel des extracted in fraction FI at 207 bar/lS0°C were 3 to 8 times higher than those extracted at 345 bar/50°C The concentrations of 2,4-dienaIs which are responsible for the deep-fat fried odor of mai fiits and oils 14) were very high compared to similar compounds found in beef fat, and they were concentrated up to 34-fold in firaction FI compared to non-extracted control. 2,4-Decadienal (E,E) is an apparent precursor of 2-pentylpyridine, and it has also been found that the 2,4-dien contribute to fatty, oUy and tallowy odor of fats 36). 

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