Synthetic and natural antioxidant additives in food stabilization: current applications and future research - Oxidation in Foods and Beverages and Antioxidant Applications - page 281

rendered siscowet lake trout oil at 50 ëC. These authors found that dilauryl
thiodipropionate also failed to act synergistically with BHT, but did react rapidly
with peracids. The lackluster performance in these studies is in contrast to other
studies that show this kind of sulfur derivative to be an effective antioxidant in
many systems. Schwab et al. (1953) found that both thiodiacetic acid and
thiodipropionic acid were excellent antioxidants in the stabilization of soybean
oil and postulated that the activity was due primarily to chelation. Cort (1974)
reported that 0.02% dilaurylthiodipropionate doubled the stability of soy oil at
45 ëC and that its activity was synergistic with ascorbyl palmitate. Hill et al.
(1969) describing an organoleptic study of the effectiveness of antioxidants in
milk fat, found that thiodipropionic acid functioned as an antioxidant. In
contrast, thiodipropionic acid and dilauryl thiodipropionate were found to be
among the least effective antioxidants in a study of flavor stability of foam-dried
whole milk (Tamsma et al., 1963). Other antioxidants studied in this test were,
in decreasing order of effectiveness, lauryl gallate, propyl gallate, nordihydro-
guaiaretic acid, ascorbyl palmitate, BHA, ascorbic acid dihydroquercitin, and
diethylthiodicarbamate.
Wright (1975) showed that dilauryl thiodipropionate was more effective,
alone, than BHA or BHT in the stabilization of soybean oil at room temperature.
Dilauryl thiodipropionate in combination with BHA or BHT gave additively
better performance, but nothing that could be described as synergistic.
Synergistic effects of a combination of DLTDP and BHA were observed in
the stabilization of lard (Kraybill et al., 1949). Shaheen (1984) in a study that
bridges the disciplines of polymer and food chemistry, found that a combination
of vitamin E and dilauryl thiodipropionate provided an excellent stabilizer
system for a styrene butadiene rubber chewing gum base. The author states that
in the absence of an antioxidant, the chewing gum base is prone to catch fire
during processing. BHT is an excellent antioxidant in this system, but there is
consumer demand that it be replaced. Neither dilauryl thiodipropionate nor
vitamin E, alone, makes a suitable antioxidant. When dilauryl thiodipropionate,
alone, is used, the gum base experiences an increase in viscosity as measured
using the Mooney torque test. When solely vitamin E is used, the gum base
experiences a decrease in Mooney torque (BHA, alone, shows constant Mooney
torque during processing). A combination of dilauryl thiodipropionate and
vitamin E in the right ratio provides a fully functional replacement for BHT,
with the opposite effects on torque cancelling each other out. Finnan (1985)
reported that blends of dithiopropionate esters and tocopherol effectively
stabilize oil solutions of carotenoid pigments during frying. Rubin (1991)
describe a process for restoring rancid marine oil that involves treating the oil
with dilauryl thiodipropionate, followed by separation of the oil degradation
products using chromatography.
Ascorbyl palmitate
Ascorbyl palmitate (Fig. 12.6) is the palmitate ester of ascorbic acid. The long
hydrocarbon tail of the fatty acid helps improve the oil solubility of the ascorbic